Idiopathic Intracranial Hypertension

This review was undertaken to summarize the significant progress that has been made in the epidemiology of idiopathic intracranial hypertension (IIH), the changing nosology, and the diagnostic criteria and therapeutic strategy. We reviewed the pertinent literature on IIH published in major English-language journals for the last 20 years. The diagnosis, epidemiology, pathophysiology, complications, and treatment of IIH are described. IIH occurs at an average annual incidence rate per 100,000 persons of 1 to 2 for the total population and 19 to 21 in obese females of the reproductive age-group. IIH is a recognized cause of reversible vision loss in adult obese women. The diagnosis of IIH requires a documented elevation of intracranial pressure, normal cerebrospinal fluid (CSF) composition, and normal findings on neuroimaging studies. At least two primary mechanisms for the development of increased CSF pressure in IIH have been postulated and supported by experimental data: vasogenic extracellular brain edema and a low conductance of CSF outflow at the arachnoid villi. This condition may be secondarily exacerbated by compression of intracranial venous sinuses by the increased intracranial pressure, resulting in a further reduction of flow across the arachnoid villi. The therapeutic strategy is determined by visual status, which needs close monitoring. Although medical measures to lower the intracranial hypertension are successful in the majority of patients, surgical therapy should not be delayed in those with significant or progressive vision loss. Based on recent advances, a practical approach has been described for the diagnosis, early detection of visual impairment, and targeting therapy to preserve the vision or to reverse recent loss of vision in patients with IIH.