Does Parkinson's disease interfere with electromyographic fatigue of masticatory muscles?

Parkinson's disease is a neurodegenerative disease with manifestations related to oxidative stress and damage to the skeletal striated musculature. This study evaluated the electromyographic fatigue of the masseter and temporal muscles in individuals with Parkinson's disease. The median frequency of the normotensive electromyographic signal was analyzed in 16 individuals, aged between 50 and 70 years, with Parkinson's disease in stages I and III of the Hoehn and Yahr disability scale (n=8) or without the disease (n=8). The data were tabulated and analyzed statistically (t-test, p .05). Compared with the group without Parkinson's disease, the group with the disease showed an increase in the median frequency, with significant differences for the right masseter (p=.05) and the right temporal (p=.03) muscles. The results suggest that there is a link between Parkinson's disease and functional alterations of the masticatory system, especially when electromyographic fatigue is assessed.

Effect of congenital blindness on EMG activity of the facial muscles.

The aim of this work was to analyze electromyographically the facial muscles: orbicularis oris (upper and lower fascicles), orbicularis oculi (right and left lateral portions) and frontal, in blind and clinically normal (control) individuals, in various clinical conditions. Electromyographic averages of all data collected were normalized by maximal voluntary contraction of the studied muscles and statistical analysis was performed by Student's t test, using "Statistical Package for the Social Sciences" software--SPSS 12.0 (Chicago, IL). It was found that electromyographic alterations occur in the facial musculature that influences facial expressions of individuals. Results for the orbicularis oris muscle demonstrated that myoelectric activity among blind and control subjects was greater for the control group at muscular rest, blowing, and in labial projection. Electromyographic analysis of the orbicularis oculi among blind and control subjects in three clinical conditions studied demonstrated that activity was greater for the control group at muscular rest, blinking, and forced blinking. For the frontal muscles were demonstrated that electromyographic activity was greater for blind individuals. These data suggest the influence of congenital blindness on muscular development, including alterations in electromyographic activity of skin musculature in individuals with visual impairment.