The analgesic and disability improvement effects of trigger points electroacupuncture on chronic low back pain patients: an uncontrolled before-and-after study

An uncontrolled before-and-after study was performed on 37 University of Medical Center Ho Chi Minh City – Branch no. 3 patients from February 2021 to February 2023.

Inclusion criteria: (1) patients aged 45 or older who consented to participate in the study; (2) individuals experiencing LBP persisting for more than 3 months with an average VAS score of 5 cm or over; (3) patients displaying trigger points in back and legs; (4) Additional criteria could include symptoms such as pain, numbness down the legs.

Exclusion criteria: (1) major trauma or systemic disease such as rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, Scheuermann disease; (2) systemic symptoms such as weight loss, fever of unknown origin, anorexia, personal history of malignancy, diffuse pain and joint stiffness; (3) symptoms of infection such as fever, meningeal irritation signs, photophobia; (4) symptoms of central motor neuron damage such as Hoffmann sign, Babinski sign, hyperreflexia, spasticity, incontinence, sexual dysfunction; (5) symptoms of serious acute diseases such as myocardial infarction (chest pain, sweating, shortness of breath), arterial dissections (tearing sensation, headache, blurred vision); (6) Conditions unsuitable for acupuncture such as inflammation of skin in need of acupuncture, weak or exhausted patients, severe comorbidities; (7) being treated with other methods.

Elimination criteria: (1) patients experiencing adverse events from the intervention leading to their discomfort and withdrawal from the study; (2) patients with unfavorable comorbidities necessitating alternative treatment approaches during the study period; (3) individuals not experiencing pain relief after three days of treatment (shifted to the hospital’s treatment plan); (4) patients failing to adhere to the study’s treatment regimen, discontinuing the intervention more than twice.

Using convenience sampling, all patients with chronic LBP at the University of Medical Center Ho Chi Minh City – Branch no. 3 would be invited to participate in the study. Among these patients, those who met the inclusion criteria would receive the intervention. All patients were treated at trigger points following the International Consensus on Diagnostic Criteria and Clinical Considerations of Myofascial Trigger Points in 2018. The diagnosis of trigger points is confirmed when at least 2 of the following criteria are present: (1) A taut band: The investigator presses gently along the muscle fibers, feeling a small nodule at trigger points and a fibrous band like a rope extending from this nodule to the distal attachment of the stretched muscle fibers; (2) A hypersensitive spot: The investigator presses along the stretched muscle band would reveal a small nodule with a well-localized characteristic and very painful to press; (3) Referred pain: Referred pain is pain that begins at trigger points and spreads to other positions [5]. Qualified patients were treated with TrP-EA at 100 Hz for 4 weeks. Electroacupuncture was performed once a day and 5 days per week (taking Saturday and Sunday off each week) continuously for 4 weeks, the duration of electroacupuncture is 20 minutes in each session. Acupuncture needles (disposable acupuncture needles 0.30×25 mm, Khanh Phong brand, Vietnam) were inserted into the skin at a depth of 1.5–4 cm. Acupuncture was manipulated by traditional medicine doctors who have practicing certificates. The acupuncturist stimulated the needles until the patients reached a feeling of ‘de qi’ sensation (the patients felt moderately tense, heavy, and painless in the areas where acupuncture needles were inserted) and then stimulated points with an electrical acupuncture device. The frequency was adjusted to 100 Hz and the intensity was gradually increased from 1 to 100 µA (depending on the patient’s tolerance level).

In addition to TrP-EA, patients were guided to engage in self-care practices, maintain proper posture, and perform active lumbar spine mobility exercises during the first week. Over the following 3 weeks, patients continued active lumbar movement exercises at the hospital once a week, under the supervision of researchers, and performed these exercises at home for the remainder of the time. These exercises comprised various activities, including lumbar spine range of movement exercises, lumbar muscle stretching exercises, lumbar muscle strength training, and muscle relaxation. Each exercise session lasted for 15 minutes, performed twice daily, continuously for 4 weeks.

Furthermore, the researchers emphasized the importance of avoiding poor posture during daily activities, such as bending over, lifting heavy objects, and making sudden movements, to prevent direct trauma to the lower back.

VAS is a 10 cm long horizontal line, the two ends of which are depicted corresponding to the two extremes of pain: the left end (0 cm) of the scale is “no pain” and the right end of the scale (10 cm) is “worst imaginable pain”. Patients were required to manually position their pain intensity over the past 24 hours on VAS. The distance (mm) from where the patient locates to 0 is the VAS point [6].

