This is all about the radiation and not about the dissections. The radiation causes scar tissue to form inside the artery narrowing it. Unlike all the conventional reasons that we have this happen (fatty diets etc.) this is really common in people that have H&N radiation. I too am about 50% occluded and am weighing options. There are issues between coated and uncoated stents and the procedure itself, all of which have risk factors. While it is a common procedure to do in the US in many areas of the vascular system, I personally have put it off in spite of the need and collateral issues, faintness, and more because of the complication rates. Somewhere in my future this is not going to be an option any longer.
Unlike other causes of occlusion/stenosis (to address the original post) opening the artery by other mechanisms where plaques and fatty deposits are the culprit the reasons we get this cannot be addressed by balloon angioplasty and other artery opening procedures. Stents seem to be the main solution.