Arachnoid cyst producing recurrent neurological disturbances.

A patient with an arachnoid cyst of the posteriro fossa experienced repeated episodes of transient right upper extremity numbness and weakness. Review of the literature indicates that arachnoid cysts of the posterior fossa and spinal canal as well as extradural spinal cysts may present with symptoms of transient neurological deficit which often suggest the diagnosis of multiple sclerosis.