Mills’ syndrome is a unique entity of upper motor neuron disease with N-shaped progression: Three case reports

Table 2 Differential diagnosis of Mills’ syndrome from amyotrophic lateral sclerosis and primary lateral sclerosis

	Mills’ syndrome	ALS	PLS
Upper motor neuron signs	Positive	Positive	Positive
Lower motor neuron signs	Negative	Positive	Negative
Initial site of disease onset	Unilateral lower limb	Commonly bilateral	Commonly bilateral
Progression manner	One side lower limb - the same side upper limb - contralateral lower limb - contralateral upper limb	From one segment to the others (cranial, cervical, thoracic, and lumbosacral)	Usually ascending
Bulbar involvement	Late stage	Middle or late stage	Late stage
Symmetry of the symptom	Significant asymmetry	Could be symmetric or asymmetric	Commonly symmetric
Electrophysiological examination	Non-special	Positive	Non-special
Prognosis	Uncertain, probably rapid progression	Rapid progression, poor prognosis	Relatively benign

ALS: Amyotrophic lateral sclerosis; PLS: Primary lateral sclerosis.