As small as that space within the human skull is, the brain has to share it with other substances. Cerebrospinal fluid (CSF) is one such element whose role it is to encase and cushion the brain. Blood also flows into that intracranial space, supplying the brain with oxygen while ridding it of toxins.
Problems arise when one of these three components—brain tissue, CSF, and blood—requires more space. 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
A normal intracranial pressure is somewhere between 5 millimeters of mercury (mmHg) and 15 mmHg, although normal ICP levels vary by age. Any more than 20 mmHg and structures in the brain may begin to be impacted.
One of the first structures to feel the strain 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. Nausea, vomiting, vision changes, changes in behavior, and seizures can also occur.
In babies, a sign of increased ICP is the bulging of the fontanelle (soft spot) and a separation of the sutures (the ridges on a baby’s skull).
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. Blurred vision, the reduction of the visual field, and permanent vision loss are possible, depending on the severity and duration of the increased pressure.
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 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.
Causes
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 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.
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.
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.
