Depending on how badly a nerve is injured will depend on who fast it can recover. If a nerve is cut in half and is sewn together, it can grow at the rate of an inch a month or a millimeter a day. If the nerve is mildly pinched but still functional, then it can recover function in a few hours or it may take a few days. As the nerve compression gets more severe, and if it has been compressed a long time, then it can take months for nerves to improve. Nerve will regenerate better in younger patients than in older patients. But we do see nerve regeneration and functional improvement even in the elderly.