Craniofacial changes in hemifacial microsomia

Cephalometry, X-ray cephalometry, and somatoscopy were used in the studies of 65 adult males with a severe unilateral microtia subdivided into three groups: with marked asymmetry, with slight asymmetry, and without any obvious facial asymmetry. The group with marked asymmetries was designated as hemifacial microsomia. In this group the affected side of the face was depressed on the average from above and from below towards the level of the external auditory canal. The center of the anteroposterior reduction was situated in the region in front of the pterygomaxillar fissure. The anteroposterior and vertical facial dimensions on the affected side were reduced most markedly, while the width dimensions showed the slightest changes. Hypoplasia was most severe within the lower face and increased towards the otocephalic centre. The mandibular joint was displaced in an anteroinferior and medial direction. Hypertelorism did not occur, but the orbit on the affected side was smaller in height and was frequently vertically dislocated. The facial profile was unchanged except for retrusion of the chin and increased frequency of bite disorders. The mobility of the mandible was limited. Hemihypoplasia also exerted an influence on structures that were not of branchiogenic origin, e.g., the cranial base (narrowing, asymmetry, and more pronounced curvature), the neurocranium (depression in mastoid and tympanotemporal regions, posterior rotation of the vault), and the frontonasal component (deviation of the nose and premaxilla). The cranial vault and the bottom of the occipital bone showed on the average no asymmetries. The similar character of deviations in slightly affected groups revealed that in spite of the high variability of changes typical for branchiogenic malformations the development of the face in these defects was subjected to certain rules. Marked facial asymmetry occurred only in every fifth patient with a severe degree of microtia, while definite signs of asymmetry were absent in every third patient.