Application of continuous intraoperative neuromonitoring in the study of spinal nerve root thermal injury in a porcine model

BackgroundA warning system to avoid potential nerve root thermal injury caused by automatic spine robot is essential. However, there is a lack of basic research to support the development of such warning system. The aims of this study are to confirm the feasibility of continuous intraoperative neuromonitoring (CIONM) in spinal nerve root monitoring and study the exposure time of spinal nerve root thermal injury at different temperature in a porcine model.MethodsThe experiment was carried out on 32 nerve roots of 4 pigs (bilateral L4-S1 nerve roots). Sham group (CIONM only), control group (Room temperature stimulation with CIONM), and 40 degrees C, 45 degrees C, 50 degrees C, 55 degrees C, 60 degrees C, 65 degrees C temperature stimulation groups were conducted at random in each pig. The change of EMG was recorded continuously. The exposure time of nerve root injury at different temperatures was recorded. Histological analysis of the nerve roots was performed to confirm the injury.ResultsThe EMG of the sham, control, 40 degrees C and 45 degrees C groups were stable during the experiment, and no significant nerve root injury was observed on histological analysis. The time of 50% EMG amplitude decrease in 50 degrees C, 55 degrees C, 60 degrees C and 65 degrees C groups were 277.5 +/- 18.2, 59.5 +/- 6.2, 20.8 +/- 1.0 and 16.5 +/- 1.3 s, respectively. And the nerve specimens of these groups showed varying degrees of damage.ConclusionsCIONM can be used for continuous monitoring of spinal nerve roots. For 5 min, 40 degrees C and 45 degrees C did not cause significant nerve root injury. However, when the temperature reached 50 degrees C and above, nerve roots appeared injury.