Neuromuscular Disease Flashcards
what does neuromuscular disease affect?
the peripheral nervous syste,
what specific area of the peripheral nervous system is affected by neuromuscular disease?
lower motor neurones that innervate skeletal muscle
what is the effect of neuromuscular disease on muscle function?
causes a reduction in ability to function properly
where along the neuromuscular pathway can be affected by neuromuscular disease?
anywhere along neuromuscular pathway
how do patients with neuromuscular disease present?
weakness and lethargy
muscles are unable to contract properly
describe what happens at the neuromuscular junction
depolarisation of end of neuron at synapse causes opening of Ca2+ channels
Ca2+ fuses with vesicles containing Ach and these then fuse with the pre-synaptic membrane releasing neurotransmitter into the synaptic cleft
Ach crosses the synapse and binds to Na+ channels causing them to open and the post snaptic cell depolarises
what sort of disease is polyradiculoneuritis?
immune mediated disease
what does polyradiculoneuritis affect?
myelin and/or axons
what is the name for diseases which affect myelin or axons?
axonopathy
what is the most common peripheral neuropathy in dogs?
polyradiculoneuritis
what is the presentation of a patient with polyradiculoneuritis?
short-strided gait that progresses to tetraparesis
ambulatory or non-ambulatory
dysphonia
autonomic function remains
are clinical signs of polyradiculoneuritis the same with all patients?
no, they vary depending on patient and severity
what function remains in polyradiculoneuritis patients?
autonomic (BAR, DUDE is normal)
what is tetraparesis?
all 4 limbs become weak and the patient is unable to walk properly / at all
what is dysphonia?
change in voice (bark)
when does recovery from polyradiculoneuritis occur?
1-4 months after signs stabilise
how is polyradiculoneuritis diagnosed?
accurate patient history
physical and neurological exam
electrodiagnostic testing
muscle and nerve biopsies
what tests are used in electrodiagnostic testing?
EMG - electromylogram
NCV - nerve conduction velocity
how is polyradiculoneuritis treated?
intensive nursing care and physiotherapy
is medical treatment for polyradiculoneuritis effective?
medical treatment with corticosteroids shown to have little to no effect
what is myasthenia gravis a disease of?
neuromuscular transmission which affects the neuromuscular junction
what is the name of diseases which affect the neuromuscular junction?
junctionopathy
what are the 2 ways myasthenia gravis may be aquired?
congenital
aquired
what is congenital myasthenia gravis caused by?
reduced number of Ach receptors
what is acquired myasthenia gravis caused by?
immune mediated
what happens during aquired myasthenia gravis to produce symptoms?
antibodies act on Ach receptor and alter it’s function by preventing or changing the binding of Ach to receptors so there are fewer receptors which are effective and so muscles cannot contract normally
how do myasthenia gravis patients present?
muscle weakness or fatigue which is usually more obvious when the patient is exercising
regurgitation commonly seen
what are the 3 possible types of myasthenia gravis?
focal
generalise
acute fulminating
what type of myasthenia gravis is most severe?
acute fulminating
what is focal myasthenia gravis?
affects one muscle group only
what is generalised myasthenia gravis?
muscles all over the body affected
why is regurgitation commonly seen in myasthenia gravis patients?
due to oesophageal dilation/weakness
what is typical behaviour while walking of a patient with myasthenia gravis?
will walk in a slow/stilted manner for a short period and then need to stop to rest
how is myasthenia gravis diagnosed?
presumptive based on history and presentation
thoracic radiographs to show megaoesophagus
edrophonium / tensilon test
are electrodiagnostics usually used to test for myasthenia gravis?
not usually as they are not specific - will be able to rule out some other diseases but not pinpoint myasthenia gravis
what is a edrophonium / tensilon test?
injection of IVdrug
wait for a few seconds and then walk animal forwards
if + the animals will be able to walk normally where they couldn’t before