Pain is a subjective perception, and highly susceptible to placebo effects. This has limited prior research studies fromidentifying differences between verum and sham acupuncture. Objective, physiological outcomes are less susceptible toplacebo effects and we designed our longitudinal neuroimaging studies to evaluate acupuncture mechanisms for a chronicpain disorder characterized by accepted, validated outcomes. Carpal tunnel syndrome is the most common entrapmentneuropathy, affecting the median nerve at the wrist and leading to pain and paresthesia in the hand. Patients were enrolledand randomized into three intervention arms: (i) verum electro-acupuncture ‘local’ to the more affected hand; (ii) verumelectro-acupuncture at ’distal’ body sites, near the ankle contralesional to the more affected hand; and (iii) local shamelectro-acupuncture using non-penetrating placebo needles. Acupuncture therapy was provided for 8 weeks. Nerve conduction studies assessing median nerve sensory latency and brain imaging data were acquired at baseline and followingtherapy. Functional magnetic resonance imaging assessed somatotopy in the primary somatosensory cortex using stimulation over multiple digits. While all three acupuncture interventions reduced symptom severity, verum acupuncture wassuperior to sham in producing improvements in neurophysiological outcomes, both local to the wrist (i.e. nerve conductionlatency) and in the brain (i.e. digit 2/3 cortical separation distance). Acupuncture at local versus distal sites may improvemedian nerve function at the wrist by somatotopically distinct neuroplasticity in the primary somatosensory cortexfollowing therapy. Our study corroborates our prior pilot studies and further suggests that improvements in primary somatosensory cortex somatotopy can predict long-term clinical outcomes for carpal tunnel syndrome. Finding objectiveoutcomes for different chronic pain syndromes may help acupuncture research address the common concerns withdifferentiating acupuncture from placebo, as well as determine acupuncture-specific mechanisms of action.
展开▼
