Efficacy of Vagal Blockade For Obesity Treatment Remains VagueThursday, September 18, 2014
Regular readers may recall past posts on the use of intermittent electrical blockade of the vagus nerves (VBLOC) as a means of reducing food intake to promote weight loss.
Now a large randomised controlled study of vagal blocakade, published by Sayeed Ikramuddin and colleagues, published in JAMA, reports on rather disappointing outcomes with this treatment.
In this study (ReCharge), conducted at one of 10 sites in the United States and Australia between May and December 2011, 239 participants with a BMI greater than 40 (or greater than 35 with at least one comorbidity), were randomised to receiving an active vagal nerve block device (EnteroMedics’ Maestro® Rechargeable (RC) System, n=162) or a sham device (n=77).
Over the 12-month blinded portion of the 5-year study (completed in January 2013), the vagal nerve block group lost about 9% or their initial body weight compared to only 6% in the sham group.
In addition to this rather modest difference in weight loss between the groups (about 3%), participants in the active treatment group also experienced a number of clinically relevant adverse effects (heartburn or dyspepsia and abdominal pain).
Thus, overall these rather disappointing results are in line with the previously disappointing observations in the smaller MAESTRO trial.
Based on these findings, it seems that intermittent electrical blockade of the vagal nerve may not hold its promise of a safe and effective long-term treatment for severe obesity after all.
Ikramuddin S, Blackstone RP, Brancatisano A, Toouli J, Shah SN, Wolfe BM, Fujioka K, Maher JW, Swain J, Que FG, Morton JM, Leslie DB, Brancatisano R, Kow L, O’Rourke RW, Deveney C, Takata M, Miller CJ, Knudson MB, Tweden KS, Shikora SA, Sarr MG, & Billington CJ (2014). Effect of reversible intermittent intra-abdominal vagal nerve blockade on morbid obesity: the ReCharge randomized clinical trial. JAMA, 312 (9), 915-22 PMID: 25182100
Thursday, September 18, 2014
I’m not a neurologist and I don’t know a lot of neruobiology, but this seems like a terrible idea to me. I do know that vagal nerve stimulation is used to treat depression. Couldn’t blocking even part of the vagal nerve exacerbate depression (which could increase food intake and lead to weight gain)? I imagine they accounted for this, but isn’t part of the role of the vagus nerve to signal satiety? Wouldn’t inhibiting the vagus nerve work against this? I imagine there are a lot of branches of the vagus nerve and you can stimulate/block branches, but overall I feel like stimulation would be a better mechanism than inhibiting for reducing food intake.