Chronic meningitis: the role of meningeal or cortical biopsy.

Meningeal and cortical biopsies were evaluated in 37 patients (25 men and 12 women; mean age, 54 yr) who had chronic meningitis of an unknown cause between 1985 and 1993 (the era of magnetic resonance imaging). Magnetic resonance imaging with gadolinium contrast was the most useful diagnostic imaging technique, demonstrating meningeal enhancement in 15 of 32 patients (47%). Only 2 of 32 (6%) computed tomographic scans revealed enhancement. A definitive diagnosis was made in 16 of 41 biopsies (39%), but in cases where enhancement was present on either magnetic resonance imaging or computed tomography, a diagnosis was obtained in 80% (12 of 15 cases). Only 2 of 22 biopsies (9%) from nonenhancing regions were diagnostic. Although the locations of enhancement were distributed evenly, biopsies through suboccipital and pterional craniotomies gave the highest diagnostic yields (50%). Furthermore, if the biopsies were obtained from enhancing regions, the yield of these two approaches increased to 84 and 100%, respectively. Of 18 cases in which biopsy samples were taken from both the meninges and cortex, only 1 had cortical involvement alone. The meninges were therefore diagnostic in 15 of the 16 definitive diagnostic cases (94%). Second biopsies were necessary in four cases, of which the three biopsies from enhancing regions were diagnostic. The most frequent causes of chronic meningitis were sarcoid (31%) and metastatic adenocarcinoma (25%).(ABSTRACT TRUNCATED AT 250 WORDS)