Bovis ISSN 2398-2993

Femoral paralysis

Contributor(s): Dick Sibley , Paul Wood

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Introduction

  • The femoral nerve originates from L5 region of the spine and innervates the quadriceps muscle mass which extends the stifle joint.
  • The nerve is anterior to the wing of the ilium and is generally protected from direct trauma during calving.
  • Paralysis can occur when the nerve is damaged through direct trauma or stretching, particularly when the limb is overextended caudally.
  • Damage may be temporary or permanent, but paralysis of the powerful quadriceps muscles causes severe dysfunction to locomotion, as the animal is unable to use the affected limb as the stifle collapses without any power of extension.

Pathogenesis

Etiology

  • The femoral nerve leaves the spinal column at L5, and passes caudo-ventrally to the the quadriceps.
  • The nerve also innervates the sartorius muscle which adducts the limb and provides some flexion to the hip.
  • A saphenous branch provides sensory function to the medial thigh.
  • When the limb is overextended backwards at the hip, the nerve can become stretched and torn.
  • Such overextension can occur as a primary injury or secondarily to other problems. For example:
    • As a complication to milk fever Milk fever or post parturient recumbency Down cow where the cow tries to rise and the back legs are extended backwards, particularly on slippery surfaces
    • When the foot or lower limb becomes trapped and the animal struggles to release the entrapment.
    • When a cow in estrus Estrus: signs and detection or is bullied is ridden by another and crushed to the ground causing damage to the lumbar spine and extension of the back legs.
    • When a calf is presented backwards and traction is applied to the hind legs to relieve the dystocia Dystocia  Calving aids: correct use.
  • Occasionally, the nerve can be damaged during parturition, if pressure from an oversized fetus causes ischemia in the nerve. However, such pressure is more likely to affect the obturator nerve Obturator paralysis than the femoral.
  • Once the nerve is damaged, motor function is impaired or lost and the muscles become paralysed.

Predisposing factors

General

  • Involuntary overextension of one or both hind limbs predisposes to femoral paralysis.

Specific

  • Dystocia with excessive or prolonged traction to the hind limbs.
  • Pressure from hematomas, abscesses or other lesions in the region of the femoral nerve.
  • Prolonged extension of the hind leg due to being trapped.
  • Hyperextension of the hind limb or limbs as a result of slipping, struggling to rise or being ridden and crushed on slippery surfaces.

Pathophysiology

  • Tearing of the nerve at its root will lead to total loss of function and poor chances of recovery.
  • Tearing of the peripheral branches of the nerve will lead to a more localized paralysis, where the innervated muscles can adapt to function in place of those paralyzed.
  • If the loss of nerve function is due to pressure and / or ischemia there is a reasonable chance that function will return.

Timecourse

  • The effects of femoral nerve paralysis are seen immediately after the trauma that injures the nerve.
  • If the injury is progressive (such as caused by swelling of tissues surrounding the nerve causing ischemic damage) then the condition may seem to be progressive over hours or days.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Poulton P J (2013) Cattle Practice 21, 174-180.
  • Huxley J (2006) In Practice 28, 176-184.

Other sources of information

  • Lameness in Cattle. 2nd Edition. A D Weaver (ed) (1981), Wright Scientechnica.


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