An Additive Effect of Instrument-Assisted Soft Tissue Mobilization with Spinal Manipulation in Cervicogenic Headache: a Randomized Controlled Trial

Abstract

Introduction

There is a multitude of evidence supporting the use of manual and manipulative therapy techniques for patients with cervicogenic headache (CGH). However, evidence in finding and comparing the efficacy of instrument assisted soft tissue mobilization with manual therapy in unilateral cervicogenic headache is lacking. Therefore, the objective of the study is to find and compare the long term effects of instrument assisted soft tissue mobilization along with spinal manipulation therapy in patients with cervicogenic headache.

Methods

It is a randomized, single-blinded controlled study conducted at University hospital. Overall, 64 participants with CGH were divided into spinal manipulation therapy group (SMT; n = 32) and spinal manipulation therapy with instrument assisted soft tissue mobilization (ISM) group (SMT + ISM; n = 32) and they received the respective treatment for 4 weeks. In addition, both groups received 10 min of heat therapy and neck isometric exercises three times a day. The primary (CGH frequency) and secondary (CGH pain intensity, CGH disability neck pain frequency, pain intensity, pain threshold, neck disability index and quality of life) scores were measured at baseline, after 4 weeks, and at 6 months.

Results

The reports of the SMT and SMT + ISM group were compared. Following 4 weeks of training, and at 6 months follow up the SMT + ISM group showed more significant changes in the primary outcome (CGH frequency) with a −4.3 [(95% confidence interval (CI) −4.80 to −3.79] and −1.7 (95% CI −1.92 to −1.47), when compared with the SMT group alone (p = 0.001). The secondary outcomes (CGH pain intensity, CGH disability, neck pain frequency, neck pain intensity, neck disability index, and quality of life) also shows more significant changes in the SMT + ISM group than the SMT group (p = 0.001). The same gradual improvement can be seen in the above variables at 6 months follow up. At the same time, neck pain threshold level does not show any improvement at 4 weeks (p ≥ 0.05) but shows a statistical difference at 6 months follow up. No such adverse effects or consequences were noted during or after the intervention.

Conclusions

The study concluded that spinal manipulation therapy with instrument assisted soft tissue mobilization provided better long-term outcomes in patients with cervicogenic headache. This study provided a piece of sound physical therapy evidence for a widespread and costly clinical condition, such as cervicogenic headache.

Clinical Trial Registration

The trial was registered prospectively in the Indian clinical trial registry with CTRI/2020/06/026243 on 30/06/2020.

Key Summary Points

This study found spinal manipulation combined with an instrument-assisted soft tissue mobilization approach provided better long-term outcomes in cervicogenic headache.

The study provided a piece of new evidence for the selection of exercise training protocols in cervicogenic headache in clinical practice.

These reports are helpful to physical therapists to prevent and treat the symptoms and consequences of cervicogenic headache.

Introduction

Headache is the most common symptom, affecting 90% of the world population. About 66% of men and 57% of women experience this pain at least once a year [1]. Cervicogenic headache (CGH) is a type of headache commonly caused by neck dysfunction, with the pain usually referred from the neck. These dysfunctions are difficult to define and quantify. Evidence suggests that the reliability of clinical procedures to identify such dysfunctions is poor. Some studies find an association between these dysfunctions and CGH [2]. CGH, also known as secondary headache, differs from migraine and mainly affects the general population, placing a considerable burden on public health and causing economic impact on communities [3]. The prevalence of CGH is 4.1%, making it one of the three most common recurrent headaches [4].

The basic steps in investigating cervicogenic headache involve obtaining subjective information and performing a physical examination [5]. Diagnostic criteria for cervicogenic headache include unilateral head ache, symptoms and signs of neck involvement, episodic moderate pain originating in the neck and spreading to the head, response to nerve or root blockade, and non-obligatory features, such as autonomic disturbances, dizziness, phonophobia, photophobia, monocular visual blurring, and difficulty swallowing [6]. The flexion-rotation test (FRT) is identified as a diagnostic tool for CGH and is a reliable and valid method for measuring upper cervical motion [7, 8]. Medical and pharmacological treatments, such as nonsteroidal anti-inflammatory drugs (aspirin or ibuprofen), muscle relaxants, and nerve blocks for CGH, are found to have harmful side effects [9]. There is a lack of safe, effective, and cost-efficient conservative treatments for CGH. A wide variety of holistic and nonpharmacological approaches are available, including patient education, ergonomic guidance, positional therapy, and strengthening exercises [10]. Evidence suggests that manual and exercise therapy may reduce headache intensity, frequency, and disability in both the short and long term for people with cervicogenic headache [11].

