We encountered a very rare case of adult laryngeal anomaly accompanied by positional and morphological abnormalities of the hyoid bone and dysplasia of the strap muscle.
The case was a 35-year-old female, and the major complaint was slight hoarseness. At the time of the first examination, a belt-like eminence, which was more elevated and harder to the touch at the proximal end, was noted visually near the sternal region of attachment of the left strap muscle. Upon palpation, the hyoid bone was found to be located lower than its normal position, and moreover, the left greater horn of the hyoid bone was unclear to the touch. As the laryngopharyngeal findings, the anterior commissure showed right lateral displacement. The left plica ventricularis looked swollen, and the left vocal cord was difficult to see. However, movement of the left arytenoid region was limited in comparison with the right region and the left piriform fossa was shallow and narrow.
Soft-tissue radiography of the neck, hypopharyngo-esophagography, CT scan, etc., revealed abnormalities of the hyoid bone. That is, the right greater horn was thin and slanted sharply from the right posterosuperior region to the left anteroinferior region, the body of the hyoid bone was thick and in contact with the thyroid cartilage, and the left greater horn was in an almost horizontal position from that point of contact. In addition, dysplasia of belt-like hyperplasia was seen in the left strap muscle. This case was diagnosed as laryngeal deviation to the right due to the above anomalies.
The etiology of laryngeal anomalies in this case were considered from the embryological viewpoint. On the basis of our experience with the reported case, we learned that morphological abnormalities, such as laryngeal anomalies, can be a cause of idiopathic laryngeal deviation.
