Increased Intracranial Pressure
Increased Intracranial Pressure
- intracranial hypertension
- elevated intracranial pressure
Increased intracranial pressure (ICP) means that the pressure inside the skull is abnormally high, which may cause damage to the brain.
What is going on in the body?
There is normally a small amount of pressure inside the skull. Any of several conditions may cause this pressure to become elevated. Unlike many other parts of the body, the inside of the skull (except in infants) is a defined space with no way to expand. Therefore, even a moderately increased pressure in the skull squeezes the brain and decrease blood flow to the brain cells.
Increased ICP can also force the brain downward onto the brainstem. This area controls vital functions like breathing, and thus if the brainstem is squeezed, the individual may die or suffer irreversible brain damage.
What are the causes and risks of the condition?
Acute (rapidly developing) increased ICP is a medical emergency and may be caused by any condition that causes bleeding into the skull, prevents blood from leaving the skull, causes the brain to swell or prevents brain fluid from draining normally.
Some conditions that can cause increased ICP include:
- brain tumors that cause the brain to swell and/or to bleed
- brain hemorrhage from a rupture aneurysm (weak spot in a blood vessel)
- brain hemorrhage following a stroke
- infection inside the skull, such as encephalitis or abscess (pus from infection) that causes brain swelling
- large ischemic strokes resulting from a blocked artery in the brain, causing the brain to swell
- certain medications that cause the brain to swell
- head injury or trauma that causes the brain to swell and/or bleeding in the skull
- clogged veins in the neck or brain that prevent blood from leaving the skull
Conditions that cause chronic (slowly developing) increased ICP include :
- a slow growing brain mass ( tumor or abscess )
- pseudotumor cerebri (a condition usually seen in young overweight females with headache)
- clogged veins in the brain
- symptomatic hydrocephalus or "normal pressure" hydrocephalus, which actually is usually associated with a chronic, mild increased ICP
What can be done to prevent the condition?
Generally, nothing can be done to prevent the condition.
How is the condition diagnosed?
The healthcare professional usually has enough reason to suspect increased ICP from the nature of the acute event, or in the case of chronically increased ICP, from the history and physical exam. An important sign of increased ICP is a mass of blown-out looking blood vessels around the optic nerve. These can be seen by looking inside the eyeball with an ophthalmoscope.
A cranial CT scan or cranial MRI scan, two special types of x-ray tests of the brain and skull, often confirm the diagnosis of increased ICP and help determine its cause. A spinal tap should not be attempted on an individual with increased ICP until a tumor or other space-occupying lesion of the brain has been ruled out with a CT scan. This is because if such a lesion is present, a spinal tap will create a pressure difference between the brain and spinal canal that could lead to protrusion of the brain stem through the base of the skull, a fatal outcome.
Long Term Effects
What are the long-term effects of the condition?
If intracranial pressure increases rapidly, death will occur without medical intervention. Some conditions cause elevated intracranial pressure to rise over a long time. These people may develop headache and/or vision loss.
What are the risks to others?
Usually, there are no risks to others. Rarely, high intracranial pressure is caused by an infection that may be contagious.
What are the treatments for the condition?
There are many different treatments, depending on the cause and degree of increased ICP. Treating the underlying cause, if possible, is the ultimate goal of therapy. However, in the setting of acute increased ICP, it may be necessary to place a shunt to drain brain fluid from the skull, or to perform emergency life-saving surgery to remove a tumor, abscess or blood clot.
Treatment may also include special medications to decrease the ICP and putting the person on a ventilator, an artificial breathing machine. Less aggressive therapy is usually required for the chronic conditions that cause increased ICP.
What are the side effects of the treatments?
Ventilators may cause infection or lung damage. Medications may have side effects, such as allergic reactions or stomach upset. Surgery and spinal taps can be complicated by bleeding, infection, or even death.
What happens after treatment for the condition?
The effectiveness of medical and surgical treatment depends on the underlying cause. If the cause is potentially curable and the ICP was lowered in time to prevent permanent brain damage, the individual may leave the hospital and go home without any further problems.
However, many times the underlying condition, such as a large stroke or tumor, is not curable, and sometimes the increased ICP may have caused irreversible brain damage before it was caught. In these instances the individual, if he or she survives, may require intense rehabilitation before going home, followed by extensive therapy over the long term.
How is the condition monitored?
Symptoms and physical examination findings are followed. Sometimes, special instruments are placed through the skin and into the skull to measure the intracranial pressure.
Cecil Textbook of Medicine, 1996, Bennet et al.