One sentence: The vestibular nerve is a special sensory nerve that balances information from the semicircular canals, and its anatomy is best visualized in relation to the temporal bone (Fig. 13.1) and the vestibular organ (Fig. 13.2).

Genetic testing

NCV/EMG

Laboratory

Imaging

Other

Biopsy

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Impulse test

 
Fig. 13.1
An anatomical diagram of the temporal bone numbers the tympanic cavity, external auditory meatus, bony labyrinth, and eustachian tube in the ascending order.

Temporal bone. (1) Tympanic cavity, (2) external auditory meatus, (3) bony labyrinth, (4) eustachian tube

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Fig. 13.2
An anatomical diagram of the vestibular nerve numbers the following parts in ascending order. Superior semicircular canal, lateral semicircular canal, posterior semicircular canal, utriculus, sacculus, spiral ganglia. Positions of nerves in the internal auditory meatus are also specified.

Vestibular nerve. (1) Superior semicircular canal, (2) lateral semicircular canal, (3) posterior semicircular canal, (4) utriculus, (5) sacculus, (6) spiral ganglia. Positions of nerves in the internal auditory meatus: a facial nerve, b superior vestibular nerve, c cochlear nerve, d inferior vestibular nerve

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Symptoms

Dizziness, vertigo (“spinning” and tilting), nausea/vomiting, imbalance, and falling.

Signs

Lesions result in abnormal eye movements and balance problems with stance, gait, and equilibrium abnormalities.

Specific symptoms: Vertigo, nystagmus, oscillopsia, and autonomic involvement.

Specific Qualities

Motor:

Sensory:

Autonomic:

Special senses: +.

Other:

Location of Lesions

Central: The distribution of the cortical vestibular areas is complex [1] and is subject to extensive study. A clearly assigned lesion to a cortical area of vestibular symptoms and signs is clinically difficult, but several paradigms of localization of function have been described [1,2,3].

Brain stem lesion causes include vascular, inflammatory diseases, infections, and tumors.

Intracranial lesions within the skull: Examples include cerebellopontine angle tumors (CPA) and other intracranial tumors.

Exit of the skull: Temporal bone trauma, fractures. Middle ear damage [4], blast injuries.

Other: Other vestibular syndromes include Menier’s disease [5], vestibular neuritis [6], peripheral paroxysmal positional nystagmus [7], positional (central) [8], persistent postural-perceptual dizziness (PPPD) [9], bilateral vestibulopathy (“bilateral vestibular weakness”), vestibular paroyxsmia, and the third mobile window syndromes [10]

Combination with Other CN

In CPA tumors.

Causes and Frequency

Age-related: With increasing age vestibular functions also deteriorate [11]. Presbyastasis is the term coined for aging of sensory systems [12, 13].

Congenital and hereditary: Aplasia; Arnold-Chiari syndrome; atrophy of CN VIII; chromosomal aberrations; Cockayne, Hallgren, and Alström syndrome; hereditary motor and sensory neuropathy (HMSN); Kearns-Sayre; olivopontocerebellar atrophy (OPCA); Refsum’s disease; retinitis pigmentosa; sensorineural deafness; SMA; thyroid disease.

Cupulolithiasis: Benign paroxysmal positional nystagmus. Several subtypes have been described. Positioning maneuvers: Dix, Hallpike, Semont, or Epley.

Immunologic disorders: Demyelinating neuropathies, Hashimoto, leukodystrophies, MS, periarteritis nodosa, sarcoid.

Infection: Labyrinthitis, specific and unspecific.

  • Bacterial: Hemophilus, Lyme disease, petrositis, streptococc pneumoniae, syphilis [14]. Pus reaches the inner ear by either blood or direct invasion (meningoencephalitis).

  • Viral: AIDS, herpes zoster oticus, Ramsey Hunt syndrome, vestibular neuronitis.

  • Mycotic: Coccidiomycosis, cryptococcosis, rickettsial infection.

Metabolic: Diabetes, uremia.

Neoplastic: Acoustic nerve neuroma, metastases, neurofibromatosis [15], schwannoma.

Neuropathy: Several associations (polyneuropathy) [16], also several types of CMT.Perilymphatic fistula: Communication between the middle ear (air-filled) and inner ear (fluid-filled) following trauma or surgery.

Radiation therapy: Usually as late effects [17].

Toxic: Alcohol, aminoglycosides, chemotherapy (cisplatin, cyclophosphamide, hydroxyurea, platinum [18], vinblastine); heavy metals (lead, mercury); quinine, salicylate [19].

Trauma: Blunt, penetrating, or barotrauma. Transverse fractures are often associated with additional CN VII lesion. The less common transverse fractures damage both facial and vestibulocochlear nerves. These fractures involve the otic capsule, passing through the vestibule of the inner ear, tearing the membranous labyrinth, and lacerating both vestibular and cochlear nerves. Vertigo is the most common neurologic sequel to head injury, and it is a positional vertigo.

Vascular: Anterior inferior cerebellar artery aneurysm, arteria posterior communicans aneurysm, labyrinthine hemorrhage or stroke secondary to thrombosis of the labyrinthine (internal auditory) artery, large vascular loops, vascular lesions of the spiral ganglion, vertebrobasilar circulation disorders (history of diabetes, hypertension).

Vasculitis: Immune mediated, Cogan syndrome.

Vestibular epilepsy: [20].

Vestibular paroxysms.

Others: Hyperviscosity syndromes (hypergammaglobulinemia, polycythemia vera, Waldenström’s macroglobulinemia).

Main Investigations

Diagnosis is based on clinical and vestibular testing, laboratory testing (including genetics for hereditary causes), and imaging.

Clinical tests: Romberg, vestibular-ocular reflex test (doll’s head test), video head impulse test [21].

Therapy

Depends on the cause of the vestibular nerve damage.