Osteopathic visceral manipulation: a new study fails to convince anyone

Osteopathic visceral manipulation (OVM) have been our subject several times before. The method has been developed by the French Osteopath and Physical Therapist Jean-Pierre Barral. According to uncounted Internet-sites, books and other promotional literature, OVM is a miracle cure for just about every disease imaginable. Most of us hearing such claims hear alarm bells ringing – rightly so, I think. The evidence for OVM is thin, to put it mildly. But now, there is a new study to consider.

Brazilian researchers designed a placebo-controlled study using placebo visceral manipulation as the control to evaluate the effect of OVM of the stomach and liver on pain, cervical mobility, and electromyographic activity of the upper trapezius (UT) muscle in individuals with nonspecific neck pain (NS-NP) and functional dyspepsia. Twenty-eight NS-NP patients were randomly assigned into two groups: treated with OVM (OVMG; n = 14) and treated with placebo visceral manipulation (PVMG; n = 14). The effects were evaluated immediately and 7 days after treatment through pain, cervical range, and electromyographic activity of the UT muscle.

Visceral manipulation techniques for stomach (a), liver (b), and placebo technique (c).

Significant effects were confirmed immediately after treatment (OVMG and PVMG) for numeric rating scale scores and pain area. Significant increases in EMG amplitude were identified immediately and 7 days after treatment for the OVMG. No differences were identified between the OVMG and the PVMG for cervical range of motion.

The authors concluded that the results of this pilot study indicate that a single session of osteopathic visceral manipulation for the stomach and liver reduces cervical pain and increases the amplitude of the upper trapezius muscle EMG signal immediately and 7 days after treatment in patients with nonspecific neck pain and functional dyspepsia. Patients treated with placebo visceral mobilisation reported a significant decrease in pain immediately after treatment. The effect of this intervention on the cervical range of motion was inconclusive. The results of this study suggest that further investigation is necessary.

There are numerous problems with this study:

• The authors call it a pilot study. Such a trial is for exploring the feasibility of a proper study. With the introduction of a placebo-OVM, this would make sense. The relevant question would then be: is the placebo valid and indistinguishable from the real thing? Sadly, this issue is not even addressed in the trial.
• A pilot study certainly is not for evaluating the effectiveness of an intervention. Sadly, this is precisely what the authors used it for. The label ‘pilot’, it seems, was merely given to excuse the many methodological flaws of their trial.
• For an evaluation of treatment effects, the study was far too small. This means the reported results can be discarded as meaningless.
• If we nevertheless took them seriously, we would want to explain how the findings were generated. The authors believe that they were caused by OVM. I find this most unlikely.
• The more plausible explanation would be that patient-blinding was unsuccessful. In other words, the placebo is not indistinguishable from the real OVM. Looking at the pictures above, one can easily see that the patients were able to tell to which group they had been allocated.
• The failure to blind patients (and, of course, the therapists), in turn, would mean that the verum group were better motivated to out-perform the placebo group in the outcome measures.
• Finally, I disagree with the authors’ view that the results of this study suggest that further investigation is necessary. On the contrary, I think that any further investment into OVM is ill-advised.

My conclusion: OVM is an implausible, non-evidence-based SCAM, and dodgy science is not going to make it look any more convincing.