Patients with chronic abdominal wall pain (AWP) had clinical improvement of pain following ultrasound-guided trigger point injection (TPI) therapy. These findings from a randomized trial were published in Pain.
Patients (N=60) with AWP were recruited at the Mayo Clinic Pain Clinic between 2013 and 2019. Patients were randomly assigned in a 1:1 ratio to receive TPI with bupivacaine and triamcinolone (n=30) or ultrasound-guided transversus abdominis plane (TAP) block (n=30). Pain intensity was assessed by the 11-point numerical rating scale (NRS), symptoms of depression by the Center for Epidemiologic Studies-Depression scale (CES-D), and negative cognitive consequences from pain by the Pain Catastrophizing Scale (PCS).
Patients in the TPI and TAP cohorts had a mean age of 52.8 years (±16.1) and 47.0 years (±14.8), 70% and 80% were women, and 73% and 70% had experienced pain for longer than 12 months, respectively. Each cohort was 93% White.
At 30 minutes after TPI or TAP procedures, 70% (95% CI, 0.52-0.83) and 57% (95% CI, 0.39-0.74) of participants reported a 50% or greater reduction in pain (P =.284), respectively.
At 3 months, the TPI recipients reported pain as an NRS score of 2.3 (±2.5), which was significantly lower than the NRS score of TAP recipients (4.0±2.6; Cohen’s d, 0.67; P =.013). Both the intention-to-treat (group difference, 1.7; 95% CI, 0.3-3.0) and the per-protocol (group difference, 1.8; 95% CI, 0.4-3.2) analyses found a medium-sized treatment effect.
No significant associations were observed between 3-month pain scores and baseline CES-D scores (b, 0.02; 95% CI, -0.07 to 0.10) nor with baseline PCS scores (b, 0.01; 95% CI, -0.05 to 0.06).
Procedure-related complications were not observed immediately after TPIs or TAP blocks or at the follow-up assessment.
This study may have been limited by excluding patients with surgical or other causes of AWP and it remains unclear whether a more broad population of patients with AWP may benefit from TPI.
These findings indicated that ultrasound-guided TPI reduced pain immediately after and up to 3 months compared with patients receiving TAP blocks. Patients receiving TAP blocks, however, also reported significantly improved pain scores.
Moeschler SM, Pollard EM, Pingree MJ, et al. Ultrasound-guided transversus abdominis plane block vs. trigger point injections for chronic abdominal wall pain: a randomized clinical trial. Published online January 5, 2021. Pain. doi:10.1097/j.pain.0000000000002181