CURE Epilepsy Discovery: CURE Epilepsy Grantee Discovers Specific Alterations in the Inhibitory Neurotransmitter System in Infantile Spasms (IS)

Key Points:

  • Infantile spasms (IS), also called West syndrome, is a rare epilepsy syndrome associated with stereotypical spasms, developmental delay, and a telltale brainwave pattern. Medications used to treat IS are not effective in everyone with IS and are associated with side effects.
  • CURE Epilepsy launched the Infantile Spasms Initiative (IS Initiative) in 2013 with a team science approach to bring together groups of investigators working on diverse topics related to IS; this one-of-a-kind initiative in epilepsy research contributed immensely to today’s understanding of IS and its mechanisms.
  • One of the Initiative’s grantees, Dr. Chris Dulla, developed a mouse model that simulates the neuronal excitation and inhibition relevant to IS. Animal models are incredibly useful to understanding the biological mechanisms underlying IS, and by better understanding the interplay between neural excitation and inhibition in IS, there is hope that we can develop targeted therapies.

 

Deep dive

Infantile spasms (IS) is a devastating and rare epilepsy syndrome that is typically seen in the first year of a child’s life, most commonly between four and eight months of age.[1, 2] One in 2,000 children is affected by infantile spasms, and worldwide it is estimated that one baby is diagnosed with IS every 12 minutes.[3] IS consists of the following characteristics: subtle seizures consisting of repetitive, but often subtle movements—such as jerking of the mid-section, dropping of the head, raising of the arms or wide-eyed blinks; developmental delay and cognitive and physical deterioration; and a signature disorganized, atypical brainwave pattern called “hypsarrhythmia.”[4, 5] Potential causes include brain injuries or infections, issues with brain development and malformations, gene variants, or metabolic conditions. IS can sometimes have an underlying genetic cause as well.[2, 6] Often, infants appear to develop normally until spasms start, but then show signs of regression. Some infants may have hundreds of such seizures a day.

Current treatment for IS consists of hormonal therapy such as adrenocorticotropic hormone and prednisone, and antiseizure medications such as vigabatrin. These medications are effective in approximately half of the patients with IS.[7, 8] Even infants who have been diagnosed in a timely fashion may not respond to the available treatments, or they may suffer adverse side effects. There is no reliable way to predict who will respond favorably to medications.

As there was a dire need to better understand and treat IS, because there was no advocacy group or organization dedicated to IS and no organization was focusing on finding treatments or cures, CURE Epilepsy stepped in and leveraged our expertise as well as our resources to assemble the Infantile Spasms (IS) Initiative in 2013. Committing $4 million, the Initiative brought together eight research teams working on various aspects of IS. [9] Team science” is a unique way of conducting research that leverages the strengths and expertise of scientists trained in different but related fields to solve a single, complex problem. CURE Epilepsy’s IS Initiative was the first team science approach in the epilepsy research community, and teams in the Initiative benefitted from sharing knowledge and resources to expedite understanding of IS. [9] Collectively, the Initiative studied the basic biology that may explain what causes IS, searched for biomarkers and novel drug targets, and explored ideas for improved treatments for the condition. [9]

One of the eight teams involved in the Initiative was led by Dr. Chris Dulla and his laboratory at Tufts University. Dr. Dulla’s team developed an animal model for IS by targeting a gene called Adenomatous polyposis coli (APC). For the epilepsies in general, animal models are crucial to understanding the biological mechanisms that cause seizures. Dr. Dulla’s team developed an animal model for IS by targeting a gene called Adenomatous polyposis coli (APC). Mice that were genetically altered to have a decrease in the activity of APC exhibited many of the features that were reminiscent of human IS.[10] The development of this mouse model (called “APC cKO”) was an important step in IS research as it provided a way for scientists to study IS and the mechanisms that may cause it.

Broadly speaking, there are two kinds of neurons (brain cells): “excitatory” neurons that activate other neurons, and “inhibitory” neurons that restrain other neurons. A fine balance between excitation and inhibition is critical for the brain to function, and in epilepsy, this delicate balance may be disturbed. Inhibitory neurons are modulated by a neurotransmitter called gamma amino butyric acid (GABA). In the current study, Dr. Dulla’s team wanted to study GABAergic neurotransmission in the APC cKO model. Previous studies have shown a link between GABAergic neurotransmission and IS; specifically, alterations in GABAergic transmission have been found in animal models of IS [11, 12] and in human patients with IS.[13] The ultimate goal is to better understand the interplay between excitatory and inhibitory neurotransmission in IS.[14]

In a recent study that was published in February 2023, Dr. Dulla’s team studied inhibitory neurons (also called “interneurons,” abbreviated to “INs”). They looked at a certain kind of interneuron, called a parvalbumin-positive interneuron (PV+ IN) and studied the way these interneurons looked under the microscope (i.e., their anatomy) as well as the way they functioned (i.e., their physiology). In humans, IS has a time course in terms of when seizures start. To recreate this in their mouse model, the team studied APC cKO mice at multiple time points: in infancy (postnatal days 9 and 14), and then later, as adults, and compared them to mice that did not have the genetic mutation (i.e., “wild-type” mice). The goal of the study was to understand what happens to PV+ INs in the APC cKO mouse model of IS.[14]

In normal brain development, an excess of PV+ INs are made, but then they disappear over time. The first discovery Dr. Dulla’s team made was that in APC cKO mice, there is an excess of PV+ IN death. The second important finding was that in APC cKO mice, the death of these PV+ INs occurred earlier in development as compared to wild-type mice.[14] This change in the pattern of death of PV+ INs could mean that there are subtle changes taking place in the neural circuit. Since the primary role of interneurons is to keep brain activity in check, an excess of interneurons dying very quickly may mean that the excitatory neurons run amok. In contrast, other types of interneurons did not show accelerated dying, but this change was specific to PV+ INs.[14] The change in the pattern of PV+ IN cell death in APC cKO mice was also reflected in the functioning of the brain as studied by looking at the electrical activity in the brain.14 The changes seen in the interneuron death and associated function were more pronounced at postnatal day 9 (as compared to postnatal day 14), which suggests that this is the critical period in brain development in this model, when, if GABAergic inhibition is perturbed, may lead to IS and associated symptoms.

In totality, Dr. Dulla’s findings regarding GABAergic neurotransmission and PV+ INs are complicated with respect to the sequence and timing of events. However, there is a variation in the way the inhibitory GABAergic neuronal circuitry develops and matures in APC cKO mice that suggests a critical window of events that if perturbed, may lead to spasms and behavioral impacts later on. This work positions PV + INs as a potential target to treat IS, and perhaps even offers avenues for timely diagnosis.[14] This perturbation of inhibition during a critical period in development may contribute to spasms and seizures later in life. The development of the GABAergic circuitry depends on brain activity; hence, the changes in activity of the neural circuitry seen in APC cKO mice interneurons may contribute to long-term changes in the brain. The exact link between the PV+ IN death in early development and behavioral spasms needs to be investigated in more detail, but this work lays the foundation to continue studying inhibitory transmission in IS. Future studies will reveal if stopping this excess PV+ IN death may be a therapeutic target or a cure for Infantile Spasms.

 

 

Literature Cited:

  1. Hrachovy RA. West’s syndrome (infantile spasms). Clinical description and diagnosis Adv Exp Med Biol. 2002;497:33-50.
  2. Shields WD. Infantile Spasms: Little Seizures, BIG Consequences. Epilepsy Curr. 2006;6:63-69
  3. Smith MS MR, Mukherji P. Infantile Spasms. Treasure Island (FL): StatPearls [Internet]; StatPearls Publishing Updated 2022 May 29.
  4. Eling P, Renier WO, Pomper J, Baram TZ. The mystery of the Doctor’s son, or the riddle of West syndrome Neurology. 2002 Mar 26;58:953-955.
  5. Lux AL. West & son: the origins of West syndrome Brain Dev. 2001 Nov;23:443-446.
  6. Osborne JP, Edwards SW, Dietrich Alber F, Hancock E, Johnson AL, Kennedy CR, et al. The underlying etiology of infantile spasms (West syndrome): Information from the International Collaborative Infantile Spasms Study (ICISS) Epilepsia. 2019 Sep;60:1861-1869.
  7. Knupp KG, Coryell J, Nickels KC, Ryan N, Leister E, Loddenkemper T, et al. Response to treatment in a prospective national infantile spasms cohort Ann Neurol. 2016 Mar;79:475-484.
  8. Pavone P, Striano P, Falsaperla R, Pavone L, Ruggieri M. Infantile spasms syndrome, West syndrome and related phenotypes: what we know in 2013 Brain Dev. 2014 Oct;36:739-751.
  9. Lubbers L, Iyengar SS. A team science approach to discover novel targets for infantile spasms (IS). Epilepsia Open. 2021;6:49-61.
  10. Pirone A, Alexander J, Lau LA, Hampton D, Zayachkivsky A, Yee A, et al. APC conditional knock-out mouse is a model of infantile spasms with elevated neuronal ?-catenin levels, neonatal spasms, and chronic seizures Neurobiol Dis. 2017 Feb;98:149-157.
  11. Marsh E, Fulp C, Gomez E, Nasrallah I, Minarcik J, Sudi J, et al. Targeted loss of Arx results in a developmental epilepsy mouse model and recapitulates the human phenotype in heterozygous females Brain. 2009 Jun;132:1563-1576.
  12. Katsarou AM, Li Q, Liu W, Moshé SL, Galanopoulou AS. Acquired parvalbumin-selective interneuronopathy in the multiple-hit model of infantile spasms: A putative basis for the partial responsiveness to vigabatrin analogs? Epilepsia Open. 2018 Dec;3:155-164.
  13. Bonneau D, Toutain A, Laquerrière A, Marret S, Saugier-Veber P, Barthez MA, et al. X-linked lissencephaly with absent corpus callosum and ambiguous genitalia (XLAG): clinical, magnetic resonance imaging, and neuropathological findings Ann Neurol. 2002 Mar;51:340-349.
  14. Ryner RF, Derera ID, Armbruster M, Kansara A, Sommer ME, Pirone A, et al. Cortical Parvalbumin-Positive Interneuron Development and Function Are Altered in the APC Conditional Knockout Mouse Model of Infantile and Epileptic Spasms Syndrome J Neurosci. 2023 Feb 22;43:1422-1440.

