Prevalence of subdural collections in children with macrocrania

Abstract

Background and purpose: The relationship between enlarged subarachnoid spaces and subdural collections is poorly understood and creates challenges for clinicians investigating the etiology of subdural collections. The purpose of this study was to determine the prevalence of subdural collections on cross sectional imaging in children with macrocephaly correlating with subarachnoid space enlargement.

Materials and methods: The radiology information system of a large pediatric medical center was reviewed for "macrocrania" and "macrocephaly" on reports of cranial MRI/CT examinations in children <24 months of age, over a 24-month period. Head circumference was obtained from the clinical record. Studies were reviewed blindly for subdural collection presence and subarachnoid space size. Children with prior cranial surgery, parenchymal abnormalities, hydrocephalus, or conditions predisposing to parenchymal volume loss were excluded. Chart review was performed on those with subdural collections.

Results: Imaging from 177 children with enlarged head circumference was reviewed. Nine were excluded, for a final cohort of 168 subjects (108 with enlarged subarachnoid space). Subdural collections were identified in 6 (3.6%), all with enlarged subarachnoid space (6/108, 5.6%). In 4, subdural collections were small, homogeneous, and nonhemorrhagic. In 2, the collections were complex (septations or hemorrhage). Two children were reported as victims of child abuse (both with complex collections). No definitive etiology was established in the other cases.

Conclusions: The prevalence of subdural collections in imaged children with macrocrania was 3.6%, all occurring in children with enlarged subarachnoid space. Our results suggest that enlarged subarachnoid space can be associated with some subdural collections in this cohort. Despite this, we believe that unexpected subdural collections in children should receive close clinical evaluation for underlying causes, including abusive head trauma.

Fig 1.

Case 3. A, Axial FSE T2-weighted image. B, Axial proton density–weighted image. C, Coronal FSE T2-weighted image; 8-month-old girl. Clinical indicatin for examination: macrocrania. Typical small homogeneous subdural collection, similar to those identified in cases 2, 5, and 6. Note diffuse prominence of subarachnoid spaces. Small left frontal vertex subdural collection is identified (arrows), slightly hyperintense to CSF on T2-weighted images (A and C), and moderately hyperintense to CSF on proton density images (B). The collection was isointense to CSF on T1-weighted images and showed no blooming on gradient-echo sequences. Follow-up CT 3 months later showed decrease in prominence of the subarachnoid space, normal ventricles, and no evidence of subdural collection.

Fig 2.

Case 4. A, Axial CT image. B, Axial FSE T2-weighted image. C, Axial proton density–weighted image. D, Axial gradient recalled-echo image. E, Sagittal T1-weighted image. F, Axial gradient-echo image: 3-month-old boy with macrocrania. Initial CT examination (A) demonstrates moderate sized bilateral subdural collections (arrows), slightly hyperattenuated relative to CSF. MRI examination was performed 14 hours later. Bilateral subdural collections are again identified (white arrows, B, C, and D) hyperintense to CSF on both T2 and proton density–weighted images (B and C). A thin septation is identified on the right (black arrow, B). A layering region of decreased T2 signal is seen on the right (arrowhead, B), which was hyperintense to CSF on T1-weighting (not shown) and blooms on the gradient-echo sequence (arrowhead, D) compatible with blood products. A localized area of increased signal on T1-weighted images in the right parietal vertex subdural collection was noted (arrowhead, E), which was hyperattenuated to brain on CT (not shown) and exhibited blooming on the gradient-echo sequence (arrowhead, F) consistent with additional blood products.