Dry Needling at the Thoracolumbar Junction on Measures of Sympathetic Outflow and Flexibility
Condition: Low Back Pain
MeSH terms: Back Pain; Low Back Pain
Study type: Interventional

Summary: 
      Dry needling (DN) is becoming more frequently performed by physical therapists around the
      world to treat musculoskeletal pain. Dry needling is a form of trigger point therapy that
      evolved from using injections of local anesthetics. Although dry needling is becoming more
      commonly used, there is little agreement on how it works. Researchers have focused their
      efforts investigating other forms of manual therapy until very recently. To date, no studies
      have looked at how dry needling effects muscles distant from the area being treated. Most of
      the body's sympathetic nervous system (fight or flight response) is located in the thoracic
      spine, it may be a "silent" contributor to musculoskeletal problems in the arms and legs. The
      purpose of this study is to determine how dry needling the thoracolumbar junction affects
      pain, flexibility, and other non-invasive measures of nervous system output in people who
      have low back pain and tightness of their hamstring muscles. Standard dry needling treatment
      will be compared with a placebo. The investigators hypothesize that dry needling will have a
      greater sympathetic nervous system response, as measured by changes in heart rate, skin
      temperature and skin conductance, when compared with the placebo. The investigators also
      hypothesize that dry needling will have a greater positive effect on flexibility of the low
      back and hamstring muscles when compared to the placebo.
    

Detailed description: 
      Although DN is being used more often in treatment of musculoskeletal disorders, there
      continues to be little agreement about the pathways on which it works. Research on the
      neurophysiological effects of DN has increased in the past 10 years, however much about the
      treatment is still poorly understood. A better understanding of the neurophysiological
      mechanisms on which DN acts, and how it influences structures distant from the site of
      treatment, can lead to improved choices of therapeutic activities, and potentially superior
      outcomes.

      Many studies have investigated the effects of joint mobilization or manipulation on the
      sympathetic nervous system (SNS), but fewer studies have investigated the effects of DN. Of
      the studies on joint mobilization, a large percentage examined treatment to the cervical
      spine, specifically C5, and tested SNS-related outcomes in the cervical spine, upper thoracic
      spine, and upper extremities (UEs). The sympathetic nerve fibers that supply the lower
      extremities (LEs) originate from T10-L2, and future research should investigate the effects
      on the LE when its direct sympathetic connection is treated.

      At this time, there is minimal research on manual therapy treatment to the thoracolumbar (TL)
      spine and its effect on the LEs. The thoracic spine is the origin of nearly all SNS outflow
      to the extremities, and should therefore not be overlooked as a potentially "silent"
      contributor to musculoskeletal dysfunction in the extremities.

      The goals of this study are:

        1. To quantify the magnitude of the SNS response to DN at the TL junction in subjects with
           low back pain and decreased hamstring length, using valid measures of SNS activity.

        2. To describe the effect of DN at the TL junction on muscle length both local and remote
           to the site of treatment.

        3. To determine if DN to the TL junction has a significantly greater segmental
           sympatho-excitatory effect than extrasegmental effect, as measured by pressure-pain
           threshold (PPT) in the LE and UE.

        4. To determine if immediate changes in SNS activity after DN are related to clinically
           meaningful outcomes at 24-hour follow-up.

      Research questions for this study are:

        1. What are the differences in indicators of SNS activity, such as heart rate variability
           (HRV), electrodermal activity (EDA), skin temperature (ST) and PPT of the LE, when DN or
           sham DN is performed at the TL junction in subjects with low back pain and decreased
           hamstring length?

        2. How does DN to the TL junction affect lumbar paraspinal muscle and hamstring length in
           subjects with low back pain and decreased hamstring length?

        3. How far superiorly does the sympatho-excitatory response ascend when DN is performed at
           the TL junction in subjects with low back pain and decreased hamstring length?

        4. Do immediate changes in SNS activity correlate with greater clinical improvements at
           short-term follow-up, as measured by pain rating, global rating of change (GRC), and the
           Oswestry Disability Index (ODI)?

      Hypotheses for this study are:

      H1: DN will cause a greater SNS response than sham DN, as measured by HRV, ST, EDA, and PPT
      in the LE.

      H2: Subjects who receive DN to the TL junction will have a greater improvement in
      fingertip-to-floor (FTF) measurement, straight leg raise (SLR) and knee extension (KE)
      measurements from baseline than subjects who receive sham DN.

