Which of these is not a progressive disease of the CNS?

Stroke is classified as an acute event rather than a progressive disease of the central nervous system (CNS). It occurs when blood supply to part of the brain is interrupted or reduced, preventing brain tissue from getting necessary oxygen and nutrients. Depending on the severity and location of the stroke, there can be sudden and often permanent impairments, but this is not characterized by a gradual decline over time, which is the nature of progressive diseases.

In contrast, Alzheimer's disease, multiple sclerosis, and Parkinson's disease are all considered progressive conditions. Alzheimer's disease typically leads to a gradual decline in cognitive functions, memory loss, and eventual loss of independence. Multiple sclerosis involves a progressive deterioration of nerve function due to the immune system attacking the protective myelin sheath around nerve fibers. Parkinson's disease is characterized by progressive motor symptoms, including tremors, rigidity, and bradykinesia, due to the degeneration of dopamine-producing neurons in the brain.

Thus, the focus on progression over time clearly differentiates stroke from the other listed conditions.