Sarahliz,
I too don't know much about TBI but I have worked in aquatics for 30 years. My mom was a teacher for the physically handicapped and was instrumental in getting a warm water pool built for her students. The key is the warm water--has to be warm. You might check into finding a facility, private or public, that has a chair lift into the pool. There are also wheelchairs that go into the water. What is nice about the water is that the patient can do more which increases his/her muscle memory. Walking is easier in a pool (floatation devices are used for non walkers) and so are cross body movements of the limbs. I remember a kid who had some sort of MD only in his limbs and he used to come into the pool that I taught at in the early am just so that his muscles would be warmed up and loose all day. I can't say enough about the benefits of water therapy or water classes. Water ex for seniors might be slower and more is speed.

Feel free to pm me if you have any more questions,