Buccal acupuncture combined with ultrasound-guided dry needle-evoked inactivation of trigger points to treat cervical and shoulder girdle myofascial pain syndrome

Abstract

BACKGROUND:

Myofascial pain syndrome (MPS) is a common disease with easy persistence and recurrence. In clinical practice, although many methods have been adopted to prevent and treat MPS, the control of MPS is still not satisfactory.

OBJECTIVE:

To compare the safety and effectiveness of buccal acupuncture, inactivation of trigger points (MTrPs), and their combination in the treatment of MPS.

METHODS:

Two hundred MPS patients in the pain clinic were randomly divided into four groups ( $n=$ 50) to receive oral drugs (Group A), oral drugs $+$ buccal needle (Group B), oral drugs $+$ MTrP inactivation (Group C), or oral drugs $+$ buccal needle $+$ MTrP inactivation (Group D).

RESULTS:

The visual analogue scale (VAS) and cervical range of motion (ROM) of Group D were significantly lower than those of the other three groups, and the pressure pain threshold (PPT) value of labelled MTrPs was significantly higher than those of the other three groups ( $P<$ 0.05). The excellent rate and total effective rate of Group D were significantly higher than those of the other three groups. Group C had the highest pain score and the lowest acceptance score. The results showed that buccal acupuncture combined with ultrasound-guided dry needle-evoked inactivation of MTrPs can significantly reduce the VAS score of MPS patients, improve the range of motion of the cervical spine, and improve patient satisfaction.

CONCLUSIONS:

This study provides a highly accepted and satisfactory treatment for MPS, which is worthy of clinical promotion.

Keywords

Acupuncture myofascial pain syndrome oral drugs dry needle pain

1. Introduction

Buccal acupuncture is a new microneedle system created by Professor Wang Yongzhou and his team [1] that can be used to treat diseases by needling specific acupoints on the cheek, especially diseases with pain of the head, trunk, and limbs as the major symptom [2, 3]. Buccal acupuncture is well received by doctors and patients for its simple acupoint selection, immediate analgesia, safety, and painlessness Cervical and shoulder girdle myofascial pain syndrome (MPS) is a common clinical syndrome of cervical and shoulder muscle disorders that gradually occurs based on chronic strain and attacks continuously or intermittently, with the main symptoms of soreness, numbness, swelling, and pain. It is characterized by the presence of one or more myofascial trigger points (MTrPs) [4]. MTrPs are highly sensitive tenderness nodules in the tight band of skeletal muscle. Active MTrPs (active trigger points, A-MTrPs) show spontaneous pain, while latent MTrPs (latent trigger points, L-MTrPs) can cause pain only by external pressure. Generally, there are potential MTrPs in every muscle of the human body. These potential MTrPs can be activated due to trauma, acute over-traction, overwork, cold, decreased resistance, and other factors. These potential MTrPs show tension, soreness, referred pain, and local convulsion reaction of related muscles. How to accurately locate and effectively inactivate MTrPs is the key to the treatment of MPs. There are many methods for the localization of MTrPs. Compared with traditional manual palpation and expensive MRI, which is not suitable for routine clinical use, ultrasound technology is increasingly popular for its convenience, speed, accuracy, and real-time guidance [5]. The inactivation methods of MTrPs include dry needles, wet needles, massage, acupuncture, and extracorporeal shock wave therapy (ESWT) [6, 7]. The research team once used ESWT in combination with trigger point injection therapy to treat cervical and shoulder girdle myofascial pain syndrome [8], and the results showed that despite the treatment effect, patient acceptance was low since the patients were very painful during ESWT treatment, and they were worried about the adverse reactions of trigger point injection. Considering the painless needling and the immediate analgesic effect of buccal acupuncture, this study intends to use buccal acupuncture combined with ultrasound-guided dry needle-evoked inactivation of trigger points to treat cervical and shoulder girdle myofascial pain syndrome and carry out a comparative study and observation.

2. Materials and methods

2.1 General materials

Two hundred patients with cervical and shoulder girdle myofascial pain syndrome were selected, including 96 males and 104 females who were aged 18 $\sim$ 70 years, had a treatment course of three months to five years and were diagnosed and treated at the pain clinic of the First Affiliated Hospital of Suzhou University. Patients were randomly assigned into four groups. There were 50 patients in each group. Group A: Basic treatment group (a two-week oral medication group); Group B: a two-week oral medication combined with buccal acupuncture group; Group C: a two-week oral medication combined with ultrasound-guided dry needle-evoked inactivation of trigger point group; Group D: a two-week oral medication combined with the trigger point inactivation group after buccal acupuncture treatment. All patients signed an informed consent form and the research protocol was approved by the Ethics Committee of the First Affiliated Hospital of Suzhou University. The trial was registered on Clinicaltrials.gov under ChiCTR2100045357.

The disease was confirmed according to the MPS diagnostic criteria put forward by David et al. in Pain Medicine in 2015 [9], with pain in the neck and shoulders. All patients were given basic treatment for two weeks on the day of the first visit. The basic treatment is oral nonsteroidal anti-inflammatory analgesics (celecoxib capsules, 0.2 g, q12 h).

