Peripheral nerve stimulation

Peripheral nerve stimulation places a lead next to a named nerve; the 60-day percutaneous approach is a definitive temporary treatment, with its strongest support in post-amputation and phantom limb pain.

1. Define the therapy precisely. Direct PNS stimulates a named nerve and differs from peripheral nerve field stimulation, percutaneous electrical nerve stimulation and TENS, which act indirectly; field stimulation, for example, places subcutaneous leads to spread stimulation across the painful area ¹.
2. Mechanisms are multiple. Proposed actions include gate control, inhibition of A and C fibers with repeated stimulation, effects on inflammatory mediators and endogenous opioids, and central reconditioning ¹.
3. 60-day PNS is not a trial. A percutaneous coiled lead stimulates for about 60 days and is then removed, aiming for relief that outlasts it; ASPN separates this from diagnostic trials and permanent implants ².
4. Amputation pain has the strongest evidence. ASPN gives phantom and residual limb pain a strong, grade A, high-certainty statement, and chronic low back pain with centralized contributions a strong grade A ².
5. The randomized trial was positive. In 28 lower-limb amputees with ultrasound-guided sciatic and femoral leads, 58% receiving PNS versus 14% placebo had at least 50% pain reduction in weeks 1–4 ³.
6. Benefit can persist. After 8 weeks of PNS, 67% had at least 50% pain reduction and 80% had at least 50% less pain interference, versus 14–15% with placebo; four of five patients completing 12-month follow-up reported at least 50% relief ³.

Response to a 60-day course varies: some case series show relief months after lead removal, others a return of pain, after which a permanent system may be placed; set expectations beforehand ².

• Older implanted PNS leads migrated in 9–25% and became infected in 3.6–17.9% of cases ².
• The coiled lead encourages fibrotic ingrowth, reducing migration and infection ².
• A negative diagnostic nerve block does not exclude PNS, because the mechanisms differ ².
• ASPN rates postoperative refractory knee pain as strong, grade B, high certainty ².
• Occipital neuralgia carries a moderate, grade B, low-certainty statement ².
• Direct PNS lead placement needs image guidance with fluoroscopy or ultrasound to avoid fracture and migration ¹.
• PNS has also been reported for anterior cutaneous nerve entrapment syndrome refractory to conservative management ⁴.

• Calling 60-day PNS a screening trial for a permanent implant; it is intended as a definitive course ².
• Equating direct PNS with TENS or field stimulation ¹.
• Requiring a positive diagnostic block before PNS ².
• Treating chronic neck pain as a strong PNS indication; ASPN rates it weak, grade C ².