Intracranial hypertension in syndromic craniosynostosis:Prevalence, detection, pathophysiology and treatment

This thesis highlights several aspects regarding the clinical course and treatment of syndromic craniosynostosis. First, we evaluate the prevalence of (syndromic) craniosynostosis: how many children are born with this rare condition in the Netherlands? Thereafter, we focus on the detection of (risk factors for) elevated intracranial pressure: can we use the head circumference as a reliable indicator of the intracranial volume? Can we improve the detection of intracranial hypertension by adding retina scans to the follow-up protocol? Also, the consequences of raised intracranial pressure are assessed: do we see changes in brain cortical thickness? Or in the retinal thickness and/or visual acuity? Finally, we evaluated the treatment protocol for Muenke and Saehtre-Chotzen syndrome: how do we prevent and treat raised intracranial pressure in these syndromes? Should we focus on intracranial hypertension only?<br/

Quantitative detection and follow-up of intracranial hypertension in craniosynostosis:an optical coherence tomography study

BACKGROUND/PURPOSE: To evaluate in craniosynostosis: 1) the diagnostic accuracy of fundoscopy and optical coherence tomography (OCT) to detect intracranial hypertension (ICH); 2) the time course of retinal thickness after treatment of ICH; and 3) the relation between high hyperopia (HH) and fundoscopy/OCT scan findings.METHODS: Syndromic, multisuture, unicoronal, unilambdoid and sagittal synostosis patients visiting our national center were included in this longitudinal cohort study and formed a consecutive series. Retinal layers on OCT, OCT fundus image and fundoscopy were evaluated. ICH was scored according to presence of abnormal intracranial pressures, hydrocephalus, progressive cerebellar tonsillar herniation or fingerprinting and growth arrest. Diagnostic accuracy of OCT, fundoscopy and fundus image, the time course of retinal thickness after ICH and interference of HH were analyzed using linear mixed models.RESULTS: 577 OCT scans in 307 patients were included. ICH was found in 7.2%. Combining total retinal thickness (TRT), OCT fundus image and fundoscopy resulted in a sensitivity of 76% and 81% specificity to detect signs of ICH. TRT was increased in patients who have had signs of ICH versus patients who never had signs of ICH (β+44.9 µm in patients who have had ICH, 95%CI 9.0-80.8,P=0.01). TRT decreased to normal in the years after surgery (β -3.6 µm/year, 95%CI -7.2 - -0.05, P=0.047). There were greater odds of having increased TRT in patients with HH (OR 2.9, 95%CI 1.1-7.6,P=0.03).CONCLUSIONS: The correlation between TRT, OCT fundus image, fundoscopy and particularly for the combination of these parameters with ICP surrogate markers is fair. Increased TRT in the presence of a clinical suspicion of ICH warrants further screening.</p

Cerebral cortex maldevelopment in syndromic craniosynostosis

AIM: To assess the relationship of surface area of the cerebral cortex to intracranial volume (ICV) in syndromic craniosynostosis. METHOD: Records of 140 patients (64 males, 76 females; mean age 8y 6mo [SD 5y 6mo], range 1y 2mo–24y 2mo) with syndromic craniosynostosis were reviewed to include clinical and imaging data. Two hundred and three total magnetic resonance imaging (MRI) scans were evaluated in this study (148 patients with fibroblast growth factor receptor [FGFR], 19 patients with TWIST1, and 36 controls). MRIs were processed via FreeSurfer pipeline to determine total ICV and cortical surface area (CSA). Scaling coefficients were calculated from log‐transformed data via mixed regression to account for multiple measurements, sex, syndrome, and age. Educational outcomes were reported by syndrome. RESULTS: Mean ICV was greater in patients with FGFR (1519cm(3), SD 269cm(3), p=0.016) than in patients with TWIST1 (1304cm(3), SD 145cm(3)) or controls (1405cm(3), SD 158cm(3)). CSA was related to ICV by a scaling law with an exponent of 0.68 (95% confidence interval [CI] 0.61–0.76) in patients with FGFR compared to 0.81 (95% CI 0.50–1.12) in patients with TWIST1 and 0.77 (95% CI 0.61–0.93) in controls. Lobar analysis revealed reduced scaling in the parietal (0.50, 95% CI 0.42–0.59) and occipital (0.67, 95% CI 0.54–0.80) lobes of patients with FGFR compared with controls. Modified learning environments were needed more often in patients with FGFR. INTERPRETATION: Despite adequate ICV in FGFR‐mediated craniosynostosis, CSA development is reduced, indicating maldevelopment, particularly in parietal and occipital lobes. Modified education is also more common in patients with FGFR

Intracranial hypertension and cortical thickness in syndromic craniosynostosis

Aim: To evaluate the impact of risk factors for intracranial hypertension (ICH) on cerebral cortex thickness in syndromic craniosynostosis. Method: ICH risk factors including papilloedema, hydrocephalus, obstructive sleep apnea (OSA), cerebellar tonsillar position, occipitofrontal circumference (OFC) curve deflection, age, and sex were collected from the records of patients with syndromic craniosynostosis (Apert, Crouzon, Pfeiffer, Muenke, Saethre-Chotzen syndromes) and imaging. Magnetic resonance images were analysed and exported for statistical analysis. A linear mixed model was developed to determine correlations with cerebral cortex thickness changes. Results: In total, 171 scans from 107 patients (83 males, 88 females, mean age 8y 10mo, range 1y 1mo–34y, SD 5y 9mo) were evaluated. Mean cortical thickness in this cohort was 2.78mm (SD 0.17). Previous findings of papilloedema (p=0.036) and of hydrocephalus (p=0.007) were independently associated with cortical thinning. Cortical thickness did not vary significantly by sex (p=0.534), syndrome (p=0.896), OSA (p=0.464), OFC (p=0.375), or tonsillar position (p=0.682). Interpretation: Detection of papilloedema or hydrocephalus in syndromic craniosynostosis is associated with significant changes in cortical thickness, supporting the need for preventative rather than reactive treatment strategies

