Needle electromyography of the iliopsoas in the detection of polymyositis
ZHANG Lei, CHEN Na, WANG Ying, JIAN Fan, ZHANG Zaiqiang, PAN Hua
Department of Neurology / Neuromuscular Department of Neurology Center, Beijing Tiantan Hospital, Capital Medical University / China National Clinical Research Center for Neurological Diseases, Beijing 100070, China
Abstract：Objective To investigate the applicability of iliopsoas electromyography (EMG) in the diagnosis of polymyositis. Methods The clinical data on 28 patients diagnosed with polymyositis and treated in Beijing Tiantan Hospital between January 2018 and February 2019 was retrospectively analyzed, and another 20 healthy age- and gender-matched people served as the control. The spontaneous potentials and motor unit action potential (MUAP) of the iliopsoas, quadriceps femoris and deltoid were compared between the two groups. Results No spontaneous potential [positive sharp wave (PSW) or fibrillation potential] was detected in the iliopsoas muscle of the healthy controls. In patients with polymyositis, the rate of spontaneous potential in the iliopsoas was 57.14% (16/28), which was significantly higher than that of healthy controls (P<0.001). In addition, the MUAP amplitude [(424.20±82.41) μV vs. (593.93±65.49) μV,P<0.001] and duration [(9.73±2.05) ms vs. (11.26±0.42)ms, P<0.01] of the iliopsoas in patients with polymyositis was significantly decreased compared with healthy controls. In polymyositis patients, the rate of spontaneous potential in the deltoids (25.00%, 7/28) was significantly lower (P<0.05) than in the iliopsoas. Conclusions Spontaneous potentials in the iliopsoas have a more sensitivity in polymyositis, which can provide an Objective basis for clinical diagnosis.
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