OBJECTIVE To identify a novel physiologic marker of bulbar motor involvement in amyotrophic lateral sclerosis (ALS) based on jaw muscle synergies. METHODS Muscle synergies were extracted from the surface electromyographic recordings of five jaw muscles during speech in 11 individuals at the prodromal or symptomatic stages of bulbar ALS and 10 neurologically-healthy controls, using non-negative matrix factorization. The disrupted muscle synergies in ALS were identified; their efficacy in differentiating individuals with ALS from healthy controls and relation to the previously-reported kinematic and functional speech deficits were determined. RESULTS An antagonist synergy (i.e., masseter × digastric) was significantly disrupted in ALS, which differentiated individuals with ALS from healthy controls with 82% sensitivity and 90% specificity. Such a disruption occurred prodromally and was associated with slowed jaw movement and reduced speaking rate across the range of severity. CONCLUSIONS The disruption of jaw antagonist synergy in ALS likely reflects the impact of impaired neural drive on the coordinative functioning of bulbar muscles, which may be used to assess bulbar motor involvement. SIGNIFICANCE Jaw antagonist synergy shows promise as a novel physiologic marker of bulbar motor involvement in ALS, which has the potential to serve as a quantitative measurement tool for bulbar assessment.

中文翻译：

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肌萎缩侧索硬化症中延髓运动受累的新生理标志物：下颌肌肉协同作用

目的 确定基于颌肌协同作用的肌萎缩侧索硬化症（ALS）中延髓运动受累的新生理标志物。方法 使用非负矩阵分解，从 11 名处于延髓 ALS 前驱或症状阶段的个体和 10 名神经系统健康对照者讲话时的 5 块颌部肌肉的表面肌电图记录中提取肌肉协同作用。确定了 ALS 中被破坏的肌肉协同作用；确定了它们将 ALS 患者与健康对照者区分开来的功效以及与先前报告的运动学和功能性言语缺陷的关系。结果 ALS 中拮抗剂的协同作用（即咬肌 × 二腹肌）被显着破坏，它以 82% 的敏感性和 90% 的特异性将 ALS 个体与健康对照区分开来。这种中断发生在前驱期，并与下颌运动减慢和严重程度范围内的语速降低有关。结论 ALS 中颌骨拮抗剂协同作用的中断可能反映了神经驱动受损对延髓肌肉协调功能的影响，可用于评估延髓运动受累。意义下颌拮抗剂协同作用有望作为 ALS 中延髓运动受累的新型生理标志物，它有可能作为延髓评估的定量测量工具。可用于评估延髓运动受累。意义下颌拮抗剂协同作用有望作为 ALS 中延髓运动受累的新型生理标志物，它有可能作为延髓评估的定量测量工具。可用于评估延髓运动受累。意义下颌拮抗剂协同作用有望作为 ALS 中延髓运动受累的新型生理标志物，它有可能作为延髓评估的定量测量工具。