Olfactory groove meningiomas: functional outcome in a series treated microsurgically

Background. A systematic investigation of long-term follow-up results after microsurgical treatment of patients harbouring an olfactory groove meningioma, particularly with regard to postoperative olfactory and mental function, has rarely been performed. We reassessed a series of patients treated microsurgically for an olfactory groove meningioma in regard to clinical presentation, surgical approaches and long-term functional outcome. Method. Clinical, radiological and surgical data in a consecutive series of 56 patients suffering from olfactory groove meningioma were retrospectively reviewed. Findings. Presenting symptoms of the 41 women and 15 men (mean age 51 years) were mental changes in 39.3%, visual impairment in 16.1% and anosmia in 14.3% of the patients. Preoperative neurological examination revealed deficits in olfaction in 71.7%, mental disturbances in 55.4% and reduced vision in 21.4% of the cases. The tumour was resected via a bifrontal craniotomy in 36, a pterional route in 13, a unilateral frontal approach in 4 and via a supraorbital approach in 3 patients. Extent of tumour resection according to Simpson's classification system was grade I in 42.9% and grade II in 57.1% of the cases. After a mean follow-up period of 5.6 years (range 1-13 years) by clinical examination and magnetic resonance imaging (MRI), 86.8% of the patients resumed normal life activity. Olfaction was preserved in 24.4% of patients in whom pre- and postoperative data were available. Mental and visual disturbances improved in 88 and 83.3% of cases, respectively. Five recurrences (8.9%) were observed and had to be reoperated. Conclusions. Frontal approaches allowed better resection of tumours with gross infiltration of the anterior cranial base, tumours extending into the ethmoids or nasal cavity and in cases with deep olfactory grooves. Preservation of olfaction should be attempted in patients with normal or reduced smelling preoperatively.