Elevated Intracranial Pressure

What Causes Pressure in the Head?

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What exactly does it mean if a person has increased intracranial pressure? What are the symptoms of elevated intracranial pressure, what causes it, and how is it treated? What can happen to the brain if the pressure in the head stays too high?


Intracranial pressure is a measure of the pressure in the brain and surrounding cerebrospinal fluid. When this pressure is increased for some reason—whether due to a bleed in the brain (hemorrhage), an infection, or a head injury—the brain may suffer severe damage. In fact, the elevated intracranial pressure is one of the most feared complications of traumatic brain injury. Let's explain why.


The skull, when you think about it, isn’t very big. In those few square inches of hollowed bone is everything you remember, every quirky personality trait, every one of your special skills or talents, all held in a few precious pounds of brain.

As small as that space is, the brain has to share it. Cerebrospinal fluid (CSF) surrounds the brain, encasing and protecting the brain from bashing against the skull with every jolt of your head. Blood flows into that intracranial space as well, supplying the brain with the oxygen it craves and ridding the brain of toxic byproducts.

Other components of the body have to share spaces as well, but those areas are not enclosed quite so rigidly as the brain. There are just a few openings out of that skull through which nerves and the spinal cord can travel. Other than that, there’s no way in or out of that intracranial space.

All this is well enough in day-to-day life. It’s a good thing that our brain is so well protected with this kind of natural helmet, or we’d be prone to all kinds of brain injury. Problems arise, though, when one of the three main components of the intracranial space requires more room. These components include:

  • Intracranial blood
  • Brain tissue
  • Cerebrospinal fluid

If something needs more space, something else has to give. At first, compensatory actions take place between these three components. When this is no longer possible, however, since this is taking place in the rigid containment of the skull, intracranial pressure begins to rise rapidly.


There are a few different processes and mechanisms which can result in an increase in intracranial pressure.

Sometimes, something is in the head that shouldn’t be there. Examples include a brain tumor, blood due to hemorrhage in the brain. Sometimes infection or inflammation lead to swelling and pus in the brain.

Other times, the normal way fluids shift in and out of the intracranial space is interrupted. For example, CSF normally flows from the ventricles in the center of the brain through small openings known as foramina. If this CSF flow is blocked somehow, and CSF continues to be made, pressure builds.

Some risk factors for elevated intracranial pressure include:

Sometimes there is an increase in intracranial pressure for unknown reasons. This is referred to as "idiopathic" elevated intracranial pressure.


A normal intracranial pressure is somewhere between 8 to 20 millimeters of mercury (mm Hg). Any more than this and structures in the brain may begin to be impacted. One of the first structures to feel the strain are the tissues known as meninges that surround the brain. Whereas the brain itself lacks pain receptors, the meninges can fire off pain messages that result in a terrible headache.

High intracranial pressure often causes a classic headache or a sensation of pressure in the head when lying down; because the high intracranial pressure is improved by standing up and worsened by lying flat. Standing allows some of the pressure to descend down the spinal column, whereas laying flat evens out the pressure gradient, resulting in higher pressure surrounding the brain.

Another structure to be impacted relatively early as intracranial pressure rises are the optic nerves, the nerves that travel from the back of the eye (the retina) to the area of the brain where vision is interpreted (the occipital lobes). People with high ICP may start to complain of blurring of their vision as the optic nerves are damaged. In addition to the visual loss, there is often visual field loss and a physician may note papilledema on a fundoscopic exam—when a doctor uses the tool next to the instrument which looks in your ears to look at the retina—of the eyes. If the intracranial pressure isn’t fixed in a reasonable amount of time, permanent vision loss can result.

Other symptoms of increased intracranial pressure may include nausea and vomiting, behavioral changes, and seizures. A change in mental status, such as lethargy and eventually coma is a serious sign.

In babies, a sign of increased intracranial pressure is bulging of the fontanelle (the soft spot) and sometimes separation of the sutures (the ridges on a baby's skull.)


Even more concerning than optic nerve damage (and resultant damage to vision) is how ICP can impact the brain itself. When pressures rise inside part of the skull, the brain can be pushed to an area of lower pressure. The lobes of the brain are divided by rigid slices of tissue. For example, the left hemisphere is separated from the right hemisphere at the top of the brain by the tissue called the falx cerebri. If a bleed in the left hemisphere creates enough pressure, it can push the brain of the left hemisphere under the falx cerebri, crushing brain tissue and blocking off blood vessels. Brain damage and stroke can result.

Similarly, the cerebellum is separated from the rest of the brain by the tectorial membrane. If pressure builds above that membrane, brain tissue can be pushed down through the small opening near the brainstem, causing irreparable brainstem damage. This can lead to paralysis, coma, and death.


Elevated intracranial pressure may be diagnosed in a number of different ways. Symptoms noted above may suggest that pressure is elevated. A fundoscopic exam of the eye may reveal papilledema. A spinal tap may also provide information about intracranial pressure, though this can be dangerous if pressure is very high.

The most reliable method of measuring intracranial pressure is through inserting a monitor underneath the skull. This procedure provides a continuous readout of intracranial pressure. With some brain surgeries or with a traumatic brain injury an intracranial pressure monitor has usually placed right away.


It should now be clear that elevated intracranial pressure can be dangerous. However, neurologists are highly skilled at diagnosing and often treating this condition, which is a common neurological complication for many critically ill patients.

Most of the time, an intracranial pressure over 20 to 25 are treated aggressively.

Fortunately, neurologists have a number of ways to manage high ICP when the time is of the essence. While nothing is guaranteed, timely intervention can prevent serious debilitation.

The first goal is to stabilize a patient, provide sedation if needed, and relieve pain. If the increase is only slight, simple measures such as elevating the head may reduce intracranial pressure to a small degree by allowing the blood in the neck to flow back into the heart.

The next step is to maximize room in the brain for sensitive nerve tissue. Solutions such as mannitol or hypertonic saline are often given as they draw fluid into the bloodstream and away from the brain. Steroids may also decrease swelling in the brain. Medications such as acetazolamide may slow the production of cerebrospinal fluid. If a patient is on a ventilator, the respiratory rate is often increased as well. Stage three therapies may include hypothermia, metabolic suppression, or a craniectomy. A craniectomy involves removing a part of the skull in order to give the brain more room to expand as it swells.


The prognosis of elevated intracranial pressure may vary widely, depending on the underlying cause, how high the pressure rises, and how long the pressure stays elevated. It will also depend on the specific treatments which are used.

A Word From Verywell

Elevated intracranial pressure is a common and serious complication of many conditions which affect the brain. That said, early recognition and aggressive treatment can go a long way in reducing the complications. If you are facing this concern with a loved one, ask questions. Any medical concern can be terrifying, but those which affect our ability to think and learn and dream carry even more anxiety. Understanding what is happening and what the next steps may be can help you cope as you face this difficult problem.

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