BACKGROUND: Intracranial birth-related subdural hemorrhage frequently occurs in asymptomatic newborns and has no adverse long-term sequelae. It is medically and medicolegally important to differentiate birth-related subdural hemorrhage from other pathological causes of intracranial hemorrhage. There is limited literature available on the incidence of birth-related subdural hemorrhage, its imaging features, and evolution over time, mainly because asymptomatic infants do not routinely undergo cranial MRI.
OBJECTIVE: To establish the incidence and distribution of birth-related subdural hemorrhage and evaluate their association with various modes of delivery, identify associated features, and evaluate the sequential evolution of signal changes of the birth-related hemorrhages on MRI.
MATERIALS AND METHODS: A total of 200 healthy term neonates and young infants were included in this retrospective review study. All infants underwent MRI of the brain and cervical spine at postnatal age of 0-2 months with acquisition of a 3D T1-weighted (T1W), 3D or 2D T2-weighted (T2W), and axial diffusion-weighted imaging (DWI) sequences. The scans were evaluated for the presence and distribution of subdural hemorrhages, other intracranial hemorrhages, and associated injuries. Prevalence of intracranial hemorrhage in various modes of delivery was analyzed. Relationship between the signal intensities of the bleeds on T1W, T2W, and DWI scans and the age of the infants was analyzed. Appropriate tests were applied to test for statistical significance of the data.
RESULTS: Out of 200 neonates, 66 (33%) had detectable intracranial hemorrhage on MRI with an age range of 11-25 days, including 31 (47%) males and 35 (53%) females. All of them had subdural hemorrhages, 54 (81.8%) of which were in the posterior fossa. Additional parenchymal hemorrhages were present in a few, but no subarachnoid hemorrhages, cervical spinal canal hemorrhages, cortical bridging vein injury, or cervical spinal ligamentous injury were identified within the limitations of the study. No detectable intracranial hemorrhage was found in subjects above 25 days of age. Overall incidence of subdural hemorrhage by mode of delivery was 8/68 (11.8%) in babies born by cesarean section and 58/132 (43.9%) in babies born by vaginal delivery. Among the vaginal deliveries, the highest incidence was observed in assisted vaginal delivery (19/30, 63.3%). Subjects with birth-related subdural hemorrhage were categorized into three age groups: <13 days, 13-21 days, and >21 days. All detected hemorrhages were T1W hyperintense. In the <13 days group, all bleeds were T2W hypointense. In the 13-21 days group, 73.1% were T2W hypointense, while 26.9% were T2W mixed. All bleeds in the >21 days group were T2W hypointense. All DWI hyperintense bleeds were found in the 13-21 days group.
CONCLUSION: Birth-related subdural hemorrhage occurs in over a third of normal deliveries and has a characteristic distribution, predominantly in the posterior fossa. Associated cervical spinal subdural hemorrhages, cervical spinal ligamentous injury, or cortical bridging vein injury, which are concerning for traumatic etiology, were not identified. Birth-related subdural hemorrhages follow a characteristic pattern of signal changes on MRI. Although not completely reliable, this can help in differentiating them from traumatic intracranial hemorrhages which usually occur postnatally. No birth-related subdural hemorrhages were seen after 25 days of age in our cohort.