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).