Lambert Eaton Myasthenic Syndrome LEMS


LEMS a.k.a. Myasthenic syndrome


The diagnosis is made by a combination of clinical features, autoantibodies and electrophysiology

Clinical features:

  • Proximal weakness (shoulder and pelvic) and neck muscle weakness
  • Improve with exercise, sometimes this is not clinically detectable
  • Reduced or absent reflexes
  • Cholinergic autonomic failure (dry mouth, constipation, impotence, decreased sweating, blurred vision)

Findings on investigations:

RNST Repetitive nerve stimulation test:

  • at 3 Hz: decremental response
  • at 20-50 Hz: potentiation of response i.e. facilitation
  • Post exercise: potentiation of response i.e. facilitation
  • Anti P/Q VGCC antibodies (Voltage gated Ca++ channel antibodies)

Investigations to consider:

Extensive to rule out cancer


Treat or remove tumor

  • Immunosuppresion:
    • Prednisolone
    • Azathioprine
    • Ciclosporin
  • Immunomodulation:
    • IVIg or Plasmaphoresis
  • Cholinergic drugs:
    • 3,4-diamiopyridine
    • 4-aminopyridine
    • Guanidine hydrochloride side effects: renal failure, bone marrow suppression
    • Antiacetylcholinesterase


  • Drugs that block the neuromuscular junction
  • Ca++ channel blockers

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