Primary and secondary measures of headache were reduced from baseline for TTH subjects receiving a six-week course of 12 massage sessions that focused on myofascial trigger point therapy and was administered by highly trained therapists. Headache-free days increased by an average of 1 day per week during the second massage phase and 1.5 days per week during the follow-up phase. Furthermore, a 30% decrease in the peak intensity and a 1.2 hour decrease (to 2.8 hours) in the duration of each successive headache incidence was observed. Significant group effects were not apparent until the second three week period of massage therapy. Concomitant with a reduction in headache measures was a decrease in headache-specific disability as measured by the HDI. Importantly, short-term changes associated with massage persisted beyond the massage treatment period as both primary and secondary headache measures during the follow-up period were significantly lower than baseline and were comparable to the second massage period.
Pericranial muscle tenderness is greater in TTH than control or migraineurs and provides an association between peripheral tissues and headache pain28,29
. Muscle tenderness remains apparent even during a headache-free period28,30
. More recently, Fernandez-de-las-Penas et al have drawn attention to myofascial trigger points (MTrPs) in skeletal muscle as sites of interest in TTH31,32
. An active MTrP is a tightly contracted region within a muscle that elicits pain locally (point tenderness) as well as at characteristic distant sites (referred pain), the latter of which can mimic the pain syndrome of the patient33
. Therefore, the MTrP is of particular interest due to its association with local muscle tenderness and its ability to refer pain that mimics the patient complaint, thus providing a peripheral site(s) directly linked with the headache. A focus in this massage study was on reducing active MTrP activity in cervical and cranial muscles, which has been shown to be of higher presence in the upper trapezius and suboccipital muscles of TTH than control subjects11,34
. The value of treating MTrPs of the muscles addressed in the present study is underscored by a recent review article, which concludes that MTrPs are a causative factor for tension-type headache and play a role in the progression from episodic to chronic headache forms35
Multiple methods aimed at reducing MTrP activity have been previously investigated, with mechanical pressure from manual (massage) techniques commonly cited36,37,38,39
. Specific to massage at the MTrP is a study conducted by Gam et al40
who report a significant decrease in the number of MTrPs in the neck and shoulders after a massage and exercise program; the addition of ultrasound to the treatment regimen did not improve results. Furthermore, manual compression applied to myofascial trigger points increases pain threshold and tolerance at the MTrP23,41
. The majority of the specific massage treatment used in this study was directed at reducing active MTrPs in musculature that refer pain to the head region. Although physiological measures of the MTrP were not taken during this study, the therapists reported that MTrPs became increasingly difficult to locate and required greater pressure to elicit referred pain phenomenon following repeated massage visits, factors that suggest a reduction in its metabolic activity.
The mechanism by which a MTrP elicits pain has not been clearly identified. Shah et al found an elevation in chemicals associated with nociception such as bradykinin, substance P, and reduced pH at an active MTrP, but not a latent MTrP or healthy muscle tissue42
. The presence of bradykinin in the MTrP may be an important component in the referred pain phenomenon as injection of a cocktail containing bradykinin into the tibialis anterior resulted in referred pain sensation43,44
. In this regard, massage may mechanically force the muscle fiber sarcomeres at the MTrP nodule apart, thus reducing ischemia and allowing blood flow to the region, which may flush pain-inducing chemicals and allow for tissue recovery to occur36
. Persistent nociceptive stimulation of the central nervous system from the periphery has been argued as a means of progression from episodic to chronic TTH11,45
. Therefore, both peripheral and central mechanisms may be involved with the etiology of TTH46
, which may explain some variability in the effectiveness of massage. It may be necessary to independently address both peripheral and central mechanisms to alleviate persistent tension-type headache pain.
Verbal reports from the participants strongly support a positive effect from massage on headache pain. However, the reduction, but not complete abrogation, of headache pain by massage prompts inquiry into whether a longer duration massage (e.g. 60 minute), additional massage sessions, or a less standardized massage protocol that is tailored to each specific patient would result in a greater effect. Continued improvement in headache measures across the study timeframe suggests that the effectiveness of massage was not exhausted within six weeks, thus additional massage treatments may be beneficial. It is also important to recognize that behavioral changes by the patient such as postural or nutritional adjustments, stress reduction, or breathing mechanics may be necessary to prevent reactivation of a MTrP that can perpetuate headache. Although 12 participants in this study had received professional massage in the 6 months prior to study enrollment, it is unlikely that this experience had a direct effect on treatment outcome. These massages were not headache treatment oriented and all massage was prohibited during baseline data collection. Furthermore, we did not observe significant group effects until after 3 weeks of massage treatment (6 massages), which would argue against prior treatments impacting the study findings.
It is interesting to note that headache instances increased in the week immediately following massage onset, but also continued to decrease for a period following massage cessation. Isometric muscle contraction associated with the myofascial trigger point release technique can result in over-stimulation of a MTrP and perpetuate referred pain and headache phenomenon33
. The initial week of massage denotes a period where the subject becomes acquainted with the therapist and myofascial trigger point therapy techniques; subjects may be unaccustomed to pressure and appropriate sensation for optimizing this type of treatment. The first week following the massage phases may allow a recovery of the MTrPs without additional stimulation from massage, thus allowing residual pain to subside.
While statistically significant, reductions in total as well as the functional and emotional subscales for the Headache Disability Index were found. This finding should be interpreted with caution since a decrease of 19.1 units was noted in this study, yet a 29 point change has been reported as necessary for clinical change27
. The relatively large change necessary for clinical significance limits the robustness of the test as subjects initially reporting moderate disability scores must virtually eliminate associated disability and those with scores below this value are limited by a basement effect20
The comparison to a baseline standard and not a placebo control group limits the ability to assess causality of the treatment. However, selection of participants experiencing TTH for a median of 7.5 years and a 3-week baseline period argues against day-to-day fluctuations causing the observed effects. While a 4-week baseline period is optimal to avoid any fluctuations in headache due to menstrual cycles20
, two-week periods have been argued as satisfactory for TTH research studies47
. Potentially confounding treatments such as an exercise program, physical therapy, or chiropractic adjustments that are often co-administered with massage were not permitted in this study, thus isolating the massage treatment. Our study also employed massage therapists with extensive experience in the field and a specifically designed protocol was followed during each session. This degree of attention to the massage aspect of a treatment regimen for TTH has been insufficiently addressed in previous studies. It is hoped that this initial foray provides impetus for additional research into massage for chronic pain conditions such as TTH.