Referred pain areas of active myofascial trigger points in head, neck, and shoulder muscles, in chronic tension type headache.

Abstract

SUMMARY: Our aim was to analyze the differences in the referred pain patterns and size of the areas of those myofascial trigger points (TrPs) involved in chronic tension type headache (CTTH) including a number of muscles not investigated in previous studies. Thirteen right handed women with CTTH (mean age: 38 ± 6 years) were included. TrPs were bilaterally searched in upper trapezius, sternocleidomastoid, splenius capitis, masseter, levator scapulae, superior oblique (extra-ocular), and suboccipital muscles. TrPs were considered active when both local and referred pain evoked by manual palpation reproduced total or partial pattern similar to a headache attack. The size of the referred pain area of TrPs of each muscle was calculated. The mean number of active TrPs within each CTTH patient was 7 (95% CI 6.2-8.0). A greater number (T = 2.79; p = 0.016) of active TrPs was found at the right side (4.2 ± 1.5) when compared to the left side (2.9 ± 1.0). TrPs in the suboccipital muscles were most prevalent (n = 12; 92%), followed by the superior oblique muscle (n =11/n = 9 right/left side), the upper trapezius muscle (n = 11/n = 6) and the masseter muscle (n = 9/n=7). The ANOVA showed significant differences in the size of the referred pain area between muscles (F = 4.7, p = 0.001), but not between sides (F = 1.1; p = 0.3): as determined by a Bonferroni post hoc analysis the referred pain area elicited by levator scapulae TrPs was significantly greater than the area from the sternocleidomastoid (p = 0.02), masseter (p = 0.003) and superior oblique (p = 0.001) muscles. Multiple active TrPs exist in head, neck and shoulder muscles in women with CTTH. The referred pain areas of TrPs located in neck muscles were larger than the referred pain areas of head muscles. Spatial summation of nociceptive inputs from multiple active TrPs may contribute to clinical manifestations of CTTH.

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PAIN DISTRIBUTION
Referred pain areas of active myofascial trigger
points in head, neck, and shoulder muscles, in
chronic tension type headache
Ce ´sar Ferna ´ndez-de-las-Pen ˜as, PT, PhDa,b,c,*, Hong-You Ge, MD, PhDb,
Cristina Alonso-Blanco, PT, MScd, Javier Gonza ´lez-Iglesias, PTe,
Lars Arendt-Nielsen, DMSc, PhDb
aDepartment of Physical Therapy, Occupational Therapy, Physical Medicine and Rehabilitation of Universidad
Rey Juan Carlos, Alcorco ´n, Madrid, Spain
bCenter for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University,
Aalborg, Denmark
cEsthesiology Laboratory of Universidad Rey Juan Carlos, Alcorco ´n, Madrid, Spain
dDepartment of Health Sciences II, Universidad Rey Juan Carlos, Madrid, Spain
eCentro de Fisioterapia Integral, Candas, Asturias, Spain
Received 2 April 2009; received in revised form 27 June 2009; accepted 28 June 2009
KEYWORDS
Tension type headache;
Muscle trigger points;
Referred pain areas
Summary
the areas of those myofascial trigger points (TrPs) involved in chronic tension type headache
(CTTH) including a number of muscles not investigated in previous studies. Thirteen right
handed women with CTTH (mean age: 38 ? 6 years) were included. TrPs were bilaterally
searched in upper trapezius, sternocleidomastoid, splenius capitis, masseter, levator scap-
ulae, superior oblique (extra-ocular), and suboccipital muscles. TrPs were considered active
when both local and referred pain evoked by manual palpation reproduced total or partial
pattern similar to a headache attack. The size of the referred pain area of TrPs of each muscle
was calculated. The mean number of active TrPs within each CTTH patient was 7 (95% CI
6.2e8.0). A greater number (T Z 2.79; p Z 0.016) of active TrPs was found at the right side
(4.2 ? 1.5) when compared to the left side (2.9 ? 1.0). TrPs in the suboccipital muscles
were most prevalent (n Z 12; 92%), followed by the superior oblique muscle (n Z 11/n Z 9
right/left side), the upper trapezius muscle (n Z 11/n Z 6) and the masseter muscle
(n Z 9/n Z 7). The ANOVA showed significant differences in the size of the referred pain area
between muscles (F Z 4.7, p Z 0.001), but not between sides (F Z 1.1; p Z 0.3): as
Our aim was to analyze the differences in the referred pain patterns and size of
* Corresponding author: Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Avenida de Atenas s/n, 28922 Alcorco ´n, Madrid,
Spain. Tel.: þ34 91 488 8884; fax: þ34 91 488 8957.
