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Wallerian degeneration below injury site?

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  • Wallerian degeneration below injury site?

    Since servered axon will undergo Wallerian degeneration, does This mean spinal cord beneath the injury site is ultimately screwed? i.e for complete cervical injury to walk, the axon have to regrow allll the way below injury site to the waist and reconnect with lmn?

  • #2
    Yes, probably, but also no.

    Sorry for the confusing response, but that really is the answer.

    It is possible that some neurons will have to grow all the way from the brain down to lower motor neurons to re-establish a connection to muscles to allow movement. This would also be the case for sensation - sensory neuron branches may have to grow all the way back up to the brain.

    It is also possible, however, for certain types of neurons, called propriospinal neurons, to branch out and build bridges between upper motor neurons that come from the brain/brainstem, and lower motor neurons. This has been documented in animal SCI, and it is believed that this is one of the ways that people can recover some motor function after SCI. I believe propriospinal neurons can also play a role in sensory recovery, but I'm not 100% positive.

    So depending on the extent of the injury (how much spinal cord tissue is lost upon initial trauma) as well as the location of the injury (whether the injury is more to one side of the spinal cord vs. in the middle):
    Yes, there is the possibility that the only way to re-establish some connections would be direct connection between brain/brainstem neurons and lower motor neurons, in which case the upper neurons would have to grow quite a long distance.
    No, the upper neurons would not have to grow quite as long a distance if they could bridge on to spared propriospinal neurons.

    This is one of those questions that, unfortunately, will never have a simple answer that applies to everyone.


    • #3
      Thanks. I wonder If the umn can remember its path