Objective evaluation of velopharyngeal function by acoustic reflection measurements.

Objective: To investigate whether acoustic pharyngometry is capable of discriminating velopharyngeal mobility in cleft and non-cleft subjects by determination of epipharyngeal volume changes with active muscle function.

Design: Case control study, consecutive sample.

Setting: Cleft palate rehabilitation centre.

Patients: Thirty-three consecutive cleft palate patients, among them 10 following pharyngeal flap surgery and 32 controls without velopharyngeal pathology.

Intervention: Transnasal acoustic measurements of airway cross-sectional area in the state of relaxed and tensed pharyngeal muscles. Determination of epipharyngeal volume changes by integrating the difference of the airway profile from the choane for a distance of 5 cm (EV0-5). Measurements of defined changes in the epipharynx served as reference.

Results: Acoustic pharyngometry is capable of discriminating (P < 0.05: U test, Mann-Whitney) the volume effect of velopharyngeal mobility in CP patients (6.5 cm3) from the control group (8.0 cm3). A 'pharyngeal flap type' and a 'non-pharyngeal flap type' of restriction was observed. The individual effect of velopharyngoplasty on pharyngeal mobility can thus be determined.

Conclusion: Acoustic pharyngometry is a non-invasive, quantitative investigation technique which seems well suited for the evaluation of velopharyngeal mobility. We expect it to be a helpful tool in objectively monitoring the effect of therapeutic intervention on velopharyngeal mobility, and it may provide a better understanding of the pattern of movement in CP patients.