Extent of Ictal Origin in Mesial Temporal Lobe Epilepsy Patients Monitored with Subdural Electrodes Predicts Surgical Outcome.
Abstract number :
2.305
Submission category :
Year :
2001
Submission ID :
153
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
A. Prasad, MD, Neurology, University of Virginia Medical Center, Charlottesville, VA; S.V. Pacia, MD, Neurology, New York University Medical Center, New York, NY; O. Devinsky, MD, Neurology, New York University Medical Center, New York, NY; W.K. Doyle, MD
RATIONALE: To explore the differences in the surgical outcome of mesial temporal lobe epilepsy (MTLE) patients with ictal origin in the anterior/midtemporal and anterior/midtemporal plus posterior temporal subdural strips. In one study, approximately 20% of patients with MTLE had an abnormal electrical focus identified by depth electrodes in posterior hippocampus and had suboptimal surgical outcome. Some centers use subdural strip electrodes as a substitute of depth electrodes that sample the uppermost part of the mesial parahippocampal gyrus rather than the hippocampus. It is unclear whether ictal origin based on subdural strip recording, too, has similar prognostic implications.
METHODS: We reviewed surgical outcome of 34 consecutive MTLE patients monitored with subdural grid and strips. All had radiologic and histologic proof of mesial temporal sclerosis (MTS). WADA and neuropsychologic tests were performed in all, and PET/SPECT in 18 patients. All patients had an ipsilateral supra- and infra-sylvian grid, and anterior, middle, and posterior subtemporal strips. Based on ictal onset in the mesial part of the 3 subtemporal subdural strips, seizure origin was classified into anterior/middle subtemporal (n=30), or anterior/middle and posterior subtemporal (n=6) regions. A radical amygdalo-hippocampectomy and tailored anterior temporal lobectomy was performed in all cases. Follow-up period ranged between 3.5-7 years.
RESULTS: Overall 28/36(80%) patients had successful (class -I/II) Engel[ssquote]s surgical outcome. Successful outcome in patients with seizure origin in anterior/middle subtemporal region was 90%(26/30) compared with patients with seizure origin in anterior/middle and posterior subtemporal regions 33%(2/6)(p value=0.014).
CONCLUSIONS: In patients with MTLE monitored by subdural strips,1) seizure origin in anterior/midtemporal region predicts a significantly better outcome compared with seizure origin in anterior/midtemporal plus posterior temporal regions,and 2) overall surgical outcome is comparable to prior studies using depth electrodes.