Onset and spreading patterns of upper and lower motor neuron symptoms in ALS

Amyotrophic lateral sclerosis (ALS) is a fatal rapidly progressive adult-onset neurodegenerative disorder characterized by the progressive degeneration of upper and lower motor neurons. It has been debated whether „dying forward“ mechanisms originating in the primary motor cortex and/or „dying back“ phenomena starting in the lower motor neurons occur in ALS since the disease has first been described by Jean Martin Charcot in 1874. Ravits et al. have previously analyzed the distribution of upper and lower motor neuron degeneration in the early disease period and concluded that this is a focal process which advanc…