Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension.

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https://radiopaedia.org/articles/idiopathic-intracranial-hypertension-1

Idiopathic Intracranial Hypertension

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A 25-year-old woman with severe obesity presented to the emergency department with a 1-week history of blurred vision, transient visual obscurations, daily headaches, and intermittent whooshing sounds. Her body-mass index (the weight in kilograms divided by the square of the height in meters) was 57. On neurologic examination, optic-disk swelling and retinal hemorrhages were present in both eyes (Panel A, left eye). The results of visual-field and cranial-nerve testing were normal. Magnetic resonance imaging and venography of the head revealed flattened posterior globes with marked elevation of the optic-nerve heads (Panel B, arrows), an empty sella (Panel C, asterisk), and stenoses of the transverse sinuses without obstruction or thromboses — all of which were suggestive of elevated cerebrospinal fluid pressure. A lumbar puncture was notable for an elevated opening pressure of 55 cm of water (reference range, 10 to 20); the results of the cerebrospinal fluid analysis were normal. A diagnosis of idiopathic intracranial hypertension was made. Idiopathic intracranial hypertension is a disorder associated with obesity that manifests with symptoms resulting from increased intracranial pressure, including headaches, diplopia, visual field defects, and pulsatile tinnitus. Treatment with high-dose acetazolamide was started, and counseling on weight loss was provided. At a 1-month follow-up visit, the patient’s papilledema had decreased, and treatment with acetazolamide had been continued.

Effect of Acetazolamide on Visual Function in Patients With Idiopathic Intracranial Hypertension and Mild Visual LossThe Idiopathic Intracranial Hypertension Treatment TrialAcetazolamide for Mild Visual Loss in Intracranial Hypertension Acetazolamide for Mild Visual Loss in Intracranial Hypertension

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The Idiopathic Intracranial Hypertension Treatment Trial

 

Importance  Acetazolamide is commonly used to treat idiopathic intracranial hypertension (IIH), but there is insufficient information to establish an evidence base for its use.

Objective  To determine whether acetazolamide is beneficial in improving vision when added to a low-sodium weight reduction diet in patients with IIH and mild visual loss.

Design, Setting, and Participants  Multicenter, randomized, double-masked, placebo-controlled study of acetazolamide in 165 participants with IIH and mild visual loss who received a low-sodium weight-reduction diet. Participants were enrolled at 38 academic and private practice sites in North America from March 2010 to November 2012 and followed up for 6 months (last visit in June 2013). All participants met the modified Dandy criteria for IIH and had a perimetric mean deviation (PMD) between −2 dB and −7 dB. The mean age was 29 years and all but 4 participants were women.

Interventions  Low-sodium weight-reduction diet plus the maximally tolerated dosage of acetazolamide (up to 4 g/d) or matching placebo for 6 months.

Main Outcomes and Measures  The planned primary outcome variable was the change in PMD from baseline to month 6 in the most affected eye, as measured by Humphrey Field Analyzer. Perimetric mean deviation is a measure of global visual field loss (mean deviation from age-corrected normal values), with a range of 2 to −32 dB; larger negative values indicate greater vision loss. Secondary outcome variables included changes in papilledema grade, quality of life (Visual Function Questionnaire 25 [VFQ-25] and 36-Item Short Form Health Survey), headache disability, and weight at month 6.

Results  The mean improvement in PMD was greater with acetazolamide (1.43 dB, from −3.53 dB at baseline to −2.10 dB at month 6; n = 86) than with placebo (0.71 dB, from −3.53 dB to −2.82 dB; n = 79); the difference was 0.71 dB (95% CI, 0 to 1.43 dB; P = .050). Mean improvements in papilledema grade (acetazolamide: −1.31, from 2.76 to 1.45; placebo: −0.61, from 2.76 to 2.15; treatment effect, −0.70; 95% CI, −0.99 to −0.41; P < .001) and vision-related quality of life as measured by the National Eye Institute VFQ-25 (acetazolamide: 8.33, from 82.97 to 91.30; placebo: 1.98, from 82.97 to 84.95; treatment effect, 6.35; 95% CI, 2.22 to 10.47; P = .003) and its 10-item neuro-ophthalmic supplement (acetazolamide: 9.82, from 75.45 to 85.27; placebo: 1.59, from 75.45 to 77.04; treatment effect, 8.23; 95% CI, 3.89 to 12.56; P < .001) were also observed with acetazolamide. Participants assigned to acetazolamide also experienced a reduction in weight (acetazolamide: −7.50 kg, from 107.72 kg to 100.22 kg; placebo: −3.45 kg, from 107.72 kg to 104.27 kg; treatment effect, −4.05 kg, 95% CI, −6.27 to −1.83 kg; P < .001).

Conclusions and Relevance  In patients with IIH and mild visual loss, the use of acetazolamide with a low-sodium weight-reduction diet compared with diet alone resulted in modest improvement in visual field function. The clinical importance of this improvement remains to be determined.