Table 1.

Common pathological features in motor neurons and the skeletal muscle in ALS.

Common Pathological Features
	ALS
Structural	Motor neurons	Skeletal muscle
Decreased innervation	+ (axonopathy)	+ + +
NMJ dismantlement (fragmentation & loss)	+ + + (pre-synaptic)	+ + + (post-synaptic)
Reduced mass and strength / atrophy	+ + + (spinal cord)	+ + +
Cytoplasmic & nuclear aggregates	+ + +	+ +
	ALS
Functional	Motor neurons	Skeletal muscle
Metabolic changes	+	+ + +
Oxidative stress	+ + +	+ +
Deregulated nutrient sensing	+	+ +
Loss of proteostasis	+ + +	+ +
Mitochondriopathy	+ +	+
DNA damage	+ +	+
Inflammation	Neuroinflammation	+
Altered intercellular communication	+ +	+
Cellular senescence	+ +	+ (in vitro)
Cell death	+ + +	+ +

Abbreviations: +, low grade; + +, medium grade; + + +, high grade; NA, not applicable.