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
Describe L-2-hydroxyglutaric aciduria
- Inherited disease of staffies
- progressive mental retardation, seizures, tremor or stiffness at exercise (worse at exercise rather than after)
- DNA testing and breeding program to eradicate
What is ischaemia?
Restriction in blood supply to a tissue, may be a consequence of a thrombus, embolus, or due to other conditions
What is fibrocartilaginous embolisation?
True stroke of the spinal cord
Describe the gross appearance of the spinal cord following fibrocartilaginous embolisation
- Discolouration of spinal cord in central region
- Plus of fibrocartilage blocking artery in spinal cord
Explain how lateralised ischaemia of the spinal cord occurs
- Ascending artery in spinal cord splits and supplies blood to middle region of spinal cord
- Embolism will block one of these branches leading to lateralised ischaemia
Describe the clinical signs of fibrocartilaginous embolism
- Sudden onset
- Non-painful
- Non-progressive paralysis
- History of running, sudden yelp and paralysis
Describe the prognosis and treatment of fibrocartilaginous embolism
- Prognosis depends on location but usually good
- No specific treatment, only supportive
Outline the diagnostic findings for a fibrocartilaginous embolism
- Clinical signs
- T2 MRI: focal area o hyperintensity showing ischaemia, no compressive lesion
- Myelography: NAD, or mild focal swelling
What are the 2 potential causes of a stroke?
- Thrombo-embolic disease i.e. cutting off blood supply to region
- Haemorrhagic disease i.e. bleeding within that region
Describe the clinical signs of focal ischaemic encephalopathy in the dog
- Idiopathic paralysis with unilateral facial paralysis
- Unilateral vestibular disease
What is meant by “doggy stroke”?
Idiopathic vestibular disease
What is Menieres disease?
Dilation of fluid in chambers ofinner ear leading to vestibular syndrome (Doggy stroke)
Compare stroke in dogs and humans
- In dogs, idiopathic vestibular disease looks like stroke
- True stroke of rare
Outline the diagnosis of vestibular syndrome in dogs
- Need o identify if central or peripheral based on clinical signs
- Normally based on advanced imaging
Describe what is meant by old dog vestibular disease
- More severe form of idiopathic vestibular disease
- Head tilt, unable to stand, roll if put on floor until hits the wall
- May require extended periods for recovery, can recovering 2-3 weeks
What is ischaemic myelopathy and what is it also known as?
- Thromboembolic disease affecting the descending aorta/iliac vessels
- Aka: saddle thrombus, aortic thromboembolism, iliac thrombosis
What is the consequence of ischaemic myelopathy?
Whole spinal cord becomes ischaemic, making whole back end of animal ischaemic and may sometimes affect one front leg
Describe the clinical signs of ischaemic myelopathy
- Pulseless, cold back legs
- Pallor
- Pain
- No proprioception
- Acute onset hindlimb weakness/paralysis
Compare the prevalence and underlying causes of ischaemic myelopathy in dogs and cats
- Very common in cat, may be secondary to cardiomyopathy
- Very rare in dog, may be secondary to kidney failure and Cushing’s
Outline the diagnostic findings of ischaemic myelopathy
- Clinical signs and examination
- Ultrasound aorta
- Cardiac evaluation (esp. in cat)
- MRI: diffuse changes through soft tissue caudal to lesion, thrombus visible within aorta
Describe the treatment and prognosis of ischaemic myelopathy
- Mainly treatment of underlying disease from prevention
- Treatment of underlying cause sometimes allows return from ischaemia in back legs
- Prognosis guarded depending on underlying cause and ability to identify this
In which species does post-anaesthetic ischaemic encephalopathy mainly occur?
Cats
When might ischaemic encephalopathy occur in all species?
Post seizure
Which procedure carries an increased risk of cerebral ischaemia in cats?
Dental procedure with the use of a mouth gag
Describe ischaemic encephalopathy in cats
- Primary disease process of unknown aetiology in cats occurring spontaneously
- True stroke affecting one cerebral cortex, most commonly post anaesthetic
Describe the clinical signs of post-anaesthetic ischaemic encephalopathy in cats
Episodes of hypoxia resulting in transient blindness or more severe clinical signs
Describe the treatment for post anaesthetic ischaemic encephalopathy
- Time
- Supportive therapy to facilitate return of vision
What should be done following identification of a case of post-anaesthetic ischaemic encephalopathy?
Assess anaesthetic regime and monitoring as it is likely that there will have been reductions in blood pressure during anaesthetsia
Describe the MRI appearance and prognosis for post seizure encephalopathy
- MRI findings of focal regions of oedema within brain postictally
- Spontaneous resolution in most cases with conservative therapy
What is the prognosis for post anaesthetic blindness in cats?
