Dose Response Effects of Cervical Spinal Manipulative Therapy (SMT) on Pressure Sensitivity of Myofascial Trigger Points
Condition: Trigger Points, Myofascial; Myofascial Trigger Points; Myofascial Pain Syndrome
MeSH terms: Myofascial Pain Syndromes; Fibromyalgia
Study type: Interventional
Phase: Phase 2

Summary: 
      Specific Aim 1:

      To determine if the effect of cervical spinal manipulation on the pressure pain thresholds in
      a myofascial trigger point in the infraspinatus muscle can be enhanced and/or extended after
      a second cervical spine manipulation is given during a single subject visit.

      H1: There will be a statistically significant increase in pressure pain thresholds in the
      myofascial trigger point in the infraspinatus muscle after the second cervical spine
      manipulation, as compared to the first.

      Specific Aim 2:

      To determine if the effect of two cervical spinal manipulations on pressure pain thresholds
      in a myofascial trigger point in the infraspinatus muscle will be present at 48 hours
      follow-up. Data will be collected for descriptive purposes and hypothesis generation.
    

Detailed description: 
      Fibromyalgia syndrome (FMS) is one of the most common manifestations of myofascial pain
      syndromes. The total annual cost of FMS is $2298 per patient in Canada. A Canadian study
      suggests that FMS-related productivity loss costs per year are $10,068 per patient. The
      average cost of health resources in Canada is 30% higher in FMS patients compared to non-FMS
      patients and the prevalence of FMS in Canada is 1.1%, leading to a total of over 340 thousand
      Canadians suffering from FMS. As a result, the annual economic burden of FMS to the Canadian
      healthcare system is more than $425 million.

      Typically, FMS patients have widespread musculoskeletal pain with associated non-specific
      tender points. There is an increase in prevalence in active myofascial trigger points (MTrPs)
      contributing to the widespread musculoskeletal pain associated with FMS patients. MTrPs are
      identified as hyperirritable muscular nodules located within taut bands of skeletal muscle
      and can be classified as latent or active. Studies have shown that active and latent MTrPs
      can play a determinant role in the not yet fully understood pathogenesis of FMS.

      There are many common pathophysiological theories that exist for MTrP formation including
      metabolic, biochemical, motor endplate dysfunction, and the neurogenic phenomenon. MTrPs may
      be initiated by a sensitization within the common neurologic segment of the specific tissue
      containing the MTrP. The physiological changes that occur at the MTrP are secondary to an
      increased responsiveness of the neurons within the central nervous system leading to
      increased nociception and increased perception of pain.

      Currently there are a variety of therapeutic techniques established to treat MTrPs including
      spinal manipulative therapy (SMT). SMT may attenuate the nociceptive component of spinal pain
      and MTrPs. SMT increases pressure pain thresholds (PPTs) leading to mechanical hypoalgesia of
      MTrPs in paraspinal muscles. Preliminary data collected by Srbely et al. has shown that there
      is a significant increase in PPTs in infraspinatus MTrPs after cSMT to the C5-C6 spinal
      segments compared to a sham procedure. The measure of PPT is a method of quantifying a
      patient's perception of pain in a MTrP. PPTs can be defined as the least amount of pressure
      stimulus at which a subject perceives pain upon the application of pressure in the form of
      force.

      The appropriate dosage (frequency of application) of SMT needed to achieve optimal pain
      relief for patients with MTrPs has not been established. Haas et al. performed a pilot
      randomized controlled trial to examine the dose response relationship between SMT and
      cervicogenic headaches. The results showed there is a dose-response relationship, increasing
      the dose of SMT leads to a decreased frequency and intensity of headaches. Additionally, Haas
      and colleagues conducted a pilot study to make a preliminary identification of the number of
      chiropractic manipulations required to decrease chronic low back pain and disability. The
      results showed a positive dose-response relationship between SMT and low back pain.
      Dose-response for MTrPs has yet to be established in the current literature. This preliminary
      work will determine the proper dose-response for cSMT in the treatment of MTrPs in one single
      visit.

      Specific Aim 1:

      To determine if the effect of cervical SMT on the PPT in a MTrP in the infraspinatus muscle
      can be enhanced and/or extended after a 2nd cSMT is given during a single subject visit.

      H1: There will be a statistically significant increase in PPTs in the MTrP in the
      infraspinatus muscle after the second cervical SMT, as compared to the first.

