The purpose of this study is to explore the use of a novel 'microdialysis/acupuncture' needle, designed, fabricated, and tested by the investigators, to determine if this device and technique can successfully sample the chemical milieu of the soft tissue. Specifically, it will be used to measure and compare the quantity of small substances (electrolytes, muscle metabolites, inflammatory mediators, neurotransmitters, cytokines, and arachidonic acid derivatives) in three groups of subjects using a standardized anatomical location (trigger point 1) of the upper trapezius muscle, an area that is recognized as the most common location of myofascial trigger points (MTrPs) in that muscle. These substances are believed to play a critical role in the biochemistry and pathophysiology of soft tissue pain. Subjects will be drawn from a range of ages and both sexes. Trigger point 1is selected specifically to standardize the location of a sampling point in three carefully selected groups: 1) healthy subjects without neck pain who have no MTrPs identified by palpation bilaterally in triggr point 1(no pathological process, no symptoms) 2) healthy subjects without neck pain in whom latent MTrPs are identified by palpation in trigger point 1 in one of the upper trapezius muscles (pathological process, no symptoms) 3) healthy subjects complaining of neck pain of less than 3 months duration with active MTrPs identified by palpation in trigger point 1 in one of the upper trapezius muscles (pathological process with symptoms) This is not a treatment study. Rather, the primary goal of this study is to learn whether this device and technique can successfully sample the chemical milieu in healthy subjects who 1) have pain and those who don't 2) have MTrPs and those who don?t and 3) have active MTrPs versus those who have latent MTrPs. Description of protocol progress: We have thus far recruited 18 subjects (8 women and 10 men), ranging in age from 23 to 66 years old. With our microanalytical sampling technique, we have successfully collected samples at trigger point 1 in the upper trapezius muscle from each subject without any untoward events. We have successfully measured 8 of the 21 analytes in 9 (with 3 in each group) subjects, demonstrating that this technique is able to recover extremely small quantities (<0.5 microliters) of very small substances (<100 kilodaltons molecular weight) directly from soft tissue.

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Intramural Research (Z01)
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Sikdar, Siddhartha; Shah, Jay P; Gebreab, Tadesse et al. (2009) Novel applications of ultrasound technology to visualize and characterize myofascial trigger points and surrounding soft tissue. Arch Phys Med Rehabil 90:1829-38
Shah, Jay P; Phillips, Terry M; Danoff, Jerome V et al. (2005) An in vivo microanalytical technique for measuring the local biochemical milieu of human skeletal muscle. J Appl Physiol 99:1977-84
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