An injection into the C1–C2 joint at the very top of the neck, for headache that is genuinely coming from that joint. Performed under fluoroscopy, never blind.
What the atlanto-axial joint has to do with headache
The atlanto-axial joint is the articulation between the first and second cervical vertebrae — the joint that lets you shake your head “no”. It carries far more rotation than any other joint in the neck, and it is a recognised source of cervicogenic headache: pain referred from there is felt in the back of the head and behind the ear, usually on one side.
It is also frequently missed, because it sits above the levels most cervical imaging and most injections address.
Why this one is never done blind
The vertebral artery and the C2 nerve root sit immediately adjacent to the injection target, and the spinal cord is a few millimetres away. This is one of the injections in interventional pain practice where image guidance is not a refinement — it is the difference between a safe procedure and an unacceptable one.
It is performed under fluoroscopy with contrast confirmation: the needle position is verified radiographically, and contrast is injected first to confirm the medication will go where it is intended and not into a vessel.
Diagnostic first
As with other blocks here, the first injection answers a question. If anesthetising the C1–C2 joint abolishes your headache, that joint is the generator, and longer-term options become reasonable. If it does not, the source is elsewhere and we look again.