Idiopathic intracranial hypertension; Benign intracranial hypertension
Pseudotumor cerebri is a benign process affecting the brain that appears to be - but is not - a tumor. It is characterized by increased intracranial pressure and normal brain ventricle size. There is no evidence of tumor, infection, blocked drainage of the fluid surrounding the brain, or any other cause.
Causes, incidence, and risk factors
The major symptom of pseudotumor is increased pressure within the skull (increased intracranial pressure). The cause for the condition itself is unknown, and the diagnosis is made when other health conditions are ruled out.
The mechanism causing the elevated ICP (increased intracranial pressure) is not well understood. Possible causes of pseudotumor cerebri include a defect in cerebral spinal fluid (CSF) absorption, increased cerebral swelling (edema), or increased cerebral blood volumes.
Other factors which are possibly associated with this condition are recent weight gain, menstrual irregularities, and the presence of too much vitamin A (hypervitaminosis A).
Oral retinoid drugs and some antibiotics are other possible causes as is the stopping of steroid use after an extended period. Other conditions that have been associated with pseudotumour cerebri include renal failure, sleep apnea, and some lung diseases which lead to the retention of carbon dioxide. Less frequently, Guillain-Barre syndrome has been found to be associated.
The condition occurs more frequently in women than men. People with this condition are often obese, with women gaining a large amount of weight during the pre-menstrual part of their cycle. Headache, worse in the morning, is the most common complaint.
It may be aggravated by sudden movements, such as coughing. There may be temporary loss of vision with a change in position. If this condition is severe and untreated, it may lead to permanent vision loss.
Several conditions may cause increased intracranial pressure, including venous sinus thrombosis, infection hydrocephalus, or any intracranial mass lesion (such as a tumor). These must be ruled out before proper diagnosis of pseudotumor cerebri can be made.
- Nausea and vomiting
- Double vision (diplopia)
- Bulging fontanelle (in the infant)
- Separated sutures (in the infant)
Signs and tests
Papilledema - bulging of the optic disc in the retina of the eye - is an important sign of pseudotumor cerebri. Tests that help with diagnosis include:
- A CT Scan and MRI (will not show tumor)
- A lumbar puncture, or spinal tap (usually confirms an elevated intracranial pressure in the 250 to 400 mm CSF range. The composition of the fluid is chemically normal)
- Formal visual field testing (detects early vision loss)
Treatment must be directed at the condition causing the pseudotumor. An initial lumbar puncture is both diagnostic and therapeutic. Repeated lumbar punctures may be done to decrease the intracranial pressure and to help prevent progressive papilledema and visual loss. Other treatments may include:
- Fluid or salt restriction.
- Medications such as corticosteroids, glycerol, acetazolamide, and furosemide.
- Shunting procedures to relieve pressure due to spinal fluid retention.
- Incision of the optic nerve sheath for relief of the papilledema, and to prevent further deterioration of vision.
- Weight loss.
- Close monitoring of vision, since there is potential for progressive and sometimes permanent visual loss.
- Follow-up MRI or CT scan to exclude hidden malignancy (cancer).
The outcome varies, and sometimes the condition disappears on its own within 6 months. About 10-20% of the people diagnosed with pseudotumor cerebri experience recurrences, and there is a small percentage who become progressively worse and may eventually become blind.
Complications may occur in connection with some of the procedures used for treatment or from side effects of the various medications. Vision loss is the main serious complication of this condition.
Calling your health care provider
Call your health care provider if you or your child experience the symptoms listed above.
by Gevorg A. Poghosian, Ph.D.