Rare, benign tumour of the CN VIII nerve sheath that arises in internal auditory meatus

Aetiology

• Equal sex distribution
• Aetiology unknown but may be associated with extensive exposure to excessively loud noise
• If bilateral and young, consider neurofibromatosis type 2

Pathophysiology

• Associated with vestibular portion of CN VIII
• Occur within temporal bone, represent 80-90% of cerebellopontine angle tumours
• 95% are sporadic and unilateral
• Gross appearance - circumscribed tan/white/yellow mass
• Histology - encapsulated, two growth patterns (Antoni A and Antoni B)

Clinical features

• Progressive sensorineural unilateral hearing loss and tinnitus
• Imbalance in larger tumours
• Facial numbness can occur due to compression of the trigeminal nerve as the tumour enlarges

Investigations

• MRI

Management

• Surgical excision is the definitive management
• Small lesions that are not growing may be monitored (MRI) - initially with a 6 month interval