2.2 Exclusion criteria

(1) Patients with concomitant acute soft tissue injury or infection, cervical spondylosis, frozen shoulder, and immune diseases, including rheumatic disease. (2) Those with a bleeding tendency or limitation in using anticoagulants. (3) Those having concomitant severe cardio- and cerebrovascular diseases and liver and kidney failure and intolerable to stimulation. (4) Those with language, hearing, or mental disorders and unable to receive treatment and follow-up. (5) Those dropping out during treatment. (6) Those in pregnancy or lactation. In addition, patients taking anti-inflammatory analgesics were enrolled after wash-out for one week.

2.3 Treatment methods

Figure 1.

Buccal acupuncture and ultrasound-guided dry needle inactivation of MTrPs. (A) Shoulder points. (B) Neck points. (C) Back points. (D) Head points. (E) Upper Jiao. (F) Middle Jiao. (G) Lower Jiao. (H) Holography of upper limbs (elbow). (A1, A2): Shoulder points (intensified). Arrow: Dry needle. Star: MTrPs. (a) Miniature holographic projection of human body on the cheek. (b) Localization of basic acupoints in buccal acupuncture. (c) Basic needle arrangement of buccal acupuncture to treat MPS, neck, shoulders and back. (d) Head points punctured in addition for MPS patients with mental symptoms like insomnia and depression. (e) Triple Jiao points punctured in addition for MPS patients with positive results in abdominal examination and urine and feces abnormalities. (f) Holographic points of the upper limbs punctured in addition and shoulder points punctured once again for MPS patients with pain radiating to the upper limbs.

Before treatment, the patients in each group were given a detailed physical examination to determine the locations and numbers of MTrPs and make clear marks. MTrPs were mainly diagnosed by [5], hard and cord-like tension bands in skeletal muscles, highly sensitive MTrPs in the bands, dull pain or sharp pain due to stimulation of MTrPs, accompanied by local convulsion reaction, and spontaneous or induced referred pain. For patients in Groups B and D the abdominal examination was performed [10], urine, faeces, and sleep of the patients were inquired about in detail, and their mental state was assessed so that points for buccal acupuncture could be selected.

2.4 Buccal acupuncture

Points were selected according to “Buccal Acupuncture Therapy” [10]. The basic acupoints included the neck point on the affected side (located straight above the midpoint of the mandibular condyle and intersecting with the upper edge of the zygomatic arch), shoulder point (midpoint of the zygomatic arch), and back point (located at the lower edge of the zygomatic arch root under the temporomandibular joint) (Fig. 1c). If the pain radiated to the upper limb, holographic acupuncture of the affected limb was added (Fig. 1f). If abdominal examination showed positive results with abnormal urination and defecation, the corresponding Jiao points were also selected (the upper Jiaopoint was the intersection point of the posterior part of the mandible coronoid process with the lower edge of the zygomatic arch, the middle Jiao point was the middle point of the line between the upper Jiao point and the lower Jiao point, and the lower Jiao point was the front edge of the mandibular internal angle) (Fig. 1e). If the patient had mental symptoms such as insomnia and depression, the head point was also selected (1 Cun above the upper edge of the zygomatic arch middle point) (Fig. 1d).

Figure 2.

MTrPs appeared as hyperechoic areas in two-dimensional ultrasound observation. Arrow: dry needle. Star: MTrPs. (a) MTrPs showing oval, locally heterogeneous hyper echoic areas in two-dimensional ultrasound observation. (b) Local echoes attenuated and tangled muscles untangled and relaxed after repeated puncturing of MTrPs with dry needle.

Figure 3.

Elastic ultrasound showed the inactivation of MTrPs. (a) Fixed the same position for comparison before and after ultrasound scan. (b) Marked MTrPs (the blue box is the placement position of the ultrasound probe, the star mark is the position of the MTrPs). (c) Ultrasound fixed position. (d) Scanning was performed using two-dimensional ultrasound, MTrPs showed oval heterogeneous hypoechoic, and elastic ultrasound images showed that MTrPs was an oval green area. (e) White ellipse indicates MTrPs. (f) The dry needle under ultrasound guidance inactivated MTrPs (the white arrow indicates the dry needle, the blue arrow indicates the needle tip). (g) After inactivation of MTrPs with dry needle, the elastosonographic images showed that the area where MTrPs were located changed from green to red. (h) buccal needle treatment position (A: shoulder points, B: neck points, C: back points). (i) After buccal acupuncture treatment for 30 minutes, the elastic ultrasound image showed that the area where MTrPs was located became weaker in green and gradually turned to red.

Manipulation: Routine facial disinfection was performed, and Lejiu trocar acupuncture needles 0.18 mm $\times$ 30 mm (Debang Medical Equipment Co., Ltd., Shenzhen, China; Batch no 1809001) were used. The needle was inserted quickly and vertically without obtaining qi. The needle was inserted once every two minutes and kept for 30 minutes. The patients were instructed to perform active and passive forward flexion, backward extension, and left and right rotation movements of the neck, and they were assisted to perform passive traction on corresponding muscles to observe the degree of pain relief. Appropriate painless adjustment and supplementation of needling could be carried out according to patients’ reactions.

