Hey
@Penelope33: A MRI or CT scan usually is part of the diagnostic process with the initial onset of tinnitus. The scan checks for physical abnormalities, like tumors or lesions, that might be leading to your tinnitus. I am surprised your ENT didn't order it, along with the hearing and tymp tests.
Most tinnitus is not caused by physical abnormalities but you want to make sure -- especially since these are things that perhaps could be fixed through surgery.
Since you already have had the hearing and tymphanic tests, the only other one besides the brain/auditory systems scan I can think of is a VGN, or Videonystagmography, test. It is looking for balance irregularities, dizziness, symptoms associated with Meniere's disease or vestibular problems. I had both a CT and a VGN, as well as the hearing and tymp tests. All of them came back "normal" (well, the VGN test showed my nervous system was hardwired toward vestibular issues, but I have known that for years. Chronic motion sickness, etc).
In the end, all the tests in the world may never show exactly how you got your tinnitus. Many patients never know.
This is just my opinion: But I think at some point, it is helpful to move on from focusing on what caused your T (as long as you have had all the suggested tests to rule out likely causes) to learning how to best manage it.
Hope this helps and good luck.