The hypoxic-ischemic encephalopathy stages are three stages that describe the severity of HIE under the Sarnat staging system:
- HIE Stage 1: mild hypoxic-ischemic encephalopathy
- HIE Stage 2: moderate hypoxic-ischemic encephalopathy
- HIE Stage 3: severe hypoxic-ischemic encephalopathy
Doctors sort full-term infants into one of the stages of HIE based on the level of neonatal seizures, consciousness, muscle tone, reflexes, and how long the signs last. Severity at the diagnosis of HIE is the strongest early signal of a child’s prognosis. The diagnostic tests guide the treatment options.
While the HIE stages generally refer to the neonatal period, adults can also develop hypoxic-ischemic encephalopathy (HIE). We’ll discuss those rare cases here, as well.
If you believe a medical professional’s negligence caused your child’s brain injury, the Chicago medical malpractice attorneys can help your family seek justice. Call 312-321-1111 for a free consultation or use the buttons below to learn more.
What Is Hypoxic Ischemic Encephalopathy (HIE)?
Hypoxic Ischemic Encephalopathy (HIE) falls under neonatal encephalopathy. HIE is a serious brain injury, typically in newborns, characterized by oxygen deprivation (hypoxia) and reduced blood flow (ischemia) to the brain. The initial lack of oxygen and cerebral blood flow can lead to brain cell death, resulting in significant brain damage. Additionally, hypoxic-ischemic encephalopathy can occur before, during, or after birth. While generally caused by birth asphyxia, adults can suffer HIE when they’re deprived of oxygen, as well.
Birth Injury Hie/Hypoxic Ischemic Encephalopathy
Regardless of the stages of hypoxic-ischemic encephalopathy, the initial injury is most often associated with the term neonates. HIE occurs when a newborn’s brain is deprived of oxygen or blood flow, which affects the baby’s brain. Brain injuries caused by a lack of oxygen can occur before, during, or shortly after birth due to complications that interfere with the baby’s oxygen supply.
The severity of the birth asphyxia varies. Some infants experience temporary complications, while others develop significant long-term effects of HIE, presenting with the following symptoms: permanent cognitive impairment, developmental delays, cerebral palsy, or other lifelong disabilities.
HIE most often refers to this neonatal injury, which can occur during pregnancy, the birthing process, or shortly after birth.
Hypoxic-ischemic encephalopathy can also occur in adults when their brains don’t get enough oxygen. In either case, severity and outcomes depend on the HIE stage the patient was diagnosed with. HIE may resolve after conventional treatments, or it may cause long-term outcomes, depending on which of the three stages of HIE the patient suffers from.
HIE in Adults: Hypoxic-Ischemic (Anoxic) Brain Injury
Hypoxic-ischemic encephalopathy also affects adults. When an adult suffers a moderate to severe HIE stage, it’s generally called an anoxic or hypoxic-ischemic brain injury. Adult cases are assessed very differently from newborns, because the Sarnat staging system refers to initial injuries caused by neonatal encephalopathy or birth asphyxia. Instead, doctors evaluate how long the oxygen deprivation lasted and the patient’s response to early treatment for HIE.
Because there is no adult version of the Sarnat scale, medical professionals gauge severity and predict recovery using several tools together:
- The Glasgow Coma Scale and the duration of oxygen loss to judge acute severity
- Neuroprognostication after cardiac arrest, using clinical exam, EEG, evoked potentials, MRI, and blood biomarkers
- A recovery trajectory (coma, disorders of consciousness, then emergence) rather than fixed numbered stages
- The Cerebral Performance Category scale to grade the overall outcome
When an adult anoxic brain injury results from substandard care, such as an anesthesia error, a failure to monitor or ventilate a patient, a delayed code response, a medication error, or nursing-home neglect, it may support a medical malpractice claim. Injuries from trauma or environmental events may instead fall under catastrophic injury, and a Chicago traumatic brain injury attorney can explain which path fits the facts.
How Common Is HIE?
HIE affects about 1.5 to 2.5 per 1,000 live full-term births in developed countries like the United States. Of the infants diagnosed with HIE, 40% to 60% either die or develop a severe disability by age 2. Premature infants and babies suffering from birth asphyxia have a higher risk. Because the severity of the HIE diagnosis is the earliest signal of prognosis, the diagnostic tests and three stages of HIE shape both the treatment options and parents’ expectations from the first few hours of life.
What Causes a Child’s HIE?
Neonatal encephalopathy results when the baby’s brain doesn’t get enough oxygen and blood flow during pregnancy, the birthing process, or shortly after birth. It affects the brain’s ability to develop properly.
