Decrease in presynaptic inhibition on heteronymous monosynaptic Ia terminals in patients with Parkinson's disease.
OBJECTIVE
Heteronymous Ia facilitation from the quadriceps to the soleus was studied to clarify central motor control through presynaptic inhibition (PSI) on Ia terminals of spinal motoneurons in Parkinson's disease.


METHODS
17 patients with Parkinson's disease and 36 control subjects participated in the study. Because the early part of facilitation reflects the degree of PSI, the extent of facilitation was quantified as the slope, within 0.8 msec of onset.


RESULTS
Heteronymous Ia facilitation in the patients was greater than in the age-matched control participants. PSI was negatively correlated with the walking speed of the patients. In the patients examined twice, lessening of bradykinesia was correlated to a decrease in PSI but not lessening of rigidity.


CONCLUSIONS
These findings indicate that the degree of PSI is decreased and disturbance of the central control of PSI may relate to gait disturbance in Parkinson's disease.
Morita
H
H
The Third Department of Internal Medicine, Shinshu University School of Medicine, Matsumoto, Japan.
Shindo
M
M
Ikeda
S
S
Yanagisawa
N
N
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004558:Electric Stimulation; D005260:Female; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology; D006181:H-Reflex; D006801:Humans; D018476:Hypokinesia / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons; D009127:Muscle Rigidity / Q000209:etiology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology*; D009433:Neural Inhibition; D009475:Neurons, Afferent; D010300:Parkinson Disease / Q000150:complications* / Q000503:physiopathology*; D017729:Presynaptic Terminals; D009435:Synaptic Transmission; D013979:Tibial Nerve / Q000503:physiopathology*