IIH
The cause of IIH is unknown – idiopathic means "of unknown cause". IIH is a rare condition and studies suggest that it affects one or two in every 100,000 people, most of them women of childbearing age, but men and children are also affected.
Diagnosis
Diagnosis of IIH is made by identifying the typical symptoms of the condition and ruling out others which can cause similar symptoms. Neurological examination is usually reported as normal, with the exception of cases where papilledema is present. Imaging procedures such as CAT/CT scans and MRI scans are also reported as normal. Definitive diagnosis of IIH is made by performing a lumbar puncture which shows an above 'normal' CSF pressure of above 25cm/H2O.
Possible causes
Blood clots in the veins draining CSF from the brain can cause increased ICP (intracranial pressure). Withdrawal of steroids, large doses of vitamin A or intake of foods containing large amounts of vitamin A, use of body building–type steroids, hormonal changes and certain medications can also cause raised ICP. Statistically, the majority of IIH sufferers are "women of childbearing age" who are overweight. Many Doctors believe that there is a connection between obesity and IIH. Research supports that a 6% decrease in bodyweight can help to resolve papilledema associated with IIH. However, many sufferers find that losing weight does not improve their IIH symptoms.
Symptoms of IIH
The most common symptoms of IIH are: severe headache, papilledema, transient visual obscurations (temporary loss of vision), diplopia (double vision) and decreased visual acuity, pulsatile tinnitus ("whooshing noise" in the ears in time with the pulse), pain behind the eye and with eye movement.
Other symptoms reported by sufferers include but are not limited to: nausea, vomiting, fatigue, photophobia (dislike of and pain caused by bright light), problems with balance and spatial awareness, aphasia (difficulty using or understanding words), disorientation, loss of short-term memory (sometimes also long-term memory loss), confusion, feeling 'spaced out', decreased depth perception and peripheral vision. Some children are often too young to report their symptoms adequately and can present with many nonspecific symptoms. Although many sufferers have symptoms in common, each sufferer is an individual and should be treated accordingly.
Medical treatment
The most commonly prescribed medication is Acetazolomide (Diamox), a carbonic anyhdrase inihibitor used for glaucoma, some types of eplilespy and fluid retention. It reduces CSF production in most patients. Nearly all patients taking Diamox suffer side effects, tingling of the fingers and toes are the most common. Patients prescribed Diamox usually undergo regular blood tests and may be advised to increase their intake of potassium as the body's natural stores can be depleted. As well as standard Diamox a sustained release form of the drug is also available, 'Diamox SR'. Many patients find that the side effects are reduced in comparison with the standard form. Furosemide, a diuretic, is sometimes prescribed but has been proven to have little effect on raised ICP. On occasion Furosemide and Diamox are used in conjunction with each other. In extreme cases where sight is threatened patients may be treated with a short dose of steroids. Other medications prescribed include Topirimate, Amitriptyline, Methazolmide and more. Analgesic drugs (pain killers) are used to treat the pain associated with IIH, with varying degrees of success. As with all pain killers care must be taken as many can be addictive and some can have severe side-effects.
Some IIH patients are treated with therapeutic lumbar punctures (LPs) to remove excess CSF on a regular basis.
Non invasive pressure testing is just starting to be evaluated in the UK, but the cost of medical staff training for the procedure makes it unlikely that it will become widespread due to current economic conditions.
Surgical treatment
Surgical intervention is usually only undertaken in severe cases to protect vision or when medications and other treatments are unsuccessful or not tolerated.
Lumboperitoneal (LP) Shunt. This surgery involves diverting excess CSF by inserting a catheter into the subarachnoid space (spinal fluid filled space in the spine) around the patients waist and in to the peritoneum (abdominal cavity). Many LP shunts have a valve system and CSF resevoir.
Ventriculoperitoneal (VP) shunt. This surgery involves diverting excess CSF by inserting a catheter in to a lateral ventricle (fluid filled space within the brain) down through the neck and into the peritoneaum.
A Ventriculoatrial (VA) shunt surgery is similar to VP shunt surgery diverting excess CSF to the 3rd Atrium of the heart. Some patients have shunt systems that drain the excess CSF to the pleura of their lung.
For many, shunt surgery has proven to be a successful long term relief from IIH symptoms and raised ICP. However, occasional malfunctions, infection, blockages and over draining of shunts can occur leading to frequent shunt revision surgery.
Venous sinus stenting is also used as a surgical procedure for IIH sufferers who have Venous Sinus Stenosis. Stent surgery is performed after CT venography and manometery investigations. If the patient is found to be a good candidate, a stent is placed within the venous sinus and dilated which can result in the reduction of pressure and relieve symptoms.
Very rarely ONSF (optical nerve fenestration) may be considered if vision is severely affected or threatened. In this procedure, the sheath surrounding the optic nerve is slit, or a 'window' cut into the sheath to relieve the pressure on the nerve and allow the CSF to escape. ONSF is very effective at relieving the pressure on the optic nerves and thus helps to resolve papilledema. However the amount of CSF drained due to this procedure is negligible. ONSF has little effect on the overall ICP and can lead to complications including blindness.
Some patients symptoms may spontaneously disappear, for others a combination of medical and/or surgical treatments control their condition and they are able to lead relatively 'normal' lives. For others both medical and surgical treatments can be limited in their effectiveness and symptoms may remain. For these patients, treatments with combinations of painkillers and other medications are required to control the symptoms although their effectiveness varies.
IIH isn't a life threatening condition, but for many people it can be a life changing condition.