Histology and Electromyography of the Levator Veli Palatini Muscle in Patients with Cleft Palate.

概要

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In some patients with cleft palate (CP), velopharyngeal insufficiency persists after palatoplasty. In order to determine whether such insufficiency is due to the pathological changes of the levator veli palatini (LVP) muscle, we examined histologically the LVP muscles of 35 patients with CP and of six control patients with congenital microtia. Electromyographic records were obtained of the LVP muscles of 12 patients with CP after palatoplasty.The muscle structures were well preserved in seven of 35 patients with CP. Among the other 28 patients, perimysial fibrosis was observed in 13, variations in fiber caliber in seven and internal nuclei in one, but these findings were also observed in the control group. The incidence of each finding was not significantly different between the two groups. Electromyography revealed the mean action potential during phonation of the sound "ah" to be 825 μV. Effective elevation of the soft palate was correlated with neither the histology nor the action potential of the LVP muscle.Therefore velopharyngeal insufficiency persisting after palatoplasty is considered not to be due to pathological changes in the LVP muscle.