Effects of Dry Needling Technique Into Trigger Points of the Sternocleidomastoid Muscle in Migraine Headache

A Randomized Controlled Trial

Abstract

Objective 

The study aimed to investigate the effect of dry needling into trigger points of the sternocleidomastoid muscle in migraine headache patients.

Design 

Forty subjects with a migraine headache, originating from myofacial trigger points into the sternocleidomastoid muscle (20 subjects in dry needling group and 20 subjects in control group) volunteered to participate in this study. The subjects in the treatment group received three sessions of dry needling in the myofascial trigger point region. Headache frequency, headache intensity, headache duration, drug consumption, muscle thickness, pressure pain threshold, and cervical range of motion were assessed before, immediately after intervention, and at 1-mo follow-up period. In addition, this article was extracted from Iranian Register of Clinical Trials Number IRCT20171219037956N1.

Results 

The experimental group showed significant reduction in the headache parameters immediately after the intervention and at 1-mo follow-up, as compared with the control group. The pressure pain threshold of sternocleidomastoid muscle, cervical range of motion, and muscle thickness significantly increased in the dry needling group in comparison with the control group (P < 0.001).

Conclusions 

The application of dry needling technique caused an improvement in symptoms of migraine patients. Therefore, this technique may be prescribed for treating migraine patients with myofacial trigger points in the sternocleidomastoid muscle.

What Is Known

• Previous studies had investigated manual therapies in migraine patients including joint interventions, massage, ischemic pressure, stretch, or exercise.
• The effect of dry needling (DN) and physiotherapeutic modalities in the treatment of trigger points of the sternocleidomastoid muscle in different patients have been discussed.

What Is New

• The application of DN method caused significant improvement in symptoms of migraine patients.
• The high prevalence of pericranial sensitization and trigger points of neck muscles suggested that DN may relieve pain in these patients.

Headaches are one of most frequent health complaints among adolescents. The World Health Organization reported at least 47% of adults experienced headaches.¹ The International Headache Society divided headache into primary and secondary. Primary headaches include migraine headache, tension-type headache, and trigeminal-autonomic headaches. Migraine headache is prominent because of its wide prevalence and its related problems including pain, disability, and economic impact.² The origin of migraine headache is potentially multifactorial; the vascular, central nervous system, peripheral contributions,³ and nociceptive inputs of myofascial origin⁴ have been identified. Myofascial trigger points (MTrPs) in the craniocervical may stimulate the patient’s symptoms and facilitate migraine pain expression.⁵ Specifically, it has been suggested the MTrPs and painful tension in the upper trapezius (UT), sternocleidomastoid (SCM), and suboccipital muscles as contributory.⁶ The prevalence of these trigger points may be due to postural abnormalities or due to the migraine headache disorder.⁷ Nociceptive inputs of MTrPs might be an initiating or perpetuating factor for migraine headaches. They might potentially contribute to certain craniocervical symptoms found in the migraine subjects.⁴ Inactivation of these trigger points through dry needling (DN) technique may increase the pressure pain threshold (PPT), and cervical range of motion (CROM) and reduce frequency, intensity, and duration of headaches.⁸ Patients with migraine headache often have impairments in the neck neuromuscular function, more trigger points in the cervical musculature, forward head posture, reduced CROM, and increased sensitivity on the cervical muscles.⁴

There are different treatment options for patients experiencing migraine headache, including drug therapy and nondrug therapy interventions. Because of adverse effects in usage of drug treatments, many therapists use physiotherapy techniques in the migraine headache.⁹ These approaches often focus on musculoskeletal disorders, such as spinal manipulation, massage therapy, relaxation technique, posture correction, exercise therapy, stretching of neck muscle, etc.^10,11