Manual therapy approaches for cervicogenic headache typically include joint mobilization and manipulation techniques [12]. Spinal manipulative therapy (SMT) is commonly used for neck-related pain and CGH. Recent studies and reviews support the wide application of SMT in CGH and show its superior effects compared with other treatments [13–15]. In recent times, manual therapists increasingly use instrument-assisted soft tissue mobilization (ISM), where specially designed tools are used to stretch soft tissues, relieve pain, and improve range of motion (ROM). This method reduces strain on the practitioner’s hand and allows deeper tissue penetration, effectively treating restricted fascia. ISM is used to treat different types of headaches. A study by Ramadan et al. finds that ISM improves headache symptoms and cervical alignment in patients with tension-type headaches, with improvements in headache frequency, headache under response to treatment (HURT), pressure pain threshold, and cervical lordosis angle [16].

There is ample evidence supporting the use of therapeutic exercises, manual, and soft tissue mobilization techniques for CGH [11, 17, 18]. However, evidence is lacking on the additive effects of instrument-assisted soft tissue mobilization for CGH, especially regarding clinical and functional outcomes. Additionally, prior studies on CGH have limitations, such as poor methodologies and small sample sizes, and there are few comparisons between different manual therapy approaches [18, 19]. To date, no studies address these limitations in CGH management.

The objective of our study is to compare the additive effects of instrument-assisted soft tissue mobilization with spinal manipulation on pain intensity, pain threshold, and pain frequency in patients with unilateral cervicogenic headache. We hypothesize that spinal manipulation therapy combined with instrument-assisted soft tissue mobilization will produce statistically and clinically significant outcomes compared with spinal manipulation therapy alone at a 6-month follow-up in cervicogenic headache. This study aims to provide valuable insights into these interventions and assist in rehabilitation settings to alleviate patient symptoms.

Methods

Trial Design

This study was a prospective, single-blinded, randomized, active-controlled trial. It commenced in July 2020, and the participants were screened by a neuro physician at the University hospital according to the cervicogenic headache diagnostic criteria 11.2.1, as defined by the International Classification of Headache Disorders (ICHD-3) [3, 6]. Using a computer-generated random table, 64 participants were randomized into two groups: the spinal manipulation therapy (SMT; n = 32) group and the spinal manipulation with instrument-assisted soft tissue mobilization (SMT + ISM; n = 32) group. The participants were assigned to their respective groups using 64 concealed envelopes through the block randomization method, handled by a blinded therapist.

The study followed the approved protocol, and no significant changes were made during its execution. The trial took place in the department of physical therapy, Prince Sattam bin Abdulaziz University, Al Kharj, Saudi Arabia. Ethical approval was obtained from the department’s ethical committee (DEC) with reference number RHPT/019/046. Both the study protocol and informed consent forms were approved by the DEC. The trial adhered to the ethical guidelines outlined in the 1964 Declaration of Helsinki and was prospectively registered in the Indian Clinical Trial Registry under CTRI/2020/06/026243 on 30 June 2020. The trial was conducted between July 2020 and December 2021.

Participants

Inclusion criteria:

• Unilateral CGH presentation,

• Age group above 18 years’ old,

• History of chronic CGH (> 3 months),

• CGH intensity ≥ 3 on a 10-point scale,

• CGH owing to cervical spine (neck) dysfunction,

• Reduced cervical motion in FRT and neck pain followed by headache,

• Neck stiffness and movement restriction patients were allowed to participate in the study, and

• No fracture, osteoporosis, deformities, and abnormalities on cervical spine image.

Exclusion criteria:

• Participants with other types of headache (migraine),

• Headache owing to other causes (sinus, tumor, neural, and tempero-mandibular joint issues),

• Had any type of physical therapy treatment in the past 3 months,

• Any contraindications to manual and manipulative therapy (fracture, instability, osteoporosis, arthropathy, and neural symptoms),

• Taking analgesics or corticosteroids and migraine-specific medications, such as triptans,

• Metastasis,

• Cardiac conditions (stroke, hypertension, and syncope),

• Neurological conditions (radiculopathy, myelopathy, and disc prolapse),

• Spinal cord problems, and

• Previous brain and spinal cord surgery patients were excluded.

