Idiopathic intracranial hypertension (IIH) happens when high pressure around the brain causes symptoms like vision changes and headaches. “Idiopathic” means the cause isn’t known, “intracranial” means in the skull, and “hypertension” means high pressure.

IIH happens when too much cerebrospinal fluid (CSF) — the fluid around the brain and spinal cord — builds up in your skull. This puts extra pressure on your brain and on the nerve in the back of your eye, called the optic nerve.

If you notice changes in your vision, talk to your eye doctor. The doctor can figure out if your symptoms are related to IIH or another condition. If it’s IIH, there are treatments that can help with the symptoms.

Pseudotumor cerebri literally means "false brain tumor." It is likely due to high pressure within the skull caused by the buildup or poor absorption of cerebrospinal fluid (CSF). The disorder is most common in females between the ages of 20 and 50. Symptoms, which closely mimic those of large brain tumors, include:

• Headache
• Nausea
• Vomiting
• Pulsating sounds within the head

Obesity, other treatable diseases, and some medications can cause raised intracranial pressure and symptoms of pseudotumor cerebri. Diagnosis is based on a thorough medical history and physical examination. If a diagnosis is confirmed, close, repeated ophthalmologic exams are required to monitor any changes in vision.

Drugs may be used to reduce fluid buildup and to relieve pressure. Weight loss through dieting or weight loss surgery and cessation of certain drugs (including oral contraceptives, tetracycline, and a variety of steroids) may lead to improvement. Surgery may be needed to remove pressure on the optic nerve. Therapeutic shunting, which involves surgically inserting a tube to drain CSF from the lower spine into the abdominal cavity, may be needed to remove excess CSF and relieve the pressure.

The disorder may cause progressive, permanent vison loss in some individuals. Pseudotumor cerebri can be a recurring problem. 

IIH is rare, but some people are at higher risk. It’s most common in women ages 20 to 50.

Being overweight or obese also makes IIH more likely. You may be at higher risk if you have a body mass index (BMI) greater than 30, or if you recently gained weight.

Experts don’t know what causes IIH. But there are other types of intracranial hypertension that do have known causes:

• Acute intracranial hypertension happens suddenly, usually because of an accident or stroke
• Chronic intracranial hypertension develops over time, usually because of a health problem like a blood clot or brain tumor, or from taking certain medicines

If doctors can’t find a reason for the high pressure, it’s called IIH.

Symptoms can include:

• Headaches
• Tinnitus (ringing in the ears)
• Temporary blindness
• Double vision
• Blind spots
• Neck and shoulder pain
• Peripheral (side) vision loss

If you notice any changes to your vision or other symptoms, talk to your eye doctor.

Did you know?

IIH symptoms are often similar to the symptoms of a brain tumor — so IIH is sometimes called pseudotumor cerebri, or “false tumor.”

About 19 out of 20 people with IIH are women.

Your eye doctor will do several tests to check for signs of IIH, including a dilated eye exam to look at the back of your eye and a visual field test to check your peripheral vision.

Your eye doctor may also want you to see a neurologist (a doctor specializing in the brain). The neurologist will check to make sure your symptoms aren’t happening because of another health problem, like a brain tumor. The neurologist may do tests including:

• A physical exam
• Brain imaging, like a CT or MRI scan
• A spinal tap (lumbar puncture) to test your CSF

For most people, IIH symptoms get better with treatment. Treatments include:

Weight loss. For people who are overweight or obese and have IIH, weight loss is usually the first treatment. Losing about 5 to 10 percent of your body weight can help lessen your symptoms — for example, if you weigh 200 pounds, that means losing about 10 to 20 pounds. Talk with your doctor about safe, sustainable ways to lose weight.

Medicine. Your doctor may recommend a medicine called acetazolamide (Diamox) in addition to weight loss. This medicine helps your body make less CSF.

Surgery. If other treatments don’t work, your doctor might suggest surgery to help relieve the pressure. In shunt surgery, doctors make a small hole and add a thin tube, called a shunt, to help extra fluid drain from around your brain into the rest of your body. There is also an eye surgery where doctors make a small hole in the covering around the optic nerve.

Researchers are studying what causes IIH, including how genes and hormones might play a role.

In 2010, NEI funded a clinical trial to test the medicine acetazolamide (Diamox) in IIH patients with mild vision loss. This trial helped to prove that acetazolamide, along with a weight loss plan, can help to restore some vision in people with IIH. It also helped create clear guidelines for doctors on how to prescribe acetazolamide for patients with IIH.