The prevalence of subdural blood products in extremely premature infants with no history of abusive head trauma, studied by magnetic resonance imaging around term-equivalent age.

Background: Prematurity and enlarged subarachnoid spaces are both hypothesised to represent an increased risk of subdural haemorrhages (SDHs) in infancy, both with and without a history of abuse.

Objective: To examine the prevalence of a previous haemorrhage, particularly SDHs, in infants born extremely prematurely around term-equivalent age; to examine intra- and inter-observer agreement for identification of haemorrhages; and to examine the width of the subarachnoid spaces.

Materials and methods: A total of 121 extremely premature infants had cerebral magnetic resonance imaging (MRI) performed around term-equivalent age (mean chronological age 14.7 weeks, range 10.3-24.0 weeks). There were no infants investigated for abuse in our cohort. Intracranial haemorrhages were classified as isolated germinal matrix-haemorrhages, parenchymal haemorrhages (cerebellar- and cerebral haemorrhages), or extra-axial haemorrhages (subarachnoid haemorrhages, SDHs, or epidural haemorrhages). Sinocortical width and interhemispheric distance were measured.

Results: No appreciable SDH was detected with the performed sequences. Haemorrhage/blood products related to prematurity were seen in 60 (49.5%) of the neonates. Agreement was good to very good for identification of haemorrhage. The mean sinocortical width was 3.5 mm with a standard deviation (SD) of 1.4 mm on the right side and 3.3 mm (SD 1.2 mm) on the left side. The mean interhemispheric distance was 3.1 mm (SD 1.1 mm). 61.1% of the infants had a sinocortical width > 3 mm on one or both sides.

Conclusion: Our study does not support the hypothesis that premature infants are more prone to SDH unrelated to abusive head trauma during the first 3-4 months of life. A large percentage of the ex-premature infants had prominent subarachnoid spaces.