Unusual neurophysiological and immunological findings in myasthenia gravis: a case report.

We describe the case of a male patient with ocular myasthenia gravis who developed a diabetic neuropathy similar to chronic inflammatory demyelinating polyradiculoneuropathy associated with transient generalized 'myokymic' discharges and distal weakness. He had antibodies against acetylcholine receptor and GQ1b ganglioside, but not anti-voltage-gated K(+) channel antibodies. Serial electrophysiological and immunological findings showed that diabetes was involved in the immune-mediated mechanism of peripheral neuropathy. We hypothesize that the concomitant appearance of distal motor weakness and decreased compound muscle action potentials upon repetitive nerve stimulation, together with increased distal motor latency and generalized peripheral nerve hyperexcitability, were all related to transient serum positivity to anti-GQ1b antibodies.