Acoustic Neurinoma

Definition and Characteristics

Acoustic neurinomas (AN) are Schwann cell tumors originating from the vestibular portion of the eighth cranial nerve.

Prevalence

AN are the most common lesion of the cerebellopontine angle and constitute about 6% of all intracranial tumors. The incidence in the United States is 1 in 100,000 with 2,500 new cases diagnosed each year (US) [1].

Molecular and Systemic Pathophysiology

An AN is a slowly growing lesion which arises from Schwann cells surrounding the vestibular portion of the eighth cranial nerve. There are two forms known, sporadic and familiar cases (neurofibromatosis 2). The sporadic form constitutes over 90% and is not hereditary. NF2 is the only gene known to be associated with neurofibromatosis 2.

Unilateral hearing loss is the most common presenting symptom. Other possible symptoms are tinnitus, disequilibrium, vertigo, headache and aural fullness. In a later stage, facial numbness, facial weakness, diplopia, neuropathies of cranial nerves...