Neurological diseases of small animals Flashcards
Neurodegenerative, vascular, pain
Name the different groups of neurodegenerative diseases
- Age related conditions
- Predetermined conditions
- Spontaneous degenerations
What is spondylosis?
Descriptive term for the production of new bone, very common in older animals
Discuss the diagnostic significance of identifying spondylosis on radiographs
- Usually incidental
- Can cause problems if exxtensive, or imponging on neural structures
- May indicate that other problems are present e.g. unstable intervertebral disc disease or a migrating foreign body
- Significant if as a result of migrating foreign body, but this looks very different from normal ventral spondylosis
What is meant by ventral and bridging spondylosis and compare
- Ventral: formation of new bone on ventral aspect or vertebrae
- Bridging: formation of bone over vertebral foraminae
- Bridging may lead to trapped nerves and be clinically significant
What is discospondylitis?
Infectious inflammation within the intervertebral disc (essentially abscesses within disc)
Describe the clinical presentation of discospondylitis
- Chronic, progressive condition
- Pain, localisable to site
- Variable paresis, rarely paralysis
- Abscesses almost always present with local pain +/- pyrexia and are rapidly progressive
What methods are required in the diagnosis of discospondylitis?
- Radiography
- Advanced imaging
- Culture of blood/urine
Describe the appearance of discospondylitis on radiography
- Desctructive changes in vertebral body
- Loss of definition of vertebral body end plates
- Radiographic changes may take ~2 weeks to become visible
Describe the use of urine/blood culture in the diagnosis of discospondylitis
Bacteria (or fungi) get into disc via blood supply, so should find bacteraemia
Compare the radiographic appearance of discospondylitis and neoplasia
- Neoplasia would not lead to loss of definition of adjacent end plates the same as discospondylitis does
- If 2 end plates are affected then must be discospondylitis, if only one affected (but similar “fluffy” appearance, then neoplastic
Describe the treatment for discospondylitis
- 6 weeks appropriate antibiotic based on urine/blood culture
- FNA from intervertebral space can also be used for culture
- Use broad spec antibiotic
Describe the monitoring of a case of discospondylitis that is being treated with antibiotics
- Clinical signs and radiography
- Radiography lags behind clinical picture, so main monitoring is clinical signs
- If non-painful in 6 weeks then this indicates infection is cleared
Describe the 2 components of the intervertebral disc
- Annulus fibrosus around the outside, made up of fibrocartilage
- Nucleus pulposus in the middle, made up of collagenous protein, non-collagenous protein, proteoglycan and glycoproteins
Describe the pathophysiological changes that lead to the intervertebral disc disease in dogs
- Progressive cahnges with age within nucleus pulposus, leading to dehydration of the nucleus
- Leads to changes in physical properties of the disc, becomes hard rather than jelly leading to disc failure
Compare the pathophysiology of intervertebral disc failure in chrondrodystrophic breeds to other breeds
- I chondrodsytrophic, pathological changes start from 1 year of age and differ in nature
- May get calcification of disc in chondrodystrophic
- More prone to Hansen type I (extrusion) disc failure
Explain the difference between intervertebral disc extrusion and protrusion
- Extrusion: stamp on doughnut, rapid acute explosion of nucleus pulposus out leading to acute compression of the spinal cord
- Protrusion: slower bulging of disc, mainly dorsal annulus bulging upwards compressing spinal cord
What is the prevalence of disc extrusion at the following portions of the spinal cord?
a: C2-T2
b: T2-T10
c: T11-L3
d: L5-S1
a: 15%
b: rare
c: 80%
d: <2%
Where is the most common area for disc extrusion and why?
T13-L1, fixed ribcage joins flexible lumbar spine, stress in this region
In non-chondrodystrophic breeds, lumbosacral region is most common
Describe the clinical picture of a disc protrusion
- Slow compression of spinal cord, chronic
- Paresis/paralysis
- Rate and degree determined by severity of compression
- Proprioception usually fails first
Describe the clinical picture of a disc extrusion
- Bruising and oedema in spinal cord if happens quickly
- May have bruising alone or compression may still be present
- Pain +/-paresis or paralysis if impinging on spinal cord
What methods are used in the diagnosis of intervertebral disc disease?
