Quantifying the split-elbow sign: a comprehensive study in amyotrophic lateral sclerosis - He, Sheng-Yi; Cai, Wei-Chen; Su, Wei-Ming; Duan, Qing-Qing; Jiang, Zheng; Yin, Kang-Fu; Gu, Xiao-Jing; Chen, Yong-Ping; Cao, Bei (Frontiers in Neurology, 2024)