Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation: Neuromodulation of the Sciatic Nerve for Postoperative Analgesia Following Ambulatory Foot Surgery, a Proof-of-Concept Study

Abstract

Background and objectives: Percutaneous peripheral nerve stimulation (PNS) is an analgesic modality involving the insertion of a lead through an introducing needle followed by the delivery of electric current. This modality has been reported to treat chronic pain as well as postoperative pain the day following knee surgery. However, it remains unknown if this analgesic technique may be used in ambulatory subjects following foot procedures beginning within the recovery room immediately following surgery, and with only short series of patients reported to date, the only available data are derived from strictly observational studies. The purposes of this proof-of-concept study were to demonstrate the feasibility of using percutaneous sciatic nerve PNS to treat postoperative pain following ambulatory foot surgery in the immediate postoperative period and provide the first available data from a randomized controlled study design to provide evidence of analgesic effect.

Methods: Preoperatively, an electrical lead (SPRINT; SPR Therapeutics, Inc, Cleveland, Ohio) was percutaneously inserted posterior to the sciatic nerve between the subgluteal region and bifurcation with ultrasound guidance. Following hallux valgus osteotomy, 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 until lead removal on postoperative days 14 to 28.

Results: During the initial 5-minute treatment period, subjects randomized to stimulation (n = 4) experienced a downward trajectory in their pain over the 5 minutes of treatment, whereas those receiving sham (n = 3) reported no such change until their subsequent 5-minute stimulation crossover. During the subsequent 30 minutes of stimulation, pain scores decreased to 52% of baseline (n = 7). Three subjects (43%) used a continuous popliteal nerve block for rescue analgesia during postoperative days 0 to 3. Overall, resting and dynamic pain scores averaged less than 1 on the numeric rating scale, and opioid use averaged less than 1 tablet daily with active stimulation. One lead dislodged, 2 fractured during use, and 1 fractured during intentional withdrawal.

Conclusions: This proof-of-concept study demonstrates that percutaneous sciatic nerve PNS is feasible for ambulatory foot surgery and suggests that this modality provides analgesia and decreases opioid requirements following hallux valgus procedures. However, lead dislodgement and fracture are concerns.

Clinical trial registration: This study was registered at Clinicaltrials.gov, identifier NCT02898103.

Conflict of interest statement

Conflict of interest: The institution of Drs. Ilfeld, Gabriel, Said, Sztain, Abramson, Khatibi, and Finneran–the University California San Diego (San Diego, CA)–has received funding and/or product for other research studies from SPR Therapeutics (Cleveland, OH).

Figures

FIGURE 1

The PNS equipment used for this study: A 12.5-cm, 20-gauge needle with a preloaded helically coiled monopolar insulated electrical lead (A; MicroLead, SPR Therapeutics, Inc; illustration used with permission from B.M.I.) and a stimulator attached to the surface return electrode (B; SPR Therapeutics, Inc; illustration used with permission from B.M.I.). The power source (battery) for the pulse generator is integrated into the white surface return electrode pad.

FIGURE 2

Effects of PNS of the sciatic nerve on surgical pain within the recovery room immediately following hallux valgus osteotomy. Subjects were randomized to receive 5 minutes of either electric current (“stimulation”; n = 4) or sham (n = 3) in a double-masked fashion (Treatment Period A) followed by a 5-minute crossover period (Treatment Period B). Stimulation was subsequently delivered to all subjects (n = 7) for 30 additional minutes. Data are presented as means at each time point with the original pain scores measured using the NRS. Given the relatively small sample size, statistics were not applied to the data. The group who received stimulation during the initial treatment has data shown in ghost during the subsequent period because peripheral nerve stimulation has a “carryover” effect, and these data points are therefore difficult to interpret.

FIGURE 3

Pain at rest during PNS of the sciatic nerve following hallux valgus osteotomy. Data are presented for each subject (subject A withdrew prior to any data collection). Subject D had a functioning lead for only PODs 4 to 6. This subject and subjects B and E triggered their perineural infusions for at least 10 minutes each of the first 2 PODs, falling to 2 subjects (B and E) on POD 3.

FIGURE 4

Pain with movement during PNS of the sciatic nerve following hallux valgus osteotomy. Data are presented for each subject (subject A withdrew prior to any data collection). Subject D had a functioning lead for only PODs 4 to 6. This subject and subjects B and E triggered their perineural infusions for at least 10 minutes each of the first 2 PODs, falling to 2 subjects (B and E) on POD 3.

FIGURE 5

Opioid consumption during PNS of the sciatic nerve following hallux valgus osteotomy. Data are presented for each subject (subject A withdrew prior to any data collection). Subject D had a functioning lead for only PODs 4 to 6. This subject and subjects B and E triggered their perineural infusions for at least 10 minutes each of the first 2 PODs, falling to 2 subjects (B and E) on POD 3.