There have been many NIH studies on Prolotherapy, most have all resulted in Conclusions needing further study, excepting Fluoroscopically Guided Cervical Prolotherapy.

Abstract is here.

Full Text is here.

Apparently this has been useful in areas where some of our worse headaches evolve - C2/3, and C5/6 - C2/3 for Occipital Neuralgia problems and C5/6 for those wicked whiplash injuries(most commonly).

As we all know, many of our headaches may result from Neck problems from the injuries we have received, so this may be something worthwhile, but not panacea.

Trigger Point Injections respond differently in different people, everyone is an individual and has their own response, as will be the same with Prolotherapy.

One other thing - No One should be injecting the Upper Cervical Spine without Guided Fluoscopy, in a setting with available emergency care - the vertebral arteries anatomy can be challenging to even the best practitioner, and should not have a needle approaching the skeletal area blindly .