The flow of the study program was recorded in accordance with the Consolidated Standards of Reporting Trials (CONSORT) guidelines and is shown in Fig. 1. Eligible participants were recruited from the University Hospital and King Khalid Hospital, Al-Kharj, Saudi Arabia.

Fig. 1.

Flow chart showing the study details

Interventions

In addition to the regular interventions, participants in the SMT group received spinal manipulation therapy, while participants in the SMT + ISM group received both SMT and ISM as part of their intervention. The two treatment groups received similar treatments, except for the addition of ISM, with respect to time allocated and information provided.

As per the study protocol, the interventions were provided by licensed physical therapists with 15–20 years of clinical experience in manual and manipulation therapy techniques. All participants in both groups were compensated by receiving free physical therapy treatment. First, the cervical vertebra joints and neck muscles of each participant were examined to identify joint dysfunction. Next, patients underwent 10 min of hydrocollator hot pack treatment at the base of the neck and upper shoulders to relax the muscles. After the hot pack application, the respective mobilization approaches were provided according to the study protocol. Participants were also taught and instructed to perform neck isometric exercises three times a day, every day. Intervention bias was minimized by using fixed treatment procedures, and standard forms were used to document treatment details and follow-up. All participants were instructed not to seek other forms of treatment during the study period. The treatment was administered four times per week for 4 weeks in both groups.

Spinal Manipulation Therapy

The SMT provided in the study followed the description by Peterson and Bergman. A trained manipulative therapist performed the technique after assessing each participant at every visit through physical examination and proper palpation. The therapist identified dysfunction sites in the cervical region using the FRT test and manipulated the region according to the study recommendations. Manipulation was not provided if the participant presented with any new contraindications to SMT or lacked clinical indications for SMT.

The participant lay comfortably in a supine position with arms and legs at the side and neck in a neutral position. The therapist stood at the head of the patient and cradled the patient’s head, placing one hand over the chin and the other on the posterior aspect of the occiput. Manipulation was performed in both directions, primarily targeting the upper cervical (C1–C2) vertebra. The movement was first directed away from the pain and then toward the pain. This bimanual technique involved premanipulation rotation of 30–45°, with the manipulation performed toward the side of pain using high-velocity, low-amplitude thrusts. The range of rotation depended on the level of the target vertebrae [20]. The intervention followed the World Health Organization (WHO) guidelines on basic training and safety in spinal manipulation to prevent undue effects.

Instrument-Assisted Soft-Tissue Mobilization

In ISM, the participant sat in a relaxed position, resting the forehead on folded hands placed on a plinth. Skin softener (Himalaya massage cream—Gold, New Delhi, India) was applied over the suboccipital and lateral neck regions to reduce friction and discomfort during the procedure. The M2T blade (Ontario, Canada), sterilized with alcohol-soaked cotton, was used for the procedure. The soft tissue restrictions in the cervical region were identified, and the restricted sites were noted. A fascial release was then performed using the M2T blade at a 45° angle in different planes, with strokes applied in the direction of the neck muscles without eliciting any symptoms. The technique targeted the levator scapula, sternocleidomastoid, scalene, and upper trapezius muscles from origin to insertion on both sides for 8 min. The same technique was applied over the longissimus capitis, splenius capitis, semispinalis capitis, and suboccipital muscles in a centripetal direction, repeated three times. The procedure was stopped immediately if the participant experienced any adverse effects, such as increased pain, discomfort, or abnormal sensations [21]. Participants were informed that mild soreness after manual therapy is normal.

All participants in both groups also received heat therapy. They were placed in a supine position with the neck in a neutral position. A heated hydrocollator pack, wrapped in a towel to protect the skin, was gently placed on the cervical region (base of the neck and upper shoulders), where muscle tension was likely contributing to the headache. The temperature was adjusted for comfort, and the pack was left in place for 10 min. Participants were also instructed to perform neck isometric exercises three times daily. They were to place the palm over the forehead and resist forward neck movement, holding the resistance for 10 s and repeating it 15 times. Similar resistance exercises were performed on the back and both sides of the head. Participants were advised to continue these exercises even after completing the 4 weeks of treatment. The intervention schedule is depicted in Fig. 2.

Fig. 2.

The study intervention schedule

Outcomes

The outcomes were measured at baseline, after 4 weeks, and at 6 months. These intervals provided a balanced view of both the immediate and longer-lasting effects of the interventions, which was crucial for understanding the efficacy and safety of these interventions in cervicogenic headache.

