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Is ESWT Effective in the Treatment of Myofascial Pain Syndrome?
Jong-Ick Kim, Hyo-Jin Lee, Hyung-Youl Park, Won-Hee Lee1, Yang-Soo Kim
Department of Orthopedic Surgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, 1Department of Orthopedic Surgery,
Barunsesang Hospital, Seongnam, Korea
Background: Extracorporeal shock wave therapy (ESWT) is one of the treatment options used for patients with myofascial pain syn-
drome (MPS), although its effectiveness is controversial. The purpose of this study was to evaluate the effectiveness of ESWT in the treat-
ment of MPS in terms of pain relief and functional improvements.
Methods: We assessed 93 patients with MPS who underwent ESWT from March 2009 to July 2014. After exclusion of 25 patients with
shoulder diseases, 68 patients were enrolled in the study. The mean follow-up period was 7.5 months (± 4.2 weeks), and the average
duration of symptoms was 5 months (range, 2–16 months). ESWT was applied to intramuscular taut bands and referred pain areas once
a week for 3 weeks. Visual analog scale (VAS) pain scores and American Shoulder and Elbow Surgeons (ASES) scores were obtained at an
initial assessment and at the 6-week, 3-month, and 6-month follow-up assessments.
Results: VAS pain scores and ASES scores improved significantly after 3 sessions of ESWT (p<0.05). Both scores were improved, al-
though not significantly, after 6 weeks (p>0.05).
Conclusions: ESWT is an effective treatment option for patients with MPS.
(Clin Shoulder Elbow 2015;18(4):1-5)
Key Words: Myofascial pain syndromes; Extracorporeal shock wave lithotripsy; Visual analog scale
CiSE
Clinics in Shoulder and Elbow
Copyright © 2015 Korean Shoulder and Elbow Society. All Rights Reserved.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0)
which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
pISSN 2383-8337
eISSN 2288-8721
ORIGINAL ARTICLE
Clinics in Shoulder and Elbow Vol. 18, No. 4, December, 2015
http://dx.doi.org/10.5397/cise.2015.18.4.1
Received May 28, 2015. Revised September 10, 2015. Accepted September 17, 2015.
Correspondence to: Yang-Soo Kim
Department of Orthopedic Surgery, The Catholic University of Korea, Seoul St. Mary’s Hospital , 222 Banpo-daero, Seocho-gu, Seoul 06591, Korea
Tel: +82-2-2258-6117, Fax: +82-2-535-9834, E-mail: kysoos@catholic.ac.kr
Financial support: None. Conflict of interests: None.
Introduction
Myofascial pain syndrome (MPS) is a painful condition arising
from skeletal muscle trigger points.1) Application of manual pres-
sure to these trigger points can induce local and referred pain
consistent with the patient’s symptoms.2) The diagnosis of MPS is
based on several clinical manifestations,3) including tender points
around the levator scapulae, trapezius, and infraspinatus muscle
belly, referred pain to the occipital area and periscapular area,
and palpable intramuscular taut bands.4)
The treatment options for MPS include pharmacological and
non-pharmacological interventions.5) Nonsteroidal anti-inflam-
matory drugs (COX-II inhibitors) and muscle-relaxant agents
(afloqualone, GABAergic drugs) are commonly used for treat-
ment of MPS. Because an intramuscular taut band remaining
after pharmacological treatment may produce continuous pain,
dry needling is occasionally performed to eliminate the band.6)
However, dry needling is an invasive technique. Less invasive
treatments such as extracorporeal shock wave therapy (ESWT)
have recently introduced. Effectiveness of ESWT has been dem-
onstrated in treatment of lateral epicondylitis, calcific tendinitis,
plantar fasciitis, and tendinitis surrounding various joints.7-9)
The purpose of this study was to evaluate the effectiveness of
ESWT in the treatment of MPS in terms of pain relief and func-
tional improvements.
