Neurology -Week 2 Flashcards
Sensory tract deficit leads to ___
Motor tract deficit leads to ____
Sensory = Ataxia Motor = paresis
Where in spinal cord are the sensory nuclei
Sensory nuceli are dorsal & lateral funiculi
Where in spinal cord are the motor nuclei
UMN = Lateral ventral funiculi
LMN: Ventral horse grey matter.
Why do UMN synapse with LMN?
UMN synapse on LMN in ventral horn grey matter.
UMN facilitates and inhibits flexor/ extensors
Define Paresis
Decreased voluntary movement
C.F. Plegaia- absence of voluntary movement
L4-S3 lesion would present as
Normal forelimb LMN signs (decrease tone/ reflexes)
T3-L3 lesion would present as
UMN signs-Increased tone/reflexes
Forelimb; NORMAL
Differentiate L4-S3 lesion from T3-L3 if reflex is normal therefore UMN intact = T3-L3
C1-C5 myopathy presentation
Forelimb: UMN signs
Hindlimb:
UMN signs
If all four limbs have LMN signs it is likely to be
2 lesions or more likely neuromuscular localisation
Forelimb: LMN signs
Hindlimb: UMN signs are likely caused by a lesion
Lesions C6-T2
Forelimb and Hindlimb UMN signs are likely caused by
C1-C5 myopathy
OR
Brainstem (BUT DIFFERENTIATED ON MENTATION)
How is the severity of myopathies assessed i.e. what is lost first?
First is Priorioception, then movement then nociception. (first superficial pain then deep pain)
How to assess Nociception
Conscious perception of pain.
Limb withdrawel does not equal pain (see face)
Example of a disease that causes C6-T2 myopathy
Cervical spondylomyelopathy Forelimb: LMN
Hindlimb: UMN
Hypervitaminosis A causes what kind of myopathy
IN CATS.
C1-C5 and C6-T2 myopathy.
Forelimb: Normal
Hindlimb: LMN signs
Appropriate reflex’ to test would be
Suspect L4 to S3 myopathy therefore test
- Patella - Femoral n - L4-L6
- Sciatic - Withdrawel- L6-S7
- Puadendal: s1-s3 - anal sphincter
Example of a degenerative disease that causes L4-S3 MYOPATHY
Lumbosacral stenosis.
Forelimb: Normal
Hindlimb: LMN signs.
Signalment for Lumbosacral stensosis
Older large breed dogs (GSDs) Bladder dysfunction (affects Pudendal nerve S1-S3)
Difference between Hansen Type 1 disk degeneration and Type II disk degneration
Type I: Chondrodystrophic breeds. Dauchunds. Nucleus fibrosis mineralise and extrudes
Type II; larger dogs. More acute as protrusion of annulus fibrosis
Type II Hansen disk degeneration leads to _____ of the articular facets
Type II disk degen leads to subluxation of the articular facets which leads to a step which is an unstable join.
Leads to thickening/in-folding of the interarcuate ligament and epidural fibrosis,.
= LUMBOSACRAL STENOSIS
Can lead to Spondylosis
Treatment of Lumbosacral stenosis
- Conservative: Restrict exercise for 6-8 weeks. Anti inflamm and pain relief.
- Dorsal laminectomy surgery
Complications of Dorsal laminectomy
Treatment for Lumbosacral stenosis (or conservative!)
IMMEDIATE= seroma
DELAYED= Discospondylitis (decrease blood supply)
or lamina formation/ fibrosis.
If severe LMN deficits are present/ chronic urinary incontinence = emergency and less fav prog.
Polyneuritis Equi clinical signs
Tail paresis (easily missed) Dilated anus Faecal retention Perineal loss of sensation Muscle atrophy if chronic
Ddx for Polyneuritis Equi
Trauma- sacral fracture - common
EHV1= myeloencephalopathy = highly infectious / fatal
Primary or secondary cystitis
Pathogenesis of Polyneuritis Equi
How to diagnose
Immune mediated damage to peripheral nerves of caudal equine.
