Neuromuscular Disease Flashcards
What are the two potential causes for neuromuscular junction disease?
A failure of the NMJ to release sufficient ACh, or a failure of the muscle to respond to this ACh
What is the consequence of failure to release or respond to ACh in neuromuscular junction disease?
Reduced/absent muscle contraction
What are some ways to recognise muscle weakness caused by neuromuscular junction disease?
It is usually bilateral, and gets worse with repeated use
What is the motor end plate?
The synapses formed between motor neurones and muscles
What is curare? This is toxic if given how?
A plant like compound which occupies the same position as the ACh receptor but it does not open ion channels so there is no muscle contraction / IV or IM
What is Botulism? Who is it often seen in?
An organism present in soil causing food and wounds to become infected / IVDU
What are the two main pre-synaptic NMJ diseases?
Botulism and Lambert-Eaton syndrome
What is the clinical presentation of Botulism?
Rapid onset weakness without sensory loss
What is the pathophysiology behind Lambert-Eaton syndrome?
There are antibodies to pre-synaptic Ca++ channels which leads to less vesicle (containing ACh) release
Lambert-Eaton syndrome is often a paraneoplastic syndrome. It has a strong association with what?
Small cell lung cancer
How will patients with Lambert-Eaton syndrome present?
Proximal weakness, affecting the lower and then upper limbs
How is Lambert-Eaton syndrome treated?
3,4-diaminopyridine
What autoantibodies are seen in myasthenia gravis?
Postsynaptic ACh receptors
What is the only postsynaptic NMJ disorder?
Myasthenia gravis
Describe the two peak incidences of myasthenia gravis?
Young females in the 3rd decade of life, or males in the 6th/7th decades of life
What happens to the incidence of antibody positive myasthenia gravis?
It increases with age and is more common in males