      Specific Aim 2:

      To determine if the effect of two cervical SMTs on PPTs in a MTrP in the infraspinatus muscle
      will be present at 48 hours follow-up. Data will be collected for descriptive purposes and
      hypothesis generation.

      Studies show that manual therapy including SMT, is a cost effective method for treating
      chronic pain and FMS. Currently, treatment protocols are arbitrarily selected based on
      opinion or clinical experience. Providing proper guidelines for MTrP and SMT can increase the
      effectiveness of treatment plans and decrease the financial cost of FMS on patients and the
      healthcare system. For this preliminary work, looking at MTrP mechanism is best done in
      isolation of FMS and therefore subjects without FMS will be used.

      Recruitment Process Subjects will be recruited via convenience sampling from the Canadian
      Memorial Chiropractic College campus and main campus clinic through announcements,
      advertising, educating the student body and clinicians on the specific aims of this
      particular study, by emailing the student body asking for volunteers, and by direct
      recruitment through personal contact

      Subject Screening The research assistant will assess all volunteers for eligibility. The
      demographics of all of the volunteers will be collected including gender, age, height,
      weight, hand dominance, and ethnicity. Demographics will be collected so that this
      information can be compared to subjects that do have MTrPs in the infraspinatus muscle. All
      volunteers meeting the eligibility criteria will be included. Reasons for exclusion will be
      collected. Eligible healthy subjects will move on to a physical examination of the cervical
      spine. The physical assessment will include a cervical range of motion screen, palpation of
      the cervical spine, palpation of the infraspinatus muscle bilaterally, and an upper limb
      neurological examination. Documentation if there was pain on palpation of the infraspinatus
      MTrP occurred, if there was referral to the lateral aspect of the shoulder with or without
      palpation of the infraspinatus MTrP, and if there was a local twitch response in the
      infraspinatus MTrP for baseline information. Documentation if the MTrP is active or latent
      will be performed at baseline and if there is failure of randomization a statistical analysis
      will be performed. If, during the assessment the subject reports pain with cervical range of
      motion, or cervical palpation, the presence of arm pain, decreased motor examination,
      abnormal sensation, or the presence of hyper-reflexia or hypo-reflexia, the examination will
      be terminated and the subject will be excluded from the study. Subjects with a MTrP in the
      infraspinatus muscle will have a baseline PPT measurement performed with an algometer to
      ensure the MTrP meets the inclusion of no more than 35N. Subjects that have no cervical spine
      pain, no arm pain, and no neurological symptoms and a MTrP in the infraspinatus muscle no
      more than 35N will be included in the study.

      Those included in the study will be randomly allocated to two separate groups. A
      predetermined computer generated random allocation sequence will be used to separate
      individuals into two groups, those who receive two rcSMT and those who receive one rcSMT and
      one scSMT. The statistician will hold the randomization scheme. To ensure proper concealment
      the statistician will not be involved in the experiment and the clinician and research
      assistant will not be involved in the randomization scheme. The individual group allocations
      will be printed by the research assistant and placed into blank white opaque numbered
      envelopes. The white opaque envelopes will be numbered 001→ 013 for males and 014→026 for
      females. The research assistant will record the number from the envelope on the subject
      information sheet. The research assistant will give the participant an envelope to give to
      the clinician. The research assistant will be blinded but the clinician will be educated what
      the codes mean. The clinician will open the opaque numbered envelope and discretely look at
      the randomization scheme printed on the white card inside, ensuring that the subject does not
      see the randomization scheme. The card with the randomization scheme on it will then be
      placed back in the opaque numbered envelope. For quality control purposes cavitation of the
      rcSMT and scSMT will be monitored by the clinician, any cavitation in the scSMT will be
      documented and accounted for.

      Compensation The participants will receive compensation totaling $35.00 in the form of two
      Tim Horton's gift cards (one for 10 dollars one for 25 dollars) in recognition of the
      subject's time, parking, and gasoline. Subjects will receive a 5-dollar gift card if they
      volunteer and are found not to have a MTrP in the infraspinatus muscle. A 10-dollar gift card
      will be provided to those that complete the first day of the experiment and 25-dollar gift
      card will be provided to those that follow-up after 48 hours.

