How does ascorbic acid help charcot-marie-tooth?

No evidence of that: Charcot-marie-tooth disease is a hereditary disorder that affects peripheral nerves and causes damage to the covering of the nerve sheath. Symptoms include numbness and weakening of hips, legs and feet. This may worsen and cause numbness, weakness and pain in hands and may lead to claw like hands. There is no known cure. A neurologist can diagnose this disease with tests.

Http://www.ncbi.nlm.: Ascorbic acid has been shown to reduce demyelination and improve muscle function in mice...However, its efficacy is unknown in humans.