Cerebral hypoxia Health Article

Definition

Cerebral hypoxia technically means a lack of oxygen supply to the outer part of the brain, an area called the cerebral hemisphere. However, the term is more typically used to refer to a lack of oxygen supply to the entire brain.

Alternative Names

Hypoxic encephalopathy

Causes, incidence, and risk factors

There are many causes of cerebral hypoxia. These include, but are not limited to:

• Asphyxiation caused by smoke inhalation
• Carbon monoxide poisoning
• Cardiac arrest (when the heart stops pumping)
• Choking
• Complications of general anesthesia
• Compression of the windpipe (trachea)
• Diseases that cause a loss of movement (paralysis) of the breathing muscles
• Drowning
• Drug overdose
• High altitudes
• Injuries before, during, or soon after, birth (See: Cerebral palsy)
• Strangulation
• Stroke
• Very low blood pressure

Brain cells are extremely sensitive to oxygen deprivation. Some brain cells actually start dying less than 5 minutes after their oxygen supply disappears. As a result, brain hypoxia can rapidly cause death or severe brain damage.

Symptoms

Symptoms of mild cerebral hypoxia include:

• Change in attention (inattentiveness)
• Poor judgment
• Uncoordinated movement

Symptoms of severe cerebral hypoxia include:

• Complete unawareness and unresponsiveness (coma)
• No breathing
• No response to light

If only blood pressure and heart function remain, then the brain may actually be completely dead.

Signs and tests

Cerebral hypoxia can usually be diagnosed based on the person's medical history and a physical exam. Tests are done to determine the cause of the hypoxia, and may include:

• Blood work, including arterial blood gases and blood sugar level
• Echocardiogram
• Electrocardiogram (ECG), a measurement of the heart's electrical activity
• Electroencephalogram (EEG), a test of brain waves that can identify seizures and show how well brain cells work
• Evoked potentials, a test that determines whether certain sensations such as vision and touch reach the brain
• Magnetic resonance imaging (MRI)