| Objective:Spinal surgery is an effective method to treat various spinal diseases.Insufficient blood supply to the spinal cord is also a risk factor for spinal cord injury due to the frequent operation of knocking(contusion),pulling(distraction)or pushing(dislocation)to the spine.Intraoperative neuroelectrophysiological monitoring can detect nerve function damage during the operation and monitor the integrity of spinal cord nerve function.However,it is not clear to identify the cause and location of spinal cord injury.The aim of this study was to use a combination of somatosensory and motor evoked potential patterns and histological assessment to identify the cause and location of intraoperative spinal cord injury.Methods:In this study,a novel spinal cord injury device and a customized vertebra clamp were designed to establish animal models of contusion,dislocation and distraction of spinal cord injury,which were verified by histology and electrophysiology.In addition,spinal cord injury models of dislocation,distraction,and contusion were established in cervical,thoracic,and lumbar segments to evaluate the value of evoked potential patterns in identifying the location of spinal cord injury.Finally,the characteristics of somatosensory and motor evoked potentials in different patterns of spinal cord injury were studied,and the neuropathological mechanism was explored by histological analysis,so as to further evaluate the value of evoked potential pattern changes in identifying the causes of spinal cord injury.Results:1.Contusion leaded to obvious damage and hemorrhage of the spinal cord tissue.After spinal cord distraction,no obvious structural damage was observed,but scattered hemorrhage was detected,concentrated on the edge of gray matter and involving part of white matter.Spinal cord dislocation resulted in significant tissue destruction,slight atrophy,and patchy hemorrhage in gray matter and ventral white matter.Additionally,the amplitude of somatosensory and motor evoked potentials decreased and the latency was prolonged in three types of mechanical spinal cord injuries.2.After spinal cord contusion at different levels,there were obvious fissure injuries accompanied by cavity formation and hemorrhage.Fast blue staining showed that thoracic spinal cord contusion had more serious damage to corticospinal tract and gray matter tissue.Cervical contusion was more serious in gray matter than lumbar spinal cord contusion.The evoked potential results showed that somatosensory and motor evoked potentials of upper and lower limbs disappeared after cervical spinal cord contusion;After thoracic contusion,the amplitude of somatosensory evoked potential in lower limbs decreased and the latency of motor evoked potential prolonged and amplitude decreased;Lumbar contusion showed significant changes in the latency and amplitude of motor evoked potentials in lower limbs.After cervical distraction,motor evoked potentials of upper and lower limbs were attenuated.Thoracic distraction showed that the latency of the lower limbs somatosensory evoked potential was significantly prolonged and the lower limbs motor evoked potential disappeared.Lumbar distraction was characterized by the maximum latency distribution of motor evoked potentials in the lower limbs.However,histological staining only showed punctate hemorrhage without significant tissue destruction.Cervical dislocation injury was characterized by attenuation of upper limb motor evoked potential and loss of lower limb motor evoked potential;The amplitude of lower limb somatosensory evoked potentials was obviously attenuated with the disappearance of motor evoked potentials after thoracic dislocation;In addition,lumbar spine dislocation caused the prolonged latency of the somatosensory evoked potentials in lower limbs,as well as the amplitude reduction and prolonged latency of the motor evoked potentials.Hematoxylin eosin staining showed that spinal cord injury at different levels resulted in atrophy,rupture and loss of spinal tissue.Fast blue staining showed that thoracic dislocation resulted in the most severe loss of corticospinal tract and white matter,while lumbar and cervical dislocation resulted in the most significant loss in gray matter.3.Spinal cord injury demonstrated distinct differences in somatosensory evoked potential,motor evoked potential,and primary morphological changes.Contusion caused the greatest rostrocaudal extent of tissue injury and was associated with significantly attenuated somatosensory evoked potential and motor evoked potential responses.Dislocation resulted in the greatest overall loss of white matter tissue,particularly in the lateral white matter,and a greater reduction in motor evoked potential responses than contusion.Although enlarged extracellular spaces were observed without substantial structural alteration following distraction injury,somatosensory evoked potential responses slightly decreased and motor evoked potential responses were lost.Furthermore,histological and electrophysiological findings were correlated.Conclusion:In this study,a new spinal cord injury device and a customized clamp were designed to establish different mechanical spinal cord injury animal models,which was consistent with the clinical mechanism of spinal cord injury process.The same pattern of spinal cord injuries showed different pathological changes in different segments,and the parameter distribution of the evoked potential pattern also changed correspondingly,further indicating that comprehensive analysis of the change pattern of somatosensory and motor evoked potential has potential value in identifying the location of spinal cord injury.In addition,these three injury types of spinal cord injuries exhibited distinct somatosensory evoked potential and motor evoked potential changes that significantly correlate with different histologic findings,which further revealed that electrophysiologic analysis can be used to identify different causes of acute spinal cord injury. |
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