Department of Neurology, Teikyo University School of Medicine, Tokyo, Japan; and.
Department of Geriatrics, Neurosciences and Orthopaedics, Catholic University of the Sacred Heart, Rome, Italy.
J Clin Neurophysiol. 2023 Jul 1;40(5):450-455. doi: 10.1097/WNP.0000000000000898. Epub 2021 Oct 1.
The difference in muscle ultrasound (MUS) characteristics in primary axonal degeneration and demyelination has not been well established. The authors aimed to investigate the subject based on the correlation between MUS findings (echo intensity and muscle thickness) and compound muscle action potential (CMAP) amplitude in amyotrophic lateral sclerosis (ALS) and chronic inflammatory demyelinating polyradiculoneuropathy.
Fifteen patients with ALS and 16 patients with chronic inflammatory demyelinating polyradiculoneuropathy were examined. For each patient, echo intensity and muscle thickness of the abductor pollicis brevis, abductor digiti minimi, and first dorsal interosseous muscles were investigated. Compound muscle action potential amplitudes were measured by median and ulnar nerve conduction studies.
In total, 45 muscles were evaluated in each group. The ALS group showed a linear correlation between the MUS finding and CMAP amplitude (rs = -0.70 and 0.59 for echo intensity and muscle thickness, respectively), whereas the chronic inflammatory demyelinating polyradiculoneuropathy group showed a weaker correlation than the ALS group (rs = -0.32 for echo intensity and rs = 0.34 for muscle thickness).
The relationship between MUS abnormalities and CMAP amplitude showed different tendencies in ALS and chronic inflammatory demyelinating polyradiculoneuropathy. The results suggested that MUS abnormalities substantially reflect the muscle function in primary axonal degeneration, whereas a discrepancy between MUS findings and muscle function can be frequently seen in demyelination; specifically, MUS findings tend to be normal even though CMAP showed a reduction. These tendencies originating from underlying pathophysiology should be considered when MUS findings are used as biomarkers of disease severity.
原发性轴索性变性和脱髓鞘病变的肌肉超声（MUS）特征差异尚未得到充分证实。作者旨在基于肌电图（CMAP）振幅与肌电图（MUS）发现（回声强度和肌肉厚度）之间的相关性，研究肌萎缩侧索硬化症（ALS）和慢性炎症性脱髓鞘性多发性神经病中的这一问题。
对 15 例 ALS 患者和 16 例慢性炎症性脱髓鞘性多发性神经病患者进行了检查。对每位患者，检查了拇短展肌、趾短展肌和第一骨间背侧肌的回声强度和肌肉厚度。通过正中神经和尺神经传导研究测量复合肌肉动作电位幅度。
共评估每组 45 块肌肉。ALS 组的 MUS 发现与 CMAP 幅度之间呈线性相关（回声强度和肌肉厚度的 rs 值分别为-0.70 和 0.59），而慢性炎症性脱髓鞘性多发性神经病组的相关性弱于 ALS 组（回声强度的 rs 值为-0.32，肌肉厚度的 rs 值为 0.34）。
ALS 和慢性炎症性脱髓鞘性多发性神经病中，MUS 异常与 CMAP 幅度之间的关系表现出不同的趋势。结果表明，MUS 异常在原发性轴索性变性中很大程度上反映了肌肉功能，而脱髓鞘病变中可能经常出现 MUS 发现与肌肉功能之间的差异；具体而言，即使 CMAP 显示降低，MUS 发现也往往正常。在将 MUS 发现用作疾病严重程度的生物标志物时，应考虑这些源自潜在病理生理学的趋势。
