Saline Hydrodissection Does Not Markedly Alter Local Temperatures in Percutaneous Transpedicular Cryoablation

Introduction: Cryoablation can be used to palliatively and/or definitively treat bone tumors. In transpedicular cryoablation of spine tumors, hydrodissection is frequently used in attempts to protect local anatomy, like nerves. No studies have investigated the direct clinical benefits of hydrodissection in spinal tumor cryoablation. Methods: To assess for any meaningful rise in temperature around the pedicle when using hydrodissection, cryoprobes were placed through the pedicles bilaterally at six vertebral levels, and a 10-minute freeze cycle was initiated. At each level, one pedicle served as a control and the other received hydrodissection. Temperature measurements were taken every minute at the inferior pedicular cortex, medial pedicular cortex, and at midline of the spinal canal. Distance measurements between the thermometers and cryoprobe were obtained with the aid of three-dimensional reconstruction software. Results: In a time-temperature regression model, the distance from the cryoprobe demonstrated a polynomial relationship with an overtly positive effect on temperature. Time, predictably, resulted in more negative temperatures. The positive polynomial relationship was maintained when looking at the final time point in isolation. Interestingly, no statistically significant change in temperature was demonstrated with use of hydrodissection. Analysis revealed an average temperature difference of 1.89°C (95% confidence interval, −2.26 to 6.05°C) throughout a 10-minute freeze cycle and −1.40°C (95% confidence interval, −8.03°C to 5.24°C) at the final. Conclusion: These results suggest that hydrodissection with saline during transpedicular cryoablation may not result in clinically relevant increases in local temperatures. As such, the time devoted to hydrodissection may be better devoted to attaining a well-placed cryoprobe.