Olfactory groove meningiomas: a retrospective study on 59 surgical cases.

We report here a retrospective study of 59 consecutive patients with olfactory groove meningiomas admitted and operated on between 1991 and 2008. Our goal was to characterize clinical features, treatment strategies, and outcome of these lesions. The surgical resection grade, the histological type and the presence of recurrences in the follow-up period were analyzed. Maximum tumor diameter determined by preoperative magnetic resonance imaging (MRI) examinations was between 2 and 11 cm. In 38 surgical procedures (64.4%), the tumor was removed through a bilateral subfrontal approach, in 12 (20.3%) a unilateral subfrontal approach was used, and in nine procedures (15.3%) a pterional approach was performed. The average age at presentation was 52 years (age: 20-76 years) and the sex ratio was 1.45:1 (females/males). According to Simpson's grading system, the degree of tumor removal was: grade I in 14 cases (23.8%), grade II in 38 cases (64.4%), grade III in four cases (6.8%) and grade IV in three cases (5%). Fifty-six patients had benign meningiomas (94.9%) and three patients had atypical meningiomas (5.1%). Two patients (3.4%) died from pulmonary embolism and bronchopneumonia. There were recurrences in six patients (10.1%), between 9 months and 12 years (mean 7.2 years) after surgery. The olfactory groove is a relatively frequent location for intracranial meningiomas, accounting for 9.1% of all intracranial meningiomas in our experience. Olfactory groove meningiomas tend to be clinically silent tumors until they are very large when symptoms or other abnormalities become evident. A surgical procedure adapted to the size and the extension of the tumor combined with microsurgical techniques allows total meningioma removal with good neurological outcome.