E-mail address: cesar.fernandez@urjc.es (C. Ferna ´ndez-de-las-Pen ˜as).
1360-8592/$ - see front matter ª 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jbmt.2009.06.008
available at www.sciencedirect.com
journal homepage: www.elsevier.com/jbmt
Journal of Bodywork & Movement Therapies (2010) 14, 391e396

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determined by a Bonferroni post hoc analysis the referred pain area elicited by levator scap-
ulae TrPs was significantly greater than the area from the sternocleidomastoid (p Z 0.02),
masseter (p Z 0.003) and superior oblique (p Z 0.001) muscles. Multiple active TrPs exist in
head, neck and shoulder muscles in women with CTTH. The referred pain areas of TrPs located
in neck muscles were larger than the referred pain areas of head muscles. Spatial summation
of nociceptive inputs from multiple active TrPs may contribute to clinical manifestations of
CTTH.
ª 2009 Elsevier Ltd. All rights reserved.
Introduction
Headache is one of the most prevalent neurological disor-
ders (Bendtsen and Jensen, 2009). Tension-type headache
is the most common form of headache and its chronic form
(chronic tension-type headache: CTTH) is one of the most
neglected (Bendtsen and Jensen, 2006) and is difficult to
treat. It has been reported a prevalence rate of 38.3% for
episodic tension type headache and 2.2% for CTTH
(Schwartz et al., 1998). The prevalence of this headache
has increased over the years (Lyngberg et al., 2005). CTTH
may cause substantial levels of disability, not only to
patients and their relative families, but also to the global
society due to very high prevalence (Stovner et al., 2007).
Although there has been an increasing interest in the
pathogenic mechanisms of CTTH, the real patho-anatomical
mechanisms remain to be fully elucidated (Fumal and
Schoenen, 2008). It seems clear that hyper-excitability of
nociceptive pathway plays an important role in CTTH
(Bendtsen and Schoenen, 2006). It has been recently postu-
latedthatCTTHpain,atleastinpart,maybeassociatedwith
referred pain elicited by trigger points (TrPs) in head, neck
and shoulder muscles (Ferna ´ndez-de-las-Pen ˜as et al.,
2007a). A myofascial TrPs is defined as a hypersensitive spot
within a taut band of a skeletal muscle that elicits a referred
distant pain (Simons et al., 1999). From a clinical point of
view, TrPs may be active or latent. Active TrPs cause symp-
toms and both their local and referred pain evoke a familiar
pain for the patient. In CTTH, active TrPs evoke symptoms
similar to those patients perceive during their headache
attacks.We havedemonstrated that CTTHisassociated with
active TrPs in the suboccipital (Ferna ´ndez-de-las-Pen ˜as
et al., 2006a), upper trapezius (Ferna ´ndez-de-las-Pen ˜as
et al., 2007b), superior oblique (Ferna ´ndez-de-las-Pen ˜as
et al., 2005), sternocleidomastoid (Ferna ´ndez-de-las-Pen ˜as
et al., 2006b), temporalis (Ferna ´ndez-de-las-Pen ˜as et al.,
2007c), and lateral rectus of the eye (Ferna ´ndez-de-
las-Pen ˜as et al., 2009) muscles. Additionally, we also
formulated an updated pain model for CTTH involving both
peripheral sensitization from active muscle TrPs and central
sensitization in which active TrPs located in those muscles
innervated by C1eC3 segments or the trigeminal nerve may
be responsible for peripheral
a continuous afferent barrage into the nucleus caudalis of
thetrigeminalnervesensitizingthecentralnervoussystemin
CTTH (Ferna ´ndez-de-las-Pen ˜as et al., 2007d).
