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)