Unless you or someone close to you has BIH you're probably asking that question.."What is BIH"?  I had never heard of it before I was recently diagnosed with it.  I'll do my best to explain my understanding of it.

* Please note that I am NOT medically qualified and can only give information that I have researched myself or experienced myself.  If you feel that you may have BIH please ensure that you speak with your GP.*

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Benign Intercranial Hypertension is basically a build up of excess fluid on the brain creating intense pressure.  Normally the fluid is continually draining away and being replaced - this isn't happening if you have BIH.

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The cerebrospinal fluid (CSF) is a clear fluid (mostly water) which bathes the brain and spinal cord. It is produced in the ventricles (hollow cavities in the center of the brain), flows through certain openings in and around the brain, and over the surface of the brain and spinal cord, and is eventually reabsorbed in the lining of the brain (the meninges). There are just a few tablespoons of CSF, but that's all you need to act as a shock absorber and nutrient medium for the central nervous system. There is quite a bit of turnover. For example, if you remove a tablespoon (as in a spinal tap), that is replaced within an hour or so.

The CSF is under pressure. There is a "normal" range of pressure. Too much pressure can be due to a variety of causes. For example, if there is a blockage in the flow at one point, fluid can get backed up behind the obstruction and you get "noncommunicating" hydrocephalus. On the other hand, if fluid is not reabsorbed as fast as it is made, the pressure also can go up ("communicating" hydrocephalus).

Sometimes the fluid pressure is elevated for no reason that anyone can figure out. It isn't a matter of too much fluid, so hydrocephalus is not the right term. Benign intracranial hypertension is such a case. By definition, the ONLY abnormality is the increased CSF pressure - there is no abnormality of the amount of fluid, or of the circulation or of reabsorption. There is NO mass, and no loss of brain tissue as a result.

http://www.medhelp.org/forums/neuro/archive/5359.html

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There is no known cause for BIH.  The condition is sometimes referred to as Idiopathic Intercranial Hypertension (IIH), the term Idiopathic meaning cause unknown.

Suggested, but medically unproved causes, include: recent weight gain, obesity, the oral contraceptive, pregnancy.  None of these suggested causes can be proved however as BIH affects old and young, men and women, fat and thin.

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To my knowledge (drawing on my own personal experience and the research I have done) it is diagnosed by looking at the eyes. 

If the person is suffering from headaches and visual disturbances an Opthamologist (hope I've spelt that correctly?) studies the eye and looks for inflammation of the optic nerves and blind spots in the field of vision.

To complete the diagnosis an MRI (brain) scan is arranged.  Because BIH mimics the symptoms of a brain tumour an MRI is essential to confirm the diagnosis.  If the symptoms are that of a brain tumour, it will show up on the MRI scan and the patient can be treated accordingly.

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Straight away the consultant neurologist will start you on medication to help drain fluid away from the brain; most commonly Diamox.

A MRI scan is organised to confirm the diagnosis.

Lumbar punctures are the next step.  A large needle is inserted into the lumbar (base) area of the spine and fluid drained off.  The pressure is monitored during this process.  Regular lumbar punctures are then usually arranged to continually drain the fluid away.

If lumbar punctures don't appear to be working then the next step is the inserting of a shunt.

*I will supply more information about the scans, lumbar punctures and shunts as I learn more.  It's not something I have personally experienced yet although I know that I will be having a MRI and lumbar punctures.* 

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That depends on the individual.

Worst case scenario is losing your sight and becoming permanently blind.

Many BIH sufferers continue to work, others find that they are unable to, or they need to change the type of work that they do.

At present there is no known cure.  It can be managed with medication and lumbar punctures (and in some cases shunts).

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