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Peripheral nerve: trauma

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Podcast: Peripheral nerve: trauma

Introduction

  • Injury to peripheral nerves is relatively common.
  • Neurapraxia = temporary or partial loss of function.
  • Neurotmesis = permanent loss of function.
  • The effect of loss of sensation and function is variable; for example:
  • Palmar digital neurectomy   Palmar digital nerve: neurectomy  results in loss of sensation to the palmar aspect of the foot, but causes little loss of function.
  • Facial nerve trauma   Facial nerve: trauma    →   distress and secondary signs.
  • Regeneration of peripheral nerves does occur at a rate of about 1 mm/day.
  • Damage to motor nerves easier to assess than damage to sensory nerves.

Cause

  • Direct trauma.

Pathogenesis

  • Traumatic damage   →   rapid denervation atrophy.
  • Extent of pathology will depend on location, type and severity of injury.
  • Injury close to origin of nerve or plexus   →   greater loss of muscular function.
  • Injury to distal or minor branches   →   localized atrophy.

Diagnosis

  • Clinical signs - loss of local motor and/or sensory function.
  • Neurologic assessment .
  • Electromyographic studies .
  • Muscle enzyme studies - to assess potential myopathies.

  • Differential diagnosis
  • Other causes of single muscle atrophy.
  • Equine protozoal myeloencephalitis   CNS: myeloencephalopathy - EHV  .
  • Cauda equina syndrome   Polyneuritis equi  .
  • Fibrotic myopathy   Muscle: myopathy - fibrotic  .

Treatment

See also

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Simeons P et al (1990) Horner's syndrome in the horse - a clinical, experimental and morphologic study. Equine Vet J Suppl 10, 62-65.
  • Cummings J F, Fubini S L & Todhunter R J (1988) Attempts to prevent equine post neurectomy neuroma formation through retrograde transport of two neurotoxins, doxorubicin and ricin. Equine Vet J 20, 451-456.
  • Fordyce P S et al (1987) Use of an ELISA in the differential diagnosis of cauda equina neuritis and other equine neuropathies. Equine Vet J 19, 55-59.

Other sources of information

  • Adair H S & Andrews F M (1995) Diseases of Peripheral Nerves. In: The Horse-Diseases and Clinical Management. Eds: Kobluk C N, Ames T R & Goer R J. W B Saunders Co.