AGE-RELATED-CHANGES IN INTRACRANIAL VOLUME IN RABBITS WITH CRANIOSYNOSTOSIS

Neurocapsular growth is highly heritable and determines neurocranial f orm. Although craniosynostosis alters brain growth direction, resultin g in compensatory changes in the neurocranium, it is believed that suc h compensations occur without reduction in intracranial volume. This h ypothesis was tested in a rabbit model with nonsyndromic, familial cor onal suture synostosis. Skulls of 56 rabbits (20 normals, 20 with dela yed onset synostosis, and 16 with complete synostosis) were scanned us ing three-dimensional computed tomography at 6 and 18 weeks of age. In tracranial contents were reconstructed, and indirect intracranial volu me was calculated. Qualitatively, re-formations of intracranial conten ts from completely synostosed rabbit skulls exhibited the typical ''co pper beaten'' morphology. Quantitatively, intracranial volume was sign ificantly (I < 0.05) reduced in rabbit skulls with complete synostosis compared with both control rabbit skulls and rabbit skulls with delay ed onset synostosis at 6 weeks by 11 percent and 14 percent, respectiv ely). By 18 weeks, intracranial volume in rabbit skulls with synostosi s was significantly (P < 0.05) reduced (by 12 percent in complete syno stosis and 8 percent in delayed onset synostosis) compared with normal rabbits. Results suggest that in rabbits with uncorrected craniosynos tosis, compensatory changes in the neurocranium were not adequate to a llow normal expansion of the neurocapsular matrix. Further research is needed to determine whether reduction in intracranial volume was a re sult of neural tissue deficiency or cerebrospinal fluid (i.e., ventric ular or subarachnoid) space compression in this model.