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Neurology

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A rapidly reversible blockage resulting from transient ischemia with no anatomical changes to the nerve
Neuropraxia
Degeneration of axons but the endoneureium and Schwann cells remain intact allowing regeneration of the axon (1mm/day) and return of function
Axonotemesis
Complete severance of a nerve and degeneration of the distal portion and its shcwann cells. Regeneration usually does not occur
Neurotmesis
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
Neurogenic atrophy
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?
6 months
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?
T1
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?
Fibrocartilagionous emboli
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.
Degenerative myelopathy
Diagnostic tests for degenerative myelopathy
Definitive dx is only possible by histopatholgy. Myelin basic protein ELISA, superoxide dismutase genetic testing
Treatment for Degenerative myelopathy
None
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
Ddx for Caudal equina syndrome
Diskospondylitis, neoplasia, lumbosacral osteochondrosis, degenerative myelopathy, cruciate rupture, prostate disease, truama, coxofemoral arthritis, etc
Explosive extrusion of nuclear pulposus material into the spinal canal through the annulus fibrosis
Hansen type 1 displacement
Small tears appear in the anulus fibrosis and there is slow protrusion of the nucleus pulposus. Occurs more commoly in large breed dogs.
Hansen type 2 displacement
Signalment for Thoracolumbar intervertebral disk disease
Dachsunds, poodles, pekingese, beagels; adults 3-7 years of age
Why are there never disc protrusions betwwn T2 and T10? Where do most disc protrusions occur?
intercapital ligament; thoracolumbar area between T11 and L2. About 15% occur in the neck
Grade 1 disc disease
Spinal hyperesthesia without neurological defects
Grade 2 disc disease
paresis but ambulatory
Grade 3 disc disease
pareisis, non ambulatory
Grade 4 disc disease
paralysis with deep pain sensation intact, Surgery recommended
Grade 5 disc disease
paralysis with loss of deep pain, most will not recover regardless of treatment
An infection of the cartilaginous endplate with secondary involvement of the intervertebral disk
Diskospondylitis
Most common agents involved with Diskospondyltitis
S. intermedius, Brucella canis and Streptococcus spp.
Most common sites affected by disksopndylitis
mid thoracic (T4-6), caudal cervical (C6/7) and lumbosacral (L7/S1) vertebrae