Electromyographic analysis of lip muscle function in operated cleft subjects.

EMG activity of the upper lip was measured with bipolar surface electrodes during speech and nonspeech tasks in order to assess labial function in subjects with repaired clefts. Eighteen patients between 15 and 23 years of age with repaired unilateral cleft lip (isolated or combined with repaired cleft palate) were compared to 24 matched noncleft subjects. Data analysis demonstrated that the amplitude of action potentials of the upper lip was significantly greater in the cleft group. We hypothesize that the enhanced activity of the repaired upper lip during function may contribute to the facial growth abnormalities usually seen in the cleft population.