Which statement best describes the pathophysiology of multiple sclerosis?

Which statement best describes the pathophysiology of multiple sclerosis?

• A. Autoimmune disease of the central nervous system affecting brain, spinal cord, and optic nerves with demyelination
• B. Peripheral nerve demyelination causing numbness only in limbs
• C. Degeneration of motor neurons in the spinal cord causing rapid muscle wasting
• D. A disorder of the cerebellum causing ataxia only

Answer: (A)

Multiple sclerosis is an autoimmune process within the central nervous system in which the immune system attacks myelin—the protective sheath around nerves—in the brain, spinal cord, and optic nerves. This demyelination disrupts nerve signal transmission, producing a wide range of neurologic symptoms that can come and go in relapses and remissions. Over time, demyelination can lead to axonal damage and neurodegeneration, with plaques forming in CNS white matter. This description fits best because MS specifically involves autoimmune-mediated demyelination in the CNS. Peripheral nerve demyelination occurs in conditions like Guillain-Barré syndrome, not MS. Degeneration of motor neurons in the spinal cord describes motor neuron disease such as ALS, not a demyelinating CNS process. A cerebellar disorder causing ataxia would not capture the broader CNS demyelination pattern seen in MS, though MS can involve the cerebellum among other areas.

Multiple sclerosis is an autoimmune process within the central nervous system in which the immune system attacks myelin—the protective sheath around nerves—in the brain, spinal cord, and optic nerves. This demyelination disrupts nerve signal transmission, producing a wide range of neurologic symptoms that can come and go in relapses and remissions. Over time, demyelination can lead to axonal damage and neurodegeneration, with plaques forming in CNS white matter.

This description fits best because MS specifically involves autoimmune-mediated demyelination in the CNS. Peripheral nerve demyelination occurs in conditions like Guillain-Barré syndrome, not MS. Degeneration of motor neurons in the spinal cord describes motor neuron disease such as ALS, not a demyelinating CNS process. A cerebellar disorder causing ataxia would not capture the broader CNS demyelination pattern seen in MS, though MS can involve the cerebellum among other areas.