benign tumour on the vestibulocochlear nerve (also called acoustic nerve) near its point of entry into the inner ear. The tumour, though benign, may spread into the brain cavity if not detected in its first stages. Early symptoms include mild unilateral hearing impairment, tinnitus (ringing in the ear), and sometimes dizziness. If the tumour has extended into the brain cavity, headache and paralysis are experienced. Treatment of acoustic neuroma is surgical excision.