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It has been suggested that surgical release of synostosed sutures may ameliorate various cranial base abnormalities in craniosynostotic patients. The present study was designed to test this hypothesis in a rabbit model with familial coronal suture synostosis (CSS). Data were collected from 56 New Zealand White rabbits: 32 unaffected controls, 11 with unoperated CSS, and 13 with CSS released by suturectomy performed at 25 days of age. Serial radiographs were taken at 25, 42 and 84 days. Linear, angular and triangular shape cranial base measurements were compared using ANOVA and tensor biometric analysis. Results revealed that at 84 days, both groups of CSS rabbits had significantly (p < 0.05) different anterior and total cranial base lengths, flatter cranial base angles, and dysmorphic anterior cranial base shapes when compared with normals. Significant (p < 0.05) differences were noted only for palatal and cranial base angles and posterior cranial base shape between CSS rabbits with and without suturectomy. However, significant (p < 0.05) changes were noted between pre- and postoperative measurements in posterior and total cranial base lengths and anterior and posterior cranial base shapes in CSS rabbits with suturectomy. Results revealed that surgical release of synostosed coronal sutures through suturectomy did not normalize cranial base growth patterns in CSS rabbits. These findings may be explained by the relatively late age of surgical release or suturectomy site resynostosis with continued dysmorphic cranial base growth. Alternatively, cranial base abnormalities seen in CSS rabbits may be early primary malformations, not secondary deformations amenable to surgical modification.

Approximately 300 to 500 infants per 1,000,000 have prematurely fused cranial sutures (craniosynostosis). Craniosynostosis can result in increased intracranial pressure and craniofacial deformities, which often require extensive and costly craniofacial surgery. Because the neurocranium and basicranium are developmentally interrelated, understanding their influence on one another is important for surgical planning. Although surgery has been found to have long-term effects on the cranial bases of craniosynostotic human beings and rabbits, the biological mechanisms behind these effects remain uncertain. Some researchers have suggested that the surgical release of synostosed sutures alters long-term growth patterns, resulting in cranial base differences between craniosynostotic individuals who undergo surgery and those who do not. Additionally, some investigators have proposed that an acute and surgically related displacement of basicranial elements may contribute to the observed differences. The current study examines acute postoperative changes in four lengths, three angles, and three triangles between cranial base landmarks in a sample of seven New Zealand white rabbits with familial nonsyndromic craniosynostosis. Results indicate that suturectomy caused no statistically significant (P < 0.05) acute length, angular, or shape differences in the cranial base. Thus, previous long-term cranial base differences found between rabbits that were operated on and those that were not were probably not caused by an acute displacement of skeletal elements as a result of surgery. These findings suggest that postoperative cranial base changes may be related more to chronically altered growth patterns than to acutely altered changes in intracranial pressure or dural tension.