Overview of Elevated Intracranial Pressure

Increased Pressure Inside the Head

Medically reviewed by Smita Patel, MD

Pressure in the head when lying down that is relieved when upright is a symptom of elevated intracranial pressure (ICP). This is when pressure in the brain and surrounding cerebrospinal fluid increases to the point that it can cause severe brain damage and even be fatal.

Elevated intracranial pressure can be caused by a brain bleed, an infection, a brain tumor, or a head injury. In addition to headache, you may experience nausea, vomiting, and vision changes.

This article explains elevated intracranial pressure, its common symptoms, and possible complications. It also discusses the causes of increased intracranial pressure and how it is treated.

What Is Elevated Intracranial Pressure?

Intracranial means within the skull. In addition to brain tissue, the skull contains cerebrospinal fluid (CSF), which encases and cushions the brain, and blood that supplies the brain with oxygen while ridding it of toxins.

Intracranial pressure rises when one of these three components—brain tissue, CSF, and blood—requires more space.

Normal intracranial pressure levels vary by age. Normal ICP is somewhere between 5 millimeters of mercury (mmHg) and 15 mmHg. If it increases to more than 20 mmHg, structures in the brain may be impacted.

Oftentimes, the body can compensate, usually by reducing blood flow or effectively squeezing out CSF. When this is no longer possible, elevated ICP will begin to develop rapidly.

Elevated ICP Symptoms

One of the first structures to feel the strain of increased ICP is the tissue 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.

Classic signs of intracranial pressure include a headache and/or the feeling of increased pressure when lying down and relieved pressure when standing.

Other symptoms of elevated intracranial pressure include:

• Changes in behavior

• Nausea

• Seizures

• Vision changes

• Vomiting

In babies, bulging of the fontanelle (soft spot) and a separation of the sutures (the ridges on a baby's skull) can indicate increased ICP.

Related: What It Means to Have Pressure in Your Head

Visual Symptoms

The optic nerves are also commonly affected, most especially the nerves that travel from the back of the eye (retina) to the occipital lobes of the brain. Depending on the severity and duration of the increased pressure, visual symptoms can include:

• Blurred vision

• A reduced visual field

• Permanent vision loss

Papilledema is a condition in which increased intracranial pressure causes part of the optic nerve to swell. Symptoms include fleeting disturbances in vision, headache, and vomiting.

Complications

Even more concerning than optic nerve damage is how ICP can impact the brain itself. When pressure rises inside the skull, the brain can be pushed to an area of lower pressure.

By way of example, the left hemisphere is separated from the right hemisphere by tissue called the falx cerebri.

If a bleed in the left hemisphere creates enough pressure, it can push 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 the pressure builds above the 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 even death.

What Causes Elevated ICP?

There are several things that can trigger an increase in intracranial pressure. These include a brain tumor, an active bleed in the brain, or an infection that causes massive inflammation and even the production of pus.

At other times, the normal flow of fluids in and out of the brain is impeded. CSF, for example, normally flows from the ventricles in the center of the brain through small openings known as foramina. If the flow is blocked, intracranial pressure can build.

Some of the more common causes of elevated ICP include:

• Head trauma

• Tumors, both benign and cancerous

• Intracerebral hemorrhage (ruptured vessels inside the brain)

• Subarachnoid hemorrhage (bleeding between the brain and the tissue that covers it)

• Ischemic stroke

• Hydrocephalus ("water on the brain")

• Meningitis (inflammation of the tissue surrounding the brain)

• Encephalitis (inflammation of the brain itself)

Sometimes, the cause of the increased intracranial pressure is unknown. This is referred to as idiopathic elevated intracranial pressure.

Diagnosis

Elevated intracranial pressure may be diagnosed in a number of different ways. In addition to an evaluation of symptoms, a fundoscopic exam of the eye may reveal papilledema.

A spinal tap (lumbar puncture) may also provide information about intracranial pressure, particularly if there is an infection, although this can be dangerous if pressure is extremely high.

The most reliable means of measuring ICP is with an intracranial monitor, using either an intraventricular catheter inserted into the CSF layer, a subdural bolt placed adjacent to the cerebral membrane, or an epidural sensor placed outside of the membrane.

An intracranial monitor requires surgical insertion through a drilled hole in the skull. With some brain surgeries or a traumatic brain injury, an intracranial monitor may be placed immediately.

Treatment

Elevated intracranial pressure can be dangerous. The first goal is to stabilize a patient, provide sedation if needed, and relieve the pain. If the ICP is mildly elevated, a watch-and-wait approach with the elevation of the head may be all that is needed.

In more severe cases, the doctor may use mannitol (a type of sugar alcohol) or hypertonic saline (a salt solution) to draw the excess fluid into the bloodstream and away from the brain.

Intravenous steroids may help decrease cerebral inflammation. Medications like acetazolamide may slow the production of cerebrospinal fluid.

Intracranial pressure over 20 mmHg is treated aggressively. Treatments may include hypothermia (to cool the body and reduce swelling), the anesthetic propofol to suppress metabolism, or a surgery called a craniectomy to relieve brain pressure.

A Word From Verywell

Elevated intracranial pressure is a serious complication of many conditions that affect the brain. That said, early recognition and aggressive treatment can go a long way in reducing complications.

If you are facing this diagnosis with a loved one, ask questions. Understanding what is happening and "what's next" can help you cope as you face this difficult situation.

Related: The Differences Between Head Injury and a Traumatic Brain Injury