Brain growth rates in craniosynostotic rabbits

Objective: It has been suggested that abnormal brain morphology or growth r ates may be a primary causal factor of craniosynostosis due, In part, to a lack of normal growth stretch and tension at the sutural margins. The purpo se of the present study was to quantify cerebral hemisphere morphology and growth in a rabbit model of nonsyndromic coronal suture synostosis to deter mine whether cerebral dysmorphology is primary or secondary to synostosis i n this model. Design: Fifty-seven brains (114 hemispheres) were examined from 40 normal c ontrol rabbits and 17 rabbits with bilateral coronal suture synostosis rang ing in age from 25 to 450 days postconception (synostosis occurs at approxi mately 23 days postconception in this model), The calvariae were removed, t he brains were tired in 10% paraformaldehyde, and in situ bilateral measure ments of cerebral hemisphere length and cerebral hemisphere width were obta ined using a Wild microscope with a camera lucida attachment and digital ca liper, Regression analysis was used to compare cerebral cortex growth rates by age between the two groups. Results: Cerebral hemisphere width and cerebral index regression line slope s had similar y intercepts (23 day postconception) with significantly (p <. 05) diverging slopes over time. Normal rabbits increased more rapidly than synostosed rabbits. No significant (p >.05) differences were noted in regre ssion line slopes between groups for cerebral hemisphere length by age or l ength by width. Conclusions: Cerebral dysmorphologies are probably a compensatory, secondar y (postsynositolic) event and not a primary causal factor of craniosynostos is in this rabbit model of human familial, nonsyndromic coronal suture syno stosis.