CURE Epilepsy Discovery: Implantable Devices Represent a Novel Way to Detect and Treat Epilepsy

Key Points:

  • Approximately one-third of people with epilepsy do not respond to anti-seizure medications and there are limited treatment options for these treatment-resistant cases.
  • Implantable epilepsy devices offer novel avenues to detect and treat seizures by recording seizure activity from neurons (brain cells) in high-resolution and stimulating these neurons in a way that halts seizures.
  • Brian Litt at the University of Pennsylvania was funded by CURE Epilepsy in 2011, and his work has led to the development of electrodes and technology that offer incredible precision in recording from and stimulating neurons.
  • Litt’s trainees, Dr. Jonathan Viventi at Duke University and Dr. Flavia Vitale at the University of Pennsylvania, are continuing their work to develop cutting-edge implantable devices to understand and treat epilepsy at their own laboratories.

 

Deep dive

People with epilepsy are often prescribed anti-seizure medications (ASMs), and while they are effective in many people, about 30% of those with epilepsy continue to experience seizures. Resective surgery, where the part of the brain that generates seizures is removed, may be an option for some, but not all, people with treatment-resistant epilepsy (also called “refractory” epilepsy).[1] Devices for epilepsy represent an innovative treatment modality that has much to offer to those with treatment-resistant epilepsy.

Devices for epilepsy fall into two main categories: 1) wearable, seizure-alert devices, and 2) devices that are implanted in the body. Wearable devices can track seizures and alert a caregiver to the occurrence of a seizure. Wearable devices can have a positive impact on quality of life, and can contribute to the empowerment of the person with epilepsy by encouraging self-monitoring and self-management.[2,3] Implantable devices for epilepsy include neurostimulation devices. For example, responsive neurostimulation (RNS) devices) and deep brain stimulation (DBS) devices) reduce seizures by applying electrical stimulation to modulate brainwaves in specific areas of the brain.  The RNS device can be thought of as a pacemaker for the brain; it is implanted near the seizure focus and allow for insertion of wires that send electrical pulses to interfere with seizure activity in surface areas of the brain, whereas the DBS sends electrical pulses through wires to specific areas deep within the brain that are involved with seizures.

Implantable devices hold substantial promise for those with refractory epilepsies who have inadequate therapeutic alternatives. It has been suggested that implantable devices may even become alternatives to multiple ASMs and resective epilepsy surgery.[4] The promise that devices hold for epilepsy therapy aligns with CURE Epilepsy’s goal to identify and fund cutting-edge research, challenging scientists worldwide to collaborate and innovate in pursuit of a cure for epilepsy. To this end, this CURE Epilepsy Discovery features our grantee, Dr. Brian Litt who is jointly appointed at the Perelman School of Medicine and the School of Engineering and Applied Science at the University of Pennsylvania, positioning his work is at the nexus of neuroscience and engineering.

One of the first and most impactful grants that Dr. Litt received was from CURE Epilepsy, in 2011 through “Julie’s Hope,” one of three CURE Epilepsy grants funded by Jim and Susan Schneider in honor of their daughter Julie. As a neurologist, Dr. Litt saw first-hand the impact of epilepsy on people’s lives and the lack of options that were available for refractory epilepsies. Back in 2011, the field of implantable devices used standard, rigid clinical electrodes that did not conform to the brain’s surface. Each electrode was connected to a wire, and the device was cumbersome and lent itself to surgical complications and errors. Also, given the large number of wires, it was not possible to effectively cover large areas of the brain. In his project, Dr. Litt wanted to accelerate the development of devices and demonstrate relevance in human epilepsy. Specifically, he worked to develop and refine flexible, active, implantable electrodes to monitor and stimulate the brain with a goal to cure epilepsy. Work done for this grant led to the implantation of these flexible electrodes into experimental animals to record seizures and to stimulate the brain to control seizures.[5]

Over the years, Dr. Litt’s work has led to many other discoveries. Some of the most notable ones are the use of high-resolution, active, flexible surface electrode arrays to distinguish between seizures (“ictal” events) and in-between seizures (“interictal” events). By better visualizing brainwave patterns during these specific times, we can better understand the mechanisms by which seizures begin and discover opportunities for therapeutic interventions to stop them.[6] Another notable area of work is the development of a transparent, graphene-based electrode technology that can simultaneously record brainwaves and perform optical imaging. This innovative approach allows for specificity of the brain recordings coupled with the capacity to visualize the brain regions being recorded. By studying brain activity in this way, we can better understand how the brain processes information which has implications beyond epilepsy.[7]

This work on implantable devices for epilepsy led to a large amount of data. Dr. Litt has been organizing and investigating this ‘big neuro data” by sharing it and collaborating with the international research community, using techniques such as cloud-based platforms and open data ecosystems.[8,9] On a broader level, Dr. Litt’s work with implantable electrodes has also led to the assembly of brain activity data across different epilepsy centers to be combined to create a “map” that may help guide epilepsy surgery.[10] Dr. Litt’s scientific contributions have led him to receive the NIH Director’s Pioneer Award in 2020,[11] awarded to “exceptionally creative scientists proposing pioneering approaches.” His work has also led to several patents.[12,13]

Dr. Litt is also passionate about mentoring scientists. Over the years, has trained over 50 scientists and clinician-engineers.  Two of Dr. Litt’s trainees, Drs. Jonathan Viventi and Flavia Vitale are now established scientists carrying on the work to develop implantable electrodes to understand seizure dynamics and treat epilepsy. Dr. Viventi was awarded the Taking Flight Award by CURE Epilepsy in 2012 and is currently an Assistant Professor in the Department of Biomedical Engineering at Duke University. The focus of Dr. Viventi’s work is to create new technology to understand the workings of the brain at hundreds of times the resolution of current devices. By mapping the brain and its abnormal circuitry, Dr. Viventi hopes to use precision stimulation to stop seizures. His technology consists of thin-film electrode arrays that have hundreds of microelectrodes to precisely map seizure activity in the human brain. This device was tested in nine people with epilepsy, and Dr. Viventi’s team was able to precisely localize the brain areas where seizures were generated. In the future, this technology can be used to plan epilepsy surgery or target brain stimulation.[14]

Dr. Vitale is an Assistant Professor of Neurology at the University of Pennsylvania, and was awarded a Taking Flight Award by CURE Epilepsy in 2017. In this project, she wanted to focus on the concept that seizures begin in a specific region of the brain, the seizure onset zone (SOZ). Brainwaves travel or propagate to surrounding areas, ultimately resulting in seizures. The thought is that to achieve seizure freedom, the SOZ and the surrounding epileptogenic zone must be removed. However, the differentiation of these zones has been challenging using current modalities. Dr. Vitale proposed a technology to precisely map epileptic networks to understand what exact neurons were involved in seizure generation. By using tiny, flexible electrodes that can be independently controlled, she aims to understand seizures at a scale that had never been done before. Building on the work with graphene electrodes with Dr. Litt, Dr. Vitale has developed a technique to accurately map the spread of seizures by using transparent microelectrode arrays.[15] Her team is also working on the next generation of soft electrodes and techniques for safe and precise insertion of electrodes into brain structures.[16]

Thanks to Dr. Litt’s deep interest and investment in training of new scientists, he received the Landis Award for Outstanding Mentorship in 2022.  Through his efforts, Dr. Litt has created a collaborative and nurturing environment in his lab, where trainees are selected not only on scientific merit but also on qualities such as thoughtfulness and real-world experience, and most importantly, the desire to use scientific knowledge for public betterment. Ever the champion of the trainees in his lab, Dr. Litt is actively equipping the next generation of brain scientists in the cross-disciplinary fields of neuroscience, surgery, engineering, computing, electronics, and device development.[17]

In conclusion, the funding that CURE Epilepsy provided to Dr. Litt in 2011 was the beginning of not only his scientific discoveries in the field of implantable devices but also an opportunity to deeply invest in the future and the next generation of scientists. While basic research can take decades to come to fruition, the rewards are great as it helps to build knowledge about how and why the brain generates seizures, and also provides insights into how the brain works in general. By funding basic research for epilepsy devices through Drs. Litt, Viventi, and Vitale, CURE Epilepsy positions the community to find a cure for epilepsy within our lifetime.

 

 

Literature Cited:

  1. Mesraoua B, Deleu D, Kullmann DM, Shetty AK, Boon P, Perucca E, et al. Novel therapies for epilepsy in the pipeline Epilepsy Behav. 2019 Aug;97:282-290.
  2. Verdru J, Van Paesschen W. Wearable seizure detection devices in refractory epilepsy Acta Neurol Belg. 2020 Dec;120:1271-1281.
  3. Esmaeili B, Vieluf S, Dworetzky BA, Reinsberger C. The Potential of Wearable Devices and Mobile Health Applications in the Evaluation and Treatment of Epilepsy Neurol Clin. 2022 Nov;40:729-739.
  4. Litt B. Evaluating devices for treating epilepsy Epilepsia. 2003;44 Suppl 7:30-37.
  5. Viventi J, Kim DH, Vigeland L, Frechette ES, Blanco JA, Kim YS, et al. Flexible, foldable, actively multiplexed, high-density electrode array for mapping brain activity in vivo Nat Neurosci. 2011 Nov 13;14:1599-1605.
  6. Vanleer AC, Blanco JA, Wagenaar JB, Viventi J, Contreras D, Litt B. Millimeter-scale epileptiform spike propagation patterns and their relationship to seizures J Neural Eng. 2016 Apr;13:026015.
  7. Kuzum D, Takano H, Shim E, Reed JC, Juul H, Richardson AG, et al. Transparent and flexible low noise graphene electrodes for simultaneous electrophysiology and neuroimaging Nat Commun. 2014 Oct 20;5:5259.
  8. Wagenaar JB, Worrell GA, Ives Z, Dümpelmann M, Litt B, Schulze-Bonhage A. Collaborating and sharing data in epilepsy research J Clin Neurophysiol. 2015 Jun;32:235-239.
  9. Wiener M, Sommer FT, Ives ZG, Poldrack RA, Litt B. Enabling an Open Data Ecosystem for the Neurosciences Neuron. 2016 Nov 2;92:617-621.
  10. Bernabei JM, Sinha N, Arnold TC, Conrad E, Ong I, Pattnaik AR, et al. Normative intracranial EEG maps epileptogenic tissues in focal epilepsy Brain. 2022 Jun 30;145:1949-1961.
  11. NIH Director’s Pioneer Award Recipients: 2020 Awardees. Available at: https://commonfund.nih.gov/pioneer/AwardRecipients20. Accessed February 7.
  12. Echuaz JR WG, Litt B inventor; Active control of epileptic seizures and diagnosis based on critical systems-like behavior2012.
  13. Vitale F ND, Nicholas A, Litt B, inventor; Rapid manufacturing of absorbent substates for soft, comformable sensors and conductors 2022.
  14. Sun J, Barth K, Qiao S, Chiang CH, Wang C, Rahimpour S, et al. Intraoperative microseizure detection using a high-density micro-electrocorticography electrode array Brain Commun. 2022;4:fcac122.
  15. Driscoll N, Rosch RE, Murphy BB, Ashourvan A, Vishnubhotla R, Dickens OO, et al. Multimodal in vivo recording using transparent graphene microelectrodes illuminates spatiotemporal seizure dynamics at the microscale Commun Biol. 2021 Jan 29;4:136.
  16. Apollo NV, Murphy B, Prezelski K, Driscoll N, Richardson AG, Lucas TH, et al. Gels, jets, mosquitoes, and magnets: a review of implantation strategies for soft neural probes J Neural Eng. 2020 Sep 11;17:041002.
  17. Litt B. Engineering the next generation of brain scientists Neuron. 2015 Apr 8;86:16-20.