May follow adenovirus (??)
Diagnosis: Tail head muscle biopsy- Lymphocytic infiltrate seen around intramuscular nerves
Treatment of Polyneuritis Equi
Usually supportive.
Immunosuppressives are not usually effective.
Prog: ok for life, poor for return to function
Drugs to relax bladder
Phenoybenzamine (blocks sympathetic receptors)
Typical history of neuromuscular disease
LMN in fore and hind = tetraparesis. think neuromuscular (or 2 lesions)
Weakness, difficulty rising, exervise intolerance, regurgitation, lameness and pain.
Altered voice
Altered respiratory effort or inspiratory stridor
if paresis without ataxia likely to be ___
Muscular in origin.
Neuromuscular disease is tetraparesis +- proprioceptive ataxia
What changes to the pupil, tear production and HR would you expect with neuromuscular disease
- Dilated pupil
- Decreased tear production
- Bradycardia
Gait for neuromuscular disease
Paresis +- ataxia Frequent sitting down Exercise intolerance Low head carriage Chopping and stilted gait (hypometria)
Normal EMG is
EMG: Electromyogram,
Normally Silent
EMG Fibrillation potentials
Caused by denervation and inflammation. Biphastic.
Sounds like rain on a tin roof.
Sponataneous action potentials of single myofibres
Positive sharp waves sound
Like a racing car driving by,
Dull thud or chug.
Caused by denervation.
EMG sounding like a machine gun would be indicitive of
Complex repetitive discharges.
Many myofibres in near synchrony.
How to calculate mean nerve conduction velocity
MNCV = Distance in mm / (prox latency - distance latency)
An action potential is a sudden increase in the permeability of
Action potential= sodium channels open = increase permeability.
How does Botulism cause tetraplegia?
Clinical signs vary from mild paresis to tetraplegia. LMN signs.
Found in soil. Equine botulism only toxin B found.
Toxin blocks the release of acetylcholine at NMJ IRREVERSIBLY
3 clinical form,s of bolulism
1) ingested toxin (all ages) - outbreaks. Only reported form in UK
2) Toxico-infectious - young foals. Spores ingested- organism prolifs in intestine
3) wound botulism (very rare)
In the UK botulism has only been reported in horses with access to ____
Big bale silage or haylage. C
aused by soil contaimination/ animal or bird carcasses.
pH <5.3 inhibits spores
Diagnosis of Botulism in horses
Reduced tongue tone - remove tongue from mouth, will not retract. and history of exposure to silage.
Treatment of Botulism in horse
Antiserum containing antibody to toxin B (only found in UK) C and D.
Broad spec antibiotics for pneumonia NOT PROCAINE AND AMINOGLYCO.
Fluid therapy.
Prog is GUARDED.
What is Tensilon testing
AKA Edrophonium,
Tests for Myasthesia gravis.
Inhibits acetylcholinesterase therefore prolongs present of neurotransmitter acetylcholine - increase muscle strength,.
NOT SPECIFIC for MG.
Diagnosis of Myasthesia gravis
- Tensilon testing (Edrophonium cholride)
2. Check for paraneoplastic (thymoma!)
Treatment of IM MG
> 3MNTS, gsd, labradors, golden retrievers
Pyridostygmine (start low and increase dose)
Immunemodulatory drugs
3 forms of Immune mediated MG
- Focal MG (megaoes with regurgi)
- Generalised MG, exercise intoler with megaoeso
- Fulimating form
Signalment for Congenital MG
6-8 weeks old.
jack russel terrir, springer spaniel, miniature dachshund.
Decrease of AChR.
Treatment: Pyridostygmine
Difference between Immune mediated and Congenital MG
IM: Autoantibodys against receptors
Congenital: Decrease of ACh receptors. 6-8 weeks
Examples of Peripheral neuropathies in a) calves b) cows/horses
a) calves: femoral nerve paresis post parturition
b) Cows/Horses: Obturator nerve
What is Sweeny
Suprascapular nerve damage with muscle atrophy of supra and infraspinatus
Well muscled labrador, collapse 30 mins post exervise then short rest = mobile again. Likely Diagn=
Exerise intolerence.
