Bright Sight

Oliver Backhouse, Consultant Eye Surgeon www.cataract.org.uk

Intracranial Hypertension/Pseudotumour Cerebri

What is Pseudotumour Cerebri?

Pseudotumour cerebri (PCT) is a condition in which high cerebrospinal fluid (CSF) pressure inside your head can cause problems with vision and headache. The term “Pseudotumour” (which means "false tumour") comes from the days before CT and MRI brain scans, when doctors who noted swelling of the optic disc (the visible portion of the optic nerve in the back of the eye) considered the possibility of a brain tumour. Patients with optic disc swelling but no evidence of a tumour were said to have "Pseudotumour".

In PCT, the flow of the CSF (a clear fluid that bathes the brain and the spinal cord) is blocked from flowing back out of the head as it should, leading to high pressure inside your head. This pressure results in swelling of the optic disc at the back of the eye, which can damage (sometimes permanently) the optic nerve, causing vision loss. High pressure may also give damage to the nerves that move the eyes, resulting in double vision.

What causes Pseudotumour Cerebri?

The reason for the decreased outflow of CSF is not clear. Because this condition seems to occur more often in overweight young women, a hormonal influence is suspected. Pseudotumour may also occur in children, men, and patients who are not overweight. In some cases, antibiotic or steroid use may be associated with Pseudotumour. A high dose of vitamin A may also lead to increased CSF pressure.

What are the symptoms of Pseudotumour Cerebri?

The most common symptoms of high CSF pressure inside the head are headache and visual loss. The headache may be located anywhere, but is frequently in the back of the neck. This pain may awaken the patient in the middle of the night, and may worsen with bending or stooping.

  • Symptoms of Pseudotumour cerebri include:
  • Dimming, blurring or graying of vision.
  • Difficulty seeing to the side.
  • Brief visual disturbance (often associated with bending or stooping)
  • Double vision.
  • Rushing noise in the ears.
  • Nausea and vomiting.

How is Pseudotumour cerebri diagnosed?

Your ophthalmologist will carefully measure your vision, check the light reaction of your pupils, examine the back of your eye and may evaluate your field of vision. Because other conditions may produce similar symptoms to PCT, an MRI scan is necessary for accurate diagnosis. A spinal tap is also necessary to check for elevated CSF and to make sure there are no other CSF abnormalities.

How is Pseudotumour cerebri treated?

If you have no significant headaches or evidence of vision loss (including visual fields) no treatment may be necessary. If you do experience these problems, certain medications used in treating glaucoma (Diamox – Acetazolamide) can lower the CSF pressure in the head by reducing the production of this fluid. Diuretics may also be used. One of the most effective treatments is weight reduction in overweight patients. Pressure may also be lowered by draining off CSF through repeated spinal taps.

Repeat visual field testing is essential in following patients with PCT. If your visual field is worsening or you experience a decrease in central acuity of vision, a small hole may be placed in the optic nerve sheath (called optic nerve sheath fenestration) just behind the eye using an operating microscope. This is done to protect the optic nerve from further damage. If severe headaches accompany the visual loss, a shunting procedure (lumbo-peritoneal or ventriculo-peritoneal) may be required.

1] Do I have a tumour?

While the most commonly used term "Pseudotumour" has that word in it, by definition patients with PCT specifically do not have a tumour. A tumour may cause increased intracranial pressure and therefore be mistaken for PCT but this should be seen on an MRI scan.

2] When will this go away?

It was thought in the past that PCT was a self-limited disease that resolved over 1-2 years. While it is possible for the pressure to vary over time, prolonged problems with CSF outflow may result in long-term increased pressure.

3] Do I need to be treated?

If you have no significant headaches or evidence of visual loss (including visual fields) no treatment may be necessary (weight reduction is always a good idea). The decision to start treatment or to alter treatment from dietary to medical to surgical intervention depends on the function of the optic nerve and the status of the headaches. Headaches that do not respond to over-the-counter medications and, even more importantly, evidence of damage (particularly progressive damage) to the optic nerve function are indicators that treatment is necessary.

4] I hate those visual fields. Can’t you just look at the back of the eye?

Unfortunately the appearance of the optic nerve (papilloedema) does not tell us how well your optic nerve is working. To determine whether there is further damage to the optic nerve acuity and visual field testing is necessary.

5] Do I need another spinal tap?

In the past we treated PCT with repeated spinal taps. This is not effective in most patients. While we would like to know the intracranial pressure, re-measuring becomes important only when there is evidence of further damage to the optic nerve (worsening visual field or visual acuity) or worsening headaches. It is then important to distinguish between inadequately treated intracranial pressure and some possible additional cause of worsening symptoms. As mentioned, if the pressure on the repeat spinal tap is low there still may be a need for further monitoring. Fortunately this form of problem producing worsening symptoms is rare.