Functional Outcome after Microsurgery of Giant Olfactory Groove Meningoma

Background: Olfactory groove meningiomas arise in the midline along the dura of the cribriform plate and fronto-sphenoidal suture, accounting for approximately 10% of intracranial Meningiomas. The most common presenting symptoms are cognitive changes, headache, anosmia and bitemporal visual field loss. The surgical goal is gross total resection of the tumor whenever possible. Objectives: We conducted a retrospective study of twenty three patients with olfactory groove meningioma focused on long-term follow-up results after microsurgical treatment as well as clinical presentation, and surgical approaches. Patients and Methods: Clinical, radiological and surgical data in a consecutive series of twenty three patients with surgically treated giant olfactory groove meningiomas, were retrospectively reviewed. In all patients extensive preoperative and postoperative lateralised olfactory testing was performed using the “Sniffin’ Sticks” test battery, a psychometric testing tool. Ophthalmological evaluation included visual acuity, fundoscopy and visual fields while psychological evaluation included a Mini-Mental State Examination. Data were collected before, one and 48months after surgery. Results: the study included sixteen women and seven men (mean age 49 years). Symptoms were mental changes in 39.1%, visual impairment in 17.3% and anosmia in 13% of the patients. Preoperative neurological examination revealed deficits in olfaction in 71.4%, mental disturbances in 52.1% and reduced vision in 21.7% of the cases. Surgical approaches: a bifrontal craniotomy in ten, a pterional in three, and a unilateral frontal approach in seven. Extent of tumour resection according to Simpson’s classification system was grade I in 43.4% and grade II in 56.5% of the cases. After a mean follow up period of 18 months (range 1–3 years) by clinical examination and magnetic resonance imaging (MRI), 86.3% of the patients resumed normal life activity. Olfaction was preserved in 28.5% of patients in whom pre- and postoperative data were available. Both Mental and visual disturbances improved by 80 % of cases. Two recurrences (8.6%) were observed and had to be reoperated. Conclusion: Giant olfactory groove meningiomas are a challenge for neurosurgeons. Preservation of olfaction should be attempted in patients with normal or reduced smelling preoperatively. Improvement of preoperative cognitive changes and visual deficits without additional neurological deficits is the main aim of surgery. Microsurgical excision of giant olfactory groove meningiomas carries less incidence of morbidity and mortality.