Previous studies in patients with CTTH have shown larger
referred pain areas elicited from TrPs in the upper trape-
zius (Ferna ´ndez-de-las-Pen ˜as et al., 2007b) and the tem-
poralis (Ferna ´ndez-de-las-Pen ˜as et al., 2007c) muscles as
compared to controls. In addition, there are a number of
nociceptionproducing
muscles in which TrPs can refer pain to the head and hence
contribute to CTTH (Figure 1), e.g. masseter, splenius
capitis, levator scapulae (Simons et al., 1999), which have
not been included in recent published studies. Therefore,
the aim of this study was to analyze the differences in the
referred pain patterns and size of the areas of those muscle
TrPs involved in CTTH including a number of muscles not
investigated in previous studies.
Material and methods
Patients
Thirteen women diagnosed with CTTH, aged from 30 to 50
(mean age: 38 ? 6 years) years of age participated in this
study. Patients were recruited from an advertisement in
a local newspaper. All subjects were right-handed. Patients
were interviewed by an experienced clinician to be certain
that they fit the inclusion criteria of the International
Headache Society (IHS) criteria for CTTH (IHS, 2004).
Headache pain features, temporal profile, family history,
and past and current medications were ascertained from
the history. To be included, patients had to describe all the
characteristics typical of this headache: bilateral location,
pressing and tightening pain, mild or moderate intensity
(?6 on a 11-point numerical pain rate scale from 0 to 10)
and no aggravation of headache during physical activity. No
patient reported photophobia, phonophobia, vomiting or
evident nausea during headaches. In addition, patients had
to have headaches for at least 15 days/month. Other
primary headaches were excluded. Each patient fulfilled
the criteria for CTTH, and there was no apparent evidence
of secondary headaches. Medication-overuse headache as
defined by the IHS was also ruled out. Furthermore,
patients completed a headache diary for 4 weeks in order
to substantiate the diagnosis (Phillip et al., 2007).
All patients had received several prophylactic drugs
several years ago, but none of them were taking any
prophylactic drug at the time the study was conducted.
Furthermore, patients who received any non-pharmaco-
logical treatment (physical therapy, relaxation) within
6 months prior to the study were not considered for the
study. Ethical approval of the study was granted by the
Local Ethics Committee (VN 2005-0041). Informed consent
was obtained from all subjects, and all procedures were
conducted according to the Declaration of Helsinki.
Headache characteristics
An 11-point numerical pain rating scale (Jensen et al.,
1999) (NPRS; range: 0 Z no pain, to 10 Z maximum pain)
392 C. Ferna ´ndez-de-las-Pen ˜as et al.

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was used to assess headache intensity. The headache diary
was used to calculate the following variables: (1) headache
intensity, calculated from the mean of the NPRS of the days
with headache; (2) headache frequency, calculated by
dividing the number of days with headache by the number
of analyzed weeks (days/week); and (3) headache dura-
tion, calculated by dividing the sum of the total hours of
headache by the number of days with headache (hours/
day). Patients also drew their headache pattern on an
anatomical map.
