This thesis shows the complexity of the course of patients with craniosynostosis. To answer the question if brain development in craniosynostosis is led by intrinsic brain abnormalities or the potential effect of ICH: the brain development is affected by both intrinsic genetic causes as well as the effect of ICH and its interconnected problems, such as hydrocephalus and tonsillar herniation. Further research is necessary to understand the clinical course and outcome in patients of non-syndromic craniosynostosis as well as the clinical course and outcome in patients with syndromic craniosynostosis. Finally, future studies should focus on to optimize the individual surgical treatment and to predict the clinical neurocognitive outcome.