What pathophysiological processes in the nervous system lead to the symptoms seen in amyotrophic lateral sclerosis (ALS)?

All answers are correct: A) Accumulation of misfolded proteins: ALS is characterized by the abnormal accumulation of misfolded proteins, such as TDP-43 and SOD1, within motor neurons. These misfolded proteins can disrupt cellular function, leading to impaired protein degradation mechanisms and ultimately contributing to motor neuron degeneration. B) Muscle atrophy: Progressive muscle atrophy is a hallmark feature of ALS, resulting from the degeneration and loss of motor neurons that innervate skeletal muscles. Without proper neuronal input, muscles waste away due to lack of stimulation and support. C) Neuronal degeneration: The degeneration of motor neurons in the brain and spinal cord is a key pathological feature of ALS. This neuronal loss disrupts the communication between the brain and muscles, leading to muscle weakness and eventual paralysis. D) Motor neuron loss: The progressive death of motor neurons is central to the pathogenesis of ALS. As motor neurons degenerate and die, the muscles they innervate lose their ability to function, resulting in the characteristic motor symptoms of ALS.