Muscle trigger point examination
Patients were asked to avoid any analgesic or muscle
relaxant 48 h prior to the examination, and they were
examined when their headache intensity was less than 4 on
the NPRS. Myofascial TrPs were bilaterally explored in
upper trapezius, splenius capitis, sternocleidomastoid,
masseter, superior oblique, levator scapulae and sub-
occipital muscles by an observer assessor who had more
than 8 years of experience in TrP diagnosis. For the upper
trapezius, sternocleidomastoid, splenius capitis, masseter
and levator scapulae muscles, TrP diagnosis was conducted
following the diagnostic criteria described by Simons et al.
(1999): (1) presence of a palpable taut band within a skel-
etal muscle; (2) presence of a hypersensitive tender spot in
the taut band; (3) local twitch response elicited by snap-
ping palpation of the taut band; and (4) reproduction of the
typical referred pain pattern of the TrP in response to
compression. For suboccipital and superior oblique muscles
we adopted the previous published guidelines (Ferna ´ndez-
de-las-Pen ˜as et al., 2005, 2006a). Briefly, the diagnosis of
suboccipital TrPs was made when there was tenderness in
the suboccipital region, referred pain evoked by main-
tained pressure for 10 s, and increased referred pain with
muscle contraction [extension
(Ferna ´ndez-de-las-Pen ˜as et al., 2006a). For the diagnosis of
superior oblique muscle TrPs, we searched for both local
and referred pain elicited by palpation of the superior-
internal corner of the orbit and increased referred pain
with both contraction [infra-adduction of the eye] and
stretching [supra-abduction of the eye] of the muscle
(Ferna ´ndez-de-las-Pen ˜as et al., 2005). TrPs were consid-
ered active if both the local and the referred pain evoked
by manual palpation reproduced total or partial pattern of
the headache (Simons et al., 1999).
Muscle TrPs were searched in each muscle with a 1-min
interval between two consecutive points.
oftheheadeneck]
After TrP
Figure 1
capitis and temporalis muscle TrPs as described by Simons et al. Reprinted with permission from Simons, D., Travell, J., Simons, L.,
1999. Travell & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual, Vol. 1, second ed. Williams & Wilkins,
Baltimore.
Referred pains from upper trapezius, sternocleidomastoid, suboccipital, splenius capitis, splenius cervicis, semispinalis
Referred pain areas of active TrPs in head, neck, and shoulder muscles, in CTTH393

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examination on each point, patients were asked to draw
the distribution of referred pain (if it was elicited during
examination) on an anatomical map. The referred pain area
of muscle TrPs was calculated with a digitizer (ACECAD
D9000, Taiwan).
Statistical analysis
Data was analyzed with SPSS?version 14.0 (SPSS Inc, Chi-
cago, IL) Results are expressed as mean and 95% confidence
interval in the text. The KolmogoroveSmirnov test showed
a normal distribution of quantitative data (p > 0.05). The
differences in the number of active TrPs between both
sides were assessed with the non-parametric Wilcoxon
Signed-Rank test. The chi square (c2) test was used to
assess the differences in the size of the distribution of
active TrPs within each muscle on each side. A two-way
ANOVA was used to detect the differences in referred pain
area (cm2) between muscles and sides. The Bonferroni test
was conducted as post hoc analysis. The Pearson (r) test
was used for the correlation analysis between referred pain
areas and clinical variables relating to headache (intensity,
frequency, duration, history). The statistical analysis was
conducted at a 95% confidence level. A p value-less than
0.05 was considered statistically significant.
Results
Clinical features of the sample
In this CTTH sample, mean duration of the headache history
was 11.5 years (95% CI 7.2e15.8 years). The mean head-
ache period per day was 7.2 h (95% CI 5.8e8.5 h), the mean
intensity per episode was 4.8 (95% CI 4.4e5.2), and the
number of days per week with headache was 4.5 (95% CI
4.1e5.0 days/week). The day of the examination mean
headache intensity was 2.3 (95% CI 2.0e2.6). Headache
intensity was positively associated with the headache
duration of individual attacks (r Z 0.65; p Z 0.02): the
greater the intensity, the longer the duration of the head-
ache. The mean head pain area reported by the patients
during their attacks was 4.1 cm2(95% CI 2.6e5.6) in the
frontal region, 5.9 (95% CI 4.7e7.2) in the occipital region
(including the posterior part of the neck region), 3.3 (95% CI
2.5e4.1) in the left side of the head, and 2.8 (95% CI 1.9e
3.8) in the right side of the head (Figure 2). No correlation
between head pain areas and pain clinical parameters
(intensity, duration or frequency) were found.