2.5 Ultrasound-guided dry needle-evoked inactivation of MTrPs

Using a HuashengLabat ultrasonic (Shenzhen, China) high-frequency probe, with the marking point located in the centre of the ultrasonic probe, in-plane technology was used for real-time guidance. MTrPs showed oval, locally heterogeneous hypoechoic (Fig. 3d and f) or significantly hyperechoic areas in two-dimensional ultrasound observation [11] (Fig. 2). In addition, a new ultrasonic elastography technology was used to detect the elastic coefficient of the tissue in the MTrP area. The result of the elastic coefficient is converted into a real-time colour image. When the tissue is soft, the elastic coefficient is small, and the tissue appears red. When the tissue is stiff, the elastic coefficient is large, and the tissue is blue, and when the elastic coefficient is medium, the tissue appears green. Lejiu edgewise needles 0.35 $\times$ 70 mm (Debang Medical Equipment Co., Ltd.; Batch no. CB3575R) were used to repeatedly puncture the MTrPs under ultrasound guidance until there was obvious aching and swelling pain. If local twitch responses (LTRs) could be induced, the points were punctured as many times as possible until LTRs could not be induced. The standard of dry needle inactivation of MTrPs was as follows: aching and swelling pain induced by MTrP puncturing was resolved or significantly reduced, and LTRs disappeared. At the same time, elastic ultrasound imaging showed that the elastic coefficient of the tissue in the MTrP area decreased, and the local tissue appeared blue or changed from green to red (Fig. 3f and g).

MTrP pain sensitivity test: The pressure pain threshold (PPT) was measured using a hand-held pressure pain metre, each point was measured in triplicate at 10-minute intervals, and the average value was obtained. Given the large difference in pain sensitivity of each MTrP, in this study, the MTrP with the lowest PPT value measured at T0 among all MTrPs in each patient was selected as the observation target for the comparative study before and after treatment.

In Group C, a physical examination was performed after buccal acupuncture. Ultrasound-guided dry needle-evoked inactivation was performed only on MTrPs with obvious tenderness (PPT value $<$ 2.5) after treatment with buccal acupuncture. The difference in the number of MTrPs before and after buccal acupuncture was recorded (after buccal acupuncture treatment, the local tissue PPT value of MTrPs was more than 2.5, and elastic ultrasound imaging showed that the elastic coefficient of the tissue in the MTrP area decreased, and the local tissue appeared blue or changed from green to red, which was considered to have been inactivated) (Fig. 3h and i). The difference rate was calculated as follows: difference rate $=$ pretreatment number $-$ posttreatment number/pretreatment number. Treatment was given once a week for a total of three times in the three groups.

2.6 Outcome measures

(1) VAS scores of cervical vertebrae were recorded during follow-up before initial treatment (T0) and immediately (T1), one week (T2), two weeks (T3), and three weeks (T4) after initial treatment. The ROM score of cervical vertebrae and PPT of labelled MTrPs were recorded at T and T4. Excellent and good rates of symptom improvement, total effective rate, mean duration of treatment, maximum pain score of patients in treatment, patients’ acceptance of treatment methods, and a score of satisfaction with efficacy were also recorded. (2) VAS score was used to evaluate pain: Scored according to patients’ feelings, 0 points indicated painless and 10 points intolerable pain. Each patient was measured in triplicate at 10-minute intervals, and the average value was obtained. (3) ROM score: 1 point indicated free movement, 2 points limited degree and range of motion, 3 points very limited degree and range of motion and stiff and strenuous movement, and 4 points almost unable to move. (4) Score of patients’ acceptance of treatment methods: 2 points indicated acceptance, 1 point reluctant acceptance, and 0 point rejection; Score of satisfaction with efficacy: 2 points indicated satisfaction, 1 point near satisfaction, and 0 point dissatisfaction. (5) Rate of symptom improvement: rate of symptom improvement $>$ 90% was excellent, 60% $<$ rate of symptom improvement $\leqslant$ 90% was good, 30% $<$ rate of symptom improvement $\leqslant$ 60% was ordinary, and rate of symptom improvement $\leqslant$ 30% was poor. Excellent and good rate $=$ (excellent $+$ good)/number of total cases, and effective rate $=$ (excellent $+$ good $+$ ordinary)/number of total cases.

