Abstracts

To report supernumerary phantom limb as an ictal phnomenon. A 66 year old right handed biologist presented with a 4 year history of stereotypic spells. His attacks are characterized by a nonspecific feeling of anxiety and unsteadiness followed by a profound perception that he has developed a third upper extremity. The supernumary limb cannot be seen but is perceived as [quot]right handed[quot], is positioned directly in front of him, and that the fingers can be moved. The experience has sufficient reality that the patient has attempted to use the limb during automatic movements (e.g. to use the turn signal while driving; unsucessfully bracing himself against falling). These events last 2-5 minutes, ocasionally 10, and occur up to 6 times daily. Impaired consciousness or motor phenomenon have never occurred. The mental status examination revealed minor defects of immediate memory and attention but the neurologic examination was otherwise normal, including evaluation of parietal lobe function. The MRI scan disclosed periventricular and subcortical white matter ischemic change. The interictal EEG was normal. An ictal EEG (coincident with the perceived appearance of the third arm) disclosed a new 4-6 Hz polymorphic rhythm predominantly at CZ-C4 . An ictal HMPAO-SPECT scan demonstrated a restricted zone of increased perfusion in the right central-parietal area. Carbamazepine, lamotrigine, and levitiracetam have been poorly tolerated and without benefit. A supernumerary phantom limb may occur as an ictal accompaniment of parietal lobe epilepsy. A literature search found only 3 previous reports of similar phenomena, with none since 1968.