Disorders of NMJ Flashcards
Name two PREsynaptic disorders of NMJ
Botulism
Lambert Eaton Myasthenic Syndrome
Which organism causes botulism and where is it found?
Clostridium botulinum
Found in soil
–> food and wounds can be infected
What is botulism?
Rapid onset weakness without sensory loss
Cause by Botulinum Toxin (botox) produced by Clostridium botulinum
What is Lambert Eaton Myasthenic Syndrome?
Antibodies to presynaptic calcium channels leads to less vesicle release –> muscle weakness
Which disease is Lambert Eaton Myasthenic Syndrome strongly associated with?
Small cell lung cancer
What is the treatment for Lambert Eaton Myasthenic Syndrome?
3-4 diaminopyridine
What is the most common disorder of the NMJ and is it pre- or post- synaptic?
Myasthenia gravis
Post synaptic
What is myasthenia gravis?
Autoimmune condition
Acetyl choline receptor antibodies
Reduced number of functioning receptors
–> muscle weakness and FATIGUABILITY
What is the pattern of weakness in myasthenia gravis?
Fluctuating weakness, worsens throughout the day
Fatiguability
Where is the weakness often seen in myasthenia gravis?
Extra-ocular Bulbar (swallowing, chewing, talking) Face Neck Proximal limbs
What signs might you see on examination in myasthenia gravis?
Ptosis
Diplopia
Myasthenia snarl on smile
Normal reflexes
What can worsen symptoms in myasthenia gravis?
Pregnancy Low potassium Infection Over treatment Change of climate Exercise Emotion Drugs
Which drugs can worsen symptoms in myasthenia gravis?
Gentamicin Opiates Tetracycline Quinine Beta-blockers
Which 3 investigations should be done if myasthenia gravis suspected?
Anti-acetyl choline receptor antibodies (seen in 90%)
EMG –> reduced muscle response with repetitive nerve stimulation
CT of thymus (75% have hyperplasia or thymoma)
What is the principle of treatment in myasthenia gravis?
Symptom control
Immunosuppression