2.7 Statistical analysis

Table 1
Comparison of general information of four groups of patients

Group	$N$	Sex (M/F)	Average age (Y)	Average course of disease (M)
A	50	24/26	53.6 $\pm$ 13.13	33.3 $\pm$ 12.43
B	50	27/23	49.9 $\pm$ 12.34	32.1 $\pm$ 10.14
C	50	22/28	51.6 $\pm$ 10.46	35.4 $\pm$ 15.80
D	50	23/27	52.30 $\pm$ 11.41	34.8 $\pm$ 9.92

Table 2

Comparison of VAS scores of the four groups of patients before and after treatment ( $\bar{x}\pm s$ )

Group	$N$	T0	T1	T2	T3	T4
A	50	5.88 $\pm$ 2.23	5.43 $\pm$ 2.05		4.71 $\pm$ 1.72		4.13 $\pm$ 1.21	${}^{\text{a}}$	5.12 $\pm$ 1.98
B	48	5.91 $\pm$ 1.15	2.91 $\pm$ 0.63	${}^{\text{aeg}}$	4.11 $\pm$ 1.35	${}^{\text{abg}}$	2.90 $\pm$ 1.12	${}^{\text{ace}}$	2.01 $\pm$ 0.88	${}^{\text{abcde}}$
C	47	5.82 $\pm$ 2.05	5.21 $\pm$ 1.55	${}^{\text{f}}$	3.21 $\pm$ 1.08	${}^{\text{abef}}$	2.68 $\pm$ 0.89	${}^{\text{abce}}$	1.81 $\pm$ 0.81	${}^{\text{abcde}}$
D	47	6.02 $\pm$ 1.83	3.51 $\pm$ 1.31	${}^{\text{abeg}}$	2.21 $\pm$ 1.02	${}^{\text{abefg}}$	1.19 $\pm$ 0.56	${}^{\text{abcefg}}$	0.89 $\pm$ 0.33	${}^{\text{abcdefg}}$

Note: Compared with T0, a, $P<$ 0.05; compared with T1, b, $P<$ 0.05; compared with T2, c, $P<$ 0.05; compared with T3, d, $P<$ 0.05; compared with group A, e, $P<$ 0.05; compared with group B, f, $P<$ 0.05; compared with group C, g, $P<$ 0.05.

Statistical analysis was performed using SPSS 23.0. The measurement data are expressed as the mean $\pm$ standard deviation ( $\bar{x}\pm s$ ). The comparison between groups was conducted by one-way ANOVA, the comparison at different time points was performed by ANOVA of repeated measurement data, and the comparison of count data was performed by the $\chi^{2}$ test. $P<$ 0.05 indicated a statistically significant difference.

3. Results

3.1 Comparison of general data and follow-up records of four groups of patients

There was no significant difference in age, sex, or course of disease among the four groups ( $P>$ 0.05) (Table 1).

A total of 192 out of 20 patients were followed up (four patients were transferred due to other diseases, three patients withdrew due to other treatment measures, and one patient withdrew due to job transfer). Two patients in Group B, four in Group C, and three in Group D showed local bleeding at the puncture site, which stopped after pressing for five minutes. Nine patients in Group C had intolerably severe pain and were given an intravenous injection of flurbiprofen axetil 100 mg and completed treatment. Another 17 patients in Group C had severe pain at the puncture site 24 hours after treatment, which affected sleep. They were given oral tramadol 50 mg, and the pain was relieved. There were no other adverse events.

3.2 Comparison of VAS scores of four groups at different time points

Compared with T0, the VAS score was significantly lower in Group A at T3 ( $P<$ 0.05). However, one week after drug withdrawal (T4), the VAS score rebounded, and there was no significant difference compared with T0 ( $P>$ 0.05).

In addition, at T1, compared with Group C, the VAS score was not significantly different in Group A ( $P>$ 0.05). At T2, the VAS score was not significantly different between Groups A and B ( $P>$ 0.05). At other time points, the VAS score was significantly higher in Group A than in the other three groups ( $P<$ 0.05). Compared with T0, VAS scores were significantly lower in Groups B and D at T1 $\sim$ T4 ( $P<$ 0.05), while in Group C, they were not significantly reduced at T1 ( $>$ 0.05) but were significantly reduced at T2 $\sim$ T4 ( $P<$ 0.05). At T1, VAS scores were significantly lower in Groups B and D than in Group C ( $P<$ 0.05), but there was no significant difference between Groups A and C ( $P>$ 0.05). At T2, VAS scores were significantly lower in Groups C and D than in Group B, and they were significantly lower in Group D than in Group C ( $P<$ 0.05). At T4, VAS scores were the lowest in Group D, significantly lower than in Groups B and C ( $P<$ 0.05), and there was no significant difference between the latter two groups ( $P>$ 0.05) (Table 2).

3.3 Comparison of the ROM scores and PPT values of the target MTrPs among the four groups at the last follow-up

Table 3
Comparison of the ROM scores and the PPT values of the target MTrPs among the four groups at the last follow-up ( $\bar{x}\pm s$ )

Group	$N$	ROM (score)			PPT (kg/cm ${}^{2}$ )
		T0	T4	T0	T4
A	50	2.42 $\pm$ 0.73	2.38 $\pm$ 0.46		1.05 $\pm$ 0.32	1.24 $\pm$ 0.43
B	48	2.23 $\pm$ 0.61	1.59 $\pm$ 0.42	${}^{\text{ab}}$	1.16 $\pm$ 0.39	3.01 $\pm$ 1.07	${}^{\text{ab}}$
C	47	2.41 $\pm$ 0.55	1.65 $\pm$ 0.51	${}^{\text{ab}}$	1.09 $\pm$ 0.33	2.97 $\pm$ 0.99	${}^{\text{ab}}$
D	47	2.38 $\pm$ 0.71	1.01 $\pm$ 0.37	${}^{\text{abcd}}$	1.14 $\pm$ 0.37	3.81 $\pm$ 1.25	${}^{\text{abcd}}$

Note: Compared with T0 group, a, $P<$ 0.05; compared with A group, b, $P<$ 0.05; compared with B group, c, $P<$ 0.05; compared with C group, d, $P<$ 0.05.

