What characterizes Guillain-Barré syndrome?

• A. Chronic progressive weakness
• B. Acute inflammatory demyelinating polyneuropathy with ascending weakness and areflexia after infection
• C. Nerve tumor
• D. Myasthenia gravis

Answer: (B)

Guillain-Barré syndrome arises from an autoimmune attack on the peripheral nerves after a recent infection. The defining features are acute, rapidly evolving weakness that starts in the legs and moves upward (ascending), often symmetric, with absent or diminished reflexes (areflexia). The underlying pathology is demyelination of peripheral nerves, which disrupts nerve conduction and explains the progressive weakness and sensory symptoms. This is a post-infectious, inflammatory process and tends to evolve over days to weeks, unlike chronic progressive weakness in some neuropathies or neuromuscular junction disorders like myasthenia gravis. Recognizing the post-infectious trigger, the timeline, the ascending pattern of weakness, and the loss of reflexes helps differentiate Guillain-Barré syndrome from other conditions.