Abstracts

Rationale: The insular region has long been neglected in the investigation and treatment of refractory epilepsy because of its location in the depth of the Sylvian fissure. Furthermore, surgery in the insular region is rarely performed because of the risk of injury to the opercula, the arteries transiting on the surface of the insula and the deep structures such as the basal ganglia and the internal capsule. Methods: A retrospective study of patients operated for insular epilepsy over the last 10 years was undertaken. When MRI and other non invasive investigation were not conclusive, intracranial electrodes guided by neuronavigation were implanted to confirm the localization of the epileptic foci. Results: Ten patients had insular surgery: seven for refractory epilepsy with no tumor and three for tumors associated with seizures. Four of the resections were performed in the left hemisphere. After an average follow-up of 54 months (range 12 to 120 months), Engel Ia outcome was achieved in all of the patients, except one patient who had an Engel III outcome after initial partial insular resection. He became seizure-free (Engel Ia) following insular gamma-knife treatment. Following surgery, the majority of patients suffered from minor reversible hemiparesis that disappeared completely within a few months. There was no surgical mortality. Conclusions: Insular surgery is both safe and beneficial when it is well planned and performed with modern microsurgical techniques and good anatomical knowledge. Insulectomy is associated with little permanent morbidity and a high rate of seizure control. To our knowledge, this is the first series of insulectomy predominantly performed for refractory epilepsy since Penfield.