Neurons “Sprouting”
Dr. Bruno’s Original Post:
A new study found in fruit flies what’s been known for 70 years to happen in polio survivors . . .
“What happens when a neuron dies? Can other neurons around it pick up the slack to maintain the same level of function? In the fruit fly, each muscle is activated by two motor neurons. Researchers wondered what would happen if one neuron were removed. Would the other neuron compensate for this loss? They found that the remaining neuron expanded its synaptic arbor (“sprouted”) and compensated for its missing neighbor.” Source
FROM The Polio Paradox :
“Axons Sprouts and Fat Fibers. Remaining, poliovirus-damaged motor neurons did something amazing after the poliovirus infection had run its course. The axons grew, sending out sprouts -- like extra telephone lines -- to turn on the muscles that were orphaned when their motor neurons were killed. Those sprouts took from nine months to 2 years to grow and ultimately activated about 16 times more muscle fibers than were connected to the motor neuron originally.”
“Yet another important process took place that allowed polio survivors to regain strength. Muscle strengthening exercise and physical therapy caused muscle fibers to grow larger, a process called hypertrophy, enabling the fibers to do more work. Polio survivors' individual muscles fibers have been found to be twice the size of fibers in those who didn't have polio. So, motor neuron recovery, sprouting and muscle fiber hypertrophy allowed polio survivors to get stronger after the poliovirus attack. A 1955 study by British polio pioneer W.J.W. Sharrard found that polio survivors regained nearly 95% of the strength they would ever recover during the first 11 months after the polio attack as a result of sprouting, muscle fiber hypertrophy and learning to use functioning muscles to substitute for those that were permanently paralyzed.”
“So, where do you stand (or sit) today with regard to your post-polio motor neurons? If you had any paralysis, muscles that you know were affected during the poliovirus attack have on average only 40% of the motor neurons you were born with, neurons that were damaged, are smaller than normal, whose internal “pipes” are clogged, but have sprouted to turn on 16 times more muscle fibers, fibers that are twice the size they were before you had polio. If you have muscles that were not paralyzed or had so-called "non-paralytic" polio, you lost 40% of the motor neurons you were born with, neurons that were damaged and are also smaller, clogged, over sprouted and overworked.”
BOTTOM LINE: “Save Your Sprouts!”
More information is available under the topic: “Muscle Pain/Weakness” in the Encyclopedia of Polio and PPS.