Abstract

Neonatal encephalopathy (NE), also known as neonatal hypoxic-ischemic encephalopathy (neonatal HIE or NHIE), is defined by signs and symptoms of abnormal neurological function in the first few days of life in an infant born at term. In this condition there is difficulty initiating and maintaining respirations, a subnormal level of consciousness, and associated depression of tone, reflexes, and possibly seizures. Encephalopathy is a nonspecific response of the brain to injury which may occur via multiple methods, but is commonly caused by birth asphyxia.

Signs and symptoms

In neonates born at or beyond 35 weeks, neonatal encephalopathy may present itself as the following symptoms:

- Reduced level of consciousness

- Seizures (which peak at 48 hours)

- Difficulty initiating and maintaining respiration

- Depression of tone and reflexes

Diagnosis

Cord blood gas analysis can be used to determine if there is perinatal hypoxia/asphyxia, which are potential causes of hypoxic-ischemic encephalopathy or cerebral palsy, and give insight into causes of intrapartum fetal distress. Cord blood gas analysis is indicated for high-risk pregnancies, in cases where C-sections occurred due to fetal compromise, if there were abnormal fetal heart rate patterns, Apgar scores of 3 or lower, intrapartum fever, or multifetal gestation.

Evidence of brain injury related to the hypoxic-ischemic events that cause neonatal encephalopathy can be seen with brain MRIs, CTs, magnetic resonance spectroscopy imaging or ultrasounds.

Neonatal encephalopathy may be assessed using Sarnat staging.

Treatment

In the past, treatment options were limited to supportive medical therapy. Nowadays neonatal encephalopathy is treated using hypothermia therapy.

Epidemiology

Overall, the relative incidence of neonatal encephalopathy is estimated to be between 2 and 9 per 1000 term births. 40% to 60% of affected infants die by 2 years old or have severe disabilities. In 2013 it was estimated to have resulted in 644,000 deaths down from 874,000 deaths in 1990.

Prognosis

HIE is a major predictor of neurodevelopmental disability in term infants. 25 percent have permanent neurological deficits.

It can result in developmental delay or periventricular leukomalacia.