Lots of studies have been done on manipulation for neck pain. Researchers would like to know what works and why. So far they haven't been able to show that a single session gives short-term pain relief. Manipulation combined with heat isn't any better.
A recent study reports on the findings of 33 other studies done using manipulation for neck pain. Treatment was given anywhere from six to 20 sessions. Length of treatment ranged from three weeks to 11 weeks. The results were compared to patients receiving other treatment during the same time frame. No difference in results was found between the groups.
Studies comparing one type of manipulation to another show no difference in results. The best results come when manipulation is combined with exercise. Your improvement may be due to factors other than the chiropractic treatment.