Myasthenia gravis, muscle twitch, hyperhidrosis and limb pain associated with thymoma: proposal of possible new myasthenic syndrome.

We describe a 54-year-old man with myasthenia gravis, thymoma, systemic muscle twitch particularly of both lower limbs, hyperhidrosis and lower limb pain. The muscle twitch resembled to fasciculation rather than to myokymia and was persistent after discontinuation of anti-acetylcholinesterase drug. No attenuation nor disappearance of the muscle twitch was educed by spinal anesthesia. However, it disappeared when a nondepolarizing type muscle relaxant (pancuronium bromide) was used. The muscle twitch was thus considered to originate from peripheral axons. Thymoma was considered to be involved in the pathogenesis of these unusual clinical manifestations which may constitute a new myasthenic syndrome.