ALS progressively destroys upper and lower neurons including anterior horn cells of the spinal cord, upper motor neurons of the cerebral cortex, and the motor nuclei of the brain.
How does ALS happen?
- ALS may begin when glutamate accumulates to toxic levels at synapses
- Affected motor units are no longer innervated
- Progressive degeneration of axons causes loss of myelin
- Non-functional scar tissue replaces normal neuronal tissue
- Denervation leads to muscle fiber atrophy and motor neuron degeneration.