Equis ISSN 2398-2977

Sciatic nerve: paralysis

Contributor(s): Caroline Hahn, Ruth Morgan, Vetstream Ltd

Introduction

  • Peripheral nerve injuries are relatively common; some regeneration of peripheral nerves occurs but is slow.
  • See also peripheral nerve injuries overview   Peripheral nerve: trauma  .
  • Cause: direct trauma, inflammatory disease of the spinal cord, bacterial infection, osteomyelitis fractures or from misdirected injections in foals.
  • Signs: extension of stifle and hock and loss of sensation in distal limb, dragging of the foot.
  • Diagnosis: clinical signs and examination of muscles.
  • Treatment: steroids and non-steroidal anti-inflammatories may be useful.
  • Prognosis: depends upon extent of damage to nerve.

Pathogenesis

Etiology

  • Direct trauma.
  • Associated with coxo-femoral luxation or acetabular fractures.
  • Associated with pelvic fractures or sacral/pelvic osteomyelitis.
  • Inflammation of the spinal cord, eg equine protozoal myelitis.
  • In adults the nerve is very deep, but in foals it is more superficial and so can be damaged by intramuscular injection.

Pathophysiology

  • The sicatic nerve originates from segments L6-S1.
  • It innervates the semimembranosis and semitendinosis muscles before splitting into tibial and peroneal branches.
  • Sciatic nerve damage   →   loss of tibial and peroneal nerve function   →   loss of sensation in distal limb (below stifle).
  • The tibial branch is more commonly affected.
  • Motor loss   →   poor limb flexion.
  • Damage may be mild and temporary (neuropraxia).
  • Severe/permanent loss of function may occur (neurotmesis).

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.
  • von Schweinitz D G (2014)Electroacupuncture for nerve injury in the horse.Equine Vet Educe26, 24-26 VetMedResource.
  • Hahn C (2008)Common peripheral nerve disorders in the horse.In Pract30(6), 322-329 VetMedResource.


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