Students and staff from two university campuses in Kirksville, Missouri, were recruited to participate in the present study through e-mails and posted flyers. Participants were included if they had current or frequent thoracic spinal pain during the preceding 3 weeks, were aged 18 to 50 years, and had an identifiable paraspinal region that appeared abnormal to palpation by the examiners. Participants were excluded if they had obvious spinal deformities or pathologic processes or any medical condition that precluded them from fine-wire EMG testing, such as abnormal blood pressure, current prescription anticoagulant, antiplatelet therapy, blood disorders, needle phobia, postural hypotension, skin conditions (eg, sensitivity to adhesives), or syncopal attacks. Participants were excluded if no focal tissue abnormality was detected with palpation.
All participants read an information sheet about the study and signed a consent form before participation. The study was approved by the A.T. Still University's Kirksville College of Osteopathic Medicine Institutional Review Board.
Participants reported their present severity of thoracic pain on a visual analog scale of 0 (no pain) to 10 (most pain experienced). They then removed clothing to expose their back (women wore disposable gowns that opened at the back) and lay prone on an osteopathic manipulative treatment table with their face at the midline face hole. Two researchers (G.F. and C.F. or B.R.) experienced in osteopathic manipulative treatment or osteopathic manipulative therapy both palpated the deep tissues in the thoracic PVG region using deep, short gliding movements of the fingertips. A consensus was reached between both examiners on the site with the most marked tissue texture abnormality (ie, hard, boggy, or ropy deep tissues). Because sites that appear abnormal to palpation tend to be more sensitive to pressure,
19 participants in the current study verbally indicated when a site was tender to pressure, thus reinforcing the examiners' palpatory findings.
When an abnormal-to-palpation (AbP) site was located and agreed upon, the skin at this site was marked by impression with light pressure from the end of a plastic tube. Sites two spinal segments above and below the AbP site were palpated to ensure they were relatively normal to palpation (NP) and reported by the participants as not sensitive to pressure. If any of these sites were considered abnormal, then a different NP site was chosen instead—generally a spinal segment above or below that site. The NP sites were marked with the plastic tube in the same manner as the AbP site. These sites were used for insertion of electrodes.