About Idiopathic Intracranial Hypertension
Putting a stent in a cerebral vein (venous sinus stenting)
Idiopathic intracranial hypertension (IIH) occurs when there is elevated pressure in the cerebrospinal fluid. Little is known, however, about what causes IIH. Experts think it occurs when there is too much cerebrospinal fluid (CSF) in the skull, possibly because it isn’t being absorbed properly or because too much CSF is being produced. Researchers have found that some patients with IIH have a narrowing (stenosis) of veins (venous sinuses) in the brain, but they do not know if the narrowing is the cause or the result of IIH.
Who is most likely to develop IIH?
Women are more likely to develop IIH than men. In particular, obese women who are in their child-bearing years are more than 20 times more likely to develop this condition.
Are you at risk for IIH?
- You may be at a higher risk if you:
- Are a female who is 20-45 years old
- Are obese
- Take growth hormones, oral contraceptives or tetracycline
- Recently stopped taking steroids
- Have too much Vitamin A in your system
Several medical conditions also may be associated with IIH including:
- Addison’s disease
- Kidney failure
- Cushing’s disease
- Iron deficiency anemia
- Head injury
- Lyme disease
- Polycystic ovary disease
- Sleep apnea
What are the symptoms of IIH?
Several symptoms are related to IIH, including:
- Blurred or double vision
- Vision loss or brief episodes of blindness that last a few seconds
- Blind spots when you look to the side
- Light flashes
- Tinnitus (ringing in your ears)
- Dull headaches behind your eyes or at the back of your head
- Nausea or vomiting
These symptoms often get worse during physical activities.
Nearly 10 percent of individuals with IIH experience vision loss. Therefore, it is very important to be properly evaluated if you have any of these symptoms.
An individual’s eye doctor may be the first person to suspect IIH. The doctor may see swelling of the optic nerve, called papilledema, during a routine eye exam or a visit based on the patient’s concerns about headaches or recent vision changes.
Swelling of the optic nerve is one finding of IIH. This swelling can cause vision loss, so it is important to determine what is causing it. If your eye doctor suspects IIH he or she may order an MRI scan and refer you to a neuro-ophthalmologist or neurologist for more testing.
Evaluations and testing
The IIH Team at the Swedish Neuroscience Institute includes many specialists who have experience diagnosing and treating IIH.
Tests may include:
- A thorough eye exam, which not only tests how well you see up close and in the distance, but also:
- Visual field testing to determine if there are blind spots in your central or peripheral (side) vision
- Color vision testing
- Tests to evaluate your pupil function
- Eye movement testing
- An assessment of the appearance of the optic nerves inside the eye to determine whether there is swelling of the optic nerve (papilledema)
- MRIs to (1) look for signs of IIH, (2) be certain there is no other condition that might be causing increased pressure, and (3) assess blood flow through the veins in the head (venous sinuses)
Lumbar puncture (LP), also known as a spinal tap, is used to check the pressure of the cerebrospinal fluid (CSF) and to analyze its contents. An LP is a procedure in which a needle is inserted into the spinal canal of patient with IIH to collect cerebrospinal fluid for diagnostic testing. It is a safe procedure.
The procedure is typically performed under local anesthesia using sterile technique, and often with Xray guidance. A needle is used to access the subarachnoid space from which the pressure is checked and fluid is collected. Fluid is usually sent to a lab for biochemical and microbiological analysis, and for a cell count.
Lumbar puncture should not be performed if you have a tendency for bleeding.
The most common side effect of an LP is a spinal headache, which is a headache that occurs only when sitting up, and indicates an internal CSF leak from the lumbar puncture site. It is painful but not dangerous, and can be treated by bedrest, or by a blood patch, where your own blood is injected back into the site of leakage to cause a clot to form and seal off the leak.
During the LP, contact between the needle and a spinal nerve root can result in pain and tingling in a leg during the procedure; this is harmless and very brief.
Serious complications of a properly performed LP are extremely rare, but include bleeding, inflammation, and nerve damage.
Because of the threat of blindness, it is very important for patients who have symptoms of IIH to be evaluated by a specialist who has experience with this condition.
Usually, the first approach to treatment for IIH is conservative. Individuals with IIH due to medication use (for example, minocycline or doxycycline) need to stop taking the causative medication, and may need additional treatment, depending on the severity of the IIH. If IIH is due to sleep apnea, the sleep apnea needs to be treated.
