Cerebral Hypoxia (Brain Hypoxia) Causes, Symptoms, Diagnosis, Treatment, Prevention

Cerebral Hypoxia (Brain Hypoxia) Causes, Symptoms, Diagnosis, Treatment, Prevention

Cerebral Hypoxia (Brain Hypoxia) definition

Cerebral hypoxia refers to a condition in which there is a decrease of oxygen supply to the brain even though there is adequate blood flow. Drowning, strangling, choking, suffocation, cardiac arrest, head trauma, carbon monoxide poisoning, and complications of general anesthesia can create conditions that can lead to cerebral hypoxia. Symptoms of mild cerebral hypoxia include inattentiveness, poor judgment, memory loss, and a decrease in motor coordination. Brain cells are extremely sensitive to oxygen deprivation and can begin to die within five minutes after oxygen supply has been cut off. When hypoxia lasts for longer periods of time, it can cause coma, seizures, and even brain death. In brain death, there is no measurable activity in the brain, although cardiovascular function is preserved. Life support is required for respiration.

Read more: Charcot-Marie-Tooth Disease: Causes, Symptoms, Types, Diagnosis, Treatment

What Causes Cerebral Hypoxia (Brain Hypoxia)

In cerebral hypoxia, sometimes only the oxygen supply is interrupted. This can be caused by:

  • Breathing in smoke (smoke inhalation), such as during a fire
  • Carbon monoxide poisoning
  • Choking
  • Diseases that prevent movement (paralysis) of the breathing muscles, such as amyotrophic lateral sclerosis (ALS)
  • High altitudes
  • Pressure on (compression) the windpipe (trachea)
  • Strangulation

In other cases, both oxygen and nutrient supply are stopped, caused by:

  • Cardiac arrest (when the heart stops pumping)
  • Cardiac arrhythmia
  • Complications of general anesthesia
  • Drowning
  • Drug overdose
  • Injuries to a newborn that occurred before, during, or soon after birth
  • Stroke
  • Very low blood pressure

Sometimes diseases like asthma or anemia can limit the amount of oxygen that reaches the brain, causing mild to moderate cerebral hypoxia. External factors like deep-sea diving, flying in an unpressurized plane, choking, strangulation or drowning can all cause moderate to severe cerebral hypoxia.

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

What Causes Cerebral Hypoxia (Brain Hypoxia) in Babies?

There are several causes for cerebral hypoxia or a lack of oxygen to an infant during delivery or shortly after birth. Some of these causes are:
  • The mother's blood pressure drops
  • The umbilical cord is compressed
  • The baby's position in the womb is abnormal
  • Problems with the placenta
  • Rupture of the uterus
  • Medical negligence or improper medical care
When something happens during delivery to cause cerebral hypoxia, it’s usually indicated as distress on a fetal heart monitor reading. If the medical team assisting in your delivery doesn’t respond properly or quickly enough to correct the situation and restore oxygen to your baby, that can be considered medical negligence.

Symptoms of Cerebral Hypoxia (Brain Hypoxia)

Unlike with the more traumatic, severe forms of cerebral hypoxia, the milder forms may be difficult to spot. Symptoms include a loss of motor skills, a lightheaded feeling, fainting, increased heart rate, and/or seizures.

Increased heart rate may exhaust the heart as it struggles to pump oxygen through the body to the brain. The heart may stop beating, requiring CPR, defibrillation or an injection of drugs like epinephrine (used by people with severe food or bee allergies) to get the heart pumping again.

Very severe cases of prolonged hypoxia can lead to coma and even brain death. During and after severe oxygen deprivation, cells in the brain may die due to an increase in acidity in the brain tissue. This increase in acidity is called “acidosis.”

Even after the return of oxygen to the brain, a problem called “reperfusion injury” may damage the brain. While deprived of oxygen, brain cells build up oxidizing free radicals that will then be let loose into the brain and nerves after the oxygen supply returns. Reperfusion injury is generally treated with therapeutic hypothermia, where a patient's body temperature is lowered to prevent cells and membranes from being attacked by the free radicals.

How Is Cerebral Hypoxia (Brain Hypoxia) Diagnosed?

Your doctor can diagnose Cerebral Hypoxia by examining your symptoms, recent activities, and medical history. A physical exam and tests are usually part of the process. Tests may include:
  • Blood tests that show the amount of oxygen in your blood
  • Magnetic resonance imaging (MRI) scan to show detailed images of your head
  • Computed tomography (CT) scan for a three-dimensional image of your head
  • Tests that take a picture of your heart (echocardiogram) and measure its electrical activity (electrocardiogram)
  • Electroencephalogram (EEG) to examine the electrical activity of your brain and pinpoint seizures
  • Brainstem auditory evoked response (BAER) to see how your brain reacts to sounds

Treatment for Cerebral Hypoxia (Brain Hypoxia)

Cerebral hypoxia is an emergency condition that need to be treated right away. The sooner the oxygen supply is restored to the brain, the lower the risk of severe brain damage and death.

Treatment depends on the cause of the hypoxia. Basic life support is most important. Treatment involves:

  • Breathing assistance (mechanical ventilation) and oxygen
  • Controlling the heart rate and rhythm
  • Fluids, blood products, or medications to raise blood pressure if it is low
  • Medications including phenytoin, phenobarbital, valproic acid, or general anesthetics to calm seizures
Sometimes a person with cerebral hypoxia is cooled to slow down the activity of the brain cells and decrease their need for oxygen. However, the benefit of this treatment has not been firmly established.

Can You Prevent Cerebral Hypoxia (Brain Hypoxia)?

Prevention depends on the specific cause of hypoxia. Unfortunately, hypoxia is usually unexpected. This makes the condition somewhat difficult to prevent.

You can prevent Cerebral Hypoxia by monitoring certain health conditions. See a doctor if your blood pressure is too low, and keep your inhaler nearby at all times if you are asthmatic. Avoid high altitudes if you are susceptible to altitude sickness. For people who are unexpectedly deprived of oxygen (during a fire, for example), immediate cardiopulmonary resuscitation (CPR) helps to prevent the condition from getting worse.

Possible Complications of Cerebral Hypoxia (Brain Hypoxia)

Complications of cerebral hypoxia include a prolonged vegetative state. This means the person may have basic life functions such as breathing, blood pressure, sleep-wake cycle, and eye opening, but the person is not alert and does not respond to his or her surroundings. Such patients usually die within a year, although some may survive longer.

Length of survival depends partly on how much care is taken to prevent other problems. Major complications may include:

  • Bed sores
  • Clots in the veins (deep vein thrombosis)
  • Lung infections (pneumonia)
  • Malnutrition

What is the prognosis?

Recovery depends on how long the brain has been deprived of oxygen and how much brain damage has occurred, although carbon monoxide poisoning can cause brain damage days to weeks after the event. Most people who make a full recovery have only been briefly unconscious. The longer someone is unconscious, the higher the chances of death or brain death and the lower the chances of a meaningful recovery. During recovery, psychological and neurological abnormalities such as amnesia, personality regression, hallucinations, memory loss, and muscle spasms and twitches may appear, persist, and then resolve.