Unexpected right hemisphere language representation identified by the intracarotid amobarbital procedure in right-handed epilepsy surgery candidates

The intracarotid amobarbital procedure (IAP) is used for language lateralization in the presurgical evaluation for intractable epilepsy. Some epilepsy surgical centers forgo IAP for right temporal lobectomies in right-handed patients with no personal/family history of left-handedness, implying that right hemisphere language representation does not occur in these patients. To test this hypothesis, a retrospective analysis was performed on 156 consecutive epilepsy surgery candidates who underwent IAP. Of the 156 candidates, 122 were right-handed, and 55 of the 122 demonstrated right hemisphere seizure focus. Right hemisphere language representation was found in 22 of 55 patients, with two demonstrating significant right hemisphere language despite a right hemisphere seizure focus and no family history of left-handedness. Only 1 of 156 patients undergoing IAP experienced permanent neurological complications. Although relatively uncommon, right hemisphere language representation may occur more frequently than complications from cerebral angiography and, therefore, presurgical IAP is recommended for all epilepsy surgery candidates regardless of handedness to minimize the risk of severe language decline.