An anoxic brain injury occurs when the brain's oxygen supply is cut off for a period of time. Many different factors can stop oxygen-carrying blood from reaching the brain, including strokes, cardiac arrest, and choking. Without sufficient oxygen, a person can slip into a coma and suffer permanent brain damage. An individual who loses consciousness for any reason should be brought to an emergency room immediately so doctors can detect underlying problems and limit the complications of an anoxic brain injury. Ongoing medical care, physical therapy, and counseling can help a patient regain the highest possible level of cognitive functioning and independence.
Blood constantly delivers a fresh supply of oxygen to the brain, rejuvenating cells and promoting regular cognitive functioning. When blood supply is depleted, brain cells begin to die within a matter of minutes. Electrical activity among neural cells is slowed and eventually stopped without new oxygen. There are no universal findings for how long it takes for extensive cell death to occur, though even two or three minutes in an anoxic state can lead to severe cognitive impairment.
An anoxic brain injury can occur when internal or external factors interrupt blood flow. A frequent cause of anoxic injuries is cardiac arrest, a condition in which the heart stops pumping blood due to a clot, congestion, or a congenital deformity. People suffering from strokes or respiratory failure are also at risk of anoxic brain injury. Choking, suffocating, near-drowning, or exposure to carbon monoxide constitute the most common external causes. Anoxic brain injury can also affect a newborn if he or she is born prematurely or with extremely low blood pressure.
The effects of an anoxic brain injury can vary widely depending on the underlying cause and the length of time the brain is without oxygen. In the short term, most cases result in comas or temporary losses of consciousness. Long-term effects can include memory loss, difficulties coordinating motor movements, and hearing and vision changes. Many people lose their ability to concentrate for extended periods of time, and some patients cannot process written or spoken information with accuracy.
In an ambulance or emergency room, immediate steps are taken to renew the brain's oxygen supply and prevent death. Recovery depends largely on the success of initial treatment measures. Once a patient is stable, specialists can conduct a series of imaging and blood tests to determine the cause and severity of a patient's injury. Lifelong rehabilitation is often necessary, including speech, occupational, and physical therapy sessions.