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What is pseudotumor cerebri?
What are the symptoms of pseudotumor cerebri?
How is pseudotumor cerebri diagnosed?
How is pseudotumor cerebri treated?
Pseudotumor cerebri (also known as idiopathic intracranial hypertension) literally means "false brain tumor" and is thought to be due to high brain pressures caused by the abnormal production or poor absorption of cerebrospinal fluid (CSF) surrounding the brain. The disorder is most common in women between the ages of 20 and 50, most of whom tend to be overweight. While several theories exist, the exact reason for buildup of CSF in pseudotumor cerebri is unknown.
What are the symptoms of pseudotumor cerebri?
Symptoms of pseudotumor cerebri include headache, nausea, vomiting, and the sensation of pulsating noises within the head. In addition, due to raised pressures within the brain, the optic nerve (the nerve that carries visual signals from the eyes to the brain) may become damaged over time, leading to visual impairments.
How is pseudotumor cerebri diagnosed?
The diagnosis of pseudotumor cerebri may be suspected on the basis of the history and neurologic examination. Several tests may be required, however, in order to confirm the diagnosis and to exclude alternative causes for the symptoms (such as a brain tumor). Magnetic resonance imaging (MRI) is the imaging study of choice to rule out mass lesions and other sources for the symptoms. Although pseudotumor cerebri can not be definitively ruled in on the basis of MRI results, certain findings on brain imaging can be highly suggestive, which include unusually small ventricles (CSF spaces within the brain) and flattening of the pituitary gland due to increased pressure.
If pseudotumor cerebri is suggested based on the above evaluation, the a lumbar puncture is performed to measure the CSF pressure and further rule out other causes of symptoms, such as a viral meningitis. If the pressure of CSF is found to be abnormally high, some of the fluid can be removed while performing the lumbar puncture to see if any of the symptoms improve -- this can further confirm the diagnosis of pseudotumor cerebri.
An ophthalmologic examination is also important in cases of suspected pseudotumor cerebri in order to rule out other ocular conditions and to establish a baseline visual function which can be monitored over time to assess the progression of the disease.
How is pseudotumor cerebri treated?
If a diagnosis of pseudotumor cerebri is confirmed, certain medications, such as diuretics (water pills) may be used to reduce the buildup of CSF. Weight loss and cessation of certain drugs (including oral contraceptives and a variety of steroids) have also been shown to lead to improvement of symptoms.
In certain cases the buildup of CSF may be relieved by surgical placement of a shunt system. This system diverts the flow of CSF from the brain to another area of the body (usually the abdominal cavity) where it can be absorbed. A shunt consists of a thin silastic tube and a valve. One end of the tube is placed in CSF spaces within the brain through a hole in the skull, while the other end is tunneled under the skin to the abdomen where it is usually placed inside of the abdominal cavity, but may also be placed at other sites within the body, such as a chamber of the heart or a cavity in the lung. A valve located along the catheter maintains one-way flow and regulates the rate of CSF flow. Adjustments can be made to the shunt valve after surgery based upon the patient’s symptoms -- several adjustments of the valve may be needed before the most appropriate setting is found. Adjusting a shunt valve, which is done through the use of a special magnet, is easy and painless, and takes only a few seconds.
Surgery on the eye may also be needed to remove pressure on the optic nerve for patients who continue to be symptomatic after treatment. Surgical treatments include optic nerve sheath decompression and fenestration, where a slit is made in the covering of the optic nerve, which can alleviate swelling and slow or halt the loss of vision.
