Intracranial volume change in craniosynostosis

Object. There is still controversy regarding the optimum time to perform su rgery for craniosynostosis. Some recommend surgery soon after birth and oth ers delay until the age of 12 months. Intracranial pressure has been measur ed in an attempt to provide a scientific rationale, but many questions rema in unanswered. To date, little attention has been given to intracranial vol ume and its changes during the first few years of life in children with cra niosynostosis. The authors' goal was to focus on intracranial volume during this period and to compare measurements obtained in patients with craniosy nostosis with measurements obtained in healthy individuals. Methods. Using the technique of segmentation, the intracranial Volume of 84 children with various forms of craniosynostosis was measured on preoperati ve computerized tomography scans. The change in average volume that occurs with increasing age was calculated and compared with a model of normal intr acranial volume growth. The age at presentation for children with craniosyn ostosis was 1 to 39 months; 76% of the patients were younger than 12 months . In eight patients in whom only one cranial expansion procedure was perfor med, postoperative intracranial volumes were measured as well. Several inte resting observations emerged. 1) There was little difference in head growth between boys and girls with craniosynostosis during the first few months o f life. After the age of 12 months, however, the difference in intracranial volume normally seen between the two genders was observed in the craniosyn ostosis group as well. 2) Excluding children with complex pansynostosis, wh o have smaller heads, children with all other types of craniosynostosis hav e similar head growth after the Ist year of life, with no difference betwee n the number of and type of suture affected. Children with Apert's syndrome develop greater than normal intracranial volumes after the Ist year of lif e. 3) Although children with craniosynostosis are born with a smaller intra cranial volume, by the age of 6 months volume has reached normal levels, an d from that point on volume follows the pattern of normal head growth. 4) C hildren who presented after the age of 6 months and later developed recurre nt craniosynostosis after initial successful treatment had a small intracra nial Volume at their initial presentation. 5) Of the patients whose postope rative intracranial volumes were measured, all but one had preoperative vol umes at or above normal values, and their postoperative volumes were consid erably higher than normal for their age. These children all followed a grow th curve parallel to that of healthy children but at higher volume value. O ne patient with a smaller-than-normal initial intracranial volume was surgi cally treated at a very young age and, despite cranial expansion surgery, p ostoperative volume did not reach normal levels. It is postulated that this was due to the fact that the operation was performed at a time when cranio synostosis was still active. Conclusions. The results of this study indicate that the underlying mechani sm leading to craniosynostosis and constriction of head volume "exhausts" i ts effect during the first few months of life. Measurement of intracranial volume in clinical practice could be used to "fine tune" the optimum time f or surgery. In late-presenting children, this may be useful in predicting p ossible recurrence.