Equis ISSN 2398-2977

Temporohyoid joint: osteoarthropathy

Contributor(s): Graham Munroe, Vetstream Ltd

Introduction

  • Cause: infection usually bacterial (hematogenous)   →   osteitis.
  • Signs: head shaking/tossing, ear rubbing; acute onset vestibular signs and facial nerve paralysis; sudden death.
  • Diagnosis: physical examination, ear examination, gait evaluation, radiography, endoscopy, CSF analysis.
  • Treatment: antibacterials, anti-inflammatories, surgical resection of stylohyoid bone segment.
  • Prognosis: guarded.

Pathogenesis

Etiology

Pathophysiology

  • Infection of middle or internal ear   →   osteitis   Bone: osteitis - septic  of the tympanic bulla, proximal stylohyoid bone and the temporohyoid joint at articulation with the petrous temporal bone.
  • Arthritic changes   →   pain   →   headshaking and head-tossing.
  • Arthritis   →   movement of joint   →   bony proliferation   →   fusion of stylohyoid bone to petrous temporal bone.
  • Loss of joint movement   →   stress on thin-walled petrous temporal bone   →   fracture   →   internal acoustic meatus (contains vestibulocochlear, and facial nerve)   →   neurologic signs.
  • Aging   →   osteoarthritis of the temporohyoid joint (may be preceded by otitis media).
  • Otitis media:
    • Low-grade infection   →   moves ventrally   →   osteitis of tympanic bulla   →   osteitis of the stylohyoid bone and temporohyoid articulation with the petrous temporal bone at base of skull.
  • Osteitis:
  • Osteoarthritis:
    • Exostosis   →   loss of normal temporohyoid articulation.
    • Enlargement of the stylohyoid bone   →   fusion with the petrous temporal bone   →   cessation of signs of pain.
    • Narrowing of the auditory meatus   →   obscures tympanic membrane.
  • Fusion of joint   →   loss of flexibility during eating, vocalization and riding   →   excessive stress on the stylohyoid bone and petrous temporal bone   →   fracture.
  • Petrous temporal bone fracture:
    • Trauma to inner ear, vestibulochochlear and facial nerves   Facial nerve: trauma    →   secondary conditions, eg corneal ulceration.
    • Trauma to cranium   Head: fractures    →   inflammation + extension of infection   →   encephalitis   →   seizures   →   death.
  • Stylohyoid fracture   →   large callus formation and eventual petrous temporal fracture.

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.
  • Bras J J, Davis E & Beard W L (2014)Bilateral ceratohyoidectomy for the resolution of clinical signs associated with temporohyoid osteoarthropathy.Equine Vet Educ26(3), 116-120VetMedResource.
  • Koch C & Witte T (2014)Temporohyoid osteoarthropathy in the horse.Equine Vet Educ26(3), 121-125VetMedResource.
  • Palus Vet al(2012)Retrospective study of neurological signs and management of seven English horses with temporohyoid osteoarthropathy.Equine Vet Educ24(8), 415-422VetMedResource.
  • Grenager N Set al(2010)Epidemiological features and association with crib-biting in horses with neurological disease associated with temporohyoid osteoarthropathy.Equine Vet Educ22(9), 467-472VetMedResource.
  • Frame E Met al(2005)Scintigraphic findings in a case of temporohyoid osteoarthropathy in a horse.Equine Vet J17(1), 11-13VetMedResource.
  • Blythe L L (1997)Otitis media and interna and temporohyoid osteoarthropathy.Vet Clin North Am Equine Pract13, 21-42PubMed.

Other sources of information

  • Clement S (1987)Peripheral neuropathies.In:Current Therapy in Equine Medicine.Ed: N E Robinson. W B Saunders, Philadelphia. ISBN: 0 7216 1491 4.


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