      Methods related to both Specific Aims Eligible subjects will be asked to first read an
      information letter and then sign an informed consent form for cSMT after all questions are
      answered prior to the physical examination. The research assistant will then give the
      subjects a gown to change into, all clothes covering the upper thorax, abdomen, and upper
      extremities must be removed including but not limited to earrings, necklaces, bras,
      undershirts, t-shirts, and sweaters. The subjects will be instructed by the research
      assistant to place the gown on with the ties facing the back to facilitate palpation of the
      infraspinatus muscle. Subjects will then be instructed to enter the lab and lie prone on the
      chiropractic table. A black non-toxic marker will be used to indicate the exact location of
      the MTrP in the infraspinatus muscle. The baseline PPT of the infraspinatus muscle will be
      taken with a handheld algometer by the research assistant. For reliability PPT measures will
      be taken 3 consecutive times at each time point. Following the baseline procedures, subjects
      will move into the supine position on the chiropractic table with the head on a drop piece.
      The clinician will be at the end of the chiropractic table where the subject's head will rest
      on the drop headpiece. The clinician will perform either an intervention of two consecutive
      rcSMT or one scSMT followed by one rcSMT on the ipsilateral side of the infraspinatus MTrP.
      Manipulation of the cervical spine will be applied to the C5-C6 segments with a force
      indicated for gapping the joint. After the intervention each subject will be asked to fill
      out a questionnaire to address subject treatment expected bias. The subjects will fill out
      the questionnaire and place it in a sealed numbered envelope and give it to the research
      assistant. Prior to leaving all subjects will be reminded by the research assistant to
      retrain from any musculoskeletal treatments or use of any medications not previously
      prescribed.

      Specific Aim #1

      Two rcSMT Group:

      A rcSMT will be performed contacting the C5-C6 segment. The subject's head will be supported
      by the clinician's forearm. The contact hand of the clinician will contact the C5-C6 spinal
      segment. A thrust maneuver will then be given by the contact hand of the clinician to the
      C5-C6 segment with the supportive hand resting on the zygoma of the subject. A rotational
      inferior drop thrust maneuver will be completed19. Immediately after the first rcSMT the
      subject will turn over on the chiropractic table to lie in the prone position for a
      post-rcSMT PPT measurement with the same algometer performed by the research assistant. This
      post-rcSMT PPT measurement will be taken at 5-minute intervals after the first rcSMT. Once
      the PPT measurement is taken the subject will be asked to rest quietly in the supine position
      with the head resting on the drop headpiece. A second rcSMT will be performed at 30 minutes
      after the first rcSMT. The same invention protocol will be repeated. Successive rcSMT will be
      30 minutes part based on the results from Ross et al. showing that a second cavitation of the
      same joint cannot occur before 20 minutes. Thus, 30 minutes will be used so that another
      cavitation of the C5-C6 segment is possible with a 10-minute buffer to account for any
      possible technical difficulties. The subject will turn over to the prone position for repeat
      PPT measurements at 5-minute intervals post-rcSMT for 30 mins. Once the PPT measurements are
      taken the subject will be free to leave and will be compensated. Once the subject has left
      the treatment area the clinician will mark on the treatment card whether the rcSMT was
      performed with or without cavitation for quality control purposes and place the treatment
      card back in its specified numbered envelope and drop it in a drop box that will be place in
      the treatment area.

      One scSMT + One rcSMT Group A scSMT will be performed with the contact hand of the clinician
      resting lightly on the paraspinal area of the neck of the subject. The subject's head will be
      rotated to 45 degrees and will be supported by the clinician's forearm, which will lie on top
      if the headpiece. A thrust maneuver will then be given by the contact hand of the treating
      clinician to the drop piece with the hand beside the paraspinal musculature simulating a real
      thrust, the supportive hand will be resting on the zygoma of the subject. A inferior drop
      thrust will be applied to the drop piece (no thrust is made by the contact hand on the
      cervical spine) (Figure 3 and 4)19. Immediately after the first scSMT maneuver the subject
      will turn over on the chiropractic table to lie in the prone position for a post-scSMT PPT
      measurement with the same algometer performed by the research assistant. This post-scSMT PPT
      measurement will be taken at 5-minute intervals for 30 minutes after the first scSMT. A rcSMT
      will be performed 30 minutes after the first scSMT. The subject will turn over to the prone
      position for repeat PPT measurements in 5-minute intervals for 30 minutes post-rcSMT. Once
      the PPT measurement is taken the subject will be free to leave the treatment area. Once the
      subject has left the treatment area the clinician will mark on the treatment card weather the
      scSMT was performed adequately without cavitation and whether a cavitation occurred with the
      rcSMT or not and place the treatment card back in its specified numbered envelope and drop it
      in a drop box that will be place in the treatment area.

