Update on Epilepsy: New Devices and Treatment

Epilepsy Seizures Can Persist with Medications Alone. Epilepsy is the fourth most common neurological disorder. 1 in 26 people will develop epilepsy at some point in their lifetime. As many as one-third of those with epilepsy experience seizures that persist in spite of treatment with medications alone. Vagus Nerve Stimulation (VNS). VNS is designed to prevent seizures by sending regular, mild pulses of electrical energy to the brain via the vagus nerve. The VNS Therapy System is an FDA-approved medical device specifically developed for the adjunctive treatment of drug-resistant epilepsy. Studies show that a majority of people with drug-resistant epilepsy experience a 50 to 90% reduction in seizures with the VNS Therapy System.

New Device Detects Heart Rate Increases During Seizures. The FDA just approved the AspireSR® generator for the VNS Therapy System to provide responsive stimulation to heart-rate increases often associated with seizures in people with epilepsy. Studies show 82% of patients with epilepsy experience rapid heart-rate increase associated with a seizure. The AspireSR generator uses a proprietary, patent protected, customizable cardiac-based algorithm to detect relative heart rate increases and deliver automatic stimulation.Reference: PR Newswire. Cyberonics announces FDA approval of the AspireSR® Generator for VNS Therapy® http://www.prnewswire.com/news-releases/cyberonics-announces-fda-approval-of-the-aspiresr-generator-for-vns-therapy-300092511.html. 2 June 2015.

Electrodermal Activity in the Brain. Changes in electrodermal activity occur as a result of activation of regions deep in the brain. Amygdala or hippocampus activation elicits skin conductance on the same side of the body. Stimulating 4 brain regions on the left and 4 on the right with depth electrodes produces large skin conductance on the same side.Biomarker for Sudden Unexpected Death in Epilepsy. Studies show that electrodermal activity plus motion is better than motion alone for automated grand mal seizure detection. Larger electrodermal activity correlates with longer post-ictal generalized EEG suppression. Post-ictal generalized EEG suppression is as an important biomarker for sudden unexpected death in epilepsy. Electrodermal activity can be used both as an indirect biomarker for sudden unexpected death in epilepsy and a measure of autonomic disruption.

New Wristband Device Measures Electrodermal ActivityAmbulatory electrodermal activity sensors using dry electrodes and placements on the wrist or ankle have been validated in epilepsy studies.Studies show significant electrodermal activity occurred in 86% of patients with complex partial seizures, which may help automate their detection.A new wristband device (Embrace) measures autonomic data from the skin that reflects activation of deep brain circuits, while being comfortably and easily measured 24/7.Personalized autonomic patterns can be examined over time to objectively examine interactions with automated external defibrillators.Reference: Empatica. Advanced research on human behavior https://www.empatica.com/science#literature-picard-a.

Surgery for Focal Epilepsy.Intractable focal epilepsy has profound effects on cognition and quality of life.Epilepsy surgery can free focal epilepsy patients from seizures, however, surgery can fail due to an incomplete delineation of the epileptogenic zone.Functional magnetic resonance imaging or electrocorticography produce inconsistent results in evaluating brain networks in epilepsy.Magnetoencephalography for Non-invasive Whole-brain Recordings.Magnetoencephalography allows non-invasive whole-brain recordings, and can be used to study both long-range network disturbances in focal epilepsy and regional connectivity at the epileptogenic zone.

Global Brain Connectivity and Epilepsy. Researchers used magnetoencephalography recordings from presurgical epilepsy patients to examine global functional connectivity maps in patients versus controls.Regional functional connectivity maps at the region of resection were compared to the homotopic non-epileptogenic region in the contralateral hemisphere.A study compared 61 epilepsy patients who had brain surgery for epilepsy that was refractory to medical therapy with 31 controls.

Brain Connectivity Predicts Freedom from Seizure Activity.Results show the epilepsy patients had decreased resting-state functional connectivity in widespread regions.Those with longer epilepsy duration and higher frequency of consciousness-impairing seizures had decreased mean global connectivity.Patients with increased regional connectivity within the resection site were more likely to achieve postoperative seizure freedom (87.5%) than those with neutral (64.3%) or decreased (47.8%) regional connectivity.The researchers conclude that widespread global decreases in functional connectivity in patients with focal epilepsy may reflect deleterious long-term effects of recurrent seizures.Enhanced regional functional connectivity at the area of resection may help predict seizure outcome and aid surgical planning.Reference: Englot DJ, et al. Global and regional functional connectivity maps of neural oscillations in focal epilepsy Brain. published online 16 May 2015.http://brain.oxfordjournals.org/content/early/2015/05/15/brain.awv130

Take-home Points. The AspireSR generator offers a minimally invasive option to allow clinicians to detect and respond to seizure events in real time.New wristband device measures electrodermal activity as a marker for seizure activity.Brain connectivity patterns may help locate which part of the brain is causing epileptic seizures, and may help plan more effective surgeries.