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