Gene identified in labradors.
Treatment: exercise restriction.
Clinical signs of Myopathic syndrome
Paresis. Exercise intolerence. Still, stilted gait.
Muscle atrophy or hypertrophy. Muscle pain on palpatation.
Muscle tone in ipsilateral/contralateral limb for vestibular disease
Ipsilateral limb: decrease tone
Contralateral limb: exaggerated extensor tone.
Gait in myopathic syndrome
Stiff, stilted gait.
How does pacing in horses differ from pacing in dogs?
Pacing in horses= sign of ataxia = normal for some horses
Pacing in small animal = weakness (paresis)
How does the organisation of white and grey matter differ in the brain and spinal cord?
Brain: Grey matter (cell bodies) OUTSIDE white matter
Spinal Cord: Grey matter INSIDE white matter
Retractor oculi reflex=
Test for horse.
Press on cornea through eyelid, feel for retraction of the globe.
Afferent: Trigeminal
Efferent: Abducens (innervations retractor bulbi muscle)
Stringhalt is the result of contraction of which muscles?
youtube HINDLIMBS Uncontrollable exaggerated movement of the digital extensor muscle OR when the digital flexor muscles lack sufficient opposition,
Cause of Stringhalt
Toxicity - flat weed (false dandilion) = Hypochaeris radicata
Lesions of the scaitic nerve
Diagnosis of Stringhalt
More exaggerated when turning or backing up.
Can be diagnosed with EMG (Electromyleogram)
Treatment of Stringhalt
Surgical resection of a part of the tendon running along the hock
Or if caused by false dandilion remove from pasture
Pathogenesis of Stringhalt
This faulty wiring of the spindles causes certain muscles to contract either too early or too late, or too much or too little, during certain phases of the gait. Leading to spasticity of the Biceps femoris muscle
Why can a C6-T2 lesion cause Stringhalt signs?
C6-T2 lesion: Forelimb: LMN Hindlimb: UMN signs
Springhalt = Hindlimb, faulty spindles therefore of extensor muscle.
Equine neuro exam, what else could be causing the weakness?
Non-neurological reason for weakness? Locomotor assessment. Jaundice in horse than seems depressed? Foot abscess?? Mentation: bright or depressed? Head pressing?
Horse head turning during neuro exam would be suggestive of
forebrain.
How common are Cerebellum neuropathies in horses?
Rare, Intention tremor, ataxia without weakness. Spastic/ exagerrated movements.
Weakness and Ataxia in horse would be suggestive of
Brainstem disease (includes pons and medulla) Ascending proprioceptive pathways and descending motor pathway. Also contains cranial nerve nuclei therefore good cranial nerve exam can find position of lesion
Ataxia clues in horses
Pacing
Circumduction`
Lameness vs Ataxia
Lameness: normally regularly irregulat
Ataxia: Irregularly irregular
Inflammation of a ligament is known as
Desmitis e.g. Bilateral pelvic limb suspensory ligament desmitis is a common cause of unusal ataxia-like deficit. = sacroiliac disease
What can you assume about spinal reflex’ in standing horse
Standing horse assume spinal reflexes are intact. Withdrawal reflexes are still useful.
8YO Gelding, pelvic limb lameness which doesn’t respond to NSAIds, Worse when head is lifted up. Imported from USA.. Ataxic front legs
Cerebellar disease v. unlikely in the horse.
Worse when lifting head = C1-C5.
Tail pull on right = weakness. Lateralising. No pain. Chronic.
Gluteal muscle atrophy = LMN. Ventral root (MOTOR)
Can’t explain with one lesion = Equine protozoal myeloencephalitis.
Tail pull while walking tests =
UMN
Tail pull while standing =
LMN
Horse tests positive for Equine protozoal myeloencephalitis- what is pathogenesis?
Affects grey and white matter.
No horse to horse transmission so no need to quarantine
Faecal contam from birds.
