Ch 33 - Degenerative Lumbosacral stenosis Flashcards
What kind of joint is the LS joint?
Amphiarthrosis (cartilaginous joint)
What are the embryological origins of the vertebral column and the spinal cord?
How does this contribute to the formation of the cauda equina?
Spinal cord is neuroectodermal origin, vertebral column is mesodermal origin.
They grow at different rates with the vertebral column outgrowing the spinal cord. As a result, the nerve roots of the terminal portion of the spinal cord have to course a longer distance to exit their respective intervertebral foramina
Where does the spinal cord terminate in various sized dogs?
- Large/giant breeds - L4
- Dogs under 15kg - L6
- Toy breeds and cats - L7
Dural sac extends 1-2cm further caudally than the terminal conus medullaris and may extend into the sacrum in over 80% of dogs
Define cauda equine syndrome
clinical signs resulting from a disease process which involves the LS articulation and effects the nerve roots and/or spinal nerves of the cauda equina
What percentage of LS disc cultures are positive?
23%
What proinflammatory cytokines and growth factors are released with compressive radiculopathy?
- TNFalpha
- IL-6
- IL-beta
Perpetuates the disease locally and within neural tissue and is an important mechanism in the induction of neuropathic pain
What is intermittent claudication?
Paroxysmal manifestations consistant with caudal lumbar pain or pelvic limb cramping, or weakness as a result of vascular compromise or compression of nerve roots in the cauda equina. Signs are exacerbated by activity
What nerves are effected by degenerative LS stenosis?
What reflex is most reliable?
- Cranial tibial
- Gastrocnemium
- Perineal reflex and flexor-withdrawal reflex may be normal or depressed
Often, deficitis relate to sciatic dysfunction, causing a failure of hock flexion on withdrawal reflex.
May also be a pseudohyperreflexia of the patellar reflex due to loss of antigonistic muscle tone from the caudal muscle musculature
What is the only means of providing functional data about the cauda equina?
Electrophysiologic testing
What are the most consistent radiographic signs suggestive of LS stenosis?
- Sacral osteochondrosis
- Transitional vertebrae
- LS step formation
- LS disc vacuum phenomenon
What are the main CT findings consistent with LS stenosis?
- Loss of epidural fat
- Abnormal soft tissue density in intervertebral foramina
- Buldging of LS disc
- Displacement of dural sac
- Subluxation and osteophytosis of zygapophyseal joints
- Compressed and inflammed tissue will often contrast enhance
MRI findings are similar with the high signal fat getting replaced by hypointense material (disc vs fibrosis vs bony proliferation)
What is the success rate of medical management?
55%
79% improvement with 1mg/kg methypred epidural. 3 injections (1st injection, 2 weeks and 6 weeks later)
What are the indications for surgical stabilisation?
- Moderate to severe neurological signs
- Pain
- Ventral subluxation of S1
- To prevent further development of instability
How is the S1 nerve root identified?
Large spinal ganglion at the level if the LS IVD
What are the 2 approach options for a foraminotomy?
What can be used to enhance visualisation?
- Dorsally through a dorsal laminectomy
- Laterally without a laminectomy
Can use endoscopy to improve visualisation.
A osteotomy of the wing of the ilium has been described
