ABSTRACT
INCIDENCE/EPIDEMIOLOGY Incidence Meningiomas account for 32% of all primary brain tumors and represent the second most common central nervous system (CNS) neoplasm in adults after gliomas (1). The incidence of meningioma is 4.7 cases per 100,000 person-years, and women outnumber men by 2.1:1. The median age at diagnosis is 63 and the incidence of meningioma increases with increasing age. The incidence of diagnostically and nondiagnostically confirmed meningioma has increased between 1985 and 1999, with the incidence of nondiagnostically confirmed meningioma increasing by 4.1% per year. This trend likely reflects the increaseduse ofMRI in the diagnosis of incidental meningioma (2). Data from the population-based Rotterdam study found incidentalmeningiomas in 18 out of 2000 (0.9%) MRI scans performed. These incidental meningiomas ranged from 5 mm to 60 mm in diameter and the prevalence was 1.1% in women and 0.7% in men (3). Intracranial meningiomas outnumber spinal meningiomas by approximately 10:1 (4). Pediatric meningiomas are rare and comprise less than 2% of all meningiomas and less than 5% of all pediatric brain tumors (5,6). The most common locations for intracranial meningiomas are parasagittal, sphenoid ridge, and convexity. Forty percent of allmeningiomas arise from the base of the anterior, middle, or posterior fossa and are the most common skull base tumors. Sphenoid wing meningiomas make up about half of these; tuberculum sella and olfactory groove tumors the other half. Ectopic meningiomas have been described in the orbit, paranasal sinuses, skin, subcutaneous tissues, lung, mediastinum, and adrenal glands. Table 1 details the common sites for meningiomas and their incidence.
Etiology Trauma Several case-control studies have shown an elevated odds ratio for the development of meningioma in patients with a history of head trauma, though no clear association has been found to date (7-10). A recent population-based case-control study of 200 patients with meningioma found an elevated odds ratio of 2.62 for the development of meningioma given a history of head trauma (11). In patients with a history of head trauma occurring 10 to 19 years prior to the date of diagnosis, an odds ratio of 4.33 was found. Yet other studies have found no such elevated risk (12,13). Recall bias has been suggested as a confounding factor limiting the effectiveness of case-control studies. Further epidemiological studies are necessary to validate and delineate a relationship.
