equis - Articles
Femoral nerve: trauma
Introduction
- Cause: external trauma to the limb.
- Signs:
- Cannot support weight.
- Lack of joint extension.
- Decreased stride length.
- Buckling of limb on weightbearing.
- Flexion of stifle with automatic flexion of fetlock and hock.
- Atrophy of quadriceps muscle.
- Absence of patella reflex.
- Loss of sensation to medial leg (mid-thigh to hock).
- Bilateral injury.
- Diagnosis: pelvic limb lameness.
- Treatment: DMSO, corticosteroids, surgery.
- Prognosis: good to fair.
Presenting signs
- Buckling on weightbearing on the affected limb.
- Inability to support weight.
- At a walk, the limb is advanced with difficulty with a decreased stride length.
- Resting with all joints of the rear limb flexed.
- Absence of the patellar reflex.
- Bilateral femoral nerve injury will result in an animal that cannot bear weight and may dog-sit.
- Hypalgesia of the medial aspect of the rear limb from the mid-thigh to the hock.
Geographic incidence
- Worldwide.
Age predisposition
- Femoral and/or sciatic nerve neurapraxia sometimes occurs in new-born foals after assisted deliveries → force applied as hips delivered, either anterior or posterior presentations.
Pathogenesis
Etiology
- Damage to the femoral nerve can occur from an external blow to the limb or postanesthetic recumbency.
- Bilateral femoral nerve injury has been reported in horses after general anesthesia and from sacroiliac luxation after dystocia in mares.
Pathophysiology
- The quadriceps femoris group of muscles is innervated by the femoral nerve.
- Inability to extend the stifle results from its paralysis.
- As a consequence of stifle flexion, the tarsus and digit are flexed and the horse is unbale to bear weight on the limb.
- The hock can still be flexed to pull the limb forward, but the patellar reflex is depressed or absent.
- Hypalgesia of the medial thigh.
Timecourse
- Atrophy of the quadriceps muscles (biceps femoris, vastus lateralis) may be seen within 1 to 2 weeks of the injury.
Diagnosis
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Treatment
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Prevention
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Outcomes
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Hahn C (2008) Common peripheral nerve disorders in the horse. In Pract 30 (6), 322-329 VetMedResource.
- Dyson S, Taylor P & Whitwell K (1988) Femoral nerve paralysis after general anesthesia. Equine Vet 20 (5), 376-380 PubMed.