Effects of interferential therapy parameter combinations upon experimentally induced pain in pain-free participants: a randomized controlled trial

The effect of transcutaneous electrical nerve stimulation on pain and electrical stimulation muscle thickness in patients with non-specific chronic low back pain-based ultrasonographic evaluation

Aim: The existing mechanisms of transcutaneous electrical nerve stimulation (TENS) focuses more on the effect of neural tissue. This study investigated the effect of TENS on the thickness of the erector spinae muscles and reducing pain. Patients & methods: 56 individuals with low back pain participated in this single-blind, pre/post-test study. For 2 weeks, participants underwent ten sessions of TENS. The ultrasound evaluations examined the thickness of the erector spinae muscle, and the visual analog scale measured the severity of low back pain. Results: There was a decrease in pain score and muscle thickness after the interventions (p ≤ 0.004). There was also a strong correlation between reducing pain and decreasing muscle thickness (R = 0.709; p = 0.000). Conclusion: Following TENS in the lumbar, in addition to reducing pain, the thickness of the erector spinae muscles also decreased. Clinical Trial Registration: IRCT20200423047173N1 (ClinicalTrials.gov).

Effect of premodulated interferential current versus diadynamic current on the management of lateral elbow tendinopathy

Study aim: To compare the effect of premodulated interferential current (PREMOD IFC) and diadynamic current (DD) with exercise training on the management of lateral elbow tendinopathy (LET).

Material and methods: One hundred and four patients with unilateral LET from both genders (55 females and 49 males) were randomly allocated into two groups. Group A received PREMOD IFC in addition to the exercises, and group B received DD with the same exercises. The outcomes were maximum grip strength assessed by the hand dynamometer, the pinch strength assessed by the pinch gauge dynamometer, and pain and functional disability of the forearm assessed by a patient-rated tennis elbow evaluation (PRTEE) questionnaire. All participants received electrical stimulation, consisting of three sessions per week for six weeks.

Results: The mean PRTEE score, and grip strength were significantly improved after six weeks in favour of group A, while there was no significant difference between the two groups in pinch strength. (p < 0.05).

Conclusion: The results revealed that the combination of PREMOD IFC with exercises could improve pain, functional disability, and grip strength compared to DD with exercises in LET patients without a significant difference between the two groups in pinch strength.

Efficacy of Transcutaneous Electrical Nerve Stimulation and Interferential Current on Tactile Acuity of Individuals With Nonspecific Chronic Low Back Pain

OBJECTIVES

Transcutaneous electrical nerve stimulation (TENS) and interferential currents (IFC) are pain electrotherapies with questioned efficacy. Studies of their effects on tactile acuity of individuals with nonspecific chronic low back pain (NSCLBP) are limited, hence, this study.

MATERIALS AND METHODS

Thirty-three individuals with NSCLBP randomly allocated into three groups completed this study. Data collected from participants included age, gender, and anthropometric characteristics of height, weight, body mass index, and percentage body fat measured with standard instruments. Also, participants' tactile acuity, pain intensity, and disability were assessed before and after interventions with digital caliper, numerical pain rating scale, and Roland-Morris Disability Questionnaire, respectively. Interventions consisted of stretching, strengthening, and stabilization exercises to all three groups in addition of TENS to group 1 and IFC to group 2, respectively, for five weeks. Descriptive statistics of mean and standard deviation summarized the data. Inferential statistics of paired t-test, independent t-test, and analysis of variance tested the level of significance among variables at p ≤ 0.05.

RESULTS

Tactile acuity was significantly (p < 0.05) increased after TENS intervention only, while pain intensity was significantly (p < 0.05) reduced after the three interventions. The result showed no gender difference in tactile acuity values among the participants.

CONCLUSIONS

TENS increases the tactile acuity of individuals with NSCLBP, whereas IFC demonstrated no significant change in tactile acuity.

Analgesic Effects of Interferential Current Therapy: A Narrative Review

Background and Objectives: Transcutaneous electrical stimulation of low- and medium-frequency currents is commonly used in pain management. Interferential current (IFC) therapy, a medium frequency alternating current therapy that reportedly reduces skin impedance, can reach deeper tissues. IFC therapy can provide several different treatment possibilities by adjusting its parameters (carrier frequency, amplitudemodulated frequency, sweep frequency, sweep mode or swing pattern, type of application (bipolar or quadripolar), time of application and intensity). The objective of this review article is to discuss the literature findings on the analgesic efficacy of IFC therapy. Conclusions: According to the literature, IFC therapy shows significant analgesic effects in patients with neck pain, low back pain, knee osteoarthritis and post-operative knee pain. Most of the IFC parameters seem not to influence its analgesic effects. We encourage further studies to investigate the mechanism of action of IFC therapy.

Immediate Effects of the Combination of Interferential Therapy Parameters on Chronic Low Back Pain: A Randomized Controlled Trial

OBJECTIVES

To compare the immediate analgesic effects of 2 kHz or 4 kHz interferential current (IFC) with different amplitude-modulated frequencies (AMFs) (2 Hz or 100 Hz) on chronic low back pain (CLBP).

DESIGN

Three-arm double-blinded randomized controlled trial.

SETTING

Primary care.

PARTICIPANTS

175 patients (19 to 60 years of age, 105 female) with CLBP.

