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.