Prevention of Nerve Root Thermal Injury Caused by Bipolar Cauterization Near the Nerve Roots

Study Design. This was a controlled, interventional animal study. Objective. This study aimed to investigate the thermal injury of nerve root by cauterization near the nerve root and to identify the prevention or rescue procedure of nerve root injury. Summary of Background Data. In spine surgery, bipolar cauterization of epidural venous plexus near the nerve root is an essential procedure to control bleeding. Although a potential risk of neurological thermal damage exists, the underlying mechanism and prevention have not been elucidated. Methods. Temperature measurement and histological evaluation after bipolar cauterization near the posterior branch of the nerve root were performed using a rabbit model. Subsequently, the effect of saline irrigation or changing the direction of bipolar forceps to reduce thermal elevation during bipolar cauterization was evaluated. Finally, the effectiveness of locally injected corticosteroid after bipolar cauterization was evaluated. Results. After bipolar cauterization, temperature of the surrounding site reached 60.9 °C, and 47.8% of the nerves were histologically injured. Using saline irrigation, thermal elevation was significantly suppressed up to 42.7 °C ( P < 0.01), and no nerve was histologically injured. When bipolar cauterization was performed in the perpendicular direction, temperature of the surrounding site reached only 40.4 °C ( P < 0.01). Locally injected corticosteroid reduced the incidence of nerve injury to 25.0%. However, a significant increase in nerve damage remained compared with the sham group ( P < 0.01). Conclusion. Bipolar cauterization near the nerve roots can increase the temperature of nerve roots and cause thermal nerve root injury, despite no accidental direct nerve root injury. Using saline irrigation, or setting bipolar forceps perpendicular to nerve roots, thermal elevation could be suppressed and nerve injury could be prevented. Therefore, it is recommended that surgeons set bipolar forceps perpendicular to nerve roots or use saline irrigation for the prevention of nerve root injury. Level of Evidence: N/A