[Rapid recovery of chronic inflammatory demyelinating polyneuropathy induced by steroid pulse therapy--changes in nerve conduction].

A 47-year-old female patient with chronic inflammatory demyelinating polyneuropathy started to recover from her numbness and weakness within a few hours following the commencement of intravenous methylprednisolone 1,000 mg. In parallel with the recovery of muscle strength, a prolonged latency time of the M-wave was normalized within a day by a revival of the new motor units with a normal latency. In many cases with CIDP, it has been recognized that the gradual decrease in latency time over weeks is a later phenomenon following early increase in amplitude of the M-wave during recovery of weakness, which is explained by remyelinating process. On the other hand, the revival of motor units with a normal latency time from demyelinating conduction block is difficult to explain by remyelinating process, because remyelinating fibers usually have a very slow conduction velocity. Some minor morphological changes of paranodes or humoral factors may be partly responsible for development conduction block in CIDP.