Methods
Ninety-three patients diagnosed with MPS in Seoul St. Mary’s
Hospital from March 2009 to July 2014 were reviewed. Shoul-
der and cervical spine radiographs were examined, and we also
determined whether there were any tender points or palpable
taut bands on the muscles around the scapula and neck. The
presence of paresthesia or local twitch response during ap-
2
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Clinics in Shoulder and Elbow
Vol. 18, No. 4, December, 2015
plication of pressure to certain tender points was included in
the diagnostic criteria. Of these 93 patients, 25 patients were
excluded from the study because of shoulder stiffness, rotator
cuff tears, or calcific tendinitis. Thus, 68 patients (17 men and
51 women) were enrolled in the study. The mean age of the
enrolled patients was 51 years (range, 29–67 years). The mean
follow-up period was 7.5 months (± 4.2 weeks), and the aver-
age duration of symptoms was 5 months (range, 2–16 months).
Some patients had previously undergone several treatments (e.g.,
physical therapy, manual massage, medication, or dry needling);
however none had received treatment within 3 months prior to
presenting to our hospital, and none of the patients had previ-
ously undergone ESWT. Patients had other associated diseases,
such as cervical spine spondylosis. All patients underwent 3 ses-
sions of ESWT during a 3-week period. Follow-up assessments
were performed at 3 months for 52 patients (76.5%) and at 6
months for 35 patients (51.5%) (Fig. 1).
The above-mentioned pharmacological agents were admin-
istered to all patients in conjunction with ESWT treatment. Both
nonsteroidal anti-inflammatory drugs and muscle relaxants were
used, but the type and dosage varied according to the degree of
patient compliance. ESWT was administered as 4,000 impulses
of 0.25 mJ/mm2 at a frequency of 7 Hz using the Swiss Dolor-
Clast (Electro Medical Systems, Nyon, Switzerland). Pressure
was set at 3 bar, and a radial type shock wave was used. After
receiving a diagnosis of MPS, all patients underwent ESWT once
a week for 3 weeks (for a total of 12,000 impulses). One mem-
ber of our shoulder team applied ESWT to the intramuscular
taut band and referred pain area, which mainly included the
trapezius or levator scapula muscles (1–2 tender points). An ad-
ditional session or two was performed in patients who wanted
more than 3 ESWT treatments.
A 10-point visual analog scale (VAS) for pain intensity (where
0=no pain and 10=worst possible pain) was used to measure
each patient’s response to ESWT. VAS pain scores and American
Shoulder and Elbow Surgeons (ASES) scores were checked at
the initial visit and at the 6-week, 3-month, and 6-month follow-
up visits. These scores are widely used at orthopedic clinics for
evaluation of subjective clinical outcomes.
Statistical analyses were performed using SPSS software ver.
12.0 (SPSS Inc., Chicago, IL, USA). The paired t-test was used
for comparison of differences in the functional evaluation scores
before and after treatment. A p-value <0.05 was considered
significant.
Results
Six weeks after ESWT treatment, VAS pain scores had im-
proved in 47 patients, deteriorated in 8 patients, and were
similar in 13 patients. Three months after ESWT treatment, pain
scores had improved in 30 patients, deteriorated in 12 patients,
and were similar in 10 patients. Six months after ESWT treat-
ment, pain scores had improved in 16 patients, deteriorated in
10 patients, and were similar in 9 patients.
A significant improvement in VAS pain scores was observed
after 3 sessions of ESWT (p<0.05) (Table 1). Six weeks after
ESWT, the mean VAS pain score had improved from 4.82
points to 3.28 points. At 3 and 6 months, the mean pain score
Fig. 1. Flowchart showing the study protocol according to Consolidated Stan-
dards of Reporting Trials criteria.
