Is Epilepsy Surgery on both Hemispheres Effective?
Background: Patients with bilateral independent seizure foci are poor candidates for conventional resective epilepsy surgery. The authors have therefore used minimally invasive procedures to treat such patients. In this paper, the result of a large series of patients treated by this approach is examined to determine the effectiveness of this approach. Materials and Methods: The series had 61 patients. The range of follow-up was 15–90 months. The mean follow-up was 41.5 months with a median of 37 months. Patients’ ages at the time of surgery ranged from 3 to 54 years, with a mean of 11.3 and median of 6. Male to female ratio was 39/22. Fifty patients had complex partial seizures, 3 had Lennox-Gastaut syndrome, 4 had myotonic seizures, 2 had infantile spasm, and 2 had myoclonic seizures. Preoperative evaluation included: video electroencephalogram (EEG) monitoring using scalp electrodes, neuropsychological evaluation, magnetic resonance scans, positron emission topography and/or single photon emission computed tomography scans, magnetoencephalogram, Wada test and video EEG recording using subdural electrodes. Multiple subpial transection (MST) was the principle procedure. This procedure was supplemented (17 patients) with minimal cortical resection when intraoperative electroencephalogram indicated that an area failed to respond to MST. When an additional epileptogenic focus was present in the amygdala-hippocampus complex (5 patients), it was treated with stereotactic amygdala-hippocampotomy. The eloquent cortex was treated in 51 patients. The number of lobes treated was 2 in 5 patients, 3 in 5 patients, 4 in 10 patients, 5 in 2 patients, 6 in 38 patients and 8 in 1. Results: Seizure outcome based on Engel’s modified classification was as follows: 32 patients (52.45%) were class I, 5 (8.2%) were class II, 15 (24.59%) were class III, 3 (4.9%) were class IV and 6 (9.83%) were class V. There was no statistical difference between those who were operated on of the first half of the series and those who were operated on of the second half of the series (p = 0.1636). Similarly, there was no statistical difference between this series and two large series in which MST had been performed on one hemisphere (p values of 0.6863 and 0.7337). There was no statistical difference between those who had MST alone and those who had MST plus minimal cortical resection (p = 0.1698). There was no permanent neurological complication in this series. Conclusion: Patients with intractable epilepsy with independent seizure foci in both hemispheres can be safely treated with the approach described in this paper, and seizure control achieved by this approach is fairly satisfactory and similar to that reported in patients with surgery on one hemisphere.