Effect of Adjuvant Frequency Specific Microcurrents on Pain and Disability in Patients Treated with Physical Rehabilitation for Neck and Low Back Pain

Gautam M. Shetty, Pallavi Rawat, Anjali Sharma

Originally published in: Journal of Bodywork & Movement Therapies, Volume 24 (2020), Pages 168-175

QI Spine Clinic, Mumbai and Pune, India

Abstract

Objectives: To evaluate the efficacy of adjuvant frequency-specific microcurrent (FSM) application on pain and disability in patients treated with physical rehabilitation for mechanical low back pain (LBP) and neck pain (NP).

Methods: In this retrospective case-control study, pre- and post-treatment numerical pain rating scale (NPRS) score, Oswestry disability index (ODI) score, neck disability index (NDI) score, disability categories, and treatment outcome categories were compared between 213 patients in the FSM group (167 patients with LBP, 46 patients with NP) and 78 patients in the control group (61 patients with LBP, 17 patients with NP).

Results: In LBP patients, mean post-treatment NPRS score was significantly lower (p = 0.02) and a significantly higher percentage of patients were in the ≤3 NPRS score (p = 0.02), in the minimal disability (p = 0.01), and the full success (p = 0.006) categories post-treatment in the FSM group when compared to the control group. In NP patients, there was no significant difference in the post-treatment pain intensity, disability or treatment outcome when the 2 groups were compared.

Conclusions: The use of adjuvant FSM application in patients treated with physical rehabilitation for LBP significantly improved pain and disability when compared to patients in the control group. Frequency specific microcurrent could be a useful adjuvant in the rehabilitation treatment of patients with low back pain.

Introduction

Electrophysical modalities such as transcutaneous electrical nerve stimulation (TENS), interferential current stimulation, diadynamic current stimulation, and high-voltage electrical stimulation are used for pain management in patients with musculoskeletal conditions. However, the evidence is lacking in the literature about the efficacy of such modalities on acute or chronic low back pain (LBP) or neck pain (NP). A recent systematic review and meta-analysis reported inconclusive evidence of benefits of TENS in patients with low back pain patients due to the low quality of studies available in the literature. However, another systematic review which analyzed 700 patients, reported that although TENS does not improve symptoms of lower back pain, it may offer short-term improvement of functional disability.

Frequency-Specific Microcurrent (FSM)

Frequency-specific microcurrent (FSM) is an electrophysical modality used in pain management that delivers very low-intensity electric current to tissues within the microampere (μA) range, approximately 1000 times lower than the current intensity used in TENS. Microcurrent application is based on the principle that a current closer to the cellular current of the body can overcome electrical resistance of injured or inflamed tissue, restore cellular homeostasis, and facilitate tissue regeneration in contrast to TENS which primarily works by blocking the transmission of pain signals.

Although the mechanism of action of FSM is not yet clear, these microcurrents of physiological amperage when delivered to damaged or inflamed tissues is said to alter cell membrane function, reduce inflammation, and promote healing by maintaining intracellular Ca2+ homeostasis and upregulating ATP production.

Previous Research

Although previous studies have reported the efficacy of microcurrent in improving muscle function in musculoskeletal conditions such as delayed onset muscle soreness, congenital muscular torticollis, spastic myocontracture in cerebral palsy, and age-related muscle weakness, literature is lacking on the effect of FSM application on pain and disability in patients with LBP or NP. Hence, this study aimed to determine the efficacy of adjuvant FSM application on pain and disability in patients treated with physical rehabilitation for LBP and NP. We hypothesized that the use of adjuvant FSM application in patients treated with physical rehabilitation for LBP and NP will significantly improve pain and disability when compared to patients where FSM is not used.

Patients and Methods

Study Design

In this retrospective analysis, electronic records of routinely collected data from all patients treated for low back pain (LBP) and neck pain (NP) at 3 outpatient clinics specializing in spine rehabilitation (QI Spine Clinic, Pune) from October 2016 to January 2019 were analyzed.