Acetazolamide is a diuretic (“water pill”) that works well at getting symptoms of IIH under rapid control. Almost all IIH patients are put on acetazolamide to lower the CSF pressure to reduce symptoms and lessen the chance of vision loss. Another option is topiramate, which works well to decrease CSF pressure, and helps with migraine headaches. Other diuretics and steroid medications are sometimes used.
For the longer term, weight loss is necessary for treatment of IIH that is brought on by obesity. A number of investigators have shown that weight loss is a cure for patients with IIH due to obesity. In general, it takes weight loss of between 10 to 20% of your body weight to cure IIH. You will need to determine your weight loss goal with your treatment team. There is some evidence that using a low-sodium diet is beneficial.
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The best scientific evidence so far is that combining weight loss, aerobic exercise, and acetazolamide gets IIH under control most rapidly with a sustained response.
A patient’s treatment plan may include periodic lumbar punctures to remove some cerebrovascular fluid and, thus, relieve pressure on the brain.
Vision loss in patients with IIH can come on quickly. Therefore, if your primary symptom is worsening vision, rather than headache or other symptoms, a neuro-ophthalmologist may recommend surgery to reduce the swelling in the optic nerve. This surgery is called optic nerve sheath fenestration (perforation). Sometimes this surgery is done on an emergency basis to protect your eyesight.
What happens during optic nerve sheath fenestration surgery?
Both an ophthalmologist and an anesthesiologist will talk with you before the procedure to ensure you understand everything that will happen. This procedure reduces the risk of blindness, but it does not cure IIH. Therefore, even after optic nerve sheath fenestration, you will need continued follow-up treatment.
The surgery takes place in an operating room. You will be lying on your back on the operating table. When you are completely asleep, the surgeon will prepare your eye so it stays open throughout the procedure. The surgeon then performs a series of procedures to expose the covering (sheath) of the optic nerve. Next, the surgeon will make a series of small incisions to release the pressure on the optic nerve.
What happens after the surgery?
After your surgery, the OR staff will move you to the recovery room. After you are awake, the transport team will move you to a room in the hospital. You will probably not have to spend the night in the hospital. Your surgeon will prescribe an antibiotic to help protect you from an eye infection, and also may prescribe antibiotic-steroid drops, which you will use for the first week. Usually recovery is pain-free and does not require pain medicine. We will schedule you for a follow-up visit one to two weeks after your surgery.
Surgery to implant a shunt
In some cases, the most appropriate treatment is placement of a shunt to help drain the extra fluid and reduce its pressure. This procedure consists of implanting a small tube (shunt or catheter) into chambers in your brain called ventricles, or into the spinal fluid space in the lower back. The shunt allows the CSF to drain into your abdomen, where it is absorbed. A valve is attached to the shunt to control how much CSF drains. The shunt:
- Helps prevent CSF from building up
- Reduces pressure on your brain
- Improves your symptoms and reduces the likelihood of vision loss
What is a shunt?
The shunt moves fluid from one place to another. The system includes:
- Two tiny tubes (catheters)
- A one-way valve that connects the two tubes
The valve is about the size of a silver dollar from one end to the other, but it is very thin and narrow. The valve allows fluid to move only one way – away from your brain.
How does a shunt work?
Shunts can be placed in various locations. Your surgeon will talk with you about these options.
- Typically, one of the tubes runs from the ventricle in your brain to the valve, with the other tube running from the valve to your abdomen. This is called a ventriculoperitoneal shunt.
- Sometimes the first tube may be placed into the lower spine, where CSF also circulates, and the second tube placed in your abdomen. This is called a lumboperitoneal shunt.
- The second tube may also end at a blood vessel near the heart or in the space around the lungs, instead of the abdomen.
The shunt system allows extra spinal fluid to drain into an area where it can be safely absorbed by your body. The valve can be adjusted to control the flow of fluid. This keeps fluid from building up, but also ensures the right amount of fluid is still available to protect and cleanse your brain.
What happens during the surgery to implant the shunt?
Before surgery, your neurosurgeon will talk with you about the procedure to be certain you understand everything that will take place. Your anesthesiologist will also talk with you.
The shunt implant surgery takes place in an operating room at the hospital. The procedure takes about 30 minutes. The anesthesiologist will give you medicine so you are completely asleep during the procedure, and will monitor you throughout the procedure.
If you are undergoing a ventriculoperitoneal (VP) shunt placement, the nursing staff will shave a small section of hair on your head. They will also thoroughly wash your head and abdomen with a special soap. This ensures the area is sterile.
