Implanted Peripheral Nerve Stimulation Systems: What Patients Should Know About Complications, MAUDE Reports, and Active Litigation

June 02, 202611 minute read

Published by Justpoint Inc.

If you have — or are about to have — an implanted peripheral nerve stimulator (PNS), recent regulatory data and an active wave of U.S. neurostimulator litigation make this a moment to pay attention. A peer-reviewed analysis of the FDA’s MAUDE database identified 594 unique medical device reports for FDA-approved implantable PNS systems used for pain in a single year (2023), describing over a thousand distinct adverse events. The same data set found that device-related adverse events made up approximately 40.1% of distinct events, with procedural complications adding 32.7% (Cooper et al. 2025), and that between 43.8% and 46.3% of reported events led to device explantation — that is, the device had to be surgically removed.

At the same time, the U.S. legal landscape around implanted neurostimulators is changing fast. An individual product-liability suit was filed against Boston Scientific in May 2025 alleging neurostimulator-related harm, and on February 20, 2026 a motion was filed with the Judicial Panel on Multidistrict Litigation (JPML) to centralize a separate but related stream of spinal-cord-stimulator cases against Boston Scientific and Abbott into a federal MDL (proposed as MDL No. 3181). A JPML hearing on that motion is scheduled for May 28, 2026 in Milwaukee. The PNS category sits next to that litigation — same general clinical area (implanted neurostimulation for chronic pain), overlapping manufacturers, and largely overlapping symptom patterns (lead migration, shocks, infection, revision surgery).

This article explains what implanted PNS systems are, what the published evidence shows about their complication profile, how to figure out which specific device you have, which symptoms warrant immediate attention, and what your reporting and verification options look like.

What an implanted peripheral nerve stimulator is

A peripheral nerve stimulator is a small implantable electrical device that delivers low-voltage pulses to a specific peripheral nerve — typically a nerve in the arm, leg, shoulder, lower back, or head/face — to interrupt the chronic pain signal that the nerve is carrying to the brain. It is not the same as:

A spinal cord stimulator (SCS), which places electrodes in the epidural space along the spinal cord rather than on a single peripheral nerve.
A deep brain stimulator (DBS), which targets brain structures (most commonly for Parkinson disease or essential tremor).
A sacral neuromodulation device, which targets sacral nerves for bladder or bowel control.

Implantable PNS systems are typically used for chronic intractable peripheral neuropathic pain — pain that has not responded to medications, injections, physical therapy, or surgery — and most often for conditions such as post-amputation (stump or phantom-limb) pain, post-surgical neuropathic pain, occipital neuralgia (back-of-head nerve pain), and certain post-traumatic mononeuropathies.

The FDA classifies most implanted PNS systems as Class II medical devices under the product code GZF — “Stimulator, peripheral nerve, implanted (pain relief)” — regulated under 21 CFR 882.5870. A second related code, NHI, is used for some newer percutaneous-lead PNS systems. Class II means the FDA reviews the device under the 510(k) “substantial-equivalence” pathway rather than the full premarket approval (PMA) trial process that Class III devices require.

Which devices and manufacturers fall in this category

The FDA-cleared implantable PNS field includes (this is a representative list, not an exhaustive one):

StimRouter® Neuromodulation System — originally cleared for Bioness, Inc. (K142432, K181422, K190047, K200482). Bioness was acquired by Bioventus Inc. on March 30, 2021, so the StimRouter is now manufactured and sold by Bioventus (NYSE: BVS), Durham, North Carolina.
SPRINT® PNS System — SPR Therapeutics, Inc. (Cleveland, Ohio); a 60-day percutaneous-lead system.
Nalu™ Neurostimulation System — Nalu Medical, Carlsbad, California; Boston Scientific announced an agreement to acquire Nalu Medical in 2024, bringing Nalu into the Boston Scientific neuromodulation portfolio alongside its spinal-cord-stimulator product line.
Freedom® PNS System — Curonix LLC (formerly Stimwave Technologies). Stimwave’s earlier StimQ PNS System was subject to a 2020 Class 2 device recall.
ReActiv8® — Mainstay Medical, for chronic mechanical low-back pain.

MAUDE reports filed under product code GZF span multiple manufacturers in this category. The list above reflects the FDA-cleared implantable PNS systems currently in U.S. clinical use. Adverse-event reports cited later in this article are aggregated across the product-code category rather than attributed to any single manufacturer; readers interested in manufacturer-specific event counts can search the FDA MAUDE database directly.

