Surgical outcomes with non-invasive presurgical evaluation in MRI determined bilateral mesial temporal sclerosis: A retrospective cohort study.

Background & Objective: Epilepsy surgery for bilateral hippocampal sclerosis continues to pose a challenge and outcomes even with invasive evaluations have not been very promising. Very few studies have analyzed surgery outcomes for patients with MRI determined, bilateral mesial temporal sclerosis (MTS) after non-invasive pre-surgical evaluation.
Material and Methods: We studied 35 patients with bilateral MTS who underwent anterior temporal lobectomy (ATL) after non-invasive pre-surgical evaluation. Clinical history, EEG, neuropsychology profile and symmetry of MTS on MRI were reviewed in the groups of 'seizure free' and 'not seizure free' patients.
Results: At an average follow up of 44 months (range 12-110 months), 26 out of 35 patients (74%) were seizure free. Unilateral interictal discharges were seen in 57% patients. 94% patients had unilateral ictal EEG onset. Bilateral interictal discharges were significantly associated with 'not seizure free' outcome (p = 0.02). Pre-operatively, 24 (71%) patients had bilateral (verbal and visual) memory impairment while 10 (28%) patients had unilateral (verbal or visual) memory impairment and 1 patient had a normal memory profile. Overall, no significant decline in memory was seen in left or right surgery groups post-operatively. There was significant improvement in Quality of Life scores in all patients (p = <0.0005).
Conclusion: Patients with bilateral MTS on MRI can be unilateral on electro physiology and neuropsychology, and can have a very good surgical outcome. In a setting of limited resources, a noninvasive pre-surgical protocol can be used. With proper patient selection, the outcomes may be comparable to those reported with invasive pre-surgical protocols. Patients with unilateral interictal and ictal EEG have the best outcome. Up to 50% patients with bilateral interictal discharges can have a seizure free outcome. Patients with bilateral independent seizure onset have a less favourable prognosis. Patients who are not seizure free can still attain worthwhile improvement in seizure frequency without significant decline in memory and some improvement in quality of life.
(Copyright © 2015 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.)