Idiopathic intracranial hypertension: important questions answered with more to come.

Abstract

There have been nearly 100 articles written per year over the last 30years about idiopathic intracranial hypertension (IIH).1 Despite these reports,manyquestions remain concerning IIH including a need for better understanding of the etiology and risk factors for disease development, the concern that a single measurement may not reflect the dynamic and variable nature of intracranial pressure, a lack of uniform agreement concerning medical management with diuretics, and finally a continued lack of uniform guidelines concerning thenecessity and timingof surgical intervention (shunt vs optic nerve sheathdecompression).Unfortunately, despite all of our best efforts, many patients ultimately lose significant amounts of vision. Additionally, in some patients, there continues to be difficulty distinguishing papilledema frompseudopapilledema. The current issue of JAMA Neurology contains preliminary results of the Idiopathic IntracranialHypertensionTreatment Trial (IIHTT).2 The IIHTT is a multicenter, randomized, double-blinded, placebo-controlled study of weight reduction and low-sodiumdiet coupledwith acetazolamide vs placebo in patients with IIH andmild vision loss. The current article reportsonpatientcharacteristicsandexaminationfindings in patients with IIH and mild vision loss. Through their systematic collectionofdata, the IHTT investigatorswill study the role of obesity and vitaminA in the etiology of IIH, characterize themyriad of signs and symptoms that occur in these patients, anddetermine the effects of this disorder on quality of life. Theywill evaluate the results of visual field testing at presentation and over time. Ultimately, they will determine the true effects of optimal noninvasive treatments (diet and diuretics) and carefully determine the role of ocular coherence tomography (OCT) in the identification and follow-up of patients with papillema. The article highlights patient characteristics and symptoms and the reader is encouraged to carefully consider this informative report; the importance of the anticipated, aswell asunanticipated, findings; andwhatmight be expected to come from this trial over time. The trial is the workofNORDIC (Neuro-OphthalmologyResearchDisease Investigator Consortium),3 a group of investigators who have come together as a powerful research consortium for this and other clinical trials—now and in the future. The typical patientwith IIH, a condition that affects 20 in 100 000 obese young adult women,4 is generally easily recognized andaccuratelydiagnosed. In addition, general guidelines exist to informmanagementwithweight loss anddiuretics and the critical role of serial visual field testing in following upthesepatients.Despite theseguidelines, 10%ofpatientsend upeffectively blind in 1 eye.5,6 A recentCochraneDatabase reviewremindsus that therehadbeennoprospective, large,multicenter, double-blind, placebo-controlled trials studying this disorder.7 Our knowledge concerning the etiology, signs and symptoms, andmanagementof this condition is largely based on retrospective series and anecdotal reports. To my knowledge, 4 studies to date have looked at patients prospectively,5,8-10 with only 1 attempting a prospective treatment trial.8 In this feasibility study, 50 patients were enrolled and acetazolamidewas comparedwithno treatment, althoughno strict randomizationwasdonebasedonvision losscriteria.The study reported challenges with patient enrollment and recommended that, in future trials, a composite score based on both visual fields and optic disc photographs be used to compare treatment groups.8 The IIHTT is long overdue. This initial publication from the IIHTT Study Group2 reports on a large prospective cohort of untreated patientswith IIH inaneffort tocharacterize thediseaseandassociatedsymptomsandexaminationfindings.Withparticipantsstrictlymeeting the modified Dandy criteria for the diagnosis of IIH and being recruited from38different sites across the country, this study certainly represents the largest group of patients with this condition that has ever been studied with such strict screening and enrollment criteria. Because the cohort of patients being studied has been enrolled in a treatment trial for patients with mild vision loss, the patients described in this report are necessarily skewed toward thosewho have less severedisease. In fact, somewhat surprisingwas the rate ofnonenrollment in the study,which included a significant number of patients whose visual field loss was outside of the range of eligibility, clearly indicating that future studies must be directed at patients with more severe disease. The authors pointed out the striking female preponderance of their study group. Only 4 of the 165 patients were men, causing the authors to question whether this condition really exists in men and continue their search for a risk factor or disease etiology that is unique to women. Typical findings that were expected, of course, were the patients being young adults and the vast majority being obese, with an average bodymass index (calculatedasweight inkilogramsdividedbyheight inmeters squared)of approximately40.Asexpected, themost commonsymptomswereheadache, transient visual obscurations, andpulsatile tinnitus.Asomewhatunexpected findingwas the highprevalence of backpain (53%), a symptom thatmayhave been previously underreported or dismissed. Related article Opinion