Olfactory function in patients with olfactory groove meningioma

Objectives-Olfactory meningiomas are rare benign tumours and represent abou t 12% of all basal meningiomas. Anosmia is thought to be among the first sy mptoms, even though patients often present with headaches or visual problem s. However, so far no detailed physophysical tests of olfactory function ha ve been performed in a large number of those patients. Methods-Twelve patients (five men, seven women; mean age 52 years) with olf actory meningiomas were examined. In all patients extensive preoperative an d postoperative lateralised olfactory testing was performed using the "Snif fin' Sticks" test battery, a psychometric testing tool. In eight cases the meningioma was lateralised (five left, three right), in four patients a bil ateral meningioma was found. In addition to a detailed ear, nose, and throa t examination MRI was performed in all patients. Results-In preoperative testing six patients were found to be anosmic on th e side of the tumour, two were hyposmic. Four patients were normosmic. Post operative investigations showed lateralised anosmia in four patients on the operated side, three were normosmic on the contralateral side and one hypo smic. The remaining eight patients were completely anosmic postoperatively. Conclusions-(1) Contrary to expectations, olfactory testing seems to be of little help in detecting olfactory meningiomas. (2) The likelihood of norma l postoperative olfactory function contralateral to the tumour was high whe n the tumour was less than 3 cm in diameter and preoperative normosmia had been established. (3) Preservation of olfactory function ipsilateral to the tumour seems to be extremely difficult, irrespective of tumour size or sur gical approach.