Furthermore, after repeated application of manual pressure, local and referred head pain decreased in parallel with decreases in the trigeminal nBR (ie, a decrease in the AUC and increase in latency of the ipsilateral R2 waveform). To our knowledge, this is the first time a manual cervical examination technique has been shown to influence trigeminal nociceptive neurotransmission. Spinal mobilization

is typically applied when dysfunctional areas of the vertebral column are found. Clinicians utilizing manual therapy identify spinal dysfunction based on various features; among these are the ability to reproduce local and referred pain, and restrictions in spinal joint motion.[30, 31] The clinician’s objective in applying manual techniques is to restore normal motion and normalize afferent input from the neuromusculoskeletal high throughput screening assay system.[29] Despite clinical evidence for the benefits of spinal mobilization, the biological mechanisms underlying the effects of spinal mobilization are not known.32-34 One of the principal rationales for manual therapy intervention is that

an ongoing barrage of noxious sensory input from biomechanical spinal dysfunction increases the excitability of neurons or circuits in the spinal cord.35-37 Mechanoreceptors including proprioceptors (muscle spindles, both primary and find more secondary endings and Golgi tendon check details organs), low- and high-threshold mechanoreceptors, high-threshold mechano-nociceptors, and high-threshold polymodal nociceptors[38] within deep paraspinal tissues react to mechanical deformation of these tissues.[39] A significant effect of this “biomechanical remodeling” could be restoration of zygapophyseal joint mobility and joint “play,”[40] precisely the intention of the techniques used in this study. Thus, biomechanical remodeling resulting from mobilization may have physiological ramifications, ultimately reducing nociceptive input from receptive nerve endings in innervated paraspinal tissues.[35, 36, 39] Our findings of decreased AUC and increased

latency of R2 during the cervical intervention are supported by a functional magnetic resonance imaging study in which manual therapy was administered to the ankle joints of rats following capsaicin injection. Subsequent to mobilization, there was decreased activation of the dorsal horn.[41] By analogy, upper cervical afferents may have an excitatory influence on trigeminal circuits in migraine sufferers that can be reduced by reproduction and lessening of usual head pain. The reduction in the nBR during spinal mobilization is consistent with previous studies demonstrating a functional connectivity between the cervical and the trigeminal system in the trigeminocervical complex of the brainstem.