Yes, all of the time.  Sometimes they are worse than others.  Mom and sis have AS and they also have this issue.  When it is bad for me, it goes on for a whole day. Sometimes I feel like I am flying in a super fast elevator and then I drop all the way to ground and almost pass out.  When people witness this, they say my eyes cross, like I am having seizure.  I have had MRI and CAT Scans and nothing found. I had one doc tell me I was having panic attacks. Yeah, okay, I wish that life was that simple.

What mom and sis and I have figure out (mom is an RN) is that we have an irritation in the Vagus Nerve that controls all sorts of things including heart beat and blood pressure.  When I feel like this, I have laid down with a blood pressure cuff.  I take my blood pressure during each event.  When I feel like my head is pounding and I flying up the elevator, my blood pressure sky rockets to 160/110  when I feel like I am coming down and going to pass out, my blood pressure plummets to 80/70.

We have deduced that either we have a familial problem with the Vagus Nerve that when it get irritated this happens or that the AS fusion caused inflammation of the Vagus Nerve and then we feel crappy.

Hope this helps!

I also have these spells of vertigo and dizziness! Try an otc drug called meclizine... Sometimes it helps me. From the drugs.com website, "Meclizine (meclazine) may also be prescribed for the management of
vertigo (a spinning sensation or a feeling that the ground is tilted)
caused by certain inner ear problems i.e. Within the vestibular system
which contains sensors that control your balance."
Read more: www.drugs.com

This can be a side effect of NSAIDs. For me, when I took a long-lasting version of indomethacin, when the second hit of medicine kicked in I would almost pass out.