DEVELOPMENT OF A STRAIN OF RABBITS WITH CONGENITAL SIMPLE NONSYNDROMIC CORONAL SUTURE SYNOSTOSIS .2. SOMATIC AND CRANIOFACIAL GROWTH-PATTERNS

In the March 1993 issue of The Cleft Palate-Craniofacial Journal we re ported a female rabbit born in our laboratory with complete bilateral coronal suture (CS) synostosis. This follow-up study presents our atte mpts to breed the animal and establish a strain of craniosynostotic ra bbits. The second part of this study presents longitudinal somatic and craniofacial growth data in offspring with coronal suture synostosis. Serial growth data from 72 animals were collected for the present stu dy. The sample consisted of 11 animals (10 offspring and the original female) with complete nonsyndromic unilateral (plagiocephalic) or bila teral (brachycephalic) CS synostosis, 19 animals with partial CS synos tosis, and 42 unaffected control litter mates. At 10 days of age, all animals had radiopaque amalgam markers placed on either side of the fr ontonasal, coronal, anterior lambdoidal, and sagittal sutures. Body we ights and serial lateral and dorsoventral head radiographs were taken at 1.5 (10 days), 6, 12, and 18 weeks of age. All animals showed simil ar body weights at 1.5 weeks of age, while completely synostosed anima ls exhibited a slight (about 12%), but significantly (p < .001) lowere d body weight by 18 weeks of age. Results revealed that by 1.5 weeks o f age the completely synostosed animals already exhibited brachycephal ic cranial vaults, mid-facial hypoplasia, and increased flattening of the cranial base compared to unaffected siblings. This pattern continu ed through 18 weeks of age, with the partially synostosed animals exhi biting intermediate morphologies. Compensatory overgrowths were noted primarily at the sagittal and frontonasal sutures, especially for comp letely synostosed animals. Findings revealed that the craniosynostotic rabbits followed predictable compensatory craniofacial growth pattern s and exhibited secondary deformities similar to those reported for ca ses of human coronal suture synostosis. Such findings support continue d efforts at developing this model to help understand, in part, the et iopathogenesis of this condition in human populations.