CURE Epilepsy Discovery: Funding Basic Mechanisms Research Drives Momentum Toward a CURE

Key Points:

  • For 25 years, CURE Epilepsy has been funding breakthrough research to advance science to find a cure for epilepsy. A key focus of our research grants has been understanding the basic biological mechanisms that result in epilepsy, which provides foundational knowledge that will ultimately lead to a cure for epilepsy.
  • One initiative funded by CURE Epilepsy, the Infantile Spasms (IS) Initiative, brought together a diverse team of medical and scientific experts to rapidly advance IS research and was the first initiative of its kind in the field of epilepsy.
  • John Swann of Baylor College of Medicine, whose work is discussed herein, was one of the grantees involved in the IS Initiative. He has progressed his initial discoveries, demonstrating the importance of funding basic mechanisms research to put us one step closer to a cure.
  • Basic research provides hope for a cure for the epilepsies; by better understanding the mechanisms that cause seizures, we can develop curative treatments for the epilepsies.

 

Deep dive

Twenty-five years ago, CURE Epilepsy was founded finding a cure for epilepsy and related seizure disorders, which now impacts 3.4 million Americans and 65 million people worldwide. The founders saw a need to push the research community to think differently about epilepsy research. This resulted in a paradigm shift for the community, moving from seeking treatments and therapies that would control seizures to focusing on innovative approaches that would advance science and find a cure for epilepsy. Achieving this goal would provide freedom from seizures and the negative side effects of medications. The organization determined that it could have the largest impact by focusing on understanding the basic biological mechanisms underlying the causes of epilepsy. Understanding is the first step in the scientific process, where researchers study the brain to gain a better understanding of why and how seizures are caused. These findings create foundational knowledge that may translate to new ideas to treat epilepsy and eventually preclinical and clinical trials. Clinical trials may ultimately lead to improved and potential cures. Hence, while the benefits of basic epilepsy research are not immediate, the rewards that basic research provides in terms of our understanding epilepsy are unparalleled.

Since 1998, CURE Epilepsy has funded over 280 research grants, and many have addressed the need to learn more about the basic biological mechanisms that underlie epilepsy. Many of these grants have formed the basis for further study, learning, and advancements that may lead us to a cure. One example of this is within infantile spasms (IS), a rare and particularly severe form of epilepsy, with approximately 90% of cases diagnosed in the first year of life. Infantile spasms manifest as sudden, jerking movements of the arms and legs, and are often accompanied by an irregular brainwave pattern on the electroencephalogram (EEG) called hypsarrhythmia.[1]These seizures are also often accompanied by significant cognitive and physical deterioration.[2] Current therapies for IS are effective in only half of the children with IS [3] and are associated with negative side effects, highlighting the need to find better and more effective treatments.

In 2013, CURE Epilepsy launched the Infantile Spasms Initiative, with $4 million in funding. The IS Initiative employed a multi-disciplinary and multi-location team science approach to study the basic biological mechanisms underlying IS, search for biomarkers and novel drug targets, and develop improved treatments. Work done as part of the IS Initiative proved successful across multiple dimensions and led to more than 19 publications. More about the IS Initiative can be found here.[4]

Understanding the basic biological mechanisms underlying IS was a key focus of the IS Initiative. One example of the IS Initiative’s success in understanding a key underlying basic mechanism is from the team led by Dr. John Swann of Baylor College of Medicine.[1] Dr. Swann and his team discovered that treatment with a derivative of the growth hormone insulin-like growth factor 1 (IGF-1) called (1-3) IGF-1 reduced spasms and irregular brain wave patterns on the EEG in an animal model. Adding this compound to vigabatrin, an FDA-approved treatment for IS, reduced the dose of vigabatrin required to eliminate the spasms. Reducing the dosage also decreased the risk of serious side effects, including the potential for irreversible peripheral vision loss. The Swann lab patented this combination treatment and used the discovery to obtain two National Institutes of Health (NIH) grants. The NIH grants enabled Dr. Swann to build on the discoveries from the CURE Epilepsy-funded IS Initiative. In a subsequent study, data from Dr. Swann’s team revealed that the levels IGF-1 itself were lower in brain tissue from both a rat model and from infants with IS. Data also indicated that reduced expression of IGF-1 in the rat model affected the biological pathways critical for neurodevelopmental processes.[6]

Using the learnings from the IS Initiative as a foundation, through a series of additional experiments, the team confirmed that the (1-3) IGF-1 could also cross the blood-brain barrier with much higher efficiency than the full-length IGF-1 and activate the same biological pathways as full-length IGF-1.[7] The researchers administered it to the rats in their experiment, and successfully eliminated both the spasms and the hypsarrhythmia in most rodents. This exciting finding suggests that this smaller (1-3) IGF-1 or perhaps an IGF-1-like drug may one day be used to treat IS patients immediately after the condition is diagnosed. You can read more about this study here.

Dr. Swann and his team have continued to build on the learnings initially funded through their CURE Epilepsy grant; recently, the team studied seizure progression in IS, and the impact of spasms on learning and memory.[8] Infants with IS show developmental delay and behavioral abnormalities, with only 16% of patients with IS exhibiting normal intellectual development.[9] The reasons for a delay in intellectual development could be many, though they have not yet been determined.[10,11] Additionally, the trajectory of the decline in intellectual and behavioral abilities has not yet been documented due to the variability of the condition, and limitations in assessing intellectual abilities in infants. Spasms can be subtle, making an accurate diagnosis of the exact start of the spasms challenging.[12] Hence, whether the behavioral decline is caused by or simply associated in time with seizures in IS is an area where more research is necessary. Given the difficulties of understanding this relationship between seizures and cognitive decline in infants with IS, Dr. Swann’s team used rats with a history of spasms and assessed them in a series of tests to gauge their ability to learn and remember. Swann’s team used rats with a history of spasms and assessed them in a series of memory tests to gauge their ability to learn and remember. The team also studied their brainwaves using EEG.

Previous work by Dr. Swann’s team had developed a model to simulate IS in animal models.[13] In this model, a substance known as tetrodotoxin (TTX) is infused into the brains of infant rats 10-12 days after birth which causes many of the characteristics of IS, including spasms, seen in humans.[13] The research team then used tests to examine spatial and working memory. Spatial memory helps us remember locations and the relationship between locations, and working memory helps us remember a small part of the information in our minds temporarily. To better understand the brainwaves in rats that had spasms, Dr. Swann’s team performed continuous EEG recordings for a total of seven weeks after infusion of TTX.[8] Rats with spasms were compared with rats that did not have spasms. After seven weeks of EEG recording, behavioral tests were done to test learning and memory. The study showed that rats experiencing spasms showed impairment on the behavioral tests, pointing to issues in learning and memory, which are also seen in infants with IS.[8] EEG analysis showed that there was an increase in spasms for two weeks, and after the two weeks, spasms stabilized.[8] Seizure progression in epilepsy has long been a topic of intense research. The current study suggests that like other seizure disorders[14,15], there may be a critical period in IS when there is a gradual increase in spasm intensity over time. A better understanding of seizure progression patterns in IS could lead to clues about therapies, management, and prognosis. This work from Dr. Swann’s lab is unique as the team did rigorous EEG monitoring and behavioral analysis; these techniques are time and labor-intensive, and seizures in IS have not been studied this deeply before.[8] The neurological mechanisms that underlie memory disturbances and seizure progression in IS are not fully known. So, seizures could be correlated with the learning deficits, but exact details are not clear. Additional research using EEG monitoring coupled with behavioral analysis in the same animals could provide clarity into the relationship.

In conclusion, basic research provides a foundational understanding of underlying biology of a disease process from which cures for the epilepsies will be found. CURE Epilepsy has been funding basic research for 25 years with the sole mission of finding a cure for epilepsy. Dr. Swann’s work as part of the IS Initiative is one example of how strategic, long-term investment in basic research can advance our knowledge by leaps and bounds.

 

 

Literature Cited:

  1. Gibbs EL, Fleming MM, Gibbs FA. Diagnosis and prognosis of hypsarhythmia and infantile spasms Pediatrics. 1954 Jan;13:66-73.
  2. Cowan LD, Hudson LS. The epidemiology and natural history of infantile spasms J Child Neurol. 1991 Oct;6:355-364.
  3. Knupp KG, Coryell J, Nickels KC, Ryan N, Leister E, Loddenkemper T, et al. Response to treatment in a prospective national infantile spasms cohort Ann Neurol. 2016 Mar;79:475-484.
  4. Lubbers L, Iyengar SS. A team science approach to discover novel targets for infantile spasms (IS). Epilepsia Open. 2021;6:49-61.
  5. Swann J, Lee, CL., Le, JT. and Frost Jr, JD. , inventor; Combination therapies for treating infantile spasms and other treatment resistant epilepsies 2022.
  6. Ballester-Rosado CJ, Le JT, Lam TT, Mohila CA, Lam S, Anderson AE, et al. A Role for Insulin-like Growth Factor 1 in the Generation of Epileptic Spasms in a murine model Ann Neurol. 2022 Jul;92:45-60.
  7. Yamamoto H, Murphy LJ. Enzymatic conversion of IGF-I to des(1-3)IGF-I in rat serum and tissues: a further potential site of growth hormone regulation of IGF-I action J Endocrinol. 1995 Jul;146:141-148.
  8. Le JT, Ballester-Rosado CJ, Frost JD, Jr., Swann JW. Neurobehavioral deficits and a progressive ictogenesis in the tetrodotoxin model of epileptic spasms Epilepsia. 2022 Dec;63:3078-3089.
  9. Hrachovy RA, Frost JD, Jr. Infantile epileptic encephalopathy with hypsarrhythmia (infantile spasms/West syndrome) J Clin Neurophysiol. 2003 Nov-Dec;20:408-425.
  10. Wirrell EC, Shellhaas RA, Joshi C, Keator C, Kumar S, Mitchell WG. How should children with West syndrome be efficiently and accurately investigated? Results from the National Infantile Spasms Consortium Epilepsia. 2015 Apr;56:617-625.
  11. Osborne JP, Lux AL, Edwards SW, Hancock E, Johnson AL, Kennedy CR, et al. The underlying etiology of infantile spasms (West syndrome): information from the United Kingdom Infantile Spasms Study (UKISS) on contemporary causes and their classification Epilepsia. 2010 Oct;51:2168-2174.
  12. Lux AL, Osborne JP. A proposal for case definitions and outcome measures in studies of infantile spasms and West syndrome: consensus statement of the West Delphi group Epilepsia. 2004 Nov;45:1416-1428.
  13. Lee CL, Frost JD, Jr., Swann JW, Hrachovy RA. A new animal model of infantile spasms with unprovoked persistent seizures Epilepsia. 2008 Feb;49:298-307.
  14. Jeavons PM, Bower BD. The natural history of infantile spasms Arch Dis Child. 1961 Feb;36:17-22.
  15. Golomb MR, Garg BP, Williams LS. Outcomes of children with infantile spasms after perinatal stroke Pediatr Neurol. 2006 Apr;34:291-295.

