Occult, bilateral anterior sacral and intrasacral meningeal and perineurial cysts: case report and review of the literature. None of the more than 180 cases of anterior sacral meningocele reported in the past 150 years has been bilateral, and only two have been associated with occult intrasacral meningocele. We report a unique case of bilateral anterior sacral cysts, communicating with the subarachnoid space, associated with occult intrasacral meningeal and perineurial (Tarlov's) cysts, in an asymptomatic woman. The pertinent clinical and diagnostic imaging literature is reviewed. 