We welcome Dr. Brenner's hypothesis regarding the mechanisms of how weight loss reduces intracranial pressure (ICP). Bariatric surgery has been shown to significantly reduce ICP in association with the amount of weight loss, in IIH,1 which is most notable after Roux-En-Y Gastric Bypass (RYGB).2
Another potential mechanism is regarding the gut neuropeptide glucagon-like peptide-1 (GLP-1), which promotes satiety and weight loss. After RYBG, the bypassed food in the mid/distal jejunum exposes L-cells to nutrients and results in a sharp rise in GLP-1, oxyntomodulin, and peptide YY. Early improvements in glycemic control at 2 weeks post-RYGB in type 2 diabetes mellitus were linked to increased postprandial GLP-1, oxyntomodulin, and peptide YY secretion.3
We observed that ICP was rapidly reduced after bariatric surgery, which seemed to be independent of weight loss, because only relatively small changes in body weight occurred within 2 weeks.1,2 Exenatide, a GLP-1 receptor agonist, directly reduces the CSF secretion and ICP in vivo. A randomized controlled trial demonstrated that exenatide significantly reduced ICP in active IIH at 2.5 hours, 24 hours, and 12 weeks.4 Therefore, we believe the reduction in ICP observed at 2 weeks could be driven by GLP-1 and has the potential—after further investigation—to rival the current surgical practices to save vision in fulminant IIH.
Footnotes
Contributor Information
Susan P. Mollan, (Birmingham, England)
Alex J. Sinclair, (Birmingham, England)
References
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