MTrP needling in GP 2023

Inspired by Yehoshua et al 2023.[1]

MTrP – myofascial trigger point
TrP – trigger point
DN – dry needling (mostly MTrP or TrP needling)
GP – general practice or general practitioner (whichever is contextually relevant)
MPS – myofascial pain syndrome
SF-MPQ – Short-Form McGill Pain Questionnaire
VAS – visual analogue scale
SD – standard deviation of the mean
OR – odds ratio
CI – confidence interval

key to acronyms

This is a small (n=50) prospective cohort study from a general practice based in Israel. Two GPs trained in DN invited patients presenting to the practice with acute MPS to participate in the study – one was described as a specialist who had been in the GP practice for 8 years and performed DN for 3 years and the other was described as a resident who had been in the GP practice for 1 year and had performed DN for 4 years. Whether or not the patients agreed to take part, they were still offered DN as a treatment. If they agreed, all they had to do was to fill in the SF-MPQ before treatment, 10 minutes after, and again at 1 week.[2]

Unsurprisingly, pain scores reduced by 10 minutes and again further by 1 week. As an example, the VAS reduced from a mean of 6.0 at baseline to 4.1 at 10 minutes and to 2.6 at 1 week. 2.6 seems a lot from my memory of treating acute MPS as a military GP. Most of these cases would report that their pain disappeared within a few hours. But this is a comment from memory rather than data from a well reported prospective cohort, which eradicates the problems of biased memories. Also, the population is likely to be a little different.

I should note that the SD was greater than the mean VAS at 1 week (2.6±2.71), meaning that a good proportion of the patients had no pain at all, since none of them could possibly have recorded a negative pain score.

A single needle was used in 77% of treatments, and the 3 most commonly treated muscles were trapezius (40%), iliocostalis lumborum (27.3%) and latissimus dorsi (12.7%). The resident physician performed almost twice as many procedures as the specialist physician (34 vs 18 respectively).

I think the most interesting results of this study come from the multivariate regression analysis, which examined factors related to successful outcomes. Success was determined by improvement in at least 2 of the 3 measures that are part of the SF-MPQ and was determined for short-term (baseline to 10 minutes), medium-term (baseline to 1 week) and continuous success (both short- and medium-term success).

Short-term success was associated with the physician performing the procedure (OR 10.08 CI 1.15, 88.4) and the use of a single needle (OR 4.55 CI 1.03, 20.11). Medium-term success was associated with being born in Israel rather than elsewhere (OR 8.59 CI 1.11, 66.28) and having a high level of initial pain (OR 11.22 CI 1.82, 69.27). Continuous success was associated with use of a single needle compared with multiple needles (OR 5.00 CI 0.97, 25.77).

Use of a single needle as opposed to multiple needles seems likely to indicate discrete acute MPS rather than the possibility of multiple secondary TrPs related to a primary pain source, for example, cervical facet joint pain. The difference between physicians is more difficult to speculate without knowing them or seeing them practice. The authors suggest that the difference is likely to be related to continuity of care. Whilst both had similar experience in DN, the specialist had been in the same GP practice for 8 years and was therefore well known to the patients. I think this is unlikely and that the difference is more likely to be related to the choice of patients, with the resident being less choosy and less likely to avoid the trickier characters. This is, of course, highly speculative.

Gender presumably did not have an influence since this was noted along with country of birth in the baseline characteristic. The same applies to socioeconomic, marital, and smoking status.

I like the method used here. I don’t recall seeing multivariate regression analysis used in a cohort study like this before. I think it would be very interesting to copy and improve the method on a larger scale to narrow down the CIs and get a better idea of the factors associated with success in this primary care population.

References

1          Yehoshua I, Rimon O, Mizrahi Reuveni M, et al. Dry needling for the treatment of acute myofascial pain syndrome in general practitioners’ clinics: a cohort study. BMC Prim Care 2022;23:339. doi:10.1186/s12875-022-01951-0

2          Melzack R. The short-form McGill Pain Questionnaire. Pain 1987;30:191–7. doi:10.1016/0304-3959(87)91074-8