Failure Modes

by James Cavuoto, editor

The field of neuromodulation has seen a number of therapeutic and commercial success stories in the 25 years that we have been publishing this newsletter. When a new therapy or commercial device experiences a successful outcome, there is no shortage of coverage in the general press, in scientific journals, and at clinical society meetings.

But when a device or therapy experiences failure, there is often very little coverage of what went wrong. This is unfortunate, since it deprives other investigators and entrepreneurs of the opportunity to learn from the shortcomings of the experience or to modify their models of mechanisms of action. In this publication, we have tried to report on the bad news, as well as the good news surrounding clinical trials and commercial ventures. But the neuromodulation community should take it upon itself to be more forthcoming with negative data.

This was the subject of a thought-provoking talk given by Lawrence Poree, a professor and pain doctor from UC San Francisco, at the recent PARC Neuromodulation Symposium, produced by the Pain and Addiction Research Center at UCSF.

Looking at pain neuromodulation therapies in particular, Poree honed in on the loss of efficacy and rate of explants with current SCS devices. Citing several studies, he pointed out that the main reason for device explants—ranging from 44 to 73%—was loss of efficacy and inadequate pain relief. With cardiac pacemakers, by contrast, more than 90% of explants are due to battery depletion and not loss of efficacy.

Poree compared the therapy survival rate for SCS to that of VNS and DBS implants, and noted the average useful lifetime of an SCS implant was significantly shorter than for VNS or DBS devices. While the FDA mandates reporting of death or serious injury resulting from implanted devices, medical facilities are only encouraged to report malfunctions that do not rise to that level.

A survey sponsored by the North American Neuromodulation Society reported that 64% of implanters did not even know where to report device failures or if there was a procedure for doing so. “This is the reason for transparency,” Poree exhorted. “If we hide it, we don’t find the problem. If we don’t find the problem, we don’t find the solution.”

For these reasons, we were pleased to learn of a new publication in the journal Acta Biomaterialia that examined the physical degradation of intracortical microelectrodes that had been implanted in NeuroPort users’ brains for a significant length of time. The data that the team reported will likely be beneficial to other teams developing new brain implants.

One of the authors of this report on the mechanisms of electrode damage, Loren Rieth of West Virginia University, was excited to share the results with other investigators. “For myself, this has been an amazingly positive collaboration across a large team,” he wrote on LinkedIn. “This work helps take a step towards understanding what impacts neural electrode performance, and how these factors change over time.”

While it’s understandable that investigators, clinicians, and entrepreneurs might be hesitant to report on their own failures, the ultimate success of their field may hinge on their willingness to do so.