Syndromes of synaptic transmission of NMJ

Question 1

give some of the symptoms of neuromyotonia

Answer 1

cramps, stiffness, slow relaxation, muscle twitches

Question 2

what type of disease is neuromyotonia considered to be

Answer 2

autoimmune

Question 3

describe the mechanism involved in neuromyotonia

Answer 3

prolonged end plate potential and repetitive action potential discharge in skeletal muscle

Question 4

what drug treatment is used in neuromyotonia

Answer 4

anti-convulsants(eg. carbamazepine), which block voltage gated Na+ channels

Question 5

describe the features that characterise Lambert-Eaton Myasthenic Syndrome(LEMS)

Answer 5

muscle weakness in limbs, very rare and associated with small cell lung cancer

Question 6

describe the mechanism involved in LEMS

Answer 6

in many cases autoimmune, results in reduced Ca2+ entry in response to depolarisation and hence reduced vesicular release of ACh

Question 7

what drugs are involved in treatment of LEMS

Answer 7

anticholinesterases and K channel blockers

Question 8

what symptoms is myasthenia gravis characterised by

Answer 8

progressively increasing muscle weakness during periods of activity, often weakness of eye/eyelid is presenting feature

Question 9

what type of disease are the majority of myasthenia gravis

Answer 9

autoimmune

Question 10

describe the mechanism in myasthenia gravis

Answer 10

reduction in number of functional channels, and therefore reduction in amplitude of end plate potential

Question 11

what is involved in drug treatment of myasthenia gravis

Answer 11

anticholinesterases(eg edrophonium) and immunosuppressants(eg azathiprine)

Question 12

describe the action of anticholinesterases

Answer 12

increase conc. ACh in synaptic cleft