Idiopathic intracranial hypertension (IIH) refers to pressure in the brain that causes people to experience headache episodes and vision problems. Idiopathic means the cause is not known, intracranial means in the skull, and hypertension means high pressure.

IIH, also known as primary intracranial hypertension and pseudotumor cerebri, is a condition caused by cerebrospinal fluid (CSF) buildup in the brain. This fluid buildup causes increased pressure inside the skull. This pressure causes symptoms such as frequent or intense headache episodes and temporary loss of vision. While the condition is not life threatening, untreated IIH may cause permanent vision loss.

IIH is diagnosed in 7.8 people out of every 100,000 annually. This number continues to rise in parallel with increasing levels of obesity.

In this article, we discuss IIH, including its symptoms, risk factors, and effect on daily activities.

An image of a pressure kettle to represent the pressure a person with IIH may experience.Share on Pinterest
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IIH is a condition that causes high pressure inside the skull without a known cause. It occurs when CSF, a clear liquid that surrounds and protects the brain and spinal cord, builds up in the skull. This increases pressure on the brain and optic nerves, which can cause headache episodes and vision changes.

The condition is also known as primary intracranial hypertension, which helps to differentiate it from secondary intracranial hypertension (SIH). IIH occurs without a known cause, while SIH has an identifiable cause, such as a brain tumor, use of certain drugs, or an underlying condition.

People with IIH usually have signs and symptoms of elevated CSF pressure around the brain. A majority of them experience persistent severe headache episodes, sometimes with nausea or vomiting. Other symptoms can include:

  • changes in vision
  • loss of side (peripheral) vision
  • blind spots
  • double vision
  • neck and shoulder pain
  • tinnitus (ringing in the ears)

The increased intracranial pressure (ICP) may lead to pressure on the optic nerve. This is called papilledema, and is a common finding that can support the diagnosis of IIH. It usually affects both eyes symmetrically, and the threat of vision loss depends on its severity.

Many people may only notice or experience visual field loss at late stages. Once a person with IIH loses their vision, they are unlikely to regain it, even if they manage their ICP.

Another common symptom of IIH is transient visual obscurations, or transient loss of vision. This refers to episodes of blurred vision, followed by recovery of vision. These periods of vision loss may involve one or both eyes.

There is no known cause of IIH, which is why health experts refer to the condition as idiopathic. Doctors theorize that some cases of increased ICP could result from increased production or reduced absorption of CSF.

If doctors are able to identify a cause of ICP, such as a stroke, blood clot, brain tumor, or certain medications, they will diagnose the condition as SIH.

While IIH can affect anyone, it is almost 20 times more common in females of childbearing age who are more than 20% over the recommended weight for their height, making doctors suspect that hormones play a role in IIH. The condition can also affect males and children, but at a substantially lower frequency.

A doctor will perform several tests to check for signs of IIH. These may involve input from an ophthalmologist and neurologist, who are doctors that specialize in eyes and the nervous system, respectively.

Initially, an ophthalmologist will likely conduct a dilated eye exam to check eye health and look at the back of the eye. They may also perform a visual field exam to test peripheral vision.

A neurologist will perform tests to check that the symptoms are not the result of another condition. These tests may include:

  • a physical exam
  • brain imaging tests such as CT or MRI scans to see the structure of the eyes and the ventricles (spaces that contain CSF) in the brain
  • a spinal tap to measure CSF pressure and check for ICP

For most people with IIH, symptoms ease with treatment. The primary aims of treatment are to relieve symptoms, reduce ICP, and preserve vision.

Lifestyle and dietary modifications

Initial treatment options will typically involve lifestyle and dietary modifications. These changes can help with weight loss for individuals who have obesity, and can reduce IIH symptoms or help prevent recurrence after treatment. Doctors will be able to advise people on strategies to reach or maintain a moderate weight safely.

Medications

Doctors may prescribe several drugs for IIH. Typically, these drugs will be to help reduce CSF buildup. Some drugs may also help to reduce headache episodes. Medications a doctor may prescribe include:

  • acetazolamide
  • methazolamide
  • furosemide
  • topiramate

Lumbar puncture

A lumbar puncture, also known as a spinal tap, is a procedure that can help measure CSF pressure. It may also relieve some symptoms. It involves inserting a needle into the spinal canal to collect CSF. By observing changes in the CSF, the healthcare team will be able to recommend appropriate medications, or even surgery if needed.

Surgery

If people do not respond to medications or lumbar punctures are unsuccessful, they may require surgery to relieve pressure. Typically, a doctor may perform one of two types of surgery: optic nerve fenestration or implantation of a neurosurgical shunt.

Optic nerve fenestration involves a doctor making a small opening in the sheath surrounding the optic nerve to relieve the swelling around the nerve. This procedure can help protect vision, but does not usually reduce headache episodes.

A neurosurgical shunt is a thin tube that a doctor implants into the brain or spine to help extra CSF drain into other areas of the body. This surgery can help to protect vision and reduce headache episodes, but there is a risk of complications, such as infections and blockages.

In most cases, IIH is treatable, and symptoms will resolve. But some people may experience permanent vision loss. In situations where an individual has become blind, they may be eligible for disability benefits under the Americans with Disabilities Act.

A 2015 study found that visual disturbances, headache episodes, and risk of sleep apnea can negatively impact a person’s quality of life. Similarly, another 2015 study mentions that headache episodes significantly contribute to low quality of life in people with IIH.

Medications a doctor may prescribe for IIH can have side effects such as dizziness, confusion, visual disturbances, and difficulty concentrating. For example, taking topiramate may make operating machinery and driving dangerous, so it is advisable for people to avoid these activities while taking these medications.

While IIH is considered rare, it is advisable for a person to contact their healthcare professional if they experience recurrent, severe headache episodes and changes to their vision, such as temporary vision loss or double vision. Individuals who meet risk factor criteria (e.g., being female, 20–50 years old, or having obesity) should contact their doctor if they experience these symptoms.

IIH is a rare neurological condition that causes increased fluid pressure in the skull and around the brain for an unknown reason. Symptoms typically manifest as severe headache episodes and vision changes. These symptoms can significantly interfere with a person’s daily functioning and quality of life unless the condition is treated.

If a person notices symptoms of IIH, it is advisable they contact a doctor for a diagnosis. Treatment options to reduce pressure in the skull may involve lifestyle changes, medications, lumbar puncture, and surgery.