Lesson 1 of 6
Indication and expected benefit
What 60-day medial branch PNS treats, what the trials found, and how firm that evidence is.
An open-coil lead is placed beside the lumbar medial branch, usually one on each side, at the level in the centre of the axial pain (Gilmore 2021, p. 879). It stimulates for up to 60 days and is then pulled out by gentle traction (Gilmore 2021, pp. 879–880). The intended response is a comfortable, cyclical multifidus contraction, with a comfortable sensation over the painful area (Gilmore 2021, pp. 879–880; McCormick 2026, p. 464).
The lumbar studies treated chronic axial low back pain without radicular leg pain (Gilmore 2021, p. 879), including pain that persisted or returned after radiofrequency ablation (Deer 2021, p. 550). The device is cleared for up to 60 days for chronic intractable pain and for post-surgical and post-traumatic pain (SPR Therapeutics 2022, p. 6).
In the multicentre case series, of 74 participants who reached the 2-month endpoint, 73 % had at least 30 % less average pain and 43 % at least 50 % (Gilmore 2021, p. 883). Of the 62 seen at 14 months, 58 % had at least 30 % pain relief, and 77 % a meaningful gain in pain, disability (a 10-point Oswestry fall) or interference; counting missing data as failure, 59 % (Gilmore 2023, pp. 3–5).
The RESET trial randomised 230 patients to 60-day PNS or physician-directed usual care with standard interventions. At 3 months, 55 % with PNS and 26 % with usual care had at least 50 % relief (McCormick 2026, p. 470), and mean pain stayed lower at 6 months (McCormick 2026, p. 467). Blinding was not possible, and the PNS group may have had higher expectations (McCormick 2026, p. 471). It was funded mainly by the Department of Defense, with additional funding from the device sponsor (McCormick 2026, p. 472).
Longer follow-up comes from surveys of earlier responders: 65 % of 23 respondents reported at least 30 % relief an average 4.7 years after treatment (Gilmore 2025, p. 1104), and 79 % of 602 surveyed patients, who had to have reported at least 50 % relief at the end of treatment, had no later ablation, permanent neurostimulator or low back surgery (Sheth 2026, pp. 1345–1347). They describe responders who answered, not every patient treated.
Benefit and risk
Benefit
- Pain
At least 50 % relief at 3 months: 55 % with PNS, 26 % with usual care (McCormick 2026, p. 470).
- Function
At least 30 % improvement in Oswestry disability at 3 months: 70 % with PNS, 47 % with usual care (McCormick 2026, p. 470).
- Nothing ablated
The lead is removed by gentle traction after up to 60 days (Gilmore 2021, p. 879; McCormick 2026, p. 464).
Risk
- Skin
Mild skin irritation in 31.5 % and itching in 19.8 % at the dressing or pad, and granuloma at 1.4 % of exit sites (McCormick 2026, p. 471); in the case series skin irritation in 28 and itching in 19 of 89 (Gilmore 2021, p. 887).
- Infection
Superficial infection at 2.7 % of lead exit sites (McCormick 2026, p. 471); 2 of 89 in the case series, one at an exit site resolved by removing the lead and an oral antibiotic (Gilmore 2021, pp. 884, 887).
- Pain
New or worse pain or discomfort: 8.1 % and 5.4 % in RESET (McCormick 2026, p. 471); new pain in 6, worse pain in 5 and discomfort in 5 of 89 in the case series (Gilmore 2021, p. 887).
- Lead movement
Four of the 17 participants in the post-ablation study needed a new lead for migration or dislodgement, for example during a bandage change (Deer 2021, pp. 550, 552).
- Lead fracture
A remnant can break off at removal; inspect the lead and decide with the patient whether to retrieve it. A retained remnant limits later MRI to specific conditions (SPR Therapeutics 2022, pp. 12, 40).
- Serious events
No serious or unanticipated adverse events in the case series (Gilmore 2021, p. 884); none serious and unanticipated in RESET, where all study adverse events were mild or moderate (McCormick 2026, pp. 469, 471).