What the published evidence shows

The most current peer-reviewed analysis of safety reporting for FDA-approved implantable PNS systems is Cooper et al., “Adverse Events Associated With Peripheral Nerve Stimulation: An Analysis of the MAUDE Data base and Implications for Pain and Spine Clinicians,” Neuromodulation: Technology at the Neural Interface, June 2025 (Volume 28, Issue 4, pages 619–626); PubMed: https://pubmed.ncbi.nlm.nih.gov/40178466/; DOI: https://doi.org/10.1016/j.neurom.2025.02.002.

The Cooper team queried MAUDE for medical device reports filed between January 1, 2023 and December 31, 2023 for the five FDA-approved implantable PNS systems indicated for pain and spine indications. Their key findings (all figures from Cooper et al. 2025):

594 unique medical device reports were identified.
Those 594 reports described 1,012 distinct adverse events (a single MDR often describes more than one event).
Device-related adverse events made up approximately 40.1% of distinct events, with procedural complications adding 32.7%.
Infections accounted for approximately 22.7% of all reported events and around 26.8% of procedural events.
Lead migration — the lead wire physically moving away from the target nerve — was reported in 10.5% to 14.7% of events.
Lead erosion or skin erosion over the device was reported in 8.1% to 9.4% of events.
Unexpected electric shocks — uncontrolled or unintended stimulation — were reported in approximately 4.5% of events.
Explantation (surgical removal of the device) was the eventual outcome in 43.8% to 46.3% of events.
Surgical revision (a second operation to reposition, replace, or repair the system) was required in approximately 17.7% of events.

The authors’ clinical takeaway: most adverse events for implanted PNS systems were “device- or procedure-related,” not biological or therapeutic failures, and infection, lead migration, and skin erosion were the three single most common adverse events.

It is important to keep these numbers in context: they describe the distribution of events among MAUDE reports, not the population-level incidence in all implanted patients. MAUDE is a passive surveillance system — it captures events that someone (manufacturer, clinician, patient) chooses to report. The real rate of complications in the implanted population may be higher or lower; what the analysis reliably tells you is what kinds of problems do happen and roughly how their relative frequency compares.

These figures describe reported associations from a passive-surveillance dataset without a denominator of implanted devices; association does not establish causation, and reporting bias and selection bias may shape the observed proportions.

Plain-language explanation of each problem

Lead migration. The “lead” is the thin wire that delivers the electrical pulse from the implanted stimulator to the target nerve. If the lead shifts even a few millimeters away from the nerve, the stimulation may stop working — either silently (you suddenly notice the pain returning) or with a change in the sensation. Repositioning the lead requires another procedure.

Lead erosion / skin erosion. Over time, the lead or the implantable pulse generator can wear through the overlying tissue, exposing the hardware to the outside. This may cause pain and bleeding and is associated with infection risk. The fix is usually surgical — either revision or removal.

Unexpected electric shocks. Patients describe these as sudden, sharp, unpleasant pulses that are not the usual therapeutic stimulation. Shocks can be caused by lead breakage, generator malfunction, electromagnetic interference, or component failure. They are distressing and a clinical reason to seek prompt evaluation.

Procedural complications. These are the complications that arise around the implantation surgery itself — infection at the surgical site, bleeding, problems with anesthesia, nerve injury during placement, or inadequate placement on the target nerve.

Infection. Wound infection, pocket infection (around the implanted pulse generator), or deeper infection along the lead is the single most common adverse event in the published MAUDE analysis. Persistent redness, warmth, swelling, drainage, or fever after PNS implantation should be evaluated promptly.

Who is most at risk

The MAUDE-based analyses do not single out a clear “highest risk” patient subgroup, but a few clinical patterns emerge from the broader peer-reviewed literature on PNS:

Patients whose implants have been in place for the longest time have had the most cumulative exposure to mechanical wear, lead migration, and biofilm-related infection.
Patients undergoing repeated revision are at higher risk for further complications with each additional procedure.
Patients with thin overlying soft tissue at the implant site, or with conditions that impair wound healing (diabetes, immunosuppression, prior radiation), may be more susceptible to skin erosion and infection.

If you have one of these risk profiles, the threshold for getting symptoms evaluated should be lower, not higher.

Warning signs to monitor

Based on the most commonly reported adverse events, symptoms you may want to watch for include:

Pain, redness, warmth, or swelling at the implant site (pulse-generator pocket) or along the lead path — possible signs of infection.
Drainage, weeping, or visible hardware through the skin — possible signs of erosion.
Sudden loss of stimulation or sudden return of your original pain — possible lead migration, lead breakage, or generator failure.
Unexpected shocks, muscle twitches, or stimulation in an area you don’t normally feel it — possible component malfunction or migration.
A bulge, tenderness, or change in shape over the implanted pulse generator — possible seroma, hematoma, or device displacement.
Fever, chills, or general illness in the weeks after implant or revision — concerning for deep infection.

