160 Chapter 9 Comparable with previous studies of Crouzon patients, half of the patients in our cohort needed a second or third expansion after initial skull expansion.20 The number of patients requiring midface correction was comparable to other findings.23 Ten of the 16 patients with available MRI developed tonsillar herniation (63%), which is more than the rate for CAN patients in the literature (24%) but in line with the reported prevalence of Chiari malformation in Crouzon patients (38%–70%).4, 22, 24 Taken together, all of the data in this study suggest that CAN patients show the same severe clinical course as that in Crouzon patients. This study is a first effort to collect data from multiple centers on a rare form of complex craniosynostosis. Treatment protocols showed differences among centers and changed over the years. The number of patients and the details on clinical signs and outcome were insufficient to statistically evaluate these protocols. However, some remarks can be made. In general, little has been studied with respect to the timing and order of interventions. Renier et al. suggest avoiding the insertion of a shunt shortly before or after skull expansion because of the anticipated restriction on skull growth.25 I n t he current study, early shunting seemed to be associated with more skull expansions (2) than late (1.5) or no (1.3) shunting. However, this finding may well reflect the complexity of the patients presenting with hydrocephalus early in their disease course rather than being an effect of any protocol. On the contrary, patients undergoing early cranial expansion (before the age of 1) less frequently entered into a trajectory of hydrocephalus treatment. Again, this finding may reflect the severity of the patients’ courses rather than any protocol. Furthermore, this sequence of initial expansion with late or no hydrocephalus treatment may have been at the expense of macrocephaly and turricephaly. Also, the number of shunt revisions was higher after secondary shunting. This finding may be related to inserting a shunt in an already operated field or to local shunt-insertion protocols. FMD is indicated to resolve signs of brainstem compression or a syrinx but may have a role in improving CSF outflow from the fourth ventricle and thus reducing the need for shunting. However, in the current study, the reported shunt/ETV cases were similar in the patients with or without FMD (5/7 vs 8/12). Overall, it seems that the timing and order of interventions may influence the number of surgeries required, but their effect cannot be differentiated from the impact of a severe clinical presentation in this limited number of patients. To answer the question of what timing and which sequence of interventions generate the best functional and cosmetic outcomes with the smallest number of interventions, larger and more detailed studies are necessary. Especially clear definitions of clinical signs and surgical indications and a structural follow-up for skull growth and shape, signs of raised intracranial pressure, and long-term emotional, behavioral, and cognitive development will help to compare and understand different treatment philosophies. International collaborations such as the European Reference Networks can be great facilitators in performing such research.
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