      H3: DN to the TL junction will create a greater sympatho-excitatory effect in the LE when
      compared with the UE, as measured by PPT.

      H4: There is a relationship between immediate changes in sympathetic outflow, as measured by
      low frequency (LF) to high frequency (HF) ratio of HRV immediately following DN or sham DN,
      and GRC, ODI, and pain at 24-hour follow-up.

      A research proposal has been reviewed and approved by the Institutional Review Board (IRB) of
      Nova Southeastern University. Subjects will be recruited via advertisements placed in
      outpatient physical therapy clinics throughout Montgomery and Frederick Counties, in
      Maryland. A power analysis was performed a priori using G Power (Version 3.1.9.3). Sample
      size calculation was based on the primary outcome of SNS activity, and PPT was chosen as the
      primary endpoint because there is the most available data pertaining to PPT after DN
      treatment. Based on the findings for ipsilateral changes in PPT by Salom-Moreno et al when
      compared with a control group, 27 subjects in each group (total 54 subjects) will be required
      to detect an effect size of 0.8 in PPT between the two groups with an alpha level of .05 at a
      power of 0.8. Subjects will be accepted consecutively and data collection will continue until
      the desired number of subjects has been reached.

      Upon arrival at the clinic, the research assistant will confirm that one limb has greater
      than or equal to 15o of hamstring restriction at R1 and R2. If both limbs meet the criteria
      for participation, the most restricted limb will be used for analysis. Subjects will complete
      a Participant Data Form, Informed Consent with assistance from the primary investigator as
      needed, the Numeric Pain Rating Scale (NPRS), and the ODI. The NPRS is frequently used scale
      for quantifying pain. The NPRS is an 11-point scale with anchors of "no pain" and "worst pain
      imaginable." The ODI is one of the most commonly used disability scales for patients with low
      back pain. It has been found as a favorable measure for symptoms ranging from mild to
      severe.20 Excellent test-retest reliability has been proven at 24-hour (r=0.99) and 4-day
      (r=0.91) follow-ups, and test-retest reliability decreases as the length of time before
      follow-up increases.

      Subjects will be randomly assigned to the treatment group or the sham needling group.
      Randomization will occur using a simple method of opaque envelopes sealed with index cards
      indicating the allocated group inside of it. When a subject arrives and is completing the
      initial paper work, an envelope will be selected and opened by the primary researcher. The
      research assistant will be blinded to each subject's group, and will take all baseline
      measurements. These measurements will include PPT, FTF test, KE, and SLR.

      PPT will be measured by a Wagner digital algometer (Wagner Instruments, Greenwich, CT, USA)
      and will be measured in kilograms. Each subject will be instructed to say "stop" when the
      pressure becomes "slightly unpleasant pain." The maximum pressure at the time the subject
      says "stop" will be recorded. The mean of three trials will be recorded.

      The FTF test assesses total trunk flexion mobility and will be performed in the same manner
      as Perret et al in their validity and reliability study. A subject will stand without shoes
      on a 20 cm platform with feet together. While keeping knees, arms, and fingers fully
      extended, the subject will bend forward as far as possible and the vertical distance between
      the tip of the middle finger and the platform will be recorded. The FTF test has been shown
      to have excellent intrarater reliability (ICC=.99). The mean of 3 trials will be used for
      analysis.

      Baseline® digital inclinometers will be used to measure KE and SLR. SLR will be measured in
      supine with the knee fully extended and the ankle in a resting position. The inclinometer
      will be placed at the midpoint between the tibial tuberosity and the distal end of the tibia
      and secured with a Velcro strap. The subjects will be instructed to keep the contralateral
      limb in contact with the treatment table at all times. The contralateral limb and pelvis will
      not be stabilized, as research has shown that stabilization does not affect SLR reliability
      measures. The examiner will record the number of degrees excursion until the first resistance
      is felt (R1), and then the number of degrees at maximum, pain-free elevation (R2). The mean
      of three trials will be recorded.

      KE will be measured in supine similar to Mason et al in their 2016 study. One inclinometer
      will be used to maintain 90o hip flexion, while a second inclinometer will be anchored at the
      midpoint between the tibial tuberosity and the distal end of the tibia. Both will be secured
      with Velcro straps. The subject's lower leg will be passively extended until the first
      resistance is felt (R1) and then at the maximum number of degrees of pain-free knee extension
      (R2).

