Brain herniation occurs when the brain tissue is forcibly pushed from one side of the skull to the other side or downward, resulting in a life-threatening increased pressure inside the skull.
The brain is supported within the skull by a horseshoe-shaped piece of tough tissue called the tentorium. The brainstem connects to the brain through an opening in the tentorium. This is where most herniations occur. Conditions that cause swelling in the brain or increased pressure in the skull can cause brain tissue to be pushed into this opening.
In addition, the right and left brain hemispheres are almost entirely separated by a similar structure called the falx cerebri that extends from the inside top of the skull. If the brain is pushed from one side to the other, the hemisphere on the side of the increased pressure can herniate under this structure.
For instance, if there is a mass, such as a tumor, in the head, the brain will swell. Since the skull is rigid, swelling will force the brain into the area of least resistance. The swelling may result in the brain shifting from its usual position to an abnormal position in the skull causing brain herniation.
Symptoms usually start with a loss of alertness that can progress into complete loss of consciousness. As the herniation increases, one or both pupils of the eyes may dilate. The respiratory rate and rhythm may change, requiring the individual to be placed on a ventilator. The individual may experience paralysis of one or both sides of the body.
Anything that causes swelling in the brain might lead to herniation. Some common causes include: bleeding in the brainbrain tumorbrain contusion from from a blow to the head stroke
Brain herniation can cause severe brain damage or even death. The ability to breathe, keep the heart beating, be alert, and think can all be damaged.
Some causes cannot be prevented. For instance, a brain tumor cannot be prevented. But other diseases that cause bleeding in the brain, such as stroke, may respond to treatment which, if given in time, will decrease brain swelling and prevent herniation.
A person can help prevent injury to the head by following sports safety guidelines for adults, adolescents, and children. This includes wearing appropriate headgear, such as a helmet, when: playing baseball, football, or other physical sportsriding a motorcycle or bicycleskiing or snowboarding
Diagnosis is based on the person's medical history as well as characteristic signs and symptoms. Special tests that take pictures of the inside of the skull and brain, including cranial MRIs and cranial CT scans, can help confirm the diagnosis.
If brain herniation is not treated quickly, the person will stop breathing and die.
There are no risks to others.
This is a medical emergency, so treatment must be started right away. Initially, treatment is aimed at reducing the brain's swelling. Identification and treatment of the cause of the herniation is also important. The person may require surgery or be given medicine through an intravenous line, called an IV, to help decrease swelling.
Side effects of surgery include infection, bleeding, and possibly death. Medicines may cause side effects, such as allergic reactions and chemical imbalances, that need to be treated right away. Close monitoring is critical during treatment.
A person is often left with severe impairments, including: cognitive impairments, which are problems with thinkingmobility impairments, which are problems with movementspeech impairments, which are problems with talking
If the person has significant impairments, it is important to begin rehabilitation with specialized therapists and professionals who are trained to treat brain injuries.
All vital signs, such as heart rate, blood pressure, breathing rate, body temperature, and pressure inside the skull, should be monitored during treatment. After the crisis is over, ongoing monitoring of the problem that caused the herniation may be needed. Any new or worsening symptoms should be reported to the healthcare professional.
