The Ictal EEG of Seizures Induced by Unilateral Electroconvulsive Therapy: A Model of Provoked Neocortical Seizures in Man?
Abstract number :
1.188
Submission category :
Year :
2000
Submission ID :
3171
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Keith J Nagle, Daniel Haupt, John Helzer, U of Vermont, Burlington, VT; Washington U, St. Louis, MO.
RATIONALE: Seizures induced by unilateral electroconvulsive therapy (ECT) with electrodes placed in the d'Elia position have not been previously characterized by EEG recordings using greater than 6 channels. To test the hypothesis that these seizures may represent neocortical seizures with rapid secondary generalization the following pilot study was undertaken. METHODS: After obtaining IRB approval, patients who were to undergo unilateral ECT for the treatment of unipolar depression were screened for an absence of other neuropsychiatric illness or epilepsy risk factors. Informed consent was obtained. Right unilateral ECT was administered using a standard protocol with 5 cm steel stimulating electrodes placed in the d'Elia position, a constant current stimulator delivering an 800 mA biphasic pulse at 90 Hz and pulse width of 1 msec. The stimulus duration was 0.5-4.0 sec. The first stimulus was delivered at threshold (T) and treatment on subsequent days at 2.5T. Anesthesia was obtained using glycopyrolate, d-tubocurarine and methohexital. Digital EEG was recorded using electrodes placed using the International 10-20 system except that AT1+2 were substituted for F7+8. Ictal EEG was visually analyzed using longitudinal and transverse bipolar montages. RESULTS: Twelve seizures were recorded in 7 patients, ages 28-78 years. The seizure duration ranged from 23-78 seconds. All seizures contained higher amplitude and increased signal complexity over the right parasagittal and vertex scalp regions (Cz,C4,F4,Fz). Eight of 12 seizures had postictal lateralized features of more prominent slow activity and attenuation over the right hemisphere. The other 4 had non-lateralized postictal EEG changes. CONCLUSIONS: Visual analysis of the ictal EEG of seizures induced by unilateral ECT using the d'Elia position reveal changes that are consistent with neocortical seizures arising from the right frontocentral region with rapid secondary generalization. This method may represent a useful model of provoked neocortical seizures in man.