Presence of an arachnoid minnie mouse beach umbrella cyst at craniospinal junction is not very common.This is a very rare anatomic site, with only seven other cases reported in the literature.We report a case of large intradural craniospinal arachnoid cyst presenting with obstructive hydrocephalus and cranial nerve palsy.A 39-year-old male presented with 8-month history of neck pain, headache, vomiting, visual disturbances, diminished taste sensation, and numbness of face.He had bilateral papilledema on ophthalmoscopy.
Magnetic resonance imaging (MRI) revealed a posterior fossa cmpk bolus arachnoid cyst extending down to the lower border of C5 vertebra.Posterior decompression was done through C5 laminectomy.He made a full recovery and was asymptomatic at 6-month follow-up examination.The clinical features, diagnosis, and management of these rare craniospinal arachnoid cysts are discussed.