PARANEOPLASTIC MYASTHENIC SYNDROME

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