His injury, as I understand it, was as a result of taking the Hepatitis vaccine. Weather and stress can affect the vocal cords, resulting in spasms. You can have tightening of the diaphragm and vocal cords resulting in a strained articulation of words. For some, botulism toxin injections into the vocal cord may relax the vocal cord enough to decrease the strained speech. For some speech therapy helps, or acupuncture. It depends on the individual, their situation and the extent of damage as to what, if anything, will be helpful.