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Neuroradiology Case of the Week

Case 201

Peter H. Takeyama, MD and Per-Lennart Westesson, MD, PhD, DDS

Clinical Presentation: Patient is a 4-day-old term infant who presented at birth with hypoxia, cyanosis, and low Apgar scores. Seizure activity was noted on EEG with right frontotemporal and centroparietal origin with rapid evolution to involve the left hemisphere.

Radiological Findings:

Diagnosis: Hypoxic ischemic encephalopathy

Discussion: Hypoxic ischemic encephalopathy (HIE) is due to prolonged decreased perfusion and oxygenation of the brain; causes include neonatal anoxia, hypoglycemia, suffocation, cardiac arrest or child abuse.
     Brain hypoxia and ischemia from systemic hypoxemia and decreased cerebral blood flow is initially thought to cause neuronal damage at the cellular level due to energy failure. A second phase of neuronal damage by reperfusion injury is thought to determine the ultimate extent of injury.
     Incidence of HIE has been reported to be around 2-4 cases in 1000 births. With severe HIE, mortality can be as high as 50%, with half of the infants dying within the first month of life. Among those infants who survive HIE, they go on to suffer from mental retardation, epilepsy, and cerebral palsy.
     Often times, CT or MRI may show no significant findings. Diffusion weighted imaging (DWI) often show acute or subacute ischemic lesions in the regions of the corpus callosum, and along the pyramidal tract in the internal capsules and the brain stem. This is presumably due to cytotoxic edema of the glial cells, axons and myelin sheath.

References:

1. Moritani T, Ekholm S, Westesson PL. Diffusion-weighted MR Imaging of the Brain. Springer-Verlag Berlin Heidelberg, 2004.
2. Barkovich J. Pediatric Neuroimaging. Lippincott Williams & Wilkins, Philadelphia, PA, 2005
3. Raju TNK. Hypoxic-Ischemic Encephalopathy. http://www.emedicine.com/ped/topic149.htm