What is the hallmark of multiple sclerosis?

• A. Demyelination of neurons in the brain and spinal cord
• B. Demyelination of peripheral nerves only
• C. Degeneration of motor neurons
• D. Accumulation of beta-amyloid plaques

Answer: (A)

Multiple sclerosis is an autoimmune disease of the central nervous system. Its hallmark is demyelination of neurons in the brain and spinal cord, forming plaques that disrupt the way nerves transmit signals. This loss of myelin slows or blocks conduction along CNS pathways, leading to a wide range of neurologic symptoms that can come and go as lesions form and remyelinate. In the field, you might see vision changes or eye pain, numbness or weakness in the limbs, problems with balance or coordination, or sensory changes, often occurring in episodes separated by time and space. This CNS-specific process distinguishes MS from conditions that affect peripheral nerves, motor neurons, or amyloid plaques seen in other diseases.