OLFACTORY EPILEPTIC AURAS

Background: Olfactory epileptic auras are rare, constituting about 0.9 % of all auras, and are typically described as unpleasant. They have u sually been associated with tumors, but in some recent studies they ha ve not. Methods: We identified 13 patients (7 male, 6 female) with olf actory epileptic auras from 1423 patients with partial epilepsy evalua ted for intractable seizures between 1991 and 1996. All had routine EE Gs and MRI. Twelve underwent prolonged video-EEG monitoring. Results: Olfactory sensations were of various types but unpleasant in only seve n. Auras evolved to complex partial seizures (automotor, hypermotor, o r dialeptic seizures) in 12 patients, with further evolution to genera lized tonic-clonic seizures in three and aphasic seizures in one patie nt. The EEG focus was localized to the mesial temporal region in all. Ten patients had a mesial temporal tumor; in one patient, it extended to the superior temporal gyrus, and in another, the frontal lobe. The tumor involved only the amygdala in two patients and both amygdala and hippocampus in six; none had hippocampal involvement alone. Surgery w as performed in nine patients. All except one with partial tumor resec tion had a seizure-free outcome. This patient also became seizure-free after repeat surgery to remove residual tumor tissue in the amygdala. Conclusions: Olfactory auras are not necessarily unpleasant. The amyg dala is the most likely symptomatogenic zone of olfactory auras. Tumor s are the commonest etiology; mesial temporal sclerosis is a relativel y rare cause.