Abdominal TrPs

Inspired by Mitidieri et al 2020,[1] Niraj et al 2020,[2], Niraj et al 2020,[3] Sangondimath et al 2020,[4] Hasuo et al 2020,[5] Jin et al 2020.[6]

Photo by Dani Alejandro on Pexels.com

TrP – myofascial trigger point
RCT – randomised controlled trial
TPI – trigger point injection
APB – abdominal plane block
MPS – myofascial pain syndrome
SR – systematic review
GTPase – guanidine triphosphate hydrolase

key to acronyms

Well the first three papers are about abdominal myofascial pain, and the last three are tagged on for interest, and are on the theme of TrPs, but are not strictly abdominal…

First up is a small comparative RCT of TrP acupuncture versus TPI in abdominal MPS (n=25). They actually called it ‘Ashi’ acupuncture, but the needles were not manipulated, so it was not strictly TrP dry needling. Having said that, needling the abdominal wall can be more uncomfortable than needling limb and limb girdle muscles, so I am not criticising the approach. A course of 10 weekly sessions of acupuncture at active and latent TrPs was compared with 4 sessions of TPI at active TrPs using 2ml of 1% lidocaine injected with a 22G needle (between 21G – green, and 23G – blue).

Both groups improved with no significant differences between them. The authors concluded that both approaches were effective, but this ignores the possibility of any influence of natural history or context. I scanned the reference list in vain for my first SR, which was on needling therapies in TrP pain, and published nearly 20 years ago. Adrian and I concluded then that it did not matter what was injected, and either the needling worked or it was placebo.[7]

…it didn’t matter what was injected 20 years ago, and it probably doesn’t now!

The second paper comes from the same journal as the first – Pain Physician.[2] It is the official journal of the American Society of Interventional Pain Physicians, and an open access journal. It is an audit of 234 patients with chronic abdominal pain from MPS followed through a management programme in a tertiary care centre. The programme starts with medication, then adds psychological approaches before moving to interventional techniques. The audit demonstrates a reduction in opioid use, and it is based in the UK!

The third paper has the same first author as the second and is a case report that resulted from one of the prior cohort that was subject to the audit.[3] It describes a rather rare presentation of abdominal pain, and is a timely reminder that abdominal MPS can be secondary to serious visceral pathology. In this case it seems that one of the interventional techniques facilitated diagnosis, presumably because it required imaging to guide the intervention, and an intra-abdominal abnormality was spotted.

[Postscript: well having just got the full text of this paper, it was not an imaging finding but acute bowel obstruction, possibly influenced by somatovisceral interactions, or more likely the use of opioids for post-interventional pain.]

…abdominal MPS can be secondary to serious visceral pathology

I guess this last report may represent an unintended advantage of performing an interventional procedure, but we should not lose sight of the possible adverse effects of intervention, and the fourth paper details a very rare complication of TPI – quadriparesis resulting from the mineralocorticoid effect (potassium loss) of injected corticosteroids.[4]

Quadriparesis – a very rare complication of TPI

The fifth paper is a prospective observation study (n=205) of relative TPI efficacy in cancer patients with MPS based on whether or not the MPS was influenced by psychological stress.[5] They used Rivers et al’s criteria for diagnosing MPS, and that led me to review these criteria, which were derived from a survey to which that I am pretty sure I contributed. I will show you those at the blog webinar this week.

Unsurprisingly the response to TPI was better in those for whom stress did not appear to play a part in the MPS (82% versus 55%).

a biopsy study… spiced up with protein microarray analysis

Finally, I have something completely different, but still on the subject of TrPs.[6] This is a biopsy study in humans with TrPs, which has been spiced up with protein microarray analysis to examine what might be going on in the sections of contracted sarcomeres that appear to be prevalent in TrPs. Oh it is complex I’m afraid, involving ephrine receptors (type B) and the Rho family of GTPases! I can sense another epic coming on in the blog webinar on Wednesday.

Reference list

1         Mitidieri AM de S, Baltazar MCDV, da Silva APM, et al. Ashi Acupuncture Versus Local Anesthetic Trigger Point Injections in the Treatment of Abdominal Myofascial Pain Syndrome: A Randomized Clinical Trial. Pain Physician 2020;23:507–18.

2         Niraj G, Alva S. Opioid Reduction and Long-Term Outcomes in Abdominal Myofascial Pain Syndrome (AMPS): A 6-Year Longitudinal Prospective Audit of 207 Patients. Pain Physician 2020;23:E441–50.

3         Niraj G, Richards CJ. Leiomyosarcoma of the small intestine presenting as abdominal myofascial pain syndrome (AMPS): case report. Scand J Pain Published Online First: 24 September 2020. doi:10.1515/sjpain-2020-0099

4         Sangondimath G, Varma Kalidindi KK, Pandrakula P, et al. An unusual complication of quadriparesis after trigger point injection: a case report. Pain Published Online First: 29 September 2020. doi:10.1097/j.pain.0000000000002094

5         Hasuo H, Ishiki H, Matsuoka H, et al. Clinical Characteristics of Myofascial Pain Syndrome with Psychological Stress in Patients with Cancer. J Palliat Med 2020;:jpm.2020.0371. doi:10.1089/jpm.2020.0371

6         Jin F, Guo Y, Wang Z, et al. The pathophysiological nature of sarcomeres in trigger points in patients with myofascial pain syndrome: A preliminary study. Eur J Pain 2020;:ejp.1647. doi:10.1002/ejp.1647

7         Cummings TM, White AR. Needling therapies in the management of myofascial trigger point pain: A systematic review. Arch Phys Med Rehabil 2001;82:986–92. doi:10.1053/apmr.2001.24023

Declaration of interests MC