The most common causes of children’s HIE are generally preventable and include:
- Umbilical cord problems, such as umbilical cord prolapse, compression, or a true knot causing oxygen deprivation
- Placental dysfunction, including abruption or previa, disrupts blood flow to the baby’s brain
- Delivery complications, such as prolonged or traumatic labor causing oxygen deprivation
- Failure to closely monitor fetal distress, leading to missed heart-rate distress and delayed intervention
- Uterine rupture or maternal hemorrhage
- Infection, such as chorioamnionitis, leading to perinatal asphyxia
- Neonatal stroke or severe respiratory distress after delivery, including meconium aspiration syndrome
Sadly, for many children with HIE, careful monitoring could have prevented their initial injury, and that’s the point where medical questions become legal ones. Regardless of the stages of HIE, if you believe your child’s HIE diagnosis resulted from medical negligence, a birth injury attorney at our firm can help you get the answers and justice your family deserves.
How HIE Happens in Adults
Hypoxic brain injury in adults follows a serious loss of oxygen to the brain. Common causes include:
- Cardiac arrest or a severe cardiac arrhythmia
- Respiratory arrest or drug overdose
- Drowning or near-drowning, choking, strangulation, or hanging
- Carbon monoxide poisoning
- Severe blood loss, shock, or prolonged low blood pressure
- Anesthesia or surgical hypoxia, or a failure to monitor oxygenation or respond to a code in the hospital
HIE Stages (The Sarnat Staging System)
The hypoxic-ischemic encephalopathy stages are graded using the Sarnat staging system, a neonatal framework based on level of consciousness, muscle tone, reflexes, seizures, autonomic function, EEG results, and how long the symptoms last.
The Sarnat scale sorts newborns into three stages of HIE:
- Stage 1: mild HIE
- Stage 2: moderate HIE
- Stage 3: severe HIE
The Sarnat scale approach was first described by Sarnat and Sarnat in 1976. It has remained the clinical reference for HIE stages since. Diagnostic tests, like an EEG, can help confirm the electrical severity of the brain injury, and in moderate to severe HIE cases, an MRI shows the extent and pattern of brain damage. The table below compares the three stages of HIE at a glance.
| Clinical Feature | Stage 1 (Mild) | Stage 2 (Moderate) | Stage 3 (Severe) |
|---|---|---|---|
| Level of consciousness | Hyperalert, irritable | Lethargic, obtunded | Stupor or coma |
| Muscle tone | Normal or slightly reduced | Mild hypotonia | Flaccid |
| Reflexes | Exaggerated | Diminished | Absent or suppressed |
| Seizures | Usually none | Common (first 24 to 48 hrs) | Frequent, often treatment-resistant |
| Breathing | Normal | May be irregular | Often requires ventilation |
| Typical duration of signs | Under 24 hours | About 2 to 14 days | Hours to weeks |
| General prognosis | Usually full recovery | Guarded; varies with treatment | Grave; high risk of disability or death |
Data reflects Sarnat staging criteria (Sarnat & Sarnat, 1976), per the Nature / Pediatric Research review cited above.
Understanding your baby’s HIE stage is usually a family’s first step in questioning whether their child’s HIE was preventable. If you’re trying to find answers and financial support, our Chicago HIE birth injury lawyers can review your child’s medical records with medical experts. We offer free consultations, and clients only pay if we recover compensation on their behalf.
HIE Stage 1: Mild HIE
Severity 1 of 3 — Mild
Stage 1 HIE is the mildest form of hypoxic-ischemic encephalopathy. A newborn may be over-alert, jittery, or irritable, with mild feeding or sleep difficulty and slightly reduced muscle tone. Seizures are absent, and symptoms usually clear within 24 hours. Most infants recover fully with close monitoring.
| Sign | What Stage 1 HIE Looks Like |
|---|---|
| Alertness | Over-alert, jittery, or easily irritated |
| Muscle tone | Slightly reduced |
| Feeding & sleep | Mild difficulty with both |
| Seizures | Typically none |
| How long it lasts | Resolves within about 24 hours |
| Outlook | Most infants recover fully — the best prognosis of the three stages |
Mild signs are easy to dismiss — and easy for an Illinois hospital to miss. If your baby's oxygen loss went unrecognized at birth, we'll review the records at no cost.
