This is a late complication of all head and neck radiation. My carotids have gone from clear at the beginning, to about 50% occluded now at 10 years out. The issue is not the radiation induced scar tissue occlusion which can make me light headed when I get up from laying down. It IS a problem if he has other risk factors such as high blood lipids, plaques, or calculus in the arteries. These show up on scans differently than scar tissues and certainly different on doppler ultrasounds, so telling this all apart isn't rocket science. Scar tissue is not going to break off and cause any kind of transient ischemic attack or stroke. It is there for the duration. I have had ultrasounds for 6 years in a row and also annual MRI's. No plaques. This issue of not enough blood on occasions to the brain is there, but is this a reason to panic? My cardiologist that has seen lots of H&N patients says no. If it got to the point that it was interfering with my life they could be stented, but he does not recommend that into the foreseeable future. The ER doc you talked to who is not as versed in head and neck radiation patients has this wrong. Unless your husband has had a life of bad diet, lots of fats, and all the things that lead to artery/cardiac illness to begin with, this is not a panic level issue if it is radiation induced. Now you need to evaluate what kind of stenosis exists.

I get light headed when I workout (box) and in some other activities. There is no sudden onset of this except when I get up from a supine position, and I have learned to do that slowly. If he is having any transient vision changes or other things that make you believe he has different risk factors for all this, then he MUST be tested and evaluated fully. I would want someone for whom this was a specialty checking him out, even though dopplers etc. are straightforward to do and read. I would not want an opinion on something that has serious potential to be determined by either an ER room doc (great guys for other things) or a general practice MD. Though from the way you state this some event happened. So a work up is in order to determine cause. While he's at it you might as well see that this evaluation includes a stress test (if he is far enough out of treatment to deal with this) and complete lipid panel, a complete ultrasound of the neck, and if there are other risk factors that show up perhaps even a trans esophageal echo which can see angle to the valves in the heart that external ultrasounds cannot. If he has other risk factors he may need to go on statins and modify other aspects of his life. Carotid stenosis from these lifestyle risk factors is usually not isolated to the carotids.