At T0, there was no significant difference in ROM score or PPT value among the four groups ( $P>$ 0.05). At T4, except for Group A, Rom scores were significantly decreased and PPT values were significantly increased among the three groups compared with T0 ( $P<$ 0.05), and ROM scores among the three groups were significantly lower than in Group A, while PPT value among the three groups was significantly higher than in Group A ( $P<$ 0.05). Among the three groups ROM scores were significantly lower in Group D than in Groups B and C ( $P<$ 0.05). PPT values were significantly higher in Group D than in Groups B and C ( $P<$ 0.05), and there was no significant difference between the latter two groups ( $P>$ 0.05) (Table 3).

3.4 Comparison of the efficacy of the four groups at the last follow-up

Table 4
Comparison of the efficacy of the last follow-up of the four groups of patients [cases (%)]

Group	N	Good rate (%)	Total effective rate (%)
A	50	0 (0) ${}^{\text{bc}}$	8 (16.0) ${}^{\text{bc}}$
B	48	22 (45.8) ${}^{\text{ac}}$	35 (72.9) ${}^{\text{ac}}$
C	47	31 (65.9) ${}^{\text{ab}}$	40 (85.1) ${}^{\text{a}}$
D	47	41 (87.2) ${}^{\text{abc}}$	47 (100.0) ${}^{\text{abc}}$

Note: Compared with group A, a, $P<$ 0.05; compared with group B, b, $P<$ 0.05; compared with group C, c, $P<$ 0.05.

Table 5

Comparison of other indexes of treatment among the three groups of patients ( $\bar{x}\pm s$ )

Group	$N$	Time-consuming treatment (min)	Maximum VAS score during treatment (score)	Treatment plan acceptance score (score)	Efficacy satisfaction score (score)
A	50	–	–	1.61 $\pm$ 0.47	0.21 $\pm$ 0.08
B	48	31.5 $\pm$ 1.1 ${}^{\text{c}}$	1.22 $\pm$ 0.31 ${}^{\text{c}}$	1.72 $\pm$ 0.32 ${}^{\text{c}}$	1.48 $\pm$ 0.32 ${}^{\text{a}}$
C	47	15.3 $\pm$ 4.6 ${}^{\text{b}}$	6.71 $\pm$ 2.14 ${}^{\text{b}}$	0.58 $\pm$ 0.14 ${}^{\text{ab}}$	1.56 $\pm$ 0.25 ${}^{\text{a}}$
D	47	40.4 $\pm$ 12.3 ${}^{\text{bc}}$	2.32 $\pm$ 0.71 ${}^{\text{bc}}$	1.12 $\pm$ 0.30 ${}^{\text{abc}}$	1.61 $\pm$ 0.34 ${}^{\text{a}}$

Note: Compared with group A, a, $P<$ 0.05; compared with group B, b, $P<$ 0.05; compared with group C, c, $P<$ 0.05.

At the last follow-up, the total effective rate in Group A was only 16%, which was significantly lower than that of the other three groups ( $P<$ 0.05). The excellent and good rates and total effective rates were significantly higher in Group D than in Groups B and C ( $P<$ 0.05). The excellent and good rates were significantly higher in Group C than in Group B ( $P<$ 0.05), while the difference in the total effective rate between the two groups was not statistically significant ( $P>$ 0.05) (Table 4).

3.5 Comparison of other indices related to treatment among four groups of patients

The duration of treatment was the longest in Group D, followed by Group B, and the shortest in Group C, with statistically significant differences among the three groups ( $P<$ 0.05). The maximum pain score was the highest in Group C, followed by Group D, and the lowest in Group B, with statistically significant differences among the three groups ( $P<$ 0.05). Group C had the lowest treatment acceptance score ( $P<$ 0.05), followed by Group D, and the scores were similar in Group A and Group C, with no significant difference ( $P>$ 0.05). Group A had the lowest score for satisfaction with efficacy ( $P<$ 0.05), and there was no significant difference in satisfaction with efficacy among the other three groups ( $P>$ 0.05) (Table 5). In addition, the number of MTrPs decreased significantly in Group C after treatment with buccal acupuncture compared to that before treatment ( $P<$ 0.05), with an average difference rate of 69.5 $\pm$ 13.6%.

4. Discussion

The results of this study show that treatment with buccal acupuncture combined with dry needle inactivation of the trigger point for three consecutive weeks can effectively treat chronic cervical and shoulder girdle myofascial pain syndrome.