When you are asleep, the neurosurgeon will make a small incision in your scalp, and a small hole in your skull and one in the protective covering of the brain. The surgeon will use special imaging equipment, called intra-operative navigation, to see inside your brain and locate the correct place for the shunt. The neurosurgeon will make an additional incision (usually above or behind your ear) to assist with placement of the tubing.
One end of the shunt is placed in the ventricle. The other end is connected to the valve. The second tube is connected to the other end of the valve. This tube is then tunneled just beneath your skin down to the abdomen below your ribs. The tubing is inserted into the abdomen either through a small incision, or with the assistance of a general surgeon using a laparoscope and two tiny incisions.
After placing the shunt and valve, the doctor will cover the incisions with sterile bandages.
After the procedure, the OR team will move you to the recovery room. Once you are awake, the transport team will move you to a room in the hospital. You will stay overnight in the hospital, so we can monitor you during your recovery. Most patients leave the hospital after one or two days.
Will the shunt be visible after surgery?
You will notice a small lump behind your hairline and above your ear where the valve is located. Your hair will grow back in that area, so it will not be noticeable to most people.
Recovering after surgery
Some of your activities will be limited when you first leave the hospital. For example, you should not lift anything heavier than 10 pounds for two to four weeks, and you should not resume driving if you are taking narcotic pain medication. Although the valve is beneath the skin on your head and protected, you should be careful not to bump it.
You should have someone look at your incisions every day. You should call your surgeon’s office if they notice any signs of infection, such as:
- Redness and hardness around the incision
- Hot to the touch
- Green or yellow discharge
- Excessive bleeding
- The incision is getting bigger
- The incision has a bad smell
During the first few months our clinical scheduler will make several follow-up appointments for you at the clinic. During those visits, we will check the valve and ensure you are recovering well. Your doctor will also check to make sure the spinal fluid is flowing correctly. We use special equipment that allows us to adjust the valve in the clinic – even though it is beneath your skin – to make the flow just right. After the first few months, you will have checkups once a year.
The neurosurgeon also may prescribe physical therapy or an appointment with a rehabilitation specialist if you have any problems with walking, standing or balancing.
Will all of my symptoms go away after surgery?
Inserting a shunt should help reduce headaches, dizziness, and nausea and vomiting. How much you improve will depend on how serious your symptoms were by the time you had surgery. The shunt may also improve symptoms related to your vision.
A reminder: A magnet, like the magnets in an MRI, can affect the valve and possible change the setting. If you need an MRI, please let the doctor know about your valve. After you have an MRI, you will need to schedule an appointment for us to check your valve setting in the clinic.
CT scan and MRI studies have shown that many patients with IIH have narrowing of one or both of the transverse sinuses, which are the large cerebral veins inside the skull near the back of the brain. This narrowing, or stenosis, results in back-up of venous blood, causing impaired drainage of cerebrospinal fluid and increased pressure in the head. Some investigators believe that this narrowing of the transverse sinuses is a consequence of IIH, but many believe that sinus stenosis can worsen or actually cause IIH.
Studies have shown that some patients with IIH get better when a stent, or mesh tube, is placed into and expands a narrowed transverse sinus (sinus stenting) if they are not responding to medical treatment and weight loss. The stent is placed into the venous sinus by means of a large cathether that is inserted into the femoral vein, in the groin, then guided into the transverse sinus with Xray guidance.
The complication rate of venous sinus stenting in low, but includes rupture of a vein, which might cause bleeding outside or inside the brain.
Neuro-ophthalmologists at the Swedish Neuroscience Institute in Seattle were participants in a phase II clinical trial conducted by the Neuro-Ophthalmology Research Disease Investigator Condortium (NORDIC). The National Institutes of Health sponsored this trial, called the IIH Treatment Trial (IIHTT). The study is no longer recruiting subjects.
The trial evaluated participants who have mild vision loss due to IIH. The research was intended to establish evidence-based treatment strategies, to possibly determine risk factors for getting the disease, and to improve our understanding of the natural history of the disease. The study also followed the patients who participate in the study for up to four years to evaluate the outcomes from treatment.
The primary objective of the study was to determine whether losing weight and implementing a low-sodium diet, along with taking a diuretic (medicine that reduces the amount of fluid in the body), reduced or reversed vision loss associated with IIH. The study determined that individuals with IIH did better with treatment with acetazolamide along with weight loss, compared to those with weight loss alone.
A study comparing surgical treatments for IIH is being planned. The doctors at the Swedish Neuroscience Institute plan to participate in this study.