Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation for the Treatment of Postoperative Pain: The First Efficacy Data from a Randomized, Double-Masked, Sham-Controlled Study Design
Ilfeld BM, Gabriel RA, Said ET, Monahan AM, Sztain JF, Abramson WB, Khatibi B,
Finneran JJ, Jaeger PT, Schwartz AK, Ahmed SS
University California San Diego
•Percutaneous peripheral nerve stimulation (pPNS) or “neuromodulation” is an analgesic modality involving the insertion of an electrical lead through an introducing needle—obviating the requirement of a surgical incision for placement—followed by the introduction of electric current
•Neuromodulation is based on “gate control theory”, in which electric current stimulates large-diameter afferent nerve fibers that subsequently interrupt communication (the “gate”) from small-diameter pain fibers to the central nervous system at the level of the spinal cord.
•This therapy has multiple theoretical benefits over existing analgesic modalities: a lack of systemic side effects (e.g., opioid-induced nausea, respiratory depression), diversion and abuse potential, local anesthetic-induced sensory, motor, and proprioception deficits, and significant foreign body infection risk
•To date, all published reports of pPNS to treat postoperative pain are in the form of short series, and therefore no evidence of efficacy derived from a controlled investigation is available.
•The objective of this pilot study was to provide the first data from an RCT design involving pPNS to treat postoperative pain.
•The protocol was prospectively registered (NCT02898103), approved by the local IRB, and all subjects provided written informed consent. Lead insertion occurred within 2 weeks prior to hallux valgus osteotomy.
•A helically-coiled, insulated electrical lead was percutaneously inserted 1-2 cm posterior to the sciatic nerve between the popliteal fossa and subgluteal region using a short-axis, in-plane ultrasound-guided approach.
•A general anesthetic was administered during surgery and a pulse generator (“stimulator”) was connected to the lead and initiated in the recovery room (SPRINT, SPR Therapeutics, Cleveland, Ohio).
•Subjects received 5 minutes of either stimulation or sham in a randomized, double-masked fashion followed by a 5-minute crossover period, and then continuous stimulation for the following 30 minutes for both treatment groups.
•During the initial 5-minute treatment period, subjects initially randomized to stimulation (n=4) experienced a downward trend in their pain over the 5 minutes of treatment, while those initially receiving sham (n=3) reported no such change until their subsequent 5-minute stimulation crossover (Figure).
•During the subsequent 30 minutes of stimulation pain scores decreased to 52% of baseline for all subjects (n=7).
•There is a “carryover” effect following PNS so that subjects continue to receive a variable duration and degree of analgesia following electrical current discontinuation, possibly due to sustained modification of supraspinal pain processing. We therefore provide this graphed data, but include it in ghost to indicate the uncertainty of its interpretation.
Our results suggest that pPNS is effective in decreasing acute pain following hallux valgus surgery, and that the peak analgesic effect may be at least 40 minutes after the initiation of stimulation.