Intracranial hypertension 

  • Overview


One cause of intracranial hypertension: a haematoma (blood) can be seen building up on the right side of the skull   

Acute IH: a medical emergency

When IH comes on rapidly – as the result of a severe head injury or stroke, for example – it is known as acute IH. The high pressure is either caused by a swelling of the brain or bleeding into or around the brain.

Acute IH is fatal if it is not treated promptly as a medical emergency – you will need to be admitted to hospital straight away.

Intracranial hypertension (IH) is high pressure inside the skull, which may happen suddenly or build up gradually over time. 

It's a relatively common condition with many different possible causes.

Acute IH occurs when the condition comes on rapidly as the result of a severe head injury, stroke or brain abscess, for example.

You can read more about acute IH in the box on this page.

This page focuses on chronic IH, where the pressure inside the head has built up gradually over time. This is usually caused by an underlying disease, but sometimes there is no clear reason. It is often a severe, lifelong disease.

Chronic IH is often referred to as idiopathic intracranial hypertension  idiopathic means there is no known cause.

What are the causes of chronic IH?

Some medical conditions, such as the following, can cause chronic IH:

  • brain tumour such as a glioma or meningioma 
  • a brain infection such as meningitis or encephalitis
  • hydrocephalus, which is a build-up of fluid in the cavities of the brain
  • blood vessel abnormalities such as an arteriovenous fistula (an abnormal connection between an artery and a vein)
  • blood clotting in one of the large veins of the brain known as a venous sinus thrombosis, usually caused by infection or severe dehydration

For a full list of causes, visit the IHR Foundation website.

Idiopathic IH

Idiopathic IH means there is no obvious cause for the IH. It is most commonly seen in overweight women in their twenties.

Experts do not fully understand the link between excess weight and IH, and losing weight only sometimes helps symptoms.

Idiopathic IH is also associated with:

Note that these conditions are only linked with idiopathic IH; they are not necessarily causes.

What are the symptoms of chronic IH?

Severe cases can lead to seizures, but most people with chronic IH generally experience:

  • severe throbbing headaches which are often constant, worse in the morning, aggravated by straining or coughing and associated with nausea and vomiting – they are sometimes relieved by standing 
  • changes in vision due to swollen optic nerves (known as papilloedema) – you may have blurred vision and find it difficult to watch TV or read 

You may also feel drowsy, confused and irritable, and have nausea and vomiting. Occasionally, you may hear a 'whooshing' sound in your ears.

How is chronic IH diagnosed?

IH may be suspected if you have signs and symptoms of increased intracranial pressure, such as vision problems and headaches.

A diagnosis of IH is made by ruling out other possible causes of the symptoms. The following should apply:

  • a neurological examination does not show any injuries to specific brain areas
  • CT scan or MRI scan may look normal
  • lumbar puncture (see below) shows that you have high pressure in the cerebrospinal fluid that surrounds your brain and spinal cord
  • you are awake and alert
  • no other cause of increased intracranial pressure has been found

How is chronic IH treated?

The treatment you have depends on the underlying condition causing your IH.

If you're overweight, it's important to lose weight. This often helps reduce eye symptoms and can sometimes relieve symptoms altogether without the need for medical treatment.  


You may be given any of the following medicines to treat the underlying cause and help relieve symptoms:

  • acetazolamide, which may be taken along with a diuretic (medication to remove excess fluid from the body) 
  • a short dose of prednisolone (a steroid medication) to relieve headaches, especially if you're at risk of losing vision 

The links above will take you to more information on these drugs, including their side effects. 

Lumbar punctures

You may need regular lumbar punctures to remove excess cerebrospinal fluid from your spine and skull, and to help keep down intracranial pressure. This procedure involves taking a sample of fluid from inside your lower back using a needle and syringe.


Surgery should be considered as a last resort if medication and weight loss fail to control your IH. 

You may be offered shunt surgery, where a catheter (a thin, flexible tube) is inserted into the fluid-filled space in your brain or spine to divert the excess fluid to another part of the body.

The main types of shunt surgery are:

  • lumboperitoneal shunting (shunting fluid from the spine to the abdomen)
  • ventriculoperitoneal shunting (from the brain to the abdomen)
  • ventriculoatrial shunting (from the brain to the heart)

For many, shunt surgery provides long-term relief from symptoms, although there is a small risk of complications such as infection and blockage which you should discuss with your surgeon.

Rarely, if your vision is affected you may need to have a procedure called optic nerve sheath fenestration (ONSF). The surgeon will slit open the sheath surrounding your optic nerve to relieve the pressure on the nerve and allow the build-up of fluid to escape.

ONSF is very effective at relieving this nerve pressure and helping to treat problems with vision, but the amount of fluid removed is so small that it will not make a difference to the overall high pressure inside your skull and can lead to complications that include blindness. Again, your surgeon will explain all of these risks to you if you're considering this operation.


Many patients with chronic IH find that their symptoms are relieved after treatment, although attacks of symptoms can recur.

Chronic IH is a life-changing condition and your intracranial pressure will need to be continuously monitored throughout the rest of your life.

Page last reviewed: 19/10/2012

Next review due: 19/10/2014


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The 2 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Anon93 said on 10 November 2014

There is some good information on this page, but it is severely lacking in some areas and not very up to date. There are many, many more widely recognised symptoms of IIH and it's important to note that IIH can occur (and often does) without any papilloedema. There also has been no proven link between weight and IIH as of yet.

I think it would be helpful to include some more information about the condition, there's plenty of info at which is really helpful :)

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magicsparks said on 26 October 2013

IIHUK charity is also an excellent source of info for those with IH. There are several Facebook groups for IH in general as well as locally. You are not alone and we are all willing to do what we can to help, there is a great deal of problems with gaining treatment of IH due to a vast lack of understanding of IH among doctors. Arming your self with information is your best tool to get treated, this article on IH is very accurate though there are new developments that both IHRfoundation and IIHUK have on their websites. Don't suffer in silence.

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