Primary Outcome

CGH frequency This was a self-reported measure, where patients with cervicogenic headache were asked to report the number of CGH days over 4 weeks in a medical logbook [22].

Secondary Outcome

CGH pain The intensity of CGH pain was measured using a 10-point visual analogue scale (VAS). Patients were asked to indicate their pain intensity on a 10 point scale, where 0 denoted “no pain” and 10 denoted “maximum intolerable pain.” This was a valid and reliable tool for measuring CGH pain intensity [23].

CGH disability The six-item headache impact test (HIT) questionnaire was used to measure the disability status of patients with cervicogenic headache. It was a valid and reliable tool [24].

Neck pain frequency This was a self-reported measure, where patients were asked to report the number of neck pain days over 4 weeks in a medical logbook [22].

Neck pain intensity The intensity of neck pain was measured using a 10-point visual analogue scale (VAS). Patients were asked to indicate their pain intensity on a 10 point scale, where 0 denoted “no pain” and 10 denoted “maximum intolerable pain.” This was a valid and reliable tool for measuring neck pain intensity [23].

Neck pain threshold The pain threshold was measured with a Digital Algometer (Wagner, Model FPX, USA), applied over a standard location (a trigger point on the upper trapezius muscle) in the neck region identified through palpation. This was a reliable and valid tool for measuring pain threshold [25].

Neck disability index (NDI) This was a valid and reliable self-reporting questionnaire consisting of 10 items, measured on a 0–5-point scale. Disability grades were determined on the basis of scores as follows: 0–4: no disability, 5–14: mild disability, 15–24: moderate disability, 25–34: severe disability, and 34 or more: complete disability [26].

Quality of life The EuroQol 5D (covering mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) was used as a psychometric questionnaire to measure the overall quality of life in patients with cervicogenic headache. The scale ranged from 0, representing the worst imaginable health state, to 100, representing the best imaginable health state [27].

Sample Size

The sample size was calculated using data from a previous study on the primary outcome of CGH days [28]. The required sample size was determined by assuming 80% power using a two-tailed test with a significance level of 0.05. To detect a minimum effect size of 1.5 CGH days, with a mean difference of 3.5 CGH days and a standard deviation of 0.7, the required sample size was 29 participants in each group. After considering a 10% dropout rate, the required sample size in each group increased to 32.

Randomization

An individual not involved in data collection performed the randomization. A total of 64 participants were randomized into SMT and SMT + ISM groups with a 1:1 allocation ratio. Randomization was conducted using a computer-generated random table, and participants were assigned to one of the two groups through sealed envelopes. All prospective participants who met the eligibility criteria were included in the study.

Blinding

Owing to the nature of the study, it was not feasible to blind the treating therapists or the participants. However, the therapists who assessed the outcome variables at baseline, 4 weeks, and 6 months were blinded. The therapist providing treatment and the one measuring outcomes were different individuals. The outcome-measuring therapist remained blinded to the participants’ group allocation throughout the study. Participants were also asked not to discuss their treatment with peers or the outcome-measuring therapist. Additionally, the authors did not have access to information that could identify individual participants during or after data collection.

Statistical Methods

Demographic characteristics of the participants were analyzed to determine the homogeneity of the study using the Kolmogorov–Smirnov test. Outcome data were presented as mean and standard deviation with a 95% confidence interval. The treatment effects at various intervals were analyzed using a 2 × 3 mixed model analysis of variance (ANOVA), with the treatment group (spinal manipulation and spinal manipulation with ISM) and time intervals (baseline, 4 weeks, and 6 months). Repeated measures ANOVA was performed to identify significant differences within the groups. An independent t-test was used for between-group comparisons, with statistical significance set at p < 0.05. All statistical analyses were conducted using SPSS software (version 20.0), SPSS Inc., Chicago, Illinois, USA.

Results

Participants

Out of 88 participants screened, 6 participants with a score of more than 8 on the VAS scale, 8 with musculoskeletal and other joint injuries, 2 awaiting surgery, and 8 not willing to participate in the study were excluded. In total, 64 patients were selected as per eligibility criteria and allocated equally into two groups. Two participants in the SMT group (one owing to personal reason and one owing to time constraint) and three participants in the SMT + ISM group (two owing to personal reason and owing due to travel issues) did not complete the 4 week treatment program with 6-month follow-up (Fig. 1) and intention to treat analysis was presumed to be in the study analysis. The other potential confounding factors, such as age, sex, baseline headache severity, other medical conditions, and medication use, were controlled by randomization method and control in the statistical tests. In this trial, females (53–59%) are affected more than males in both groups. The clinical variables, such as CGH duration, CGH frequency, and CGH intensity, also have not shown any significant difference between the groups (p ≥ 0.05) at baseline and most of the CGH cases have associated (81–88%) neck pain (Table 1).

