FREQUENCY OF UNEXPLAINED MENINGEAL ENHANCEMENT IN THE BRAIN AFTER LUMBAR PUNCTURE

PURPOSE: To examine the hypothesis that lumbar puncture alone may caus e meningeal enhancement in the brain. METHODS: We prospectively review ed the brain MR examinations of all patients from a 6-month period who were studied within 1 month after lumbar puncture. We also retrospect ively reviewed all cases of dural-arachnoidal enhancement in the brain from the preceding 18-month period. RESULTS: In the prospective group , only one case out of 97 enhanced brain MR examinations after lumbar puncture did not have a clear cause for dural-arachnoidal enhancement. In the retrospective group, only one case out of 11 with enhancement was not clearly explained. CONCLUSIONS: Dural-arachnoidal enhancement in the brain after lumbar puncture is uncommon, if it occurs at all, a nd lumbar puncture as a cause of enhancement should be considered a ra re diagnosis of exclusion.