Suggest Treatment For Dizziness, Nausea And Pressure Headaches
Can wait.
Detailed Answer:
I read your question carefully and I understand your concern.
If I were to judge based on your account I would say that the symptoms are not related to the MRI findings. I believe they are more likely related to the hits you have taken on the head with possible whiplash and post concussion syndrome which may commonly manifest with headache and dizziness, may persist for a few months and needs mainly physical and psychological rest.
Regarding the diagnoses suggested by the MRI, the first two can certainly wait for the appointment. Demyelination means a condition like multiple sclerosis (MS). It is hard to exclude it without viewing images but the use of the term non-specific makes me think they are not in a typical distribution for MS. Also there are no active recent lesion, not responsible for these symptoms, so certainly can wait for appointment anyway.
Gliosis means simply remains from old injuries, sort of like small scars in the brain. Are commonly found, represent remnants from old issues, not an active process, may be due to that old accident you mention.
The last alternative given is vasculitis. It would be a little more worrying and require attention. Can manifest in an insidious way with few symptoms so difficult to exclude it with certainty. However the lack of enhancement, diffusion changes doesn't indicate an active rapidly evolving process, so I would say it can wait till the appointment in a week time.
I remain at your disposal for other questions.