Table 1.

Demographic details of SMT and SMT + ISM groups

Variable		SMT Mean ± SD	SMT + ISM Mean ± SD
Age (year)	–	36.2 ± 4.1	35.8 ± 3.9
Sex	Male	15 (47%)	13 (41%)
	Female	17 (53%)	19 (59%)
Height (cm)	–	165.2 ± 3.6	164.1 ± 3.8
Weight (kg)	–	73.56 ± 5.1	72.89 ± 4.9
BMI (kg/m2)	–	24.2 ± 1.91	23.9 ± 2.06
CGH duration (year)	–	5.2 ± 2.1	5.5 ± 2.4
CGH frequency (per day)	–	0.78 ± 0.13	0.75 ± 0.12
CGH intensity (0–10)	–	6.5 ± 1.2	6.4 ± 1.4
Neck pain	Yes	26 (81%)	28 (88%)
	No	6 (19%)	4 (12%)

SD standard deviation, SMT spinal manipulation therapy, ISM instrument assisted soft tissue mobilization, BMI body mass index, CGH cervicogenic headache

The baseline data on CGH frequency, CGH pain intensity, and CGH disability score between the SMT and SMT + ISM groups showed no statistical difference (p ≥ 0.05), which indicated homogeneous distribution. Table 2 showed the mean and standard deviation (SD) of the variables, for the two groups, at three time intervals. A 2 × 3 mixed model ANOVA showed significant difference in CGH frequency (p = 0.028, ${\eta }_{\text{p}}^2$ = 0.088), CGH pain intensity (p = 0.038, ${\eta }_{\text{p}}^2$ = 0.091), and CGH disability (p = 0.056, ${\eta }_{\text{p}}^2$ = 0.019).

Table 2.

Pre and post mean and standard deviation of outcome measures of SMT and SMT + ISM group

Variable		SMT Mean ± SD	SMT + ISM Mean ± SD	p value
CGH frequency (no. of days per 4 weeks)	Baseline	15.6 ± 1.5	16.1 ± 1.4	0.173
	4 weeks	10.5 ± 1.1	6.2 ± 0.9	0.001**
	6 months	3.5 ± 0.5	1.8 ± 0.4	0.001**
	p value	0.001**	0.001**
CGH pain intensity (0–10)	Baseline	6.8 ± 0.9	7.1 ± 1.1	0.237
	4 weeks	4.5 ± 0.6	3.1 ± 0.4	0.001**
	6 months	0.8 ± 0.2	0.3 ± 0.3	0.001**
	p-value	0.001**	0.001**
CGH disability	Baseline	56.32 ± 7.1	57.03 ± 7.2	0.692
	4 weeks	47.11 ± 6.1	41.42 ± 5.9	0.001**
	6 months	32.62 ± 4.1	28.72 ± 3.9	0.001**
	p value	0.001**	0.001**
Neck pain frequency (no. of days per 4 weeks)	Baseline	23.6 ± 3.4	23.8 ± 3.8	0.825
	4 weeks	16.1 ± 2.5	14.3 ± 2.2	0.003**
	6 months	3.8 ± 0.6	2.2 ± 0.3	0.001**
	p value	0.001**	0.001**
Neck pain intensity (0–10)	Baseline	6.9 ± 0.6	7.2 ± 0.7	0.070
	4 weeks	4.9 ± 0.5	3.2 ± 0.6	0.001**
	6 months	0.9 ± 0.3	0.2 ± 0.1	0.001**
	p value	0.001**	0.001**
Neck pain threshold	Baseline	263.3 ± 20.7	262.2 ± 21.1	0.834
	4 weeks	267.6 ± 19.1	270.2 ± 21.2	0.608
	6 months	282.3 ± 15.1	292.3 ± 17.2	0.016**
	p value	0.001**	0.009
Neck disability index	Baseline	51.25 ± 12.2	52.13 ± 11.4	0.766
	4 weeks	43.19 ± 10.1	35.54 ± 10.2	0.003**
	6 months	12.11 ± 4.5	08.23 ± 3.4	0.000**
	p value	0.001**	0.001**
Quality of life (EuroQol 5D) (0–100)	Baseline	58.12 ± 6.8	57.96 ± 6.3	0.922
	4 weeks	73.12 ± 7.1	66.83 ± 6.7	0.001**
	6 months	86.27 ± 8.6	75.63 ± 7.0	0.001**
	p value	0.001**	0.001**