Inclusion Criteria:

• All patients with LBP or NP
• More than 20 years of age
• Underwent physical rehabilitation treatment at the clinics

Exclusion Criteria:

• Patients with inflammatory conditions such as rheumatoid arthritis and spondyloarthropathies
• Patients where peripheral joints such as hip, knee and ankle joints were involved
• Patients with structural kyphotic or scoliotic deformities
• Patients with peripheral neuropathy
• Patients with complex regional pain syndrome (CRPS)
• Patients with lumbar canal stenosis (LCS)
• Patients who did physiotherapy for less than 1 month or more than 3 months at the centre

Study Population

Based on the inclusion criteria, 1187 patients who underwent treatment for LBP and NP at the outpatient clinics were eligible to be part of this study. Among the eligible patients, 811 patients received adjuvant FSM therapy (FSM group) whereas 376 patients did not receive the adjuvant FSM therapy (control group) during their treatment for LBP or NP.

After applying exclusion criteria, data from 213 patients in the FSM group and data from 78 patients in the control group were analyzed and compared for this study. This study was approved by an Institutional Ethics Committee and was performed as per the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

Outcome Measures

All patients were evaluated clinically before and during treatment for their LBP or NP. A thorough history of presenting complaints, past illness, previous surgical or non-surgical treatment or any red flag conditions (recent trauma, night or at rest pain, fever, unexplained weight loss, progressive motor or sensory deficit, bowel or bladder symptoms, history of cancer, chronic steroid use, and immunosuppression) was recorded.

All patients were clinically examined for posture, lumbar spine movement, motor and sensory function (myotomal and dermatomal loss) by a physiotherapist in the clinic. The intensity of LBP or NP was recorded using the numerical pain rating scale (NPRS) with pain intensity ranging from “0” (no pain) to “10” (worst pain imaginable) and functional disability was recorded using the Oswestry disability index (ODI) or Neck disability index (NDI) before and after treatment.

Using the Mechanical Diagnosis and Therapy (MDT) system, all patients were evaluated by movement testing and diagnosed as reducible derangement, irreducible derangement, postural syndrome, dysfunction syndrome, or others by a senior physiotherapist in the clinic.

Treatment Protocol

A multimodal, active rehabilitation protocol involving a combination of patient education, pain management using directional movements with or without application of frequency-specific microcurrents (FSM), and strength and stabilization exercises was administered to all patients in an outpatient clinic. Rehabilitation protocol was varied and personalized based on the severity of pain on NPRS and response to movement testing.

All patients, during the first consultation, were educated about and recommended application of FSM as an adjuvant to physical therapy to improve pain and function, especially when the NPRS score was >3 by the consulting physiotherapist. However, the decision to use FSM application was left to the patient.

Treatment Protocol by Pain Level:

NPRS ≥7: Patients were advised light extension/flexion mobilization exercises for muscle activation, maintaining proper posture and rest (breaking posture and going to a non-loading position like lying supine) when required during activities of daily living for a maximum of 1 week. Patients who opted for FSM therapy were administered FSM as a 30-min session, every day during the first 1 week of treatment.

NPRS 4-7: Movement testing was done using the MDT method to determine directional preference. Patients were then advised directional movements that were performed under supervision by the treating physiotherapist and advised to be continued at home at frequent intervals. Patients were reviewed every week for progress or improvement in pain and function.

NPRS <4: Paraspinal muscle strengthening and stabilization exercises were administered.

All patients underwent a minimum rehabilitation treatment of 30 days and a maximum of 90 days. A minimum of 6 supervised physiotherapy sessions at the clinic was advised to all patients. Post-treatment clinical assessment was performed at the time of discharge to determine NPRS score, ODI/NDI score and disability category.

Treatment Outcome Categories

Treatment outcome was considered:

• Full success: Patient shifted to a disability category of “minimal” and had pain improvement on NPRS of >80%
• Partial success: Patient improved in disability by one category (e.g., a shift from severe to moderate category) and pain improvement on NPRS of 30%-80%
• Failure: Patients did not fall into the full or partial success category at the end of treatment

Statistical Analysis

Pre-treatment baseline parameters such as gender ratio, age, lifestyle, history of night pain, response of pain to movement testing, anatomical case type, treatment sessions done and total treatment period were analyzed. Clinical outcome parameters such as NPRS score, ODI/NDI score, change in disability category and treatment outcome category were compared before and after treatment between the FSM and control groups to determine the effectiveness of adjuvant FSM therapy.

