Lambert-Eaton myasthenia is a presynaptic myasthenic syndrome characterised by impaired release of acetycholine from nerve terminals.

60% of patients have small cell lung carcinoma. The usual age of onset in between 50 and 60 years of age. Men are affected more than women.

Electromyography shows increased evoked potentials after repeated galvanic stimulation (the opposite occurs in myasthenia gravis).

The autoimmune aetiology of Eaton-Lambert should be compared and contrasted with myasthenia gravis.