Effect Of Cervical Rotary Manipulation On Biomechanics And Plaque Vulnerability Of Internal Carotid Artery With Severe Atherosclerosis

Background:Cervical rotary manipulation(CRM)is one of the most common spinal manipulation in clinical medicine.CRM is often applied to cervical spondylosis,torticollis and muscle strain for its obvious curative effects.However,In domestic and foreign clinical research,it found that there were some cases in clinical medicine that patients occurred dizziness,stroke and even death after received CRM.Therefore,the safety problem of CRM still remains a controversy.What were the mechanisms of those side effects?Are these risks predictable?No former research had drawn a conclusion about the questions.Objective:The purpose of this research is to explore the effect of CRM on biomechanics and plaque vulnerability of internal carotid artery(ICA)with severe atherosclerosis,and provide experimental evidence for the safety use of CRM.Method:The rabbits were selected as the object in the present study.The model of atherosclerosis was made by the method of ICA endothelial balloon injury combined with high fat feed feeding in rabbits.The studies were carried out as follow:(1)The effects of cervical rotating angle(CRA)on hemodynamics of the ICA with severe atherosclerosis;(2)The effects of CRM on hemodynamics of ICA with severe atherosclerosis;(3)The effects of CRM on tensile mechanical properties of ICA with severe atherosclerosis;(4)The effects of CRM on stability of atherosclerotic plaque in ICA.In the study of(1),left ICAs of model rabbits were chose as experimental group 1,right ICAs of model rabbits as experiment group 2,and left ICAs of normal rabbits as blank group.In the studies of(2)-(4),rabbits were randomly divided into experimental group,modeling control group,CRM control group and blank group.Rabbits in experimental group were underwent internal carotid atherosclerosis(ICAS)modeling and received CRM intervention.Rabbits in modeling control group were underwent ICAS modeling but not received CRM intervention.Rabbits in CRM control group were received CRM intervention but not underwent ICAS modeling.Rabbits in blank group were not given both interventions.Result:(1)In experiment group 2,the blood flow volume of ICA decreased when the CRA were increased(P<0.05).While in a same rotating angle,experimental group 1 have a lower peak flow velocity at the end of diastole(EDV)than the blank group,but with higher resistance index(RI)and pulsatility index(PI),except for 45°.(2)The hemodynamics of ICA(especially EDV,PI and Rl)had been influenced by atherosclerosis,but had not be influenced by CRM.ICAS has negative effects on hemodynamics of ICA.(3)Both CRM and Modeling were the main effects affecting physiological elastic modulus(PEM)of ICA.PEM in experimental group was 1.81 times as much as modeling control group,while the value in experimental group was 1.34 times as much as CRM control group.Maximum elastic modulus in experimental group was 1.80 times as much as CRM control group.Max strain in experimental group and modeling control group were 30.98%and 28.71%lower than CRM control group and blank group,respectively.However,whether treated with CRM or not,the uniaxial tensile properties of healthy ICAs were not statistically different.(4)The experimental group had increased level of hs-CRP(P<0.05),in comparison with the modeling control group,whereas effects were not significant between the CRM control group and blank group.In comparison with the modeling control group,the positive expression of CD34 and CD68 increased significantly in the experimental group(P<0.05).Conclusion:(1)Hyperlipidemia,ICAS and CRA all have negative effects on ICA hemodynamics;(2)CRM could decrease the tensile mechanical properties of rabbit ICAS,but had no significant effect on the tensile mechanical properties of normal ICA;(3)CRM could decrease the stability of ICAS plaque and increase the vulnerability of plaque.These conclusions suggest that it is important to eliminate atherosclerosis in cervical vessels before CRM intervention.The patients with atherosclerosis,especially severe atherosclerosis,should be treated with CRM carefully in order to avoid the occurrence of cardiovascular and cerebrovascular adverse events.