The reason they performed an Mri of the upper spine and neck relates to (coincidentally but they are not sure) a neck 'injury' I suffered around the same time as the, initial sinus infection that precipitated my balance issues.
I use the inverted commas because this injury, strangely enough came about as a result of using a different pillow and waking up one morning with my head and neck in such an uncomfortable position I could hardly move my Noggin for 10 minutes or so, I have had neck pain ever since.
The Doctor thought this could be a factor in my balance issues.
I did have the other test you described, I remember it well because of the abrasive matter on my forehead.