Clinical diagnosis of insular epilepsy is greatly facilitated by the identification of an insular epileptogenic lesion, although nonlesional cases are frequent. Among 25 patients who underwent nontumoral epilepsy surgery involving operculo-insular resection, presurgical magnetic resonance imaging (MRI) of the operculo-insular area was normal or revealed questionable nonspecific findings in 18 (72%).17 Malformations of cortical development were commonly associated with medication resistant seizures.18