More recently, there is a tendency of using DN to treat the trigger points. In the DN, a needle is used to deactivate the trigger point. It is an invasive procedure where the needle is inserted through the skin and muscle into the MTrP. However, its clinical effectiveness is not clear because of lack of objective measures for pain and trigger point status.¹² Therefore, there is a need to develop an objective and reliable measures for assessing the effect of DN therapy on tissue morphologic characteristics with MTrPs that correspond with physical findings and pain.¹³ Hence, there are various methods to evaluate characteristics and morphologies of muscles including electromyography,¹⁴ magnetic resonance imaging,¹⁵ and ultrasonography (US).¹⁶ Evidence has revealed that the US seems to be a more reliable and valid method for studying the function of neck muscles than other methods.¹⁷ Diagnostic ultrasound is used to measure architectural characteristics of muscles, such as thickness, width, and cross-sectional area. Thus, physiotherapists can be used it for physical examination and evaluation of the treatment outcomes.¹⁸

Although the relation between MTrPs and migraine headache is clear,^4,7 no studies have evaluated the effect of DN on the treatment of MTrPs in the SCM muscle of migraine patients. Hence, we hypothesized that the deactivation of trigger points of SCM muscle through DN technique may cause significant improvement of symptoms in the migraine patients. Therefore, this study aimed to investigate the effects of the DN on subjective measurements like frequency, intensity, and duration of headache, drug consumption, PPT, and objective measurement like muscle thickness and active CROM compared with placebo control in the migraine subjects with trigger points in the SCM muscle.

METHODS

This study was a randomized controlled trial done at the research center of the Shiraz University of Medical Sciences in Iran from April to September 2018. Forty patients aged 25–55 yrs diagnosed with migraine headache participated in this study, considering the Consolidated Standards of Reporting Trials (CONSORT) statement guidelines. They were referred to a neurology clinic in the hospital of the Shiraz University of Medical Sciences, Iran, that was invited to participate in this study (Fig. 1).

FIGURE 1: CONSORT flow diagram of the study.

Participants were included if they presented a diagnosis of migraine headache according to International Headache Society criteria as evaluated by a neurologist. Furthermore, participants showed active TrPs in their SCM muscle reproducing their headache and symptoms. The presence of active trigger points was identified if (1) “there was an area of muscle tenderness that was activated by pressure and that, when stimulated, referred pain reproducing the patient’s headache” and (2) “there was a jump sign that was the characteristic behavioral response to compression on a trigger point.”¹⁹

Participants were excluded if they had a history of neck trauma; cervical radiculopathy; previous surgery in the cervical or shoulder area; diagnosed other headaches and unusual migraine; physiotherapy in the cervical area within the previous 6 mos; evidence of needle phobia; or pregnancy.

To determine the sample size, a pilot study was first performed on 10 migraine patients; the results were then used in the software PASS 11 to calculate the sample size with a test type I error 0.05 and test type II error 0.20. According to the statistical formula, it was estimated that 20 subjects in each group were required.

Study Protocol

In this randomized, controlled trial study, block randomization was performed by a statistical expert using excel software. Hence, the participants were randomly divided into the treatment and the control groups. The patients were asked to complete a daily headache diary for 2 wks (baseline phase). At the end of the baseline phase, PPT, CROM, and muscle thickness were evaluated in both groups. Then, the treatment was performed for 1 wk, involving 3 sessions at intervals of 48 hrs. At the end of the treatment phase, the patients completed daily headache diary and the subjects of both groups were assessed again for other variants. The assessment of the variants was repeated at the end of 1-mo follow-up.

All subjects signed an informed consent form approved by the ethics committee of the Social Welfare and Rehabilitation Sciences (Ethics Code Number: IR.USWR.REC.1395.192). Furthermore, this article was extracted from Iranian Register of Clinical Trials Number IRCT20171219037956N1. This study conformed to all CONSORT guidelines and reported the required information accordingly (see Supplemental Checklist, Supplemental Digital Content 1, https://links.lww.com/PHM/B35).

