Interventional procedure overview of neurostimulation of lumbar muscles for refractory non-specific chronic low back pain

Safety summary

Overall adverse events (related to the procedure, device and/or simulation)

In the RCT of 204 patients, 4% (8/204) device or procedure related serious adverse events were reported within 120-days follow up. Most happened within 30 days and were procedure related (Gilligan 2021).

A total of 76 adverse events were reported in 66% (35/53) of patients in the case series of 53 patients. None of these were classified as serious events. 14 of these events in 21% (11/53) of patients were procedure related, 39 events in 47% (25/53) of patients were device related, 7 events in 9% (5/53) of patients were device or procedure related, and 16 events in 29% (15/53) of patients were simulation related (Deckers 2018).

A prospective case series of 42 patients with chronic mechanical low back pain (CMLBP), implanted with a neurostimulator for contraction of the lumbar multifidus, reported 20 adverse advents related to the procedure, the device, or stimulation across 28.6% (12/42) of patients, 15 of which were resolved. The biggest proportion of events were stimulation related (Thomson 2021).

A total of 97 adverse events were reported in the case series of 28 patients. Of these, 60 were related to the device, the procedure or both (27 device related,13 procedure related and 20 both device and procedure related) and happened in 74% (20/27) of patients (Deckers 2015).

Procedure related adverse events

14 procedure related adverse events (wound pain, inflammation, hematoma, postoperative discomfort) were reported in 21% (11/53) of patients in the case series of 53 patients. 7 events in 9% (5/53) of patients were device or procedure related (seroma or inflammation because of lead incision, and postoperative nervous system irritation). These events happened at rates of 1 to 5% (Deckers 2018).

13 procedure related adverse events (pain [3 events], abnormal healing [1 event], nausea or vomiting related to anaesthesia [1 event], nervous system injury [2 events], musculoskeletal stiffness [2 events], infection [2 events], seroma [1 event], and risk associated with surgery [1 event]) were reported in the case series of 28 patients (Deckers 2015).

In the RCT of 204 patients, 3% (6/204) patients developed a pocket infection (which resolved after device explantation and antibiotic treatment), 1 patient had an intraoperative upper airway obstruction that resolved, and 1 patient developed an ongoing non-radicular patch of numbness on the surface of the thigh (further details were not reported) (Gilligan 2021).

In the case series of 42 patients, 7.1% (3/42) experienced implant site pocket pain, 2.4% (1/42) experienced implant site blisters, 2.4% (1/42) experienced implant site pocked infection and 2.4% (1/42) experienced wound pain (Thomson 2021).

Device related adverse events

39 adverse events in 47% (25/53) of patients were device related (loss of stimulation [23 events], pocket or lead discomfort [13 events] and undesired sensations [3 events]) in the case series of 53 patients (Deckers 2018).

Lead fractures and inadequate stimulation

Lead conductor fractures because of tight bending in 44 leads (implanted using lateral approach) leading to loss of stimulation and high impedance on 1 of the conductors on the stimulation channels was observed in 53% (28/53) of patients in the case series of 53 patients. Thirteen had surgical revision to implant new leads, 7 were reprogrammed to resume bilateral stimulation by a different electrode configuration, 3 had continued therapy with unilateral stimulation, 3 had the system turned off, and 2 had the system explanted. A modified implant procedure using a midline approach reduced the risk of lead bending and conductor fractures (Deckers 2018).

Inadequate stimulation (because of lead migration in 8, high impedance in 2, pulse generator malfunction in 2, reason not specified in 1) was reported in 48% (13/27) of patients in the case series of 28 patients (Deckers 2015).

Lead conductor fractures were reported in 2 patients in the case series of 42 patients; these fractures were resolved in both patients (Thomson 2021).

Over stimulation

Over stimulation of tissue was reported in 11% (3/27) of patients (5 events) in the case series of 28 patients (Decker 2015).

In the case series of 42 patients, 10 events of overstimulation of tissue were reported in 16.7% (7/42) of patients, 7 of which were resolved (Thomson 2021).

Undesired sensations

Undesired sensations in the target or non-target area were reported in 7% (2/27) of patients in the case series of 28 patients (Deckers 2015).

21 events of device or simulation related undesired sensations in the target area, including muscle fatigue, were reported in 29% (15/53) of patients in the case series of 53 patients (Decker 2018).

Lead migration

One lead migration leading to loss of sensation was reported in a patient in the case series of 53 patients (Deckers 2018, Mitchell 2021).

21 lead migrations leading to inadequate stimulation or surgical revision happened in 48% (13/27) of patients in the case series of 28 patients. 5 events happened between implantation and 3‑month follow up. 5 patients had more than 2 migrations, 2 had more than 3 migrations, and 1 had 4 migrations (Deckers 2015).

Other device related events

Pain (5 events), tissue injury and fever in 1 patient each, were reported in the case series of 28 patients (Deckers 2015).

In the case series of 42 patients, 1 patient experienced leg pain (unresolved) and 1 patient experienced a synovial cyst (which was later resolved) (Thomson 2021).

Surgical revisions

In the open label follow up of an RCT, 22.1% (45/204) of patients had a total of 47 surgical interventions. 15.7% (32/204) of systems were removed (with 1/204 systems being reimplanted), 2% (4/204) of implant pulse generators were repositioned and 5% (10/204) of patients had leads replaced. Reasons for device removal were lack of effectiveness (9), infection (6), and as a safety precaution before an MRI scan (4) (Gilligan 2021).

In the case series of 42 patients, 4.7% (2/42) of patients had surgical revisions to replace leads after lead fracture (Thomson 2021).

20 surgical revisions were done in 63% (17/27) of patients in the case series of 28 patients. These were for repositioning 12 lead migrations in 10 patients, high impedance in 2, implanted pulse generator migration in 2, discomfort because of lead anchor in 2, pulse generator failure in 1 and device explantation in 1 patient (Decker 2015).

13 patients with lead fractures had surgical revisions to implant new leads in the case series of 53 patients (Deckers 2018).

Device explantation

Device explantation was reported in 15.7% (32/204) of patients in the open-label follow up of the RCT. These were because of lack of efficacy in 8.8% (18/204) of patients, infection in 2.9% (6/204) of patients, as a safety precaution before an MRI scan in 2.9% (6/204) of patients, resolution of LBP in 1 patient and relocation to a remote area without device follow-up infrastructure in 1 patient. One patient who had the device explanted after infection was reimplanted after infection resolution (Gilligan 2021).

Device explantation was reported in 16/53 (30.2%) of patients. Device explantation was because of lack of clinical benefit in 20.8% (11/53) of patients, device migration in 1.9% (1/53) of patients and after clinical benefit in 7.5% (4/53) of patients (Mitchell 2021, Deckers 2018).

Device explantation was reported in 9.5% (4/42) of patients in the case series of 42 patients because of lack of efficacy (Thomson 2021).

Device explantation (because of infection and lead migration) was needed in 1 patient in the case series of 28 patients (Deckers 2015).

Adverse events unrelated to the procedure

Thirteen serious adverse events were reported in the open-label follow up of the RCT but were reviewed by the CEC and adjudicated as unrelated to the device or procedure (Gilligan 2021).

69 adverse events unrelated to the procedure were reported in 53% (28/53) of patients in the case series of 53 patients. 3 of these were serious events and included surgical removal of a uterine fibroid, non-cardiac chest pain and a cerebrovascular accident (Deckers 2018).

37 adverse events unrelated to the device or procedure were reported in the case series of 28 patients (Deckers 2015).