Evaluation of upper trapezius electromyography in the early diagnosis of amyotrophic lateral sclerosis / 中华神经科杂志

ABSTRACT

Objective To evaluate the application of upper trapezins muscle electromyography (EMG) in the diagnosis of lower motor neuron damage in bulbar region in amyotrophic lateral sclerosis (ALS). Methods Standard EMG was recorded over upper trapezius muscle in 100 patients with ALS, 80 patients with cervical spondylotic myelopathy (CSM) and 100 normal controls. In groups of ALS and CSM,EMG was also recorded over sternocleidomastoid, rectus abdominis, first dorsal intercostals muscle and tibialis anterior muscles. Among those CSM patients, 43 patients had operations and the EMG on their trapezius muscle was examined at pre-operation and at 3 months post-operation. The parameters of EMG were analyzed between the groups. Results In ALS patients, spontaneous activity in upper trapezius EMG was detected more frequently in patients with disease duration 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 neurogenic EMG changes including abnormal spontaneous potentials and motor unit action petentials (MUAP) between trapezius and sternocleidomastoid in patients with ALS. Significant differences 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 and patients 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-operation CSM patients. Conclusion EMG in upper trapezius can assist in assessment of clinical and subclinical involvement of bulbar lower motor neurons in patients with ALS, especially at earlier stage.