42. Diseases of the neuromuscular junction. Toxicosis, tetanus, botulism Flashcards
included in neuromuscular junction
axon terminal
synaptic cleft
endplate
general clinical signs of diseases of neuromuscular junction
autonomic signs
decreased muscle tone
decreased segmental spinal reflexes
cranial nerve deficits
tetraplegia
weakness
Presynaptic disorders
less ACh is released from the terminal
LMN type deficits
Clinical signs of Presynaptic disorders
Hypotonia
hyporeflexia
dysphagia
dysphonia
Post synaptic disorders
Problems related to Ach specifically
exercise induced weakness
Name of Postsynaptic disorder
myasthenia gravis
Acquired myasthenia gravis
Autoantibodies produced against ACh receptors on post synaptic terminal
decreased number of functional receptors
Congenital myasthenia gravis
ACh receptor deficiency/ abnormality on the post synaptic membrane of the NMJ
Forms of myasthenia gravis
Generalised
Focal
Fulminant
Generalised myasthenia gravis
normal at rest
exercise induced weakness
paresis
megaoesophagus
ptyalism
Focal myasthenia gravis
weakness of an isolated muscle group
fulminant myasthenia gravis
progressive symptoms
tetraparesis
diffuse weakness
Diagnosis of myasthenia gravis
Tensilon test
ACh-Rez Ab - determines the autoantibodies
Electrodiagnosis
Treatment of myasthenia gravis
Acetylcholinesterase inhibitors - pyridostigmine
immunosuppression
Enzymatic disorders
Acetylcholinesterase inhibitors
Vegetative overstimulation
Clinical signs of Enzymatic disorders
Exercise intolerance
muscle tremor
stiff gait
exercise induced collapse of labradors
similar symptoms to myasthenia gravis
after prolonged activity –> overheat –> fatigue –> flaccid paresis
Toxicosis affect NMJ
Organophosphate & carbamate
Strychinine poisoning
ivermectin toxicosis
lead toxicosis
Organophosphate & carbamate
found in insecticides
inactivation of acetylcholinesterase
Organophosphate & carbamate
clinical signs
salivation
lacrimation
bradycardia
Organophosphate & carbamate
treatment
atropine
pralidoxime
Strychinine poisoning
glycine antagonist
Strychinine poisoning
clinical signs
drawn together ears
saw horse position
hypersensitivity
opisthotonos
seizure
apnoea
ivermectin toxicosis
GABA agonists
collies
ivermectin toxicosis
clinical signs
salivation
mydriasis
vomiting
tremors
bradycardia
ataxia
seizures
ivermectin toxicosis
treatment
symptomatic
lead toxicosis
clinical signs
- Lethargy
- GI symptoms
- Inappetence
- Depression
- Weight loss
-Seizures - Haematologic alterations
- Ataxia
- Blindness
- Anorexia
- Myoclonus
- Hysteria
lead toxicosis
diagnosis
measurement of Pb in blood, urine, liver and kidney
lead toxicosis
treatment
removal of lead product
Ca-EDTA IV
anticonvulsant
diuretics
GCC
other toxicosis
metaldehyde toxicosis
pyethrins
ethylene glycol
Tetanus
pathomechanism
cl. tetani enters wound –> anaerobic environment –> neurotoxin production
Tetanus neurotoxin causes
inhibits glycine & GABA release –> spasm
forms of Tetanus
focal
generalised
Clinical signs of Tetanus
extensor rigidity
rictus grin
dysphagia
resp muscle spasm
dyspnoea
salivation
increased muscles tone
muscle spasm
tachypnoea
Treatment of Tetanus
wound debridement
tetanus antitoxin
AB
muscle relaxant - acp, diazepam
Botulism
cause
Cl. botulinum
uncooked mead, rotten carcass, spoiled feed
Botulism
pathomechanism
toxin irreversibly cleaves the protein that docks ACh to the presynaptic membrane –> decreases Ach
Clinical signs of Botulism
Acute paresis
facial paralysis
tachycardia
bradcardia
urinary retention
megaoesophagus
flaccid paralysis
dysphonia
ileus
mydriasis
dry eye
dysphagia
death
Diagnosis of Botulism
toxin detection
Treatment of Botulism
Emetic - apomorphine
Supportive care
not AB
Antitioxin
Good prognosis
