I was about to go this route with Emma as we were seeing a local Chiro who was "correcting" Emma's upper cervical area, specifically the C1 "atlas" on a fortnightly basis.
I do a lot of reading about Jaw misalingment which lead us to Dr Amir in Putney.
Dr Amir started Jaw correction work on Emma three months ago, her upper cervical and atlas are now perfectly aligned and require no adjustment (they straightened themselves out when the jaw was re aligned).
Before considering Nucca treatment, ask yourself why your neck is out of alignment, maybe (probably) the misalignment of your upper cervical is a symptom of other (jaw) problems.
Take a look at these threads:-chronic-cerebrospinal-venous-insufficiency-ccsvi-f40/topic18706.htmlchronic-cerebrospinal-venous-insufficiency-ccsvi-f40/topic18524.html