Bovis ISSN 2398-2993

Suprascapular paralysis

Contributor(s): Nick Bell, Sophie Mahendran , Roger Blowey

Introduction

  • Cause: trauma to the cranial aspect of the shoulder.
  • Signs: prominent scapular spine due to atrophy of the supraspinatus and infraspinatus muscles, and lateral deviation of shoulder joint while weightbearing.
  • Diagnosis: clinical signs and neurological examination.
  • Treatment: rest and NSAIDs.
  • Prognosis: good to guarded depending on extent of damage.

Pathogenesis

Etiology

  • Mild neuropraxia during weightbearing is a common injury in cattle; complete paralysis is less common.
  • Trauma to front of shoulder such as charging into a yoke during the loading of a trim chute, hitting a vertical stanchion at speed, from leaning against a crush yoke with head outstretched for long periods during foot trimming.
  • Fractures of neck of scapula or scapular tuberosity.
  • Extremes of movement, especially caudal extension of shoulder.
  • Once damage initiated (even if slight) further shoulder movement, especially sudden outward excursions, may perpetuate the damage to the nerve.
  • Can also be caused by injections of irritant material into the caudal neck, resulting in inflammation in the nerve.

Pathophysiology

  • Suprascapular nerve originates from the C6 and C7 spinal segments:
    • It innervates the shoulder extensors (supraspinatus muscle) and the forelimb abductors (infraspinatus muscle).
  • The nerve passes across the cranial edge of scapula and is prone to stretching/bruising.
  • Damage to nerve may be mild leading to neuropraxia (temporary impairment of function); or severe   leading to  neurotmesis (possibly permanent).
  • Denervation atrophy of supraspinatus and infraspinatus   →   loss of lateral shoulder support   →   sudden lateral outward motion of shoulder during weightbearing and   →   prominent scapular spine.
  • Often several other nerves in the brachial plexus appear to be involved.

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.
  • Hartnack A K (2017) Spinal cord and peripheral nerve abnormalities of the ruminant. Vet Clin North Am Food Anim Pract 33 (1), 101-110 PubMed.
  • Constable P (2004) Clinical examination of the ruminant nervous system. Vet Clin North Am Food Anim Pract 20 (2), 185-214 PubMed.
  • Divers T J (2004) Acquired pinal cord and peripheral nerve disease. Vet Clin North Am Food Anim Pract 20 (2), 231-242 PubMed.

Other sources of information

  • de Lahunta A & Divers T J ( 2008) Neurologic Diseases. In: Rebhun’s Diseases of Dairy Cattle. Thomas J Divers and Simon F Peek (eds), 2nd edn. Chapter 12, pp 504-560. Saint Louis: W.B. Saunders. doi:https://doi.org/10.1016/B978-141603137-6.50015-6.


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