Acoustic Neuroma NY: Long Island Neurosurgeon
Acoustic neuroma (or Vestibular Schwannoma) is a benign primary intracranial tumor, or brain tumor, of the myelin forming cells called "Schwann cells" (Schwannoma) of the 8th cranial nerve --- also known as the acoustic nerve, (or more properly the vestibulocochlear nerve).
The term "acoustic neuroma" is actually a misnomer since the tumor never arises from the acoustic division of the vestibulocochlear nerve (cranial nerve VIII) and the tumor is not a neuroma but a schwannoma.
Approximately 3000 cases are diagnosed each year in the United States with an incidence of about 1 in 100,000. Incidence peaks in the fifth and sixth decades and both sexes are affected equally.
Earliest symptoms of acoustic neuromas include hearing loss/deafness, disturbed sense of balance and altered gait, vertigo with associated nausea and vomiting, and pressure in the ear, all of which can be attributed to the disruption of normal vestibulocochlear nerve function. Additionally more than 80% of patients have reported tinnitus (most often a unilateral high-pitched ringing, sometimes a machinery-like roaring or hissing sound, like a steam kettle).
Large tumors that compress the adjacent brainstem may affect other local cranial nerves. Involvement of the 7th cranial nerve (facial nerve) may lead to facial weakness, sensory impairment, and impairment of glandular secretions; involvement of the 5th cranial nerve (trigeminal nerve) may lead to loss of taste and loss of sensation in the involved side's face and mouth. Involvement of the 9th and 10th cranial nerves are uncommon, but may lead to altered gag or swallowing reflexes.
Even larger tumors may lead to increased intracranial pressure, with its associated symptoms such as headache, vomiting, and altered consciousness.
Contrast-enhanced CT will detect almost all acoustic neuromas > 2.0 cm in diameter and project further than 1.5 cm into the cerebellopontine angle. Those tumors that are smaller may be detected by MRI with gadolinium enhancement. Audiology and vestibular tests should be concurrently evaluated using the Weber's and Rinne's test to assess for sensorineural versus conduction hearing loss.
Indicated treatments for acoustic neuroma include surgical removal and radiotherapy.