Muscle TrPs in CTTH: number, location
and referred pain areas
The mean number of active TrPs within each CTTH patient
was 7 (95% CI 6.2e8.0). A greater number (T Z 2.79;
p Z 0.016) of active TrPs was found on the right side
(4.2 ? 1.5) when compared to the left side (2.9 ? 1.0).
TrPs in the suboccipital muscles were most prevalent
(n Z 12; 92%), followed by the superior oblique muscle
(n Z 11 [85%]/n Z 9 [69%] right/left side), the upper
trapezius muscle (n Z 11 [85%]/n Z 6 [46%]) and the
masseter muscle (n Z 9 [69%]/n Z 7 [54%]). The distribu-
tion of active muscle TrPs was significantly different
between sides for the upper trapezius (c2Z 4.792;
p Z 0.045),the sternocleidomastoid
p Z 0.045) and the levator scapulae muscles (c2Z 5.406;
p Z 0.0354). In such a way, active TrPs were mostly located
in the right side in both upper trapezius and sternocleido-
mastoid muscles, whereas levator scapulae TrPs were
mostly located in the left side. The distribution of active
TrPs in the analyzed muscles is shown in Table 1, and
referred pain areas of particular muscles in Table 2.
The ANOVA showed significant differences in referred
pain areas between muscles (F Z 4.7, p Z 0.001), but not
between sides (F Z 1.1; p Z 0.3). Based on a Bonferroni
post hoc analysis, the referred pain area elicited from
levator scapulae TrPs was significantly greater than the
referred pain from the sternocleidomastoid (p Z 0.02), the
masseter (p Z 0.003) and the superior oblique (p Z 0.001)
muscles. Referred pain areas of upper trapezius, splenius
capitis, suboccipital, and levator scapulae were not
significantly different (p > 0.3).
(c2Z 4.524;
Discussion
This study showed the existence of multiple active TrPs in
different head, neck and shoulder muscles in patients with
CTTH. Both the local and referred pain elicited by active
TrPs reproduced the headache pattern in all the patients.
The presence of bilateral active TrPs in trigemino-cervical
muscles provides a plausible explanation for the symmet-
rical bilateral distribution of pain observed in patients with
CTTH.
Figure 2
Symptom area of the patients with chronic tension type headache included in the current study.
394 C. Ferna ´ndez-de-las-Pen ˜as et al.

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We found up to seven active muscle TrPs within each
headache patient, supporting the assumption of spatial
summation of TrP activity in CTTH, as we have previously
suggested (Ferna ´ndez-de-las-Pen ˜as et al., 2007a,b,d). Our
results underscore the importance of searching for multiple
active TrPs in different muscles in patients with CTTH. This
finding increases the relevance of multiple TrPs because
active TrPs constitute an important source of peripheral
nociception since higher concentrations of chemical medi-
ators (bradykinin, calcitonin
substance P, and serotonin) may be present in active
muscle TrPs (Shah et al., 2005). This hypothesis would be
related to previous assumptions that peripheral nociception
and sensitization mechanisms would play a crucial role in
the evolution from episodic to chronic tension type head-
ache (Bendtsen and Schoenen, 2006). Therefore, clinicians
should search and treat active muscle TrPs in the muscu-
lature which receives a trigemino-cervical innervation in
patients with CTTH and try to treat those which referred
pain TrP reproduced the headache attack.
