Objective: To investigate the patterns of the temperature effect on motor nerve conduction parameters according to various warming methods and to obtain the most valuable method of warming in clinical setting.

Method: Twenty normal subjects were studied. After limb cooling in cold water, the cooled hands were warmed by hot pack, fan heater, and whirl pool. The median motor responses were recorded at abdnctor pollicis brevis after the stimulation at the wrist during warming at 1 min interval until the temperature increment reached plateau. We measured the temperature changes and conduction parameters were measured at each examination.

Results: The time constants for temperature increment and distal motor latency, duration, area of compound muscle action potentials showed shorter tendency by hot pack and whirl pool than by fan heater (p＜0.05). For the measurement of distal motor latency, time constant of whirl pool (2.49⁑1.21 min) was shorter than that of fan heater (7.12⁑3.12 min) or hot pack (5.96⁑1.98 min) (p＜0.05).

Conclusion: These findings suggest that the use of whirl pool is the most effective method for warming of the cooled limb.

Objective: The purpose of this study was to determine the difference of temperature effects on the nerve conduction variables and to obtain correction factors for temperature in demyelinated and normal peripheral nerves.

Method: The compound muscle action potentials (CMAPs) were recorded with wrist stimulation during cooling and warming in 10 control subjects and 13 subjects with demyelinating neuropathies. The temperature of cooling and warming were 18^oC and 40^oC, respectively. The time of cooling and warming were 60 minutes and composed of successive 4 sessions of 15 minutes. The skin temperature of thenar area, latency, amplitude, duration, and area of CMAPs were measured before and after each session of 15 minutes of cooling or warming.

Results: The time constants of parameters of CMAPs were of higher tendency in cooling than in warming. The time constants of latency of CMAP were higher in subjects with demyelinating neuropathy than in controls (p＜0.05): 33.3⁑4.0 minutes versus 27.2⁑2.2 minutes in cooling; 30.0⁑7.8 minutes versus 19.6⁑3.3 minutes in warming. The temperature correction factor of latency of CMAPs was ⁣0.23⁑0.03 msec/^oC in control and ⁣0.33⁑0.06 msec/^oC in subjects with demyelinating neuropathies (p＜0.05).

Conclusion: When studying a subject with demyelinating neuropathies, we should warm the extremity for more sufficient time than in normal subject, or may applicate a differenct temperature correction factors.