CURE Epilepsy Discovery: A Look Into the Journeys of CURE Epilepsy Taking Flight Grantees

Key Points:

  • CURE Epilepsy is the leading non-profit organization focused on funding research to find cures for epilepsy.
  • To achieve our mission, CURE Epilepsy created grant mechanisms to support research to understand the basic biological mechanisms or foundations of what causes seizures that become epilepsy as well as awards for pre-clinical research and more.
  • The Taking Flight Award was created to support epilepsy investigators early in their careers to develop a research focus separate from their mentor’s.
  • This Discovery highlights three Taking Flight awardees who received grants for diverse projects, ranging from work on sudden unexpected death in epilepsy (SUDEP) to mapping epileptic brain networks, to an exploration of circadian function as a potential mechanism and a therapeutic target for epilepsy.
  • The three awardees are Dr. William Nobis from Vanderbilt University Medical Center, Dr. Flavia Vitale from The University of Pennsylvania, and Dr. Cristina Reschke at the Royal College of Surgeons in Ireland. These awardees share their motivations for pursuing epilepsy research as a career, the importance of the CURE Epilepsy Taking Flight in their careers, and the impact they hope to have in the epilepsy community.

Deep dive

Epilepsy is one of the most common neurological disorders and affects 65 million people worldwide [1] and 3.4 million Americans [2]. Epilepsy can impact a person at any point in their lifetime, regardless of age, demographics, race, or socioeconomics. Those who live with epilepsy can face a lifetime of challenges. CURE Epilepsy’s mission is to find a cure for epilepsy, by promoting and funding patient-focused research, CURE Epilepsy has developed a variety of granting mechanisms [3], including the Taking Flight Award.[4] This one-year, $100,000 grant is meant to fund studies that will provide new insights into epilepsy, its prevention, and cures. An additional goal of the Taking Flight Award is to foster scientific independence of early career investigators and provide them with the means to collect the necessary data to apply for subsequent funding, thus further advancing their career in epilepsy research.[4]

Through 2021, CURE Epilepsy has funded 48 early career scientists through the Taking Flight Award, supporting them on their path to research independence. Recently, we spoke with three Taking Flight awardees about their research, the impact that receiving the Taking Flight Award had on their research and their vision for the future of their research. The three awardees and their projects were: Dr. William Nobis at Vanderbilt University Medical Center who studied a part of the brain called the amygdala and its role in sudden unexpected death in epilepsy (SUDEP); Dr. Flavia Vitale at The University of Pennsylvania who explored a technique to accurately map epileptic brain networks; and Dr. Cristina Reschke at the Royal College of Surgeons in Ireland, who examined the role of the circadian function in epilepsy.

The awardees noted varying inspirations to pursue the field of epilepsy research. For example, Dr. Nobis mentioned, “I have always been interested in neuroscience research, my initial motivation for training to be a physician-scientist was my experience with my grandmother and Alzheimer’s disease. During my residency training in neurology, I had exposure to epilepsy patients and experience with epileptologists, and I liked the impact you could have on patients’ lives by controlling seizures.” Dr. Nobis continues to be inspired by the patients he aims to serve. He says, “I want to do research that has the opportunity to make an impact on my patients’ lives – this is something that is within reach for epilepsy researchers. We have come far with controlling epilepsy but there are still so many people impacted by seizures.

Controlling epilepsy and preventing SUDEP are both interesting problems that will involve cutting edge circuit-based science and are also of immense importance and impact for the lives of our patients.” Previous research on SUDEP had shown that difficulties in breathing (respiratory depression) could lead to deficits in heart function, ultimately leading to death.[3] To understand this process better, Dr. Nobis’ team analyzed intracranial electroencephalograph (EEG), i.e., electrical signals from deep within the brain, and combined this with the measurement of breathing.[4] They found a specific role of the amygdala and the brainstem in respiratory depression during seizures. The discovery that this circuit may play a role in SUDEP means that in the future, we may be able to target it with interventions to prevent SUDEP.

According to Dr. Nobis, the Taking Flight Award gave him the capability to commit full-time to the SUDEP research, which had been a side project that he was working on in his mentor’s lab. He was able to publish his studies and take the next step in his career by accepting a position at Vanderbilt University Medical Center.[5] Subsequent mentored career-development awards helped him launch his research program centered on the physiological mechanisms of SUDEP. Looking into the future, Dr. Nobis commended the epilepsy research community with these words, “I love the epilepsy research community; I have not been around a group of more earnest and supportive group of scientists that are dedicated to improving the treatment of epilepsy patients. To do something that will improve the lives of epilepsy patients and work towards the goal of no SUDEP, no seizures, and no side effects.”

The basis for Dr. Vitale’s research is the premise that epilepsy arises from disrupted brain networks. To properly treat seizure-related conditions, it is important to map these networks as precisely as possible, but current methods of mapping epileptic neuronal networks do not provide the fine level of detail that is necessary. As part of Dr. Vitale’s Taking Flight research project, she developed miniature, flexible electrodes that could be controlled independently after they were implanted in the brain.[10] This technology has already shown success in detecting seizures in mice [6,7], and it is envisioned that this work of detecting seizure activity in experimental animals could ultimately lead to technologies to map epileptic networks in patients in a highly precise manner.

Speaking to her motivation, Dr. Vitale, was interested in joining a multidisciplinary team that “brings together engineers, clinicians, and neuroscientists to develop novel technological and therapeutic approaches to understand, diagnose, and treat neurological disorders, and in particular epilepsy.” Dr. Vitale found that working closely with clinicians and surgeons whose mission is to fight epilepsy, made her realize how engineers developing new devices, algorithms, modeling, and analysis tools can play a key role in supporting clinicians in their decision-making and provide them with more accurate and effective tools to diagnose and treat their patients. She also mentioned that the personal stories from patients and families reinforced her decision to start a career in neuro-engineering for epilepsy research.

Dr. Vitale describes the Taking Flight Award as an “inflection point” in her career, as the award enabled her to start her lab at the University of Pennsylvania.[8] In her words, “this award jumpstarted my research program in epilepsy research and helped me to gather key preliminary data that later supported successful grant applications and publications. Finally, the award provided recognition among the epilepsy research community and helped me establish new fruitful collaborations.” She summarizes her views on epilepsy research as, “Our mission is to ultimately translate our findings and technological innovations to patients. With more precise and safer electrodes, it will be easier to find and remove the areas of the brain where seizures originate, which has been shown to improve seizure-free rates. We are also developing easier-to-use, portable, and low-cost non-invasive brain monitoring systems to improve access and quality epilepsy care in low-resource settings and for at-home monitoring. Such technologies will offer more accurate data for diagnosis and therapy and reduce the burden of travel to patients in remote areas.”

Dr. Reschke’s work focuses on how circadian rhythms may impact epilepsy.[9,11] Previous studies have hypothesized a link between epilepsy and the 24-hour biological rhythms present in humans that are called “circadian rhythms.”[12] Dr. Reschke’s award, funded by The Cameron Boyce Foundation, aims to explore whether the mechanisms that control circadian rhythms are involved in the process of epileptogenesis (the process by which a non-epileptic circuit is transformed into an epileptic circuit). She will also develop a gene therapy approach in mice to see whether restoring a gene involved in circadian rhythms can halt epileptogenesis.[9,11] 

Dr. Reschke emphasized the excitement of discovery and the patient-centeredness of research as two main reasons she was attracted to working in epilepsy. “If we understand a bit more about the brain, we can develop focused and tailored approaches to epilepsy and accompanying comorbidities.” To her, while the science and research are extremely interesting, the possibility of impacting people with epilepsy, “makes the long hours worthwhile.”

Dr. Reschke also found her independence as a researcher thanks to the Taking Flight Award. The award allowed her to obtain, first, a temporary, and later, a permanent position at the Royal College of Surgeons in Ireland. She was able to secure lab space and personnel to do the work. The Taking Flight Award, in her words, “was extremely important and instrumental in establishing my career in epilepsy in academia.” In addition to the support for research, the award also gave her international recognition and helped her enhance her professional networks. Leveraging her research, recognition, and networks, Dr. Reschke is heavily involved in advocacy and education as well. She feels that “communicating research to patients’ families and caregivers is crucial,” and she feels that it is critical to put her clinical work into practice. She is also passionate about educating the next generation of epilepsy researchers by promoting training and fellowships to give them, “the opportunities that I have; to give them a chance to work on research that is deeply meaningful.”

The Taking Flight Awards have deeply impacted the grantees, and through them, numerous people that are affected by epilepsy every day. Awardees cited the capacity to contribute to scientific excellence while having a positive impact on patients with epilepsy and their caregivers as the most rewarding aspect of the award. The money granted by CURE Epilepsy to the researchers to gain scientific independence, develop new techniques, and discover novel mechanisms of epileptogenesis will help the organization achieve our goal of a world without epilepsy.

