Lambert-Eaton myasthenic syndrome without anti-calcium channel antibody: adverse effect of calcium antagonist diltiazem.

A 59 year old man with ischaemic heart disease, developed the clinical and electromyographic changes of the Lambert-Eaton myasthenic syndrome after taking calcium antagonist, diltiazem. The symptoms appeared periodically with a rise and fall in serum level of diltiazem. Extensive search was made for systemic neoplasms and autoimmune diseases without success. Serum antibody to voltage operated calcium channel was not detected.