Sometimes called Benign Intracranial Hypertension or Pseudotumour Cerebri, idiopathic intracranial hypertension (IIH) is a rare condition affecting up to two in every 100,000 people. Most are women and the usual age of onset is mid-twenties.
IIH can also occur in children, affecting boys and girls equally, and in older adults.
Onset can be sudden or insidious; it may be associated with being overweight, but losing weight does not appear to halt the disease, although American research suggests that a 6% weight loss helps to resolve the problem of associated papilloedema (swelling of the optic disc).
The causes of IIH are unclear. However, always present are:
The symptoms reported are those usually associated with raised intracranial pressure (ICP) such as headache, visual disturbances, photophobia, vomiting, problems with balance and spatial awareness, disorientation, loss of short-term memory (sometimes long-term memory loss), “pins and needles” or loss of sensation in the hands. In some cases, CSF leaks down the nose.
It is important to exclude cerebral tumour as a cause of the symptoms. People with raised ICP may find it difficult to cope with previously learnt everyday tasks, such as handling money or using the telephone. They may be unable to find their way around a previously familiar town: traffic is confusing, they can be unaware of kerb height (sometimes afraid to step off the kerb in case they step “into space”); crossing the road can be a nightmare.
Diagnosis of IIH is by scan and measurement of the CSF pressure. On a CT scan, the ventricles (chambers in the brain) will usually appear normal or small.
The CSF pressure should always be measured despite the “normal” scan results. It will be found to be raised on lumbar puncture. On examining the eyes, there may be swelling of the optic disc, often indicating the need for surgical intervention.
Most people with IIH appear perfectly normal, but IIH can be very disabling. Relationships suffer. Headache can be constant and normal sleep patterns disturbed. Depression is not uncommon.
11-35% of people recover spontaneously; in others, management is variable. Some people do very well on a regime of diuretics and steroids but must be monitored symptomatically, and by CSF pressure measurement to protect the eyesight.
There is little evidence that drug therapy improves the long-term outcome, although a short (two week) course of steroids may be enough to re-open the vein pathways sufficiently so that the IIH resolves.
Where sight is affected, it may be necessary to open up the optic nerve (by slitting the sheath surrounding the nerve): everyone with IIH should be under the care of an ophthalmic surgeon.
Some people need repeated lumbar punctures to remove excess CSF, or the excess CSF may need to be diverted by means of a surgically inserted shunt. A lumbar peritoneal shunt is usually the shunt of choice, though various options may be tried.
Once a shunt is in place, the person is at risk of complications sometimes associated with shunting, such as infection, blockage, and, most commonly in IIH, overdrainage. Back pain and sciatica or arachnoiditis (a painful inflammation disorder) may occur after lumbar peritoneal shunting.
Surgery should be considered only if there is deterioration in vision, despite drug therapy or diet; inability to tolerate medication or non-compliance with taking medicines; or severe headaches which are proved to be associated with raised CSF.
After surgery or when CSF pressure is apparently successfully reduced by drugs, headaches may still occur. These can be debilitating and may need to be treated with combinations of painkillers.
Complementary therapies such as cranial osteopathy, Indian head massage and reflexology are often very helpful, but should only be used with the agreement of your neurologist or neurosurgeon.