RMQ consists of 24 questions covering limitations of daily activities due to LBP such as walking, caring for someone, sitting, lying down, dressing, sleeping, self-care, and daily living. Each item is 1 point, score ranges from 0 points (no disability) to 24 points (max disability). RMQ is also used to assess clinical improvement as a percentage based on score reduction after treatment [7].

ODI has 10 sections that deal with the daily activities of life disrupted by LBP. Each item is answered on a Likert scale from 0 (no problem at all) to 5 (not possible). The total score ranges from 0 to 50 [8].

VAS, RMQ, and ODI were assessed at the time of pre-treatment, after 1 week, 2 weeks, 3 weeks, and 4 weeks of treatment.

Adverse events were assessed throughout the study including pain, swellings, bleeding, infection at the needle positions, nausea, dizziness, cold sweat, cold hands and feet, and low blood pressure.

Data were imported and managed by Microsoft Excel. Statistical analysis was performed by R version 4.3.1. The qualitative data were reported as frequency with a percentage (%). The quantitative data were reported as mean with SD and 95% confidence of interval for mean (95%CI). When the quantitative variables were normally distributed, one-way ANOVA was used to compare the difference between mean values from the baseline to the fourth week of treatment. If the F-ratio in ANOVA was statistically significant, Turkey HSD test would be used to compare between each week and the previous consecutive week. When the quantitative variables were not normally distributed, we applied logarithmic transformation to normalize the distribution. If the normalizing transformation was unsuccessful, Kruskal-wallis test and Dunn-Bonferroni test would be used instead. The difference was statistically significant when p<0.05.

From February 2021 to February 2023, a total of 37 participants were recruited. There were no missing data in 37 participants, none of the participants withdrew due to adverse events. The baseline features of the patients are presented in Table 1. Participants in the study ranged in age from 45 to 86 years old, the average age was 59.78±11.15 years. Males accounted for 43.24% and females accounted for 56.76%. The average number of trigger points (corresponding to the number of needles) was 5.51±1.02, the minimum number of trigger points was 4 and the maximum was 7.

According to Table 2 and Fig. 1, the results show that the VAS, RMQ, and ODI scores decreased dramatically after 1 week of treatment and continued decreasing after every week during the intervention (all p<0.01). The lowest VAS, RMQ, and ODI scores were recorded after the last treatment session. Specifically, after 4 weeks of treatment, the VAS score was reduced from 6.22±0.92 (95%CI: 5.91–6.52) mm at baseline to 1.51±0.99 (95%CI: 1.18–1.84) mm, the RMQ score was reduced from 8.81±1.51 (95%CI: 8.31–9.31) points at baseline to 1.92±1.16 (95%CI: 1.53–2.31) points and the ODI score decreased from 14.65±2.89 (95%CI: 13.69–15.61) points at baseline to 5.97±2.18 (95%CI: 5.25–6.70) points. All indices of VAS, RMQ, and ODI showed a statistically significant decrease even when comparing each week with the previous consecutive week.

Fig. 1. VAS, RMQ and ODI scores after each week of the intervention. VAS, visual analogue scale; RMQ, roland morris questionnaire; ODI, Oswestry low back pain disability index.

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The results showed that the average improvement percentage after 1 week of treatment was 21.71±10.77 (%) and continued to increase after each week for the next three weeks. The average improvement percentage after 2 weeks, 3 weeks, and 4 weeks of treatment was statistically significantly different from the time after 1 week of treatment (p<0.01). This index also showed a statistically significant increase even when comparing each week with the previous consecutive week (Table 3).

During the study, 3 (8.00%) patients experienced slight bleeding at the needle positions. However, the bleeding was minor and ceased immediately upon the application of sterile cotton to the needle positions. No other adverse events (pain, swellings, infection at the needle positions, nausea, dizziness, cold sweat, cold hands, and feet, low blood pressure, etc.) occurred during the intervention period. None of the participants discontinued due to adverse events (Table 4).

Compared with the pre-treatment baseline, the study results showed a statistically significant decrease in VAS score right after one week of treatment, and this score continued to decrease significantly each week during 4 weeks of intervention. The VAS score achieved the lowest index at the final assessment time (after 4 weeks of treatment). These results supported the hypothesis that 100 Hz TrP-EA can reduce pain in patients with chronic LBP. With the aim of pain relief in patients with moderate chronic LBP, this evidence suggests that each course of TrP-EA should last at least 4 weeks to achieve optimal pain relief.

