Single Fiber Electromyography Study In Motor Neuron Disease

Dept. of Neurology, Sir Run Run Shao HospitalAffiliated to Medical School, Zhejiang UniversityPostgraduate Lv WenDirector Prof. Chen YuanshenPurpose:Motor neuron disease (MND) is a progressive neurodegenerative disorder with upper and lower motor neuron involved. According to the involved area and illness course, MND can be divided into several types, but amyotrophic lateral sclerosis(ALS) and progressive muscular atrophy(PMA) are the main types. The diagnosis of MND is dependent on clinical manifestation, without objective and specific markers of the disease. Traditional EMG has important value in diagnosis of MND. The technique of single fiber electromyography(SFEMG) was originally developed in the early 1960s by Erik Stalberg and Jan Ekstedt to record and identify action potentials(APs) from individual muscle fibers to investigate the physiology and pathophysiology of the muscle. In SFEMG, we check jitter and fiber density(FD). The degenerating and dying process of lower motor neuron is progressive in the ALS and PMA patients. The surviving muscle fibers are6reinnervated by subterminal collateral sprouting of nerve twigs from neighbouring healthy motor axons, and they appear as fiber type grouping which induced FD increase. The newly established motor end-plates are immature with safety factor decreased which induces increased jitter. So, in the ALS and PMA patients, the jitter and FD value are both increased. In our study, jitter and FD value of SFEMG are measured in MND patients, and compared with traditional EMG. We have attempted to study the diagnostic Value of SFEMG in MND.Patients and controls: (1)MND group with 38 patients. The diagnosis of MND depended on history and clinical features. The diagnostic criteria was according to the El Escorial diagnostic critetia for ALS of The World Federation of Neurology(WFN) in 1994 and a revised criteria in 1998. The traditional EMG, nerve conduction velocity, biochemical examinations and imaging studies were done in order to rule out other nerve and muscle diseases often confused with ALS and PMA. The MND group included 27 patients with ALS and 11 patients with PMA. The patients received traditional EMO and SFEMG examinations. Muscles evaluated in the traditional EMG were three limb muscles and stemocleidomastoid muscle. In the SFEMG exam, the extensor digitorum communis(EDC) muscle was checked. (2)Control group with 30 persons. It included healthy volunteers, migraine, neurosis and epilepsy patients. There was no statistical significant differences of sex and age between the two groups. In the control group, we only did the SFEMG exam.7Methods:(l)SFEMG. We used the Keypoint-2000 electromyograph of Dantec Company. The recording electrode was a special single-fiber needle electrode. We measured the jitter and FD value of EDC. We used the diagnostic criteria of Stalberg and the AAEM recommended criteria. (2)Traditional EMG. Recording electrode was concentric needle electrode. We checked four steps: insertional activity, the occurrence of abnormal spontaneous activities during relaxation, measurement of MUP during slight voluntary contraction of muscle and recruitment potentials during forced contraction of muscle. The diagnostic criteria was according to the EMG department of Beijing Union Hospital. (3)Nerve conduction velocity measurement. (4)Statistical analysis.Results:1.The mean MCD of the MND group was 88.42?0.4ips. Compared with the control group 3O.40?.05~s, there was statistical difference between two groups(P<0.0O 1). The mean FD value of the MND group was 2.84?.69. Compared with control group 1.33+0.11, there was statistical difference(P<0.00 1).2.There were no statistical differences between PMA and ALS patients in mean MCD and FD values(83.00?6.Olp.s vs 90.03?2.22p.s, 2.76+0.59 vs 2.88+0.74).3.There was no relationship between mean MCD, FD value and duration of illness (r10.0 13, r20.001, P>0.05).4. In the MND group, the positive rate...