Spinal arachnoid cysts have frequently been found amid arachnoid adhesions. Various names have been used to describe this condition, such as intradural cysts of the spinal meninges, circumscribed serous spinal meningitis, leptomeningeal cysts, localized adhesive spinal arachnoiditis, arachnitis adhesive circumscript,arachnoitis cloisonée, arachnoid cysts, chronic spinal meningitis, and meningitis serosa circumscripta spinalis. The arachnoid cysts found in such instances were not true cysts but merely fluid loculated in arachnoid scar tissue, binding the dura to the surface of the spinal cord. One or more such cysts may be noted in the adherent area, but they are not numerous and the distribution is not extensive. The primary cause of symptoms in these cases is the arachnoid adhesion caused by infection, chemical irritation, or trauma. In only a few of the recorded series of cases are the cysts extensively distributed in the arachnoid space. These have been described as "adhesive arachnoiditis of