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Manual Therapy 12 (2007) 29–33

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Original article

Myofascial trigger points in subjects presenting with mechanical neckpain: A blinded, controlled study

C. Fernandez-de-las-Penas�, C. Alonso-Blanco, J.C. Miangolarra

Department of Physical Therapy, Occupational Therapy, Physical Medicine and Rehabilitation, Universidad Rey Juan Carlos (URJC), Alcorcon, Spain

Received 12 November 2004; received in revised form 4 January 2006; accepted 3 February 2006

Abstract

The aim of this study was to describe the differences in the presence of myofascial trigger points (TrPs) in the upper trapezius,

sternocleidomastoid, levator scapulae and suboccipital muscles between patients presenting with mechanical neck pain and control

healthy subjects. Twenty subjects with mechanical neck pain and 20 matched healthy controls participated in this study. TrPs were

identified, by an assessor blinded to the subjects’ condition, when there was a hypersensible tender spot in a palpable taut band, local

twitch response elicited by the snapping palpation of the taut band, and reproduction of the referred pain typical of each TrP. The

mean number of TrPs present on each neck pain patient was 4.3 (SD: 0.9), of which 2.5 (SD: 1.3) were latent and 1.8 (SD: 0.8) were

active TrPs. Control subjects also exhibited TrPs (mean: 2; SD: 0.8). All were latent TrPs. Differences in the number of TrPs between

both study groups were significant for active TrPs (Po0.001), but not for latent TrPs (P40.5). Moreover, differences in the

distribution of TrPs within the analysed cervical muscles were also significant (Po0.01) for all muscles except for both levator

scapulae. All the examined muscles evoked referred pain patterns contributing to patients’ symptoms. Active TrPs were more

frequent in patients presenting with mechanical neck pain than in healthy subjects.

r 2006 Elsevier Ltd. All rights reserved.

Keywords: Mechanical neck pain; Myofascial trigger points; Myofascial pain; Blinded controlled study

1. Background

Mechanical neck pain affects 45–54% of the generalpopulation at some time during their lives and can resultin severe disability (Cote et al., 1998). The exactpathology of mechanical neck pain is not clearlyunderstood and has been purported to be related tovarious anatomical structures including, uncovertebralor intervertebral joints, neural tissues, discs, musculardisorders and ligaments (Simons et al., 1999; Maitlandet al., 2000). Different authors often assume thatmechanical neck pain is associated with muscular, joint

see front matter r 2006 Elsevier Ltd. All rights reserved.

ath.2006.02.002

ing author. Cesar Fernandez de las Penas, Facultad de

alud, Universidad Rey Juan Carlos, Avenida de Atenas

orcon Madrid, Spain. Tel.: + 34 91 488 88 84;

8 89 57.

resses: cesarfdlp@yahoo.es, cesar.fernandez@urjc.es

-de-las-Penas).

and neural impairments (Simons et al., 1999; Maitlandet al., 2000). Soft tissue therapies and spinal manipula-tion/mobilization are manual therapies commonly usedin the management of mechanical neck pain andassociated impairments (Gross et al., 2002).

Simons et al. (1999) have claimed that myofascialtrigger points (TrPs) from neck and shoulder musclesmight play an important role in the genesis ofmechanical neck pain. There are epidemiological studiessuggesting that TrPs represent an important source ofmusculoskeletal disorder (Chaiamnuay et al., 1998). ATrP is a hyperirritable spot within a palpable taut bandof a skeletal muscle that is painful on compression,stretch or overload of the affected tissues and that cangive rise to a typical referred pain pattern (Simons et al.,1999). TrPs are typically located by the followingphysical examination findings: presence of a palpabletaut band in a skeletal muscle, tender spot within the

ARTICLE IN PRESSC. Fernandez-de-las-Penas et al. / Manual Therapy 12 (2007) 29–3330

taut band, local twitch response provoked by snappingpalpation of the TrP, and referred pain pattern (Simonset al., 1999). The formation of TrPs may result from avariety of factors, such as severe trauma, overuse,mechanical overload or psychological stress (Simonset al., 1999). Recent studies have hypothesized that thepathogenesis of TrPs results from injured or overloadedmuscle fibres. This leads to involuntary shortening, lossof oxygen supply, loss of nutrient supply and increasedmetabolic demand on local tissues (Mense et al., 2000).

