Muscle sympathetic nerve activity in patients with lumbar spinal canal stenosis.

The present study aimed to measure sensory nerve conduction velocity (SNCV) and muscle sympathetic nerve activity (MSA) in both normal subjects and patients with lumbar spinal canal stenosis (LSCS), and to determine what sensory and sympathetic nerve systems relate to the development of abnormal sensation in the lower limbs of the patients. The study population was 12 patients and 10 age-matched healthy control subjects. A statistical difference in the mean MSA intervals was found between the LSCS patients and the normal subjects. There was a fairly large difference between them in the values of the standard deviations as one of the parameters to determine the degree of fluctuation of MSA. These results suggest the LSCS patients have shorter MSA intervals and narrower fluctuations of MSA than normal subjects. As for the range of fluctuation of the MSA intervals and SNCV, the faster the SNCV, the wider the range of fluctuation of MSA intervals in the normal subjects. Many patients with LSCS seem to maintain a correlation between SNCV and MSA intervals. This suggests that even in cases of LSCS, human homeostasis works to keep the relationship between sympathetic nerve function and somato sensory nerve function to some extent. A few LSCS patients showed no correlation between MSA and SNCV. These patients were rather old, suffered spinal stenosis in the relatively higher levels of the spinal canal, and had suffered from the disease for longer than the mean period of all the patients. When the peripheral nerves or cauda epuina are chronically compressed, the nerve systems can not maintain the relationship between them, which finally results in failure. It is suggested that the disrupted coordination between sympathetic nerve function and somato sensory nerve function is one of the reasons why abnormal sensations occur in the lower extremities of LSCS patients.