May 2026 issue, BioElectRx Business Report
May 31, 2026 | While FDA 510(k) regulatory codes are established for specific purposes, they frequently evolve by gaining new clinical objectives over time. A clear illustration of this regulatory evolution can be seen in the ETN code, which has been associated with 143 FDA-cleared devices for intraoperative nerve monitoring since 1978.
Originally, this code was applied to intraoperative monitoring of peripheral, spinal, and cranial nerves, requiring brief electrical stimulation to be directed to these nerves while monitoring the resulting evoked EMG responses across several muscles. By utilizing such physiological feedback, surgeons can accurately identify nerves and confirm their preservation to minimize the risk of accidental damage—a safeguard that is particularly vital during highly invasive spinal, intracranial, and ENT surgeries.
Over the years, the scope of the ETN code expanded well beyond basic hook and probe-tip stimulation electrodes or standard surface and needle EMG electrodes. Surface EMG monitoring technology itself experienced relatively minor changes from its original adhesive disk design, with the only notable innovation being the soft hydrogel electrodes introduced by Neurovision Medical Products (2011). In sharp contrast, electrodes used for laryngeal EMG monitoring in ENT surgeries underwent significant development. While initial laryngeal electrodes were embedded directly within the endotracheal tube, developers later created thin, flexible alternatives designed to be wrapped around the tube using a variety of substrate materials. These materials included polyvinyl developed by Spes Medica (2009) and Medtronic Xomed (2025), polyethylene by Technomed Europe (2012), and polyester options by Magstim (2007), Inomed Medizintechnik (2009), and Suzhou Haishen Medical Device Associates Co. (2023).
Nerve stimulation electrodes also experienced an extensive evolution from their original formats as simple hooks or ball-shaped probe tips. This structural progress brought about polyurethane semi-cuff designs from Checkpoint Surgical (2021), silicone cuffs from Nvision Biomedical Technologies (2023), and silicone cuffs featuring embedded nitinol springs from Retropsoas Technologies (2024). Most recently, Epineuron Technologies developed a linear probe in 2025 equipped with two bipolar contacts that closely resemble deep brain stimulation leads. While Epineuron’s current FDA clearance is strictly for INM, the company is actively investigating a therapeutic application to promote axonal regeneration and nerve regrowth in cases of nerve damage.
In tandem with these changing electrode shapes and materials, devices cleared under the ETN code have broad implications for the overall usability of the INM procedure itself. Because INM is routinely executed during tissue dissection, surgeons frequently face difficulties when trying to co-insert a standalone stimulation electrode alongside an array of standard surgical instruments, such as scissors, forceps, rongeurs, drills, burr guards, dilators, hemostats, retractors, and screwdrivers. To streamline this workflow, it became logical to combine nerve-stimulating capabilities directly with surgical tools by electrically insulating the instruments and utilizing their functional tips as stimulation electrodes. Such dual-purpose surgical instruments were developed by Medtronic Xomed (2001), Baxano (2008), Axon Systems (2009), NuVasive (2011), Technomed Europe (2011), and Neurovision Medical Products (2012). Furthermore, because INM is critical during tumor resections where suction probes are needed to aspirate fluids and tumor tissue, specialized stimulating electrodes featuring built-in suction probes were manufactured by Neurovision Medical Products (2011) and Inomed Medizintechnik (2021).
The next phase in the usability of INM electrodes advanced even further by completely eliminating the need for independent EMG electrodes. Instead, the nerve stimulation electrode was redesigned to handle a secondary task: simultaneous recording of evoked action potentials right within the nerve. These innovative closed-loop stimulation electrodes were engineered by Xian Friendship Medical Electronics Co. (2011) and Ad-Tech Medical (2015).
Ultimately, the technological journey of INM electrodes governed by the ETN code highlights not only the highly innovative nature of the neuromodulation device industry, but also the accommodating flexibility of the FDA’s 510(k) clearance framework. This regulatory environment permits feature creep and indication expansion to unfold naturally as the clinical utilization of INM electrodes continually adapts to the expanding variety and complexity of modern surgical procedures.
