In a study led by Vernon, H. in 1990, Pressure Pain Threshold Evaluation of the effect of Spinal Manipulation in the Treatment of Chronic Neck Pain: A Pilot Study, published in Journal of Manipulative and Physiological Therapeutics (vol 13, no. 1:13-16) he showed pain was decreased and range of motion increased after limited care. Verhoef, M. did a follow up study in 1997, The Chiropractic Outcome Study: Pain, Functional Ability and Satisfaction with Care, published in Journal of Manipulative and Physiological Therapeutics (vol 20, no. 4:235-240) which showed "patients suffering from back and/or neck complaints experienced chiropractic care as an effective means of resolving or ameliorating pain and functional impairments".