HIE Stage 2: Moderate HIE
Severity 2 of 3 — Moderate
Stage 2 HIE is the moderate form. Infants are lethargic and less responsive, with low muscle tone, episodes of apnea or bradycardia, and worsening feeding difficulty. Seizures usually appear within the first 24 to 48 hours, and symptoms can last 2 to 14 days. The prognosis is guarded, but meaningful recovery is possible when therapeutic cooling begins quickly.
| Sign | What Stage 2 HIE Looks Like |
|---|---|
| Alertness | Lethargic and slow to respond |
| Muscle tone | Low (hypotonia) |
| Breathing & heart rate | Episodes of apnea and bradycardia |
| Feeding | Worsening difficulty |
| Seizures | Common in the first 24 to 48 hours |
| How long it lasts | Roughly 2 to 14 days |
| Outlook | Guarded — recovery is possible with prompt treatment, especially therapeutic cooling |
Cooling therapy works best within six hours of birth. If an Illinois hospital delayed the diagnosis or the treatment, those hours matter — and so do the records.
HIE Stage 3: Severe HIE
Severity 3 of 3 — Severe
Stage 3 HIE is the most severe form. The newborn is stuporous or comatose, with flaccid muscle tone, absent brainstem and newborn reflexes, and frequent seizures that often resist anticonvulsant medication. Many of these infants cannot breathe on their own. The prognosis is grave, which is why recognition and treatment in the first hours matter so much.
| Sign | What Stage 3 HIE Looks Like |
|---|---|
| Alertness | Stupor or coma |
| Muscle tone | Flaccid |
| Reflexes | Brainstem and neonatal reflexes absent |
| Breathing | Often cannot breathe without ventilator support |
| Seizures | Frequent and often resistant to medication |
| Outlook | Grave — high risk of lasting neurological disability or death |
Severe HIE changes a family's life permanently. If oxygen loss was preventable or the response at an Illinois hospital came too late, you deserve answers — and the cost of lifetime care deserves an accounting.
HIE Treatment: The Critical First Hours
Treatment for HIE is extremely time-sensitive. The most important intervention for cooling treatment has narrow windows.
Cooling Therapy for Hypoxic Ischaemic Encephalopathy
The primary evidence-based treatment for moderate to severe HIE is therapeutic hypothermia, which involves cooling to 33.5 to 34.5 degrees Celsius within six hours of birth and continuing for 72 hours to limit the spread of brain injury.
Cooling works alongside supportive care that stabilizes the infant and manages complications. Common supporting treatments include:
- Mechanical ventilation for infants who cannot breathe adequately
- Anticonvulsant medication to control seizures
- Nutritional support through a feeding tube or IV nutrition
- Early physical and occupational therapy to support motor development
- Continuous vital-sign and neurological monitoring in the NICU
Eligibility for cooling follows established criteria for neonatal cooling that the care team is expected to apply quickly. A related approach, targeted temperature management, is also used in adults after cardiac arrest, and a failure to consider it can be a factor in adult hypoxic brain injury cases.
Therapeutic cooling generally must begin within six hours of birth to be effective. A delay in recognizing HIE or in starting cooling can be a sign of substandard care. Contact us to have your case reviewed.
Long-Term Effects of HIE
The long-term effects of HIE track closely with the stage. Mild HIE usually resolves with little or no lasting impact, while moderate to severe HIE can cause permanent challenges that follow a child throughout life. Because outcomes vary so widely, families often need a clear picture of what may lie ahead. The most common long-term effects include:
- Cerebral palsy and other motor or coordination disorders
- Cognitive and learning disabilities
- Epilepsy and seizure disorders
- Vision and hearing impairment
- Speech and developmental delays
- Behavioral and emotional challenges
Severe HIE in particular is closely associated with cerebral palsy and with the substantial lifetime care needs that come with it. Adults who survive a hypoxic brain injury can face parallel deficits, including motor, memory, and cognitive problems, which is why the adult and infant paths both call for careful medical documentation.
Mild HIE: Learning Difficulties & Attention Issues
Children who had mild HIE most often develop typically, but some experience subtle later challenges such as mild learning difficulties or attention issues. These effects are usually manageable, and ongoing developmental follow-up helps catch and address them early.
Moderate HIE Brain Injury: Developmental Delays, Speech, Learning & Fine Motor Coordination Issues
Moderate HIE can leave a range of developmental effects, including delays in reaching milestones, speech and language difficulties, learning disabilities, and problems with fine motor coordination. Early intervention therapy often makes a meaningful difference in how these children progress.
Severe HIE Brain Damage: Cerebral Palsy, Intellectual Disability, Epilepsy, Feeding Difficulties, Microcephaly, Vision & Hearing Loss
Severe HIE brain damage is associated with the most significant lasting conditions, including cerebral palsy, intellectual disability, epilepsy, feeding difficulties, microcephaly, and vision or hearing loss. Related motor conditions such as spastic hemiplegia and injuries in the traumatic brain injury category can carry similarly high lifetime care costs. National cerebral palsy data from the CDC illustrate the scope of support these children often require.