The Fisher’s test or Chi-square with Yates’ was used to compare categorical data whereas the t-Test was used to compare continuous data within and between the 2 groups. Statistical significance was accepted for p values less than 0.05 in all tests. Statistical analysis was performed using the SPSS (ver. 20.0) statistical analysis software.

Results

Baseline Characteristics

The baseline characteristics of the 213 patients in the FSM group and 78 patients in the control group showed no significant differences:

• Mean age: FSM group 48.5 ± 14.8 years vs Control group 45.7 ± 14.8 years (p = 0.15)
• Mean BMI: FSM group 25.8 ± 3.8 kg/m² vs Control group 25.9 ± 3.4 kg/m² (p = 0.83)
• Gender ratio: FSM group 66.5% males vs Control group 64% males (p = 0.88)
• Case type: FSM group 78.5% LBP vs Control group 78% LBP (p = 1.00)
• Lifestyle: Sedentary lifestyle FSM group 75% vs Control group 69% (p = 0.43)
• Night pain: FSM group 47.5% vs Control group 45% (p = 0.88)
• Mean treatment sessions: FSM group 16 ± 6.2 vs Control group 16 ± 6.5 (p = 1.00)
• Mean treatment period: FSM group 56.6 ± 16.8 days vs Control group 57 ± 16.8 days (p = 0.85)

Overall Clinical Outcomes

Pre-treatment (No significant differences):

• Mean NPRS score: FSM group 5.9 ± 1.9 vs Control group 5.7 ± 2.2 (p = 0.44)
• Mean ODI/NDI score: FSM group 44.5 ± 17.5 vs Control group 41.3 ± 17.3 (p = 0.16)

Post-treatment:

• Mean NPRS score: FSM group 1.1 ± 1.7 vs Control group 1.7 ± 2.2 (p = 0.01) – Significantly lower in FSM group
• Mean ODI/NDI score: FSM group 16.9 ± 15 vs Control group 20.1 ± 15.1 (p = 0.10)

Treatment Outcomes:

• Full success: FSM group 74.5% vs Control group 59% (p = 0.03) – Significantly higher in FSM group
• Partial success: FSM group 17% vs Control group 28% (p = 0.04) – Significantly higher in FSM group
• Failure: FSM group 8.5% vs Control group 13%

Low Back Pain Results (167 FSM patients vs 61 Control patients)

Pre-treatment (No significant differences):

• Mean NPRS score: FSM group 6.0 ± 1.8 vs Control group 5.8 ± 2.3 (p = 0.49)
• Mean ODI score: FSM group 46.9 ± 16.7 vs Control group 44 ± 17.1 (p = 0.25)

Post-treatment:

• Mean NPRS score: FSM group 1.1 ± 1.7 vs Control group 1.7 ± 2.1 (p = 0.02) – Significantly lower in FSM group
• Patients with ≤3 NPRS score: FSM group higher percentage (p = 0.02) – Significantly better in FSM group
• Minimal disability category: FSM group higher percentage (p = 0.01) – Significantly better in FSM group
• Full success treatment outcome: FSM group significantly higher percentage (p = 0.006) – Significantly better in FSM group

Neck Pain Results (46 FSM patients vs 17 Control patients)

Pre-treatment (No significant differences):

• Mean NPRS score: FSM group 5.7 ± 1.9 vs Control group 5.2 ± 1.8 (p = 0.35)
• Mean NDI score: FSM group 34.7 ± 16.8 vs Control group 31.6 ± 14.8 (p = 0.50)

Post-treatment:

• Mean NPRS score: FSM group 1.1 ± 1.8 vs Control group 1.9 ± 2.7 (p = 0.17) – No significant difference
• Mean NDI score: FSM group 14.1 ± 11.7 vs Control group 14.6 ± 10.5 (p = 0.87) – No significant difference
• Treatment outcome: No significant difference in full success treatment outcome (p = 1.00)

Discussion

The results of this study show that the use of adjuvant FSM therapy along with an active rehabilitation protocol significantly reduced pain and disability when compared to patients treated with active rehabilitation protocol alone for low back pain. However, the addition of FSM did not appear to significantly affect clinical outcomes of pain and disability in patients with neck pain.