In modern society, cervical and shoulder girdle myofascial pain syndrome (MPS) has become a very common muscle pain disease in pain clinics [12] and even a frequently occurring disease in young people. There are many ways to treat MPS [5, 6, 7, 13], including massage, laser, low-intermediate frequency electrotherapy, intramuscular patch, muscle stretch and cold spray therapy, shock wave therapy, acupuncture, and inactivation of MTrPs. Recently, Professor Wang Yongzhou and his team applied buccal acupuncture to clinical practice and found that buccal acupuncture had a very good effect on various diseases with pain as the main symptom. The immediate analgesic effect was especially remarkable, with an immediate analgesic rate of up to 72.5%, and buccal acupuncture was effective in persons of yellow, black, and white races [2].

Buccal acupuncture is a novel microneedle technology, and it is theoretically based mainly on the theory of biological holography, the greater triple Jiao theory, and the psychosomatic theory. In therapy with buccal acupuncture, it is believed that there is a miniature holographic system on the cheeks that covers the whole human body [10] (Fig. 1a and b). In this therapy, pain disease is treated by accurately selecting points in corresponding sites based on holographic imaging in combination with exercise therapy. In the clinical application of buccal acupuncture, doctors are required to have a solid knowledge background of traditional Chinese medicine and Western medicine, and before needling, it is necessary to carry out a strict and comprehensive physical examination, as well as abdominal, face, and tongue examinations on patients, and carefully assess the mental state, sleep, urine, and faeces of patients. In the present study, a detailed abdominal examination was performed on patients in Groups B and D before treatment, and it was revealed that most of the patients with chronic cervical and shoulder girdle myofascial pain syndrome had abnormalities distributed in the upper, middle, and lower Jiao, with more abnormalities in the upper Jiao, and there was a large proportion of patients having different degrees of mental and emotional abnormalities, including depression and anxiety, which was consistent with the results of most chronic pain-related studies [14]. In therapy with buccal acupuncture, it is believed that the upper abdomen corresponds to the upper Jiao, the middle abdomen corresponds to the middle Jiao and the lower abdomen corresponds to the lower Jiao, and regulation of triple Jiao can activate the vitality system of the whole body and ensure enduring therapeutic effects. The regulation of triple Jiao works quickly in the treatment of many mental and emotional diseases, and head points are not only used in the treatment of local diseases of the head and face but also important points in the treatment of mental and psychosomatic diseases [10]. In the present study, during treatment with buccal acupuncture for patients with abnormalities in abdominal examination and/or having mental and emotional abnormalities, including depression and anxiety, regulation of triple Jiao was emphasized to eliminate the root cause of disease, and head point needling was added for patients with psychotic symptoms, including insomnia, depression or anxiety.

Clinically, buccal acupuncture is generally performed to treat pain disease, especially pain in the head and face, trunk, and limbs [15, 16]. At present research on the mechanism of acupuncture analgesia focuses on neurobiology theory [17], fasciology theory [18] and local effect theory [19]. On the one hand, acupuncture information goes down to the inhibitory system via the dorsolateral tract and inhibits the nociception of the spinal dorsal horn. On the other hand, acupuncture information goes up to activate different brain nuclei and secrete neurotransmitters (such as 5-HT, NE, ACh, adenosine, etc.) and neuropeptides (such as enkephalin, endorphins, endomorphin, and dynorphin), anti-opioid peptides. Under the action of acupuncture, the growth and decline of these substances in the body determine the existence and strength of acupuncture analgesia. Wang et al. [20] used ovalbumin to induce rheumatoid arthritis in rabbits to observe the analgesic effect of buccal acupuncture. The results showed that the immediate analgesic effect of buccal acupuncture was superior to that of traditional body acupuncture, and this effect was related to changes in B-EP and CCK-8 in the cerebrospinal fluid of model animals, which was one of the mechanisms of central analgesia of buccal acupuncture. Chen et al. [21] used resting brain functional magnetic resonance to study the similarities and differences in activated brain regions in patients with chronic low back pain through the use of balanced acupuncture and traditional body acupuncture. The results showed that compared with traditional body acupuncture, balance acupuncture had a more direct and rapid effect, more obvious analgesia, and a stronger immediate analgesic effect, which was similar to the clinical research results of buccal acupuncture. In a study by Pu et al. [22], it was demonstrated that an obvious analgesic effect occurred at 5 minutes of treatment with buccal acupuncture, and the effect peaked at 30 minutes. Therefore, the needle retention time was 30 minutes in this study, and dry needle inactivation of trigger points was given to patients at the peak of the analgesic effect. The results showed that the combination of these two treatment approaches could not only effectively relieve the pain of dry needle inactivation but also have synergistic or additive effects in the treatment of cervical and shoulder girdle myofascial pain syndrome. Most of the studies on buccal acupuncture are observations of clinical efficacy. For instance, He et al. [23] used buccal acupuncture to treat 90 patients with cervical spondylopathy, with a total effective rate of 95.56%. Chenguang et al. [24] used buccal acupuncture in combination with exercise therapy to treat knee arthritis, with a total effective rate of 98.0%. Ren et al. [25] used buccal acupuncture in combination with exercise therapy to treat an acute lumbar sprain, with a total effective rate of 94.6%. In the present study, treatment with buccal acupuncture alone was given to patients with chronic cervical and shoulder girdle myofascial pain syndrome, with a total effective rate of only 72.9%. However, buccal acupuncture in combination with subsequent dry needle inactivation of myofascial trigger points achieved a total effective rate of 100%. The possible reason for the efficacy difference was that, different from acute pain, the cervical and shoulder girdle myofascial pain in patients in this study had lasted for a long time, approximately 30 months on average, and this chronic pain might have led to or been complicated with other diseases, making treatment of pain complicated. In addition, in most of the studies on buccal acupuncture, efficacy was evaluated immediately after one treatment session or several consecutive treatment sessions (once daily), whereas in the present study, there were a smaller number of treatment sessions (once weekly) and long treatment duration (three weeks in total), and efficacy was finally assessed at one week after the last treatment session (week 4). Therefore, it can be inferred that buccal acupuncture for patients with chronic cervical and shoulder girdle myofascial pain syndrome can not only relieve pain immediately but also show enduring and stable therapeutic effects.

