Spontaneous development of bilateral subdural hematomas in an infant with benign infantile hydrocephalus: color Doppler assessment of vessels traversing extra-axial spaces

Abstract

We present an infant with macrocrania, who initially demonstrated prominent extra-axial fluid collections on sonography of the brain, compatible with benign infantile hydrocephalus (BIH). Because of increasing macrocrania, a follow-up sonogram of the brain was performed; it revealed progressive enlargement of the extra-axial spaces, which now had echogenic debris. Color Doppler US showed bridging veins traversing these extra-axial spaces, so it was initially thought that these spaces were subarachnoid in nature (positive cortical vein sign). However, an arachnoid membrane was identified superior to the cortex, and there was compression of true cortical vessels beneath this dural membrane. An MRI of the brain showed the extra-axial spaces to represent bilateral subdural hematomas. The pathogenesis of spontaneous development of the subdural hematomas, in the setting of BIH, is discussed. We also emphasize that visualizing traversing bridging veins through extra-axial spaces does not necessarily imply that these spaces are subarachnoid in origin.

Prevalence of Subdural Collections in Children with Macrocrania

“…We could find only 12 previously reported spontaneous, nontraumatic SDC in children with prior imaging documentation. 7,20,26,[31][32][33] The best documented of these reports is from Amodio et al, 20 who described a 3.5-month-old, former 32-week preterm boy, with grade 1 germinal matrix hemorrhage presenting with macrocrania. Initial head ultrasound examination demonstrated enlarged extra-axial spaces but no SDC.…”

“…7,8,10,20 In these studies, a total of 14 cases of SDC in the setting of enlarged SS have been described. All were investigated, but only 1 was thought to be related to AHT.…”

“…Differentiation of enlarged SS and SDC was made on the basis of standard imaging findings. 3,16,20,21 Results were compared with the clinical imaging report, and discrepancies were reviewed by another boardcertified radiologist with added qualification in pediatric radiology and a pediatric neuroradiology fellowship (M.C.). Remaining discrepancies were resolved by consensus opinion.…”

Benign external hydrocephalus: a review, with emphasis on management

“…The proposed cause is stretching of the bridging veins traversing the enlarged subarachnoid space [5, 83, 141]. …”

Prevalence and Evolution of Intracranial Hemorrhage in Asymptomatic Term Infants

“…This finding suggests that though not typical in a neonate, prominent extra-axial space is a predisposing factor for SDHs as has been reported by other authors. [32][33][34][35] Although SDH along the interhemispheric fissure, parafalcine in location, is widely associated with NAI, we would suggest that the pattern and location of SDH alone should not be used to make a distinction between SDH due to NAI or birth injury. In the pilot study of Holden et al, 21 there is a description and illustration of an interhemispheric SDH in an asymptomatic neonate.…”