Which statement best describes classic clinical signs of paralytic poliomyelitis on examination?

• A. Acute onset flaccid weakness, asymmetric paralysis, hyporeflexia or areflexia, with preserved sensation
• B. Spastic paralysis with hyperreflexia
• C. Bilateral symmetric weakness with heightened sensation
• D. Seizures

Answer: (A)

Paralytic poliomyelitis classically shows damage to the motor neurons of the spinal cord and brainstem (anterior horn cells), leading to lower motor neuron signs. On exam you’ll observe sudden, focal weakness in one or more limbs with a flaccid (soft) paralysis, diminished or absent deep tendon reflexes, and little or no sensory loss. The involvement is usually asymmetric and the sensation remains intact because the virus spares the sensory pathways. This combination—acute onset of flaccid weakness with reduced reflexes and preserved sensation—is the hallmark. Some patients may also have fasciculations and later muscle atrophy. In contrast, patterns with spasticity and hyperreflexia point to upper motor neuron involvement, bilateral symmetric weakness with sensory changes isn’t typical of poliomyelitis, and seizures are not characteristic of the motor neuron damage seen in polio.