MPS is mainly characterized by the presence of a certain amount of MTrPs in the affected myofascial [26]. Its manifestations are mainly local pain and stiffness of the affected myofascial and pressing or acupuncture on MTrPs can induce local twitch responses (LTRs) as well as referred pain and autonomic nerve phenomena. [27]. To date, there have been no objective and reliable criteria for the diagnosis of MTrPs. At present, MTrPs are mainly detected with the following methods: thumb palpation (during manual pressing, subjects are asked to report tension and pain, which are MTrPs) measurement of the tenderness threshold by a pain metre ultrasound imaging, magnetic resonance elastography (MRE), electromyography (EMG) and thermal texture maps (TTM) [27, 28], with ultrasound imaging being the most commonly used in the diagnosis of MTrPs. It was found in a previous study [11] that MTrPs showed oval, locally heterogeneous hypoechoic or significantly hyperechoic areas in two-dimensional ultrasound imaging. In ultrasound elastography, MTrPs can be displayed in blue or green. In this study, the research group found that nearly 70% of MTrPs showed no obvious tenderness (PPT $>$ 2.5) after 30 minutes of buccal acupuncture treatment, and under elastic ultrasound, it was observed that the elastic coefficient of the tissue in the MTrP area decreased, and the local blue or green changed to red (see Fig. 3i). Most or all symptoms, including local muscle induration and tightness detected by thumb palpation, disappeared, with local muscles relaxed and the patient’s cervical spine mobility increased significantly. It is speculated that nearly 70% of MTrPs may have been inactivated by buccal acupuncture for 30 minutes.

ROM refers to the movement of the cervical spine in three planes: sagittal plane, coronal plane, and horizontal plane. It is a good index to evaluate cervical motor function. At present, ROM can not only be used as a reference to assist in diagnosing certain neck diseases and evaluating the severity of the disease but also to evaluate the treatment effect and prognosis. Researchers believe that the fundamental principle in MPS treatment is that the MTrPs are destroyed based on effective stretching of the involved myofascial [29]. In our experiment, during treatment with buccal acupuncture, active and passive movements of the neck and shoulders of the patients were emphasized to stretch the affected muscles effectively and improve the patient’s POM, which was not only to test the immediate analgesic effect of buccal acupuncture and to adjust or supplement needling [10] but also an important part of MPS treatment. MTrPs are mainly destroyed by dry and wet needles, both of which work by puncturing in different directions repeatedly to destroy or stimulate MTrPs and tension bands, induce LTRs and inactivate the pain sensation of sensory neurons [6]. To avoid the pain caused by repeated puncture of MTrPs, it was recommended to inject a small amount of local anaesthetics as soon as pain occurred during needling [30], and steroid drugs were also recommended for patients with severe lesions [31]. Dry needle inactivation of MTrPs was used in the present study since one of the clinical objective indicators of MTrP inactivation was the disappearance of LTRs induced by acupuncture, and LTRs would not be easily induced if local anaesthetic drugs were given. In addition, side effects of drugs such as intramuscular steroids were also a concern. The results showed that after treatment for three weeks, the pain score decreased significantly, the ROM of the cervical vertebrae improved significantly, the excellent and good rate was 65.9%, and the total effective rate was 85.1%, which was consistent with the results of most studies [29].