When HIE Is Caused by Medical Negligence
When an adult or child’s HIE results from a medical professional’s failure to meet the Illinois standard of care, it may be medical malpractice. For newborn babies with HIE, this generally means parents will pursue a birth injury claim for HIE.
For adults, particularly those who have developed more severe HIE stages, this often results from surgical errors, anesthesia errors, nursing home negligence, or general hospital malpractice. Regardless, just like babies with HIE, the central factor is whether the oxygen loss that led to the HIE diagnosis was preventable.
Common examples of medical negligence resulting in moderate or severe HIE stages include:
- Failure to monitor or respond to fetal distress, or ensure a hospitalized adult gets enough oxygen
- Delay in ordering a C-section
- Delayed recognition of HIE symptoms or delays in starting the cooling period
- Improper resuscitation or post-event NICU or ICU management
Proving one of these cases takes complete medical records, expert review, and a clear link between the error and the harm. Our firm can explain who can file a claim, what evidence is needed, and the compensation available to families. Moderate or severe HIE stages reflect a lifetime of care costs and, in the most tragic outcomes, may proceed as a wrongful death claim.
You can also read our guide on how to sue an Illinois hospital for negligence or review our medical malpractice verdicts and settlements.
Birth Injury Support For Families Affected By An HIE Diagnosis in Cook County
We represent families affected by hypoxic-ischemic encephalopathy at every level across Cook County as well as the surrounding collar counties of DuPage, Lake, Will, Kane, and McHenry. Our attorneys understand both the local medical and legal landscape and can help families weigh their legal options for seeking justice.
Locally, birth injury and medical malpractice lawsuits are filed in the Circuit Court of Cook County, in the Law Division at the Richard J. Daley Center. The region is also served by advanced neonatal intensive care units, including those at Ann & Robert H. Lurie Children’s Hospital, Northwestern Prentice Women’s Hospital, and University of Chicago Comer Children’s Hospital, where infants with the more serious hypoxic-ischemic encephalopathy stages often receive care.
If your child was diagnosed with hypoxic-ischemic encephalopathy or if you have questions about legal options based on your child’s specific hypoxic-ischemic encephalopathy stage, you can schedule a free consultation or call 312-321-1111.
FAQs About HIE Stages
What is the life expectancy of a baby with stage 3 HIE?
Life expectancy for babies with HIE at the third stage (severe) depends on the extent of brain damage and how the infant responds to the treatment for HIE. Moderate to severe HIE carries the highest risk of mortality and profound disability among the three stages of HIE. Outcomes improve when therapeutic hypothermia begins within six hours after birth, and each child’s recovery is best discussed with a treating healthcare professional.
Is HIE considered a disability?
A diagnosis of HIE is just that: a medical diagnosis. However, the lasting effects of an HIE diagnosis are recognized disabilities. Cerebral palsy, epilepsy, and cognitive impairment can all qualify a child for support services and benefits. Once the parent gets the HIE diagnosed, the following support largely depends on the severity of the injury and how their child’s HIE affects daily life.
Can a baby fully recover from HIE?
Whether or not babies with HIE can fully recover depends on the severity. Most babies with mild hypoxic-ischemic encephalopathy (HIE) recover completely. Some infants with moderate HIE recover significantly when treatment begins quickly. Full recovery outcomes start diminishing with moderately severe HIE. Moderate or severe HIE, particularly stage 3 HIE (severe), often results in permanent disability. Generally, the first stages of HIE have better outcomes.
What is considered severe HIE?
Severe HIE is Stage 3 on the Sarnat scale. Stage 3 severe HIE is marked by stupor or coma, flaccid muscle tone, and absent reflexes. Additionally, patients who survive severe hie develop frequent and medication-resistant seizures and are unable to breathe independently. Stage 3 severe HIE has the most serious complications and carries the highest risk of long-term disability or death.
Can adults recover from hypoxic (anoxic) brain injury?
Whether or not an adult can recover from a hypoxic-ischemic brain injury depends on how long the brain cells were deprived of oxygen, the area of the brain affected, the underlying cause, and the response to early treatment. Outcomes range from full recovery to long-term disability. Adults are assessed with tools other than the neonatal Sarnat stages, and targeted cooling treatment after cardiorespiratory failure or cardiac arrest can improve results in moderately “mild” cases.
Questions About the Stages of HIE? Contact Our Chicago Lawyers
If you believe negligence caused your child’s injury, or that a negligent healthcare professional contributed to an adult hypoxic brain injury, Curcio & Casciato can explain your legal options. We review the medical records behind the hypoxic-ischemic encephalopathy stages with medical experts, and consultations are always free. Call 312-321-1111 or request a free consultation today.
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