Therapy Group (Dr. Needling)

To apply DN, the patient was requested to be in the supine position. The participant’s neck was placed in slight lateral flexion to the ipsilateral side, to facilitate muscle grip, and the therapist identified the active TrPs within the muscle.²⁰ With the aid of insertion tubes, the standard single-use sterile acupuncture needles (0.25 × 25 mm) were used, following the procedure described by Simons et al.²¹ Both the heads of clavicular and sterna were needled by pincer palpation immediately after identifying the carotid artery. The needle was carried out in an anterior-posterior direction to separate the muscle belly from the neurovascular structures.²² Between 8 and 10 quick needle insertions were inserted deeply into the skin over the trigger points, using a procedure similar to that performed by Hong et al. (1994).²³ Immediately after removing the needle, compression was applied for 90 secs at the needling site with a cotton swab to reduce the intensity and duration of pain. It was applied for three sessions at intervals of 48 hrs (Fig. 2).²²

FIGURE 2: Dry needling procedure of SCM muscle.

Control Group (Placebo)

After active trigger points were determined and the skin was cleaned with an appropriate antiseptic solution, the blunted needle for placebo DN (which causes a pricking sensation) was applied to the trigger points without penetrating the skin after application of a certain pressure to the skin with the insertion tube.²⁴ The protocol was applied three times in 1 wk with at least 2-day break between treatments. Similar to the intervention group, measurement of variables was performed immediately after the treatment and after 1 mo of follow-up.

Blinding

The physiotherapist who performed the treatment was unaware of the objectives of the investigation. Patients were unaware of the group allocation. Furthermore, an unaware researcher performed data analysis.

Outcome Measures

The frequency, intensity, and duration of headache, the number of drug consumption, PPT, muscle thickness of the SCM muscle, and CROM were evaluated at 2 wks before the intervention, at the end of the intervention, and 1 mo after the intervention.

Daily Headache Diary

Subjects completed a daily headache diary recording headache frequency, intensity, and duration, and drug consumption.

• * Headache frequency was defined as the number of days that participants experienced a headache.²⁵
• * Headache intensity was rated on a scale of 0–5 (0, no pain; 1, there is pain only when considered; 2, there is pain, but it does not interfere with daily work; 3, there is pain and the subject cannot do work that needs concentration; 4, there is pain and it interferes with most of the daily work, so that the subject can do only the necessary tasks; and 5, there is maximum pain and the subject cannot do anything).²⁵
• * Headache duration was defined as the number of hours per day that subjects experienced headache.²⁵
• * Drug consumption was defined as the number of pain alleviating tablets used on days with headache.²⁵

Pressure Pain Threshold

Pressure pain threshold was assessed in the location of the MTrPs. An electronic pressure algometer (FG-5005, RS-232, Lutron Electronic Enterprise) was used to measure the PPT of TrPs before, after treatment, and at 1-mo follow-up. The algometer was used with perpendicular compression to the skin surface. The compression was stopped when the subject reported the “pain.” The average value of the three measurements was used for data analysis.²⁶ An intraclass correlation coefficient of 0.95 was obtained for the reliability of this device.

Muscle Thickness

The other variable was the thickness of the SCM muscle. It was measured by using B-mode US device (Honda 2100, Honda Co, Japan) with the frequency of 7.5 MHz and a linear array probe. The subjects were in supine position with head and neck placed in a neutral position. To measure the size of SCM, a linear array probe was used and transducer targeted at sites palpated at the physical examination in the SCM muscle. A line was drawn from the sternoclavicular joint to the mastoid process. The middle point of this line was considered as primary part of the SCM muscle trigger point (Figs. 3, 4). The middle point of the linear array probe was settled on this point longitudinally. In this position, proper imaging of the muscles, the right and left carotid artery, and vertebral lamina was seen.²⁷

FIGURE 3: Ultrasonography of the SCM muscle, position of the patient, and transducer.

FIGURE 4: Ultrasound image of SCM muscle in a migraine patient.

