[Evaluation by microneurography of muscle sympathetic nerve activity in myelopathic patients]

The purpose of this study was to observe the functional condition of the muscle sympathetic nerve activity (MSNA) in nine patients with mild myelopathy for which surgery was indicated [mean score 14/17 by Japanese Orthopaedic Association (JOA) cervical myelopathy and 7/11 for thoracic myelopathy]. The MSNA was obtained from the tibial nerve at the popliteal fossa by microneurography. The resting activities and the responses during handgripping were analyzed and compared with those of a control group of nine healthy volunteers and patients with disorders unrelated to myelopathy. The MSNA with the subjects supine was recorded first at rest for 5 min. (rest period), next during exertion of 20% of the maximum voluntary handgripping power for 5 min. (handgripping period), and last at rest for 5 min. (recovery period). The number of MSNA bursts per min. (burst rate) in the group with myelopathy was more than that in the control group (p < 0.05) in all three periods. The response by MSNA to handgripping in the group with myelopathy was higher than that in the control group at the start of handgripping (p < 0.01), and tended to be higher even 5 min. after handgripping ended. The results appeared to demonstrate that MSNA of patients with mild myelopathy for which surgery is indicated is increased in the lower extremities.