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Chronic meningitis: the role of meningeal or cortical biopsy
T M Cheng1, B P O'Neill, B W Scheithauer
1Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota.
Abstract:
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)
Insights
Magnetic resonance imaging (MRI) with contrast is crucial for diagnosing chronic meningitis. Biopsies from enhancing regions identified via MRI significantly increase diagnostic yield, with meningeal biopsies being most effective.
Area of Science:
- Neurology
- Radiology
- Pathology
Background:
- Chronic meningitis of unknown cause presents diagnostic challenges.
- Early diagnostic imaging techniques were limited in identifying meningeal abnormalities.
Purpose of the Study:
- To evaluate the diagnostic utility of magnetic resonance imaging (MRI) and computed tomography (CT) in patients with chronic meningitis.
- To determine the effectiveness of biopsy location and enhancement patterns in achieving a definitive diagnosis.
Main Methods:
- Retrospective analysis of 37 patients with chronic meningitis between 1985 and 1993.
- Evaluation of meningeal and cortical biopsies.
- Correlation of diagnostic yield with imaging findings (MRI with gadolinium contrast and CT) and biopsy location.
Main Results:
- MRI demonstrated meningeal enhancement in 47% of patients, while CT showed enhancement in only 6%.
- Biopsies from enhancing regions yielded a diagnosis in 80% of cases, compared to 9% from non-enhancing regions.
- Meningeal biopsies were diagnostic in 94% of definitive cases, and specific surgical approaches (suboccipital and pterional craniotomies) targeting enhancing areas showed high diagnostic yields (84-100%).
- Sarcoidosis (31%) and metastatic adenocarcinoma (25%) were the most common causes.
Conclusions:
- MRI with gadolinium contrast is a superior imaging modality for detecting meningeal abnormalities in chronic meningitis.
- Targeted biopsies of enhancing meningeal regions, particularly via suboccipital or pterional approaches, significantly improve diagnostic accuracy.
- Meningeal involvement is more common than cortical in chronic meningitis.