I don't know where you were looking, but this page https://nora.cc/member-resources/nor...es-on-nor.html has some 700 articles published in peer-reviewed journals. Obviously not all peer-reviewed articles are publishing results of actual experiments, but just searching a few of them (you need access to a university's credentials unfortunately to access most peer-reviewed literature, unless it's open-access) I found many that published actual results related to the subject matter.

Unfortunately large scale clinical trials like that take a lot of money, and there just hasn't been an emphasis on funding research on TBI treatment until relatively recently. I also doubt that every TBI patient that Dr. Zelinsky sees experiences the dramatic improvement that Clark Elliott did. Every concussion/TBI is different, as we hear so much on this site. Depending on the specifics of what's injured, some people probably respond really well to treatment by someone like Dr. Zelinsky, while the nature of others' injuries might be such that it isn't helpful. From a patients perspective, all we can do is try.