Vestibular Schwannoma (Acoustic Neuroma)

Eighth nerve schwannomas are among the most common of intracranial tumors

The lesions arise within the internal auditory canal and gradually grow to involve the cerebellopontine angle, eventually compressing the pons and resulting in hydrocephalus

Most are unilateral

About 5% are associated with hereditary syndrome, neurofibromatosis type 2

Any individual with a unilateral or asymmetric sensorineural hearing loss should be evaluated for an intracranial mass lesion

Other lesions of the cerebellopontine angle, such as meningioma and epidermoids, may have similar audiovestibular manifestations

Typical auditory symptoms are unilateral hearing loss with deterioration of speech discrimination exceeding that predicted by the degree of pure-tone loss

Nonclassic presentations, such as sudden unilateral hearing loss, are fairly common

Vestibular dysfunction more often takes the form of continuous dysequilibrium than episodic vertigo

Diagnosis is made by enhanced MRI

Depends on such factors as patient age, underlying health, and size of the tumor

Consists of

• Observation

• Microsurgical excision

• Stereotactic radiotherapy

Bevacizumab (vascular endothelial growth factor blocker) has shown promise in treating neurofibromatosis type 2