Cerebral venous congestion following closed head injury in a child.

In pediatric patients with head injury, progressive hemispheric low density (HLD) on CT is a specific phenomenon although the underlying mechanism remains controversial. We used CT, MRI, diffusion weighted imaging (DWI), and perfusion weighted imaging (PWI) studies to identify pathophysiological patterns in a child. A 6-year-old boy sustained a left temporal head injury in a car accident. Although the initial CT was normal, serial CT demonstrated progressive left HLD; an extensive heterogeneous high-intensity lesion was noted on fluid-attenuated imaging recovery (FLAIR) and DWI studies. On PWI, the regional cerebral blood volume was increased and the mean transit time was markedly prolonged. After the conservative treatment, despite the widespread abnormal imaging on CT and DWI, the final brain damage located in isolated left temporal cortical brain damage. The lesion coincided with the area on PWI where increased rCBV and MTT prolongation were noted. Based on these findings, we posit that the extensive but reversible brain changes seen on neuroimaging studies were the result of venous congestion. Our result stresses the importance of functional neuroimaging such as DWI and PWI in order to elucidate the pathophysiology of HLD.