Percutaneous peripheral nerve stimulation for chronic pain in subacromial impingement syndrome: a case series

Abstract

Objective: The objective of this study was to determine the effect of peripheral nerve stimulation (PNS) on pain reduction for those with refractory subacromial impingement syndrome (SIS) and to evaluate the association with reduced disability, impairment, and safety. Our hypotheses are that PNS will be associated with a reduction in pain, impairment and disability, and improvement in quality of life while demonstrating safety.

Material and methods: Adults with shoulder pain of at least six months duration were recruited for a three-week treatment of percutaneous PNS applied through a percutaneous electrode to the axillary motor points of the deltoid muscle. Subjects were followed for 12 weeks after treatment. The primary outcome was the worst pain in the last week, and secondary outcomes included pain interference, the Disabilities of the Arm, Shoulder, and Hand questionnaire, shoulder abduction range of motion, and safety. Analysis was with a linear mixed model.

Results: Ten subjects were recruited. Longitudinal analysis demonstrated significant reduction in pain relative to baseline (F(1, 66) = 12.9, p < 0.01). After correcting for multiple comparisons, there were significant reductions at explantation and all follow-up time points when compared with baseline. There were also significant improvements in pain interference (F(1,65) = 15.0, p < 0.01), the Disabilities of the Arm, Shoulder, and Hand questionnaire (F(1,35) = 7.0, p = 0.01), and shoulder abduction range of motion (F(1,35) = 6.3, p = 0.02).

Conclusion: Intramuscular PNS for chronic shoulder pain due to SIS is a safe treatment associated with pain reduction, lower pain interference with activities of daily living, reduced disability, and improved shoulder abduction. Pain reduction is maintained for at least 12 weeks after treatment.

Keywords: Chronic pain; electrode placement; nonmalignant pain; percutaneous nerve stimulation; peripheral nerve stimulation.

Conflict of interest statement

CONFLICT OF INTEREST:

Richard D. Wilson is a consultant to SPR Therapeutics, LLC. Maria Bennett is an employee of and owns equity in SPR Therapeutics, LLC. John Chae is a consultant and Chief Medical Advisor to SPR Therapeutics, LLC. Dr. Chae owns equity in SPR Therapeutics, LLC.

Dr. Chae and Mrs. Bennett are patent holders for intramuscular peripheral nerve stimulation for the treatment of chronic pain. SPR Therapeutics, LLC. has a commercial interest in the device presented in this manuscript.

© 2014 International Neuromodulation Society.

Figures

Figure 1

Percutaneous IM PNS Smartpatch™ System. Top: Percutaneous IM Electrode loaded in a 20-gauge introducer. Bottom left: External stimulator mounted on the pad (anode electrode-embedded battery). Bottom right: Configuration on participant.

Figure 2

Worst Pain in the Last Week (0-10), BPI-SF3. Longitudinal analysis revealed a significant changed over time (BPI-SF3, F(1, 66)=12.9, p

Figure 3

Patient Global Impression of Change Scale. Participants rated how much their quality of life has changed since the beginning of the study to end of treatment (EOT) and at the end of the follow period (Week 16).

Figure 4

4a (unaffected shoulder), 4b (affected shoulder), 4c (tibialis anterior). Pressure Pain Thresholds (PPT) of responders (2pt or 30% reduction at end of treatment) compared to non-responders. The period of stimulation is represented by the shaded area.

Figure 4

4a (unaffected shoulder), 4b (affected shoulder), 4c (tibialis anterior). Pressure Pain Thresholds (PPT) of responders (2pt or 30% reduction at end of treatment) compared to non-responders. The period of stimulation is represented by the shaded area.

Figure 4

4a (unaffected shoulder), 4b (affected shoulder), 4c (tibialis anterior). Pressure Pain Thresholds (PPT) of responders (2pt or 30% reduction at end of treatment) compared to non-responders. The period of stimulation is represented by the shaded area.