Saethre–Chotzen syndrome: long-term outcome of a syndrome-specific management protocol

Aim: To assess the long-term outcomes of our management protocol for Saethre–Chotzen syndrome, which includes one-stage fronto-orbital advancement. Method: All patients born with Saethre–Chotzen syndrome between January 1992 and March 2017 were included. Evaluated parameters included occipital frontal head circumference (OFC), fundoscopy, neuroimaging (ventricular size, tonsillar position, a

The occipitofrontal circumference: reliable prediction of the intracranial volume in children with syndromic and complex craniosynostosis

Object Patients with syndromic and complex craniosynostosis are characterized by the premature fusion of one or more cranial sutures. These patients are at risk for developing elevated intracranial pressure (ICP). There are several factors known to contribute to elevated ICP in these patients, including craniocerebral disproportion, hydrocephalus, venous hypertension, and obstructive sleep apnea. However, the causal mechanism is unknown, and patients develop elevated ICP even after skull surgery. In clinical practice, the occipitofrontal circumference (OFC) is used as an indirect measure for intracranial volume (ICV), to evaluate skull growth. However, it remains unknown whether OFC is a reliable predictor of ICV in patients with a severe skull deformity. Therefore, in this study the authors evaluated the relation between ICV and OFC. Methods Eighty-four CT scans obtained in 69 patients with syndromic and complex craniosynostosis treated at the Erasmus University Medical Center-Sophia Children's Hospital were included. The ICV was calculated based on CT scans by using autosegmentation with an HU threshold < 150. The OFC was collected from electronic patient files. The CT scans and OFC measurements were matched based on a maximum amount of the time that was allowed between these examinations, which was dependent on age. A Pearson correlation coefficient was calculated to evaluate the correlations between OFC and ICV. The predictive value of OFC, age, and sex on ICV was then further evaluated using a univariate linear mixed model. The significant factors in the univariate analysis were subsequently entered in a multivariate mixed model. Results The correlations found between OFC and ICV were r = 0.908 for the total group (p < 0.001), r = 0.981 for Apert (p < 0.001), r = 0.867 for Crouzon-Pfeiffer (p < 0.001), r = 0.989 for Muenke (p < 0.001), r = 0.858 for Saethre-Chotzen syndrome (p = 0.001), and r = 0.917 for complex craniosynostosis (p < 0.001). Age and OFC were significant predictors of ICV in the univariate linear mixed model (p < 0.001 for both factors). The OFC was the only predictor that remained significant in the multivariate analysis (p < 0.001). Conclusions The OFC is a significant predictor of ICV in patients with syndromic and complex craniosynostosis. Therefore, measuring the OFC during clinical practice is very useful in determining which patients are at risk for impaired skull growth

First vault expansion in Apert and Crouzon-Pfeiffer syndromes: Front or back?

Background: Children with Apert and Crouzon-Pfeiffer syndromes are at risk of intracranial hypertension. Until 2005, when the authors switched to occipital expansion, their institution's preferred treatment was fronto-orbital advancement. However, it was still unclear whether (1) occipitofrontal head circumference (i.e., intracranial volume) was greater after occipital expansion than after fronto-orbital advancement; (2) the incidences of tonsillar herniation and papilledema were lower; and (3) visual acuity was better during follow-up. In these patients, the authors therefore compared fronto-orbital advancement with occipital expansion as the first surgical procedure. Methods: Measurements included repeated occipitofrontal head circumference as a measure for intracranial volume; neuroimaging to evaluate tonsillar herniation; funduscopy to identify papilledema; and visual acuity testing. Results: The authors included 37 patients (Apert syndrome, n = 18; Crouzon-Pfeiffer syndrome, n = 19). Eighteen underwent fronto-orbital advancement and 19 underwent occipital expansion (age at surgery, 1.0 versus 1.5 years; p = 0.13). Follow-up time in both groups was 5.7 years. The increase in occipitofrontal head circumference (+1.09 SD) was greater after occipital expansion than after fronto-orbital advancement (+0.32 SD) (p = 0.03). After occipital expansion, fewer patients with Crouzon-Pfeiffer syndrome had tonsillar herniation (occipital, three of 11; fronto-orbital advancement, seven of eight; p = 0.02); for both syndromes together, fewer patients had papilledema (occipital, four of 19; fronto-orbital advancement, 11 of 18; p = 0.02). Visual acuity was similar after fronto-orbital advancement and occipital expansion (0.09 versus 0.13 logarithm of the minimum angle of resolution) (p = 0.28). Conclusions: The authors' preference for occipital expansion as the initial craniofacial procedure in Apert and Crouzon-Pfeiffer syndromes is supported by the greater increase it produces in intracranial volume (as evidenced by the occipitofrontal head circumference), which reduces the incidences of tonsillar herniation and papilledema