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Anoxic Brain Damage by Nathalie Smith, MSN, RN

Definition

Anoxic brain damage is injury to the brain due to a lack of oxygen. Brain cells without oxygen will begin to die after about four minutes.

Progression of Anoxic Brain Damage

Causes

Oxygen is carried to the brain in the blood. Anoxic brain damage may occur if:

Blood flow to the brain is blocked or slowed. This can happen with:
- Blood clot or stroke—blood flow to an area of the brain is blocked
- Shock and heart problems, like heart attack—blood is not pumped effectively enough to reach the brain
The blood flow is normal but the blood is not carrying enough oxygen. This may happen because of medical conditions like:
- Lung disease—oxygen has trouble passing from the lungs to the blood
- Chronic anemia—a condition that results in low red blood cells, these cells carry the oxygen in blood
You have exposure to certain poisons or other toxins. For example, carbon monoxide poisoning keeps your blood from picking up oxygen.
There is a lack of oxygen in the air. This can occur at high altitudes.

Risk Factors

The following accidents and health problems increase your risk of anoxic brain damage:

Cardiac arrest
Choking
Suffocation
Near-drowning
Electrical shock
Malfunctioning gas appliances that produce carbon monoxide
Heart attack
Heart arrhythmia (abnormal heart beats)
Stroke
Brain tumors
Drug use

Symptoms

Severe damage may lead to a coma or a vegetative state. Mild to moderate anoxic brain damage may cause:

Headache
Confusion
Decreased concentration and attention span
Mood swings and/or personality change
Intermittent loss of consciousness
Seizures
Parkinson’s like syndrome
Abnormal muscle jerks with movements

Rarely there may be a decline in brain function a few days or weeks after the event occurred. This is caused by delayed injury in the brain. Symptoms may then improve gradually over time.

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be done. You may need to see a doctor who specializes in brain problems.

These tests may be ordered to learn the extent of the brain damage and the part of the brain that is involved:

Head CT scan —a type of x-ray that uses a computer to make detailed images of the brain
MRI scan —a test that uses magnetic waves to make pictures of structures inside the head
Electroencephalogram (EEG) —a test that measures the electrical activity generated by the brain
SPECT scans—a type of CT scan that examines areas of the brain for blood flow and metabolism.
Evoked potential tests—tests used to evaluate the visual , auditory, and sensory pathways

Treatment

Initial Treatment

Treatment of anoxic brain damage will depend on the cause. Some treatment options include:

Medication to:
- Slow down brain activity and decrease need for oxygen
- Reduce the swelling from injured brain tissue—swelling can cause further damage
Oxygen therapy—to increase the amount of oxygen in the blood
Efforts to cool the brain—to help limit brain damage.
Hyperbaric oxygen treatment —may be used with carbon monoxide poisoning

Rehabilitation

Recovery from brain damage can be uncertain. It will also take time. Your chance for recovery depends on how long and how severely you were deprived of oxygen. Many people with mild brain damage can usually recover most of the lost functions.

During rehabilitation, you and your family will work with:

Physical therapist—to retrain motor skills, such as walking
Occupational therapist—to improve daily skills, such as dressing and going to the bathroom
Speech therapist—to work on language problems
Neuropsychologist—for behavior and emotional issues related to the injury

Recovery can take months, or even years. In many cases, full recovery is never achieved but some can successfully learn to live with any remaining disabilities. In general, the sooner rehabilitation starts, the better the outcome.

Medication

Your doctor may have you take the following medicines:

Anti-epileptic medicines—to treat ongoing seizures
Clonazepam (eg, Klonopin)—to treat muscle jerks

Prevention

To reduce the risk of anoxic brain damage:

Chew your food carefully.
Learn to swim.
Carefully supervise young children around water.
Stay clear of high voltage electrical sources (including exposure to lightning).
Avoid chemical toxins and illicit drugs.
Check gas burning appliances for carbon monoxide production and install carbon monoxide detectors.

RESOURCES:

American Brain Injury Society http://www.biausa.org/
National Institute of Neurological Disorders and Stroke http://www.ninds.nih.gov/

CANADIAN RESOURCES:

Brain Injury Association of Alberta http://www.biaa.ca/
Ontario Brain Injury Association http://www.obia.ca/index.php/

References:

Albano C, Comandante L, Nolan S. Innovations in the management of cerebral injury. Crit Care Nurs Q . 2005;28:135-149.
Biagas K. Hypoxic-ischemic brain injury: advancements in the understanding of mechanisms and potential avenues for therapy. Curr Opin Pediatr . 1999;11:223-228.
Fauci AS, Braunwald E, Kasper DL, et al. Harrison's Principles of Internal Medicine. 17th ed. New York, NY: McGraw Hill; 2008: chap 269.
Hopkins R, Haaland K. Neuropsychological and neuropathological effects of anoxic or ischemic induced brain injury. J Int Neuropsychol Soc . 2004;10:957-961.
Juul S. Erythropoietin in the central nervous system, and its use to prevent hypoxic-ischemic brain damage. Acta Paediatr Suppl . 2002;91:36-42.
Ramani R. Hypothermia for brain protection and resuscitation. Current Opinions in Anesthesiology . 2006;19:487-491.
Shprecher D, Mehta L. The syndrome of delayed post-hypoxic leukoencephalopathy. Neuro Rehabilitation. 2010:26(1): 65-72.

Last reviewed September 2012 by Rimas Lukas, MD

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