We also calculated the referred pain areas elicited by
active TrPs and found that referred pain areas of sub-
occipital and levator scapulae muscle TrPs were the com-
monestones. It is interesting
(suboccipital, levator scapulae or splenius capitis), instead
of head muscles (masseter or superior oblique), showed the
greatest referred pain areas. These findings claim for the
relevance of neck muscles in pain perception in CTTH.
gene-relatedpeptide,
tonotethat neck
Previously we assessed referred pain areas from the upper
trapezius (Ferna ´ndez-de-las-Pen ˜as et al., 2007b) and tem-
poralis (Ferna ´ndez-de-las-Pen ˜as et al., 2007c) muscles, but
not from the remaining muscles included in the current
study. The current study increases the number of muscle
TrPs which referred pain is contributing to headache pain
pattern in CTTH. Additionally, we also showed that the
referred pain areas of the analyzed muscles covered the
extension of the entire headache pain pattern of the
patients, although we should consider that the referred
pain areas of some muscle TrPs, e.g. suboccipital, splenius
capitis, and upper trapezius, are located in the same region
of the head (frontal or lateral side of the head or neck). In
addition, we should take into account that the referred
pain pattern of the levator scapulae muscle did not reach
the head. Nevertheless, since all CTTH patients reported
neck pain symptoms, active TrPs in this muscle are related
to the neck pain pattern present in CTTH. Finally, the
referred pain patterns elicited by active TrPs in the current
study were very similar to those previously reported by
Simons et al. (1999) and by Beat de Jung (2006). Never-
theless, some slight differences may be observed, probably
due to the pathology of the patients included, or due to the
sensitization state in which the patients were explored.
An interesting finding was that active TrPs in the upper
trapezius and sternocleidomastoid muscles were mostly
located in the right side, whereas levator scapulae TrPs
were mostly located in the left side. These results are
Table 1
Number of patients with chronic tension type headache (n) with active trigger points (TrPs) located in each muscle.
Upper trapezius muscleSternocleidomastoid muscle Masseter muscle
Left side Right sideLeft sideRight sideLeft sideRight side
Active TrPs (n)
No TrPs (n)
6
7
1126
7
7
6
9
4211
Splenius capitis muscleLevator scapulae muscle Superior oblique muscle
Left side Right sideLeft side Right sideLeft side Right side
Active TrPs (n)
No TrPs (n)
4
9
4
9
8
5
4
9
9
4
11
2
Table 2
Referred pain areas of active trigger points on each muscles in patients with chronic tension type headache.
Patients with chronic tension type headache
Upper trapeziusRight side (n Z 11)
Left side (n Z 6)
Right side (n Z 6)
Left side (n Z 2)
Right side (n Z 9)
Left side (n Z 7)
Right side (n Z 4)
Left side (n Z 4)
Right side (n Z 4)
Left side (n Z 8)
Right side (n Z 11)
Left side (n Z 9)
n Z 12
3.4 ? 1.2 (2.5e4.2)
2.9 ? 1.2 (1.7e4.2)
2.5 ? 0.7 (1.8e3.2)
1.8 ? 0.4 (1.4e2.6)
2.2 ? 0.5 (1.8e2.6)
2.8 ? 1.0 (1.9e3.8)
3.8 ? 0.5 (3.1e4.6)
3.1 ? 1.5 (1.0e4.4)
4.9 ? 1.1 (3.1e6.6)
4.1 ? 2.0 (2.4e5.8)
2.5 ? 1.1 (1.7e3.2)
2.7 ? 1.6 (1.5e4.0)
4.5 ? 1.3 (3.7e5.4)
Sternocleidomastoid
Masseter
Splenius capitis
Levator scapulae
Superior oblique
Suboccipital
Referred pain areas (cm2) are expressed as means ? standard deviation (95% confidence interval).
Referred pain areas of active TrPs in head, neck, and shoulder muscles, in CTTH395