Anoxic brain injury, also called anoxic encephalopathy or hypoxic-ischemic brain injury, is a life threatening condition resulting from a complete lack of oxygen to the brain.
Anoxic brain injury (ABI), also called hypoxic-ischemic brain injury or anoxic encephalopathy, happens when your brain does not get oxygen for a period of time long enough that brain cells die. This is a serious, often life threatening condition that frequently causes permanent brain injury.
It’s difficult to know how many people experience ABI since so many different medical events may cause it. Many people who have ABI also experience coma. Of those individuals,
Read on to learn more about anoxic brain injury, how it’s treated, and what the outlook is for people who experience it.
Anoxia is the medical term for a loss of oxygen. ABI happens when the brain does not have oxygen for a period of time that is long enough to cause injury to the brain but not long enough to cause immediate death.
There are short-term as well as long-term symptoms of ABI. Immediately during and after an event that causes ABI, symptoms may include:
- loss of consciousness (possible coma immediately after the injury)
- turing blue
- seizures
- confusion
- headache
- death
Some of the long-term symptoms of ABI may resolve over time, or they may be permanent.
Long-term symptoms may include:
- unresponsive wakefulness syndrome (persistent vegetative state)
- fatigue
- low blood pressure
- cognitive changes, such as memory loss, impaired judgement, and attention difficulties
- changes in motor function (fine motor skills like holding a fork, writing, etc., and gross motor skills like balance and walking)
- paralysis or paresis
- tremors
- seizures
- spasticity (tight muscles, limited movement)
- blindness (cortical blindness)
- speech impairments
- emotional changes like irritability, frustration, depression
Anything that prevents your brain from getting oxygen can cause ABI. The most common cause is a cardiovascular event like a heart attack or stroke. Of the many events that may cause ABI, here are some of the most common causes:
- strangulation, choking, or suffocation
- near-drowning
- severe hypotension (very low blood pressure)
- fires (smoke inhalation)
- carbon monoxide poisoning
- traumatic vascular injury (injury to blood vessels through trauma like stabbing, accidents, and falls)
- drug overdose
- acute lung injury (ALI) conditions that affect the lungs’ ability to accept oxygen
- severe anemia
ABI that happens to a baby before or during delivery is called hypoxic-ischemic encephalopathy (HIE). ABI in infants may be caused by:
- Maternal factors such as:
- preeclampsia
- chorioamnionitis
- bleeding during pregnancy and delivery
- infections
- thyroid disease
- fetal factors, such as:
- anemia
- congenital heart disease
- genetic conditions
- metabolic diseases
- shoulder dystocia
- prolonged or difficult labor
- obstetric emergencies
- placental difficulties, including:
- abruption
- abnormalities
- umbilical cord compression
- preterm labor
- premature delivery
It’s crucial to diagnose ABI as soon as possible after it has occurred to ensure the brain receives adequate oxygen again, to rule out other potential causes of the brain injury, and to document the extent of oxygen loss to the brain. Prompt diagnosis also helps prevent further brain injury.
The
- Medical history: Collecting past medical history and a complete account of the event that led to anoxia from those who witnessed it, provided care, and others, helped inform the care.
- Physical and neurological exams: These exams assess various aspects, including consciousness, reflexes, pupil reaction, motor responses, and other signs and functions.
- Blood tests: These tests assess various factors, including oxygen levels, infections, metabolic conditions, and the presence of drugs in the blood.
- Imaging tests: Imaging tests like CT scans to check for bleeding in the brain or additional brain trauma, and MRI to check for brain injury, help confirm the diagnosis, and help determine treatment options and outlook.
- Electroencephalography (EEG): This test measures brain waves and helps identify seizure activity and other abnormal brain wave patterns.
- Evoked potential testing: This test is used to assess an individual’s level of consciousness.
The
Treatment options may include:
- Immediate resuscitation: Resuscitation is CPR or advanced life support, and the goal is to restore oxygen to the brain, which is the most important immediate treatment for individuals who have had ABI.
- Correction of underlying causes: This treatment is designed to address the underlying cause of the oxygen loss, for example, treatment may involve treating cardiac arrest, clearing airways, reversing drug overdoses, or treating infections.
- Targeted temperature management (therapeutic hypothermia): Mild cooling (32–36°C) of the body for 24–48 hours after cardiac arrest can reduce brain injury. Protocols and recommendations may evolve as new discoveries are made in research. Seizure management: Antiepileptic medications if seizures or myoclonus develop
- Supportive care: This type of treatment involves other therapies, such as:
- oxygen therapy
- hemodynamic support
- prevention of secondary complications (aspiration, blood clots, skin breakdown)
- Rehabilitation: Once an individual’s condition becomes stable, early rehabilitation (physical, occupational, speech therapy, for example) is key to maximizing function and recovery.
- Medications: They are administered for various reasons. One of the primary benefits is to help
stop shivering during hypothermia management.
Major complications of ABI include:
- coma or persistent vegetative state
- seizures
- movement disorders (myoclonus)
- cognitive changes, from mild memory loss to severe deficits
- behavioral and emotional disturbances
- permanent motor changes (paralysis, spasticity)
- increased risk of infections
- immobility-related health conditions
- death
Individuals who have ABI may experience complications related to their brain injury or as side effects of therapies.
The outlook for individuals with ABI can vary widely. Many factors will determine their outlook. Things like the initial event that caused the injury, the timing and severity of that event, and how quickly medical care started.
Recovery from ABI may range from full recovery, mild changes and conditions, to permanent disability or death. Much of an individual’s outlook is determined by how long oxygen has not been reaching their brain.
Anoxia means total loss of oxygen to the brain, while hypoxia means a reduction of oxygen (rather than a complete loss). The term “anoxic brain injury” is typically used to describe or diagnose severe cases of brain injury from a complete lack of oxygen.
Without oxygen, brain cell injury begins very quickly – within minutes. Brain cell death becomes significant within 4 to 5 minutes if oxygen is not restored.
Some individuals who have mild brain injury may recover partially, but severe brain injuries often cause permanent brain and physical changes, and some people who have ABI may die.
Anoxic brain injury is a serious condition caused by a lack of oxygen to the brain. Typically, people who experience it need emergency medical care to restore oxygen to their brain as soon as possible.
The outcome may be quite serious, and people may experience permanent disability or, in many cases, death.
Rapid resuscitation that restores oxygen to the brain, combined with specialized care that includes targeted temperature management, can significantly improve the likelihood of neurological recovery.
Early care, accurate diagnosis, and support for patients and families are essential to optimize long-term outcomes.