Medication and Surgery
Both drugs and surgery are used to treat chronic IH. Medical (or Drug) therapy is generally tried first, but if there is an immediate risk to vision, chronic pain that cannot be relieved or a poor response to drug therapy, then surgery is performed. It is not unusual for people with chronic IH to undergo both drug therapy and surgery in an effort to control their intracranial pressure.
Carbonic Anhydrase Inhibitors
Carbonic anhydrase is a crucial enzyme needed in the production of cerebrospinal fluid. When this enzyme is suppressed, production of CSF decreases, which also lowers intracranial pressure.
The most common carbonic anhydrase inhibitor and the main drug used to treat chronic IH is acetazolamide (Diamox). Methazolamide (Neptazane), a similar drug from the same family as acetazolamide, can also be prescribed. Other drugs with carbonic anhydrase inhibiting properties include furosemide (Lasix) and topiramate (Topamax).
Acetazolamide was originally developed to treat glaucoma by reducing the production of aqueous fluid within the eye, which lowers intraocular pressure. Acetazolamide is a sulfonamide but its molecular structure differs from sulfa drugs, which means that certain people who are allergic to sulfa antibiotics may still be able to take acetazolamide. However, any treatment should first be discussed with and supervised by your physician.
Daily dosages of acetazolamide can range from 1-4 grams depending on the individual. In addition, potassium supplements may be necessary since most carbonic anhydrase inhibitors are diuretics, as well. Many people notice tingling in their face, hands and feet; a metallic taste when drinking carbonated beverages; fatigue; and a lack of appetite when they first begin taking acetazolamide. These initial side-effects tend to dissipate over time.
If drug therapy is successful, surgery can sometimes be avoided. However, carbonic anhydrase inhibitors have several drawbacks. The drugs block other similar enzyme systems elsewhere in the body (i.e. the eyes and the kidneys), with unknown effects. Some who take acetazolamide may develop kidney stones; the drug also carries a very rare risk of aplastic anemia, a serious blood disorder.
Carbonic anhydrase inhibitors can be difficult to tolerate long-term and for some people, the drugs are just not effective. But since no drug has been specifically developed to treat chronic IH, they are currently the only option.
Treatment of pain, especially headache pain, can be challenging. In addition to using carbonic anhydrase inhibitors, some physicians try to treat the headache that accompanies chronic IH. Medications for chronic headache like tricyclic anti-depressants, beta-blockers and calcium-channel blockers may be used, depending on the individual.
The long-term use of corticosteroids to treat chronic IH has fallen out of favor, unless there is a secondary inflammatory process caused by an underlying disease like lupus or Behcet disease. While corticosteroids may lower intracranial pressure in the short-term, the drawbacks to steroids include weight gain, fluid retention and a rebound in intracranial pressure during the drug’s withdrawal.
Prescription pain medication may also be a part of drug therapy. While most pain medications have little effect on headaches caused by intracranial hypertension, they may temporarily affect the intensity of a headache for some people.
It’s not uncommon, especially among those who are undiagnosed, to turn to over-the-counter headache medications in search of relief. But excessive use of these drugs can lead to rebound headaches, as well as other conditions, like thinning of the blood. While the relationship between headache pain and IH is not fully understood, lowering intracranial pressure remains key to reducing chronic IH pain.
In 2007, researchers at Athens General Hospital in Greece published the results of a clinical study in which 26 patients with idiopathic intracranial hypertension (IIH) were treated with octreotide, a synthetic hormone that is sometimes used in the treatment of tumors and in certain endocrine disorders. The results were very positive but octreotide as a possible therapy for IIH needs to be evaluated in a controlled, double-blind study, something both the study’s researchers and IHRF advocate.
To read more: http://www.ihrfoundation.org/hypertension/info/C172
Optic Nerve Fenestration
When sight is at risk and drug therapy has been unsuccessful, an optic nerve fenestration (also called an optic nerve sheath decompression) is usually performed. The operation can be done on one optic nerve sheath (unilateral) or on both optic nerve sheaths (bilateral).
During surgery, a small window-like opening is made in the sheath around the optic nerve, which allows cerebrospinal fluid (CSF) to drain behind the eye and relieves optic nerve swelling. This surgery is done primarily to save vision, rather than to alleviate headaches.
Shunt operations are also performed when drug therapy has been unsuccessful. Shunts may be used to control papilledema and prevent vision loss, as well as to treat headaches that have been unresponsive to any medication. A neurosurgical shunt is a surgically-implanted catheter that is used to drain CSF into another area of the body such as the abdomen. A shunt lowers intracranial pressure by removing CSF to another site, where it can be absorbed.
Most Common Types of Shunts
Lumboperitoneal shunt (LP shunt)
An LP shunt diverts CSF from the lumbar sub-arachnoid space (spine) to the peritoneum (abdominal cavity).
Ventriculoperitoneal shunt (VP shunt)
A VP shunt diverts CSF from a ventricle in the brain to the peritoneum (abdominal cavity).
Cisterna magnum shunt
A cisterna magnum shunt diverts CSF from the cervical cistern (back of the head) to the peritoneum (abdominal cavity). These types of shunts are generally used when it is not possible to use an LP or VP shunt.
Other areas of the body into which CSF can be drained include the pleural cavity (chest), and the atrium (heart).
Many shunts used today have programmable valves, which means that the valves are externally adjustable. The advantage of a programmable valve is that after surgery, a physician can adjust the valve’s rate of drainage non-invasively, with the use of a magnetized device. Shunts with programmable valves can be affected by magnets used to produce MRIs, and may need to be adjusted after the imaging is completed.
Shunts have a checkered history with an initial 50% success rate and alternately, a high revision rate of 50%.The most common problem with shunts is that the catheter becomes blocked and has to be replaced. Shunts are the most common pediatric neurosurgical procedure and the second most common neurosurgical procedure for adults.
Some people with IH who are either non-responsive to medication or are intolerant of it, and who have also been found to have a true narrowing (stenosis) of a major venous channel at the base of their brain, may be candidates for a surgical procedure known as stenting.
The stenosis is detected on imaging studies (CT or MR venography), which is then confirmed by actual direct pressure measurement within the narrowed vein (direct angiography). The presence of a true stenosis restricts blood flow through a large venous blood vessel, thereby raising blood pressure within the cerebral venous system. (This pressure is different than arterial blood pressure, which is measured by your doctor with an arm cuff)
As fresh CSF is continually produced within the brain, “used” CSF normally drains unidirectionally into the cerebral venous sinuses, after circulating in the subarachnoid space. If the venous blood pressure is abnormally high from a stenosis, then CSF pressure must correspondingly rise in order to flow into the venous sinus. This cause of intracranial hypertension can be relieved by surgically placing a stent (a small, tube-like device) in the stenotic area, which improves blood flow and lowers both venous blood pressure and the cerebrospinal fluid pressure.
While cerebral venous sinus stenosis is not a common finding for most people with IH, people who do have stenosis and undergo stenting often experience a significant improvement in the signs and symptoms of intracranial hypertension. Therefore, all patients with unexplained intracranial hypertension should undergo imaging (venography) to rule out the presence of a true stenosis.
There is no “perfect” treatment for chronic IH, especially since every person’s experience is different. While surgery certainly helps some people, it can also lead to repeat operations, which can sometimes produce serious, even life-threatening complications. To make an informed decision, it is always best to discuss both the risks and benefits of any treatment with your physician.