Association of Amount of Weight Lost After Bariatric Surgery With Intracranial Pressure in Women With Idiopathic Intracranial Hypertension

Abstract

Background and objectives: The idiopathic intracranial hypertension randomized controlled weight trial (IIH:WT) established that weight loss through bariatric surgery significantly reduced intracranial pressure when compared with a community weight management intervention. This substudy aimed to evaluate the amount of weight loss required to reduce intracranial pressure and to explore the effect of different bariatric surgical approaches.

Methods: IIH:WT was a multicenter randomized controlled trial. Adult women with active idiopathic intracranial hypertension and a body mass index ≥35 kg/m2 were randomized to bariatric surgery or a community weight management intervention (1:1). This per-protocol analysis evaluated the relationship between intracranial pressure, weight loss, and the weight loss methods. A linear hierarchical regression model was used to fit the trial outcomes, adjusted for time, treatment arm, and weight.

Results: Sixty-six women were included, of whom 23 had received bariatric surgery by 12 months; the mean age was 31 (SD 8.7) years in the bariatric surgery group and 33.2 (SD 7.4) years in the dietary group. Baseline weight and intracranial pressure were similar in both groups with a mean weight of 119.5 (SD 24.1) and 117.9 (SD 19.5) kg and mean lumbar puncture opening pressure of 34.4 (SD 6.3) and 34.9 (SD 5.3) cmCSF in the bariatric surgery and dietary groups, respectively. Weight loss was significantly associated with reduction in intracranial pressure (R2 = 0.4734, p ≤ 0.0001). Twenty-four percentage of weight loss (weight loss of 13.3 kg [SD 1.76]) was associated with disease remission (intracranial pressure [ICP] ≤ 25 cmCSF). Roux-en-Y gastric bypass achieved greater, more rapid, and sustained ICP reduction compared with other methods.

Discussion: The greater the weight loss, the greater the reduction in ICP was documented. Twenty four percentage of weight loss was associated with disease remission. Such magnitude of weight loss was unlikely to be achieved without bariatric surgery, and hence, consideration of referral to a bariatric surgery program early for those with active idiopathic intracranial hypertension may be appropriate.

Trial registration: ClinicalTrials.gov Identifier: NCT02124486; ISRCTN registry number ISRCTN40152829; doi.org/10.1186/ISRCTN40152829.

Classification of evidence: This study provides Class II evidence that weight loss after bariatric surgery results in reduction in intracranial pressure in adult women with idiopathic intracranial hypertension. This study is Class II because of the use of a per-protocol analysis.

Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

Figures

Figure 1. Reduced Body Weight Significantly Correlates With Reduced ICP

(A, B) Linear regression analysis plotting change in body weight against change in ICP at 12 and 24 months postbaseline. (C, D) ICP levels of patients categorized according to percentage and absolute weight loss at 12 months since baseline measurements. The dashed red line indicates the idiopathic intracranial hypertension diagnostic threshold of an ICP >25 cmCSF. Data presented as mean ± SEM. Statistical significance was determined by ordinary 1-way analysis of variance with the Tukey multiple comparisons test. CWI = community weight management intervention; ICP = intracranial pressure.

Figure 2. Surgical Intervention is Significantly More Efficacious at Lowering Body Weight and ICP Than Diet Weight Loss Intervention

Percentage change in diet and surgery groups at baseline, 12-month, and 24-month timepoints for (A) body weight; (B) intracranial pressure; (C) papilledema as measured by OCT volume central thickness; (D) monthly headache days; (E) headache severity; and (F) HIT-6 score; data presented as mean ± SEM. Statistical significance was determined by hierarchical regression modeling in accordance with per-protocol analysis. ***p < 0.001. CWI = community weight management intervention; HIT-6 = headache impact test-6; ICP = intracranial pressure; OCT = optical coherence tomography.

Figure 3. Model-Generated Expected ICP Outcomes for Three Notional Participants With Baseline Weights of 150 kg (Top Line), 120 kg (Middle) and 90 kg (Bottom), Allocated to Each Treatment Arm Under 4 Different Weight Loss Scenarios

The expected ICP values are predicted by a hierarchical model fit to the trial outcomes, adjusted for time, intervention, and contemporaneous weight. CWI = community weight management intervention; ICP = intracranial pressure; p.a. = per annum.