EPILEPTOGENIC FAST OSCILLATIONS IN PATIENTS WITH HEMIMEGALENCEPHALY BEFORE AND AFTER FUNCTIONAL HEMISPHERECTOMY
Abstract number :
1.060
Submission category :
3. Clinical Neurophysiology
Year :
2008
Submission ID :
9182
Source :
www.aesnet.org
Presentation date :
12/5/2008 12:00:00 AM
Published date :
Dec 4, 2008, 06:00 AM
Authors :
Madoka Yamazaki, Zulma Tovar-Spinoza, Derrick Chan, Cristina Go, Katsumi Imai, Ayako Ochi, B. Chu, Tomoyuki Akiyama, J. Rutka, J. Drake, O. Snead and H. Otsubo
Rationale: Hemimegalencephaly is well known cause of epileptic encephalopathy in neonates in most cases. We reported fast oscillations (FOs) in neonates and infants with hemimegalencephaly before the surgery at the last AES meeting. In this study, we analyzed FOs and EEG patterns after surgery comparing those of the preoperative. Methods: We collected five patients with total hemimegalencephaly (4) and partial hemimegalencephaly (1). We retrospectively analyzed 13 EEGs (sampling rate 200Hz or 500Hz) between 3 days and 2 years of age before surgery and 10 EEGs after surgery. We applied multiple band frequency analysis (MBFA) to analyze maximum frequency and power of FO (~60Hz for 200Hz sampling; ~150Hz for 500Hz sampling) in selected interictal periods. Results: Maximum interictal FOs ranged between 22 and 56 Hz (mean 37Hz) in 13 EEGs with 5 patients before surgery. EEG patterns over hemimegalencephaly side consisted of suppression-burst (5 EEGs), triphasic complex (4), continuous high amplitude slow waves with spikes (3), and frequent high amplitude spike and slow waves (1). All 5 patients had functional hemispherectomy. The age of surgery ranged from 11 weeks to 35 month old. Postoperatively all 5 patients became seizure free. After surgery, maximum interictal FO ranged between 23 and 57 Hz (mean 37 Hz) in 10 EEGs. EEG pattern over hemimegalencephaly side changed to frequent spike/sharp and slow waves (7 EEGs), high amplitude slow waves superimposed by spikes (2) and continuous spike and slow waves (1). Conclusions: We confirmed interictal epileptogenic FOs in patients with hemimegalencephaly before and after surgery. The frequency of interictal FOs did not change postoperatively compared with those on the preoperative EEG even when they became seizure free. The EEG expressions altered during maturation and course. The epileptogenic FOs established from the beginning in hemimegalencephaly patients remained in similar frequency range in the residual brains even after the disconnection not to produce clinical seizures.
Neurophysiology