The major symptoms of pseudotumor are increased pressure within the skull (increased intracranial pressure - ICP). 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 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 large weight gains during the pre-menstrual part of the cycle. Headache, worse in the morning, is the most common complaint.

It may be aggravated by sudden movements, such as coughing. There may be transient loss of vision with a change in position. This has the potential to cause permanent vision loss, if severe and untreated.

In order to make this diagnosis, the most important conditions that need to be ruled out that can cause increased intracranial pressure include venous sinus thrombosis, infection hydrocephalus, or any intracranial mass lesion (such as a tumor).

• Headache
• Nausea and vomiting
• Double vision (diplopia)
• Bulging fontanelle (in the infant)
• Separated sutures (in the infant)

• Papilledema (bulging of the optic disc in the retina of the eye).
• A CT Scan and MRI are done to exclude tumor and are generally normal.
• A lumbar puncture (spinal tap) is done and 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 enables the detection of 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 and/or salt restriction.
• Medications: Corticosteroids, glycerol, acetazolamide, and furosemide.
• Shunting procedures from the lumbar subarachnoid space to the peritoneal cavity.
• Incision of the optic nerve sheath for relief of the papilledema, and to prevent further deterioration of vision.
• Weight loss is usually recommended.
• Close follow-up and monitoring of vision, since there is potential for progressive and sometimes permanent visual loss.
• Follow-up MRI or CT scan is sometimes necessary to exclude hidden (occult) malignancy (cancer).