Delayed Responses to Single Pulse Electrical Stimulation Can Identify Epileptogenic Cortex in the Human Brain
Abstract number :
B.01
Submission category :
Year :
2001
Submission ID :
2966
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
G. Alarcon, MD, Clinical Neurophysiology, King[ssquote]s College Hospital, London, United Kingdom; A. Valentin, MD, Clinical Neurophysiology, King[ssquote]s College Hospital, London, United Kingdom; M.D. Anderson, MSc, Clinical Neurophysiology, King[ssquo
RATIONALE: The aim of the present study was to establish whether intracranial cortical EEG responses to single pulse electrical stimulation in vivo could be used in humans to identifiy epileptogenic cortex.
METHODS: We have studied 36 patients with refractory epilepsy in whom subdural or intracerebral electrodes were implanted for assessment of epilepsy surgery. We compared cortical responses to single pulse stimulation (up to 8 mA, 1 ms duration) in areas where seizure onset occurred with responses recorded elsewhere.
RESULTS: Two types of responses were seen: a) Early responses: spikes, sharp waves and/or slow waves starting within 100 ms after stimulus, were observed in all patients when most of the regions were stimulated and showed no obvious difference between epileptogenic and non-epileptogenic cortex; b) Delayed responses: spikes or sharp waves starting between 100 ms and 1 sec after stimulation, were seen in 20 patients with a distribution that was significantly associated with the regions where seizure onset was observed.
CONCLUSIONS: We conclude that the presence of delayed responses can identify epileptogenic cortex, particularly in temporal lobe epilepsy. This technique could be used to guide implantation of intracranial electrodes in order to maximise the likelihood of identifying a focal seizure onset at a later stage during video-telemetry. Also, it could be useful to support ictal data during the period of video[ndash]EEG monitoring, particularly in patients who have few seizures.
Support: The Fund for Epilepsy
Guy[ssquote]s, King[ssquote]s and St Thomas[ssquote] School of Medicine