Although previous studies have investigated theprevalence of TrPs in benign chronic headaches (Jaeger,1989; Marcus et al., 1999), we were unable to locate anystudy in the peer-reviewed literature analysing theprevalence of TrPs in the cervical musculature (levatorscapulae, sternocleidomastoid, upper trapezius muscle).These TrPs have the potential to refer pain contributingto neck and shoulder symptoms in patients presentingwith mechanical neck pain. Our aim was to describe thedifferences in the presence of TrPs in the uppertrapezius, sternocleidomastoid, levator scapulae andsuboccipital muscles between subjects with mechanicalneck pain and healthy controls. In addition, weexamined the possible correlation in the presence ofTrPs among the aforementioned muscles.

2. Material and methods

2.1. Subjects

Twenty subjects presenting with mechanical neck painfor at least 4 months and 20 healthy age- and sex-matched controls without neck pain during the prior 6months participated in this study from January toSeptember of 2004. For the purpose of this study,mechanical neck pain was defined as generalized neckand/or shoulder pain with mechanical characteristicsincluding: symptoms provoked by maintained neckpostures or by movement, or by palpation of thecervical muscles. Patients were excluded if they exhibitedany of the following: (1) diagnosis of fibromyalgiasyndrome according to the American College ofRheumatology (Wolfe et al., 1990); (2) previous historyof a whiplash injury; (3) history of cervical spinesurgery; (4) diagnosis of cervical radiculopathy ormyelopathy determined by their primary care physician;or (5) therapeutic intervention for myofascialpain within the past month before the study. Thehealth status of all patients was clinically stable,without current symptoms of any other concomitantchronic disease. The clinical history for each patientwas solicited from their primary care physician toassess the exclusion criteria and to check the presenceof ‘‘red flags’’, i.e. infection, malignancy. Subjectswith neck pain were examined on days in which the

neck pain intensity was less than four points on a 10-cmhorizontal visual analogue scale. This study wassupervised by the Department of Physical Therapy,Occupational Therapy, Physical Medicine and Rehabi-litation of the Universidad Rey Juan Carlos. Theresearch project was approved by the local humanresearch committee of the Universidad Rey Juan Carlos.All subjects signed an informed consent prior to theirinclusion.

2.2. Procedure

Subjects were examined for TrPs by an assessor whohad more than 4 years experience in TrPs diagnosis, andwho was blinded to the subjects’ condition. Thediagnosis of the TrP was performed following the latterfive diagnostic criteria described by Simons et al. (1999)and by Gerwin et al. (1997): (1) presence of a palpabletaut band in a skeletal muscle; (2) presence of ahypersensible tender spot in the taut band; (3) localtwitch response elicited by the snapping palpation of thetaut band; (4) reproduction of the typical referred painpattern of the TrP in response to compression; and (5)spontaneous presence of the typical referred painpattern and/or patient recognition of the referred painas familiar. If the first four criteria were satisfied the TrPwas considered to be latent. If all of the aforementionedcriteria were present the TrP was considered to be active(Gerwin et al., 1997; Simons et al., 1999). Tender pointswere also diagnosed when subjects reported localtenderness but they did not report referred pain tocompression and/or overload of the affected tissues, sominimum criteria for TrP diagnosis were not fulfilled(Gerwin et al., 1997; Simons et al., 1999).

In criteria four and five, pressure on the TrP wasassessed using a Pressure Threshold Meter (PTM). Theassessor applied continuous pressure approximately at arate of 1 kg/cm2/seg until 2.5 kg/cm2. A PTM distributedby ‘‘Pain Diagnosis and Rehabilitation’’ commercialhome (233 East Shore Road, Suite 108, Great Neck,New York 11023) was used in this study. The PTMconsists on a rubber disk with 1 cm2 surface The rubberdisk is connected to a pressure pole inserting into agauge which records pressure in kilograms (kg). Pressuremeasurements are expressed in kg/cm2. The range ofpressure is between 0 and 10 kg/cm2 recording valueseach 0.1 kg. Previous papers reported an intra-examiner(I.C.C.) reliability of the PTM ranging from 0.6 to 0.97,and an inter-examiner reliability (I.C.C.) ranging from0.4 to 0.98 (Takala, 1990; Levoska, 1993). Pressurethresholds lower than 3 kg, are considered abnormal(Fischer, 1996). Fig. 1 details the location and thereferred pain patterns evoked by TrPs in the examinedcervical muscles based on the comprehensive researchperformed by Simons et al. (1999).

ARTICLE IN PRESSC. Fernandez-de-las-Penas et al. / Manual Therapy 12 (2007) 29–33 31

2.3. Analysis of data

Descriptive data was collected on all patients. Thenumber of active and latent TrPs was recorded for eachpatient and then the group mean was calculated. Theinter-group comparison between the number of TrPs(active or latent) was analysed with the unpaired t-test.