Active Cervical Range of Motion

The CROM was measured by a goniometer. The subjects sat in a chair with a backrest and the straight column resting on it. Then, it was requested to perform the active cervical movements of flexion, extension, left and right rotation, and left and right lateral flexion with the goniometer on their head, to the point of pain. They were objectively measured by a clinical goniometer.²⁸

Statistical Analysis

The Shapiro-Wilk test was used to assess normality and a normal distribution was considered to exist if the P value was 0.05 or greater. Descriptive statistics were performed on the demographic characteristics of the samples. Considerable differences in baseline characteristics between DN group and control group were assessed by using independent t tests. Differences in outcomes between DN group and control group were analyzed with 2 × 3 repeated-measure analyses of variance. When the main effecting time (before, immediately, and after 1-mo follow-up) was significant, the differences invariants between the two groups were assessed baseline, after the treatment, and at follow-up period. Significant findings from the 2 × 3 repeated-measure analysis of variance were followed with 2 × 2 pairwise post hoc analysis between each time point. The intraclass correlation coefficient was used to assess the intratester reliability of the measurement. Level of significance was considered at a P of less than 0.05. Statistical analysis was done using SPSS Version 23.

RESULTS

All of the variables had a normal distribution. Sixty-five participants were screened, but only 40 participants were enrolled in the study. Twenty participants allocated to the DN group and 20 participants to the placebo group. The mean of subjects’ age in the DN group was 36.10 ± 10.4 and in the control group was 37.45 ± 8.9. There was no significant difference in sex distribution, age, weight, and body mass index (Table 1).

TABLE 1 - Demographic data of the subjects

Variables	Control Group (n = 20)	DN Group (n = 20)	Pa
Age, yr	37.45 ± 8.94	36.10 ± 10.43	t = 0.43 0.66
Weight, kg	70.25 ± 6.71	67.25 ± 10.21	t = 1.09 0.28
Height, cm	1.70 ± 0.1	1.69 ± 0.09	t = 0.07 0.93
BMI	24.37 ± 2.46	24.04 ± 2.06	t = 0.46 0.64
Female/male	12/8	12/8	—

Data are presented as mean ± SD.

^aIndependent t test.

BMI, body mass index.

The intraclass correlation coefficient (first and third measurement) for repeat measures of the SCM muscle thickness was 0.84, measured using US.

The mean score of headache frequency, headache intensity, headache duration, and the number of drug consumption in the DN group was decreased after the intervention (P < 0.001) and at 1-mo follow-up (P < 0.001; Table 2). In addition, there was no change in these scores for the control group. The differences between both groups were significant after the intervention (P < 0.001) and at 1-mo follow-up (P < 0.001; Table 2).

TABLE 2 - Comparison of headache frequency, intensity, duration, drug consumption, PPT of SCM muscle, and muscle thickness of SCM between subjects of the two experimental groups in different phases

Variables		Control Group	DN Group	P 1 a	P 2 b Control Group		P 2 b DN Group		P 3 c		dd	η
					Before e -After f	Before-Follow-up g	Before-After	Before-Follow-up	After	Follow-up
Headache frequency	Before After Follow-up	3.50 ± 0.76 3.20 ± 0.83 3.30 ± 0.92	3.90 ± 0.78 1.80 ± 0.83 1.25 ± 0.71	<0.001	t = 1.55 0.13	t = 0.89 0.38	t = 13.07 <0.001	t = 20.18 <0.001	t = 5.31 <0.001	t = 7.84 <0.001	0.51 −1.67 −2.48	0.36
Headache intensity	Before After Follow-up	3.35 ± 0.74 3.20 ± 0.61 3.15 ± 0.48	3.80 ± 0.95 1.95 ± 0.82 1.80 ± 0.76	0.001	t = 0.76 0.45	t = 0.94 0.35	t = 14.09 <0.001	t = 13.78 <0.001	t = 5.42 <0.001	t = 6.63 <0.001	0.52 −1.71 −2.09	0.25
Headache duration	Before After Follow-up	31.30 ± 12.33 28.95 ± 12.15 29.60 ± 10.92	31.00 ± 9.48 17.55 ± 7.44 10.25 ± 5.27	0.001	t = 1.12 0.27	t = 0.93 0.36	t = 8.38 <0.001	t = 9.70 <0.001	t = 3.57 0.001	t = 7.13 <0.001	−0.02 −1.12 −2.25	0.26
Drug consumption	Before After Follow-up	6.50 ± 1.46 5.95 ± 1.09 6.15 ± 1.22	6.90 ± 1.20 2.45 ± 0.82 1.90 ± 0.85	<0.001	t = 1.92 0.06	t = 1.37 0.18	t = 21.07 <0.001	t = 21.79 <0.001	t = 11.38 <0.001	t = 12.73 <0.001	0.29 −3.60 −4.02	0.62
PPT of SCM muscle	Before After Follow-up	6.72 ± 0.77 6.40 ± 0.76 6.20 ± 0.77	5.70 ± 1.24 7.36 ± 1.25 8.49 ± 1.25	0.02	t = 18.44 <0.001	t = 21.42 <0.001	t = 20.28 <0.001	t = 16.06 <0.001	t = 2.89 0.006	t = 6.93 <0.001	−0.97 0.91 2.19	0.12
Muscle thickness of SCM	Before After Follow-up	7.85 ± 0.70 7.69 ± 0.67 7.62 ± 0.67	7.56 ± 0.72 8.79 ± 0.64 9.39 ± 0.60	<0.001	t = 3.20 0.005	t = 7.68 <0.001	t = 18.35 <0.001	t = 18.83 <0.001	t = 5.24 <0.001	t = 8.72 <0.001	−0.40 1.65 2.75	0.31