 

Literature Cited:

  1. Ngugi AK, Bottomley C, Kleinschmidt I, Sander JW, Newton CR. Estimation of the burden of active and lifetime epilepsy: a meta-analytic approach Epilepsia. 2010 May;51:883-890.
  2. National and State Estimates of the Numbers of Adults and Children with Active Epilepsy — United States, 2015.
  3. CURE Epilepsy: Grant Opportunities Available at: https://cureepilepsy.org/grants-program/. Accessed November 11
  4. CURE Epilepsy Taking Flight award Available at: https://cureepilepsy.org/wp-content/uploads/2022/10/2023-Taking-Flight-Award-LOI-Full-Propsal-Guidelines.pdf. Accessed November 11
  5. Ryvlin P, Nashef L, Lhatoo SD, Bateman LM, Bird J, Bleasel A, et al. Incidence and mechanisms of cardiorespiratory arrests in epilepsy monitoring units (MORTEMUS): a retrospective study Lancet Neurol. 2013 Oct;12:966-977.
  6. Nobis WP, González Otárula KA, Templer JW, Gerard EE, VanHaerents S, Lane G, et al. The effect of seizure spread to the amygdala on respiration and onset of ictal central apnea J Neurosurg. 2019 Apr 5;132:1313-1323.
  7. Department of Neurology; William P. Nobis, MD, Ph.D. Available at: https://www.vumc.org/neurology/person/william-p-nobis-md-phd. Accessed November 11
  8. Mulcahey PJ, Chen Y, Driscoll N, Murphy BB, Dickens OO, Johnson ATC, et al. Multimodal, Multiscale Insights into Hippocampal Seizures Enabled by Transparent, Graphene-Based Microelectrode Arrays eNeuro. 2022 May-Jun;9.
  9. Driscoll N, Rosch RE, Murphy BB, Ashourvan A, Vishnubhotla R, Dickens OO, et al. Multimodal in vivo recording using transparent graphene microelectrodes illuminates spatiotemporal seizure dynamics at the microscale Commun Biol. 2021 Jan 29;4:136.
  10. Flavia Vitale, Ph.D.; Penn Medicine Available at: https://www.med.upenn.edu/apps/faculty/index.php/g324/p8887287. Accessed November 11
  11. Restoration of Circadian Function as a Novel Therapy for Epilepsy. Available at: https://cureepilepsy.org/grant_type/restoration-of-circadian-function-as-a-novel-therapy-for-epilepsy/. Accessed November 11.
  12. Jin B, Aung T, Geng Y, Wang S. Epilepsy and Its Interaction With Sleep and Circadian Rhythm Front Neurol. 2020;11:327.

CURE Epilepsy Discovery: CURE Epilepsy Grantees Explore Genetic Determinants of Sudden Unexpected Death in Pediatrics (SUDP)

Key Points:

  • Sudden infant death syndrome (SIDS), sudden unexpected infant death (SUID), and sudden unexplained death in childhood (SUDC) are tragic conditions referring to the unexplained death of an infant or child. While previously thought of as separate entities, evidence suggests that there is an overlap between these conditions and that they may be considered under the overarching umbrella of sudden unexpected death in pediatrics (SUDP).
  • A previous study awarded by CURE Epilepsy and made possible by funding from the Isaiah Stone Foundation to Dr. Annapurna Poduri and colleagues suggested that genes associated with epilepsy may be involved in SUDP.[1]
  • A new study*, which was an outgrowth of the earlier CURE Epilepsy funded research, included 352 SUDP cases and employed state-of-the-art genetic techniques, in-depth analysis of family history and circumstances of death, and analysis of parental genetic information as well.[2]
  • The study showed evidence for genetic factors that may play a role in SUDP; while some genes were already potentially associated with sudden death in children, several variants in genes previously not associated with SUDP were identified.
  • In addition to providing genetic information about SUDP, the group’s work is proof of concept that a multidisciplinary lens to study SUDP is not only feasible, but necessary to advance the field.

 

Deep dive

The sudden death of a child is a tragic occurrence. Of all the child and infant deaths in the United States, more than 10% occur without any apparent cause, compounding the grief of families who have lost their children.[3] These sudden, unexpected deaths typically impact seemingly healthy children and are classified as sudden infant death syndrome (SIDS), sudden unexpected infant death (SUID), or sudden unexplained death in childhood (SUDC). Together, these three entities are thought of as sudden unexpected death in pediatrics (SUDP).[4] Through the generous support of the Isaiah Stone Foundation, CURE Epilepsy funded Dr. Annapurna Poduri and colleagues Rick Goldstein, Hannah Kinney, and Ingrid Holm in Robert’s Program** at Boston Children’s Hospital to explore the genetic basis of SUDP; the hypothesis for this work is that there are common, underlying, genetic mechanisms behind the three entities of sudden childhood death, epilepsy and sudden unexpected death in epilepsy (SUDEP).

Earlier work from these researchers had highlighted a link between SIDS and variants in a gene called SCN1A, which is associated with epilepsy and SUDEP.[1, 5, 6] What was notable is that while this gene is traditionally thought to be related to epilepsy, the children who died suddenly and unexpectedly had no history of seizures or epilepsy. This and other studies have suggested that SUDP is an overarching disorder consisting of rare and yet-undiagnosed diseases with potentially overlapping genetic mechanisms.[1, 7, 8]

To build on the previous work supported by CURE Epilepsy, Dr. Poduri and colleagues conducted a larger, more extensive study* to explore genetic risk factors for SUDP.[2] The ultimate goal was to find more accurate ways of diagnosing children at risk of sudden death and eventually prevent such incidences. The current study led by Dr. Poduri and her colleagues Drs. Hyunyong Koh and Alireza Haghighi included 352 SUDP cases.[2] This study looked at “trio-based” cohorts; meaning they studied the child and the child’s parents. This is a stronger approach to studying genetic contributions to a disease process, especially for SUDP, where a genetic link is suspected.[9, 10] Additionally, since the mechanisms underlying SUDP are complex and not yet fully known, the team took a “multidisciplinary undiagnosed diseases approach”[11] that combined genetic analysis, autopsy data, and in-depth study of the child’s phenotype (or observable characteristics). Parents agreed to all analyses performed. 

The genetic analysis included a candidate-gene approach where scientists have some information to suggest that a certain gene may be associated with a certain disease. In this case, 294 genes plausibly related to SUDP, called SUDP genes were studied, many of which were associated with neurologic disorders, cardiac disorders, or systemic/syndromic conditions. [12, 13] Systemic conditions and associated genes affect the entire body, and syndromic conditions include genes for metabolism and those responsible for the functioning of multiple body systems. The team performed a genetic technique called exome sequencing, where the parts of genes that eventually become functional proteins were analyzed for variants that may have caused or contributed to sudden death.[2]

The multidisciplinary team at Robert’s Program on SUDP, directed by Dr. Rick Goldstein, characterized fully the conditions surrounding the death of the child, performed an in-depth analysis of the child’s medical and family history, and conducted exome sequencing. The study showed that SUDP was associated with specific genetic factors, some of which were previously known, but many of which were novel. Detailed analysis showed that the majority of the children were between two and six months old, and 57% were male. Out of the 352 cases, death was associated with sleep in an overwhelming majority (346 children).[2] Genetic analysis revealed variants in genes related to cardiac disease, neurologic diseases, and systemic/syndromic diseases. Most variants were de novo, or new, while some were inherited. Burden analysis, in which the trios were compared to controls, showed that there were more SUDP trio cases with rare, damaging de novo variants as compared to controls. There were also clues as to the presence of febrile seizures, a family history of SIDS or SUDC, and a family history of epilepsy and cardiac disease in several cases. When the genes implicated in SUDP were classified by the age of death of the child, a pattern emerged. Specifically, variants in neurological and syndromic genes appeared in the age ranges associated with SIDS (the child being less than one year old) and SUDC (the child is greater than one year old), and variants in cardiac genes were preferentially seen only in the earlier age range, i.e., associated with SIDS.[2]

Overall, the study found that there was a genetic contribution to SUDP in 11% of the cases and suggests that these genetic variants may increase susceptibility to sudden death. Many genes that were previously not linked with SUDP were able to be reclassified as being associated with SUDP. The power of this study is that the genes for SUDP that were investigated were not the ones previously examined. A few specific genes found to be implicated in SUDP are SCN1A and DEPDC5, which have also been shown to be relevant in SUDEP. Other genes were associated with cardiac issues such as arrhythmia and cardiomyopathy (a condition that makes it harder for the heart to pump blood).[2]

The study also shows the importance of looking at trio data, as in this case, it led to the reclassification of several genetic variants. SUDP is a particularly difficult condition to study because unfortunately, a genetic condition may never have been diagnosed or suspected. Hence, the trio approach was instrumental in the success of the current study. The study also adds to evidence [7, 8] that conditions such as stillbirth, SIDS, and SUDC are not separate entities, but represent a continuum of events associated with unexplained death from fetal life to childhood.[14] It is possible and even likely that there are overlapping genetic variants (SCN1A being one) common to these conditions. Notably, another study from a different group also performed genetic analysis from trios and found de novo mutations associated with sudden unexplained death in childhood.[15]

Future studies will look at more trio data and an even more detailed genetic analysis. While many genetic risk factors were found in the current study, it does not mean that they were necessarily the cause of death; more work will be needed to look at specific neurologic mechanisms. In addition to the scientific findings, the study also sets the scene for a model where a multidisciplinary team engages with parents who have lost their children to unexplained death. In addition to providing scientific answers, a multidisciplinary team also can help provide counseling for family members at a much-needed time.

 

Footnotes:

*Supported by funds from the Robert’s Program on Sudden Unexpected Death in Pediatrics, the Cooper Trewin Memorial SUDC Research Fund, CURE Epilepsy through the Isaiah Stone Foundation Award, Three Butterflies SIDS Foundation, The Florida SIDS Alliance, Borrowed Time 151, and The Eunice Kennedy Shriver National Institute of Child Health and Human Development under grant numbers R21 HD096355 and R01 HD090064.

**Robert’s Program at Boston Children‘s Hospital provides comprehensive clinical care to those that have lost a child suddenly and unexpectedly and performs research to better understand SUDP.

 

Literature Cited:

  1.      Brownstein CA, Goldstein RD, Thompson CH, Haynes RL, Giles E, Sheidley B, et al. SCN1A variants associated with sudden infant death syndrome Epilepsia. 2018 Apr;59:e56-e62.
  2.      Koh HY, Haghighi A, Keywan C, Alexandrescu S, Plews-Ogan E, Haas EA, et al. Genetic Determinants of Sudden Unexpected Death in Pediatrics Genet Med. 2022 Apr;24:839-850.
  3.      About Underlying Cause of Death, 1999-2020. Available at: https://wonder.cdc.gov/ucd-icd10.html. Accessed October 4.
  4.     Goldstein RD, Nields HM, Kinney HC. A New Approach to the Investigation of Sudden Unexpected Death Pediatrics. 2017 Aug;140.  
  5.     Escayg A, Goldin AL. Sodium channel SCN1A and epilepsy: mutations and mechanisms Epilepsia. 2010 Sep;51:1650-1658.
  6.    Goldman AM. Mechanisms of sudden unexplained death in epilepsy Curr Opin Neurol. 2015 Apr;28:166-174.
  7.    Perrone S, Lembo C, Moretti S, Prezioso G, Buonocore G, Toscani G, et al. Sudden Infant Death Syndrome: Beyond Risk Factors Life (Basel). 2021 Feb 26;11.
  8.    Weese-Mayer DE, Ackerman MJ, Marazita ML, Berry-Kravis EM. Sudden Infant Death Syndrome: review of implicated genetic factors Am J Med Genet A. 2007 Apr 15;143a:771-788.
  9.    Richards S, Aziz N, Bale S, Bick D, Das S, Gastier-Foster J, et al. Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology Genet Med. 2015 May;17:405-424.
  10.   Rehm HL. A new era in the interpretation of human genomic variation Genet Med. 2017 Oct;19:1092-1095.
  11.   MacNamara EF, D’Souza P, Tifft CJ. The undiagnosed diseases program: Approach to diagnosis Transl Sci Rare Dis. 2020 Apr 13;4:179-188.
  12.   An Online Catalog of Human Genes and Genetic Disorders (OMIM). Available at: https://www.omim.org/. Accessed October 4.
  13.   The Human Gene Mutation Database (HGMD®). Available at: https://www.hgmd.cf.ac.uk/ac/index.php. Accessed October 4.
  14.   Goldstein RD, Kinney HC, Willinger M. Sudden Unexpected Death in Fetal Life Through Early Childhood Pediatrics. 2016 Jun;137.
  15.   Halvorsen M, Gould L, Wang X, Grant G, Moya R, Rabin R, et al. De novo mutations in childhood cases of sudden unexplained death that disrupt intracellular Ca(2+) regulation Proc Natl Acad Sci U S A. 2021 Dec 28;118.