None of these symptoms is exclusively caused by a device problem. They overlap with other surgical and medical conditions. But all of them deserve prompt evaluation rather than waiting.

How to confirm exactly which device you have

If you are not sure of the make and model of your stimulator, several pathways can help identify it:

Your operative report. Hospitals are required to retain the operative report from your implant surgery. It will name the manufacturer (e.g., Bioventus, Boston Scientific/Nalu, SPR Therapeutics), the system name (e.g., StimRouter, Nalu, SPRINT, Freedom), and a model or catalog number. You can request a copy through the hospital’s medical records department. Federal law (HIPAA) gives you the right to obtain your own records.
Your patient programmer or implant card. Most PNS systems include a patient programmer (a remote-control device that lets you adjust or pause stimulation) and/or a patient identification card. Both typically display the system name and model. The patient programmer is one of the easiest indirect identifiers because it carries the manufacturer’s branding.
Your implanting physician’s office. A short message through the patient portal — “Could you confirm the manufacturer, model, and serial number of the peripheral nerve stimulator implanted on [date]?” — is normally answered quickly because the same information is in their procedure records.
Your regular healthcare provider. If you do not know who performed your implant procedure or cannot easily contact that office, your primary care provider or another healthcare professional may be able to help you obtain the necessary records or direct you to the appropriate source for device information.

Once you have these details, write them down (manufacturer, system name, model number, lot or serial number, date of implant) and keep them with your other medical paperwork. If a recall or safety communication is later issued, you will need this information to know whether your specific device is covered.

What to do if you think your device is causing harm

Contact your implanting physician or pain specialist promptly. Describe the symptom in detail and when it started. Many PNS systems can be interrogated (electronically read) by the implanting team to check whether the device is delivering stimulation correctly, whether the lead impedance has changed, and whether the battery is functioning.
Do not stop using the device on your own without first consulting your clinician, but do note when symptoms started in case the device is later adjusted or removed.
Ask your physician to document the adverse event in your medical record. Specifically ask whether a MAUDE report number will be assigned, and ask for that number. Manufacturers and clinicians are required to report certain device-related events to the FDA; you have a right to ask whether such a report has been filed.
Keep copies of everything — the operative report, imaging, device interrogation printouts, manufacturer correspondence, and any patient programmer logs.

Reporting an adverse event to the FDA — MedWatch

You do not have to wait for your clinician to file a report. Patients and family members can submit reports directly to the FDA’s adverse-event program, MedWatch:

Online: www.fda.gov/medwatch (Form FDA 3500B is the consumer version)
Phone: 1-800-FDA-1088 (1-800-332-1088)
Mail/fax: instructions are on the FDA MedWatch web page

Patient-submitted reports do not initiate a legal claim and are not a substitute for medical care, but they add to the data the FDA uses to monitor implant safety patterns. They are also helpful documentation if you later consult an attorney.

Searching MAUDE for your specific device

Adverse-event reports that are already on file can be searched at the FDA’s MAUDE database:

MAUDE Search homepage: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/search.cfm
In the Product Code field, enter GZF (the FDA product code for implanted peripheral nerve stimulators for pain). Some newer percutaneous systems are coded NHI — you can run a separate search using that code.
In the Manufacturer Name field, you can enter “Boston Scientific,” “Bioventus,” “Bioness,” “Nalu Medical,” “SPR Therapeutics,” “Curonix,” “Stimwave,” or any of the other PNS manufacturers.
You can also restrict by date range and by event type.

Results are public. Each individual report shows the device, the manufacturer, the event narrative as submitted, and the outcome. Searching by product code rather than by trade name catches reports filed under variant model numbers and avoids missing relevant data.

Regulatory and litigation context

As of this writing, the FDA has not issued a category-wide recall for implanted peripheral nerve stimulators as a class. Individual systems have been the subject of recalls and corrections — for example, Stimwave Technologies’ StimQ PNS System was the subject of a Class 2 recall in 2020 — but no class-wide PNS safety communication has been published. The FDA continues to track and publish MAUDE reports for the product code.

On the litigation side, several related developments matter for patients:

May 1, 2025 — Boston Scientific neurostimulator suit. An individual product-liability action naming Boston Scientific was filed in May 2025 alleging neurostimulator-related harm. Public reporting from law-firm trackers identifies a Boston Scientific stimulator case filed in the U.S. District Court for the Central District of California in May 2025.
February 20, 2026 — JPML motion to centralize spinal-cord-stimulator cases. A motion was filed asking the JPML to centralize federal spinal-cord-stimulator (SCS) lawsuits against Boston Scientific and Abbott into a single multidistrict litigation, proposed as MDL No. 3181 — Abbott and Boston Scientific Spinal Cord Stimulator Products Liability Litigation. That motion concerns spinal cord stimulators, not implanted peripheral nerve stimulators specifically, but the manufacturers, complication categories (lead migration, shocks, revision), and clinical use case (implanted neuromodulation for chronic pain) overlap heavily with the PNS device space.
JPML hearing scheduled May 28, 2026 — Milwaukee. The JPML is set to hear oral argument on the proposed SCS MDL on May 28, 2026. Abbott and Boston Scientific have filed briefs opposing centralization.

