Unfortunately, stutter is more than just 'physhical handicap', it's a neurological disorder. So the 'injury' is explicit in brain areas. Stutter is one of speech impediments induced from abnormal brain functions although a good mindset is necessary and can migitate or even cure stutter. I'm not expertise at neuropathologic treatments, but I can warrant the future of treatments to stutter must be some treatments that can truly repair the abnormal brain areas like reducing the activities of fasciculus in the inferior temporal gyrus, stimulating the Broca's area or similar stuffs.