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 Pract30(6), 322-329 VetMedResource.
  • Sargent S J, Frank L A, Buchanan B R, Donnell R L & Morandi F (2006)Otoscopic, cytological and microbiological examination of the equine external ear canal.Vet Dermatol17(3), 175-181 PubMed.
  • MacKay R J (2004)Brain injury after head trauma: pathophysiology, diagnosis, and treatment.Vet Clin North Am Equine Pract20(1), 199-216 PubMed.
  • Pease A P, van Biervliet J, Dykes N L, Divers TJ & Ducharme N G  (2004)Complication of partial stylohyoidectomy for treatment of temporohyoid osteoarthropathy and an alternative surgical technique in three casesEquine Vet J36(6), 546-550 PubMed.
  • Walker A M Sellon D C, Cornelisse C J, Hines M T, Ragle C A, Cohen N & Schoot H C 2nd (2002)Temporohyoid osteoarthropathy in 33 horses (1993-2000).J Vet Intern Med16(6), 697-703 PubMed.
  • Bedenice D, Hoffman A M, Parrott B & McDonnel J (2001)Vestibular signs associated with suspected lightning strike in two horses.Vet Rec149(17), 519-522 PubMed.
  • Tabamo R E & Donahue J E (1999)Eastern equine encephalitis: case report and literature review.Med Health R I82(1), 23-26 PubMed.
  • Paradis M R (1998)Tumors of the central nervous system.Vet Clin North Am Equine Pract14(3), 543-561, vii PubMed
  • Blythe L L (1997)Otitis media/interna and temporohyoid osteoarthropathy.Vet Clin North Am13(1), 21-42 PubMed.
  • Tietje S, Becker M & Bockenhoff G (1996)Computed tomographic evaluation of head diseases in the horse: 15 cases.Equine Vet J28(2), 92 PubMed.
  • Mayhew I G & Washbourne J R (1990)A method of assessing auditory and brainstem function in horses.Br Vet J146(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, Missouri. 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, Missouri. pp 941-945. ISBN: 0 8151 1743 4.


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