SD standard deviation, EuroQol 5D European Quality of Life 5 Dimension, SMT spinal manipulation therapy, ISM instrument assisted soft tissue mobilization, CGH cervicogenic headache

**Significant

Over 4 weeks of different treatment protocols, there is significant improvement (p = 0.001) in SMT group in pain frequency [4.3; 95% confidence interval (CI) −4.80 to 3.79], pain intensity (−1.4; 95% CI −1.65 to 1.14), and CGH disability (−5.69; 95% CI −8.68 to 2.69) than SMT + ISM group in pain frequency (−1.7; 95% CI −1.92 to −1.47), pain intensity (−0.5; 95% CI −0.62 to −0.37), and CGH disability (−3.9; 95% CI −5.89 to −1.90]). The same gradual improvement can be seen in 6-month follow-up period (Table 3). The standard mean difference showed a higher percentage improvement in pain frequency, pain intensity, and disability level in the SMT + ISM group than in the SMT group. The whole analysis shows little tendency toward greater improvement for the SMT + ISM group than the SMT group in primary variables (Fig. 3).

Table 3.

Pre and post mean difference scores of SMT and SMT + ISM group

Variable / Time	Baseline	4 weeks	6 months
	SMT versus SMT + ISM mean difference CI 95% (upper limit–lower limit)
CGH Frequency (95% CI)	0.5 (−0.22 to 1.22)	−4.3 (−4.80 to −3.79)	−1.7 (−1.92 to −1.47)
CGH Pain Intensity (95% CI)	0.3 (−0.20 to 0.80)	−1.4 (−1.65 to −1.14)	−0.5 (−0.62 to −0.37)
CGH Disability (95% CI)	0.7 (−2.86 to 4.28)	−5.69 (−8.68 to −2.69)	−3.9 (−5.89 to −1.90)
Neck pain frequency (95% CI)	0.2 (−1.60 to 2.0)	−1.8 (−2.97 to −0.62)	−1.6 (−1.83 to −1.36)
Neck pain intensity (95% CI)	0.3 (−0.02 to 0.62)	−1.7 (−1.97 to −1.42)	−0.7 (−0.81 to −0.58)
Neck pain threshold (95% CI)	−1.1 (−11.54 to 9.34)	2.6 (−7.48 to 12.68)	10 (1.91 to 18.08)
Neck disability index (95% CI)	0.88 (−5.02 to 6.78)	−7.6 ( −12.72 to −2.57)	−3.88 (−5.87 to −1.88)
Quality of life (95% CI)	−0.1 (−3.43 to 3.11)	−6.2 (−9.73 to −2.84)	−10.6 (−14.55 to −6.72)

CI confidence interval, SMT spinal manipulation therapy, ISM instrument assisted soft tissue mobilization, CGH cervicogenic headache

Fig. 3.

Pre and post-mean and standard deviation scores primary and secondary variables of SMT and SMT + ISM group

The baseline data on all the other variables, such as neck pain frequency, neck pain intensity, neck pain threshold, neck disability index, and quality of life scores between the two groups shows no statistical difference (p ≥ 0.05). Table 2 showed the mean and standard deviation (SD) of secondary variables, for the two groups, at three time intervals. A 2 × 3 mixed model ANOVA showed significant difference in neck pain frequency (p = 0.012, ${\eta }_{\text{p}}^2$ = 0.052), neck pain intensity (p = 0.001, ${\eta }_{\text{p}}^2$ = 0.043), neck pain threshold (p = 0.021, ${\eta }_{\text{p}}^2$ = 0.091), flexion rotation test (Right and left) (p = 0.004, 0.011, ${\eta }_{\text{p}}^2$ = 0.026. 0.032), neck disability index (p = 0.005, ${\eta }_{\text{p}}^2$ = 0.028), and quality of life (p = 0.005, ${\eta }_{\text{p}}^2$ = 0.034).

