Lambert-Eaton Myasthenic Syndrome

Lambert-Eaton Myasthenic Syndrome (LEMS):
due to inadequate release of acetylcholine from presynaptic terminals  autoimmune attack against voltage calcium channels; occurs in 60% of those with small cell carcinoma of lung (neurological symptoms occur before tumour symptoms, sometimes up to 5 years)
present with fatigue and proximal muscle weakness that improves with exercise (eyes rarely involved); most >40 years of age
reflexes are reduced, but improve with facilitation
may have autonomic dysfunction
treatment – stimulation of acetylcholine release (eg guanidine hydrochloride); anticholinesterases may improve symptoms