Lambert-Eaton Myasthenic Syndrome

Question 1

Aetiology

Answer 1

typically w small cell lung cancer

Question 2

Pathophysiology

Answer 2

Immune system produces antibodies directed towards voltage gated calcium channels in the small cell lung cancer cells but also towards voltage gated ca channels in the presynaptic terminal of the NMJ

Question 3

Presentation?

Answer 3

• Same as MG, however symptoms develop more slowly
• post-tetanic potentiation
  
  • reduced tendon reflexes normally however after a period of strong muscle contraction, reflexes become temporarily normal

Question 4

Mx

Answer 4

• treat underlying malignancy
• older person who has been chronic smoker presents with these symptoms –> investigate for SCLC
• Amifampridine
  
  • _​_increases ACh in NMJ by blocking pre synaptic potassium gated voltage channels

Other options:

• Immunosuppression
• plasma exchange
• IV immunoglobulins