The anomalous hyoid; review of the literature and report of a case.

Abstract

Although the roentgen ray affords the most informative single means of study of the hyoid apparatus, only two case reports were found in the radiologic literature concerning its anomalies (1, 3), both calling attention to anomalous ossification in the stylohyoid ligaments, with no mention of anomaly of the hyoid bone itself. Such reports as have appeared in the general medical literature deal almost entirely with anomalous long styloid processes and ossified stylohyoid ligaments, though Puchowski (4) reported a case in which there was anomalous ossification in the hyothyroid ligaments as well. Anomalous long styloid processes are said to be encountered in one of every 3,000 tonsillectomies (2). Forty-four cases of complete ossification of the stylohyoid ligaments have been reported. In the case to be recorded here, an anomalous hyoid bone was associated with elongated styloid processes and ossifications in the stylohyoid and hyothyroid ligaments. A search of the literature disclosed no similar example. Report of case A white male, 39 years of age, had suffered for the past twenty-five years from attacks of pain in the right side of the neck radiating to the external occipital protuberance. The attacks, lasting one or two days, occurred at intervals of three to six months. They were initiated by resting on the right side of the neck or by a sudden twist of the head to the right. Associated with the pain were moderate dysphagia and tenderness internally in the lateral pharyngeal wall and externally over the right half of the hyoid apparatus. Roentgen study showed the body of the hyoid bone to be about 50 per cent larger than usual (Fig. 2). The combined length of the styloid process and ossified stylohyoid ligament was 6.5 cm. bilaterally. The right greater cornu of the hyoid bone stood 1.5 cm. higher in the neck than the greater cornu on the left (Fig. 3) and consisted of a horizontal segment (0.6 × 4.0 cm.) and a vertical segment (1 × 3 cm.) inseparably fused into a 7-shaped bone. The vertical segment formed a conspicuous joint with a bone (1 × 1 cm.) replacing the right superior cornu of the thyroid cartilage. The distal centimeter of the left greater cornu of the hyoid bone (0.4 × 4.0 cm.) was angulated 40° downward, backward, and outward and approached to within 0.2 cm. of the backward, upward, and outward angulated superior cornu (0.4 × 1.5 cm.) of the thyroid cartilage (Figs. 1 and 2). Comment In man the hyoid bone is the only bone which normally forms no joint with other bones. It has a considerable range of up-ward, downward, backward, and forward mobility. When, however, the stylohyoid and/or hyothyroid ligaments are partially or completely ossified, the mobility of the hyoid bone is interfered with and the hyoid apparatus becomes less flexible, so that exceptional stresses may produce symptoms. In the case reported here, the styloid processes measured 3 cm. longer than normal.