Effectiveness in Low Back Pain

The effectiveness of FSM application in patients with other musculoskeletal conditions has been previously reported in the literature. A previous study had reported that the application of FSM helped in preventing delayed onset muscle soreness (DOMS) up to 72 h post-exercise when compared to sham treatment. Similarly, microcurrent electrical neuromuscular stimulation (MENS), has been reported to enhance muscle function and improve physical activity in elderly patients. Furthermore, microcurrent application has been reported to be more effective than placebo or sham treatment in the treatment of musculoskeletal conditions and faster acting with lower complication rate when compared to transcutaneous electric nerve stimulation (TENS).

Mechanism of Action

To the best of our knowledge, this is the first and the largest study in the literature to report efficacy of FSM therapy on pain and disability in patients treated with rehabilitation therapy for low back and neck pain. In the current study, both pain intensity as measured by NPRS score and disability as measured by the ODI score was significantly better in LBP patients in the FSM group when compared to LBP patients in the control group. These findings validate similar findings previously reported by a small pilot study of 10 patients with nonspecific, chronic LBP where microcurrent application using a patch resulted in significant improvement in pain at the end of treatment.

Electrotherapy modalities such as TENS or interferential current, used in musculoskeletal pain, are based on the gate control theory of pain. Stimulation of peripheral sensory Aβ fibres by TENS inhibits or closes the “gate” (substantia gelatinosa) in the dorsal horn of spinal cord preventing transmission of sensory input from primary afferent neurons to the brain and inhibiting pain perception. However, the clinical effect of FSM occurs at a cellular level and involves a decrease in electrical resistance, restoration of cellular homeostasis, and facilitation of tissue regeneration in contrast to TENS which primarily works by blocking the transmission of pain signals.

Clinical Implications

Hence, improvement in clinical outcomes of patients with LBP treated with FSM in the current study may be primarily due to microcurrents promoting repair and regeneration of paraspinal muscles and reducing local inflammation as previously reported in animal models. Furthermore, we used directional movements using the Mechanical Diagnosis and Therapy (MDT) technique, and strengthening and stabilization exercises as the main component of physical rehabilitation treatment in all patients with LBP or NP which most likely accounted for the significant clinical improvement after treatment. However, the results of the current study indicate that the addition of FSM as an adjuvant therapy helped achieve a better outcome in LBP patients when compared to LBP patients where FSM was not used.

Limitations

This study has a few limitations:

1. Retrospective design: The retrospective design of the study has its inherent biases and limitations which may affect the generalizability of the study.
2. Follow-up period: The results reported were for a maximum treatment duration of 90 days. Hence the medium and long term implications of adjuvant FSM therapy in patients with LBP and NP are unknown and need further validation.
3. Psychosocial factors: Pain is a complex phenomenon and patient’s response to physical rehabilitation treatment may be dependent on their neurophysiological and psychosocial makeup which was not measured and analyzed in the current study.
4. Need for randomized controlled trials: A well-designed, randomized placebo-controlled trial needs to be undertaken to further confirm the benefits of adjuvant FSM therapy as a component of conservative management of LBP and NP.

However, these preliminary, encouraging results of adjuvant FSM therapy in LBP patients could form the basis for a randomized, placebo-controlled trial to investigate the efficacy of adjuvant FSM therapy in a larger number of patients with LBP and NP.

Conclusions

The use of adjuvant FSM application in patients treated with physical rehabilitation for low back pain significantly improved pain and disability when compared to patients where FSM was not used. Frequency specific microcurrent therapy could be a useful adjuvant in the rehabilitation treatment of patients with low back pain.

Author Information

Gautam M. Shetty: Conceptualization, Methodology, Data Analysis, Manuscript writing and editing.

Pallavi Rawat: Conceptualization, Data collection and curation, Reviewing final manuscript

Anjali Sharma: Data collection and curation, Reviewing final manuscript.

Affiliations:

• QI Spine Clinic, Mumbai, India
• QI Spine Clinic, Pune, India

Corresponding Author: Gautam M. Shetty, QI India Healthcare, #6 Level 2 Phoenix Market City, LBS Road, Kamani, Kurla (West), Mumbai, 400070, India. Email: gautam.shetty@qispine.com

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of Competing Interest

There are no conflicts of interest with any financial organization regarding the material discussed in the manuscript and this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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