Abstract
To evaluate the patients with cervical spinal cord dysfunction, we studied the potentials elicited from the first dorsal interosseous muscle (FDI) by magnetic stimulation with a double cone coil over the inion (In-MsEP). When the coil was placed at this site, the corticospinal tract was likely to be stimulated at the level of the foramen magnum (Ugawa et al., 1994). The M-waves and F-waves were also recorded from the FDI in response to electrical stimulation of the ulnar nerve at the wrist. Peripheral motor conduction time (PMCT) was determined using the formula as: PMCT (ms)=(M-wave latency+F-wave latency-1)/2, where one millisecond was subtracted from the F-wave latency to allow for the reaction time at the anterior horn cell. The difference between PMCT and the latency of In-MsEP was taken to represent cervical cord conduction time (CCCT).
We examined nine healthy adult volunteers and four patients with cervical myelopathy.
The CCCT was significantly (p<0.05) longer in the patients (3.7±0.3ms) than in the healthy volunteers (1.6±0.7ms), reflecting the damage to the cord in cervical myelopathy. It was suggested that this non-invasive method could be used to periodically monitor cervical cord dysfunction.
