Muscle and neuromuscular junction Flashcards
What kind of motor neurone disorders (lower or upper) present with weakness, low tone and fasiculations?
Lower motor neurone disorders
What neurotramsmitter is released across the neuromuscular junction?
Acetylcholine
What enzyme breaks down acteylcholine?
Acetylcholinesterase
What toxin affects the presynaptic terminal of the neuromuscular junction?
Botulism - Clostridium botulinum
What toxin causes rapid onset weakness but with no sensory loss?
Botulism toxin
What is lambert eaton myasthenic syndrome?
Antibodies form to presynaptic calcium channels and lead to less vesicle release.
What underlying condition is lamber eaton myasethenic syndrome associated with?
Small cell carcinoma
What condition affects the post synaptic terminal of the neuromuscular junction?
Myasthenia Gravis
In what condition do you get antibodies to ACh receptors?
Myasthenia gravis
A man presents with muscle weakness in his face and find his eyes drooping at the end of the day.
Myaesthenia gravis
How do the antibodies in myasthenia gravis cause problems?
- Block binding of ACh
- Trigger inflammatory cascade that damages the folds of the postsynaptic membrane
What other structure has a role in myaesthenia gravis?
Thymus. 75% of patients with MG have hyperplasia or thymoma
What is the drug treatment of choice in myaesthenia gravis?
Acetylcholinesterase inhibitor - pyridostigmine
What surgical treatment is sometimes required in myasethenia gravis?
Thymectomy
What is a fascilation?
A visible fast fine spontaneous twitch
Is a fasciculation usually a sign of disease in the motor neurone or the muscle itself?
Motor neurone
What kind of muscle do fasciculations occur in?
Denervated muscle which becomes overexcitable
What is myotonia?
The failure of muscle relaxation after use
Where is the problem is myotonia?
Chloride channel
Name two imflammatory muscle disease?
Dermatomyositis
Polymyositis
A 54 year old lady comes in complaining of weakness in her things and arms over the last 2 months. Her blood tests show a raised CK
Polymyositis
What is the first line treatment for someone with raised CK?
Steroids
A 54 year old lady comes in complaining of weakness in her things and arms over the last 2 months. On examination she has a rash across her face.
Dermatomyositis
What can dermatomyositis be a sign of?
An underlying malignancy
A 75 year old man comes in complaining of muscle weakness in all his muscles apart from his thumb. He says this has been coming on slowly for about 2 years.
Inclusion body myositis
What is the inheritance pattern on myotonic dystrophy?
Autosomal dominant
A 49 year old women presents with muscle weakness and wasting. She also reports a clouding of her vision and frontal balding. Her mum also had similar symptoms before her death.
Myotonic dystrophy
