Hypoxic/Anoxic Brain Injury (HAI)



The brain requires a constant flow of oxygen to function normally. A hypoxic-anoxic injury, also known as HAI, occurs when that flow is disrupted, essentially starving the brain and preventing it from performing vital biochemical processes. Hypoxic refers to a partial lack of oxygen; anoxic means a total lack. In general, the more complete the deprivation, the more severe the harm to the brain and the greater the consequences.


The diminished oxygen supply can cause serious impairments in cognitive skills, as well as in physical, psychological and other functions. Recovery can occur in many cases, but it depends largely on the parts of the brain affected, and its pace and extent are unpredictable.


As a result, HAI can have a catastrophic impact on the lives not only of those injured but their families, friends and caregivers as well. Treatment can be costly and complicated, especially because HAI patients frequently need substantial medical and rehabilitative help and may suffer from significant long-term disabilities. A shortage of easy-to-understand, accessible information about HAI can make the situation even more stressful for affected individuals and their families.


HAI is generally marked by an initial loss of consciousness or coma, a condition which looks like sleep but from which a person cannot be awakened. The period of unconsciousness, whether short or long, might be followed by a persistent vegetative state, in which a person is neither comatose nor responsive to external stimuli. This state is frequently referred to as “wakeful unresponsiveness.”


Even when a person has fully recovered consciousness, he or she might suffer from a long list of symptoms. In many ways, these symptoms are similar to those commonly seen after a blow to the head. The effects can vary widely depending upon the part of the brain that has been injured and the extent of the damage.


Some of the major cognitive (thought) problems are:


  • Short-term memory loss. This is the most common cognitive symptom, especially among those who have HII. The reason is that the part of the brain that is believed to be responsible for learning new information, called the hippocampus, has neurons that are highly sensitive to oxygen deprivation.

  • Decline in executive functions. Disruption of such critical tasks as reasoning, making judgments, and synthesizing information. This can lead to impulsive behavior, poor decision-making, inability to direct, divide, or switch attention.

  • Difficulty with words, also known as anomia. These linguistic problems include not being able to remember the right word, selecting the wrong word, confusing similar words, not understanding commonly used words, and so on.

  • Visual disturbances. Difficulty processing visual information can occur in some cases. One rare disorder is called cortical blindness, in which the area of the brain responsible for vision becomes disconnected from the rest of the brain. Because the brain cannot tell that this part is damaged, people may appear to act as though they can see even though they display no ability to identify or recognize objects, shapes or colors.


Some common physical deficits are:


  • Ataxia, or a lack of coordination. This often expresses itself as a sort of bobbing or weaving, similar to what is seen in people who are drunk.

  • Apraxia, or an inability to execute a familiar sequence of physical movements such as brushing teeth, combing hair, using eating utensils, etc.

  • Spasticity, rigidity and myoclonus, disorders which can include a tendency toward jerky motions, trembling of the extremities, or other abnormal movements.

  • Quadriparesis, a weakness of the arms and legs.


Other symptoms can include: hallucinations and delusions; increased agitation and confusion; depression and other mood disorders; personality changes, such as irritability and a reduced threshold for frustration; and an inability to focus or concentrate.