Idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH), also called pseudotumor cerebri, is a condition in which there is high pressure inside the brain. IIH often causes headache and may cause problems with vision.

IIH is characterized by elevated pressure in the fluid around the brain, called cerebrospinal fluid (CSF). This fluid is normally created by the brain to provide nutrients and oxygen, and also to protect and cushion the brain in case of injury. The fluid then drains out through veins within the brain.

In IIH, the drainage of CSF fluid is thought to be partially blocked. Though the CSF pressure may be high, the rest of the brain is structurally normal. It is important to remember that there is no brain tumor in IIH. The prior term for IIH was pseudotumor cerebri; pseudo means “fake”, thus “fake” tumor.

The high pressure is transmitted to the optic nerve at the back of the eye.  High fluid pressure produces swelling of the optic nerve, called papilledema. Swelling of the optic nerve can cause damage and lead to decreased vision.

What causes IIH?

The exact cause of IIH is still not known.  However, IIH tends to affect a certain demographic- women in the childbearing years (usually between the ages of 20-50) who are overweight or obese. The exact relationship between weight gain and IIH is not understood, though weight is the most important risk factor. There is also a hereditary component to IIH.

Less commonly, IIH may occur in children, men, the elderly, and people who are not overweight. In these unusual cases, certain medications such as Vitamin A or antibiotics, may be the cause.

What are the symptoms of IIH?

Most commonly, elevated pressure inside the brain leads to headache.  Visual loss may occur as well in IIH. Frequently, patients notice a graying or darkening of vision which lasts for a few seconds.  The optic nerve swelling may eventually lead to more severe and permanent loss of vision seen as dimming, blurring or graying of vision.

Other common symptoms of IIH include: a “swooshing” sound in the ears (coinciding with the heartbeat, called pulsatile tinnitus), neck pain, back pain, and double vision. Nausea and vomiting may occur if the pressure is high. 

How is IIH diagnosed?

The most important finding which can raise the suspicion for IIH is swelling of the optic nerves in the back of the eyes.  This is best seen with a dilated pupillary examination.  Approximately 10% of patients with IIH will have no other symptoms, but are found to have optic nerve swelling on a routine eye exam.

If IIH is suspected based on the symptoms or based on swelling of the optic nerves, then a brain scan is necessary.  MRI is best, though CT may be sufficient.  Some patients may even need an MRV, which is like MRI but looks at the veins draining the brain.

After the brain scan, a spinal tap, or lumbar puncture, is necessary to measure the pressure of the fluid surrounding the brain and spinal cord as well as to take a sample for analysis. It is important to examine the CSF fluid to also make sure that there is no other process such as an infection, inflammation, or tumor, which may be causing the high pressure within the brain.

As part of the diagnostic testing for IIH, Dr. Banik will perform a visual field test to check your peripheral vision. Because swelling of the optic nerves can cause loss of peripheral vision, this test is extremely important to determine the severity of the condition, as well as to guide treatment decisions. Special pictures of the optic nerves may also be performed.

Does IIH cause blindness?

Unless there is advanced visual field loss, blindness is preventable in most IIH patients. If medical treatment does not stop progressive visual loss, a surgical procedure is needed. Only 5-10% of percent of patients go blind from IIH.  With close monitoring and appropriate treatment, blindness can hopefully be avoided.