The broader history of implanted-neuromodulation litigation also provides context — for example, in 2019 Medtronic reportedly established an approximately $35 million master settlement fund to resolve claims of roughly 500 patients allegedly harmed by its SynchroMed II implantable intrathecal drug pump (as reported by MassDevice and the Star Tribune; see Sources). That settlement followed earlier FDA enforcement action including a 2015 consent decree between Medtronic and the U.S. Department of Justice over uncorrected manufacturing violations affecting the SynchroMed II. The precedent does not predict any outcome for PNS or SCS litigation, but it shows that implantable neuromodulation products have previously been the subject of resolved U.S. mass-tort processes.

Because legal outcomes depend on the particular circumstances of each case, past settlements cannot guarantee future results.

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Omnipod 5 Pods Recall: Internal Tubing Tear, Insulin Leakage, and What to Do — Omnipod 5 — another automated insulin-delivery pump with a 2026 Class I recall

Sources and how to verify

Cooper AN, Sen H, Kanjanapanang N, Saad K, Wahl G, Young C, Essman M, Fogarty AE, Burnham T, Conger AM, McCormick ZL, Glinka Przybysz A. “Adverse Events Associated With Peripheral Nerve Stimulation: An Analysis of the MAUDE Data base and Implications for Pain and Spine Clinicians.” Neuromodulation: Technology at the Neural Interface. 2025 Jun;28(4):619–626. Epub 2025 Apr 3. PubMed: https://pubmed.ncbi.nlm.nih.gov/40178466/. DOI: https://doi.org/10.1016/j.neurom.2025.02.002. The published source for the 594-MDR, 1,012-distinct-event analysis covering January 1 – December 31, 2023 MAUDE reports for FDA-approved implantable PNS systems.
FDA MAUDE Database. Search at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/search.cfm. Product codes for implanted PNS: GZF (regulation 21 CFR 882.5870, “Stimulator, peripheral nerve, implanted”) and NHI (related percutaneous-lead PNS).
FDA Product Classification – GZF. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPCD/classification.cfm?ID=GZF.
FDA MedWatch (patient adverse-event reporting). www.fda.gov/medwatch or 1-800-FDA-1088.
Bioventus acquisition of Bioness, Inc., March 30, 2021. Bioventus Inc. press release / SEC disclosure (NYSE: BVS).
Boston Scientific acquisition of Nalu Medical — Boston Scientific corporate news release describing the agreement to acquire Nalu Medical and its peripheral-nerve-stimulation platform.
JPML Pending MDLs list. https://www.jpml.uscourts.gov/pending-mdls — search “spinal cord stimulator” for the status of the proposed MDL No. 3181 (Abbott and Boston Scientific Spinal Cord Stimulator Products Liability Litigation) and the May 28, 2026 hearing.
Medtronic SynchroMed II implantable intrathecal drug pump — approximately $35 million settlement fund (2019). Public reporting: “Report: Medtronic establishes $35m settlement fund for Synchromed pumps,” MassDevice, June 2019 (https://www.massdevice.com/report-medtronic-establishes-35m-settlement-fund-for-synchromed-pumps/); “Medtronic to create $35M settlement fund for implantable drug pump lawsuits,” Star Tribune, June 2019 (https://www.startribune.com/medtronic-to-create-35m-settlement-fund-for-implantable-drug-pump-lawsuits/561565622). Background context only; the SynchroMed II is a separate device from the PNS systems addressed in this article.
U.S. statute-of-limitations references for product-liability claims vary by state and depend on the date of injury and the date of discovery of the connection between the device and the harm. A qualified attorney in your state can confirm the deadline that applies to your case.

This article was published by Justpoint Inc. The information provided is for educational purposes, does not constitute medical or legal advice and is based on publicly available research and regulatory communications. Findings may vary depending on individual circumstances, device type, and clinical context. If you have a medical device that may be affected, please consult your physician. If you believe you may have a legal claim, please consult a qualified attorney.

Justpoint Inc. supports Justpoint Law (Justpoint PLLC) by providing operational and administrative services. All legal services are provided by Justpoint Law, and any client-related communications are made on its behalf.

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