Does Denervation Continue with Post-Polio Syndrome?

Question: I am aware that as polio survivors recovered from the initial bout with polio, we went through a process called denervation. Does this process of losing anterior horn cells
(AHCs) and establishing new nerve pathways continue with post-polio syndrome?

A: Denervation is actually not a process but a condition of muscle that has lost its connection to a motor nerve cell body (AHC). Death of an AHC results in a process of Wallerian degeneration of nerve axons (fibers), and results in atrophied denervated muscle fibers. Partially denervated muscles are weak, whereas completely denervated muscles are paralyzed. When nerve fibers from AHCs that survived the poliovirus infection grow new sprouts, which reconnect to muscle fibers without a nerve supply, reinnervation is said to have occurred. In most polio-weakened muscles there is a lifetime process of continuing new muscle fiber denervation and new re-innervation. In post-polio syndrome, the rate of denervation exceeds the rate of reinnervation, and new weakening is experienced. Both normal aging and any ill health can slow down the process of reinnervation, which results in more denervated weakened muscle fibers. Post-polio syndrome may also result from something triggering a sudden speeding up of denervation, including new dying of AHCs.

Post-Polio Health (Vol. 25, No. 1, Winter 2009)