Idiopathic Intracranial Hypertension Treatment Trial

Clinical Phase: Phase II Investigators: NORDIC Network sites Study Centers: 38 study centers Coordinating Center - University of Rochester Statistical Center - University of Rochester Study Period Planned enrollment duration: 2 years Planned duration of treatment: 6 months followed by open-label treatment Planned duration of follow-up: 4.5 years Study Objectives: The primary objective is determining the efficacy of diet plus acetazolamide vs diet alone in reducing or reversing visual loss in subjects with mild visual loss.

The secondary objective is to identify proteomic and genetic risk factors for IIH by screening a large cohort of IIH patients and controls.

Study Population This project will enroll 166 individuals with IIH who are 18-60 years of age. We anticipate that the population will be primarily composed of women in the childbearing years that are overweight. 154 control subjects will also be enrolled. Control subjects will be matched as closely as possibly by age, sex, race, ethnicity and weight to subjects enrolled at the site.

Study Design: Multi-center, double-blind randomized intervention study followed by a 4-year observation period. Subjects will be randomized to diet and acetazolamide or diet and placebo. The study will use 250 mg acetazolamide or matching placebo tablets taken with food at meals and at bedtime. The subject will begin with one tablet four times daily, at meals and at bedtime for the first week. Beginning on Day 7, subjects will increase the dosage by 1 tablet every 4 days until a final dosage of 4 tablets four times daily (4 grams) is reached or side effects prohibit increasing the dosage further. If the study drug is not tolerated at a dose of 250 mg, then 125 mg (1/2 tablet) will be tried. If this is not tolerated, no pharmacologic treatment will be given.

After the 6 month visit, all subjects will transition from study medication to acetazolamide (open label) by replacing one tablet of study drug with 250 mg of acetazolamide every four days. The acetazolamide dose will be titrated in a manner similar to the initial study drug schedule to the maximum tolerated dose of acetazolamide. To avoid treating subjects (who may have initially been assigned to placebo) unnecessarily, any subject with grade 0-1 papilledema will be tapered off study drug but not placed on acetazolamide unless they have persisting headaches or pulse-synchronous tinnitus. If so, they will be placed on acetazolamide regardless of the low papilledema grade. At the 9-month follow-up visit, we will make sure that the subjects' vision is stable after the transition off of study medication. After the 9 month visit, medication will be prescribed by the subject's treating physician. The intervention phase of the study will end at the subject's 12 month visit and subjects will be invited to participate in the observational phase of the study and consented to do so if willing.

Number of Subjects: 166 subjects with IIH and 154 control subjects Main Inclusion Criteria

1. Diagnosis of IIH by modified Dandy criteria

2. Diagnosis of IIH for 6 weeks or less

3. Age 18 to 60 years at time of diagnosis

4. Reproducible visual loss present on automated perimetry (in eye with greatest loss)*

5. perimetric mean deviation (PMD) -2 decibel (dB) up to -5 dB in the worst eye

6. Presence of bilateral papilledema

7. Able to provide informed consent or parental permission with appropriate assent

Main Exclusion Criteria

1. Total treatment of IIH of more than one week in the past six weeks

2. Corticosteroids or surgery used for IIH treatment within the past two months

3. Abnormalities on neurologic examination aside from papilledema and its related visual loss or VI nerve paresis (unless pre-existing and unrelated to IIH)

4. Abnormal CT or MRI scan (intracranial mass, hydrocephalus, dural sinus thrombus or arteriovenous malformation) other than empty sella, dilated optic nerve sheath, flattened sclera, or secondary Chiari

5. CSF pressure less than 200 mm water (patients may have repeat CSF pressure measurements if the first is normal or no opening pressure obtained)

6. Abnormal CSF contents (increased cells, elevated protein, low glucose)

7. Intraocular pressure currently > 28 mm Hg or > 30 mm Hg at any time in the past

8. Refractive error > +/- 6.00 sphere or > +/- 3.00 cylinder in either eye

9. Other disorders causing visual loss except for refractive error and amblyopia including cells in the vitreous or iritis

10. Inability to provide reliable and reproducible visual field examination (failure to maintain fixation using an eye monitoring device, more than 15% false positive errors

11. Abnormal blood work-up indicating a medical or systemic condition associated with raised intracranial pressure (ICP)

12. Exposure to a drug, substance or disorder that has been associated with elevation of intracranial pressure within 2 months of diagnosis such as lithium, vitamin A, tetracycline, steroid withdrawal (see table in Manual of Procedures (MOP) for conditions and drugs)

13. Other condition requiring diuretics, steroids or other pressure lowering agents including topiramate

14. Presence of a medical condition such as renal stones that would contraindicate use of the study drugs (acetazolamide)

15. Pregnancy or unwillingness for subject with childbearing potential to use contraception during the first year of the study

16. Presence of a physical, mental, or social condition likely to affect follow-up (drug addiction, terminal illness, no telephone, homeless)

17. Anticipation of a move from the site area within six months and unwillingness to return for follow-up.

Route and Dosage Form: 250 mg acetazolamide tablets or matching placebo taken with food 4 times daily. Subjects will titrate to a maximum dose of 4 tablets 4 times daily (4 grams) as tolerated. If a subject is not able to tolerate a dose of 250 mg, 125 mg (1/2 tablet) may be tried. If this is not tolerated, no pharmacologic treatment will be given.

Duration of Treatment: 6 months of randomized treatment followed by open label acetazolamide treatment. After the 9-month visit medication will be prescribed by the subject's treating physician. The intervention phase of the study will end at Month 12 and the subject invited to continue in the observational phase.

Primary Outcome Measure(s): The primary outcome measure is the change from baseline to Month 6 in PMD (perimetric mean deviation) in the eye with the most severe initial visual loss.

Secondary Outcome Measure: CSF pressure measurement by lumbar puncture Number of abnormal perimetry test locations Visual field examination ratings (improved, remained the same, or worsened) Papilledema grade QOL assessments Dietary Outcomes (BMI, Waist circumference, urinary sodium) Safety Outcomes: Adverse events will be tabulated by treatment group, severity, and perceived relationship to the study intervention Sample Size Considerations