Sonographic investigation of the laryngeal anatomy of the healthy child

OBJECTIVE To study the anatomy and the performances of normal pediatric larynx on ultrasonography. METHODS Firstly, confirmed the ultrasonographic features of thyroid cartilage, arytenoid cartilage, cricoid cartilage, epiglottic cartilage, preepiglottic space, paraglottic space, false vocal fold, vocal fold and scoop muscle in three pediatric cadaver larynxes by compared tissue sections at the same level. Then, 33 normal children were enrolled and their sonographic appearances of larynx were studied. RESULTS The thield like thyroid cartilage and the leaf-shaped epiglottis were isoechoic and could be seen on sonography in both the sagittal and transverse planes. The hypoechoic arytenoid cartilages, looked like sickle in the transverse planes and irregular triangle in the sagittal planes. Cricoid cartilage was isoechoic structures, like n shape in the transverse planes, while the sides of the cricoid cartilage looked like rectangular structures in the sagittal planes. Preepiglottic and paraglotic spaces were hyperechoic. Vocal folds, corresponding to the internal layers of thyroarytenoid muscles, were symmetrical and isoechoic. The thin mucous membrane appeared hyperechoic on the surface. False vocal folds manifested as paired hyperechoic and triangular structures. Their echogenicity was related to their glandular and fat contents. CONCLUSION The ultrasonographic features of the thyroid cartilage, arytenoid cartilage, cricoid cartilage, epiglottic cartilage, pre-epiglottic space, paraglottic space, false vocal fold, vocal fold and scoop muscle could be clearly demonstrated.