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

To explore differential diagnosis value of dissociated lower-limb muscle impairment, we performed a retrospective analysis of clinical and electrophysiological features in 141 lower-limb involved ALS patients, 218 normal controls, 67 disease controls, and 32 lumbar spondylosis disease patients. The dissociated lower-limb muscle impairment was quantified by plantar flexion and dorsiflexion strength, compound muscle action potentials ratio of peroneal and tibial nerves (split index, SI) and semi-quantitative scoring scale of denervation potential. Clinical features: the proportion of decreased dorsiflexion was higher than decreased planter flexor strength in lower-limb involved ALS (77.2%vs 38.3%). Electrophysiological features: (1) SI in ALS was the lowest among four groups (Test statistic = 40.57, p 2 = 87.12, p