Over 4 weeks of different treatment protocols, there is significant improvement (p = 0.001) in SMT group in neck pain frequency (−1.8; 95% CI −2.97 to −0.62), neck pain intensity (−1.7; 95% CI −1.97 to −1.42), neck pain threshold (2.6; 95% CI −7.48 to 12.68), neck disability index (−7.6; 95% CI −12.72 to −2.57), and quality of life score (−6.2; 95% CI −9.73 to −2.84) compared with the SMT + ISM group in neck pain frequency (−1.6; 95% CI −1.83 to −1.36), neck pain intensity (−0.7; 95% CI −0.81 to −0.58), neck pain threshold (10.0; 95% CI 1.91 to 18.08), neck disability index (−3.88; 95% CI −5.87 to −1.88), and quality of life score (−10.6; 95% CI −14.55 to −6.72), as shown in Table 3. The standard mean difference showed a higher percentage improvement in all secondary variables in the SMT + ISM group than in the SMT group. The whole analysis shows a little tendency toward greater improvement for the SMT + ISM group than the SMT group in other variables (Fig. 3).

Adverse reactions: no such adverse effects or consequences were noted during or after the intervention.

Discussion

The current randomized trial investigated the difference in patient-reported outcomes for CGH between patients receiving SMT and those receiving SMT combined with ISM. We found significant improvements in all patient-reported outcomes at 4 weeks and 6 months in both groups, with more pronounced improvements in the SMT + ISM group. The data suggested that spinal manipulation therapy combined with instrument-assisted soft tissue mobilization provided statistically and clinically better outcomes than spinal manipulation therapy alone for unilateral cervicogenic headache at the 6-month follow-up. The cervical spine is a complex structure of joints that allows greater mobility compared with other parts of the spine, making it more susceptible to various disorders and complications, often leading to misalignment issues and cervical dysfunctions [29, 30]. In cases of cervical dysfunction, patients typically experience cervicogenic headache, neck pain, reduced cervical range of motion, and disturbed functional activities [31].

The results of this study showed improvement in both primary and secondary outcomes after spinal manipulation therapy in patients with cervicogenic headache. SMT significantly improved pain frequency (MCID = 12.1), which was consistent with previous studies by Giles and Muller et al. [32]. Cassidy et al. found that SMT was more effective than other mobilization techniques in reducing pain [33]. Spinal manipulation was also suggested to accelerate the recovery process in CGH. According to Fernández de Las Peñas et al., SMT inhibited the nociceptive fibers in the facet joints, intervertebral discs, paravertebral muscles, and soft tissues, thereby reducing pain and improving joint range. The high-velocity thrust maneuver activated joint receptors and inhibited the pain pathway through the pain gate mechanism. Biomechanical changes also impacted sensory receptors, such as muscle spindles and Golgi tendon organs, relaxing muscles, and reducing soreness [34]. Despite numerous studies on SMT, the exact biomechanical and neurophysiological mechanisms behind its effects remain to be explored.

This study found that 4 weeks of spinal manipulation combined with instrument-assisted soft tissue mobilization (ISM) had a significant effect on both primary and secondary variables in patients with cervicogenic headache. ISM played an effective role in treating CGH (MCID = 14.3) and associated neck pain, in addition to spinal manipulation therapy. A recent study reported that such mobilizations helped treat tension-induced headaches and reduced headache frequency, which was also noted in this study. The changes in this group could be attributed to increased tissue temperature and blood flow caused by friction between the device and tissue [35]. ISM also helped stretch tight fascia by breaking adhesions and abnormal cross-links, relieving pressure on pain nerve fibers and increasing joint mobility. It activated the opioid and oxytocin interaction, promoting an anti-nociceptive reaction. Another important mechanism of ISM in CGH was the desensitization of the trigeminocervical nucleus, which played a crucial role in reducing the tone of suboccipital and neck muscles [36].

Intra-group analysis showed that both SMT and SMT + ISM had longer-lasting and better effects at 6 months compared with 4 weeks, potentially owing to the natural history of CGH or the Hawthorne effect [37]. The findings of this study will be useful for physical therapists and chiropractors in selecting evidence-based treatment approaches for patients with cervicogenic headache, and in the decision-making process. To the best of our knowledge, this was the first study to collect clinical symptoms of CGH and its associated neck problems after different treatment protocols. The study also supported the safety of applying spinal manipulative therapy in patients with cervicogenic headache [38, 39].

