How can poliomyelitis be distinguished clinically from Guillain-Barré syndrome?

• A. GBS is symmetric; poliomyelitis asymmetric.
• B. Poliomyelitis often shows asymmetric, focal paralysis with preserved sensation early; GBS symmetric ascending weakness.
• C. Poliomyelitis always symmetric.
• D. GBS never involves cranial nerves.

Answer: (B)

The pattern of weakness and what happens to sensation is the key difference. Poliomyelitis primarily damages the motor neurons in the spinal cord (anterior horn cells), so it tends to cause focal, asymmetric muscle weakness in one limb or a small group of muscles. Sensation is generally preserved early because sensory pathways are spared. Guillain-Barré syndrome, on the other hand, is an immune-mediated attack on peripheral nerves that usually hits many nerves more or less at once, leading to symmetric, ascending weakness and reduced or absent reflexes, with sensory symptoms or paresthesias more common than in polio. So, a localized, asymmetric paralysis with preserved sensation points to poliomyelitis, while a symmetric, ascending weakness with diminished reflexes points to Guillain-Barré syndrome.