Lambert-Eaton myasthenic syndrome (LEMS)

Question 1

Lambert-Eaton myasthenic syndrome has a similar set of features to myasthenia gravis - in which of these conditions are the features more severe?

Answer 1

Myasthenia gravis

Question 2

1) LEMS typically occurs in patients with what condition?
2) Autoantibodies are generated against what?

Answer 2

1) Small-cell lung cancer
2) Voltage-gated calcium channels in the presynaptic terminal

Question 3

Name 2 features of LEMS

Answer 3

• Gait difficulty followed by eye signs (diplopia and ptosis)
• Autonomic involvement: dry mouth, constipation and impotence
• Slurred speech
• Dysphagia
• Reduced tendon reflexes

Question 4

1) What drug can be used as symptomatic relief if LEMS?
2) How does it work?

Answer 4

1) Amifampridine
2) Blocking voltage-gated potassium channels in the presynaptic cells, which in turn prolongs the depolarisation of the cell membrane and assists calcium channels in carrying out their action