Insular lesionectomy for refractory epilepsy: management and outcome

Surgical treatment of deep-seated insular lesions causing refractory epilepsy is thought to be difficult due to the complicated accessibility and close proximity of eloquent areas. Here we report our experience with insular lesionectomies. Twenty-four patients (range 1-62 years, mean 27) who underwent epilepsy-surgery for a lesion involving the insular region, were identified from the epilepsy surgery data bank. We analysed pre-surgical diagnostics, surgical strategy and postoperative follow up concerning functional morbidity and seizure outcome (range 12-168 months, mean 37.5). Eight patients had pure insular lesions, in 16 cases the lesion extended either to the frontal (n = 3) or temporal lobe (n = 8) or was multilobar (n = 5). Sixteen resections (66.7%) were done on the right side. Six patients required invasive EEG-recording, three patients received intra-operative electrocorticography. In seven patients only subtotal resection of the insular lesion was possible due to involvement of eloquent areas. Thirteen patients suffered from glial/glioneural tumours (WHO grades I-III), 11 from non-neoplastic lesions. Postoperatively, one patient had a hemihypesthesia and one patient had a deterioration of a pre-existing hemiparesis; two patients had a hemianopia as calculated deficit (mild permanent morbidity 16.6%). According to the ILAE-classification, 15 patients were completely seizure free (62.5%, ILAE 1). Around 79.2% had satisfactory seizure outcome (ILAE 1-3). In selected patients an individually tailored lesionectomy of insular lesions can be performed, which is acceptably safe and provides a high rate of satisfactory seizure relief. Even subtotal resection can result in good seizure control.