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The Early Evaluation Of Motor Nerve Fiber In Diabetic Peripheral Neuropathy

Posted on:2015-02-13Degree:DoctorType:Dissertation
Country:ChinaCandidate:L TianFull Text:PDF
GTID:1224330503952021Subject:Neurology
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Objective In this study, two neurophysiological techniques, including single-fiber conduction study(SF-CS) and motor unit number estimate(MUNE), were investigated to detect early motor nerve myelination and axonal function status in patients with diabetes mellitus.We dynamiclly observed the changes of ultrastructure and myelin basic protein, neurofilament protein expressed in sciatic nerve of rats with diabetes mellitus,which provides objective evidence of peripheral nerve damage.With the results obtained,we evaluated the contribution of MUNE and SF-CS on early detection of motor fiber damage in patients with DPN.Methods The study included two parts: clinical study and animal experiment.1 Clinical study. 80 patients with DM and 29 age-matched normal subjects were enrolled in the study, using the WHO(world health orgnization) diagnostic criteria for DM. Patients with DM were divided into three groups according to the nerve conduction abnormality of peroneal nerve by conventional nerve conduction detection. The normal DM group included 27 patients with normal conduction.The paresthesia group included 27 patients with abnormal sensory conduction.The admixture group included 26 patients with both abnormal motor and abnormal sensory conduction.The MUNE of extensor digitorum brevis, peroneal nerve motor nerve conduction studies and SF-CS of peroneal nerve were separately performanced by applying the electromyogram device of Keypoint 4. Detection parameters for SF-CS are the single-fiber conduction velocity(SF-CV) and the single-fiber distal motor latency,(SF-DML).Peroneal nerve motor nerve conduction study used motor nerve conduction velocity(MCV), distal motor latency(DML) and compound motor active potential(CMAP) as test parameters.We compared SF-CV, SF-DML, MCV, DML, among four groups to evaluate peripheral nerve myelin function.MUNE and CMAP were also compared to assess peripheral nerve axon function.We also invested the relationship between SF-CV、SF-DML、MUNE and the duration of DM,levels of fasting blood glucose and Hb Alc.2 Animal experiment. Male rats were randomly divided into control group and DM group. Diabetic rat model were induced with intraperitoneal injections of STZ. At the end of the 4th week, 8th week and 12 th week after onset of hyperglycemia, rats were anesthetized and SF-CS(SF-CV, SF-DML), motor conduction(MCV, DML, CMAP) of the sciatic nerve and MUNE of gastrocnemius muscle were performanced by using the electromyogram device of Keypoint 4. The ultrastructure of sciatic nerve was observed by a electron microscope. At the end of the 8th week and 12 th week after onset of hyperglycemia, the expression of myelin basic protein(MBP)and neurofilament protein(NF) in sciatic nerve of both groups was observed by immunohistochemistry technique.Results 1 The SF-CV,SF-DML,MCV,DML,CMAPof peroneal nerve and extensor digitorum MUNE of DM normal group had no significant difference with the normal subjects(P>0.05).The paresthesia group had lower extensor digitorum brevis MUNE than those of normal subjects,(95.15±32.31)VS(141.44±53.78,P<0.01)and lower peroneal nerve SF-CV(43.84±2.99m/s)VS(46.78±3.64m/s,P<0.01). The SF-DML,MCV,DML, CMAP of peroneal nerve paresthesia group had no significant difference with the normal subjects(P>0.05).The admixture group had lower extensor digitorum MUNE(35.58±19.82)and peroneal nerve SF-CV(35.32±3.35m/s), CMAP(2.34±1.13 m V),MCV(41.13±3.13 m/s)and prolonged SF-DML(4.49±0.75ms),DML(4.16±0.77ms)than the other three groups(P<0.01).2 There were significant negative correlations between duration of DM and extensor digitorum brevis MUNE(r=-0.337,P=0.002)and peroneal nerve SF-CV(r=-0.225,P=0.045).But no evident correlation was found with MUNE and fasting blood glucose(r=-0.069,P=0.543)and Hb Alc(r=-0.182,P=0.106). SF-CV had no correlation with fasting blood glucose( r=-0.201, P=0.073) and Hb A1c(r=-0.199,P=0.076).SF-DML had no correlation with duration of DM(r=0.125,P=0.271), fasting blood glucose(r=-0.196,P=0.081)and Hb Alc(r=0.180,P=0.109).3 80.7% of rats treated with STZ demonstrated the clinical manifestations of DM eventually. At the end of the 4th week after the onset of hyperglycemia, DM group rats showed a decreased MUNE of gastrocnemius muscle compared to normal rats(275.88±87.87)VS(369.71±75.64,P<0.05). At the end of the 8th week after the onset of hyperglycemia,compared with normal rats,MUNE of gastrocnemius muscle, sciatic nerve SF-CV were reduced,sciatic nerve SF-DML were prolonged in DM group rats(P<0.05),while MCV,DML,CMAP of gastrocnemius muscle had no significant difference with the normal rats. At the end of the 12 th week after the onset of hyperglycemia,DM group rats had lower MUNE of gastrocnemius muscle, sciatic nerve SF-CV,MCV,CMAP than those of normal rats. The expression of MBP,NF in sciatic nerve of DM group were decreased at the end of the 8th and 12 th week.Sciatic nerves of rats from DM group of 4wk,8wk,12 wk were investigated by electron microscope and we observed that part of diabetic nerves performanced myelin lamellar structure loose and damage of axon at 4wk.Using high magnification the electron microscopy showed myelin lamellar structure loose at 8wk and 12 wk, the separations between the axon and myelin sheath in the nerve were obvious, vascular degeneration and the ring-shaped formation and swelling pressure on the axon. microfilaments and microtubules were damaged, and schwann cell swelled.Conclusions 1 MUNE and SF-CV were much earlier to detect early motor nerve dysfunction in DM patients than conventional nerve conduction studies.SF-CV and MUNE are slower with the increasing duration of diabetes.SF-DML had no correlation with the duration of diabetes, fasting blood glucose, Hb A1 c.2 At 4 wk after the onset of hyperglycemia, we observed ultrastructure damage of peripheral nerves by electron microscope in DM rats. The damage get more severe with prolonging duration of DM.DM group rats showed a decreased MUNE of gastrocnemius muscle indicating early axonal dysfunction. SF-CV, SF-DML and the expression of MBP and NF in sciatic nerve of DM group decreased at 8wk. MCV, DML, CMAP of sciatic nerve in DM group decreased at 12 wk. These results proved that MUNE and SF-CS may contributed to earlier detection of DPN axons, myelin dysfunction than motor nerve conduction study.
Keywords/Search Tags:diabetic peripheral neuropathy, motor nerve, single-fiber conduction study, motor nerve conduction study, motor unit number estimate, electron microscopy, myelin basic protein, neurofilament protein
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