      Specific Aim #2 All subjects regardless of the group will be required to attend a 48-hour
      follow-up after the intervention. The purpose of the follow-up will be to determine the how
      long the effect of the cSMT will last on PPT measurements taken on the infraspinatus MTrP.
      Subjects will be called for a follow-up reminder by the research assistant 1 day prior to
      follow-up to increase compliance. Subjects will present to the Canadian Memorial Chiropractic
      College and will be greeted by the same research assistant (See Specific Aim #1 methods). The
      permanent black mark will be identified for proper infraspinatus MTrP PPT measurement. A
      permanent black will be used to ensure same MTrP will be measured to set the same scene as 48
      hours prior to follow-up. The research assistant will then take one PPT measurement with a
      handheld algometer on the same MTrP. The subjects will be asked to change back into clothing
      and provided with compensation.

      Blinding and Minimization of Bias This study will be a single-blinded RCT in that the
      subjects, statistician providing the randomization scheme, and the research assistant
      performing the physical examination will all be blinded. The experienced clinician providing
      the rcSMT or scSMT procedure will not be blinded. The experienced clinician will have to know
      which group the subject is in to be able to perform the proper intervention (two rcSMT or one
      scSMT and one rcSMT). The bias in administering the SMT intervention in this study will be
      minimized by employing a validated sham procedure created by Vernon et al. in 2005. The
      subject treatment expected bias will be accounted for by recording patient perceptions of the
      treatment protocol.

      Compliance and Co-intervention For the primary specific aim of this study compliance will not
      be a problem due to the limited time needed for the experiment. Compliance for the secondary
      aim where a 2-day follow-up is required for data collection may be more challenging. However,
      the follow-up will be very short consisting of one PPT measurement with a hand held
      algometer. Thus, the time requirement will be approximately 10 minutes in length. Further,
      subjects involved in the experiment will be students and faculty at the Canadian Memorial
      Chiropractic College the same institution that data collection will occur making the
      follow-up more convenient for subjects. Compliance will be increased by a phone call made by
      the research assistant to the subject one day prior to follow-up for a friendly reminder.
      Also, a gift card will be given out upon study completion to increase subject compliance.
      Co-intervention will be avoided by employing the specified eligibility criteria.
      Co-intervention will be avoided due to the short time span of the experimental maneuver.
      Study participates cannot have had any SMT in the pervious month. This washout period of
      treatment is needed to avoid co-intervention. Subjects will be instructed not to have any
      manual treatment between the experiment and the 48-hour follow-up to avoid co-intervention.
      If treatment of the cervical spine occurs data analysis will be modified to account for this.
      Documentation if treatment occurred between intervention and follow-up will be used to see if
      there is a significant outcome from non-compliance.

      Analysis A 2F repeated measures ANOVA will be performed using STATA version 11 software
      (StataCorp LP, College Station, Texas, USA). The within groups analysis will look at time
      points and the between groups analysis will look at group differences. A Post Hoc analysis
      will be performed. All raw PPT measures will be normalized to baseline to account for subject
      variability. A statistician will be conducting the data analysis with the STATA software.
      Descriptive statistics will be used for the secondary aim of this study.
    

Intervention name(s): cervical spinal manipulative therapy
Intervention type(s): Other
Intervention description(s): A real cervical spine manipulation will be used for the intervention vs a sham cervical spine manipulation. For the rcSMT the subject's head will be supported by the clinician's forearm. The contact hand of the clinician will contact the C5-C6 spinal segment. A thrust maneuver will be given by the contact hand of the clinician with the supportive hand resting on the subject's zygoma. A rotational inferior drop thrust maneuver will be completed. For the scSMT the subject's head will be rotated to 45 degrees and will be supported by the clinician's forearm, which will lie on top if the headpiece. A thrust maneuver will then be given by the contact hand of the treating clinician to the drop piece with the hand beside the paraspinal musculature simulating a real thrust, the supportive hand will be resting on the subject's zygoma. A inferior drop thrust will be applied to the drop piece (no thrust is made by the contact hand on the cervical spine).
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: myofascial pain syndrome; myofascial trigger points; spinal manipulative therapy; algometer; pressure pain thresholds