Arachnoid cyst presenting with sudden hearing loss.

Arachnoid cysts can occur at different intracranial sites, including the cerebellopontine angle (CPA). They often occur in childhood, in the posterior fossa. They may present with symptoms such as dizziness, tinnitus and hearing loss, or they may be asymptomatic. Presentation with sudden deafness is very rare. We report the unusual presentation of a 67-year-old male with CPA arachnoid cyst and the complaint of sudden-onset deafness. In this case, the cystic lesion at the CPA was found by magnetic resonance imaging of the brain. Pathology after retromastoid suboccipital craniotomy confirmed an arachnoid cyst. The treatment of this patient is discussed and the possible causes of CPA arachnoid cyst are briefly reviewed.