Craniospinal arachnoid cyst: case report

We encountered a rare case of craniospinal arachnoid cyst. A 54-year-old woman was admitted to our clinic for headache, posterior nuchal pain, and vomiting, which had started one month before. On admission she was drowsy, and neurological examination revealed papilledema and prompt deep tendon reflexes bilaterally. T1 weighted images of MRI revealed a homogeneous, round, low density mass in the left cerebellar hemisphere which extended down on the dorsal side of the spinal cord to the level of C2. It was high intensity on T2 weighted images and was not enhanced by Gd-DTPA. The fourth ventricle was compressed and obstructed and hydrocephalus was observed. An operation was performed via a left suboccipital craniectomy with C1 laminectomy. A large cyst was located in the left cerebellar hemisphere, and it extended into the spinal canal down to the C2 level where the cyst compressed the spinal cord right-anteriorly. The content of the cyst was xanthochromic fluid. After the removal of as much of the cyst as possible, the flattened tonsil was seen just dorsal to the medulla. The cyst extended into the cerebellar hemisphere via the widened fissura secunda. The arachnoid of the cisterna magna was incised and communication between the cisterna magna and the cyst was made. The cyst was markedly reduced on the following day, and disappeared on the 50th postoperative day. The patient was discharged without neurological deficit. Pathological diagnosis of the cyst wall in the cerebellum was that the molecular layer of the cerebellar cortex was covered by arachnoid membrane, which indicated arachnoid cyst. Five such cases have been reported apart from this one. The therapy is the extirpation of the cyst wall and making communication between the arachnoid cyst and the subarachnoid space. The etiology of craniospinal arachnoid cyst is not well known but postoperative prognosis is good.