Methods and systems for spinal radio frequency neurotomy

What is this patent about?

'688 is related to the field of thermal ablation, specifically radio frequency (RF) neurotomy. This technique involves using heat generated by RF energy to create necrosis in a targeted tissue volume, such as a nerve, to disrupt its function. A key challenge in thermal ablation is to precisely target the tissue while minimizing damage to surrounding structures. Spinal RF neurotomy, in particular, aims to cauterize nerves to block pain signals, but access limitations and anatomical variations make it difficult to create effective lesions with conventional RF probes.

The underlying idea behind '688 is to enhance the effectiveness and precision of RF neurotomy by using a needle with deployable filaments at its tip. These filaments, when extended, increase the active surface area from which RF energy emanates, creating a larger and more customizable lesion. The filaments can be retracted for insertion and precise placement of the needle tip, then deployed to expand the RF field, allowing for targeted ablation of nerves even in areas with limited access or anatomical variability. This approach overcomes the limitations of conventional single-electrode RF probes, which often struggle to create lesions of sufficient size and shape.

The claims of '688 focus on a system comprising an RF probe and a needle. The needle includes a hub, an elongate member with a lumen, a tissue-piercing tip, a plurality of filaments, and an actuator. The actuator controls the deployment and retraction of the filaments relative to the tip. A fitting, such as a Luer fitting, allows for fluid injection and insertion of the RF probe into the lumen. The key aspect is that the lumen is configured to allow the RF probe to physically contact a conductive portion of the needle, electrically connecting the probe to the tip and filaments. This arrangement enables the RF probe, tip, and filaments to function together as a monopolar RF electrode, with the filaments movable between retracted and deployed positions when the RF probe is not inserted.

In practice, the physician inserts the needle with the filaments retracted to a position near the target nerve, guided by imaging techniques like fluoroscopy. Once the tip is correctly positioned, the actuator is used to deploy the filaments, expanding the active RF energy delivery area. The RF probe is then inserted through the fitting and into the lumen, making electrical contact with the needle's conductive components. When RF energy is applied, it emanates from both the tip and the deployed filaments, creating a larger, more targeted lesion that ablates the nerve. The fluid injection capability allows for the delivery of anesthetics or contrast agents to further enhance the procedure.

This design differentiates itself from prior approaches by providing a means to customize the lesion size and shape without needing to reposition the needle multiple times. The deployable filaments allow for a larger ablation volume compared to standard RF probes, while the ability to retract them facilitates precise needle placement. The monopolar configuration simplifies the system, and the fluid injection capability adds another layer of utility. By increasing the active surface area for RF energy delivery, the invention enables more effective and targeted nerve ablation, potentially leading to improved pain relief for patients.