^aP value for repeated measurement.

^bP value for paired t test.

^cP value for independent t test.

^dCohen d.

^eBefore the intervention.

^fAfter the intervention.

^gOne month after the intervention.

The mean score of PPT of SCM muscle showed that this score trend increased immediately after intervention and at 1-mo follow-up (P < 0.001) but decreased in the control group (P < 0.001). The difference between the two groups was significant after the intervention (P = 0.006) and at 1-mo follow-up (P < 0.001; Table 2).

In the experimental group, the results revealed a significant increase of the muscle thickness of SCM immediately after intervention and at 1-mo follow-up of treatment (P < 0.001; Table 2). Besides, the control group decreased in the mean scores (P < 0.001). In addition, it was revealed a significant increase in the mean scores of immediately after and at 1-mo follow-up in the DN group, as compared with the control group (P < 0.001; Table 2).

Finally, the mean CROM scores for cervical flexion, extension, rotation, and lateral flexion increased in the DN group immediately after(P < 0.001) and at 1-mo follow-up of treatment (P < 0.001) but decreased in the control group (P < 0.001). The difference between the two groups was significant (P < 0.001; Table 3).

TABLE 3 - Comparison of cervical range of motions between subjects of the two experimental groups in different phases

Variables		Control Group	DN Group	P 1 a	P 2 b Control Group		P 2 b DN Group		P 3 c		dd	η
					Before e –After f	Before-Follow-up g	Before-After	Before-Follow-up	After	Follow-up
Flexion	Before After Follow-up	35.35 ± 1.84 32.95 ± 1.7 31.20 ± 1.39	33.05 ± 2.45 37.10 ± 2.31 40.15 ± 1.84	<0.001	t = 17.94 <0.001	t = 14.18 <0.001	t = 13.35 <0.001	t = 20.91 <0.001	t = 6.42 <0.001	t = 17.29 <0.001	−1.05 2.03 5.46	0.50
Extension	Before After Follow-up	25.15 ± 1.84 22.60 ± 1.78 20.20 ± 1.73	22.60 ± 3.08 26.40 ± 2.70 28.70 ± 3.04	<0.001	t = 15.02 <0.001	t = 21.08 <0.001	t = 16.90 <0.001	t = 19.87 <0.001	t = 5.24 <0.001	t = 10.84 <0.001	−1.00 1.65 3.42	0.33
Right rotation	Before After Follow-up	42.05 ± 3.01 38.95 ± 3.11 36.85 ± 3.03	40.30 ± 2.83 45.25 ± 2.98 48.90 ± 2.57	<0.001	t = 11.89 <0.001	t = 12.95 <0.001	t = 13.26 <0.001	t = 23.52 <0.001	t = 6.52 0.001	t = 13.55 <0.001	−0.59 2.06 4.28	0.50
Left rotation	Before After Follow-up	40.85 ± 3.01 38.10 ± 2.78 35.95 ± 2.96	39.25 ± 2.61 44.30 ± 2.77 48.70 ± 3.21	<0.001	t = 13.50 <0.001	t = 15.14 <0.001	t = 14.07 <0.001	t = 22.18 <0.001	t = 7.04 <0.001	t = 13.04 <0.001	−0.56 2.22 4.12	0.53
Right lateral flexion	Before After Follow-up	37.35 ± 3.01 34.55 ± 2.92 32.40 ± 2.50	35.05 ± 2.13 39.55 ± 1.70 43.10 ± 2.59	<0.001	t = 12.45 <0.001	t = 15.46 <0.001	t = 13.37 <0.001	t = 14.51 <0.001	t = 7.73 0.006	t = 13.81 <0.001	−0.88 2.08 4.20	0.48
Left lateral flexion	Before After Follow-up	36.70 ± 2.38 34.10 ± 2.10 32.00 ± 1.97	35.20 ± 2.64 40.60 ± 3.11 44.05 ± 3.36	<0.001	t = 13.17 <0.001	t = 14.10 <0.001	t = 11.71 <0.001	t = 17.03 <0.001	t = 5.24 <0.001	t = 8.72 <0.001	−0.59 2.44 4.36	0.58

