title: Soleus H-reflex inhibition during gait initiation in Parkinson's disease.
abstract: The soleus H-reflex excitability during gait initiation was investigated in Parkinson's disease. Eleven patients participated in this study. Patients stepped forward as soon as the start signal flashed. Soleus H-reflex was evoked from the trailing leg 100, 300, or 600 msec after the start signal. The electromyographic activity in the soleus muscle immediately before evoking the H-reflex and the ankle joint motion were recorded. The soleus H-reflex was inhibited 300 msec after the start signal. The amount of the soleus H-reflex inhibition was inversely correlated with the Hoehn and Yahr stage; Items 14, 29, and 31 of the Unified Parkinson's Disease Rating Scale; and the delay of the onset of the ankle dorsiflexion from the start signal. In contrast, the amount of electromyographic activity immediately before evoking the H-reflex was not significantly correlated with those measures but was significantly correlated with Item 22 of the Unified Parkinson's Disease Rating Scale. Those findings indicate that the amount of soleus H-reflex inhibition during gait initiation depends on the severity of the disease. Abnormality of descending command may be related to the severity-dependent H-reflex inhibition.
authors.affiliation: Department of Physical Therapy, Osaka Prefectural University, Osaka, Japan. hiraoka@osaka-hsu.ac.jp
authors.forename: Koichi
authors.initials: K
authors.lastname: Hiraoka
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Kazuo
authors.initials: K
authors.lastname: Abe
mesh_terms: D000328:Adult; D000368:Aged; D000843:Ankle Joint / Q000503:physiopathology; D004576:Electromyography / Q000379:methods; D005260:Female; D005684:Gait / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009433:Neural Inhibition / Q000502:physiology*; D010300:Parkinson Disease / Q000503:physiopathology*; D013997:Time Factors