Cryoneurolysis Thermal Graphs: In Vivo Descriptive Data from Ultrasound-guided Percutaneous Thermocouples.

Area of Science:

• Pain management
• Minimally invasive procedures
• Peripheral nerve interventions

Background:

• Cryoneurolysis uses extreme cold to reversibly ablate peripheral nerves for analgesia.
• Maintaining a precise therapeutic temperature window (-20°C to -100°C) is critical to avoid nerve damage or inadequate treatment.
• Deviations outside this window can lead to persistent pain or permanent nerve injury.

Purpose of the Study:

• To investigate the relationship between returning gas temperature and adjacent tissue temperature during ultrasound-guided cryoneurolysis.
• To evaluate the effectiveness of cryoneurolysis in reaching target therapeutic temperatures in intercostal nerves.
• To identify factors influencing temperature achievement, such as treatment duration and concurrent nerve blocks.

Main Methods:

• Ultrasound-guided cryoneurolysis was performed on intercostal nerves in patients undergoing mastectomy or treated for rib fractures.
• A percutaneous thermocouple measured tissue temperature adjacent to the cryoprobe.
• Returning argon gas and tissue temperatures were correlated, with data presented due to small sample size.

Main Results:

• In 71% of treatments, tissue adjacent to the probe did not reach -20°C after 3 minutes, and in 42% after 5 minutes.
• Adjacent tissue temperatures were significantly warmer than the returning gas, especially with a concurrent nerve block.
• Consecutive treatments on adjacent nerves showed decreasing tissue temperatures, indicating a cumulative cooling effect.

Conclusions:

• Tissue temperature during cryoneurolysis is often deceptively warmer than the returning gas.
• Extending treatment duration to 5 minutes improves the likelihood of reaching therapeutic temperatures.
• Concurrent peripheral nerve blocks may hinder achieving target temperatures, and caution is advised for sequential nerve treatments.