An electromyographic study of the orbicularis oris muscle of cerebral palsied spastic hemiplegics

Abstract

The orbicularis oris muscle of fourteen individuals including seven cerebral palsied spastic hemplegics and seven normal individuals with Class I occlusion was examined electro-myographically to determine any differences in muscle activity on the right and left side of the lips. The age range was between eight years and seventeen years. No limitations were placed on age, sex, or race since the purpose of the study was to determine any differences in activity between the right and left sides of the orbicularis oris muscle. A six channel Polygraph Grass Model 5A was used with paired surface electrodes attached to each quadrant of the lips and connected to four channels of the Polygraph. When the lips were at rest, no muscle activity was detected for either group. When the lips were tested during voluntary swallowing, involuntary swallowing associated with straw drinking and holding the lips together, the activity was fairly equal and symmetrical in the normal group. However, in the cerebral palsied spastic hemiplegics, there was increased muscle activity in the orbicularis oris muscle on the hemiplegic side.