Guillain-Barré syndrome is primarily a disease of which nervous system component?

• A. Cerebral cortex
• B. Spinal cord
• C. Autonomic ganglia
• D. Peripheral nerves (demyelination of the peripheral nervous system)

Answer: (D)

The key idea is that Guillain-Barré syndrome targets the peripheral nervous system. It’s an autoimmune attack that demyelinates peripheral nerves and their nerve roots, so the primary pathology lies outside the brain and spinal cord. Because the CNS is not the main site of damage, brain functions tied to the cerebral cortex are typically preserved, and the weakness pattern in GBS is due to peripheral nerve involvement rather than central lesions. Autonomic symptoms can occur when autonomic fibers are affected, but that’s a feature within the peripheral nerves rather than the defining site. So the best description is demyelination of the peripheral nerves.