Surgical anatomy of the craniofacial dysostoses: insights from CT scans

Six patients with midface retrusion secondary to craniofacial dysostoses were evaluated by computer assisted tomography (CT) before and after surgery. Computer reformated life-size images were generated for linear measurements and for assessing the encroachment upon the orbit of the anterior and middle cranial fossae, the lateral displacement of the ethmoids, and the retrusion of the maxilla. Dynamic ocular CT demonstrated alterations in the angle of divergence of the optic nerve with globe movement which made measurements of that angle an unreliable assessment of hypertelorism. Surgical separation of the midface from the base of the skull was shown to be a fracture within the palatine bones between its horizontal and pyramidal processes. The integrity of the antral walls was preserved in all patients, in contrast to the comminution seen with traumatic LeFort III fractures. CT evaluation of patients with midface retrusion has further defined the nature of their anomalies, facilitated operative planning, demonstrated the osteotomies in vivo and reduced radiation exposure.