Arachnoid cysts are benign cysts occurring in the intra-arachnoid space and containing cerebrospinal fluid. They constitute approximately 1 per cent of all intracranial masses. They are uncommon in the posterior cranial fossa. Common presenting symptoms include headaches, seizures, focal neurologic signs and vague dizziness. Magnetic resonance imaging is the preferred method of investigation, and the treatment for symptomatic cysts is generally surgical drainage.

We report the unusual presentation of a young patient with a posterior fossa arachnoid cyst that manifested in the form of isolated unilateral sensorineural hearing loss. The patient underwent posterior fossa craniotomy and marsupialization of the cyst. To our knowledge, posterior fossa arachnoid cyst presenting with isolated hearing loss alone has not been reported in the English literature. A review of the literature pertaining to posterior fossa arachnoid cysts, including the clinical features, diagnosis and management, is also presented.