June 2, 2020

Post-Ictal Accelerometer Silence as a Marker of Post-Ictal Immobility

Abstract, published in Epilepsia

Objective: Movement-based wearable sensors are used for detection of convulsive seizures. The identification of the absence of motion following a seizure, known as post-ictal immobility (PI), may represent a potential additional application of wearables. PI has been associated with potentially life-threatening complications and with sudden unexpected death in epilepsy (SUDEP). This study aimed to assess whether wearable accelerometers (ACCs) could be used as a digital marker of PI.

Method: Devices with embedded ACCs were worn by patients admitted to an epilepsy monitoring unit. Participants with convulsive seizures were included in the study. PI presence and duration were assessed by experts reviewing video recordings. An algorithm for the automatic detection of post-ictal ACC silence and its duration was also developed and the relationship between the automatically detected duration of post-ictal ACC silence and the duration of the expert-labeled PI was analyzed.

Results: Twenty-two convulsive seizures were recorded from 18 study participants. Twenty were followed by PI and two by agitation. The automated estimation of post-ictal ACC silence identified all the 20 expert-labeled PI. Analysis showed that the duration of the post-ictal ACC silence was correlated with the duration of PI, the age of study participants and the duration of post-ictal generalized electroencephalography suppression (PGES), defined as the immediate post-ictal, generalized absence of EEG activity.

Significance: Researchers highlight a novel application of wearables as a way of recording post-ictal manifestations associated with an increased risk of SUDEP. The occurrence of a fatal seizure is unpredictable and the continuous, non-invasive, long-term identification of risk factors associated with each individual seizure may assume great clinical importance.

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