Paralytic poliomyelitis is most clearly identified by which feature?

• A. Acute flaccid paralysis
• B. Seizures
• C. Chronic pain
• D. Sensory loss

Answer: (A)

Paralytic polio is defined by acute onset of focal, asymmetric, flaccid paralysis due to destruction of motor neurons in the anterior horn cells of the spinal cord (often with brainstem involvement). This motor neuron injury causes weakness with decreased tone and areflexia, and muscle wasting can follow, while sensation is typically preserved because the sensory pathways are not affected. That preserved sensation with sudden weakness is the hallmark that sets paralytic polio apart from other conditions. Seizures and chronic pain aren’t characteristic features, and sensory loss is not expected in polio.