A Novel Phenotype of Calvarial Thickening and Increased Rates of Craniosynostosis in Children with Bronchopulmonary Dysplasia
Zachary D. Zapatero, Christopher L. Kalmar, Mychajlo S. Kosyk, Liana Cheung, Kathleen A. Nilan, Anna R. Carlson, Andrew C. Calabria, Arastoo Vossough, Shih-Shan Lang, Jordan W. Swanson, Huayan Zhang, Jesse A. Taylor, Scott P. Bartlett
The Children's Hospital of Philadelphia, Philadelphia, PA
Background Calvarial thickening has been documented as a sequela of many different types of conditions, including but not limited to genetic syndromes, hematologic, endocrinologic, and neurologic disorders. The purpose of this study was to describe a novel phenotype of calvarial thickening we have observed in a subset of patients with bronchopulmonary dysplasia (BPD) which has not been previously reported.
Methods: Patients admitted to the CHOP NICU and treated by the medical chronic lung disease team between July 2015 - August 2020 were retrospectively reviewed. Inclusion required a head computed tomography (CT) scans to determine the presence of calvarial thickening. Electronic medical records were comprehensively reviewed. Head CTs with 3mm thick slices or less were analyzed on Materialise Mimics v22 (Materialise, Ghent, Belgium). Bone masks were generated, and manual segmentation was used to isolate the frontal, parietal, temporal, and occipital bones. Bone thickness maps were created and average thickness was recorded. Data were analyzed with appropriate statistics.
Results: Fifty-eight patients had head CTs available. The estimated gestational age was a median of 25 weeks [IQR 24, 27]. A minority of patients underwent head CT for abnormal cranial morphology (n= 15, 25.9%). Calvarial thickening greater than expected for age was identified in 28 (48.2%) patients, 12 (42.9%) of which had premature suture fusion while only 5 (16.7%) of the unaffected patients had premature suture fusion (p=0.029). Twenty-two affected patients (78.6%) and 16 unaffected patients (53.3%) met inclusion for thickness analysis. There was no difference in age at CT scan (Thick phenotype: median 283 days [IQR 251, 345] vs normal: median 292 days [IQR 120, 586]; p=0.554). The median average thickness was significantly thicker in the affected cohort than the unaffected cohort in the frontal (median 6.3 mm [IQR 5.0, 7.3] vs median 3.1 mm [IQR 2.0, 4.4]; p<0.001) parietal (median 4.5 mm [IQR 3.5, 5.4] vs median 2.5 mm [IQR 1.6, 3.3]; p<0.001) temporal (median 4.4 mm [IQR 3.1, 5.0] vs median 2.6 mm [IQR 2.2, 2.9]; p<0.001) and occipital bones (median 4.3 mm [IQR 3.6, 5.4] vs median 2.9 mm [IQR 1.9, 4.0]; p=0.002) Conclusions A subset of patients with BPD develop a thickened skull with higher rates of premature sutural fusion than their unaffected counterparts. Further investigation hopes to identify patient-specific and treatment factors associated with the development of calvarial thickening and whether or not the premature suture fusion represents true craniosynostosis.
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