Usually good for return of vision with supportive therapy
describe post-anaesthetic myelopathy in horses
- Uncommon complication of apparently uneventful GA
- Do not get up following anaesthetic
- Difficult to prevent as reason unknown
Outline the importance of angiostrongylus in vascular causes of neruological disease
- Should be a differential as can cause bleeding of nervous system
- Clinical signs are sudden onset and progressive, location affects whether see myelopathic or encephalopathic signs or both
Compare the prevalence of FCE in dogs and cats
Common in dogs, rare in cats
Evaluate the use of MRI and findings in intervertebral disc disease
- Concussive: focal T2 hyperintensity
- Compressive: demonstrable compression of spinal cord and intraparenchymal changes
- Is the ideal imaging modality for IVDD
Describe the pathophysiology of spinal fracture leading to neurological signs
Concussion, compression or laceration of spinal cord parenchyma
Describe the clinical signs of spinal fracture
- Sudden onset spinal cord dysfunction
- Often painful
- Instability
- +/- other traumatic injuries
Evaluate the use of radiography for the diagnosis of spinal fracture
Fracture will be visible if orthogonal views taken properly
Evaluate the use of myelography in the diagnosis of spinal fractures
Ongoing compression demonstrable if present, integrity of dural sac demonstrated
Evaluate the use of CT in the diagnosis of spinal fractures
Ongoing compression visible and fracture outlined
Evaluate the use of MRI in the diagnosis of spinal fractures
Demonstrable compression of spinal cord if present and intraparenchymal changes including integrity of spinal cord
What imaging modalities are best for diagnosis of spinal fractures?
Radiography, CT, myelography, MRI i.e. any
What are the treatment options for spinal fracture?
Fixation, decompression, time (i.e. leave) or euthanasia as indicated
Presentation: LH absent voluntary movement, absent withdrawal, absent myotatic reflexes, deep pain present. No spinal pain. Panniculus reflex intact. FL and RHL normal, cranial nerve examinations NAD
Describe and explain the lesion localisation
- Flaccid paralysis therefore LMN
- Lumbosacral plexus or left side of spinal cord in Lumbar region
- Plexus rather than individual nerve affected
- Lumbosacral plexus comes out of spinal cord at L4-S3
Describe the clinical neurological signs of Neospora caninum in the dog
- Puppy, comes from the dam
- Can take up to 6mo before showing signs
- Progressive hindlimb stiffness with no movement in hindlimb muscles
- Pain over muscles and none on spine
How is Neospora caninum diagnosed in dogs?
- Serology
- Muscle biopsy
What is the treatment for Neospora caninum?
Clindamycin
List the differentials and how these are diagnosed (in order) for a cat presented with rapidly progressive paraparesis developing over 48hrs, non-ambulatory paraparesis, general, cranial nerve and FL examination all NAD. HL non-ambulatory, increased tone, resentment of spinal palpation. Withdrawal reflexes and pain sensation present, absent tail movement
- FIP: CSF, MRI
- Neoplasia (FeLV in particular, but also extra-axial tumour affecting spine): MRI to identify where FNA to be taken from
- Spinal trauma: radiography
- Ischaemic myelopathy/aortic thromboembolism: exclude due to presence of pulses
- IVDD: MRI
- GME, toxoplasma and FCE possible but very rare
Identify some of the simple pain scales that are available
- Simple descriptive scale
- Numerical rating scale
- Visual analogue scale
- Dynamic interactive visual analogue scale
What do multidimensional pain scales assess?
Intensity of pain, sensory and affective qualities of pain
Can can pain be measured experimentally?
- Mechanical thumb (repeatable stimulus to measure analgesia)
- Thermal device to see at what temperature animal responds
- Von Fref filaments
Give examples of validated pain scales in dogs and cats
- Glasgow pain tool (dogs)
- Short form Glasgow Pain Scale
- Cats: Botucatu, Glasgow CMPS
- Colorado Pain Scale (good for cats, not validated)
Describe the typical presentation of Myasthena Gravis
- Runs normal, progressively weaker, then needs to rest before can run again
- Labradors predisposed
Compare the pathogenesis of congenital and acquired myasthenia gravis
- Acquired: autoantibodies to Ach receptor
- Congential: deficiency of receptors
What are the methods for diagnosis of myasthenia gravis?
- Serology to detect antibodies
- Administration of edrophonium and assessing effect
- Electrophysiological (not widely available)
- History
Describe the use of edrophonium in the diagnosis of myasthenia gravis
- Anticholinesterase
- Increases Ach in neuromuscular junction
- In normal animal will cause a crisis, so needs to be short lasting so only have to keep animal alive for short periods if it is not MG
- Very expensive
Describe the typical appearance of labrador retriever myopathy
- Aka floppy labrador disease
- Stiff gait and marked muscle atrophy in puppies of both sexes
- Signs worsen with cold, stress, exercise
- Progessive exercise intolerance as puppies
- May be unable to keep heads elevated in normal position from 3mo
- Tendon reflexes absent
- Signs stabilise by 6-9mo
Describe the pathogenesis and prognosis of labrador retriever myopathy
- Path: atrophy of type II muscle fibres
- Good prognosis, signs stabilise by 6-8mo
Describe the most common cause of exercise induced weakness in working labradors (cause, history, management)
- Likely glucose relaed
- Usually responds to phenobarbitone
- Usually well-muscled, good working life, suddenly exercise introlerant
- Work out how much can do then only exercise up to that level
Outline the treatment of myasthenia gravis
- Pyridostigmine bromide
- Low dose pred (contraindicated in first opinion) and azathioprine
- Upright feeding
- For acquired: long acting anti-cholinesterase, immunosuppressive doses of steroids
Outline the prognosis for myasthenia gravis
- Variable
- Significant number improve dramatically 3-6mo down the line and go into spontaneous remission, care with anticholinesterases that they do not go into cholinergic crisis
