What is the main cause of Post-Polio Syndrome?

• A. The burnout of healthy nerve cells due to overcompensation for damaged ones.
• B. Autoimmune attack on motor neurons.
• C. Bacterial infection in nerves.
• D. Degeneration of spinal cord from poliovirus.

Answer: (A)

Post-Polio Syndrome mainly arises from burnout of the surviving motor neurons that had to compensate for neurons damaged by poliovirus. In the acute illness, many motor neurons die. The remaining neurons sprout new branches to reinnervate the orphaned muscle fibers, creating larger motor units and keeping muscles functioning. This compensatory reinnervation works for a while, but it places sustained, increased stress on those neurons. Over years or decades, those overworked neurons gradually wear out or fail, leading to new weakness, fatigue, and muscle pain characteristic of PPS.

This isn’t due to a new infection or ongoing poliovirus activity, and it isn’t driven primarily by autoimmune attack. It also isn’t degeneration of the spinal cord caused by the virus itself during the initial illness.