A rapidly reversible blockage resulting from transient ischemia with no anatomical changes to the nerve
Degeneration of axons but the endoneureium and Schwann cells remain intact allowing regeneration of the axon (1mm/day) and return of function
Complete severance of a nerve and degeneration of the distal portion and its shcwann cells. Regeneration usually does not occur
Peripheral nerve injuries can result in:
Neuropraxia, axonotemesis, neurotmesis
Anesthesia and absence of peripheral reflexes in areas supplied by the affected nerve; marked and rapid muscle atrophy are signs of what condiiton?
Peripheral nerve damage
refers to muscle fibers that undergo progressive atrophy due to loss of their connections to the lower motor neurons of the CNS
What medication can be used to treat peripheral nerve injury?
glucocorticoids to decrease inflammation
What surgical procedures are indicated w/peripheral nerve injury?
If possible, decompress nerve surgically. May try transplantation of tendons of flexor muscles along w/arthrodeisis
After how long of not regaining function should amputation be considered for peripheral nerve damage?
Occurs due to trauma that abducts the front limb and forces it caudally or cranially
Brachial plexus avulsion
Denervation of extensors and flexors of the elbow and carpus carpus indicate injury where?
Nerve roots C8 and T1
Denervation of shoulder extensors and flexors indicate injury where?
C6 and C7
Loss of panniculus response in association with brachial plexus avulsion is indicative of injury to which nerve?
Lateral thoracic nerve at C8 and T1
Horner's sydndrome is a result of injury to which ventral nerve roots?
What is the prognosis of a brachial plexus avulsion? What is the best predictor of complete recovery?
Gaurded to poor; presence of pain
How is brachial plexus avulsion treated?
Protect the limb and wait and see if regeneration occurs. If none after 6 months, amputate. Physiotherapy will help prevent contracture of joints.
Where do malignant peripheral never sheaht tumors most often occur?
In the caudal cervical area where they are associated w/the brachial plexus
A history of slowly progressive monoparesis w/root signs is very suggestive of what condion?
Malignant peripheral nerve sheath tumor
How are MPNSTs treated?
Surgical resection, but often results in further loss of function and there is a high rate of recurrence. Radiation and chemo have limited benefit.
Signalment for fibroartilagionous emboli
50% Large breeds (Irish wolf hounds esp) and 20% small breeds (mini schnauzers) 1-7 yrs old
Non-progressive paresis or paralysis that is lateralizing and non-painful, occurring peracutely after exercising w/no hx of trauma is indicative of what condition?
How should fibrocartilaginous embolism be treated?
Dex or methylprednisolone succinate to reduce edema and inflammation + supportive care and cage rest. Physio/hydrothearpy instituted immediately after dx seems to have large influence on recovery rate.
Prognosis for FCE?
Many dogs do not improve. Px worse for dogs w/LMN vs UMN signs. Recovered animals may have residual deficits.
Occurs due to degereration of axons and their myelin sheaths in the thoracolumbar spinal cord.
Diagnostic tests for degenerative myelopathy
Definitive dx is only possible by histopatholgy. Myelin basic protein ELISA, superoxide dismutase genetic testing
Treatment for Degenerative myelopathy
Signalment of Lumbosacral instability
5-8 yold large breed (esp GSD and border collies), very rarely in cats
Dogs with what are about 8% more likely to develop cauda equina syndrome?
Lumbosacral transitional vertebra
Treatment of cauda equina syndrome
Best results w/lumboacarl dorsal laminectomy and removal of the ligaments and bone putting pressure on the nerves