Pseudotumor cerebri occurs when the pressure inside your skull (intracranial pressure) increases for no obvious reason. Symptoms mimic those of a brain tumor, but no tumor is present. Also known as idiopathic intracranial hypertension, this disorder can occur in children and adults, but it's most common in obese women of childbearing age.
In the general population, fewer than one person in 100,000 develops pseudotumor cerebri. In women age 20 to 44 years who are at least 20 percent over their ideal body weight, the incidence is 19 per 100,000. As the number of obese women increases, so does the number of cases of pseudotumor cerebri.
The increased intracranial pressure associated with pseudotumor cerebri can squeeze your optic nerve and cause vision loss. Medications often can reduce this pressure, but in some cases, surgery is necessary.
The exact cause of pseudotumor cerebri is unknown, but it may be linked to an excess amount of cerebrospinal fluid within the bony confines of your skull.
Your brain and spinal cord are surrounded by cerebrospinal fluid, which acts like a cushion to protect these vital tissues from injury. This fluid is produced in the brain and eventually is absorbed into the bloodstream. The increased intracranial pressure of pseudotumor cerebri may be a result of a problem in this absorption process.
In general, your intracranial pressure increases when the contents of your skull exceed its capacity. For example, a brain tumor typically increases your intracranial pressure because there's no room for it. The same thing happens if your brain swells or if you have too much cerebrospinal fluid.
Risk Factor :
The following factors have been associated with pseudotumor cerebri :
- Medications such as tetracycline, tamoxifen, lithium and corticosteroids
- Too much vitamin A
- Cushing's syndrome
- Underactive parathyroid glands
The most common symptom is a severe headache, which may throb in rhythm with your heartbeat and wake you from sleep. The pain often seems to originate behind the eyes, and may increase with eye movement. Nausea and vomiting also may occur. Other symptoms can include :
- Blurred or dimmed vision
- Brief episodes of blindness, lasting only a few seconds and affecting one or both eyes
- Difficulty seeing to the side
- Double vision
- Ringing in the ears that corresponds with your heartbeat
Symptoms may get worse during physical activity, especially when you contract your abdominal muscles. But some people have no symptoms and instead find out they have pseudotumor cerebri during a routine eye exam that detects swelling in the optic disk, a structure in the back of your eye. This swelling is caused by increased intracranial pressure.
If pseudotumor cerebri is suspected, a doctor specializing in eye disorders will look for a distinctive type of swelling — called papilledema — in the back of your eye. You also will undergo a visual fields test to see if there are any blind spots in your vision.
Computerized tomography (CT) or magnetic resonance imaging (MRI) scans can rule out other problems that can cause similar symptoms, such as brain tumors and blood clots. A lumbar puncture — which involves inserting a needle between two vertebrae in your lower back — can determine how high the pressure is inside your skull.
As many as 10 percent of the people with pseudotumor cerebri experience progressively worsening vision and may eventually become blind. If your symptoms have resolved, recurrence can occur — months or even years later.
Pseudotumor cerebri treatment typically begins with medications to control the symptoms. Weight loss is recommended for obese individuals. If your vision worsens, surgery to reduce the pressure around your optic nerve may be necessary.
One of the first drugs usually tried is acetazolamide (Diamox), a glaucoma drug that reduces the production of cerebrospinal fluid by at least 50 percent. Possible side effects include stomach upset; fatigue; tingling of fingers, toes and mouth; and kidney stones. If acetazolamide alone isn't effective, it's sometimes combined with furosemide (Lasix), a potent diuretic that reduces fluid retention by increasing urine output.
Corticosteroids, although they can reduce increased intracranial pressure, are rarely used for pseudotumor because they increase appetite and may cause weight gain.
Migraine medications can sometimes ease the severe headaches that often accompany pseudotumor cerebri.
Researchers aren't certain why there is a connection between obesity in women and pseudotumor cerebri. Some have suggested that excess weight around the torso increases the pressure on a person's internal organs and this, in turn, may contribute to problems in absorbing cerebrospinal fluid.
Even a small amount of weight loss may reduce the symptoms of pseudotumor cerebri. Gastric bypass surgery also has proved helpful.
If you are having severe vision problems, your doctor may recommend surgery to reduce the pressure on your optic nerves.
One procedure — called optic nerve sheath fenestration — cuts a window into the membrane that surrounds the optic nerve. This allows excess cerebrospinal fluid to escape. Vision stabilizes or improves in more than 85 percent of cases. Most people who have this procedure done on one eye notice a benefit for both eyes. However, this surgery isn't always successful and may even increase vision problems.
Another type of surgery inserts a long, thin tube — called a shunt — into your brain or lower spine to help drain away excess cerebrospinal fluid. The tubing is burrowed under your skin to your abdomen, where the shunt discharges the excess fluid. Symptoms improve for more than 80 percent of the people who undergo this procedure. But shunts can become clogged and often require additional surgeries to keep them working properly. Complications can include low-pressure headaches and infections.
Obesity has been strongly linked to pseudotumor cerebri, so it may be possible for obese women of childbearing age to reduce their risk of developing the disorder by losing weight. Because pseudotumor cerebri can cause blindness, see your doctor immediately if you experience severe headaches or vision problems — especially if you've had pseudotumor cerebri in the past.