Authors: Ilfeld BM et al.
Anesthesiology, March 23, 2026, 10.1097/ALN.0000000000006059
Summary
This small in vivo descriptive study examined a key practical issue in cryoneurolysis: whether tissue surrounding a cryoprobe actually reaches the therapeutic temperature range required for effective and reversible nerve ablation. While the cryoprobe’s returning argon gas reaches extremely low temperatures (often below -80°C), the critical question is what temperature the adjacent nerve tissue actually experiences.
Using ultrasound-guided placement of percutaneous thermocouples approximately 3 mm from the cryoprobe, the investigators measured real-time tissue temperatures during intercostal cryoneurolysis in six patients (31 nerves total). Some patients received concurrent high-thoracic paravertebral blocks, allowing comparison of tissue cooling with and without regional anesthesia.
The results highlight a major disconnect between gas temperature and tissue temperature. Despite consistently very low gas temperatures, adjacent tissue frequently failed to reach the minimum therapeutic threshold of -20°C. After 3 minutes of treatment, 71% of nerves did not reach -20°C, and even after 5 minutes, 42% still failed to reach that threshold. This suggests that standard treatment durations may often be insufficient.
Additionally, tissue temperatures were dramatically warmer than the gas temperatures—by about 60°C without a nerve block and 95°C with a concurrent nerve block. The presence of a regional block appears to reduce the ability of tissue to cool adequately, possibly due to altered local blood flow or tissue characteristics.
Another important observation was that when multiple adjacent intercostal nerves were treated sequentially, tissue temperatures progressively decreased, even though gas temperatures remained constant. This suggests cumulative cooling effects across levels, which could increase the risk of unintended deeper or more prolonged nerve injury.
Overall, this study raises concern that clinicians may be overestimating the effectiveness of cryoneurolysis based on machine-reported gas temperatures, while actual tissue temperatures may be insufficient—or, in sequential treatments, potentially excessive.
Key Points
- Tissue temperature during cryoneurolysis is often much warmer than the cryoprobe gas temperature.
- A large proportion of treatments fail to reach the therapeutic threshold of -20°C, even after 5 minutes.
- Concurrent regional anesthesia (paravertebral block) may reduce effective tissue cooling.
- Sequential nerve treatments can lead to cumulative cooling, increasing risk of deeper tissue injury.
- Standard treatment durations may need to be longer or adjusted based on clinical context.
What You Should Know
This is a clinically important reality check. Many of us assume that if the probe is cold enough, the nerve is being adequately treated—but this study shows that is often not the case. It suggests we may be under-treating some nerves (leading to suboptimal analgesia) while potentially over-treating others when doing multiple levels. Practically, this supports longer application times, caution with multi-level treatments, and awareness that adding a block may paradoxically reduce cryoneurolysis effectiveness. This is the kind of data that should influence technique refinement more than device settings alone.
Thank you to Anesthesiology for allowing us to summarize this article.