Table 1.

Clinical phenotypes, symptoms, and prognosis of amyotrophic lateral sclerosis (ALS).

Clinical Phenotypes	Regions	Symptoms	The Prognosis
Limb-onset	UMN	Spasticity, weakness, and brisk deep tendon reflexes;	Overall survival is 5–8 years
	LMN	fasciculations, wasting, and patients present with gradually ascending distal weakness.
Bulbar-onset	UMN	Spastic dysarthria, which is characterized by slow, labored, and distorted speech, often with a nasal quality;	2 to 4 years, and depends on the timing of respiratory and limb involvement.
	LMN	tongue wasting, weakness, and fasciculations, accompanied by flaccid dysarthria*, and later dysphagia.
Primary lateral sclerosis	Pure UMN	It is characterized by an ascending spastic tetraparesis with involvement of speech in the majority by 3 years, urinary urgency;	A slowly progressive condition, with survival for decades.
Progressive muscular atrophy	Pure LMN	The least well-defined subtype of ALS. Asymmetrical weakness and wasting, often in the legs, which coalesces into four limb lower motor neuron involvement.	About 5 years
ALS-frontal lobe dementia syndrome (frontotemporal lobar degeneration, FTLD)	UMN, LMN, and brain cortex	Presentation with frontotemporal dementia. Later developing signs of MND.	An overall survival of less than 3 years.

UMN-upper motor neurons, LMN - Lower motor neuron.