Guillain-Barré syndrome primarily affects which component of the nervous system?

• A. Peripheral nerves (demyelination)
• B. Cerebral cortex
• C. Spinal cord
• D. Autonomic ganglia

Answer: (A)

Guillain-Barré syndrome is an autoimmune attack on the peripheral nervous system, causing demyelination of peripheral nerves. This means the myelin sheaths that insulate nerves outside the brain and spinal cord are damaged, leading to weakness and areflexia that usually starts in the legs and ascends upward. The central nervous system—brain (cerebral cortex) and spinal cord—is not the primary target, so those structures are typically spared. Autonomic symptoms can appear because autonomic nerves are also peripheral, but the defining process is peripheral nerve demyelination, not involvement of central components.