CURE Epilepsy Discovery: Brain Aging in Childhood-Onset Epilepsy: A Long-Term, Population-Based Study

Key Points:

  • Little is known about how the brain and brain function change with aging in older people with epilepsy, particularly among those with childhood-onset epilepsy (COE).
  • CURE Epilepsy funded Dr. Bruce Hermann (University of Wisconsin, United States) and Dr. Matti Sillanpää (University of Turku, Finland) to study the intersection of epilepsy and aging in a unique population-based group of people with epilepsy [1]. This group of people, whom Dr. Sillanpää had been following over decades, consists of persons diagnosed with COE when they were less than 16 years old (4.6 years of age on average).
  • The current study examined these individuals 55 years after the initial epilepsy diagnosis. Individuals with COE showed signs of brain aging that in several respects were more accelerated than those without epilepsy. Additionally, specific risk factors predictive of problematic brain aging outcomes were identified.  
  •  If confirmed with a larger group of people, these data could impact epilepsy treatment and our understanding of how epilepsy and aging overlap.

 

Deep Dive:

Studies in the general population have shown that the aging process changes brain functioning and cognition [2] and there is now much interest in discovering ways to protect the brain and cognition with aging. Through multiple grants funded by CURE Epilepsy including a CURE Innovator Award, a CURE  Epilepsy Award, and an Epilepsy Research Continuity Fund Award, Drs. Bruce Hermann at the University of Wisconsin and Matti Sillanpää at the University of Turku studied a unique patient population of individuals with childhood-onset epilepsy (COE) to investigate neurological and cognitive outcomes 55 years after the initial diagnosis [1].

Earlier studies with this same group (at 50 years after the initial diagnosis) showed that while seizure outcomes in this population were excellent, subsets of people with COE showed some signs of possible neurological and cognitive decline [3, 4]. However, the apparent declines could have been due to multiple factors including epilepsy, aging that was intensified by epilepsy, or simply longstanding abnormalities independent of aging. To get further clarity, Drs. Hermann and Sillanpää recruited many of the same individuals five years after the previous study (i.e., 55 years after the initial diagnosis) [1] to describe the seizure and neurological status of this population and identify the prospective changes at 55 years post-initial diagnosis by comparison to their status at 50 years post-initial diagnosis [4].

The study population, developed by Dr. Sillanpää, consisted of people in Turku, Finland who were diagnosed with active epilepsy between 1961 – 1964 when they were less than 16 years old. The initial population consisted of 245 people of which approximately 100 had epilepsy without other initial neurologic impairments, who were the focus of this investigation [3, 5]. The study performed 50 years after the initial diagnosis consisted of 51 subjects with COE and 52 non-epilepsy controls [4], and the current study at 55 years had complete data sets for 37 subjects with COE and 39 controls [1]. The following outcomes were examined in people with COE and controls:

  1.     clinical neurological signs including but not limited to consciousness, behavior, orientation, reflexes, and sensory functions.
  2.     magnetic resonance imaging (MRI) abnormalities in the brain identified on structured clinical review.
  3.     non-neurologic disorders such as high blood pressure, hypercholesteremia, and obesity.

The rationale for examining non-neurologic outcomes was based on previous studies that have shown a link between epilepsy and obesity [6], and between elevated cholesterol and triglycerides and epilepsy [7], and their roles in the brain aging process remained to be determined. As part of neurologic outcomes, an area of the brain called the cerebellum was also examined since abnormalities in this area have long been documented in epilepsy but are poorly understood [8]. The presence of seizures and their types were also assessed. Additionally, the dose of four commonly prescribed antiseizure medications (ASMs) was assessed to calculate lifelong ASM doses, and associations between ASMs and biological parameters were assessed.

In the current cohort, the average age of the participants was 63.2 years for the COE group and 63.0 years for the control group. A quarter of individuals with COE had active epilepsy and the rest were seizure-free for 10 years or more. Subjects with COE that had active epilepsy had more severe neurologic changes in general, and cerebellar abnormalities specifically. This is important because while the role of the cerebellum in epilepsy has been documented [8], it remains unclear whether abnormalities in the cerebellum are a cause for seizures, a consequence of seizures or their treatment, or purely coincidental. In this study, subjects with COE did not originally have cerebellar abnormalities, suggesting that changes are related to ongoing epilepsy and/or medical treatment [9]. Data analyses also revealed other interesting associations including that a high lifetime dose of ASMs was correlated with an increase in neurologic changes, and there was a link between peripheral neuropathy (damage of nerves outside the central nervous system) and use of ASMs. Another significant association that was noted was a decreased volume of a part of the brain called the hippocampus as seen on MRI and high arterial hypertension (vs. normal blood pressure) in people with COE. In addition, high cholesterol was more prevalent in people with focal epilepsy as compared to generalized epilepsy [4]. When the entire cohort (those with COE and controls) was compared to earlier results at 50 years post-initial diagnoses, the authors found that overall, more people exhibited neurologic changes at the 55-year follow-up [4].

In conclusion, when examined decades after diagnosis, adults with COE who continue to have active epilepsy appear to have an accelerated tendency towards brain aging as compared to controls. The study provides a unique and exceptionally long-term perspective on the intersection of aging and epilepsy. This is also the first study to explore changes in the brain through MRI and neurologic functioning in individuals with COE as compared to controls. Additional findings to follow from this investigation will address prospective quantitative MRI changes, biomarkers of abnormal aging, and prospective cognitive trajectories over the five years. While results from the current study will need to be confirmed, it has the potential to impact the treatment of epilepsy and change the way we think of the intersection of epilepsy and aging.

 

Literature Cited:

  1.       Sillanpää M, Hermann B, Rinne JO, Parkkola R, Saarinen MM, Karrasch M, et al. Differences in brain changes between adults with childhood-onset epilepsy and controls: A prospective population-based study Acta Neurol Scand. 2022 Mar;145:322-331.
  2.       How the aging brain affects thinking Available at: https://www.nia.nih.gov/health/how-aging-brain-affects-thinking. Accessed September 5.
  3.       Sillanpää M. Medico-social prognosis of children with epilepsy. Epidemiological study and analysis of 245 patients Acta Paediatr Scand Suppl. 1973;237:3-104.
  4.       Sillanpää M, Anttinen A, Rinne JO, Joutsa J, Sonninen P, Erkinjuntti M, et al. Childhood-onset epilepsy five decades later. A prospective population-based cohort study Epilepsia. 2015 Nov;56:1774-1783.
  5.       Sillanpää M, Jalava M, Kaleva O, Shinnar S. Long-Term Prognosis of Seizures with Onset in Childhood New England Journal of Medicine. 1998;338:1715-1722.
  6.       Ladino LD, Téllez-Zenteno JF. Chapter 7 – Epilepsy and obesity: A complex interaction. In: Mula M, editor. The Comorbidities of Epilepsy: Academic Press; 2019. p. 131-158.
  7.       Harnod T, Chen HJ, Li TC, Sung FC, Kao CH. A high risk of hyperlipidemia in epilepsy patients: a nationwide population-based cohort study Ann Epidemiol. 2014 Dec;24:910-914.
  8.       Streng ML, Krook-Magnuson E. The cerebellum and epilepsy Epilepsy & Behavior. 2021 2021/08/01/;121:106909.
  9.       Hagemann G, Lemieux L, Free SL, Krakow K, Everitt AD, Kendall BE, et al. Cerebellar volumes in newly diagnosed and chronic epilepsy J Neurol. 2002 Dec;249:1651-1658.

CURE Epilepsy Discovery: Developing Precision Medicine Treatments for Genetic Epilepsies: Present Challenges, Recent Scientific Advances, and Future Prospects

Key Points:

  • Epilepsy is a serious neurological disorder with many possible causes, and those directly linked to genetic abnormalities have undergone significant scientific breakthroughs in recent years.
  • Precision medicine is “an emerging approach for disease treatment and prevention that takes into account individual variability in genes, environment, and lifestyle for each person”. This concept is being applied to genetic epilepsies, but significant challenges have limited the rate at which basic science has translated into new treatments.
  • New strategies and scientific techniques may hasten the process. A recent publication in Epilepsia highlights some of them, along with the basic science that has fostered the hope for the eventual realization of precision medicine [1]. The authors suggest that greater coordination of efforts by scientists, physicians, patient advocates, and the federal government will accelerate effective, ethical, and equitable precision medicine for genetic epilepsy.
  • This publication stems from discussions at the Epilepsy Precision Medicine conference, funded in part by CURE Epilepsy and held in Washington, DC in 2019. This conference brought together the many stakeholders involved in developing precision therapies for epilepsy including researchers, physicians, funding agencies, and people with lived experience to share their experiences of epilepsy. The publication’s writing team was led by recent CURE Epilepsy Taking Flight grantee Juliet Knowles, MD, PhD.

 

Deep Dive:

Epilepsy is a debilitating but surprisingly common neurological disorder, with 1 in 26 people in the United States developing it over the course of their lives [2]. Despite the availability of numerous antiseizure medications (ASMs), one-third of people with epilepsy have seizures that remain treatment-resistant [3]. There are many possible causes of epilepsy, ranging from traumatic brain injuries to specific genetic mutations. Regardless of the cause, treatment remains primarily empirical or based on observation, with patients and their epileptologists often trying different and multiple ASMs in an attempt to eliminate the seizures while managing unwanted side effects. Ideally, treatments for epilepsy would precisely target the underlying biological mechanism, control seizures, and reduce the occurrence of negative side effects.