Treatment of EPM
Equine Protozoal Myeloencephalitis. Affects sensory and motor.
Treamtment: Inhibitors of folate metabolism - sulfadazine
Coccidiostats (Ponazuril)
NSAIDs
Steroids (only if deteriorating)
Guarded prog (esp as LMN signs - muscle atrophy)
Sarcocystis neurona
= Protozoa causes Equine protozoal myeloencephalitis
Main DDx of EDM is ___
Main differential for Equine Degenerative myeloencephalitis is Cervical Veterbral malformation/ stenosis
2 types of Cervical Vertebral Stenosis
Static: Significant spinal cord compression on neutral (normal) radiograph (and flexed)
Dynamic: Instability only, seen on radiograph when next is flexed (NOT WHEN NEUTRAL)
Wobblers syndrome =
Cervical vertebral stenosis. Most commonly C3-C6. 4 -23 months.
Diet too high in energy/ calcium
Also seen in dogs but normally C6-T2
Type of radiograph to diagnose ‘wobblers’
CVS can be diagnosed with lateral cervical radiographs.
Most commonly affects C3 - C6.
Equine Degenerative Myopathy pathogenesis
Affects white matter. Caused by vit E deficiency in the diet. (continually stabled horses)
Birth to 2 years old. Most are 6-12 months.
Spastic paraparesis + pelvic limb ataxia
Most common cause of facial nerve paralysis in dogs
Otitis media
What does a) sigamore b) false dandelion cause in horses
a) Sigamore- autumn- atypical myopathy
b) false dandelion (hypochaeris radicata) - Stringholt
Difference between Stringholt and Fibrotic myopathy
Stringholt: hypermetric gate due to hypocharesis radicata- false dandilion
Fibrotic myopathy: slapping down of foot (norm semimembranous, semitendinous or gracalis) due to muscle tear, IM injection or neuropathy.
Vit E deficiency causes_______
Nutritional myopathy in horses
Why is Gabapentin a useful add on for epilepsy in dogs?
Renally excreted so avoids hepatotox
Ddx for hypoglycaemia induced seizure
INSULINOMA
Toxicology (esp Xilitol)
Hypoadrenocorticism
Recurrent Exertional Rhabdomyolsis
Exertional Rhabdomyolysis can be acquired (eccentric contraction, oxidative injury, metabolic exhaustion) or inherited (defective calcium reg e.g. RER!) OR polysaccharidge storage myopathy
Prevention of recurrent exertional rhabdomyolysis
RER: Inherited (defective calcium reg OR polysacch storage myo)
for defective Ca regulation:
Oral Dantrolene (calcium release channel blocker)
and HIGH FAT/LOW CARB diet
Reg exercise/ turn out
PSSM1
–>Mutation in glycogen synthase gene in skeletal muscle.
PSSM/EPSM are heritable. High prevalence in some draft breeds
Presentation and Treatment of Supraspinatus/Infraspinatus contracture
Abduction extension
Tx: tenotomy
Myosites ossificans
Secondary to trauma
Which types of horses get fibrotic myopathy? and which type of dogs
a) Fibrotic myopathy: Quarterhorses- semitendinous/semimembranous
b) dog: GSD/Doberman/Rottweilers = gracilis
Fibrotic myopathy gait
INT/EXT/INT ROTATION. STIFLE/HOCK/FOOT
Pathogenesis of Lumbosacral stenosis
CHECK BLADDER FUNCTION: pudendal s1-s3
1. Hansen type II disk degen (AF) / protrusion
2. Subluxation of articular facets
3. Thickening of interarcutae ligaments = epidural fibrosis
Can lead to spondylosis/instability
Why might you consider radiograph for horse with suspected polyneuritis equi?
Main Ddx: Sacral fracture (common)
also EHV-1 (csf tap)
or cystitis
Syringomyelia pathogenesis
Associted with Chiari like malformation.
Syrinx formation is associated with obstruction of CSF flow at the foramen magnum.
Intermittent yelping due to neck pain, phantom scratching of neck.
Arachnoid diverticulum congenitally predisposes
