A proposed magnetic resonance imaging grading system for the spectrum of central neonatal parasagittal hypoxic-ischaemic brain injury.

Aim: To describe the spectrum of parasagittal injury on MRI studies performed on children following severe perinatal term hypoxia-ischaemia, using a novel MRI grading system, and propose a new central pattern correlated with neuropathologic features.

Methods: MR scans of 297 patients with perinatal term hypoxia-ischaemia were evaluated for typical patterns of brain injury. A total of 83 patients that demonstrated the central/basal ganglia-thalamus and perirolandic pattern of injury were categorised according to the degree of severity. The perirolandic injury was graded by the degree of interhemispheric widening, paracentral lobule involvement and perirolandic cortex destruction leading to a tiered categorisation. Of these 83 patients, 19 had the most severe subtype of injury. A detailed analysis of the clinical data of a subset of 11 of these 19 patients was conducted.

Results: We demonstrated the mild subtype in 21/83(25%), the moderate subtype in 22/83(27%) and the severe subtype in 21/83(25%). A fourth pattern was identified in 19/83(23%) patients with a diamond-shaped expansion of the interhemispheric fissure, concomitant thalamic, putaminal, hippocampal and other smaller substrate involvement indicative of the most destructive subtype.

Conclusions: We propose a new MR grading system of injury at the parasagittal perirolandic region related to severe, sustained central perinatal term hypoxia-ischaemia. We also introduce a previously undescribed pattern of injury, the most severe form of this spectrum, seen especially after prolongation of the second stage of labour. This constellation of high metabolic substrate, targeted tissue destruction is consistently demonstrated by MRI, termed the massive paramedian injury pattern.