Which description best defines Guillain-Barré syndrome (GBS)?

• A. Demyelinating inflammatory polyradiculoneuropathy
• B. Autoimmune brainstem encephalitis
• C. Motor neuron disease with spasticity
• D. Primary muscular dystrophy

Answer: (A)

Guillain-Barré syndrome is an acute immune-mediated disorder of the peripheral nervous system in which inflammation targets the myelin sheaths of peripheral nerves and their roots, leading to demyelination. This damage to the myelin disrupts nerve conduction, producing rapidly progressive, usually symmetric weakness that often starts in the legs and ascends, with reduced or absent reflexes. The key feature here is the inflammatory demyelination of peripheral nerves and nerve roots, i.e., a demyelinating polyradiculoneuropathy.

This distinguishes it from other conditions described in the choices. Brainstem encephalitis involves the central nervous system and brainstem, not the peripheral nerves. Motor neuron disease with spasticity refers to degeneration of motor neurons with upper motor neuron signs like spasticity. Primary muscular dystrophy is a primary muscle disease, not a nerve disease. The description that best fits Guillain-Barré syndrome is the inflammatory demyelinating process of peripheral nerves and nerve roots.