I had an MRI done about 6-7 months after my concussion as none of my headache issues were resolving. Upon receiving the results the doctor highlighted that my brain wasn't exactly 'textbook', but said it could mean almost anything. He said that the changes that showed up on the scan were small vessel ischemic changes in the paranchyma, which is basically a change in the blood flow in the vessels, and that there was vascular damage near the point of impact for my head injury (as was expected.)

The symptoms for me have been the most excruciating headaches I have had in my life so far, and not in the sense of dull or normal type headaches, but incredible imploding, burning, stabbing and lightning bolt type pains with everything in between. Usually PCS type symptoms in the months immediately following my head injury such as the usual ringing in ears, sensory sensitivities, motion/ balance etc, though personally I can tell you the ischemic changes themselves have developed as a result of chemicals affecting the already damaged blood vessels in that particular part of my brain. The first thing to cause me big problems was a antihistamine drug, and the second thing to cause me big problems was a large quantity of fish oil. I believe that the these chemicals/ supplements have affected me so adversely because the blood vessels in my brain were already vulnerable from damage.

As for how it is diagnosed, they just pick it off your MRI scan. You have to get it checked by a neurologist though, and better for a couple to check for the sake of second opinions..