Hypoxic-Ischemic Encephalopathy (HIE)
Hypoxic-ischemic encephalopathy is a neurological injury caused by a lack of oxygen to the brain. The severity of the resulting injury is directly related to how long the brain goes without oxygen.
Diagnosis of HIE
Seizures or organ failure caused by HIE can occur shortly after birth; however, most cases of HIE are diagnosed when a child is between the ages of two and four. Signs that a child may have HIE include seizures, developmental delays in either motor or cognitive skills, difficulties with muscle coordination, or problems with reflex responses (e.g. gag, blink, or suck reflexes). Routine tests such as MRIs, CT scans, EEGs, or PET scans can also aid in diagnosing HIE.
Causes and Risk Factors
Asphyxia or birth hypoxia are the most common causes of HIE and usually result from complications during delivery involving the umbilical cord, the placenta, or medical malpractice. HIE caused by birth hypoxia is a leading cause of death in newborns.
Other risk factors include:
- Acute maternal hypotension
- Blood containing less oxygen due to poorly functioning lungs
- Cardiac complications
- Injury from cephalopelvic disproportion
- Injury from umbilical cord complications
- Impaired blood flow to the brain during birth
- Interruption in breathing or poor oxygen supply
- Intrapartum hemorrhage
- Prolapsed cord
- Placental abruption
- Pressure to the cranium that changes it shape, resulting in bleeding or decreased blood flow
- Ruptured vasa previa
- Stress of a long and difficult labor and delivery
- Uterine rupture
- Fetal stroke
Effects of HIE
HIE can lead to severe and permanent disabilities, including epilepsy, hearing loss, blindness, and cognitive and/or motor impairments. In addition, HIE is the cause for up to 10% of cerebral palsy diagnoses.
Prevention and Treatment
Preventing hypoxia is the single most effective way of preventing HIE. Hypoxia can be prevented by proper and accurate fetal monitoring and identifying maternal risk factors. High-risk mothers should always give birth in hospitals with neonatal intensive care units where appropriate facilities are available to treat hypoxia.
There are also some immediate post-birth treatments that can help minimize the effects of HIE. Hospitals can use a cooling blanket or cap to lower the baby’s body temperature to prevent the brain from swelling. Oxygen therapies may also be used, which include conventional and high-frequency ventilation and special breathing support measures such as nitric oxide therapy.
New England Journal of Medicine
Williams Obstetrics, 23e
T. Russell – J. Tolliver, M.D.