We report a case of neuromuscular disease overlap between myasthenia gravis and 
Lambert-Eaton syndrome (LES). Clinical features were those of LES and occurred 
insidiously in this 68-year old man: proximal weakness predominant in the lower 
limbs, generalized areflexia, dryness of the mouth and partial right eye palsy. 
Investigations disclosed a small cell lung cancer. On the other hand, an 
electrophysiological study showed low amplitude of all motor evoked potentials, 
and significant decrement in the median nerve at repeated 3 Hz stimulation, but 
failed to disclose any increment of the motor evoked potential in abductor 
digiti minimi pedis muscle after both maximal voluntary contraction and repeated 
20 Hz stimulation. In addition, the patient improved under anticholinesterase 
drugs, but failed to respond to guanidine. Titres for both 
anti-acetylcholine-receptor antibodies and calcium channel antibodies were 
negative. The relationship between our case and recently reported cases of 
co-existence of the Lambert-Eaton myasthenic syndrome and myasthenia gravis is 
discussed.