NEUROCRANIAL MORPHOLOGY IN MANDIBULOFACIAL DYSOSTOSIS (TREACHER-COLLINS SYNDROME)

An abnormal cranial base could exert a negative influence on neurocran ial development. Because patients with mandibulofacial dysostosis (MFD ) present an abnormal cranial base (basilar kyphosis), a retrospective mixed longitudinal cephalometric study was designed with the purpose of ascertaining the presence of abnormalities of neurocranial form and size in this population of patients. The lateral and frontal cephalom etric radiographs from 33 patients with MFD (15 males, 18 females) ran ging in age from 3 years 4 months to 19 years 6 months were used. For comparison cephalometric radiographs from two samples were obtained: o ne from 24 children (12 male, 12 female) with repaired cleft lip only, and the other from 41 normal young adults (21 male, 21 female). All f ilms were traced, and 9 linear, 1 angular, and 3 derived measurements were obtained from the neurocranium and cranial base. Differences betw een groups according to age and sex were tested with Student's t-test at the 5% level of significance. A correlation analysis between the cr anial base angle and selected neurocranial variables was also conducte d. The results showed that although the neurocranium in MFD had normal dimensions in length, height, and volume, it had an abnormal shape. T he neurocranium had reduced length anteriorly and increased length pos teriorly. The upper cranial height was decreased and the lower cranial height was increased. The difference in shape was evident during chil dhood and remained in adulthood. The dimensions of the anterior and po sterior cranial base, as well as the cranial base angle, were smaller in MFD. A significant negative correlation was found between the crani al base angle and the lower cranial height in MFD.