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Idiopathic Intracranial Hypertension

Also known as: Benign Intracranial Hypertension, Pseudotumour Cerebri

Background

Idiopathic intracranial hypertension (IIH) is a condition where intracranial pressure ((ICP) the pressure of fluid in the head) is raised. This increase in ICP is usually accompanied by papilloedema (swelling of the nerve at the back of the eye). IIH occurs in all people of all ages and is more common in females. Up to 37 per cent of cases occur in children and teenagers. Cases in very young children up to the age of one year have also been reported. IIH occurs in 1 per 100,000, however, in young obese women, this rises to 19 to 20 per 100,000. Women in their twenties are at particular risk of suffering from IIH. In order for IIH to be diagnosed, other conditions (eg brain tumour) must be excluded. A brain scan and cerebrospinal fluid (CSF; the fluid from around the brain and spine), must be normal. In IIH, the patient's ICP may remain high for years, but symptoms can be controlled by lumbar puncture, shunts or medication (see 'How is it treated?' section). IIH as a condition can be self-limiting, meaning it will resolve itself after a certain amount of time. IIH patients may experience problems with their vision and approximately ten to 30 per cent of patients with IIH will have persisting permanent visual problems.

Credits

Medical text written March 2010 by Mr J Goodden, Locum Consultant Paediatric Neurosurgeon, Leeds General Infirmary, UK, and Mr N Buxton, Consultant Paediatric Neurosurgeon, Alder Hey Children's Hospital, Liverpool, UK.

What are the symptoms?

Headache is the most common symptom in IIH, occurring in 90 per cent of patients with this condition. It is most severe in mornings and worsens with coughing or sneezing.

Visual disturbance is reported in 35 to 80 per cent of IIH patients and includes:

  • temporary vision loss or 'blacking out'
  • gradual vision reduction
  • peripheral vision loss
  • double vision.

These episodes can occur without the patient realising and may not be totally eliminated even with successful treatment of IIH.

Other symptoms of IIH include dizziness, nausea and tinnitus.

What are the causes?

True benign intracranial hypertension means that there is no underlying cause but the many other possible causes of similar conditions need to be excluded. There is an association with medications given for various conditions including tetracyclin, istotretinoin, trimethoprim, sametadine, lithium, naradoxic acid and tamoxifen. If symptoms of benign intracranial hypertension develop in the presence of these medications, then they should be stopped if possible. The patient themself can help the situation by weight loss and it is reported that simply by losing weight, the symptoms can be resolved spontaneously.

How is it diagnosed?

The following tests are used to diagnose IIH:

  • brain scan (computed tomography scan (CT)/magnetic resonance imaging (MRI)); these should be normal
  • eye examination
  • lumbar puncture (a process in which CSF is removed from the lower back).

How is it treated?

IIH is monitored closely through outpatient examinations, which include regular visual testing. Headache diaries are helpful in monitoring. If an underlying cause of IIH is identified, its treatment will usually control IIH. Excess weight will need addressing and loosing seven to ten per cent of body weight may improve headaches and vision. Weight loss should be achieved through a dietician-lead calorie-controlled diet plus exercise. When there is no clear cause, IIH can be treated through lumbar punctures, medicines or surgery.

Lumbar puncture involves draining CSF from the lower back, thus reducing ICP. A lumbar puncture is performed under local or general anaesthetic, usually general anaesthetic for children. Intermittent lumbar puncture to reduce pressure is usually an effective treatment for IIH.

Treatment with acetazolamide reduces CSF production and thus reduces ICP. Other dehydrating medicines, such as furosemide, can be tried but are less effective. Steroids can also be tried as alternative.

When lumbar puncture or drug therapies are unsuccessful or when vision is deteriorating, surgical treatment will be considered. Shunts (a tube draining CSF from the brain or spine into the abdomen) can be used to reduce ICP and there are many different types available. A subtemporal decompression, a technique whereby a 'window' is made in the side of the skull thus reducing ICP, can also be performed. Optic nerve fenestration or decompression is another surgical option. In this procedure, slits or a large hole are placed in the optic nerve sheath and fluid drains out, thereby taking pressure off the optic nerve and preventing sight loss.

Inheritance patterns and prenatal diagnosis

Is there support?

Idiopathic Intracranial Hypertension (IIH) UK

Email: info@iih.org.uk
www.iih.org.uk

IIH UK is a Registered Charity in England and Wales No. 1143522. It provides information and support to sufferers, their families and friends. It has an online support forum and holds regional social gatherings. 

Group details last updated August 2014.

Information and support in the UK for idiopathic intracranial hypertension is also provided by SHINE (Spina Bifida•Hydrocephalus•Information•Networking•Equality; see entry Spina Bifida).

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