The study had certain limitations. First, although the sample size was calculated through power analysis, the authors felt it was small. The calculation was based only on the primary outcome, so secondary outcomes may have been underpowered, increasing the risk of a type 2 error. Second, while both sexes were included, the data were not analyzed separately, meaning sex differences may have impacted the outcomes. The study was not adequately powered for sex subgroups. Third, the lack of a placebo group limited the assessment of the actual efficacy of the intervention. Fourth, adding ISM took more time, so future studies should explore its cost–benefit. Lastly, the study was difficult to reproduce since the treatment was on the basis of the therapist’s judgment. Future research should analyze the beneficial effects of different mobilization and manipulation techniques on pain and other symptoms in patients with cervicogenic headache, including a placebo group. Additionally, further research is recommended to explore the physical and molecular mechanisms behind the clinical and physiological effects of these approaches in patients with cervicogenic headache.

Conclusions

The study concluded that spinal manipulation combined with instrument-assisted soft tissue mobilization and therapeutic exercises provided better long-term effects in patients with cervicogenic headache symptoms. This research contributed to a better understanding of cervicogenic headache and provided clinical evidence for selecting the appropriate manual therapy technique for these patients.

Author Contributions

Gopal Nambi, Mshari Alghadier, Humaira Khanam, Shahul Hameed Pakkir Mohamed, Osama R. Aldhafian, Naif A. Nwihadh, Paramasivan Mani, Mohamed Faisal Chevidikunnan, Fayaz Khan, and Alaa Jameel A. Albarakati conceptualized the study and carried out the methodology and writing—review and editing; Mshari Alghadier, Humaira Khanam, Osama R. Aldhafian, Naif A. Nwihadh, Mohamed Faisal Chevidikunnan, Fayaz Khan, and Alaa Jameel A. Albarakati carried out data curation; Gopal Nambi, Mshari Alghadier, Humaira Khanam, Shahul Hameed Pakkir Mohamed, Paramasivan Mani, Mohamed Faisal Chevidikunnan, Fayaz Khan, and Alaa Jameel A. Albarakati carried out the formal analysis; Gopal Nambi, Mshari Alghadier, Humaira Khanam, Shahul Hameed Pakkir Mohamed, Osama R. Aldhafian, and Naif A. Nwihadh acquired the resources; Gopal Nambi, Mshari Alghadier, Humaira Khanam, Shahul Hameed Pakkir Mohamed, Mohamed Faisal Chevidikunnan, Fayaz Khan, and Alaa Jameel A. Albarakati performed funding acquisition; Gopal Nambi, Mshari Alghadier, Humaira Khanam, Osama R. Aldhafian, Naif A. Nwihadh, Mohamed Faisal Chevidikunnan, and Fayaz Khan performed the investigation; Software: Shahul Hameed Pakkir Mohamed, Osama R. Aldhafian, Naif A. Nwihadh, Paramasivan Mani, Mohamed Faisal Chevidikunnan, Fayaz Khan, and Alaa Jameel A. Albarakati SP, OA, NN, PM, MC, FK, AA carried out project administration; Humaira Khanam, Shahul Hameed Pakkir Mohamed, Paramasivan Mani, Mohamed Faisal Chevidikunnan, Fayaz Khan, and Alaa Jameel A. Albarakati HK, SP, PM, MC, FK, AA carried out validation; Gopal Nambi, Shahul Hameed Pakkir Mohamed, Osama R. Aldhafian, Naif A. Nwihadh, and Alaa Jameel A. Albarakati GN, SP, OA, NN, AA carried out visualization; Gopal Nambi, Mshari Alghadier, Osama R. Aldhafian, Naif A. Nwihadh, Paramasivan Mani, Mohamed Faisal Chevidikunnan, Fayaz Khan, and Alaa Jameel A. Albarakati GN, MA, OA, NN, PM, MC, FK, AA carried out writing—original draft.

Funding

This study is supported via funding from Prince Sattam bin Abdulaziz University project number PSAU/2023/R/1444 and the article fee will be waived.

Data Availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Declarations

Conflict of Interest

Gopal Nambi, Mshari Alghadier, Humaira Khanam, Shahul Hameed Pakkir Mohamed, Osama R. Aldhafian, Naif A. Nwihadh, Paramasivan Mani, Mohamed Faisal Chevidikunnan, Fayaz Khan, and Alaa Jameel A. Albarakati have nothing to disclose.

Ethical Approval

The ethical approval was obtained from the department ethical committee (DEC) with the reference number RHPT/019/046. The trial adhered to the ethical guidelines outlined in the 1964 Declaration of Helsinki and was registered prospectively in the Indian clinical trial registry with CTRI/2020/06/026243 on 30/06/2020.