Neurology. 2023 Oct 17:10.1212/WNL.0000000000207766. doi: 10.1212/WNL.0000000000207766. Online ahead of print.
BACKGROUND AND OBJECTIVES: Neonatal brain injury is a common and devastating diagnosis conferring lifelong challenges for children and families. The role of mechanical forces applied to the head, often referred to as “birth trauma”, are often considered though evidence for this association is lacking. The objective of this study was to investigate the association between common types of neonatal brain injury and scalp swelling using a novel method to quantify scalp swelling as an unbiased proxy for mechanical forces applied to the head.
METHODS: Case-control study using population-based, prospectively collected tertiary care center databases and healthy controls from the Human Connectome Development Project.
INCLUSION: infants born 32-42 weeks gestational age and MRI in the first 9 days.
OUTCOMES: healthy neonates, hypoxic ischemic encephalopathy (HIE) with or without brain injury, or stroke (ischemic or hemorrhagic). Volume of scalp swelling was objectively quantified by a novel imaging method blinded to brain injury. Variables included mode of delivery and use of instrumentation.
STATISTICAL TESTS: Kruskal-Wallis test, chi square, multivariable and multinomial logistic regression.
RESULTS: There were 309 infants included (55% male): 72 healthy controls, 77 HIE without brain injury on MRI, 78 HIE with brain injury, and 82 with stroke (60 ischemic, 22 hemorrhagic). Scalp swelling was present in 126 (40.8%, 95% CI 35.2-46.5%) with no difference in proportions between outcome groups. Median volume was lower in healthy controls (2.4mL, IQR 1.1-5.6) than those with HIE with brain injury (RRR 1.1, 95% CI 1.05-1.2), HIE without brain injury (RRR 1.1, 95% CI 1.06-1.2) and hemorrhagic stroke (RRR 1.1, 95% CI 1.05-1.2), but not ischemic stroke (RRR 1.1, 95% CI 0.99-1.2). Scalp swelling was associated with instrumented delivery (OR 2.1, 95% CI 1.0-4.1), but not associated with increased odds of brain injury in those with HIE (OR 1.5, 95% CI 0.76-3.30). Scalp swelling measures were highly reliable (ICC=0.97).
DISCUSSION: “Birth trauma” quantified by scalp swelling volume was more common in infants with difficult deliveries but not associated with greater odds of brain injury due to hypoxia or stroke. These results may help parents and practitioners to dissociate the appearance of trauma with the risk of brain injury.