Subdural hygroma
Subdural hygroma is a subdural fluid collection
see Traumatic subdural hygroma.
Kim et al. suggested that increased cerebrospinal space and cerebrospinal fluid pressure may result in compensatory enlargement of head circumference only in the infant period, and the subdural hygroma thickness decreases with age during the infant and toddler phases 1).
1)
Kim MJ, Choi DH, Yoo CJ, Lim YC, Yoon SH. Relationships between Head Circumference Percentile, Lumbar Puncture Pressure, and Cerebrospinal Fluid Space in Young Children: Increased Cerebrospinal Space and Pressure May Result in Compensatory Enlargement of Head Circumference Only in the Infant Period. Pediatr Neurosurg. 2019 Oct 10:1-8. doi: 10.1159/000503113. [Epub ahead of print] PubMed PMID: 31600754.