Idiopathic Intracranial Hypertension

What causes pressure within the skull to increase is unknown. However, certain people are more susceptible to idiopathic intracranial hypertension because the large veins (venous sinuses) that help drain blood from their brain are smaller than in most people. In these people, blood drains from the brain more slowly, causing a back-up of blood, which increases pressure in the brain and/or within the skull.

Exactly how being overweight contributes to increased pressure within the skull is unknown. But excess fat in the abdomen may increase pressure in the chest, and blood may not flow from the head to the chest as it normally does. Thus, pressure within the skull may increase.

In idiopathic intracranial hypertension, the increased pressure does not result from other identifiable disorders, such as tumors, infections, blood clots, 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 growth hormone is used. Sometimes the disorder develops after people take tetracycline antibiotics Tetracyclines Tetracyclines are a group of antibiotics used to treat many different bacterial infections. Tetracyclines include the following: Doxycycline Eravacycline Minocycline read more or large amounts of vitamin A.

Idiopathic intracranial hypertension usually begins with a daily or almost daily headache, which affects both sides of the head. 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 noises within the head that occur with each beat of the pulse (called pulsatile tinnitus Ear Ringing or Buzzing Ringing in the ears (tinnitus) is noise originating in the ear rather than in the environment. It is a symptom and not a specific disease. Tinnitus is very common—10 to 15% of people experience... read more ). 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 Papilledema Papilledema is a condition in which increased pressure in or around the brain causes the part of the optic nerve inside the eye to swell. Visual symptoms may be fleeting disturbances in vision... read more . Doctors can observe the swelling by looking at the back of the eye through an ophthalmoscope Ophthalmoscopy A person who has eye symptoms should be checked by a doctor. However, some eye disorders cause few or no symptoms in their early stages, so the eyes should be checked regularly (every 1 to 2... read more .

The first sign of vision problems is loss of peripheral (side) vision. People may not notice this loss at first. As a result, people may bump into objects for no apparent reason. Vision may be blurred briefly, sometimes triggered by changing position, and blurring may come and go. Late in the disorder, vision is blurred, and people may quickly become blind. As many as one third of people lose their vision, partially or completely, in one or both eyes. Once vision is lost, it usually does not 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. Doctors closely monitor and treat such people to prevent loss of vision.

Idiopathic intracranial hypertension recurs in about 10 to 20% of people.

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

If doctors suspect idiopathic intracranial hypertension, they check the field of vision Visual Field Testing A person who has eye symptoms should be checked by a doctor. However, some eye disorders cause few or no symptoms in their early stages, so the eyes should be checked regularly (every 1 to 2... read more (the entire area of vision that is seen out of each eye), including peripheral vision. They also examine the interior of the eye with an ophthalmoscope if they have not already done so.

Magnetic resonance venography is done to evaluate the large veins (called venous sinuses) that carry blood from the brain. This test enables doctors to determine whether the venous sinuses are narrowed or blocked. Narrowed venous sinuses may be the only abnormality that imaging tests detect in people with idiopathic intracranial hypertension. Magnetic resonance imaging (MRI) of the brain is also done to check for other abnormalities that could increase pressure within the skull.

A spinal tap Spinal Tap Diagnostic procedures may be needed to confirm a diagnosis suggested by the medical history and neurologic examination. Electroencephalography (EEG) is a simple, painless procedure in which... read more (lumbar puncture) is done to measure the pressure of cerebrospinal fluid and to analyze the fluid. In idiopathic intracranial hypertension, the pressure of the fluid is increased, often to very high levels. The content of the fluid is usually normal. As soon as spinal fluid is removed during the spinal tap, the pressure inside the head decreases, the venous sinuses may widen, and more blood may flow from the brain. As a result, the headache lessens.

These and other tests can help identify or rule out other possible causes of increased pressure within the skull (such as a brain tumor blocking the venous sinuses).

Idiopathic intracranial hypertension occasionally resolves without treatment.

Treatment of idiopathic intracranial hypertension focuses on the following:

Aspirin, acetaminophen, or drugs used to treat migraines (especially topiramate—see table Some Drugs Used to Treat Migraines Some Drugs Used to Treat Migraines ) may relieve the headache. Topiramate can also help people lose weight and help lower the pressure within the skull.

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