SLR - August 2022 - Tyler Rodericks, DPM
Reference: Ilfeld BM, Plunkett A, Vijjeswarapu AM, Hackworth R, Dhanjal S, Turan A, Cohen SP, Eisenach JC, Griffith S, Hanling S, Sessler DI, Mascha EJ, Yang D, Boggs JW, Wongsarnpigoon A, Gelfand H. Percutaneous Peripheral Nerve Stimulation (Neuromodulation) for Postoperative Pain: A Randomized, Sham-controlled Pilot Study. Anesthesiology. 2021 Jul 1:135(1): 95–110.Level of Evidence: level II
Scientific Literature Review
Reviewed by: Tyler Rodericks, DPM
Residency Program: Mount Auburn Hospital (Cambridge, MA)
Podiatric Relevance: Opioids have been a hallmark of postop pain management for many years, however concern regarding potential for abuse has led to increasing medical and societal sentiment to identify alternative modalities in the acute postoperative setting. Neurostimulation for acute pain management may have the potential to reduce postop opioid consumption while effectively managing patient pain for moderate to major orthopedic surgery.
Methods: This is a double blinded multicenter randomized controlled trial in which 65 patients randomized to either a stimulation or sham group underwent percutaneous implantation of a peripheral nerve stimulator for the treatment of postoperative pain prior to undergoing orthopedic surgery. all patient subsequently received a preoperative regional block with ropivacaine for their anticipated surgical site. A prescription for opioid analgesics was provided to all patients to be taken as needed. Tylenol and NSAID usage/prescription was neither controlled for nor evaluated. Stimulators were all set to a fixed frequency and all patients were allowed to self-regulate intensity. However, the stimulators in the sham group were nonfunctional. Primary outcomes were cumulative PO opioid consumption and a numerical pain scale evaluated on postoperative days 1-4, 7, and 11. Leads were removed at day 14 with further outcomes evaluation continuing on day 15 and months 1 and 4. Secondary outcomes included the brief pain inventory short form and WHO quality of life scale. Primary outcomes were statistically assessed for noninferiority of the treatment group, and subsequently for superiority if primary outcomes were both found to be noninferior. Significance was set to 0.025 for the noninferiority/superiority testing and 0.05 for secondary measures.
Results: There was significantly less cumulative postoperative opioid consumption (5mg vs. 48mg, p=<0.001) and significantly lower numerical pain scores (1.1 vs 3.1, p=<0.001) in the stimulation group than the sham group. The stimulator group was found to be noninferior in both primary outcomes, and subsequently found to be superior in these outcomes. Treatment effect revealed reduced opioid consumption by 80% and pain scores by 50 percent. Patients receiving treatment also reported less emotional and physical interference associated with pain in secondary measures. Few significant differences were found at months 1 and 4 postoperatively between treatment and sham groups. Post hoc assessment of blinding revealed 95 percent of patients either believed they received treatment or did not know which group they were in. Only one patient correctly identified themself to be in the sham group.
Conclusions: The authors concluded that percutaneous peripheral nerve stimulation reduced pain scores and opioid requirements in the first week postoperatively after orthopedic surgery to a statistically and clinically meaningful degree. This has the potential to be very impactful and beneficial to our patients given potentially improved pain management and fewer systemic side effects with neuromodulation compared to opioid pain management postoperatively. While further studies on the topic would be necessary prior to considering a substantial change to a surgeons postoperative pain management protocols, this may represent a potential option for a patient who has been historically refractory or has significant contraindications to other common modalities.