Ch 30 - Medical conditions of the spine Flashcards
List some examples of degenerative spinal diseases
- LWN abiotrophy
- Degenerative myelopathy
What is myelodysplasia?
An anomaly of the spinal cord resulting from incomplete closure or development of the neural tube
List some examples of metabolic spinal disease
- Canine polioencephalomyelopathies
- Globoid cell leukodystrophy
List some nutritional diseases of the spinal cord
- Thiamine deficiency
- Secondary hyperparathyroidism
- Hypervitaminosis A (cat)
Where can a CSF sample be collected?
What is the maximum volume which can be collected?
- Cerebellomedullary cistern
- Lumbar subarachnoid space
- No more than 1ml/5kg
What are the landmarks for entering the cisterna magna?
What structures do you pass through?
- Intersection of a line between the occipital protuberance and the spinous process of C2 and a line between the cranial aspect of the wings of the atlas
- Pass through the skin, atlanto-occipital ligament and the meninges (dura mater and arachnoid)
What volume of CSF is recommened for analysis?
0.75 - 2ml
What is the appropriate interarcuate space for lumbar CSF collection in dogs and cats?
- L5-L6 in dogs
- L6-L7 in cats
Spinal cord has tapered into the conus medullaris
How can you determine if haemorrhage within a CSF sample is iatrogenic?
Centrifugation - clears iatrogenic haemorrhage
What is xanthochromic CSF?
Yellow or straw-tinged CSF suggesting previous subarachnoid haemorrhage (in the absence of hyperbilirubinaemia)
What is used for determining a cell count on CSF?
Fuchs-Rosenthal chamber
What is the ideal timing for performing a cell count on CSF?
What can be done if this timing cannot be achieved?
- Within 30min-1hr of collection
- Refridgeration can help to stabilise the cells
- Can add 1:1 dilution of hetastarch or autologous serum for stabilisation
- If done, a seperate, unaltered alloquat should be provided for protein analysis
What is the normal WBC count of CSF in dogs and cats?
0-5 WBC x 10^6/L (WBC/mcL)
What is the normal CSF protein content in dogs and cats?
- From cerebellomedullary cistern less than 250mg/L (25mg/dL)
- From lumbar cistern less than 450mg/L (45mg/dL)
Increased protein is nonspecific and indicates a damaged BBB or increased local intrathecal IgG production
What are the pros and cons of antigen vs antibody serology?
- Antigen testing may circumvent the problems associated with interpretation of antibody testing
- Antigen testing is insensitivie as it required the presence of the organism in the sample being tested
What is an IgG antibody index?
IgG Index = IgG CSF/ IgG serum
A low index suggests the IgG migrated across the BBB whereas an elevated index indicates theat the source of the IgG is the CNS
What test is highly suggestive of SRMA?
What is the sensitivity and specificity?
Combines elevation of CSF and serum IgA
- sensitivity 91%
- specificity 78%
What is the sensitivty and specificity of PCR for the diagnosis of specific viral meningoencephalitis when the CSF is tested between 48hr and 10 days after onset of signs?
- Sensitivity over 95%
- Specificity over 99%
When combined with serologic testing, chances of diagnosis are maxmimised
List 4 reasons that a negative PCR does not definitively rule out infectious meningoencephalitis
- In individual PCR test may be inherently insensitive
- Nucleic acids may be present in CSF at undetectable levels
- Nuclei acids from organisms may be present within the CNS parenchyma but not in the CSF
- The disorder may have been triggered by a pathogen which is no longer present
Define degenerative myelopathy
What breeds are overrepresented?
What gene is effected?
- Diffuse axonopathy associated with necrosis primarily in the lateral and ventral funiculi of the TL spinal cord segments, accompanied by secondary demyelination and astrogliosis
- GDS, Corgis, Boxer, Rh. Ridgeback
- Missense mutation in the superoxide dismutase (SOD1) gene causing progressive superoxide radical-induced axonal and myelin degeneration within the spinal cord
Define SRMA
What breeds are overrepresented?
- A systemic immune disorder characterised by inflammatory lesions of the leptomeninges and associated arteries that typically respond to corticosteroids
- Beagles, Boxers, Bernese Mt Dogs, Weimeraners, NSDT Retrievers
What vessels can also be effected by SRMA? What other disease is often seen concurrently?
- Vessels of the heart, mediastinum and thyroid glands
- Occassionally concurrent IMPA
What acute phase proteins are elevated in the CSF of dogs with SRMA?
- CRP
- alpha2-macroglobulin
IL-8 has also been indentified in the CSF and correlates with IgA
What are the three forms of GME?
Define GME
- Disseminated
- Focal
- Ocular
An angiocentric, nonsuppurative, mixed lymphoid inflammatory process affecting predominantly the white matter of the cerebrum, caudal brainstem, cervical spinal cord and meninges
List some forms of infectious meningitis
Viral
- Canine distemper (guarded prognosis)
- FIP (fatal)
Protozoal
- Toxoplasma gondii (meningoencephalomyelitis OR myositis-polyradiculoneuritis)
- Neospora caninum
Bacterial
- Staph
- Pasteurella
- E.Coli
- Actinomyces
- etc..
What IgM antibody titres are suggestive of disease of toxo and neo?
Greater than 1:64
Treat with clindamycin
What are three potential sources of bacterial meningitis?
- Haematogenous spread
- Direct inoculation (wounds/needles)
- Direct extension from other structures of the head
Use an ABx which effectively crosses the BBB (metro, enro, chloramphenicol etc) for 1-4 months post resolution
What breeds are overrepresented for discospondylitis?
Great Dane, Labs, Rottweilers, GSD, Doberman, Eng Bulldog
Female GSD overrepresented for fungal disco
What are some speculated caused of vertebral endplate infection in the development of disco?
- “dead-end” capillary loop trapping circulating bacteria
- Microtrauma associated neovascularisation of the adjacent IVD
What are the most common patholgens isolated from disco lesions?
- Staph
- E.Coli
- Brucella canis (zoonotic)
- Strep
- Klebsiella
- Pseudomonas
- Proteus
- Actinomyces
Regarding disco, what is the percentage diagnosis from blood and urine culture as apposed to percutaneous intervertebral disc aspiration?
- Blood and urine culture 40%
- Disc aspiration 60%
What is a good empiric option for treating discospondylitis?
- First-generation cephalosporins or amoxiclav
- Good penetration of bone!
- 17% of staph spp are resistant to first-gen cephalosporins….
- Treat for 8 weeks
What are some hypotheses for the entry of the fibrocartilaginous into the vessel in FCE?
- Direct penetration of the fibrocartilage from the nucleus pulposus disc into the vessel
- Remnant vessel within the nucleus pulposus
- Herniation of a portion of the nucleus pulposus into the bone marrow and subsequent retrograde movement into the internal vertebral venous plexus
- Neovascularisation of the degenerated intervertebral disc
How can MRI imaging help to prognosticate in FCE lesions?
- Leison-to-vertebral length ratios greater than 2, 60% unsuccessful outcome
- Lesion-to-vertebral length ratio less than 2, 100% successful outcome
What are some speculated caused of vertebral endplate infection in the development of disco?
- “dead-end” capillary loop trapping circulating bacteria
- Microtrauma associated neovascularisation of the adjacent IVD
