NMJ disorders Flashcards
what are the 4 neuromuscular junction disorders
myasthenia gravis
lambert eaton myasthenia syndrome
botulism
neuromyotonia (NMT aka isaacs disease)
which NMJ is most common (still rare tho lol)
myasthenia gravis
what type of condition is myasthenia gravis
autoimmune
what are the antibodies in myasthenia gravis produced in response to
in respone to ACh receptors in the post synaptic NMJs
what symptom does reduced ACh receptors in NMJ cause
weakness and fatigue (bc the muscles have less effective channels)
what NMJ disorder is associated with thymoma
myasthenia gravis
who gets myasthenia gravis (2 groups of people)
30yo females
70yo males
which NMJ disorder presents with ocular involvement, worse as day goes on
myasthenia gravis
presentation of myasthenia gravis
ocular involvement (diplopia, ptosis), worse as day goes on
weakness of proximal muscles
bilateral facial weakness, cant chew at end of meal
fatigue, worse as day goes on
what are reflexes like in myasthenia gravis
normal
do symptoms get better or worse as day goes on in myasthenia gravis
worse - more tired
investigations for myasthenia gravis
anti-ACh antibodies
anti-muscle specific kinase (MUSK) antibody
CT thorax - for thymoma
treatment of myasthenia gravis
anticholinesterase eg pyridostigmine
immunosuppressants - steroid, azathioprine
what type of condition is lambert eaton
autoimmune
what are the autoantibodies in response to in lambert eaton
what does this cause
Ca+ channels in NMJ = decreased vesicle release = muscle weakness
how does the muscle weakness differ in lambert eaton in comparison to myasthenia gravis
myasthenia gravis - worse as day goes on
lambert eaton - better after exercise
what cancer is lambert eaton associated wit h
small cell lung cnacer
treatment of lambert eaton
anticholinesterase eg pyridostigmine
K+ channel blockers eg diaminopyridine
IVIg
CXR - for lung SCC
causes of botulism
toxin - food poisoning, infections,
what does the botulinum toxin do to NMJ
cleaves pre synaptic proteins = irreversibly inhibits ACh release
how does botulism present
paralysis difficulty swallowing drooping eyelids NO sensory loss rapid change
can you treat botulin
probs nah, most die
what is wrong in neuromyotonia (isaacs syndrome)
action potential is longer than normal in NMJ
presentation of neuromyotonia (isaacs syndrome)
cramps
stiffness
muscle twitches (fasciculations)
treatment of neuromyotonia (isaacs syndrome)
anti convulsants eg carbamazepine
