Comparing how muscle cells heal with brain cells is inappropriate.

Brain tissue is entire different than muscle and fleshy tissues. Brain cells must repair themselves or die. Any new neuronal cells are slow and few to appear if they ever do. Research suggests they do not replicate after the brain has finished maturing at about 25 years old. The repaired cells then need to remake make thousands of axonal connections in a very slow and haphazard format. These torn axons are the primary cause of PCS symptoms.

Muscle tissue/cells are replaced with new muscle cells on a regular basis even when there is not an injury.