Outcome after cortico-amygdalo-hippocampectomy in patients with severe bilateral mesial temporal sclerosis submitted to invasive recording.

Introduction: Although some degree of bilateral hippocampal involvement might be frequent in patients with temporal lobe epilepsy, severe bilateral mesial temporal sclerosis (MTS) is very rare. We present our experience while treating patients with severe bilateral MTS submitted to invasive recordings.

Methods: Nine adult patients were studied. All patients had simple and complex partial seizures. All patients had bilateral independent interictal temporal lobe spiking and non-lateralizing video-EEG findings. MRI showed severe bilateral MTS and no other brain lesion. All patients had severe verbal and non-verbal memory deficits. All patients were submitted to invasive recordings after bilateral subdural grids implantation. Cortico-amygdalo-hippocampectomy (CAH) was performed in all patients on the side suggested by invasive recording. Follow-up time ranged from 5 to 10 years.

Results: Invasive video-EEG showed exclusively unilateral seizure onset in seven patients; in two patients, seizures originating from both temporal lobes were found (80% of them originated from one side). Five patients were submitted to left and four to right CAH. Seven patients were rendered seizure-free after surgery (Engel I); the other two were rated as Engel II. There was no additional memory decline. There was no surgical morbidity or mortality. Pathological examination showed MTS in all patients.

Discussion: Good surgical outcome (77% seizure-free patients) could be obtained even in this apparently unsuitable group of patients. All patients benefit from the procedure. We did not see any cognitive decline in our patients with severe bilateral MTS. Patients with severe bilateral MTS would need invasive recordings despite any findings during surface video-EEG.