^aP value for repeated measurement.

^bP value for paired t test.

^cP value for independent t test.

^dCohen d.

^eBefore the intervention.

^fAfter the intervention.

^gOne month after the intervention.

The Pearson coefficient showed a positive correlation between headache intensity, frequency, duration, drug consumption, PPT of MTrPs, and CROM with muscle thickness of SCM muscle (P < 0.05; Table 4).

TABLE 4 - The correlation between headache intensity, frequency, duration, drug consumption, PPT of SCM, and cervical ROM muscle with maximum thickness of SCM muscle

Dependent Variables	Independent Variables	Ra	Pb	Correlation
Maximum of thickness of SCM	Headache intensity	0.58	<0.001 c	Positive
	Headache frequency	0.60	<0.001 c	Positive
	Headache duration	0.63	<0.001 c	Positive
	Drug consumption	0.72	<0.001 c	Positive
	PPT of SCM	0.66	0.001 c	Positive
	Cervical ROM	0.69–0.79	<0.001 c	Positive

^aRelation.

^bP value for Pearson coefficient.

^cSignificant.

DISCUSSION

This study aimed to evaluate the effect of the DN into trigger points of SCM muscle in the migraine patients. A significant reduction in the headache parameters was observed after the application of DN. In addition, PPT level, CROM, and muscle thickness increased in the DN group. According to the current evidence, MTrPs treatment plays an important role in the management of migraine headache. To our knowledge, this was the first study dealing with the effect of DN on MTrPs into the SCM muscle of migraine patients. These results supported the effects of DN in the migraine headache, originating from MTrPs of SCM muscle. We found significant correlations between headache intensity, frequency, duration, drug consumption, PPT in the SCM muscle, and CROM with muscle thickness of SCM muscle. Hence, there was a positive relationship between decreased muscle thickness because of MTrPs biomechanical properties and migraine symptoms.

Possible mechanisms of why TrP therapy can be effective in reducing pain include a reduction of activity in a TrP, restoration of the length of muscle sarcomeres, reactive hyperemia within taut band of a TrP, elongation of the connective tissue, or reduction of sensitization substances associated with TrPs.²⁹ Patients experiencing migraine headache reported that referred pain from active TrPs in the SCM muscle reproduced the headache pattern. In such cases, the application of the DN can be an effective approach for these patients. The results found in this study would support the previously mentioned hypothesis.