Fig. 1. Referred pain pattern from myofascial trigger points in some

cervical muscles based on the comprehensive research performed by

Simons et al. (1999).

Table 1

Distribution of subjects with myofascial trigger points (active or latent) in b

Suboccipital muscles Upper trapezius muscle

Left side Right side

Subjects with mechanical neck pain

Active TrPs (n) 10 7 8

Latent TrPs (n) 8 7 5

Control healthy subjects

Active TrPs (n) 0 0 0

Latent TrPs (n) 5 8 10

P-value 0.001 0.01 0.006

TrP, myofascial trigger point; NS, non-significant; n, number of subjects, P-va

TrPs were not significant.

The w2 of association was used to assess the differencesin the distribution of TrPs within each muscle betweenboth study groups and the presence of TrPs among theanalysed cervical muscles. The statistical analysis wasconducted at a 95% confidence level. A P-value lessthan 0.05 were considered as statistically significant.

3. Results

A total of 20 neck pain subjects, 7 men and 13women, 20–44 years old (mean age: 2877 years), werestudied. The duration of neck complaints ranged from 7to 15 months (mean ¼ 9.2573 months). The mean levelof neck pain according to the 10 cm visual analoguescale on the day of the examination was 2.5 cm (SD 0.7).Control subjects were 20 healthy volunteers, 10 men and10 women, aged 20–50 (mean age: 2979 years).

Each of the 20 neck pain patients exhibited at leastthree TrPs in the analyzed muscles. The mean number ofTrPs on each patient was 4.3 (SD: 0.9), of which 2.5(SD: 1.3) were latent and 1.8 (SD: 0.8) were active TrPs.On the other hand, each control subject also exhibitedTrPs (mean: 2; SD: 0.8). All were latent TrPs.Differences in the total number of TrPs (active andlatent) and the number of active TrPs between bothstudy groups reached the statistical significance(Po0.001). Differences in the number of latent TrPswere not significant (P40.05).

Moreover, differences in the distribution of activeTrPs within each cervical muscle were also significantfor all muscles except for both levator scapulae (seeTable 1). Within the neck pain group, TrPs in thesuboccipital muscles were the most prevalent (n ¼ 18;90%), following by TrPs in the right sternocleidomas-toid muscle (n ¼ 17; 85%), and TrPs in the left uppertrapezius muscle (n ¼ 14; 70%). Surprisingly, TrPs inthe suboccipital muscles were the most prevalent in ourneck pain patients (90%). As the referred pain evoked

oth study groups

Levator scapulae muscle Sternocleidomastoid muscle

Left side Right side Left side Right side

0 3 3 5

6 3 10 12

0 0 0 0

6 7 1 4

NS NS 0.001 0.001

lues express differences between active TrPs. Differences between latent

ARTICLE IN PRESSC. Fernandez-de-las-Penas et al. / Manual Therapy 12 (2007) 29–3332

by these TrPs spreads to the head and it is usuallyperceived as headache (Simons et al., 1999), patientswere asked for the presence of headache. Half of thesepatients reported tension-type headache concomitantwith their neck symptoms, especially when their neckpain were aggravated by stress. Within the controlgroup, the most prevalent TrPs were located in bothupper trapezius muscles (n ¼ 10; 50% in the right side;n ¼ 8; 40% in the left side) and in the right levatorscapulae muscle (n ¼ 7; 35%).

Finally, w2 analysis by contingency tables showed asignificant relationship between the presence of TrPs inthe left upper trapezius and left sternocleidomastoidmuscles (P ¼ 0.03), between TrPs in the left uppertrapezius and left levator scapulae muscles (P ¼ 0.005)and between TrPs in the right upper trapezius andsuboccipital muscles (P ¼ 0.05). Other relationships, i.e.TrPs in the right or left sternocleidomastoid andsuboccipital muscles, did not reach a significant level(P ¼ 0.06).

4. Discussion

Our study is the first to provide preliminary evidencesuggesting that active myofascial trigger points (TrPs)are more common in subjects presenting with mechan-ical neck pain than in healthy controls. Active TrPs ofthe examined muscles evoked referred pain patternscontributing to neck symptoms seen in our patients.Simons et al. (1999) claimed that neck pain might beusually provoked by TrPs in the upper trapezius andlevator scapulae muscles. Almost all neck pain patientsshowed TrPs in the upper fibres of the trapezius muscle,in the right and/or left sides. Most of these TrPs wereactive TrPs, as patients were familiar with the location(posterior-lateral region of the neck) and the quality ofthe referred pain (tightening and burning) that waselicited by pressure applied to the TrP. When theassessor applied pressure to that TrP, many patientsreported: ‘‘Yes, this is exactly the pain that I usuallyfeel’’.

