in one of the lateral ventricles of the brain, usually by stereotactic surgery, and then connected either to the right atrium of the heart or the peritoneal cavity, respectively. Given the reduced need for revisions in ventricular shunts, it is possible that this procedure will become the first-line type of shunt treatment. It has been shown that in obese people, bariatric surgery (and especially gastric bypass surgery) can lead to resolution of the condition in over 95%. Prognosis It is not known what percentage of people with IIH will remit spontaneously, and what percentage will develop chronic disease. IIH does not normally affect life expectancy. The major complications from IIH arise from untreated or treatment-resistant papilledema. In various case series, the long-term risk of one's vision being significantly affected by IIH is reported to lie anywhere between 10 and 25%. Epidemiology On average, IIH occurs in about one per 100,000 people, and can occur in children and adults. The median age at diagnosis is 30. IIH occurs predominantly in women, especially in the ages 20 to 45, who are four to eight times more likely than men to be affected. Overweight and obesity strongly predispose a person to IIH: women who are more than ten percent over their ideal body weight are thirteen times more likely to develop IIH, and this figure goes up to nineteen times in women who are more than twenty percent over their ideal body weight. In men this relationship also exists, but the increase is only five-fold in those over 20 percent above their ideal body weight. Despite several reports of IIH in families, there is no known genetic cause for IIH. People from all ethnicities may develop IIH. In children, there is no difference in incidence between males and females. From national hospital admission databases it appears that the need for neurosurgical intervention for IIH has increased markedly over the period between 1988 and 2002. This has been attributed at least in part to the rising prevalence of obesity, although some of this increase may be explained by the increased popularity of shunting over optic nerve sheath fenestration. History The first report of IIH was by the German physician Heinrich Quincke, who described it in 1893 under the name serous meningitis The term "pseudotumor cerebri" was introduced in 1904 by his compatriot Max Nonne. Numerous other cases appeared in the literature subsequently; in many