Myasthenia Flashcards
This toxin cleaves presynaptic proteins involved in vesicle formation and block vesicle docking with the presynaptic membrane
Botulinum toxin
This condition results from antibodies to presynaptic calcium channels
LAMBERT EATON Myasthenia gravis syndrome
In LAMBERT EATON myasthenia gravis syndrome, why are antibodies to presynaptic calcium channels bad?
This prevents vesicle release
Which calcium channels are affected in LAMBERT EATON myasthenia gravis syndrome?
Presynaptic
LAMBERT EATON Myasthenia gravis syndrome has a strong association with which type of cancer?
Underlying small cell carcinoma
Name 2 PRE-synaptic disorders
- botulism
- lambert eaton myasthenia gravis syndrome
Name a POST-synaptic disorder
Myasthenia gravis
Most common disorder of neuromuscular junction
Myasthenia gravis
In myasthenia gravis, the antibodies are targeted against which receptors?
Acetyl choline receptors (AChR)
Reduced numbers of functioning receptors leads to what _____
Muscle weakness and fatiguability
myasthenia gravis
In myasthenia gravis, symptoms start when ACh receptors reduced to __% of normal
30% of normal
Flattening of endplate folds?
Myasthenia gravis
Apart from blocking the binding of ACh, what do the antibodies in myasthenia gravis do?
Trigger inflammatory cascades that damage the folds of the postsynaptic membrane
Which other gland-y thing plays a role in myasthenia gravis?
The thymus - 75% of patients have hyperplasia or thymoma
When are the two peaks of incidence in myasthenia gravis?
Females in the third decade
Males in 6th/7th decade
(female:male ratio - 3:2)
What is the most common presentation of myasthenia gravis?
Extraoccular weakness, facial and bulbar weakness
If limbs become weak in myasthenia gravis, are distal or proximal usually affected?
Proximal
Treatment for myasthenia gravis?
Pyridostigmine (acetylcholinesterase inhibitor)
Thymemctomy
Steroids/aziathioprine (immune modulating)
Emergency treatment - plasma exchange/immunoglobulin
Emergency treatment for myasthenia gravis?
Plasma exchange or immunoglobulin
What is the motor endplate?
The synapse between the motor neuron and the muscle
IV drug users are at risk of this presynaptic disorder
Botulism (can get it from black tar heroin)
Treatment for myasthenia gravis
Acetylcholinesterase inhibitor - pyridostigmine
Thymemctomy
How does pyridostigmine work?
Stops acetylcholinesterase working
Smallest contractile unit of skeletal muscle
The muscle fibre
