Magnetic Transcutaneous Stimulation of the Motor Pathway in Spinal Cord Disorders

Abstract

Motor evoked potential (MEP) from small hand and foot muscles was measured by the transcranial magnetic stimulation according to Barker’s method. Central motor conduction time (CMCT) was calculated by stimulating over the scalp and then over the cervical and lumbar areas. In healthy subjects, the CMCT (head to neck) was 8.3 ± 1.2 (SD) ms (n = 50) in relaxed muscles and was 6.0 ± 1.4 (SD) ms (n = 29) in partially voluntarily activated muscles, and the CMCT (head to lumbar) was 16.1 ± 3.0 (SD) ms (n = 50) in relaxed muscles and was 14.5 ± 1.2 (SD) ms (n = 29) in partially activated muscles. F wave study was done in 14 patients and (F + M − 1)/2 was calculated according to Kimura’s formula. Clinical study showed that MEP and both CMCT with and without facilitation, and CMCT(F) were significantly prolonged in 18 patients with chronic compression cervical myelopathy and were abnormal in 5 patients with spinal cord injury (n = 23). The CMCT and clinical motor functions were well correlated. The pre- and postoperative data (n = 22) were compared and showed the reasonable results of this new method for measuring the motor function. Side effects were not encountered.