Idiopathic Intracranial Hypertension: Emerging Concepts

of increased intracranial pressure (ICP) without a recognizable cause, typically associated with headache and papilledema. The historic term “benign intracranial hypertension” has been abandoned in modern clinical practice. IIH is used to indicate the clinical features of increased ICP secondary to nonobstructive causes, as elevated ICP is associated with a significant risk of vision loss. IIH is most prevalent in women of gestational age, although it can, rarely, affect men and children, and in those groups often has atypical features. Although the specifi c cause of IIH is unknown, it has been closely associated with obesity and has increased in prevalence parallel to rising obesity rates. In this review, we discuss emerging aspects in the clinical features, diagnosis, and treatment of IIH to update a review published in this series in 2013. Epidemiology and Pathophysiology Past reviews have demonstrated the incidence of IIH in the general population to be 0.5 to 2.0 per 100,000 people, increasing to 19.3 per 100,000 in overweight women of gestational age. The incidence of IIH has doubled over the past 2 decades in parallel to the obesity epidemic in the United States and elsewhere. The frequent co-occurrence of IIH and obesity suggests that truncal obesity may cause high intra-abdominal pressure that is transmitted to the superior vena cava and inhibits venous drainage from the brain. However, incidence rates and symptoms differ between obese men and women, suggesting that factors other than obesity are at play, and the infl uence of hormonal factors has been speculated. More than 90% of patients with IIH are female. Therefore, any male patient with presumed IIH should be evaluated closely for secondary causes of raised ICP such as venous sinus thrombosis. Men with IIH also have a higher risk of vision loss than women. Although obesity and sex are the largest risk factors in adults, there is no association with obesity in children.