In addition, it was observed in our study that the treatment duration was approximately 40 minutes for buccal acupuncture combined with ultrasound-guided inactivation of trigger points, much longer than 15 minutes in Group C. Moreover, it was also observed during clinical treatment that there was a sharp pain in dry needle inactivation of MTrPs, with a VAS score as high as 6.71 $\pm$ 2.14. In the present study, to inactivate MTrPs as thoroughly as possible, it was emphasized to repeatedly puncture MTrPs that could induce LTRs until the aching and swelling pain induced by MTrP puncturing was resolved or significantly reduced and the LTRs disappeared. Consequently, 22.5% of the patients in Group C had to receive additional analgesia (intravenous injection of flurbiprofen axetil) because they could not bear the pain during the treatment. In Group C, the posttreatment pain was also nonnegligible, as the posttreatment aching and swelling pain could last 24 hours in most of the patients and even over 72 hours in some patients. However, the pain in Group B was mostly relieved significantly after 24 hours posttreatment, whereas this complaint was rare in Group D. Therefore, it can be speculated that the posttreatment pain in Group C was attributed to the posttreatment pain after dry needle inactivation of MTrPs, and buccal acupuncture could effectively prevent and treat this pain, with an effect lasting more than 24 hours. Therefore, although the inactivation of trigger points by needling was a traditional method in treating cervical and shoulder girdle myofascial pain syndrome [29], the sharp pain during treatment deterred most of the patients, who showed the lowest acceptance of this treatment regimen. However, except for Group A, there was no significant difference in the degree of satisfaction with therapeutic effect among the other three groups, and the reasons may be that although the excellent and good rate was lower in the group of buccal acupuncture alone, the effective rate was similar to that of the group of dry needle inactivation of trigger points; there was almost no pain in treatment with buccal acupuncture [10], showing high patient comfort; most of the patients with MPS had concomitant mental diseases such as anxiety and depression, but guided by the greater triple Jiao theory and the psychosomatic theory [10], and by reference to the results of the abdominal examination in traditional Chinese medicine, buccal acupuncture regulated triple Jiao specifically in needle arrangement, and patients showed satisfaction with treatment.

The shortcomings of this paper are as follows: 1. The present study was prospective with randomization, but the exposure to the treatment methods jeopardized double blindness. In addition, buccal acupuncture is a novel microneedle technology in traditional Chinese medicine, and the selection of acupoints is largely dependent on the therapists’ experience and preference in diagnosis and treatment. Therefore, this study was not a multicentre comparative study, instead, the treatment of all patients was completed by a chief physician and assessed by a senior nurse, with strict separation between the physician and the assessor. 2. For ethical reasons, this study did not set the sham acupuncture group as the control group, and the basic treatment group was taken as the control group for the comparative study, which may not completely exclude the placebo effect. It was reported that [32] the therapeutic effect of acupuncture and moxibustion for analgesia persisted with time, which was not explained by the placebo effect. Combined with the results of this study, it was found that one week after the last treatment of buccal acupuncture, the analgesic effect, and improvement of cervical motion of patients were still continuous and stable, which may exclude the influence of the placebo effect to a certain extent.

5. Conclusions

Buccal acupuncture combined with dry needle inactivation of trigger points is safe, highly effective, and slightly painful and shows a high degree of patient acceptance and satisfaction in the treatment of cervical and shoulder girdle myofascial pain syndrome; hence, it is a good choice in treating this syndrome and worthy of popularizing in clinical practice.

Ethics statement

This study was approved by the Ethics Committee of the First Affiliated Hospital of Suzhou University.

Data availability statement

The data used to support the findings of this study are available from the corresponding author upon reasonable request.

Informed consent

Not applicable.

Author contributions

HHS, FHC, HYN, SLL, XHL and XJG participated in the study design, analyzed the data, and wrote this report. XMZ, SLL and XLC prepared experimental materials and carried out the experiments. All authors read and approved the final manuscript.

Funding

This study was financially supported by the Beijing Medical Award Foundation (YXJL-2021-1271-0655), the fifth "333 high-level talent training project" scientific research project fund of Jiangsu Province (BAR2018261) and the Suzhou integrated traditional Chinese and Western medicine project (SYSD2019206).

Footnotes

Acknowledgments

The authors thank the First Affiliated Hospital of Suzhou University.

Conflict of interest

The authors declare that they have no competing interests.

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Buccal acupuncture combined with ultrasound-guided dry needle-evoked inactivation of trigger points to treat cervical and shoulder girdle myofascial pain syndrome

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Materials and methods

2.1 General materials

2.2 Exclusion criteria

2.3 Treatment methods

2.6 Outcome measures

2.7 Statistical analysis

Table 1 Comparison of general information of four groups of patients

3.1 Comparison of general data and follow-up records of four groups of patients

3.2 Comparison of VAS scores of four groups at different time points

3.3 Comparison of the ROM scores and PPT values of the target MTrPs among the four groups at the last follow-up

Table 3 Comparison of the ROM scores and the PPT values of the target MTrPs among the four groups at the last follow-up ( x ¯ ± s )

Table 4 Comparison of the efficacy of the last follow-up of the four groups of patients [cases (%)]

4. Discussion

5. Conclusions

Ethics statement

Data availability statement

Informed consent

Author contributions

Funding

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Comparison of general information of four groups of patients

Table 3
Comparison of the ROM scores and the PPT values of the target MTrPs among the four groups at the last follow-up ( $\bar{x}\pm s$ )

Table 4
Comparison of the efficacy of the last follow-up of the four groups of patients [cases (%)]