Abstracts

Rationale: An anterior temporal lobectomy (ATL) is a proven therapy for select patients with drug resistant temporal lobe epilepsy (TLE). Although efficacious, ATLs are not without risk. In dominant ATLs, these include decline in verbal memory, naming, and (rarely) postoperative anomia. It is often assumed that right handed patients have commitment of the left hemisphere to language. We present a case of a right handed patient with right TLE and language lateralized to the right hemisphere.Methods: Case report and literature review.Results: A 31 year old right handed gentleman with no family history of left handedness presented with medically refractory seizures. Since 2003, he had suffered from seizures consisting of an aura of a strange feeling, followed by behavioral arrest, oral automatisms, and occasional secondary generalization. These persisted despite trials of phenytoin and levetiracetam. Brain magnetic resonance imaging (MRI) revealed a lesion in the right temporal lobe with high T2 and low T1 signal concerning for a low grade glioma, dysembryoplastic neuroepithelial tumor, pleomorphic xanthoastrocytoma, or ganglioglioma. Although scalp EEG monitoring recorded seizures of right and left temporal lobe onset, intracranial monitoring with bitemporal depth electrodes confirmed seizure onset to be exclusively right mesial. As part of his presurgical workup, the patient underwent a functional MRI (fMRI) for language lateralization. Surprisingly, his fMRI revealed language to be lateralized to the right hemisphere. On questioning, the patient denied any history of left handedness prior to seizure onset or having to switch handedness in childhood. He underwent two Wada tests, both of which confirmed right hemisphere dominance for language. There was an indication that the left hemisphere may have contained some limited expressive and receptive language functions, as he continued to vocalize, perform verbal commands, and stated one object name following the right injection. The second (bilateral) Wada demonstrated that the right hippocampus continued to encode and consolidate new memories. He scored 1/8 during memory testing conducted after a right injection; he scored 6/8 following a left injection. An investigational memory fMRI revealed bilateral hippocampal activation with two word association tasks. Based on such results, it was decided that a standard right ATL might carry a significant risk of postoperative memory and language deficits. The patient is currently weighing the risks and benefits of ATL before making a firm decision on treatment.Conclusions: Although rare, it is possible to observe atypical right hemispheric language lateralization in right handed patients, even with onset of neurologic dysfunction beyond childhood. Our case demonstrates that it is imperative for physicians to screen for such variants when performing epilepsy surgery evaluations, particularly given that such screening can be done noninvasively. Without such data, it is impossible to counsel patients on the true risk of postoperative memory and language deficits.