Hypoxic Ischaemic Encephalopathy: Assessment of Severity by MR Imaging

Abstract

CONTEXTPerinatal asphyxia happens in 2 to 10 per 1000 newborns that are born at term, and more for those that are born prematurely and making one of the leading cause of death worldwide. AIMTo study the pattern of involvement of brain in HIE influenced by nature of insult and to assess the severity of brain injury by MR imaging and correlate with clinical staging (Sarnat criteria). METHODOLOGY43 cases with history of perinatal asphyxia were included in this study by applying the inclusion criteria and exclusion criteria. Signal changes in T1 and T2 weighted images and diffusion weighted were assessed and recorded. RESULTS AND INTERPRETATIONSAfter MR imaging, most of the Sarnat Stage I and II patients were mild and stage III patients were severe. Of the all clinically diagnosed having HIE, 25.6% cases were normal. Patients with clinically mild hypotension >1/2 (54.2%) of them were found to be normal after imaging. Patients with clinically moderate hypotension, 20% were normal at MRI; and >1/2 (52%) of them showed only mild changes and 12% showed severe involvement. Term babies with mild encephalopathy shows more involvement of periventricular white matter than subcortical white matter. Clinically severe encephalopathy correlates with abnormal basal ganglia -thalamic lesions in term babies and germinal matrix haemorrhage in preterm babies. Clinically moderate encephalopathy correlates with signal changes in posterior limb of internal capsule and perirolandic white matter. Prematurity increases the susceptibility of brain to changes caused by hypoxia. No significant association noted between sex and birth weight with abnormal MR imaging findings. The low Apgar score shows significant association with severity of brain involvement. Seizure and its onset also appears to be a deciding parameter in severity of brain injury.