Stimulated by Lee et al 2023.[1]
Photo by Jonny Goerend on Unsplash, with the cover of SJPAIN superimposed in the bottom right.
PCP – post cholecystectomy pain
key to acronyms
CABG – coronary artery bypass graft
AMPS – abdominal myofascial pain syndrome
TPI – trigger point injection
PRF – pulsed radiofrequency
US – ultrasound
LA – local anaesthetic
NRS – numerical rating scale
EA – electroacupuncture
This paper came up on my myofascial pain search the other day. I don’t recall highlighting a paper from the Scandinavian Journal of Pain (SJPAIN) before, so I thought I would have a look and got stopped by a paywall. Fortunately, Jens was able to get me around it, thanks Jens.
SJPAIN is relatively young, having started life at the end of 2009, and it currently has an impact factor of 1.6, but that will no doubt be on the way up.
I was interested to see the authors are from Leicester, and I vaguely recognised the name of the last author. His name has come up before on my searches for myofascial pain. As well as myofascial pain, acupuncture also gets a small mention in one of his previous papers (more on that further down).[2]
On checking the back catalogue of the blog, I found that I had come across the last author before, and one of his previous papers was also in SJPAIN – see Abdominal TrPs.[3,4]
The current highlighted paper was a prospective observational study that was badged as service evaluation, so it did not require ethics approval. Over a 6-month period, 200 patients who were undergoing laparoscopic cholecystectomy at a single tertiary care centre were assessed for participation. Both elective and emergency procedures were included. Eleven were excluded – 6 converted to open surgery, 4 had learning difficulties, and 1 did not give consent. Of the 189 included for telephone review at 3, 6, and 12 months, a further 12 were lost to follow (6.6%), which is not too bad.
The study was primarily aimed at assessing the incidence of poorly controlled postoperative pain relief in the first 2 days after surgery as well as patient satisfaction with postoperative pain management, but it also assessed the incidence of persistent pain at 3, 6, and 12 months.
I found a review paper by the last author from 2011, which includes a table of the incidence of persistent postoperative pain from a number of different surgical procedures from studies with reasonably good design.[5] Top of the list was thoracotomy (52%), followed closely by mastectomy (48%), pelvic trauma (48%), and CABG (44%). I was surprised to see the incidence of persistent pain following amputation listed as 27-30%, but the authors note that estimates of incidence vary widely, and in the text they include a higher range (50-85%).
Back to PCP and in the present study the incidence of persistent postoperative pain at 12 months was 29%. Of this group (n=54), more than half were found to have a somatic source (AMPS).
AMPS is clearly an area of interest for this group in Leicester and in particular for the last author who published the results of a prospective series of 120 cases of AMPS in 2018.[2] This time it was badged as an audit rather than a service evaluation.
It is a useful paper that follows a large series of patients through a graded set of treatments from medical management including acupuncture, through image guided TPI, to PRF.
It is interesting to note that acupuncture was dismissed relatively early because 4 sessions did not result in any of the first 25 patients having pain relief that lasted over 4 weeks. Unfortunately, there is no detail regarding the specifics of the acupuncture treatment.
TPI was guided by US and used pain recognition as well as the US appearance, which is good. Initially LA alone was used and then this progressed to the addition of steroids. Finally, if sufficient pain relief was not achieved, the last step was PRF, and this was again image guided with US. Niraj has published letters of both US guided TPI and PRF in the past.[6,7]
So, in this AMPS series of 120 patients, medical management was successful in 7 and LA TPI gave no long term relief in 30. Of 104 that went on to steroid and LA TPI, 32% were considered durable responders (4-point change on NRS at 3 months and 2-point change at 6 months – worst pain in last 24 hours). Of the 43 that went on to PRF, 60% were considered durable responders.
Just to finish off on an upbeat note for fellow acupuncturists, an interventional anaesthetist colleague of mine who has been using acupuncture and PRF for a number of years, considers PRF to be a very expensive form of EA.
References
1 Lee H, Askar A, Makanji D, et al. The incidence of post cholecystectomy pain (PCP) syndrome at 12 months following laparoscopic cholecystectomy: a prospective evaluation in 200 patients. Scand J Pain. Published Online First: 29 September 2023. doi: 10.1515/sjpain-2023-0067
2 Niraj G. Pathophysiology and Management of Abdominal Myofascial Pain Syndrome (AMPS): A Three-Year Prospective Audit of a Management Pathway in 120 Patients. Pain Med. 2018;19:2256–66.
3 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.
4 Niraj G, Richards CJ. Leiomyosarcoma of the small intestine presenting as abdominal myofascial pain syndrome (AMPS): case report. Scand J Pain. 2021;21:191–3.
5 Niraj G, Rowbotham DJ. Persistent postoperative pain: where are we now? Br J Anaesth. 2011;107:25–9.
6 Niraj G, Collett BJ, Bone M. Ultrasound-guided trigger point injection: first description of changes visible on ultrasound scanning in the muscle containing the trigger point. Br J Anaesth. 2011;107:474–5.
7 Niraj G. Ultrasound-guided pulsed radiofrequency treatment of myofascial pain syndrome: a case series. Br J Anaesth. 2012;109:645–6.
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