| PART ⅠBackground: post-operative cognitive dysfunction is a common complication of central nervous system after surgery.POCD can present with mental abnormality,anxiety,personality change,loss of memory and so on.Previous animal experiments have confirmed that cognitive and memory impairment was observed post-operatively in aged mice or rats.In the young mice,it was also found that the nociceptive stimulation induced by surgical incision could cause the down-regulation of the NMDA receptor type 2B in the medial prefrontal cortex(m PFC),which may be related to the decrease of postoperative memory and learning ability.However,there are few studies on the effect of preoperative chronic pain on postoperative cognitive dysfunction.In the first part of this paper,we studied the chronic pain model of non elderly SD rats,and observed the changes of cognitive function in rats after anesthesia with sevoflurane.Method:Four groups of male SD rats were divided into control group(group A),chronic pain group(group B),control plus sevoflurane group(group C)and chronic pain plus sevoflurane group(group D).The ratsin group B and D was injected subcutaneously by complete Freund’s adjuvant(CFA)to model chronic painanimals,while the rats in group A and C was injected by saline.One week later,the rats in group C and D was inhaled by sevoflurane for 3h.Morris water maze was used to evaluate the spatial learning and memory before and after of modeling and anesthesia.Result:In Morris water maze I,after injection of saline or CFA,the results of chronic pain rats were significantly lower than those of control rats,and the scores of the sevoflurane anaesthesiaed rats were significantly lower than those of the other three groups.There was no significant difference between the groups at any time in Morris water maze II.Conclusion:Chronic pain has impaired spatial memory in rats.Anesthesia alone did not lead to spatial memory impairment in rats,but anesthesia has amplified the impairment of spatial memory causing by the pain in ratsPART ⅡBackground: Post-operative cognitive disorders(POCD)is a new cognitive disorder in patients after anesthesia and surgery or a significant increase in the basis of the original cognitive impairment.POCD has been studied for more than half a century,but its exact pathogenesis and influencing factors are not fully understood.Chronic pain(chronic pain)is caused by injury stimulation have disappeared in a disease state and the pain still exists,is a common chief complaint.There have been some studies on the cognitive function impairment caused by chronic pain,but there are few studies on the effect of preoperative chronic pain on post-operative cognitive function in young and middle-aged patients.Methods:A total of 73 cases of 18-60 years old patients who underwent arthroscopic surgery,divided into preoperative chronic pain(observation group,OG),and no chronic painpreoperative(control group,CG).The two groups of patients were assessed with pain and neuropsychological scale(SKT scale)before and 24 hoursafter surgery,and 2 weeks,6 weeks,and 3 months postoperatively.Results:The VAS pain score 24 hours post-operative in the OG was significantly lower than CG,and there was no other significant difference between the OG and CG in the VAS score.Preoperative SKT evaluation of I,VI,VII subtest,the OG was significantly worse than the CG;24 hours after surgery,the OG was significantly worse than the CGin the VI and VII of SKT subtest;after 2 weeks,the OG was significantly worse than that of the CG in V,VIIof SKT subtest;the OG was significantly worse than the CG in I,V,VI,VII of SKT subtest 6 weeks later;the OG was significantly worse than that of the CG in V,VII of SKT subtest 3 months post-operatively.Conclusion:Chronic pain itself will lead to cognitive dysfunction(mainly attention),but not memory.Cognitive function will be improved by pain relief postoperatively,and it may obscure the incidence of POCD;Chronic pain can affect cognitive function,even if it is relieved,the cognitive function still cannot be recovered in 3 months.PART ⅢBackground:Pain is the Chief complaint of most patients,affects the patients’ life quality psychologically and physiologically.Many studies have confirmed that when a certain intensity of pain persisted,it is often accompanied by unpleasant emotions,disgust or fear,and may even damage the cognitive function ofthe patients.At present,it is believed that the stimulation of pain may affect the homeostasis of the central nervous system.Medial prefrontal cortex(m PFC)is associated with the intensity of pain,and has been considered to play an important role in cognitive function,but it also involved in the formation of emotion.The presence of preoperative pain may lead to an imbalance in the homeostasis of the m PFC region,including the formation of synaptic,transmitter release and synaptic plasticity in the m PFC region.The rostral ventral medial area(RVM)is considered to be the last station of the central downward regulation,and the peri-aqueductal gray(PAG)is the superior control of nuclear RVM,is the transfer station between the spinal cord and senior center.There is a balance between excitatory and inhibitory transmitters in the PAG area,and the out of this balance in the early stages of pain may have a profound impact on subsequent cognitive dysfunction.The disturbance of the homeostasis balance in m PFC region inthe patients who suffers from pain,is most likely due to dysfunction of PAG which caused by the pain stimulus and neurotransmitter abnormalities.It is hoped to detect the metabolic changes by the magnetic resonance spectroscopy and semi-quantify the changesin non elderly patients with chronic pain,and to provide evidence for functional magnetic resonance imaging correlation between pain and cognitive function.Methods:A total of 15 cases of 18-60 years old underwent arthroscopic surgery in adult patients,divided into preoperative chronic pain group(OG),and no chronic pain group(CG).Two groups of patients were assessed with pain score before and 3 months after operation,and 1H-MRS scans were performed using single voxel magnetic resonance spectroscopy sequence,mainly for the determination of m PFC and PAG region Nacetylaspartate(NAA),choline(Cho),creatine(Creatine,Cr)and glutamine and glutamic acid(Glx)level.Results:Preoperatively,no statistically significant differences between the two groups in metabolites of PAG and m PFC regions;Postoperatively,Glx in PAG of OG group was significantly higher than that of CG group,the metabolites relative concentration in PAG and m PFC regions had no significant difference between the groups;Glx in PAG region increased significantly in OG group after surgery(P<0.05);and Glx in PAG were slightly increased in CG group,but the difference between pre-and post-operative was not statistically significant.Conclusion: With the chronic chronic pain stimulation,PAG showed abnormal activation of the new surgical stress and pain stimulation,and lasted for a long time(3 months),suggesting that chronic pain induced dysfunction in PAG.However,in this report,the persistent increase of PAG excitatory amino acids did not lead to changes in the structure or dysfunction of m PFC.These findings suggest that long-term pain stimulation does contribute to structural and functional changes in the central nervous system,which may be a potential risk factor for cognitive impairment.But it needs for a larger sampled investigation. |
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