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Vestibulocochlear Nerve

nervus vestibulocochlearis (CN VIII)

The vestibulocochlear nerve (CN VIII) has two distinct divisions: the cochlear nerve (arising from the spiral ganglion in the modiolus, carrying hearing from the organ of Corti) and the vestibular nerve (arising from Scarpa's ganglion in the internal auditory canal, carrying balance from the semicircular canals and otolith organs). They travel together in the internal auditory canal before entering the brainstem at the cerebellopontine angle.

Region: Head & Skull

Clinical Relevance

Clinical Notes

Acoustic neuroma (vestibular schwannoma) arises most commonly from the inferior vestibular nerve in the internal auditory canal, producing progressive unilateral sensorineural hearing loss, tinnitus, and vertigo. Small tumours confined to the IAC are managed by observation, radiosurgery, or hearing-sparing middle fossa or retrosigmoid surgery. Large tumours compressing the brainstem require translabyrinthine or retrosigmoid resection. CN VIII monitoring during surgery uses BAER (brainstem auditory evoked response) to monitor cochlear nerve function.

Pathology

Common Injuries & Conditions

Vestibular Schwannoma Compressing CN VIII

Vestibular schwannoma expanding from the inferior vestibular nerve in the internal auditory canal produces ipsilateral high-frequency sensorineural hearing loss and vestibular hypofunction on caloric testing; gadolinium MRI demonstrates the enhancing tumour at the cerebellopontine angle, and treatment is determined by tumour size, growth rate, and patient hearing status.