Which CNS disease is characterized by damage to the myelin sheath causing tremor, weakness, and disturbances in vision and speech?

• A. Alzheimer's disease
• B. Parkinson's disease
• C. Amyotrophic Lateral Sclerosis
• D. Multiple Sclerosis

Answer: (D)

The main idea is a disease of the central nervous system where the myelin sheath is damaged, slowing or blocking nerve signals and producing diverse neurologic symptoms. In multiple sclerosis, the immune system attacks myelin in the CNS, leading to plaques that disrupt communication between the brain and the rest of the body. The combination of tremor, weakness, and disturbances in vision and speech fits MS well because optic nerves can be affected (causing vision changes), motor pathways can be impaired (causing weakness and tremor), and cerebellar or bulbar pathways can produce speech difficulties. Other conditions listed have different primary patterns: Alzheimer's mainly affects memory and cognition; Parkinson's shows resting tremor, bradykinesia, rigidity; ALS involves progressive motor neuron degeneration with muscle weakness and atrophy. The described mix of visual problems plus motor and speech symptoms is characteristic of a CNS demyelinating disease like multiple sclerosis.