[ research report ] R ecently, in the physical therapy profession con siderable attention has been devoted to exam ining the effectiveness of spinal manipulation in clinical practice. 9,15,16,24,65 The use of thrust manipulation applied to the thoracic spine has been shown to result in increased range of motion, decreased pain, and improvements in function in subgroups of individuals with mechanical neck and shoulder pain. [13][14][15][16]23,43,62,65 Biomechanical theories to explain the effects of spinal manipulation exist, yet the available data do not sufficiently explain how manipulation results in short-or long-term clinical benefits. 20,34,47,56 Researchers have attempted to identify which combination of clinical signs, symptoms, and other pertinent findings from the examination may predict a favorable response to spinal manipulation. 13,43,57 A validation study of a proposed clinical decision rule to identify patients likely to respond to thoracic manipulation found that subjects with mechanical neck pain improved with T T STUDY DESIGN: Case series.
T T OBJECTIVES:To use blood oxygenation leveldependent functional magnetic resonance imaging (fMRI) to determine if supraspinal activation in response to noxious mechanical stimuli varies preand post-thrust manipulation to the thoracic spine.
T T BACKGROUND:Recent studies have demonstrated the effectiveness of thoracic thrust manipulation in reducing pain and improving function in some individuals with neck and shoulder pain. However, the mechanisms by which manipulation exerts such effects remain largely unexplained. The use of fMRI in the animal model has revealed a decrease in cortical activity in response to noxious stimuli following manual joint mobilization. Supraspinal mediation contributing to hypoalgesia in humans may be triggered following spinal manipulation.
T T METHODS: Ten healthy volunteers (5 women, 5men) between the ages of 23 and 48 years (mean, 31.2 years) were recruited. Subjects underwent fMRI scanning while receiving noxious stimuli applied to the cuticle of the index finger at a rate of 1 Hz for periods of 15 seconds, alternating with periods of 15 seconds without stimuli, for a total duration of 5 minutes. Subjects then received a supine thrust manipulation directed to the midthoracic spine and were immediately returned to the scanner for reimaging with a second delivery of noxious stimuli. An 11-point numeric pain rating scale was administered immediately after the application of noxious stimuli, premanipulation and postmanipulation. Blood oxygenation level-dependent fMRI recorded the cerebral hemodynamic response to the painful stimuli premanipulation and postmanipulation.
T T RESULTS:The data indicated a significant reduction in subjects' perception of pain (P<.01), as well as a reduction in cerebral blood flow as measured by the blood oxygenation level-dependent response following manipulation to areas associated with the pain matrix (P<.05). There was a significant relationship between reduced activation in the insular cortex and d...