Clinical Manifestations of Hypoxic–Ischemic Encephalopathy

Hypoxic–ischemic encephalopathy (HIE) is a common cause of neonatal encephalopathy and requires careful and prompt diagnosis in order to initiate therapeutic hypothermia, a time-sensitive neuroprotective treatment. The clinical presentation is key in distinguishing HIE from other causes of neonatal encephalopathy and includes assessment of Apgar scores, physiologic markers of acute hypoxia such as the initial blood gas, the presence of an acute hypoxic–ischemic event, and exam findings consistent with a moderate or severe degree of encephalopathy. Specific eligibility criteria exist for each of these factors and are standardized across centers. Neurodiagnostic tools important for the evaluation and management of HIE include the electroencephalogram (EEG) and magnetic resonance imaging (MRI). EEG can help assess the degree of encephalopathy, provide early prognostic information, and detect subclinical seizures. The MRI is the gold standard imaging test to evaluate the location and degree of HIE injury and provide the most accurate information about long-term outcome.