What best describes amyotrophic lateral sclerosis (ALS)?

• A. Autoimmune disease causing demyelination of the peripheral nerves
• B. Progressive neurological disease with neuron death leading to muscle weakness and paralysis
• C. Acute infection of the brain causing seizures
• D. Degeneration of the optic nerve leading to vision loss

Answer: (B)

ALS is a progressive motor neuron disease in which the neurons that control voluntary muscles—both in the brain and spinal cord—gradually die, leading to muscle weakness and eventual paralysis. Because it affects motor neurons, you see signs from both the upper motor neurons (such as spasticity and brisk reflexes) and the lower motor neurons (such as fasciculations and muscle atrophy). Sensation is typically preserved, and cognitive changes can occur in some cases, but the hallmark is the relentless loss of muscle function, including respiratory muscles as the disease progresses. There is no cure, and management centers on slowing progression, maintaining function, and providing supportive care, with medications like riluzole or edaravone offering some benefit for certain patients. The other descriptions refer to different conditions—an autoimmune demyelinating process of peripheral nerves, an acute brain infection, or optic nerve degeneration causing vision loss—none of which capture the typical motor-neuron–driven weakness and eventual paralysis seen in ALS.