Reliability of the nasopharyngeal fiberscope (NPF) for assessing velopharyngeal function.

Simultaneous side-view nasopharyngeal fiberscopic (NPF) and lateral cinefluoroscopic (cine) recordings were taken for two normal subjects to determine the stability of NPF placement for the study of velopharyngeal function, and the reliability and validity of NPF findings. The results indicate that the NPF was highly stable during the several velopharyngeal activities examined, the NPF tip maintaining a relatively constant relationship within the vertebral complex. Therefore, it seems likely that similar NPF views are obtained on different occasions with a subject. The findings also indicate that measurements can be made from NPF still photos for several aspects of the velopharyngeal mechanism. However, measurements of the left lateral wall movement were not reliable. Measurement of velar movement from NPF correlated well with cine measures of velar movement, indicating validity of that NPF measure.