January 11, 2018

Transcranial magnetic stimulation not a good biomarker for epilepsy, study finds

This study published in the February 2018 issue of Brain examined long-interval intracortical inhibition, which is a measure that helps researchers study the balance of excitation/inhibition in the brain.

From the abstract: Cortical excitability, as measured by transcranial magnetic stimulation combined with electromyography, is a potential biomarker for the diagnosis and follow-up of epilepsy. We report on long-interval intracortical inhibition data measured in four different centres in healthy controls (n = 95), subjects with refractory genetic generalized epilepsy (n = 40) and with refractory focal epilepsy (n = 69). Long-interval intracortical inhibition was measured by applying two supra-threshold stimuli with an interstimulus interval of 50, 100, 150, 200 and 250 ms and calculating the ratio between the response to the second (test stimulus) and to the first (conditioning stimulus). We compared the long-interval intracortical inhibition response ratios between the different subject types.

Based on our results, we suggest that long-interval intracortical inhibition as measured by transcranial magnetic stimulation and electromyography is unlikely to have clinical use as a biomarker of epilepsy.