Dissociated lower limb muscle involvement in amyotrophic lateral sclerosis and its differential diagnosis value

= 87.12, p < 0.001). ROC curve: the SI cutoff was 0.52 and 0.33 respectively to differentiate ALS from lumbar spondylosis disease and peripheral neuropathy. Lower-limb involved ALS patients exhibited "split leg" phenomenon. The SI value could be used as an electrophysiological marker to differentiate ALS from lumbar spondylosis disease and peripheral neuropathy.