Studies On The Condition Of Application And Diagnostic Value Of Electromyography

Background:The diagnostic ability and research in neuroelectrophysiology in China have progressed a lot in recent years; the academic standard has reached global level. Have electrodiagnostic tests played its role in clinic? How to make it work more efficiently? Figuring out the application status of neuroelectrophysiological tests in China and collecting the baseline data plays an important role on the further work and the standardized application of EMG. The analysis of the application status and diagnostic value of electromyography is blank in China. As one of the famous EMG laboratory in China, PUMCH accumulates huge amount of neurophysiologic and clinical data, which is the foundation of this large sample retrospective experiment.Objectives:Through the retrospective analysis of clinical and neurophysiological data of PUMCH to establish the baseline information of EMG application, analyze the diagnostic value of EMG and the correlation between clinical symptoms, signs, and electrophysiology.Methods:Select all the patients who underwent needle EMG, nerve conduction study, repetitive nerve stimulation and skin sympathetic response test in PUMCH from2008to2010to retrospective analyze the clinical and neurophysiological information, establish the database, and compare with that from1993to2003. The survey includes general situation, the clinical situation, the relevant previous histories, related auxiliary tests, diagnosis, electrophysiological results, and the relationship between clinical and electrophysiology.Results:1) The number of patients examined and positive rate in different years were3097(62.8%) from1993to1995,6455(60.7%) from2001to2003,10161(48.9%) from2008to2010.2) The positive rates in EMG results of different first symptoms were68.1%for motor symptom,67.2%for concomitant motor and sensory symptom,49%for sensory symptom,31.9%for unclassified symptom,30.7%for no symptom and sign. The positive rate of EMG were38.5%for those with sensory symptom only and69.3%for those with both sensory symptoms and signs (P<0.05).3) In all patients performed needle EMG,39.5%was neurogenic lesion,7.9%was myogenic lesion, and1.5%was concomitant neurogenic and myogenic lesion.546patients showed diffuse neurogenic changes on EMG, including400(73.3%) patients with MND/ALS,19with cervical spondylosis combined with lumbar spondylosis,10with spinal muscular atrophy,9with Charcot-Marie-Tooth disease,9with Hirayama disease,7with Kennedy’s disease,3with multiple motor neuropathy and7with other diseases,82patients with no definite diagnosis.704patients showed multiple peripheral neuropathy changes on EMG, including246patients with diabetic polyneuropathy,43with CMT/HMSN,36with connective tissue disease,43with AIDP,22with POEMS syndrome,16with CIDP,7with paraneoplastic syndrome and29with other diseases,262with no definite diagnosis.4) EMG results of4688patients were consistent with the initial clinical diagnosis, of which28.5%(1339/4688) showed normal EMG. EMG results of2822patients were different from initial clinical diagnosis, of which71.2%(2010/4688) showed normal EMG results. In those with abnormal EMG results, EMG results of250patients were consistent with the symptoms, but they were different from the initial diagnosis, EMG results of411patients had no relevant to the initial diagnosis and symptoms, while only151patients had unexpected positive results who were misdiagnosed to functional disorders.Conclusions:1) The number of patients performed EMG has been increasing during the past years; however the positive rate of EMG is decreasing.2) The positive rate of EMG changes with different symptoms and signs at onset. Performing EMG test on those who only have sensory symptoms and screening for the potential neuromuscular diseases are the reasons for decreasing positive rate.3) EMG plays an important role in clinical diagnosis, but the excessive use of it should be concerned.4) Different diseases can show the same EMG results and different EMG results can be detected in the same disease.37.6%of EMG results are irrelevant with clinical situation. EMG result should be explained with clinic and other auxiliary tests together to get a proper diagnosis.