In Parkinson's disease, which statement best describes the condition?

In Parkinson's disease, which statement best describes the condition?

• A. Peripheral nerve disease affecting myelin
• B. Chronic progressive disease of CNS with degeneration of dopaminergic substantia nigra neurons and nigrostriatal pathways
• C. Acute inflammatory demyelinating polyneuropathy
• D. Motor neuron disease with upper and lower motor neuron signs

Answer: (B)

Parkinson's disease is a chronic, progressive neurodegenerative disorder of the central nervous system. It primarily involves degeneration of dopaminergic neurons in the substantia nigra pars compacta, leading to reduced dopamine in the nigrostriatal pathway. This loss disrupts basal ganglia circuits, producing the hallmark motor features—bradykinesia, resting tremor, rigidity, and impaired postural stability—with progression over time. The pathology often includes Lewy bodies (alpha-synuclein deposits). This description fits a chronic CNS disease with dopaminergic neuron loss in the substantia nigra and nigrostriatal pathways, and it does not describe a peripheral nerve demyelinating condition, an acute inflammatory polyneuropathy, or a motor neuron disease like ALS.

Parkinson's disease is a chronic, progressive neurodegenerative disorder of the central nervous system. It primarily involves degeneration of dopaminergic neurons in the substantia nigra pars compacta, leading to reduced dopamine in the nigrostriatal pathway. This loss disrupts basal ganglia circuits, producing the hallmark motor features—bradykinesia, resting tremor, rigidity, and impaired postural stability—with progression over time. The pathology often includes Lewy bodies (alpha-synuclein deposits). This description fits a chronic CNS disease with dopaminergic neuron loss in the substantia nigra and nigrostriatal pathways, and it does not describe a peripheral nerve demyelinating condition, an acute inflammatory polyneuropathy, or a motor neuron disease like ALS.