Diseases of the Spinal Cord Flashcards
Intervertebral disc anatomy.
Intervertebral disc ventrally.
Zygapophyseal joints (articular facets) either side.
Intervertebral disc made up of anulus fibrosis = ligamentous, holding bones together; and nucleus pulposis = cushioning, which should be well hydrated all the time, but can become calcified or fibrous overtime.
- nucleus pulposis is the part of the disc that ‘slips’.
Nerve roots sit within the vertebral canal, are fragile, surrounded by meninges and CSF.
- become a spinal nerve when come out of foramen and ventral and dorsal join together.
– spinal nerves have collagen and protection surrounding them.
- nerve root v painful when squashed.
Normal disc aging.
Fibrous metaplasia occurs:
- dehydration.
- proliferative replacement of nucleus w/ collagen.
- asymptomatic.
Further collagen deposits w/in disc.
Some tearing and healing of anulus.
Proliferative changes of bone around segment.
Enthesiophyte formation (spondylosis).
- normal in ageing and only very rarely causes nerve entrapment.
– NOT AN INDICATOR OF SPINAL DZ.
3 main types of disc disease.
Normal segment subjected to supramaximal force.
- small fragment of hydrated nucleus herniates and contuses cord w/ no compression.
= Non-compressive nucleus pulposis extrusion (traumatic).
- Any, GSD, collie, sighthound.
- peracute.
- non-progressive.
- strong asymmetry.
- only painful initially.
- T3-L3>C1-T2>L4-S2.
Nucleus pulposis undergoes chondroid degeneration (chondrodystrophic breeds).
- calcified nucleus extrudes under everyday pressure and causes compression and contusion.
= Disc extrusion (Hansen type 1) (traumatic).
- any, typically chondrodystrophic e.g. Dachs, Frenchie. >2yo.
- acute.
- non-progressive, but may have repeated episodes.
- typically asymmetrical.
- may be non-painful or v painful.
- T3-L3>C1-T2>L4-S2.
Continued, progressive fibroid degeneration occurs.
- anulus degenerates, tears and hypertrophies causing progressive compression w/ little contusion.
= Disc protrusion (Hansen type 2).
- Any, typically non-chondrodystrophic, large breed; >2yo.
- insidious.
- progressive.
- mild asymmetry.
- usually mild or no pain.
- C1-T2>T3-L3=L4-S2.
Conservative tx of thoracolumbar disc dz.
Rest:
- aim to prevent further material extruding.
- at-risk period seems up to 5w.
- prevent provocative movements that extend back (jumping, running, playing w/ toys or other dogs).
Medication:
- NSAIDs if spinal pain.
- STEROIDS INEFFECTIVE FOR ACUTE SPINAL CORD INJURY!
Time:
- contusion; oedema resolves over 3-6w.
- compression; revascularisation takes place over weeks to months.
Surgical tx of thoracolumbar disc dz.
ACUTE NON-COMPRESSIVE HYDRATE NUCLEUS PULPOSIS EXTRUSIONS DO NOT BENEFIT FROM DECOMPRESSIVE SURGERY!
Determined by location of compression.
- Ventrolateral – mini-hemilaminectomy.
–> small exposure of the side of vertebral canal.
- Lateral or dorsolateral
– hemilaminectomy.
- Ventral – corpectomy.
–> take a bit of vertebral body away.
Decisions to operate or not.
Grade 1 and 2 dogs (pain only or ambulatory paraparetic) are not operated on as recovery and recovery time similar for surgery and for no surgery.
Grade 3 dogs (non-ambulatory and paraparetic) are operated on as recovery better w/ surgery than w/o it, although this is difficult to tell as evidence limited.
Grade 4 dogs (paraplegic) are operated on as massive difference in recovery w/ or w/o surgery.
Grade 5 dogs (pain negative) do tend to need op.
*BASICALLY, CAN WALK, DON’T OPERATE, CAN’T WALK, DO OPERATE.
*OUTCOME NOT SHOWN TO BE CRITICALLY DEPENDENT ON TIME TO SX OR DURATION OF SIGNS. URGENT DZ, NOT EMERGENCY!
Chances of disc extrusion relapse extrusion w/ or w/o sx.
Sx = 7%.
No Sx = 18%.
*based on fenestration sx.
Thoracolumbar disc protrusions.
Much less well described than extrusions.
Non-surgical management suitable for mildly affected cases as may start to resolve in time if main injury traumatic (from ruptured annulus).
Sx indicated for progressive cases.
~80% reported to improve surgically.
Cervical disc extrusions.
Even large extrusions may show pain only; can also be tetra paretic but do not lose pain sensation (would be fatal).
Any breed; small > large, cockers, beagles, always >2yo.
Onset acute.
Progressive; may wax and wane.
Symmetrical.
Usually v painful unless neuro deficits, then may no longer be painful.
- Dx of cervical disc extrusions.
- Tx of cervical disc extrusions.
- PX of cervical disc extrusions.
- CT and myelography can dx.
But MRI best. - Rest may cause resolution of signs.
Sx tx usually ventral slot. - Conservative - 50-80% resolution.
– recurrence common and takes several wks.
Sx - generally excellent, almost all dogs recover completely.
Cervical disc protrusions.
A type of ‘wobbler’.
Degenerative changes:
- flaval ligament hypertrophy.
- dorsal ligament hypertrophy.
- disc prolapse.
