Table 1.

The overlapping clinical taxonomies of MND (ALS)

LMN versus UMN spectrum	Pure LMN ALS (progressive muscular atrophy)	LMN-predominant ALS	Classical ALS (mixed LMN and UMN signs)	UMN-predominant ALS	Pure UMN ALS (primary lateral sclerosis)
Sites of initial symptom onset	Upper limb Lower limb	Upper limb Lower limb(Respiratory)	Upper limb Lower limb Bulbar(Cognitive)(Respiratory)	Upper limb Lower limb Corticobulbar	Lower limb Corticobulbar
Regional phenotypes	Pseudopolyneuritic (Patrikios’)	Flail arm or leg	ALS-FTD	Progressive bulbar palsy
Rate of progression	+	++	+++	++	+

ALS = amyotrophic lateral sclerosis; FTD = frontotemporal dementia; LMN = lower motor neuron; MND = motor neuron disease; UMN = upper motor neuron