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Vestibulocochlear neuritides
Synonym(s): Peripheral vestibular syndrome
Introduction
- Pathological processes in the peripheral receptors in the inner ear and of the vestibular branch of the VIII cranial nerve.
- Cause: includes otitis interna, canine geriatric vestibular disease, aminoglycoside toxicity, topical iodophors or chlorhexidine, hypothyroidism, neoplasia, trauma (especially iatrogenic) and congenital peripheral vestibular disease.
- Signs:
- Head tilt.
- Wide base stance.
- Ataxia with a tendency to lean to one side.
- Circling and nystagmus.
- Deafness and disturbances of balance occur together.
- Important to differentiate these disorders from central vestibular disturbances.
- Diagnosis: signs.
- Treatment: none
- Prognosis: good to guarded.
Presenting signs
- Head tilt.
- Wide base stance.
- Ataxia with tendency to lean to one side Ataxia.
- Circling.
- Nystagmus (horizontal or rotatory).
- Loss of balance/ataxia.
- No weakness.
- Sudden onset.
- Vomiting.
- Concurrent otitis externa and/or otitis media.
- Rolling and falling towards the affected side.
- Concomitant ipsilateral facial nerve paralysis or Horner's syndrome may occur.
- Permanent deafness may result.
Age predisposition
Canine geriatric vestibular syndrome
- Older dogs.
- Puppies up to 3-4 months old - becomes noticeable when puppy begins to ambulate.
Breed/Species predisposition
Congenital peripheral vestibular disease
- English Cocker Spaniel English Cocker Spaniel.
- German Shepherd dog German Shepherd Dog.
- Tibetan Terrier Tibetan Terrier.
- Dobermann Dobermann.
- Japanese Akita Akita.
- Beagle Beagle.
Cost considerations
- Possible myringotomy Myringotomy if fluid or pressure within middle ear.
- Possible bulla osteotomy Bulla osteotomy if otitis interna/media or neoplasia.
- Animal may require diagnostic evaluation, ie CT/MRI scan or brain stem auditory evoked response (BAER Hearing tests ) testing, CSF analysis Cerebrospinal fluid: cytology and prolonged antibiotic therapy.
- Supportive care and anti-emetic drugs if drug toxicity or geriatric vestibular syndrome Vestibular disease: geriatric.
Special risks
- Rupture of the tympanum may result in permanent hearing loss.
- Topical and systemic corticosteroids are contraindicated with otitis.
- Avoid oil based topical drugs if the tympanic membrane is ruptured.
- Trimethoprim sulfur Trimethoprim antibiotic administration may result in keratoconjunctivitis.
Pathogenesis
Etiology
- Autosomal inheritance in congenital peripheral vestibular disease.
- Immune-mediated disease.
- Transitory labyrinthitis.
- Endolymphatic fluid dynamic abnormality within labyrinthine organ.
- Neuritis of the vestibular portion of facial nerve VIII.
- Metabolic, ie hypothyroidism.
- Foreign body related.
- Secondary to nasopharyngeal polyps.
- Extension of opportunistic infection byStaphylococcusspp,Streptococcusspp,P. canis,Clostridium welchiiand especiallyPseudomonas aeruginosa.
- Neoplasia.
- Head trauma (rare).
Geriatric vestibular disease
- Results from abnormal flow of endolymphatic fluid in the semicircular canals of the inner ear secondary to either:
- Disturbance in production, circulation or absorption of the fluid.
- Intoxication of vestibular receptors and inflammation of the vestibular nerve.
Iatrogenic damage during the treatment of middle ear disease
- Trauma from excessive pressure from overzealous irrigation.
- Use of ototoxic compounds in irrigation of middle ear.
Sudden onset idiopathic otitis interna
- Extension of an infection of the external ear through either the tympanic membrane or the oral and nasopharyngeal cavities via the eustachian tubes.
- Hematogenous spread of infectious agent, possibly a virus.
- Hematogenous spread of a systemic infection.
- See under otitis interna Otitis interna , canine geriatric vestibular disease, metronidazole toxicity, aminoglycoside toxicity, neoplasia, trauma (especially iatrogenic) and congenital peripheral vestibular disease.
Predisposing factors
General- Old dogs.
- Dogs which are prone to otitis externa, ie the German Shepherd dog, dogs with pendulous or hairy ears, dogs with generalized skin conditions (especially atopy).
- Hypothyroidism.
- Inhalant anesthesia may change the pressure of the middle ear and predispose to infection.
Specific
- Otitis media.
- Bulla irrigation or bulla osteotomy.
Pathophysiology
- See under otitis interna Otitis interna , canine geriatric vestibular disease, metronidazole toxicity, aminoglycoside toxicity.
- Space occupying lesion → pressure on surrounding nervous tissue → compromised blood supply and anoxia of nervous tissue or direct pressure trauma to nervous tissue → loss of function.
- Autosomal recessive inheritance → non-inflammatory neuroepithelial degeneration of the cochlea with a progressive loss of auditory sensory hair cells → almost complete loss of organ of Corti by 11 weeks of age → bilateral, severe, permanent deafness and vestibular signs which improve as dog learns to compensate.
- Lymphocytic labyrinthitis (otitis interna) → multiple lymphocytic aggregates in the lamina.
- Multiple lymphocytic aggregates in the lamina propria underneath the ciliated columnar epithelium of the inner ear → loss of function, deafness and vestibular signs.
Timecourse
- Usually acute onset - may occur over several hours.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Rossmeisl Jr J H (2010) Vestibular disease in dogs and cats. Vet Clin North Am Small Anim Pract 40 (1), 81-100 PubMed.
- Thomas W B (2000) Vestibular dysfunction. Vet Clin North Am Small Anim Pract 30 (1), 227-249 PubMed.
- Forbes S, Cook J R (1991) Congenital peripheral vestibular disease attributed to lymphocytic labyrinthitis in two related litters of doberman pinscher pups. JAVMA 198 (3), 447-449 PubMed.
- Schunk K L (1990) Diseases of the vestibular system. Prog Vet Neur 1 (3), 247-54 VetMedResource.
- Schunk K L, Averill D R Jr. (1983) Peripheral vestibular syndrome in the dog - a review of 83 cases. JAVMA 182 (12), 1354-1357 PubMed.
- Blauch B, Martin C L (1974) A vestibular syndrome in aged dogs. JAAHA 10 (1), 37-40 VetMedResource.
Other sources of information
- de Lahunta A, Glass E (2009)Vestibular system - special proprioception.Veterinary Neuroanatomy and Clinical Neurology.3rd edn. W B Saunders, Elsevier, St Louis, Missouri. pp 319-347.
- Munana K R (2004)Head tilt and nystagmus.In:BSAVA Manual of Canine and Feline Neurology. S R Platt & Olby N J (eds). pp 155-171.
- Merck Veterinary Manual(1998)8. pp 375-377.
- Cochrane S M (1997)Head tilt (vestibular disease).The 5 minute veterinary consult - canine and feline.pp 74-75.
- Joseph S M (1997)Otitis media and internaThe 5 minute veterinary consult - canine and feline. pp 896-897.
- Cochrane S M (1997)Vestibular disease, geriatric dogs.The 5 minute veterinary consult - canine and feline. pp 1150-1151.
- The Webinar Vet - Understanding Vestibular Syndrome