Evaluation of uppertrapezius electromyography in the early diagnosis of amyotrophic lateral sclerosis

Abstract

：Objective To evaluate the application of upper trapezinsmuscle electromyography (EMG) in the diagnosis of lower motor neuron damage in bulbarregion in amyotrophic lateral sclerosis (ALS). Methods Standard EMG was recorded overupper trapezius muscle in 100 patients with ALS, 80 patients with cervical spondyloticmyelopathy (CSM) and 100 normal controls. In groups of ALS and CSM,EMG was also recordedover sternocleidomastoid, rectus abdominis, first dorsal intercostals muscle and tibialisanterior muscles. Among those CSM patients, 43 patients had operations and the EMG ontheir trapezius muscle was examined at pre-operation and at 3 months post-operation. Theparameters of EMG were analyzed between the groups. Results In ALS patients, spontaneousactivity in upper trapezius EMG was detected more frequently in patients with diseaseduration equal to or less than 8 months than the others (21/30(70%) vs 28/70(40%), X~2=7.56, P=0.004). There was no difference in neurogenicEMG changes including abnormal spontaneous potentials and motor unit action petentials(MUAP) between trapezius and sternocleidomastoid in patients with ALS. Significantdifferences in MUAP were noted between ALS patients((1086.9±152.6)μV, (17.2±6.5) ms,23.6%±3.4%) and controls ((606.7±82.7)μV,(11.6±1.8)ms,12. 8%±2.2%;q=9.27, 4.57, 4.12, all P<0.01), and between patients with ALS andpatients with CSM ((615.7±90.3) μV,(12.1±2.0) ms,13.5%±2.4%,q=8.32,4. 25, 4. 23, all P< 0. 01). Few spontaneous activities in trapezius EMG were detected in post-operationCSM patients. Conclusion EMG in upper trapezius can assist in assessment of clinical andsubclinical involvement of bulbar lower motor neurons in patients with ALS, especially atearlier stage. Key words: Amyotrophic lateral sclerosis; Cervical spondylosis; Electromyography; Back; Muscles