Assessed for eligibility
(n=93)
Excluded (n=25)
Stiffness (n=10)
Rotator cuff tear (n=10)
Calcific tendinitis (n=5)
68 patients enrolled
68 patients followed-up
at6weeks
52 patients followed-up
at3months
Lost to follow-up (n=16)
Lost to follow-up (n=17)
35 patients followed-up
at6months
Table 1. VAS Pain Scores and ADL Scores and ASES Scores Improved aer 3 Sessions of ESWT
Var iab l e
Initial 6 weeks 3 months 6 months
Mean ± SD Mean ± SD p-value Mean ± SD p-value Mean ± SD p-value
VAS 4.82 ± 1.17 3.28 ± 0.72 <0.001 3.17 ± 0.92 <0.001 3.02 ± 0.94 <0.001
ADL 22.80 ± 2.69 26.40 ± 1.83 <0.001 26.20 ± 2.08 <0.001 26.25 ± 2.26 <0.001
ASES 63.85 ± 8.75 77.57 ± 6.38 <0.001 77.80 ± 7.32 <0.001 78.61 ± 6.86 <0.001
Comparison with scores at initial visit and the other visits showedstatistically signicant dierence (p<0.05).
VAS: visual analog scale, ADL: activities of daily life, ASES: American Shoulder and Elbow Surgeons, ESWT: extracorporeal shock wave therapy, SD: standard
deviation.
Extracorporeal Shock Wave Therapy for Myofascial Pain Syndrome
Jong-Ick Kim, et al.
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3
had improved from 4.82 points to 3.17 points and from 4.82
points to 3.02 points, respectively. No significant differences
were found between pain scores measured at 6 weeks and 3
months, 6 weeks and 6 months, and 3 months and 6 months.
After 6 weeks follow-up assessment, mean VAS pain scores had
improved, but not significantly (p>0.05) (Fig. 2).
Activities of daily life (ADL) scores also improved significantly
after 3 sessions of ESWT (p<0.05) (Table 1). Six weeks after
treatment, the mean ADL score had improved from 22.80 points
to 26.40. At 3 and 6 months, mean ADL scores had improved
from 22.80 points to 26.20 points and from 22.80 points to
26.25 points, respectively. No significant differences were found
between scores measured at 6 weeks and 3 months, 6 weeks
and 6 months, and 3 months and 6 months. After 6 weeks fol-
low-up assessment, the mean ADL score had improved, but not
significantly (p>0.05) (Fig. 3).
ASES scores also showed significant improvement after 3 ses-
sions of ESWT (p<0.05) (Table 1). Six weeks after treatment, the
mean ASES score had improved from 63.85 points to 77.57. At
3 and 6 months, mean ASES scores had improved from 63.85
points to 77.80 points and from 63.85 points to 78.61 points, re-
spectively. No significant differences were found between scores
measured at 6 weeks and 3 months, 6 weeks and 6 months, 3
months and 6 months. After 6 weeks follow-up assessment, the
ASES score had improved, but not significantly (p>0.05) (Fig. 4).
VAS pain scores and ADL scores both improved after 3 ses-
sions of ESWT. We conclude that both improvements contrib-
uted to the improvements in the ASES score.
Discussion
The mechanisms of ESWT are unclear, however several
hypotheses have been proposed based on the cellular and
molecular effects of this treatment.10-13) ESWT improves blood
circulation in capillaries, and it reduces the tension and stiff-
ness of muscles, which can interfere with blood flow and cause
excessive stimulation of nociceptors and nerves.14) According to
De Sanctis et al.,15) ESWT improves capillary blood circulation
in chronic ischemic zones. Referred pain in patients with MPS is
due to the ease of inducing central sensitization, because the pe-
ripheral muscle nociceptor threshold is lower than that in other
systems.16) ESWT may interrupt the cascade of referred pain by
inhibiting peripheral muscle nociceptors and reducing levels of
substance P.13) According to Hausdorf et al.,17,18) ESWT reduces
musculoskeletal tissue pain by selectively destroying non-myelin-
ated fibers, and it reduced substance P levels in the dorsal root
Fig. 2. Visual analog scale (VAS) pain scores improved significantly after
extracorporeal shock wave therapy, particularly when initial scores were com-
pared with those for the other visits (6-week, 3-month, and 6-month). *ese
marks mean statistically signicant dierence compared with initial VAS pain
score (p<0.05).
