Patients are suing medical device makers for selling spinal cord stimulators to treat chronic back pain but allegedly triggered worsening pain and electric shocks. The complaints, however, will face a tall legal hurdle in court called preemption.

Several patients with Medtronic spinal cord stimulators allege the company skirted regulatory approvals while updating devices approved under an application dating to the early 1980s. The lawyer behind the complaints said he has "hundreds" of similar clients, including one who has sued Boston Scientific under similar accusations.

The complaints against Medtronic, filed in U.S. District Court in Minnesota, also allege the U.S. Food and Drug Administration approved the changes through "expedited channels" without requiring Medtronic or Boston Scientific to submit new clinical safety data. Both companies employ thousands in Minnesota.

The lawsuits, which share similar language and say the companies' actions violate state laws, allege, "these changes materially altered the safety and functionality profile of the system but were not disclosed to physicians or patients." The lawsuits name the FDA as a defendant, as well as the manufacturers.

The companies say the complaints lack legal merit, and industry lawyers add that the cases can't succeed because of the doctrine of preemption, which blocks injury lawsuits against well-studied medical devices.

The three cases against Medtronic involve plaintiffs Angela Yates and Dilly Anderson of Kentucky and Cathryn Keys of Tennessee, who received spinal cord stimulators treating chronic back pain between 2015 and 2020. Anderson and Keys still have the implant, while Yates had her spinal cord stimulation system explanted in 2023.

A Medtronic spokesperson said the company has not been served in any of the cases.

"However, we are aware of allegations from Ms. Yates and while we have deep sympathy for her, we believe this case lacks merit, including because claims such as this are preempted under federal law," the spokesperson said. "Patient safety is a top priority at Medtronic, and we stand by the quality of our device."

Director of Litigation Robert Caldwell of the Wilhite Law Firm represents the three plaintiffs and said in an email his firm has hundreds of spinal cord stimulator clients. Other attorneys have filed suits too, he said, "who also have at the very least hundreds of clients."

The Medtronic complaints follow a similar case Caldwell recently filed in California against Boston Scientific. Patient Dena Lawler of Kentucky alleged Boston Scientific changed its original devices in ways that "materially altered the device's safety and effectiveness profile compared to the originally approved Precision system, triggering regulatory obligations that Boston Scientific failed to fulfill."

A Boston Scientific spokesperson said in an email that the company doesn't "believe the case has merit and intend[s] to vigorously defend these claims."

"Patient safety is of the utmost importance, and we dedicate significant resources to deliver safe, high-quality products," the spokesperson said.

Spinal cord stimulators are implanted devices that send low levels of electricity into the spinal cord to relieve pain. Similar to a traditional pacemaker, they consist of a small battery pack called a generator connected to thin wires called leads, tipped with electrodes that deliver electric current.

Research published in the Cochrane Database of Systemic Reviews analyzing more than a dozen studies suggests spinal cord stimulation "probably does not have sustained clinical benefits that would outweigh the costs and risks of this surgical intervention."

In a 2008 case, Riegel v. Medtronic, the Supreme Court gave medical device companies broad immunity from product liability under state law if the FDA had approved a device for any use through a rigorous process called a premarket approval, or PMA.

James Beck, a senior life sciences policy analyst with law firm Reed Smith, which has represented large medtech companies, said plaintiffs' claims alleging that design changes violate a state law often fail.

"As long as you make the design that the FDA approved, any claim that [a device] is unreasonably dangerous under state law is an attack on the FDA's approval of the design," Beck said.

Plaintiffs also cannot sue the FDA for approving a device because the agency's regulatory function is discretionary, he argued. The Federal Tort Claims Act, allowing plaintiffs to sue the government, exempts the United States from liability for employees failing to perform a discretionary duty, lawyers say.

Beck said spinal cord stimulators "don't always work. And that's OK, because the FDA understands that all devices have risks, which is why you have doctors giving prescriptions for them, and you don't let people buy them in a hardware store."

A spokesperson for the U.S. Department of Health and Human Services, which oversees the FDA, said the department does not comment on ongoing litigation.

Caldwell said he's bound by attorney rules to "not litigate cases outside the courtroom, but we look forward to a federal district court's ruling and the executive branch's attention here in resolving fraud, waste and abuse in FDA, as the current administration has claimed to seek."

The complaints allege:

The company was the first to obtain FDA approval for a fully implantable spinal cord stimulator for its Itrel II system in 1984. Since then, the company has made changes to the generator and leads through more than 400 PMA supplements filed with the agency.

"These modifications collectively transformed the Medtronic SCS system into a materially different device from the Itrel II platform originally approved in 1984," the Anderson and Keys complaints said.

Keys and Anderson were implanted with Intellis systems approved under the original Itrel application and "supplemented through a series of streamlined FDA processes that did not require new clinical testing, including 30-day notices and real-time review pathways."

Yates' device was also approved under the original application. After her implantation in 2015, she felt "burning sensations, erratic electrical shocks, and exacerbation of her preexisting pain. The stimulation was unpredictable, sometimes triggering without cause or intensifying suddenly during normal activities." Anderson and Keys experienced similar problems.

For years before device removal in 2023, Medtronic personnel "failed to provide useful assistance" to Yates and were "dismissive of Plaintiff's reported complications and provided no meaningful clinical or safety guidance."

Anderson and Keys, still implanted with the devices, continue "to experience persistent pain, diminished quality of life, and a lack of therapeutic benefit from the Intellis system."

"At no time did Medtronic disclose that the modifications approved through PMA supplements had not been validated through clinical trials or subjected to renewed FDA safety review," the patients' lawsuits say.

Lawler received a Boston Scientific stimulator in October 2022, and within a month, "began experiencing new and worsening symptoms, including burning pain at the implant site, ineffective pain relief, and abnormal sensations inconsistent with the therapeutic goals of the device."

The device had to be reimplanted about three months after the initial procedure after evaluations revealed the devices' leads had moved. Lawler developed persistent chest pain and a cardiac of arrhythmia diagnosis in early 2021.

The patients said their symptoms are consistent with reports filed in the Manufacturer and User Facility Device Experience Database tracking medical device adverse events.

Medtronic and Boston Scientific failed to comply with obligations to file reports with the FDA for each new reportable event and revise its product labeling to reflect evolving safety information, the lawsuits said.

The complaints called the FDA's approval of the Medtronic and Boston Scientific systems "arbitrary and capricious."

"By approving the [Medtronic] Intellis system and its subsequent modifications through successive PMA supplements, the FDA departed from its statutory and regulatory obligations," the Keys and Anderson complaints say.