Idiopathic Intracranial Hypertension (IIH)

What is it?

Idiopathic intracranial hypertension – sometimes called pseudotumor cerebri – is a medical condition with a buildup in pressure of the fluid around the brain without an identified cause. The fluid is called cerebrospinal fluid (CSF) and it surrounds and bathes the brain and spine. It is normally constantly made and resorbed at a continuous rate but sometimes it can build up to abnormally high pressures in the brain. This causes “hypertension” (or high pressure) in the brain. Sometimes it can be an acute problem, coming on suddenly. More often it is a chronic condition, or one which patients have to live with for some time.

Brain Hypertension

Narrowing of the transverse venous sinus in a patient with IIH.

How did I get it?

Sometimes another condition in the brain, such as a tumor, infection or blood clot, can cause a build up of pressure. More commonly, though, we do not know the cause of the buildup of pressure. The medical word for a disease of an unknown cause is ‘idiopathic’, and so this condition is called “Idiopathic Intracranial Hypertension”, or IIH.

There are certain other medical conditions or problems which are associated with IIH, but it is not clear if these directly cause the pressure buildup or not. These include obesity, the use of certain medications and the use of certain medications.

What kind of symptoms does it cause?

Occasionally, IIH can cause no symptoms. More commonly though patients can get chronic headaches (which sometimes can be quite severe), blurring of vision, a feeling of “pressure” in or behind the eyes, double vision, temporary loss of vision or a “ringing” in the ear which occurs with the hearbeat (called pulsatile tinnitus). Other symptoms which can occur include vomiting, fatigue or tiredness, drowsiness and irritability.

How is it diagnosed?

Your doctor may perform a number of tests in order to diagnose IIH, or make sure that your symptoms are not caused by something else. These tests include:

  • eye and vision test
  • MRI scan of your brain
  • lumbar puncture (to check the pressure of the spinal fluid)

How is it treated?

At the moment there is no cure for this condition, so the goal is to improve symptoms and/or stop further worsening of vision. Traditionally, IIH is treated with a medication which reduces the production of CSF in the brain. This medication is called acetazolamide or Diamox. Sometimes, the medication will fail to control symptoms in patients, or they will not be able to tolerate the medication due to side-effects.

In this case, there are two surgical options which may be appropriate:

Venous Stenting

The increased CSF pressures in the brain is associated with narrowing of the main veins at the base of the brain. Some patients get good relief from placing stents in these veins in order to keep them open. This is still a relatively new technique, and one only performed in some centres. A lot of research is ongoing in this area, but we do know that many patients report improvement in their symptoms after a venous stenting procedure. It is performed under general anaesthetic, and you will need to stay on blood thinners for some time after the procedure. It usually involves a one-night stay in hospital afterwards.

CSF Shunting

Sometimes the medication and/or stenting fails to control symptoms. In these cases, a small tube can be placed inside the skin which drains the excess CSF from around the brain. Many patients also find good relief of symptoms from this procedure.

Brain hypertention optic nerve

Dilated optic nerve sheath and papilledema in a patient with IIH.

Brain hypertension stenosis

Venous stenting – a stent has been placed across the narrowing in the venous sinus.