@Blodyn - You have done a good job of arguing your case & presenting images to support your self-diagnosis and taking a stand against having surgery w/ a surgeon who will only “snip the tip” off your styloid & not deal w/ the vascular compression. Good work describing why the external (transcervical) approach is better/necessary in your case!
A digital motion x-ray (DMX) is the type of scan used to diagnose CCI. It is possible the issue with holding your head up for an extended period causing problems is due to nerve/vascular compression as opposed to CCI, however, there’s no way to know for sure unless you have a DMX or an upright MRI, or unless a styloidectomy/IJV decompression on the right produces reduced symptoms. Mr. Hughes does the styloidectomies but w/ the obvious amount your C1 is contributing to the compression, you’d most likely need C1 to also be shaved which would require a second surgery done by Mr. Timothy.
@PatientD has discussed these topics at length in her posts. Here is the link to one where she mentions upright MR in London & Manchester.