Abstract
Ultrasonic examination was applied to assess the nasopharyngeal function. The present report shows the results of a basic study on ultrasonic observation of the lateral pharyageal wall (LPW) in normal subjects by means both of real time ultrasound scan and M-scan.
1) Analysis of the nasopharyngeal closure p osition in lateral and posterior-anterior cephalometric radiograph shows that the maximum medial excursion of the LPW occurs at the level of the full length o f the elevated velar.
2) The ultras ound crystal was placed against the neck at a position slightly under the ear and behind the ramus of the mandible. So that the ultrasonic beam would be directed toward the LPW position, the re must be an angle of 10°-16° against frontal plane and 18°-20° against Frankfort horizontal plane.
3) The dynamic movement of LPW during speech, as viewed by the real time ultrasound scan, was very similar to that seen on a frontal video-fluoroscopic examination.
4) During the production of /a/, the medial movement of the upper level of the LPW is seen, and the LPW is shaped like an arc. However, the /i/ vowels showed an upward vertical and /or slight lat e ral movement of the lower part of the LPW, so the LPW is shaped like an inverse S.
5) Blowing showed the same patterns of medial movement of the LPW during pron unciation. However, during swallowing, medial movement is different from pronunciation, and maximum medial exc u rsion of the LPW over a wide extent is seen.
6) The M-mode echo curve allows the relative displacement of a reflecting interface of the LPW at the region of the nasopharyngeal closure, and is measured by quantitative analysis.
7) There was a tendency for the moved distance of the LPW for swallowing > plosive consonants and blowing > vowels > nasal consonant.
8) The starting point of the LPW movement occurs before the beginning of voice, and the point of maximum movement is observed in vowels after, and in plosive consonants before the beginning of voic e.
9) The speed of the medial movement of the LPW could calculated in the M-mode echo curve.
10) The time for swallowing was 1341msec on average.
11) Both the real time ultrasound scan and M-scan proved to be useful in diagnostic analysis qualitative and quantitative.
