Cerebral hypoxia

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Central nervous system

Hypoxic encephalopathy

In mild cases, hypoxia causes only inattentiveness, poor judgment, and uncoordinated movement. Severe cases result in a state of complete unawareness and unresponsiveness (coma) -- brain stem reflexes, including response to light and the breathing reflex, stop. Only blood pressure and heart function are maintained. If this persists, brain death is inevitable.

If the lack of oxygen to the brain is limited to a very brief period of time, coma may be reversible with varying levels of return to function, depending on the extent of injury. Sometimes seizures may occur, which may be continuous with no stop between them (status epilepticus).

Cerebral hypoxia can usually be guessed from the clinical history and examination. Testing is targeted at determining the cause of the hypoxia. Tests may include:

• Magnetic resonance imaging (MRI), which provides high-quality pictures of the brain
• Electrocardiogram (EKG), a test of the electrical activity of the heart
• Echocardiogram (a test that allows the doctor to see images of the working heart)
• Blood tests, including arterial blood gases and blood sugar level
• Electroencephalogram (EEG), a test of brain waves, needed when seizures are suspected
• Evoked Potentials, a test that determines whether certain sensations like vision and touch reach the brain, causing an electric response

Review Date: 09/07/2006
Reviewed By: Kenneth Gross, M.D., Neurology, North Miami, FL. Review provided by VeriMed Healthcare Network.