12 Chapter 1 Examples of single suture synostosis include scaphocephaly (sagittal suture synostosis), trigonocephaly (metopic suture synostosis) and posterior plagiocephaly (lambdoid suture synostosis). When two of more skull sutures are fused without any other congenital abnormalities, it is defined as multisutural/complex craniosynostosis. In 24% of the cases, craniosynostosis is syndromic, which means single (usually the coronal suture) or multiple skull sutures are fused in combination with additional congenital abnormalities, such as facial anomalies and malformations of the hands and feet.9 Syndromic craniosynostosis is caused by mutations in various genes.9 The most distinct craniosynostosis syndromes are: Apert, Crouzon-Pfeiffer, Muenke and Saethre-Chotzen syndromes. The diagnosis of craniosynostosis is primarily made based on the anamnesis and physical examination and confirmed by a 3D-CT scan.10, 11 Intracranial pressure According to the Monro-Kellie doctrine, the cranial vault is a closed box and contains the sum of the 3 main components of intracranial volume: brain tissue, intracerebral blood, and cerebrospinal fluid (CSF) (Figure 2a).12 The intracranial pressure (ICP) represents the net effect of intracranial volume and content, brain compliance, plus blood- and cerebrospinal fluid dynamics in this closed box.13 14 If there is a conflict between growth in brain volume and skull restriction, it has its effect on the brain, cerebral blood volume (CBV), CSF and in consequence on the ICP.15-17 As the brain grows in a fused fault, brain growth and arterial blood supply will be maintained as much as possible, depending on compensatory mechanisms like relocating CSF to the spinal compartment and faster discharge of blood to the extra cranial compartment by collaterals (Figure 2b). In patients with craniosynostosis, skull growth may be reduced while both compensatory mechanisms may fail. Figure 2a.) Craniosynostosis Brain Figure 2b.) Craniosynostosis brain during growth Intracranial volume Looking at the skull with its intracranial volume, literature shows that initially the intracranial volume of sCS patients is normal and enlarged in Apert patients, which
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