Odor perception in temporal lobe epilepsy patients with and without temporal lobectomy

The investigation employed monorhinic (single nostril) olfactory testing to decide whether patients with unilateral anterior temporal lobe resection ( N = 16) and patients with unoperated temporal lobe epilepsy ( N = 18) have impaired ability to detect, remember, and identify odors. A shape memory task accompanied the odor memory task for comparison. The lobectomy patients showed a minor bilateral depression of absolute sensitivity but still fell within the clinically normal range. The lobectomy patients showed impairment of odor recognition memory but strictly via the nostril ipsilateral to the resected lobe. A similar ipsilateral-contralateral asymmetry characterized the performance of these patients in odor identification. In that case, however, performance via the contralateral nostril showed some impairment too. Nonsurgery patients also exhibited some impairment in odor identification, but bilaterally. Finally, both groups of patients fell somewhat below normals in recognition memory for amorphous shapes. The various results implied that temporal lobe epilepsy alone takes some toll on olfactory information processing and that temporal lobe resection exacerbates the problem, but only on the side of surgery.