Monday, 20 September 2010

MRCP revision battle 16.4: Lambert Eaton Syndrome

Lambert-Eaton syndrome is a rare condition affecting voltage-gated calcium channels which results in:
  • muscular weakness that improves with activity
  • autonomic symptoms (dry mouth, constipation, impotence)
  • hyporeflexia

It is most commonly a paraneoplastic phenomenon, usually due to small cell lung cancer (very rarely due to breast or ovarian cancer).  It can also be autoimmune.

Treatment is 3,4 diaminopyridine.

Regular CXR should be performed as Lambert-Eaton may preceed the development of small cell lung cancer by up to 4 years.

Notice how although both MG and Lambert-Eaton are characterised by muscle weakness there are lots of differences - weakness gets worse on repetition in MG but better in LE, reflexes are normal in MG but reduced in LE and there may be autonomic symptoms in LE but not MG.  Also not involvement of occular muscles is far more common in MG.

Lets now diversify to something completely different - hemiballismus...