Equis ISSN 2398-2977

Neurology: vestibular disease

Contributor(s): Linda Lou Blythe, Graham Munroe

Introduction

  • Cause: damage to the vestibular system which is responsible for maintenance of the normal orientation of the trunk, limbs and eyes with respect to the position and movements of the head.
  • Signs: disturbed equilibrium and ataxia, without paresis.
  • Diagnosis: history and clinical signs (exacerbated by blindfolding).
  • Treatment: appropriate treatment of the primary cause of the vestibular damage.
  • Prognosis: guarded - affected animals often centrally accommodate with time and can return to their previous function, although signs can still be elucidated by blindfolding.

Pathogenesis

Etiology

Specific

Pathophysiology

  • The vestibular system maintains balance, and orientation of the trunk, limbs and eyes with respect to the position and movements of the head.
  • The vestibular system comprises a receptor organ within the inner ear (within the petrous temporal bone) and the vestibulocochlear nerve (VIIIth cranial nerve).
  • The facial nerve (VIIth cranial nerve) is closely associated with the vestibulocochelar nerve and the petrous temporal bone, and they enter the internal auditory meatus together.
  • Vestibular disease usually results in disturbed equilibrium and ataxia, without paresis.
  • Disorders are usually unilateral.
  • Extension of the suppurative process in otitis media   Ear: otitis externa / otitis media  into the adjacent facial canal and internal auditory meatus or temporohyoid joint disease    Temporohyoid joint: osteoarthropathy  may   →    sudden fracture of the petrous bone    →   acute signs of vestibular and facial nerve dysfunction.
  • Extension of the infection through the internal acoustic meatus can   →    focal suppurative meningitis, fever and depression; complicating the signs and worsening the prognosis.
  • Idiopathic vestibular syndrome may be the result of transient disease of the vestibular nerve, eg viral or immune-mediated neuritis or labyrinthitis.

Timecourse

  • Central and visual accommodation often occurs with time, and the horse can return to its former use, although signs of vestibular disease can still be stimulated by blindfolding (Rombergs test).
  • Idiopathic vestibular syndrome: can be very acute in onset and full recovery occurs in 2-3 weeks without treatment. 
  • Tremorgenic mycotoxocosis: full recovery occurs a few days to several weeks following early removal of the affected fodder.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hahn C (2008) Common peripheral nerve disorders in the horse. In Pract 30 (6), 322-329 VetMedResource.
  • Sargent S J, Frank L A, Buchanan B R et al (2006) Otoscopic, cytological and microbiological examination of the equine external ear canalVet Dermatol 17 (3), 175-181 PubMed.
  • MacKay R J (2004) Brain injury after head trauma: pathophysiology, diagnosis, and treatmentVet Clin North Am Equine Pract 20 (1), 199-216 PubMed.
  • Pease A P, van Biervliet J, Dykes N L et al (2004) Complication of partial stylohyoidectomy for treatment of temporohyoid osteoarthropathy and an alternative surgical technique in three casesEquine Vet J 36 (6), 546-550 PubMed.
  • Walker A M, Sellon D C, Cornelisse C J et al (2002) Temporohyoid osteoarthropathy in 33 horses (1993-2000)J Vet Intern Med 16 (6), 697-703 PubMed.
  • Bedenice D, Hoffman A M, Parrott B & McDonnel J (2001) Vestibular signs associated with suspected lightning strike in two horsesVet Rec 149 (17), 519-522 PubMed.
  • Tabamo R E & Donahue J E (1999) Eastern equine encephalitis: case report and literature reviewMed Health R I 82 (1), 23-26 PubMed.
  • Paradis M R (1998) Tumors of the central nervous systemVet Clin North Am Equine Pract 14 (3), 543-561 PubMed
  • Blythe L L (1997) Otitis media/interna and temporohyoid osteoarthropathyVet Clin North Am 13 (1), 21-42 PubMed.
  • Tietje S, Becker M & Bockenhoff G (1996) Computed tomographic evaluation of head diseases in the horse: 15 casesEquine Vet J 28 (2), 92 PubMed.
  • Mayhew I G & Washbourne J R (1990) A method of assessing auditory and brainstem function in horsesBr Vet J 146 (6), 509-518 PubMed.

Other sources of information

  • Rush B R (2004) Vestibular Disease. In: Equine Internal Medicine. Eds: Reed S M, Bayly W M & Sellon D C. Elsevier, USA. pp 579-588. ISBN: 0 7216 9777 1.
  • Hahn C H, Mayhew I G & Mackay R J (1999) Diseases of Vestibular and Cerebellar Structures. In: Equine Medicine & Surgery. Eds: Colahan P T, Mayhew I G, Merritt A M & Moore J N. Mosby Inc, USA. pp 941-945. ISBN: 0 8151 1743 4.


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