[Central motor conduction time using magnetic and vibratory stimulation in Parkinson's disease, especially in patients with rigidity].

Rigidity, tremor, akinesia and disorder of postural reflex are the main clinical features of Parkinson's disease. We presented the mechanism underlying rigidity and assessed central motor conduction time (CMCT) using magnetic, with or without vibratory, stimulations. Basal ganglia, especially, the internal pallidum, and the thalamus play major roles in the mechanism of rigidity in Parkinson's disease. Hyperexcitability of the spinal motor nucleus due to low threshold has been recognized. Magnetic stimulation is painless and is simpler than electric stimulation. Therefore, this method is used clinically for evaluating conduction disturbance of the upper motor neurons in multiple sclerosis, cerebrovascular disease and so on. CMCT measured by magnetic and/or electric stimulation may be abbreviated or normal in Parkinson's disease, according to the literature, though controversy persists in this regard. In our study, CMCT was normal in Parkinson patients. However, CMCT was reduced in patients with rigidity and tremor. Furthermore, in a portion of the patients, CMCT was further abbreviated by also applying vibratory stimulation. These observations support the hypothesis that cells in the thalamus, cortex and spinal cord and/or pathways in these portions of the central nervous system are excitable or activated in Parkinson patients with rigidity and tremor. However, elucidation of the mechanisms underlying rigidity and tremor awaits further investigation.