      After all baseline measurements are completed, subjects will be connected to a BIOPAC® data
      acquisition unit, which will monitor HRV, ST, and EDA. HRV refers to changes in heart rate as
      well as interbeat intervals, and will be used in this study to determine changes in heart
      rate secondary to autonomic nervous system (ANS) activation. HRV will be measured by the
      peak-to-peak intervals when using photoplethysmography (PPG).

      ST is a measure of cutaneous circulation, which is mediated by the sympathetic
      vasoconstrictor and vasodilator nerves. SNS stimulation leads to superficial
      vasoconstriction, which would lead to a decrease in ST. A ST thermistor transducer will be
      taped to the dorsal aspect of the foot of the LE that has the greatest hamstring restriction,
      which will be determine in the baseline testing. Skin thermistor measurements show excellent
      test-retest reliability, with the typical error <0.1 degree Celcius.

      EDA refers to changes in skin conductance when the ANS is stimulated and the sweat glands
      become more active. They are most concentrated in the palms and plantar surfaces of the feet,
      so these would be ideal locations for EDA data collection. It is a sensitive and easy method
      to measure sympathetic arousal, and it is arguably one of the best measures of sympathetic
      arousal because it does not receive input from the parasympathetic nervous system (PNS).
      Electrodes with isotonic gel will be placed on the LE that has the greatest hamstring
      restriction. The active electrode will be on the plantar surface of the foot and the ground
      electrode will be placed on the dorsal surface of the foot.

      An 8-minute acclimation period will occur followed by a 5-minute baseline recording. The
      primary investigator will perform the treatment condition that was randomly assigned. Proper
      clean technique will be followed for all subjects, including the subjects receiving the
      placebo. This will decrease the likelihood that the subject will know which treatment he/she
      is receiving. The PT administering treatment will wear gloves, and 70% isopropyl alcohol will
      be used to prepare the skin over the muscles to be treated.

      Subjects will be treated on the right and left sides at both segments. All materials will be
      handled according to Occupational Safety and Health Administration Blood Borne Pathogens
      standards. Subjects will continue to have SNS output monitored for 5 minutes after treatment
      has been completed. After the 5-minute period, subjects will be disconnected from the
      equipment, and the research assistant will complete all follow-up measurements in the exact
      manner stated earlier in this chapter.

      All subjects will attend one follow-up visit approximately 24 hours after their initial
      visit. The research assistant will gather measurements of FTF, KE, SLR, and PPT of the UE and
      LE. Subjects will also complete an ODI and a GRC during this visit. GRC is a simple and
      convenient scale that is used in research and in the clinic to quantify a summation of a
      patient's improvements in pain, disability, and quality of life. Subjects will be reconnected
      to the BIOPAC® MP36R data acquisition unit as previously described. They will undergo an
      8-minute acclimation period followed by a 5-minute data collection period. The same limb will
      be monitored as in the subject's initial visit. After data collection is complete, subjects
      in the sham DN group will be offered DN in the same manner as the DN group.

      For H1 two-way ANCOVAs will be used for each dependent variable of SNS activity. Covariates
      will include pre-intervention measurement scores and level of needle anxiety. For H2
      flexibility measurements will be separated into "local" and "remote" tests. The FTF test will
      quantify local flexibility, and the SLR and KE tests will quantify remote flexibility. A
      two-way ANCOVA will be use for analysis of local flexibility. The covariate will be the
      pre-intervention scores. For the remote flexibility analysis, a two-way MANCOVA will be used.
      The covariate will be the pre-intervention measurements. Post-hoc testing will be performed
      for H1 and H2 to determine between which factors differences occurred, if applicable. For H3
      the data will be analyzed using a t test. Change scores in PPT in the LE will be compared to
      change scores in the UE, and only the DN group will be included. Prior to conducting the
      tests, data will be analyzed to be sure they meet the assumptions for each statistical test.
      For H4 a Pearson's r will be used to determine if there is a statistically significant
      relationship between SNS output immediately after receiving the treatment condition and the
      outcomes measures of GRC, change in ODI, and change in NPRS. 17 A 2-point change has been
      found to be the minimum clinically important difference in patients with low back pain and
      shoulder pain.
    

Intervention name(s): Dry needling
Intervention type(s): Procedure
Intervention description(s): Using a thin, filiform needle to penetrate a muscle and its trigger point to produce a local twitch response
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Subjects will be randomly assigned to one of two dry needling conditions: dry needling or placebo.
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: low back pain; dry needling; flexibility; sympathetic nervous system