Idiopathic intracranial hypertension (benign intracranial hypertension, pseudotumor cerebri) involves increased pressure within the skull (intracranial pressure), without any evidence of a cause.

• People have daily headaches, sometimes with nausea, blurred or double vision, and noises within the skull.
• Imaging of the head is done to rule out possible causes of increased pressure, and a spinal tap is done.
• Without prompt treatment, vision can be lost.
• Weight loss, diuretics to reduce fluids in the brain, and spinal taps done periodically to reduce the pressure can help, but surgery is sometimes needed.

Idiopathic intracranial hypertension occurs in only about 1 of 100,000 people, usually in women during their reproductive years. However, among young overweight women, it is 20 times more common. As more and more people are becoming overweight, the disorder is becoming more common.

Pressure in the skull may be high in some cases because the large veins (venous sinuses) that carry blood from the brain are blocked. These changes cause blood to back up in the veins, including those that carry blood from the skull. The increased pressure does not result from tumors, infections, or blockages that prevent the fluid that surrounds the brain (cerebrospinal fluid) from draining as it normally does.

In most people, the development of idiopathic intracranial hypertension cannot be traced to any particular event. In children, this disorder sometimes develops after corticosteroids are stopped or after a child has taken large amounts of vitamin A or the antibiotic tetracycline.

Symptoms

Idiopathic intracranial hypertension usually begins with a daily or almost daily headache. At first, the headache may be mild, but it varies in intensity and may become severe. The headache may be accompanied by nausea, double or blurred vision, and pulsating noises within the skull (tinnitus). A few people do not have any symptoms.

Increased pressure within the skull may cause the optic nerve to swell near the eyeball—a condition called papilledema. Doctors can observe the swelling by looking at the back of the eye through an ophthalmoscope.

The first sign of vision problems is loss of the peripheral (side) vision. As a result, people may bump into objects for no apparent reason. Late in the disorder, vision becomes blurred. About 5% of people lose their vision, partially or completely, in one or both eyes. Once vision is lost, it may never return, even if the pressure around the brain is relieved. In some people, the disorder becomes chronic and progressively worse, increasing the risk of blindness. However, close monitoring of such people can prevent loss of vision.

The disorder recurs in about 10% of people.

Diagnosis

Doctors suspect this disorder based on symptoms and results of a physical examination. Sometimes doctors suspect it when they detect papilledema during a routine examination with an ophthalmoscope.

Then an imaging test, usually magnetic resonance imaging (MRI), is done to check for other possible causes of increased pressure within the skull. One type of MRI (called magnetic resonance venography) can provide images of the veins that carry blood from the brain. It enables doctors to determine whether these veins are narrowed. If results are normal, a spinal tap (lumbar puncture) is done to measure the pressure of the cerebrospinal fluid and to analyze the fluid. In idiopathic intracranial hypertension, the pressure of the fluid is usually increased, and the content is usually normal.

Treatment

Idiopathic intracranial hypertension often disappears without treatment within 6 months. Nonetheless, overweight people should lose weight because doing so reduces pressure within the skull. The disorder may resolve when as little as 10% or 20% of body weight is lost. However, weight reduction programs are often unsuccessful.

Drugs known to trigger the disorder, such as tetracycline, should be stopped.

Aspirin, acetaminophen, or drugs used to treat migraines may relieve the headache. Doctors may prescribe acetazolamide to help reduce the pressure. This drug is a diuretic, which helps the kidneys eliminate water in urine and thus decrease the amount of fluid in the body, including the brain.

The usefulness of doing spinal taps daily or weekly to remove cerebrospinal fluid is debated. If this treatment is used, people are closely monitored to determine whether pressure is decreasing.

People are closely monitored by an ophthalmologist so that vision problems can be recognized as soon as possible.

If vision deteriorates despite these measures, surgery to reduce pressure within the skull may be needed and may be able to save vision. In one procedure (called optic nerve sheath fenestration), slits are cut in the covering of the optic nerve behind the eyeball. These slits allow cerebrospinal fluid to escape into the tissues around the eye, where the fluid passes into veins. Alternatively, a permanent drain (shunt) can be surgically placed so that excess cerebrospinal fluid can be removed. The shunt is a piece of plastic tubing placed in the spaces within the brain or in the space just below the spinal cord in the lower back. The tubing is run under the skin, usually to the abdomen, where excess fluid can drain.

If magnetic resonance venography detects a blockage in a vein, a tube made of wire mesh (stent) may be inserted through an incision into a vein in the neck and placed in the blocked vein to hold it open.

If people are obese and other measures are ineffective, surgery to help with weight reduction (bariatric surgery, such as a gastric bypass—see Obesity and the Metabolic Syndrome: Bariatric Surgery) may be done. If successful, it may cure the disorder.

Last full review/revision April 2008 by Stephen D. Silberstein, MD