Arachnoid cyst of the cerebellopontine angle causing isolated acute hearing loss, with literature review.

Abstract

Dear Editor, We present the case of an arachnoid cyst of the cerebellopontine angle which presented with unilateral acute sensorineural hearing loss as an initial and only symptom. Posterior fossa arachnoid cysts generally remain asymptomatic or cause vague and non-specific symptoms. Presentation with acute deafness is very rare. Only five posterior fossa arachnoid cysts presenting with acute hearing loss have been reported previously [2–5, 7]. We report the first case, to our knowledge, of complete recovery from unilateral acute sensorineural hearing loss following surgery in a patient with a cerebellopontine angle (CPA) arachnoid cyst. A 25-year-old woman presented with acute rightsided hearing loss that was her only complaint at that moment. She noticed the hearing loss when she woke up in the morning 2 days before admission. She did not experience headache or vestibular symptoms. There was no history of ototoxicity, recent trauma, infectious disease or neurological disorders. The otolaryngological and vestibular findings were within normal limits. Neurological examination was also normal. All haematological findings were within normal limits. Audiometry showed sensorineural hearing loss with an average of 77 dB on the right side, mainly for the high frequencies (Fig. 1). Magnetic resonance imaging (MRI) was performed to rule out retrocochlear lesion involving the cranial nerves or their nuclei. MRI scans revealed a fluid containing cystic lesion (measuring 30×25×15 mm), which located at the right CPA with compression of the VIII cranial nerve and brainstem. The cystic lesion showed no enhancement after gadolinium injection (Fig. 21). The diagnosis of arachnoid cyst was made by the typical MRI findings. Operation was suggested and the patient underwent microsurg ica l resec t ion of the cys t wal l s v ia retrosigmoid suboccipital craniotomy. Postoperatively, the patient’s sensorineural hearing loss improved.