Researchers had attributed the therapeutic effects of DN to various mechanisms, such as mechanical, neurophysiologic, and chemical effects.³⁰ Mechanical effects of DN may improve the fiber structure, the localized tissue stiffness, and the local circulation of the biochemical milieu associated with the trigger point.³⁰ The neurophysiological effect of DN may stimulate A-delta nerve fibers and may activate the enkephalinergic inhibitors of the dorsal interneurons that relieved pain.^30,31 For the chemical effect of DN, results of studies have indicated that increased levels of chemicals including bradykinin, substance p, and other chemicals at a TrP were directly corrected by creating local twitch response after DN.³¹

Studies have reported the reduction of symptoms in headache patients immediately after the treatment procedures for trigger points.^9,32 A mechanism supporting the use of DN in subjects with migraine headache may be related to the convergence of two peripheral systems of nociception: the trigeminal system and the cervical spinal nerves, particularly C1 to C3. A connection between trigger points of craniocervical area and migraine headache may be the activation of the trigeminal nerve nucleus. For example, TrPs located in any muscle innervated by the trigeminal nerve or the upper cervical nerves can precipitate or aggravate migraine attacks.³³ Moreover, our results were in line with other studies showing the effects of DN in patients with TrPs for deactivating MTrPs.

Because of different study designs and testing procedures, the effectiveness of the DN on myofascial pain was a controversial issue. In some studies, effect of this method was shown,^24,34 but in some cases, the treatment was ineffective.^35,36 Sedighi et al.³⁷ (2017) reported that the application of DN into trigger points of suboccipital and UT muscles induced significant improvement of headache index, trigger points tenderness, and range of motion in patients with cervicogenic headache. Furthermore, a systematic review on the effect of DN had focused on MTrPs associated with the neck and shoulder regions. They showed that the DN relieved MTrPs pain in the neck and shoulder muscles. However, the current study results gave confirmatory evidence in agreement with these studies. In addition, Martín-Rodríguez et al.³⁸ (2019) reported that TrP-DN of SCM muscle was associated with a decrease in pain after 1 wk and cervical motor control improved 1 mo after the intervention. Several dissimilarities with our study have to be highlighted in terms of primary outcomes measurement tools (headache parameters, ROM, PPT of SCM, and muscle thickness vs cervical motor control, neck disability index, and ROM), type of patients (migraine headache vs neck pain), and type of interventions (DN of inside SCM and placebo control groups vs DN of inside SCM and DN of outside SCM). The aim of current study was to evaluate the effect of treatment of SCM muscle on the headache parameters and muscle changes, but this study focused on the parameters of neck pain.³⁸

According to our results, it was reported that TrPs treatment of the SCM muscle decreased the pain scores and increased the PPT scores of the subjects; thus, the SCM muscle was shown to be associated with headache as Calandre et al.⁴ (2006) first reported. Results of current study reported increased effects in the PPT value in migraine patients after the DN treatment of trigger points. These changes could affect the spinal and supraspinal mechanisms as well as both peripheral and central mechanisms. The high-pressure stimulation of nociceptors during DN treatment in patients with muscle pain enhanced activity in the somatosensory and limbic regions associated with pain.³⁹ This activity was more enhanced when a trigger point was stimulated in the neck muscles in patients with myofascial pain syndrome than in control group within the same muscle.³⁹

On the other hand, a decrease in muscle thickness of SCM muscle may be due to the taut bands and MTrPs in this muscle. In line with our study, studies have shown the relationship between SCM muscle, unilateral neck pain, and headache. Barton and Hayes⁴⁰ (1996) found SCM weakness in patients with unilateral neck pain and headache. Decreased muscle thickness of neck flexor muscle was observed in patients with neck pain in comparison with healthy individuals.⁴¹ Other study reported higher fatigue of the SCM muscles in neck spine osteoarthritis.⁴² According to this study, the application of SCM DN increased the muscle size and decreased MTrP sensitivity.

Although the current study was one of the first studies to investigate the effect of DN on the clinical outcomes of a migraine headache, it had some limitations. First, the effects of other treatments, such as medications and manual therapy, were not investigated. In addition, this study included subjects with migraine headache, originating from MTrPs of SCM muscle. Thus, the results should not be generalized to all migraine patients. The short duration of therapy was one of the limitations of this study.

CONCLUSIONS

The application of DN technique caused an improvement in symptoms of migraine patients. The findings of this study suggest that headache parameters, PPT of SCM muscle, and active cervical range of motion may be in a direct relation with decreased muscle thickness of SCM muscle. Thus, this technique may be prescribed for treatment of migraine patients with MTrPs in the SCM muscle.