Optimism for this approach of “precision medicine” for epilepsy grew following the complete sequencing of the human genome and fueled the hope that individual genetic information could be used to develop more specific ways to treat epilepsy. Precision medicine, also known as personalized medicine, is the “tailoring of medical treatment to the individual characteristics of each patient. It does not literally mean the creation of drugs or medical devices that are unique to a patient, but rather the ability to classify individuals into subpopulations that differ in their susceptibility to a particular disease or their response to a specific treatment.” Unfortunately, for most types of genetic epilepsy, the individual genetic makeup of a patient has not yet translated to clinical application of precision medicines for epilepsy. This has been due, in part, to the complexity of the underlying biological mechanisms as well as limitations in the technologies needed to advance genetic discovery to appropriate treatments.

However, the authors describe how epilepsy research is entering an exciting new phase that may enable new precision therapies for many more types of genetic epilepsy. Over the last decade, significant progress in advancing precision medicine approaches has been achieved for epilepsies caused by discrete mutation(s) in a single gene. This work has involved 1) acceleration and efficiency of gene sequencing technology and identification of epilepsy-causing, including the location and type of specific mutations in the DNA sequence of these genes, and 2) clarification of the neuronal function(s)/dysfunction of the corresponding protein and underlying biochemical pathways. In addition, the development of specific laboratory methods such as cell-based models that replicate aspects of the structure and function of the human brain and the use of zebrafish that are sensitive to ASMs have accelerated the testing of novel epilepsy treatments. Finally, new epilepsy gene-targeted technologies, for example, antisense oligonucleotides, are being tested in clinical trials, and there is active discussion about changes in clinical trial design that could enable smaller clinical trials needed for rare genetic epilepsies.

Despite these successes, multiple challenges remain for the future development and accessibility of precision therapies for epilepsy. First, genetic testing and counseling remain inaccessible to many groups, including the elderly and the poor, across the world. Second, nearly 70% of epilepsy cases involve more than one gene and thus require an improved understanding of disease risk in the context of multiple genetic mutations, overall genetic background, and environmental exposure. Third, although gene therapy is conceptually encouraging there are challenges related to large-scale development of safe, ethical, and equitable delivery of gene-based therapies to overcome. It will be critical for the research community to work together to overcome these challenges to ensure the delivery of new precision therapies for genetic epilepsies.

An important driver for the advancements that have been made toward the development of precision therapies are the many new stakeholders calling for action. Numerous patient advocacy groups, professional societies such as the American Epilepsy Society, government and non-profit funding agencies such as the National Institute of Neurological Disorders and Stroke and CURE Epilepsy, respectively, have collectively called for a coordinated and systematic approach to developing new epilepsy treatments. Progress stemming from this call to action could bring a new age of treatments for those with epilepsy, shifting from observational experience to data-driven and patient-centered precision therapy.

 

Literature Cited:

  1. Knowles JK, Helbig I, Metcalf CS, Lubbers LS, Isom LL, Demarest S, Goldberg EM, George AL, Lerche H, Weckhuysen S, Whittemore V, Berkovic SF, Lowenstein DH. Precision medicine for genetic epilepsy on the horizon: Recent advances, present challenges, and suggestions for continued progress. Epilepsia 2022
  2. Hesdorffer D, Logroscino G, Benn E, Katri N. Cascino G, Hauser W. Estimating risk for developing epilepsy. A population-based study in Rochester, Minnesota. Neurology 2011; 76:23–27
  3. Chen Z, Brodie MJ, Liew D, Kwan P. Treatment outcomes in patients with newly diagnosed epilepsy treated with established and new antiepileptic drugs. A 30-Year Longitudinal Cohort Study. JAMA Neurology 2018 75:279-286.

CURE Epilepsy Discovery: Identifying a Promising Novel Treatment for Infantile Spasms

Key Points:

  •  John Swann, PhD, and his team explored an underlying cause of infantile spasms (IS), a devastating epileptic encephalopathy (an epilepsy syndrome that can lead to deterioration of the brain) that typically begins within the first year of life. This new research, funded by the National Institutes of Health (NIH), was a direct result of Dr. Swann’s findings from his work as a member of the CURE Epilepsy Infantile Spasms Initiative, conducted from 2013-2017.
  • Standard treatments for IS work in only approximately 50% of patients and can have severe side effects. The need for additional effective therapies drove Dr. Swann and his team to explore a more effective treatment with fewer or, ideally, no side effects.
  • Through extensive experimentation with an established rat model of IS and parallel studies in human tissue removed during epilepsy surgery, Dr. Swann observed very low levels of an important growth factor in the brain which has the potential to be a promising new treatment for this severe form of epilepsy.


Deep Dive:

Infantile spasms (IS) is a rare catastrophic form of epilepsy with approximately 90% of the cases beginning within the first year of life [1,2]. The condition is characterized by seizures with sudden brief jerking movements of the arms and legs or head bobs and often, though not always, an atypical, chaotic pattern of brain waves on the electroencephalogram (EEG) known as hypsarrhythmia [3]. The seizures are accompanied by significant development delays as well as cognitive and physical deterioration [2]. Standard treatments include adrenocorticotropic hormone (ACTH) or prednisone, and the antiseizure medication vigabatrin [4]. Unfortunately, only approximately 50% of children with IS respond to these treatments and there remains no reliable way of predicting who will respond favorably [4]. Even if these treatments diminish IS symptoms for a specific patient, they can have serious side effects. Therefore, scientists have been searching for other drug targets with the ultimate goal of developing alternative therapies.

One of these scientists is Dr. John Swann, Professor of Pediatrics at the Baylor College of Medicine, Director of the Gordon and Mary Cain Pediatric Neurology Research Foundation, and Principal investigator at the Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, who leveraged findings from his work as part of the CURE Epilepsy Infantile Spasms Initiative (2013-2017). With additional funding from NIH, Dr. Swann and his team used a previously developed rat model of IS [5] that mirrors many of this disorder’s symptoms, to investigate spasms that result from pediatric brain injuries, such as those suffered during a traumatic birth.

He and the team wanted to determine if the level of a substance known as insulin-like growth factor-1 (IGF-1) was altered in the injured brains of both their rat model and in IS patients, the latter using brain tissue from IS patients who had undergone neurosurgery to stop their seizures. The rationale behind this experiment was based on two observations. The first is that the level of IGF-1 in the cerebrospinal fluid of IS patients with preexisting brain damage is low [6], and second is that IGF-1 activates a biological pathway crucial for proper brain development and neuronal function [7]. As hypothesized, data revealed that IGF-1 levels were lower in brain tissue from both the rat model and from infants with IS. Data also showed that reduced expression of IGF-1 in the rat model affected the biological pathways critical for neurodevelopmental processes [8].

These promising findings suggested that increasing the amount of IGF-1 in the brains of the rat model might alleviate at least some of the symptoms of IS. To test this idea, the researchers employed a shorter version of IGF-1 called (1-3)IGF-1 which is a natural breakdown product of IGF-1 that can cross the blood-brain barrier with much higher efficiency than the full-length IGF-1 [9].

After confirming that (1-3)IGF-1 could activate the same biological pathways responsible for regulating the processes involved in early brain development as full-length IGF-1, the researchers administered it to their rat model and successfully eliminated both the spasms as well as the hypsarrhythmia in most rodents. This exciting finding suggests that this smaller (1-3)IGF-1 or perhaps an IGF-1-like drug may one day be used to treat IS patients immediately after the condition is diagnosed. This new approach could potentially reduce or even eliminate the associated neurodevelopmental and cognitive effects of this devastating disorder without the side effects of the currently available treatments. Dr. Swann states that this research and subsequent additional funding from NIH to continue the work would not have been possible without his participation in the CURE Epilepsy Infantile Spasms Initiative.

 

Literature Cited:

  1. Pellock, JM et al. Infantile spasms: a US consensus report. Epilepsia 2010; 51: 2175-2189
  2. Cowan, L.D. & Hudson, L.S. The epidemiology and natural history of infantile spasms. Child Neurol. 1991; 6(4): 355-364.
  3. Gibbs, E.L., Fleming, N.M, & Gibbs, F.A. Diagnosis and prognosis of hypsarrhythmia and infantile spasms. Pediatrics 1954; 13(1): 66-73.
  4. Knupp, K.G. et al. Response to treatment in a prospective national infantile spasms cohort. Neurol. 2016; 79(3): 475-484.
  5. Lee, C.L. et al. A new animal model of infantile spasms with unprovoked persistent seizures. Epilepsia 2008; 49(2): 298-307.
  6. Riikonen, R.S. et al. Insulin-like growth factor-1 is associated with cognitive outcome in infantile spasms. Epilepsia 2010; 51(7): 1283-1289.
  7. O’Kusky, J. & Ye, P. Neurodevelopmental effects of insulin-like growth factor signaling. Neuroendrocrincrinol. 2012; 33(3): 230-251.
  8. Ballester-Rosado, C.J. et al. A role for insulin-like growth factor 1 in the generation of epileptic spasms in a murine model. Neurol. 2022; 92(1): 45-60.
  9. Yamamoto, H. & Murphy, L.J. Enzymatic conversion of IGF-1 to des(1-3)IGF-1 in rat serum and tissues: a further potential site of growth hormone regulation of IGF-1 action. Endocrinol. 1995; 146(1): 141-148.

CURE Epilepsy Discovery: Investigating Mechanism of the Progression of Epilepsy

Key Points:

  • The development of seizures is associated with many changes in the brain; one of these changes is alterations in the white matter (the deep part of the brain) composed of axons covered in myelin. Myelin is a substance that acts as a nerve insulator and is critical for communication between neurons.
  • Dr. Juliet Knowles at Stanford University was granted both a CURE Epilepsy Taking Flight and a CURE Epilepsy Research Continuity Fund award to investigate whether changes in myelin might play a role in the development of epilepsy. Through her research, the team discovered that abnormal neuronal activity during absence seizures may lead to changes in myelination. The changes in myelin, in turn, lead to seizure progression.
  • This research paves the way for future studies that may identify ways to prevent harmful changes in myelination to treat some forms of epilepsy.


Deep Dive:

Some types of epilepsy are progressive, and the disease progression may manifest in the form of more frequent seizures, worsened control of seizures, or decline of cognition.[1] Progression of seizures has a direct correlation to the severity of epilepsy as time progresses.[2] Multiple factors may contribute to how seizures progress, but one factor that had not been investigated is a change, (known as plasticity), in the white matter or myelin of the brain. Myelin is a substance that acts as a form of insulation around the nerve cells of the brain and is essential for the conduction of electrical impulses between neurons and for the proper functioning of the brain. In fact, this white coating of myelin is what gives the collection of axons deep inside the brain the name “white matter”. Plasticity or changes in myelination can occur in response to neuronal activity and are important in the non-epileptic brain for functions such as learning, memory, and attention.[3,4] The team found that seizures in newborn infants with genetic forms of epilepsy may be associated with abnormalities in myelination.[5] These findings suggested that myelin plasticity might also occur in response to seizures. 