Our study results are consistent with previous studies on trigger points acupuncture: Research by Kazunori Itoh and his partners shows that trigger points acupuncture has better pain relief than standard acupuncture [2]; research by Emİne Handan Tüzü and research by Mario Téllez-García showed that trigger points acupuncture helps to reduce pain, the number of trigger points, the sensitivity of the trigger points in patients with LPB [9],[10]. Our study, with a larger sample size and comparable assessment tools, strengthens the claim regarding the pain-relieving impact of trigger points acupuncture. A novel aspect of our study is the incorporation of electroacupuncture at a frequency of 100 Hz during trigger point acupuncture. However, our study design has no manual acupuncture group, so we could not compare the analgesic effect between manual acupuncture and electroacupuncture at trigger points.

Compared with the pre-treatment baseline, the study results showed a statistically significant decrease in RMQ and ODI scores each week during 4 weeks of treatment. These scores achieved the lowest index after four weeks of treatment. During 4 weeks of treatment, the RMQ and ODI scores between 2 consecutive weeks of treatment were also significantly different. These results supported the hypothesis that TrP-EA at 100 Hz may effectively improve disability in patients with LBP. Because RMQ and ODI have different sensitivities depending on the patient’s disability, using both these questionnaires in the study could increase the accuracy of the disability assessment in patients with chronic LBP, thereby increasing the reliability of the study [11].

Compared with previous studies, our study results are consistent with Kazinori Itoh’s and Mario Téllez-García’s study on the improving disability effect of trigger points acupuncture [2],[10]. However, in our study, patients were also taught self-care, correct posture, and active lumbar spine exercises, so the improving disability effect of TrP-EA is still unclear. Our study results can be the basis for conducting new studies in the future to confirm more clearly the improving disability effect of TrP-EA.

One of the differences between RMQ and ODI is that RMQ does not categorize disability. However, RMQ can estimate the rehabilitation effect of a treatment as a percentage through the reduction in RMQ score after treatment. The study results showed that the improvement percentage after 2 weeks of treatment was over 40% and significantly increased compared with 1 week before. The improvement percentage was over 50% after 3 weeks of treatment and over 70% after 4 weeks of treatment. This index was also significantly different between 2 consecutive weeks during four weeks of treatment. These results show that TrP-EA at 100 Hz is the method that brings relatively high rehabilitation efficiency in the treatment of chronic LBP.

The study results showed that the number of trigger points on the objects of the study was 5.51±1.02. It means that each patient may only need to acupuncture 5 to 6 points in each session to achieve relatively high therapeutic effects. The number of needles for TrP-EA is less than standard acupuncture (acupuncture in 9 points), which is the advantage of TrP-EA [2].

Our study did not have the control group treated with the standard acupuncture, so we could not compare the treatment effect between this method and TrP-EA. Further randomized controlled clinical trial studies are needed to be performed to investigate other advantages of electroacupuncture at trigger points.

The results showed that there were 3 (8.00%) cases of bleeding at the needle positions, but these cases only had slight bleeding and stopped bleeding immediately after using sterile cotton to press the needle positions. This result is consistent with previous studies on the adverse events of acupuncture: The studies of Witt Claudia M in 2009, Enblom Anna in 2017, Wang Carol C in 2019, etc. These authors concluded that most of the adverse events of acupuncture were mild [12]–[14]. In addition, we did not record any other adverse effects during the study. These results help to confirm that TrP-EA is a relatively safe treatment method.

With larger sample sizes than previous studies, our results confirm more strongly the positive effect on pain relief of trigger points acupuncture in patients with chronic LBP. The novelty of our study is the addition of 100 Hz electroacupuncture in trigger points acupuncture. The research shows that this is a potential treatment to help patients with chronic LBP shorten treatment time and reduce the use of pain relievers. We compared the results between 2 consecutive weeks, which helps prognosis treatment time in patients with chronic LBP. In addition, we used both RMQ and ODI in the study, which helps to increase the accuracy of the disability assessment in patients with chronic LBP and can also assess the improvement percentage of TrP-EA at 100 Hz.

The limitation of our study is having no control group to compare the therapeutic effect of 100 Hz electroacupuncture at trigger points with manual acupuncture at these points. Besides, this study applied convenience sampling, so the results have reduced reliability in reflecting treatment effectiveness in the general population. In addition to 100 Hz TrP-EA, patients in our study were also taught self-care, correct posture, and active lumbar spine exercises. For this reason, the improving disability effect of this treatment still has not been demonstrated clearly. Another drawback of our study is that the survey only lasted 4 weeks after the intervention, so our study did not evaluate the pain relief and improving disability effectiveness of the method from 5 weeks onwards after the intervention, as well as the duration of effect maintenance after stopping the intervention. However, our study results can be the basis for randomized controlled trial studies in the future to assert the efficacy of TrP-EA more strongly.