Stimulated by Baeumler et al 2019.
This paper’s first author is the lovely Petra, who presented at the BMAS Autumn meeting at the Royal Society in 2012. I remember how impressed she was to be surrounded by so many famous busts of scientist heroes. I was busy organising the programme and had not noticed them, although I was of course aware of the prestige of the venue, Allyson’s choice.
I first met Petra at the World Pain Congress in Montreal in 2010. She was one of Dominik Irnich’s team from Munich. Dominik is an anaesthetist and pain specialist who first came to my attention via a phone call from a BMJ editor in 2001. He had submitted a paper, which they had accepted, and they were just checking (with the BMAS) at the last minute, whether the control procedure used was adequate. Since we had just had an international consensus meeting on controls, you can imagine how I waxed lyrical on the subject, and consequently was asked to pen a commentary to accompany the article. On rereading this commentary 18 years on I see that I was way too keen on the then new retractable needles developed by my friend Konrad. Who could tell that they would turn out to be one of the most effective sham techniques ever developed!
Dominik went on to set up an enviable pain programme in Munich that incorporated complementary medicine techniques. It is now called MOCAM, which stands for Munich Outpatient Program in Complementary and Alternative Medicine. I should note at this point, in an attempt to avert confusion, but possibly simply serving to generate it, that the same acronym has been used for an ongoing trial based in the UK.
In recent years, Petra, who is a biomedical scientist, has got her hands on QST (Quantitative Sensory Testing) equipment and started to use it to investigate acupuncture. She started with a review to determine the likely way forward, and then performed a nice experimental study on healthy subjects. She had identified from review of the literature that PPT (pressure pain threshold) was likely to be the best measure for assessing the immediate effects of acupuncture, and then went on to demonstrate that EA (electroacupuncture) had a marked segmental influence on PPT, but that manual acupuncture did not. Nor did either have any immediate effect at a heterotopic location.
The current paper takes a different approach and examines sensory measures that might correlate with the immediate analgesic response to therapeutic acupuncture performed within the MOCAM programme on patients with chronic pain. So this is a prospective observational cohort of 100 patients. They were tested for temporal summation (TS) and vibration detection threshold (VDT) prior to their first acupuncture treatment in the programme. TS measures the degree to which an individual amplifies nociceptive signals if they are repeated in close succession, hence the term temporal. The other form of summation is related to proximity, and thus it is called spacial summation. TS was tested using a fancy modern version of the von Frey hair. The latter was discussed in a previous blog. Basically TS was measured by how much more painful 10 pin pricks were compared with just 1 in the same place. This is called the wind up ratio (WUR). A ratio of 2.5 or above selected out a population with higher than average nociceptive amplification, and in this population there was significantly greater chance of immediate pain relief following acupuncture.
Petra and her colleagues say that their results suggest that patient with high levels of central sensitisation may be more responsive to acupuncture. Given the nature of their data this is speculative, but perhaps, along with Vickers et al, indicates what should be a positive nod in the upcoming NICE chronic pain guidelines.
1 Baeumler PI, Conzen P, Irnich D. High Temporal Summation of Pain Predicts Immediate Analgesic Effect of Acupuncture in Chronic Pain Patients-A Prospective Cohort Study. Front Neurosci 2019;13:498. doi:10.3389/fnins.2019.00498
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7 Bradbury K, Al-Abbadey M, Carnes D, et al. Non-specific mechanisms in orthodox and CAM management of low back pain (MOCAM): theoretical framework and protocol for a prospective cohort study. BMJ Open 2016;6:e012209. doi:10.1136/bmjopen-2016-012209
8 Baeumler PI, Fleckenstein J, Takayama S, et al. Effects of acupuncture on sensory perception: a systematic review and meta-analysis. PLoS One 2014;9:e113731. doi:10.1371/journal.pone.0113731
9 Baeumler PI, Fleckenstein J, Benedikt F, et al. Acupuncture-induced changes of pressure pain threshold are mediated by segmental inhibition–a randomized controlled trial. Pain 2015;156:2245–55. doi:10.1097/j.pain.0000000000000283
10 Vickers AJ, Vertosick EA, Lewith G, et al. Acupuncture for Chronic Pain: Update of an Individual Patient Data Meta-Analysis. J Pain 2017;19:455–74. doi:10.1016/j.jpain.2017.11.005