With her CURE Epilepsy Taking Flight Award, generously funded by the Ravichandran Foundation, Dr. Knowles and her colleagues sought to determine whether changes in myelination caused by a type of seizure called an absence seizure (formerly known as a petit mal seizure) contribute to the progression of epilepsy.[6] And when COVID-19 forced this study to be put on a temporary hold, the CURE Epilepsy Research Continuity Fund award, generously funded by the Cotton Family in memory of Vivian Cotton, helped Dr. Knowles’ team to finish these experiments when laboratories reopened. For her study, Dr. Knowles hypothesized that changes in myelin might influence seizure severity in absence seizure spreading.

Absence seizures are characterized by the abrupt stopping of behavior (“behavioral arrest”) and a specific pattern of brain activity. Even though absence seizures are typically brief, an individual can have an extremely high number of seizures in a day.[7, 8] Absence seizures originate in connections between two parts of the brain called the thalamus and cortex, after which seizure activity is transmitted through a large brain network by myelin-coated axons in white matter.[9, 10] 

The team used rodent models which had specific genetic mutations in their neurons that produce absence seizures. The pattern of seizure progression in these animals is similar to what is found in children with progressive forms of epilepsy.[2, 8] Electroencephalogram (EEG) was used to study electrical activity in the brain and the structure of neurons was examined using sophisticated microscopy techniques.[6] Additional techniques used to investigate the role of seizures in myelination included genetic interventions to block myelination (the process by which layers of myelin are produced) and drugs that decreased seizures.[6]

By using these methods, Dr. Knowles’ team first observed that there was an increase in myelination within the seizure network in seizure-prone animals, but this was seen only once seizures had started. This suggests that there is something unique and specific about the seizure activity that impacts myelination. Additionally, when Dr. Knowles’ team blocked seizures either genetically or using drugs, the increase in myelination was prevented. When the team blocked this abnormal myelination, the number of seizures decreased, and neuronal hypersynchrony decreased as well.[6] Neuronal hypersynchrony is the process by which networks of neurons fire together in an extremely organized and coordinated but abnormal way and is thought to underlie some aspects of seizure onset and spreading.[11]

The current study by Dr. Knowles’ group is the first that clearly shows that abnormal neuronal activity (in this case, due to absence seizures) can lead to harmful changes in myelination, which contribute to the continued progression of epilepsy.[6] Future work in the field will look at the exact molecules and neurotransmitters involved to better characterize this change in myelination. Although more studies are necessary, the current work suggests that developing treatments that address both abnormal neuronal activity and the associated abnormal myelination could more effectively prevent seizures and cognitive difficulties.[12] 

 

Literature Cited:

  1. Coan AC, Cendes F. Epilepsy as progressive disorders: what is the evidence that can guide our clinical decisions and how can neuroimaging help? Epilepsy Behav. 2013 Mar;26:313-321.
  2. Brigo F, Trinka E, Lattanzi S, Bragazzi NL, Nardone R, Martini M. A brief history of typical absence seizures – Petit mal revisited Epilepsy Behav. 2018 Mar;80:346-353.
  3. McKenzie IA, Ohayon D, Li H, de Faria JP, Emery B, Tohyama K, et al. Motor skill learning requires active central myelination Science. 2014 Oct 17;346:318-322.
  4. Pan S, Mayoral SR, Choi HS, Chan JR, Kheirbek MA. Preservation of a remote fear memory requires new myelin formation Nature Neuroscience. 2020 2020/04/01;23:487-499.
  5. Sandoval Karamian AG, Wusthoff CJ, Boothroyd D, Yeom KW, Knowles JK. Neonatal genetic epilepsies display convergent white matter microstructural abnormalities Epilepsia. 2020 Dec;61:e192-e197.
  6. Knowles JK, Xu H, Soane C, Batra A, Saucedo T, Frost E, et al. Maladaptive myelination promotes generalized epilepsy progression Nature Neuroscience. 2022 2022/05/01;25:596-606.
  7. Albuja A.C. KGQ. Absence Seizure. [Updated 2021 Dec 13]. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing 2022.
  8. Guerrini R, Marini C, Barba C. Generalized epilepsies Handb Clin Neurol. 2019;161:3-15.
  9. Musgrave J, Gloor P. The role of the corpus callosum in bilateral interhemispheric synchrony of spike and wave discharge in feline generalized penicillin epilepsy Epilepsia. 1980 Aug;21:369-378.
  10. Fogerson PM, Huguenard JR. Tapping the Brakes: Cellular and Synaptic Mechanisms that Regulate Thalamic Oscillations Neuron. 2016 Nov 23;92:687-704.
  11. Jiruska P, de Curtis M, Jefferys JGR, Schevon CA, Schiff SJ, Schindler K. Synchronization and desynchronization in epilepsy: controversies and hypotheses J Physiol. 2013;591:787-797.
  12. Li MCH, Cook MJ. Deep brain stimulation for drug-resistant epilepsy Epilepsia. 2018 Feb;59:273-290.

CURE Epilepsy Discovery: Identifying Human Brain Regions that Regulate Breathing as Eventual Targets for Direct SUDEP Intervention

Key Points:

  • CURE Epilepsy Award grantee Dr. Nuria Lacuey and her team sought to identify specific parts of the brain essential for regulating breathing, a fundamental function whose failure following a seizure is primarily responsible for Sudden Unexpected Death in Epilepsy (SUDEP).
  • The team recruited patients who were being evaluated for epilepsy surgery and who formally agreed to enroll in a study that had them perform various breathing exercises while having different areas of their brain electrically stimulated with varying intensities.
  • Quantitative analyses of the data revealed that four specific areas of the cortex of the brain affected the patients’ breathing responses, depending on the strength and frequency of the electrical stimulation. Two of these areas resulted in enhanced respiratory activity.
  • Additional data from more patients is needed, but Dr. Lacuey hopes to use these valuable results to develop a device that will stimulate critical areas of the brain following seizures to enhance breathing and avoid its cessation, thereby preventing SUDEP.


Deep Dive:

SUDEP is the most frequent cause of death among people with drug-resistant epilepsy [1,2]. Although different biological processes may contribute to SUDEP, the most prominent appears to be a phenomenon known as central apnea, a condition in which breathing repeatedly stops and starts, usually while sleeping, during or immediately after a severe seizure [3,4]. There is compelling evidence that breathing irregularities are an underlying cause of SUDEP. Research to date has almost exclusively concentrated on the role of an area of the brain called the brainstem [5], which ultimately connects higher cortical regions of the brain to the spinal cord. Although the brainstem plays a crucial role in maintaining respiratory activity, it may not be the only contributing area. Indeed, areas of the cortex have also been implicated [6], but the specific roles different areas of the cortex play in modulating breathing is unclear. Most importantly, there are currently no strategies for directly improving respiratory function during the dangerous period between seizure-induced central apnea and death.

One possible approach would be to electrically stimulate specific areas of the brain to maintain respiratory function during this critical period. As a first step, it is vital to assess the role of specific areas of the brain and what intensity and frequency of the electrical current might have beneficial or detrimental effects on breathing. Developing such an innovative method requires a detailed understanding of the relationship between brain electrical activity and breathing responses, specifically how brain regions are structurally and functionally linked through their neuronal connections, collectively known as the connectome [7,8].

Research on this approach was conducted by Dr. Lacuey and her team in the Department of Neurology at the University of Texas Health Science Center  in Houston, TX. Nineteen patients who suffered from drug-resistant epilepsy and who were being evaluated for epilepsy surgery consented to be enrolled in the study [9]. Pinpointing the exact seizure focus without damaging surrounding healthy tissue necessitated placing electrodes directly on the brains of these patients and then, electrically stimulating various brain regions for clinical mapping.

Electrodes were implanted in seven brain regions common to all 19 participants, and thus, these were the regions selected for comprehensive investigation. The goal was to ascertain whether electrical stimulation of each of these seven regions would affect breathing responses and, if so, whether the resulting respiratory activity would be enhanced or inhibited. Equally important was to determine the stimulation intensity as well as frequency necessary to elicit such responses. Electrical stimulation was carried out at a current of 1-10 milliamps (mA) and a frequency of 50 Hertz for 0.2 milliseconds [9].

Quantitative analyses of the data showed that electrical stimulation affected breathing responses in four of the seven different brain regions tested. Stimulation of two of these regions, specifically within the frontal portions of areas called the temporal lobe and cingulate gyrus, promoted breathing enhancement at a relatively low current (less than 3 mA) but not at the higher electrical current conditions tested [9]. Future experiments will require a larger group of patients, finer mapping of the identified brain regions, and exploration of brain regions other than the seven examined in the current study. Subsequent experiments will also include an evaluation of electric current and frequency as well as how any observed changes in respiratory control interact with the breathing mechanisms of the brainstem.

The fact that electrical stimulation of four cortical regions affected respiration, and that two of these areas enhanced breathing is an exciting finding. Significantly, this CURE Epilepsy funded research supports the idea that an implantable device capable of electrically stimulating pre-identified cortical regions of the brain to enhance breathing at critical times to prevent SUDEP may eventually be possible.

 

Literature Cited:

  1. Jones, L.A. & Thomas, R.H. Sudden unexpected death in epilepsy: insights from the last 25 years. Seizure 2017; 44: 232-236.
  2.   Devinsky, O. et al. Sudden unexpected death in epilepsy: epidemiology, mechanisms, and prevention. Lancet Neurol. 2016; 15(10): 1075-1088.
  3.   Vilella, L. et al. Postconvulsive central apnea as a biomarker for sudden unexpected death in epilepsy (SUDEP). Neurology 2019; 92(3): e171-e182.
  4.   So, E.L., Sam, M.C., & Lagerlund, T.L. Postictal central apnea as a cause of SUDEP: evidence from near-SUDEP incident. Epilepsia 2000; 41(11): 1494-1497.
  5.   Patodia, S. et al. The ventrolateral medulla and medulla raphe in sudden unexpected death in epilepsy. Brain 2018; 141(6): 1719-1733.
  6.   Herrero, J.L. Breathing above the brain stem: volitional control and attentional modulation in humans. J. Neurophysiol. 2018; 119(1): 145-159.
  7.   Bethlehem, R.A.J. et al. Brain charts for the human lifespan. Nature 2022; 604(7906): 525-533.
  8.   Fan, Q. et al. Mapping the human connectome using diffusion MRI at 300 mT/m gradient strength: Methodological advances and scientific impact. Neuroimage 2022; 254:118958.
  9.   Ganne, C. et al. Limbic and paralimbic respiratory modulation: from inhibition to enhancement. Epilepsia 2022; Epub