- Clinical picture
- Radiography
- Advanced imaging (myelography, CT, MRI)
Evaluate the use of radiography in the diagnosis of intervertebral disc disease
- May see changes in disc e.g. calcification of nucleus
- Narrowing of intervertebral foraminae
- Will not show where the spinal cord is compressed, will indicate where there may be changes
- Narrowing of disc space
- Vacuum phenomenon
Evauate the use of myelography in the diagnosis of intervertebral disc disease
- Can see sub-arachnoid space attenuation due to compression if present
- Can be suspicious of compression of spinal cord but cannot tell what is causing the compression, may also be a tumour
- NAD in concussive, or mild focal swelling
Describe what may be seen on CT with intervertebral disc disease
- Narrowed disc space, vacuum phenomenn, calcification, usually non-specific
- With comressive may see calcified material in canal
Compare progressive vs stable intervertebral disc disease
- Progressive: disc continues to bulge/extrude out and put pressure on spinal cord
- Stable: initial insult to spinal cord, once extruded just stays there and remains stable
Compare compressive vs concussive intervertebral disc disease acute spinal cord pathology
- Concussive: bruising to spinal cord, result of small amount of disc coming out
- Compressive: large extrusion compressing the cord
- In most cases have both
Compare the treatment of compression and concussive intervertebral disc disease
- Compressive: relieve compression
- Concussive: leave, cannot do anything for bruising
- Steroids should not be used for either, contraindicated in dogs
List the key aspects of conservative therapy for intervertebral disc disease
- Cage rest
- Bladder management
- Good nursing
- Physiotherapy
- Analgesia
- May need to continue for 4 weeks, should see improvement in 2 weeks
Explain the importance of cage rest in the treatment of intervertebral disc disease
Minimise disc movement and allow annulus fibrosus to scar over, preventing rest of nucleus pulposus coming out
Explain the importance of bladder management in the treatment of intervertebral disc disease
- Most important part of management
- If cannot move back legs, then bladder also not functioning
- Deep pain sensation in back legs but no movement, probably have significant pain in bladder
- Catheterise
What is chronic degenerative radiculomyelopathy (CDRM)/degenerative myelopathy (DM)?
Progessive degenerative pathology affecting the spinal cord, starting in the thoracolumbar region then progressing cranially to affect the cervical spine
Describe the signalment for CDRM/DM
- Commo in GSD
- 6-9yr old
Describe the clinical picture of CDRM/DM
- Progressive hindlimb ataxia
- Become non-ambulatory
- Eventually affects forelimbs
- 9 month progression to PTS
Describe the diagnosis of CDRM/DM
- Diagnosis by exclusion: if alive after 12 months, not CDRM
- genetic testing available but is not diagnostic, lots of false positive
- Advanced imaging not that helpful either
Describe the treatment of CDRM
- No effective treatment available
- Some palliation with physiotherapy
What is an important differential for CDRM and explain the significance
- Protrusive IVDD
- Difficult to differentiate on advanced imaging
- Surgery would worsen CDRM, but would improve IVDD
What is canine cognitive function disorder?
Excessive loss of tissue assocaited with altered behaviour e.g. loss of house training, confusion
Describe the clinical appearance of cognitive function disorder
- MRI shows brain too small
- Aggressive behavioural change
- Differentiation of normal vs abnormal degeneration difficult
- Degeneration of CCD much earlier
Outline the treatment options for canine cognitive function disorder
- Dietary alterations: some improvement, most clinical trials anecdotal, some respond, some do not
- Drug therapy with selegiline
- Treatment combined with behavioural therapy
Describe lysosomal storage disorders
- Diverse group of inherited disorders of metabolism
- Lead to enzyme deficiencies within specific intracellular metabolic pathways
- result in accumulation of abnormal metabolites which eventually become toxic
- Worse if occur in cells that cannot replicate e.g. neurones
- Rare