Skull vault growth in craniosynostosis

Background: Since its first description by Virchow, the principle of abnormal skull growth due to restriction of skull growth at the fused sutures, and the realisation by Moss that the sutures at the skull base are equally affected, have been the main intellectual driving forces behind the majority of cranial expansion procedures performed currently in children with craniosynostosis. Current observations: Despite original impressions that craniosynostosis leads to craniostenosis, many studies have demonstrated that in the majority of patients with craniosynostosis there is normal skull volume in those over the age of 6 months. In Apert syndrome, skull volume is invariably larger than normal. Some studies have shown that intracranial pressure is independent of intracranial volume, and can exist in the presence of normal volume, or indeed after cranial expansion. These observations imply that cranial expansion procedures create a state of artificially increased skull volume, in the quest to improve appearance and function. Future advances: This creates a new angle of view through which skull growth abnormalities are seen. It is becoming clearer that in most patients with craniosynostosis, there is regional imbalance of skull growth, which co-exists with a variety of other equally important factors, such as genetic defects, raised intracranial pressure, venous hypertension, and other brain parenchymal anomalies such as hindbrain hernia or hydrocephalus. It is becoming increasingly obvious that the type of surgical treatment currently practised in most cases is conceptually incorrect. Recent modifications such as the use of springs or distraction do not escape from the underlying philosophy of cranial expansion. With that in mind, it is hoped that advances in the fields of genetics and molecular biology will provide treatments for the cause of craniosynostosis rather than the symptomatic relief that surgery offers currently. Conclusion: Until then, there is a need to develop better ways of quantifying regional abnormalities of skull growth.