gms | German Medical Science

Objective: Epilepsies originating from the occipital area account for a small percentage of the extratemporal epilepsies. Most series reported so far are small, and others are not exclusively focused on the occipital lobe. Thus, the preoperative planning, surgical strategies, pathologic basis and prognosis for OLE patients remain to be elucidated.

Methods: Patients were prospectively entered in a data bank since 1990. Data bank information was screened, and a group of 44 patients with occipital involvement was defined. Charts, surgical reports, pathology and MR data were reviewed. Seizure control was determined at the last regular outpatient exam or with standardized telephone interviews. Seizure outcome was classified according to Engel’s score (I – IV).

Results: 29 (16m,13f) patients with pure OLE were included, making up 9.9% of 292 patients undergoing operation for extratemporal epilepsies. The majority (24 pat, 83%) had complex partial seizures, and 20 patients (69%) had experienced generalized seizures. Two patients had a history of trauma, one of perinatal asphyxia, and 3 patients had had prior intracranial surgery. All patients revealed a lesion upon MRI. 12 patients (41%) underwent invasive EEG monitoring with implanted electrodes and intraoperative electrocorticography was performed in 11 patients. All patients had occipital lesionectomies, 6 patients additional MST. Histopathology revealed 7 gangliogliomas (24%), one low-grade ependymoma (3%), 7 vascular malformations (24%), 5 dysplasias (17%), and 9 gliotic scars (31%). One patient had two pathologies. One patient suffered a postoperative hemorrhage with a mild hemiparesis (3%) but there was no mortality. Visual field deficits were the most common neurological deficits present in 11 patients preoperatively (38%). 6 patients (21%) showed new and 3 patients (10%) aggravated visual field deficits after surgery. Mean follow-up was 38 months. 21 patients were seizure free (72% Engel I), 2 had rare seizures (7% Engel II), 3 improved more than 75% (10.5% Engel III), and 3 had no worthwhile improvement (10.5% Engel IV).

Conclusions: OLE is a rare, but typical entity of focal epilepsy. Promising results were obtained in 79% of patients in our series. Postoperative visual field deficits have to be expected in a significant number of patients.