Prediction of deterioration of velopharyngeal function associated with maxillary advancement using electromyography of levator veli palatini muscle.

OBJECTIVE

The purpose of the present study was to examine the possibility that postoperative velopharyngeal function following maxillary advancement could be predicted using preoperative electromyography of the levator veli palatini.

DESIGN

Levator muscle electromyography was recorded preoperatively during speech and blowing. Levator activity was expressed as a percentage relative to the maximum value observed throughout the experiment. Postoperative velopharyngeal function was evaluated by means of perceptual judgment and nasoendoscopy.

PARTICIPANTS

The subjects were four patients with repaired cleft palates who underwent maxillary advancement, two by osteotomy and two by distraction osteogenesis. None of the subjects presented with preoperative hypernasality, and nasoendoscopy demonstrated complete velopharyngeal closure in all subjects prior to maxillary advancement.

RESULTS

Preoperative levator activity for speech of two subjects was similar to that for normal speakers (< 60% of total range), and postoperative nasality and nasoendoscopic findings revealed no detectible changes. For the other two subjects, levator activity for speech exceeded 60% of the total range, similar to that of speakers with velopharyngeal incompetence. These subjects showed increased hypernasality and deteriorated velopharyngeal closure following maxillary advancement.

CONCLUSION

The deterioration of velopharyngeal function associated with maxillary advancement was demonstrated for subjects whose levator activity was at higher levels during speech in comparison with maximal activity observed during blowing, regardless of the amount of maxillary advancement. Preoperative levator muscle electromyography could be a predictor in identifying patients at higher risk of postsurgical deterioration of velopharyngeal function.