51 Cerebral Blood Flow | Trigonocephaly INTRODUCTION Trigonocephaly caused by prenatal closure of the metopic suture is the second most common form of single-suture craniosynostosis.1 Patients present within a sliding scale of severity in phenotype, depending on the timing of suture closure. It remains a subject of discussion, which degree of severity is clinically relevant for a surgical indication. Nowadays, patients with moderate and severe phenotypes undergo surgical correction of the frontal bones and supraorbital rims, aiming for unrestricted brain development, to reduce the risk of neurodevelopmental disorders and to improve aesthetics. Nevertheless, preoperatively, less than 2 percent of the trigonocephaly patients have papilledema as a sign of intracranial hypertension.2 Moreover, preoperative trigonocephaly patients show a normal intracranial volume in comparison to healthy, aged-matched controls.3 Lastly, it was shown that patients with trigonocephaly are at risk of developing mental deficiencies/disorders, behavioral problems, and delays in speech and language, which was also the case for the milder phenotypes which were not operated.4, 5 Taking all the above together, it remains unknown what the added value of surgery is in trigonocephaly with respect to future brain development. The exact mechanism of the association between trigonocephaly and suboptimal neurodevelopmental outcome is not fully understood.6 Although some have suggested that brain development is impaired as a result of the synostosis, others hypothesize that the increased prevalence of neurodevelopmental disorders in these patients is caused by an intrinsic brain disorder. The former hypothesis of restricted brain development caused by synostosis could be reflected in altered cerebral blood flow.7-10 Brain perfusion in trigonocephaly patients was examined previously with single-photon emission computed tomography, and a lower perfusion was reported in the frontal lobe preoperatively compared to postoperatively and to the rest of the brain.9, 10 These two studies offered qualitative evaluation of relative perfusion values only, however. Despite the development of more advanced magnetic resonance imaging techniques to measure cerebral perfusion, this original claim has not been reassessed yet. Arterial spin labeling magnetic resonance imaging is a technique that provides injectionfree measurements of absolute brain perfusion with quantitative accuracy and precision comparable to that of H2015 positron emission tomography. 11 Arterial spin labeling has previously been used for several pediatric applications (e.g., vascular diseases, tumors, epilepsy, seizures) to detect cortical hyperperfusion or hypoperfusion.12 The main advantages of the arterial spin labeling technique are that it measures absolute perfusion and does not require intravenous contrast agent injection.13 Craniosynostosis patients present a further challenge given the skull deformations of these patients.8, 14, 15 The aim of this study was to reassess the previous claims of perfusion changes in craniosynostosis subjects to gain more insight into the hypothesis of brain restriction 3
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