Idiopathic Intracranial Hypertension

What Is Idiopathic Intracranial Hypertension?

Idiopathic intracranial hypertension (IIH), or pseudotumor cerebri, is a cerebrovascular disorder in which cerebrospinal fluid builds up around your brain without a known reason, increasing the pressure in your skull. Cerebrospinal fluid (CSF) is a clear liquid that nourishes and protects the brain and spinal cord.

Pseudotumor cerebri, which means false brain tumor, is an older but still used term for IIH.

IIH is defined as:

Idiopathic =“unknown cause”
Intracranial = “within the skull”
Hypertension = “high pressure”

Increased pressure in IIH can cause headaches and swelling of the optic nerve (papilledema). The optic nerve carries information between your brain and eye and helps you see.

How Common Is Idiopathic Intracranial Hypertension?

IIH is a rare condition that affects mainly women and is strongly associated with obesity. Overall, about two new cases occur in every 100,000 people each year. In women between the ages of 15 and 44 who have obesity, the rate is 22 in 100,000.

At Penn Medicine, our specialists have the experience needed to accurately diagnose IIH and preserve your vision.

Pseudotumor Cerebri Symptoms and Signs

Headaches are the most common symptom of idiopathic intracranial hypertension. These headaches may become progressively worse and more frequent and can impact your quality of life.

Other symptoms include:

Blurred or darkened vision
Dizziness
Double vision
Neck or back pain
Whooshing or thumping in the ears that matches your heart rate (pulsatile tinnitus)

Rarely, IIH can lead to permanent blindness.

What Causes Idiopathic Intracranial Hypertension?

Intracranial hypertension is the result of a buildup of cerebrospinal fluid. Normally, your brain continuously produces and reabsorbs CSF to main a constant volume. In intracranial hypertension, there is a loss of CSF balance due to increased production or decreased absorption of CSF.

Often, intracranial hypertension has a known cause. For example, acute (sudden) intracranial hypertension can occur because of a stroke or blow to the head. Intracranial hypertension can also develop over time due to conditions such as a brain tumor or medications.

But in pseuotumor cerebri, the cause of the high pressure in your skull is usually not known. In some cases, IIH may be related to narrowing of the large veins that drain blood from the brain (venous sinus stenosis).

IIH Diagnosis

Your doctor will assess your symptoms and medical history and perform a physical exam. Tests your doctor may use to diagnose IIH or rule out other conditions include:

Blood tests to exclude other conditions that can cause intracranial hypertension
Diagnostic venogram, an X-ray taken after injecting dye into a vein, to view blockages such as venous sinus stenosis
Eye exam to look for swelling of the optic nerve and evaluate vision changes
Imaging tests, such as CT or MRI, to rule out other brain conditions or known causes of intracranial hypertension
Lumbar puncture (spinal tap) to measure the pressure of your cerebral spinal fluid and collect a sample of fluid for laboratory testing
Neurological exam to find out if there are problems with other nerves, besides the optic nerve (which indicates the problem is not IIH)

Can Idiopathic Intracranial Hypertension Be Cured?

IIH is rarely curable, but weight loss, medications and surgery can significantly reduce symptoms and preserve vision. For people with venous stenosis and IIH, venous stenting is a very effective treatment.

Pseudotumor Cerebri Treatment at Penn Medicine

IIH is usually associated with obesity, so weight loss is a primary treatment. Your doctor may recommend losing five to 15 percent of your weight to reverse the symptoms of IIH.

Medications are also a treatment option to help:

Decrease the production of CSF
Reduce overall fluid retention in your body
Relieve headaches

If other treatments are not effective or if your vision is in danger, your doctor may recommend surgery to improve CSF drainage. Surgical procedures to treat pseudotumor cerebri include:

CSF diversion surgery: The surgeon places a long thin tube (shunt) between your brain and abdomen to drain CSF.
Venous stenting: In this relatively new technique, the surgeon inserts a thin tube (catheter) into a blood vessel and advances it to the venous sinuses in the brain. They thread a metal mesh hollow tube called a stent through the catheter and open it to fit inside the vein. The stent eliminates the outflow obstruction in the venous sinuses.