This is a difficult question to answer, as there is tremendous variability in outcomes following mild traumatic brain injury and concussion. In general, and if the concussion is managed well, we certainly do not expect any long-term morbidity associated with concussion. In rare cases, we can sometimes see symptoms that do persist, and can range from chronic headaches, fatigue, dizziness, emotional changes, cognitive deficits, sleep disorders, and potentially other associated symptoms. In my experience with athletes, and according to our research, athletes, as a group, will not exhibit long term neurocognitive or symptomatic impairment.
With that being said, we certainly see athletes with protracted recoveries and symptoms, though most of these latter athletes have returned to play too soon after injury, have played through symptoms, and experience recurrent injury as a result. In short, if one is not fully recovered from an initial concussion, less biomechanical force may result in an extension of that injury, and chronic symptoms may potentially emerge in some cases. It should be stated, however, that prospective, longitudinal data is clearly lacking in our field-and more research needs to be done exploring these germane issues.
Regarding treatment, there is exciting work being done in this area. At the the University of Pittsburgh, we are on the verge of conducting research on different treatment regimens with different symptoms clusters and different "subtypes" of concussive injury. We are finding that different medications and therapies may be indicated based upon different symptoms, neurocognitive test profiles, and different risk factors. Also, at the University of Pittsburgh Medical Center, we have now developed a physical rehabilitation protocol that we are using clinically and researching as well. I feel that treatment is next frontier for our field.