The bone defects in patients with cleidocranial dysplasia chiefly involve the clavicles and skull, although wide variety of anomalies may be found in other bones. The clavicles are absent, either unilaterally or bilaterally, in about 10% of all cases. More commonly, the clavicles show varying degrees of hypoplasia a malformation
The muscles associated with the abnormal clavicles are underdeveloped. The patient's neck appears long the shoulders are narrow and show marked drooping The absence or hypoplasia of the clavicles leads to an unusual mobility of the patient's shoulders. In some instances, the patient can approximate the shoulders in front of the chest (Fig. 14.6). Although the clavicular defects result in variations of the associated muscles, function is remarkably good.
The appearance of the patient affected by cleidocranial dysplasia often is diagnostic. The patients tend to be of short stature and have large heads with pronounced frontal and parietal and bossing. Ocular hypertelorism broad base of the nose with a depressed nasal bridge often are noted. On skull radiographs, the sutures and fontanels show delayed closure or may remain open throughout the patient's life. Secondary centers of ossification appear in the suture line and many wormian bones may be seen. Abnormal development of the temporal bone and tube may lead to conductive or sensorineural hearing loss