133 Ventriculomegaly and TH | Crouzon FM (TH, referred to as positive numbers; eg, tonsil position of 5mm or more past the FM: TH ≥ +5mm), and measured as a continuous variable. Increases in tonsil position referred to increasing downward movement of the cerebellar tonsils. Additionally, TH was divided into two categories: TH < +5mm and TH ≥ +5mm below FM. Presence of abnormal venous anatomy was determined using MRI or CT-scans with angiography. We determined presence of occipital and mastoid emissary veins (0 = normal drainage pattern, 1 = abnormal emissary veins). Clinical Measurements Head-circumference was measured using the occipitofrontal circumference, which has shown to be a reliable indicator for intracranial volume.16, 17 Fundoscopy was performed to screen for ICH as determined by presence of papilledema. Patients were screened preoperatively, at the ages of 2, 4, and 6 years. Polysomnography was used to screen for the presence of OSA, using clinical in-house assessments, and ambulatory sleep studies. Obstructive apnea-hypopnea index (oAHI) was calculated as the number of obstructive and mixed apneas, or obstructive hypopneas with desaturation/arousal, divided by the total sleep duration of one night. The oAHI was used to classify patients in two categories: (1) no/mild (oAHI < 5), and (2) moderate/severe OSA (oAHI ≥ 5). Only head-circumference and early lambdoid suture closure were different on preliminary analysis between children with and without TH ≥ 5mm and children with and without FOHR ≥ 0.4, and were used for further statistical analysis. Information about the timing and types of surgeries was collected. Statistical Analysis Relevant characteristics of the study population are summarized using mean and range, or when appropriate median an interquartile range (IQR), for continuous variables and counts and proportions for categorical variables. To give an overview of the data, we created a heatmap, in which patients were categorized into four groups based on the moment TH ≥ +5mm developed: (1) patients who developed TH ≥ +5mm before first vault expansion, (2) patients who had no TH ≥ +5mm on first MRI, and later developed it, (3) patients who underwent first MRI at a late age and had TH ≥ +5mm, and (4) patients without TH ≥ +5mm. For each of these groups, the heatmap shows the frequency of patients with FOHR ≥ 0.4, lambdoid suture synostosis before 1 year of age, papilledema, venous emissary veins, and moderate/severe OSA. To investigate the association between FOHR and tonsil position, head-circumference, and lambdoid suture synostosis before 1 year of age, we fitted a mixed-model assuming FOHR to follow a beta distribution conditional on the covariates. To allow for nonlinear trajectories over time, we included the children’s age using natural cubic splines with three degrees of freedom. Because this leads to difficulties in interpreting the effects of age directly, the effect of age is displayed in figures to facilitate interpretation. 8
RkJQdWJsaXNoZXIy MTk4NDMw