On the other hand, active TrPs in the control healthygroup were scarce (Po0.001). TrPs in this group neverevoked a familiar ache, and therefore were classified aslatent TrPs (Gerwin et al., 1997; Simons et al., 1999).Significant differences between neck pain subjects andhealthy controls were found for active TrPs, but notfor latent TrPs. This is expected, as latent TrPs, havebeen commonly observed in healthy, normal subjects(Chaiamnuay et al., 1998).

Hong (1994) claimed that the treatment of ‘‘key’’ TrPsin some muscles could also relieve the pain arising fromsatellite TrPs in other muscles. This was one of thereasons for assessing the possible relationship on thepresence of TrPs in the cervical musculature. Our results

have showed different relationships among the presenceof TrPs in some of the analysed cervical muscles. Onehypothesis to justify these relationships might be thatmuscles located in the region of the referred pain patternof a TrP might also develop secondary TrPs (Hong,1994; Simons et al., 1999). This hypothesis might explainour results: the presence of TrPs in the sternocleido-mastoid was associated to the presence of TrPs in thehomo-lateral upper trapezius muscle, or TrPs in theupper trapezius muscle associated to TrPs in the homo-lateral levator scapulae. However, our study design didnot enable a cause and effect relationship to beestablished so further studies are required on that topic.

TrPs diagnosis needs adequate innate ability, training,and clinical practice to develop a high degree ofreliability in the examination (Gerwin et al., 1997;Sciotti et al., 2001). Moreover, some muscles areconsistently more reliably examined than others. Simonset al. (1999) and Gerwin et al. (1997) recommend thatthe minimum acceptable criteria for active TrP diagnosisis the combination of the presence of a spot tendernessin a palpable taut band in a skeletal muscle and patientrecognition of referred pain that is elicited by pressureapplied to the tender spot. These criteria had obtained agood inter-examiner reliability (k) ranging from 0.84 to0.88 (Gerwin et al., 1997). In the present study, thesetwo minimum criteria identified active TrPs. Further-more, the local twitch response, a confirmatory sign ofTrP diagnosis (Simons et al., 1999), was also aninclusion requirement in the diagnosis of TrPs in allmuscles except in the suboccipital muscles, in which it isdifficult or impossible to elicit a local twitch response bysnapping palpation. Suboccipital muscle TrPs wereexplored bilaterally in order to evoke bilateral referredpain (Simons et al., 1999), and also to avoid thepalpation of TrPs in other cervical posterior muscles.The high incidence of suboccipital muscle TrPs in neckpain patients might be provoked because these musclescould not be explored unilaterally. Tender points werealso diagnosed when subjects did not report referredpain elicited by compression and/or overload of theaffected tissues, so minimum criteria for TrP diagnosiswere not fulfilled (Gerwin et al., 1997; Simons et al.,1999).

In the present study the presence of TrPs in subjectswith mechanical neck pain has been demonstrated.However, it is possible that other tissues might alsocontribute to symptoms associated with mechanicalneck pain. Edgar et al. (1994) reported that decreasedextensibility of the upper quadrant neural structures asassessed by the median nerve tension test was associatedwith decreased length of the upper trapezius muscle.Fernandez-de-las-Penas et al. (2005) have recently founda significant relationship between the presence of TrPs inthe upper trapezius muscle and the presence of inter-vertebral joint dysfunctions at C3 and C4 vertebrae.

ARTICLE IN PRESSC. Fernandez-de-las-Penas et al. / Manual Therapy 12 (2007) 29–33 33

Since the relationship of TrPs to impairments in thearticular or neural systems has not been well established,further research is required.

5. Conclusion

Active TrPs are more frequent in neck pain patientsthan in healthy subjects. The prevalence of latent TrPs issimilar in neck pain patients and healthy subjects. Froma clinical standpoint, the results from the study supportsthe clinical practice of assessing TrPs in the cervicalmusculature as one important element of the clinicalreasoning process performed by physical therapists inpatients with mechanical neck pain.

Acknowledgements

We would like to acknowledge Dr. David Simons forhis kind encouragement and support. We would alsolike to thank to each patients who participated in thestudy.

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