[Microneurographic study of sympathetic nerve activity of the lower leg in lumbar spine diseases].

Sympathetic nerve activity was recorded with micro-neurography, and this activity in lumbar spine disease was evaluated. The recording was made with 2-5 omega impedance tungsten microelectrodes in human common peroneal nerve. Sympathetic nerve activity was expressed as bursts numbers per minute, and bursts per 100 heart beats. For the skin sympathetic nerve activity, reflex latencies were 0.80 +/- 0.16 seconds. These values were clearly longer than those of myelinated A fiber, reflecting the conduction velocities of unmyelinated C fiber that forms postganglionic sympathetic fiber. Muscle sympathetic nerve activity in lumbar spine disease with leg symptoms increased in comparison with other subjects. These results suggest this condition induces latent ischemia of the leg that may cause coldness or numbness in the leg.