Idiopathic intracranial hypertension
Idiopathic intracranial hypertension (IIH), also called pseudotumor cerebri, is a condition in which there is high pressure inside the brain. IIH often causes headache and may cause problems with vision.
IIH is characterized by elevated pressure in the fluid around the brain, called cerebrospinal fluid (CSF). This fluid is normally created by the brain to provide nutrients and oxygen, and also to protect and cushion the brain in case of injury. The fluid then drains out through veins within the brain.
In IIH, the drainage of CSF fluid is thought to be partially blocked. Though the CSF pressure may be high, the rest of the brain is structurally normal. It is important to remember that there is no brain tumor in IIH. The prior term for IIH was pseudotumor cerebri; pseudo means “fake”, thus “fake” tumor.
The high pressure is transmitted to the optic nerve at the back of the eye. High fluid pressure produces swelling of the optic nerve, called papilledema. Swelling of the optic nerve can cause damage and lead to decreased vision.
What causes IIH?
The exact cause of IIH is still not known. However, IIH tends to affect a certain demographic- women in the childbearing years (usually between the ages of 20-50) who are overweight or obese. The exact relationship between weight gain and IIH is not understood, though weight is the most important risk factor. There is also a hereditary component to IIH.
Less commonly, IIH may occur in children, men, the elderly, and people who are not overweight. In these unusual cases, certain medications such as Vitamin A or antibiotics, may be the cause.
What are the symptoms of IIH?
Most commonly, elevated pressure inside the brain leads to headache. Visual loss may occur as well in IIH. Frequently, patients notice a graying or darkening of vision which lasts for a few seconds. The optic nerve swelling may eventually lead to more severe and permanent loss of vision seen as dimming, blurring or graying of vision.
Other common symptoms of IIH include: a “swooshing” sound in the ears (coinciding with the heartbeat, called pulsatile tinnitus), neck pain, back pain, and double vision. Nausea and vomiting may occur if the pressure is high.
How is IIH diagnosed?
The most important finding which can raise the suspicion for IIH is swelling of the optic nerves in the back of the eyes. This is best seen with a dilated pupillary examination. Approximately 10% of patients with IIH will have no other symptoms, but are found to have optic nerve swelling on a routine eye exam.
If IIH is suspected based on the symptoms or based on swelling of the optic nerves, then a brain scan is necessary. MRI is best, though CT may be sufficient. Some patients may even need an MRV, which is like MRI but looks at the veins draining the brain.
After the brain scan, a spinal tap, or lumbar puncture, is necessary to measure the pressure of the fluid surrounding the brain and spinal cord as well as to take a sample for analysis. It is important to examine the CSF fluid to also make sure that there is no other process such as an infection, inflammation, or tumor, which may be causing the high pressure within the brain.
As part of the diagnostic testing for IIH, Dr. Banik will perform a visual field test to check your peripheral vision. Because swelling of the optic nerves can cause loss of peripheral vision, this test is extremely important to determine the severity of the condition, as well as to guide treatment decisions. Special pictures of the optic nerves may also be performed.
Does IIH cause blindness?
Unless there is advanced visual field loss, blindness is preventable in most IIH patients. If medical treatment does not stop progressive visual loss, a surgical procedure is needed. Only 5-10% of percent of patients go blind from IIH. With close monitoring and appropriate treatment, blindness can hopefully be avoided.
What is the treatment for IIH?
Treatment of IIH depends on the severity of symptoms and the risk to vision, as measured by the peripheral visual field test. The treatment can be divided into 2 groups: medical and surgical.
Weight loss is a proven beneficial treatment for IIH. Weight loss is best achieved through reducting calories and a low salt diet. Lifestyle modification with incorporating exercise is also helpful. In extremely overweight patients, a bariatric surgical procedure may be an option for treatment. In many patients, weight loss alone has been successful in making IIH go into remission. However, weight regain can cause IIH to return.
In conjunction with weight loss, medications can also help lower the brain pressure in IIH. Diamox, also known as acetazolamide, may lower pressure by reducing fluid production by the brain. If a patient does not tolerate or cannot take Diamox, other medications such as Lasix (furosemide), Topamax (topiramate) and Naptazane (methizolamide) may also be used.
In more advanced cases of vision loss in IIH, or in patients whose headaches do not respond to medical treatment, surgery may be necessary. CSF fluid may be drained using a tube, or shunt, which goes from the brain or spinal cord into the abdominal cavity. This is called either a ventriculo-peritoneal shunt (VPS) or lumbo-peritoneal shunt (LPS).
In patients with worsening vision, a surgery called an optic nerve sheath fenestration (ONSF) may protect the optic nerve from further damage. A small hole or multiple slits are placed in the covering or sheath, of the optic nerve just behind the eye.
Research on IIH
The Idiopathic Intracranial Hypertension Treatment Trial, or IIHTT, was a research study which helped neuro-ophthalmologists determine the best treatment for IIH. Dr Banik was one of the key principal investigators in the IIHTT. The IIHTT had 165 patients with IIH who were followed for at least one year. The results from the clinical trial were published in 2014 and showed that Diamox plus weight loss was better than weight loss alone for IIH.
A new clinical research study called SIGHT is under planning which will compare medical treatment vs shunt surgery vs ONSF surgery to determine which is the best treatment for IIH. This study is sponsored by the National Institutes of Health (NIH) and will be conducted at 45 sites across the USA and Canada. Dr Banik is one of the Principal Investigators for this very important clinical trial on IIH and will begin recruiting patients in early 2019.
Dr. Banik has extensive experience with IIH, having taken care of hundreds of IIH patients over the past 20 years. She works closely with each patient, individualizing treatment to achieve the best outcome and hopefully cause IIH to go into remission.
Whether Rudrani Banik, MD is the first Neuro-Ophthalmologist you are visiting for treatment of IIH, or the last one, she will make sure she does everything in her power to find an effective treatment to help you see and function better.