Acoustic neuromas (vestibular schwannomas) are benign Schwann cell tumors that typically arise from the vestibular portion of the eighth cranial nerve. The acoustic neuroma is the most common tumor of the cerebellopontine angle. The most common presenting symptoms are unilateral sensorineural hearing loss, tinnitus and imbalance. Ninety-five percent of AN are unilateral and occur as a random event. About 5 percent of patients have bilateral AN inherited as part of neurofibromatosis type II (NF II) (central von Recklinghausen's disease).
This dominant autosomal disorder of chromosome 22 is associated with acoustic neuromas, meningiomas and gliomas. Neurofibromatosis I is not usually associated with acoustic neuromas. The acoustic neuroma occurs equally between men and women and most frequently present in the fourth and fifth decades.
Clinical Diagnosis of Acoustic Neuroma: Unilateral loss of hearing is the most common initial symptom
The diagnosis of an acoustic neuroma is often triggered by a patient’s symptoms. The most common presenting feature of acoustic neuromas, occurring in 90 percent of patients, is unilateral hearing loss. When pure tone audiometry is used, the most common finding is high frequency hearing loss. The hearing loss is progressive in most patients, but in approximately 12 percent of patients the hearing loss may occur suddenly. Other symptoms of the acoustic neuroma include asymmetric tinnitus (ringing in the ear), dizziness and disequilibrium (difficulty with balance).