Correlation of Electrophysiological Findings from Combined Cortical Grid and Intracerebral Depth Electrode Recordings to Magnetic Resonance Imaging Findings and Clinical Outcomes in Temporal Lobectomy Patients
Abstract number :
2.295
Submission category :
Year :
2001
Submission ID :
2128
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
A. Krumholz, MD, Neurology, University of Maryland Medical School, Baltimore, MD; J.L. Hopp, MD, Neurology, University of Maryland Medical School, Baltimore, MD; H.M. Eisenberg, MD, Neurosurgery, University of Maryland Medical School, Baltimore, MD; D.M.
RATIONALE: Simultaneous implantation of subdural grid and intracerebral depth electrodes is a surgical technique that offers precise electrophysiological data on site of seizure origin in candidates for temporal lobectomy. However the clinical relevance of such electrophysiological findings is not well defined.
METHODS: We reviewed all temporal lobectomy patients who had simultaneous intracerebral grid and depth electrodes at the University of Maryland Medical Center. All patients required temporal subdural grids for further localization or language mapping. We reviewed all such patients and correlated sites of seizure onset with their MRI findings and clinical outcomes.
RESULTS: We analyzed 39 temporal lobectomy patients with simultaneous subdural grid and depth electrodes. No major operative or post-operative complications were related to the procedure. Intracerebral subdural grid and depth electrodes revealed mesial temporal seizure onsets in 29 patients (74%), while 10 (26%) had lateral (neocortical)onsets. On MRI, 20 patients (51%) showed mesial temporal sclerosis (MTS) or other mesial temporal lobe lesions, and 19 patients (49%) had normal mesial temporal structures. Presence of MTS or mesial temporal lesions on MRI was predictive of mesial temporal seizure onset in 18 of 20 patients (90%). Among patients with normal mesial temporal structures on MRI, only 11 of 19 (58%) had mesial temporal onsets, and 8 (42%) had lateral onsets. In patients with MTS or lesions on MRI, 80% were seizure-free, but only 47% with normal mesial temporal structures on MRI were seizure-free. In addition, of 29 patients with mesial temporal seizure onsets, 24 (83%) became seizure-free, but of the 10 with lateral onsets, only 3 (30%) were seizures-free. The 17 patients with both MTS or lesions and mesial onsets had the best outcomes, with 16 (94%) seizure-free.
CONCLUSIONS: Lateral seizure onsets were found in 26% of temporal lobectomy patients and were predictive of poorer outcomes than mesial temporal onsets. Mesial temporal sclerosis or lesions were predictive of mesial temporal onsets and good outcome. In contrast, normal mesial structures on MRI were associated with lateral temporal onsets and poorer outcomes. Patients with both MTS and mesial temporal onsets had the best outcomes with 94% becoming seizure-free. The technique of combining subdural grids and intracerebral depth electrodes compliments MRI findings and aids in predicting outcome for patients undergoing temporal lobectomy for intractable epilepsy.