INTERVENTIONS

One session of IFC: Interferential group (GI): GI2 kHz/100 Hz, GI2 kHz/2 Hz, GI4  kHz/100 Hz, GI4 kHz/2 Hz, or placebo.

MAIN OUTCOMES MEASURES

Pain intensity by numerical rating scale of pain (NRS), McGill Pain Questionnaire (MPQ), and algometry.

RESULTS

There was a significant difference in NRS scores (P < 0.05) in the GI2 kHz/2 Hz, GI4 kHz/2 Hz, and GI4 kHz/100 Hz groups compared with those of the placebo group (PG), and a significant difference in MPQ scores in the GI4 kHz/2 Hz and GI4 kHz/100 Hz groups compared with those of the PG. In algometry, only the GI4 kHz/100 Hz group showed a significant difference (by 2 points in the lumbar region) compared with the PG. Of the carrier frequencies, an IFC of 4 kHz showed more effective results, although no significant difference was noted between the AMFs.

CONCLUSION

An IFC with a carrier frequency of 4 kHz and an AMF of 100 Hz provide immediate analgesic effects in individuals with CLBP.

CLINICAL TRIAL REGISTRATION NUMBER

RBR-59YGRB.

Validation of a New Placebo Interferential Current Method: A New Placebo Method of Electrostimulation

Objective

The present study aimed to investigate if a new placebo device for interferential current (IFC) that delivers current during only the first 40 seconds of stimulation is effective at promoting adequate subject blinding.

Methods

Seventy-five subjects were recruited and enrolled into three groups: active IFC, inactive placebo, and new placebo. Pressure pain threshold (PPT), cutaneous sensory threshold (CST), and pain intensity were measured before and after the intervention. After the final assessment, the subjects and the investigator who applied the current were asked about the type of stimulation administered.

Results

None of the placebo forms studied resulted in significant changes to PPT, CST, or pain intensity. The subjects stimulated with active IFC at high intensities (> 17 mA) of stimulation showed higher PPT and CST and lower pain intensity than subjects stimulated at low intensities ( p < 0.03). The new placebo method blinded the investigator in 100% of cases of IFC and 60% of subjects stimulated, whereas for inactive placebo, the investigator was blinded at a rate of 0% and 34% of subjects.

Conclusion

The new method of placebo IFC was effective for blinding of research investigators and most of the active IFC-treated subjects, promoting an appropriate placebo method.

Effect of interferential current therapy on pain perception and disability level in subjects with chronic low back pain: a randomized controlled trial

Objective:

To assess the short-term efficacy of transregional interferential current therapy on pain perception and disability level in chronic non-specific low back pain.

Design:

A randomized, single-blinded (the assessor collecting the outcome data was blinded), controlled trial.

Setting:

A private physiotherapy research clinic.

Subjects:

A total of 64 individuals, 20 men and 44 women, mean (SD) age was 51 years (11.93), with low back pain of more than three months, with or without pain radiating to the lower extremities above the knee, were distributed into a control ( n = 20) or an experimental group ( n = 44). A 2:1 randomization ratio was used in favour of the latter.

Interventions:

A transregional interferential current electrotherapy protocol was performed for participants in the experimental group, while the control group underwent a ‘usual care’ treatment (massage, mobilization and soft-tissue techniques). All subjects received up to 10 treatment sessions of 25 minutes over a two-week period, and completed the intervention and follow-up evaluations.

Outcome measures:

Self-perceived pain was assessed with a Visual Analogue Scale. Secondary measure included the Oswestry Low Back Disability Index. Evaluations were collected at baseline and after the intervention protocol.

Results:

Significant between-group differences were found for interferential current therapy on pain perception ( p = 0.032) and disability level ( p = 0.002). The observed differences in the between-group mean changes were of 11.34 mm (1.77/20.91) and 13.38 points (4.97/21.78), respectively.

Conclusions:

A two-week transregional interferential current treatment has shown significant short-term efficacy, when compared with a ‘usual care’ protocol, on self-perceived pain and functionality in subjects with chronic low back pain.

Effects of the carrier frequency of interferential current on pain modulation in patients with chronic nonspecific low back pain: a protocol of a randomised controlled trial

BACKGROUND

Low back pain is an important public health problem that is associated with poor quality of life and disability. Among the electrophysical treatments, interferential current (IFC) has not been studied in patients with low back pain in a high-quality randomised controlled trial examining not only pain, but pain mechanisms and function.

METHODS/DESIGN

A three-arm randomised controlled trial with patient and assessor blinded to the group allocation. One hundred fifty patients with chronic, nonspecific low back pain from outpatient physical therapy clinics in Brazil. The patients will be randomly allocated into 3 groups (IFC 1 kHz, IFC 4 kHz or Placebo IFC). The interferential current will be applied three days per week (30 minutes per session) over four weeks.

PRIMARY OUTCOME

Pain intensity.

SECONDARY OUTCOMES

The pressure pain threshold, global impression of recovery, disability, function, conditioned pain modulation and temporal summation of pain, discomfort caused by the current. All outcomes will be measured at 4 weeks and 4 months after randomisation. The between-group differences will be calculated by using linear mixed models and Tukey's post-hoc tests.

DISCUSSION

The use of a placebo group and double-blinding assessor and patients strengthen this study. The present study is the first to compare different IFC carrier frequencies in patients with chronic low back pain.

TRIAL REGISTRATION

Brazilian Registry of Clinical Trials: http://RBR-8n4hg2.