*
Initial 6wk3mo 6mo
10
8
6
4
2
0
**
Visit time
VAS
Fig. 3. Activities of daily life (ADL) scores improved signicantly aer extra-
corporeal shock wave therapy, particularly when compared with initial scores
with the other visits (6-week, 3-month, and 6-month). *ease marks mean
statistically signicant dierence compared with initial ADL score (p<0.05).
*
Initial 6wk3mo 6mo
30
25
20
15
10
5
0
*
*
ADL score
Visit time
Fig. 4. American Shoulder and Elbow Surgeon (ASES) scores improved
signicantly aer extracorporeal shock wave therapy, particularly when com-
paring initial scores with the other visits (6-week, 3-month, and 6-month).
*ese marks mean statistically signicant dierence compared with initial
ASES score (p<0.05).
Initial 6wk3mo 6mo
100
80
60
40
20
0
*
*
*
ASES score
Visit time
4
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Clinics in Shoulder and Elbow
Vol. 18, No. 4, December, 2015
ganglia in an animal study.
The prevalence of MPS is 21% to 85% among individu-
als with regional pain.19) Despite its high prevalence rate, the
pathophysiology of MPS remains unclear. Travell and Simons3)
proposed that damaged muscle fibers become shortened by
calcium reflux into the fibers or by acetylcholine secretion at
the motor endplate. Ji et al.13) hypothesized that MPS originates
from an abnormal increase in the production and release of
acetylcholine, which induces sustained depolarization of the
post-junctional muscle fiber membrane. Released acetylcholine
may cause a continuous release and uptake of calcium ions and
produce muscle ischemia as a result of sustained sarcomere
shortening and the release of sensitizing substances, such as
substance P, bradykinin, calcitonin gene-related peptide, tumor
necrosis factor-α, interleukin (IL)-1B, IL-6, and IL-8. ESWT may
reduce the pain associated with MPS by promoting angiogenesis
and increasing perfusion in ischemic tissues and by altering pain
signaling at the ischemic tissues caused by calcium influx.
Multiple factors can cause muscle pain around the shoulder
and neck. MPS can be caused by poor posture, emotional stress,
obsessive-compulsive disorders, or cervical spine disc disease,
and these problems influence one another.20,21) Therefore, treat-
ing only one of these causes cannot guarantee good results, and
achievement of complete remission can be difficult for patients
with MPS. ESWT softens taut muscular bands, however other
factors such as poor posture or emotional stress cause symptom
recurrence.3) The rapport between the doctor and patient is
important so that treatment can be continued and patients can
be advised about recurrence. A sufficient treatment period and
good patient compliance are also important.
In this study, we investigated the effects of ESWT in the treat-
ment of MPS of the shoulder by evaluating clinical scores. Few
studies have reported a correlation between MPS and shoul-
der scores. In this study, ESWT was applied once a week for
3 weeks. After the treatment period, clinical and pain scores
showed significant improvements. Symptoms and scores were
slightly better at 3 months and 6 months after treatment than
at 6 weeks, although this difference was not statistically signifi-
cant. It is currently unknown how many sessions of ESWT are
required for treatment of MPS, and more studies are required to
establish these guidelines.
The limitations of this study include the small patient group,
the short-term follow-up period, and the absence of a control
group. An additional case-control study using other treatment
options will be necessary, as this was the weakest point of our
study. Because no diagnostic tools have been confirmed for
MPS, our diagnosis mainly depends on the physical examina-
tion. Another limitation of this study is that our patient group
was heterogeneous in nature, but these differences were not ad-
dressed.
Conclusion
VAS pain scores and ASES scores improved after ESWT treat-
ment. ESWT currently represents one of the most effective treat-
ment options for patients with MPS.
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