Effect of adjuvant frequency-specific microcurrents on pain and disability in patients treated with physical rehabilitation for neck and low back pain

Low back Neck Pain paper JBMT

Myofascial Pain and Treatment
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 a, *

, Pallavi Rawat b

, Anjali Sharma b

a QI Spine Clinic, Mumbai, India
b QI Spine Clinic, 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 cate-
gories, 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 1⁄4 0.02) and a
significantly higher percentage of patients were in the 3 NPRS score (p 1⁄4 0.02), in the minimal
disability (p 1⁄4 0.01), and the full success (p 1⁄4 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.

1. Introduction
Electrophysical modalities such as transcutaneous electrical

nerve stimulation (TENS), interferential current stimulation, dia-
dynamic current stimulation, and high-voltage electrical stimula-
tion are used for pain management in patients with

musculoskeletal conditions (Almeida et al., 2018; Rajfur et al., 2017;
Gibson et al., 2019; Logan et al., 2017; White et al., 2017). 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 (Resende et al., 2018). However, another systematic re-
view 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 (Wu et al., 2018).

Frequency-specific microcurrent (FSM) is an electrophysical
modality used in pain management that delivers very low-intensity
electric current to tissues within the microampere (mA) range,
approximately 1000 times lower than the current intensity used in
TENS (McMakin, 2011, 2017). 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 trans-
mission of pain signals (McMakin, 2011, 2017). 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 inflamma-
tion, and promote healing by maintaining intracellular Ca2þ ho-
meostasis and upregulating ATP production (McMakin, 2011; Kwon

et al., 2014; Fujiya et al., 2015; Lambert et al., 2002).

Although previous studies have reported the efficacy of micro-
current in improving muscle function in musculoskeletal condi-
tions such as delayed onset muscle soreness, congenital muscular

torticollis, spastic myocontracture in cerebral palsy, and age-related
muscle weakness (Lambert et al., 2002; Curtis et al., 2010; Kim
et al., 2009; Maenp € €

aa et al., 2004 € ; Kwon et al., 2017), 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 pa-
tients treated with physical rehabilitation for LBP and NP. We hy-
pothesized 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.
2. Patients and methods
2.1. 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 reha-
bilitation (QI Spine Clinic, Pune) from October 2016 to January 2019

were analyzed. The inclusion criterion was all patients with LBP or

NP, more than 20 years of age, who underwent physical rehabili-
tation treatment at our clinics. The exclusion criteria were 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 neu-
ropathy, patients with complex regional pain syndrome (CRPS),

patients with lumbar canal stenosis (LCS) and, patients who did
physiotherapy for less than 1 month or more than 3 months at the
centre.
2.2. 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. Based on the exclusion criteria, 93
patients were excluded due to inflammatory causes of LBP or NP,
peripheral neuropathy or joint involvement, associated kyphotic or
scoliotic deformities, CPS and LCS and 505 patients were excluded
based on the duration of treatment of less than 1 month or more
than 3 months in the FSM group. Similarly, based on the exclusion
criteria, 48 patients were excluded due to inflammatory causes of
LBP or NP, peripheral neuropathy or joint involvement, associated
kyphotic or scoliotic deformities, CPS and LCS and 250 patients
were excluded based on the duration of treatment of less than 1
month or more than 3 months in the control group. Hence, 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.

2.3. Outcome measures

All patients were evaluated clinically before and during treat-
ment for their LBP or NP. A thorough history of presenting com-
plaints, 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 nu-
merical 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 (Childs et al.,

2005; Fairbank and Pynsent, 2000; Vernon, 2008). Using the Me-
chanical Diagnosis and Therapy (MDT) system, all patients were

evaluated by movement testing and diagnosed as reducible
derangement, irreducible degrangement, postural syndrome,
dysfunction syndrome, or others by a senior physiotherapist in
the clinic (McKenzie and May, 2003, 2008).
2.4. Treatment protocol

A multimodal, active rehabilitation protocol involving a com-
bination 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 appli-
cation 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. Based on the severity of LBP or
NP on NPRS during the first assessment, 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 if NPRS score was
7. Patients who opted for FSM therapy were administered FSM as
a 30-min session, every day during the first 1 week of treatment.
Once the pain on NPRS score was 4e7 or in patients presenting with
pain on NPRS score 4e7, 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. Once
the pain on NPRS was <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 was considered a full success if the
patient shifted to a disability category of “minimal” and had pain
improvement on NPRS of >80%, a partial success if the patient
improved in disability by one category (e.g.: a shift from severe to
moderate category) and pain improvement on NPRS of 30%e80% ,
and a failure if patients did not fall into the full or partial success
category at the end of treatment.

2.5. 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. Similarly, clinical outcome data
such as NPRS score, percentage of NPRS score improvement, ODI/
NDI score, disability category, and treatment outcome category
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 be-
tween 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 (SPSS Science Inc, Chicago, IL).
3. Results
3.1. Comparison of baseline parameters between FSM vs control
groups
The baseline characteristics of the 213 patients in the FSM group
and 78 patients in the control group are compared in Table 1. The
mean age (p 1⁄4 0.15), mean BMI (p 1⁄4 0.83), gender ratio (p 1⁄4 0.88),
anatomical case type (p 1⁄4 1.00), lifestyle (p 1⁄4 0.43), presence of
night pain (p 1⁄4 0.88), diagnosis based on MDT (p 1⁄4 1.00), response
to movement testing (p 1⁄4 1.00), mean treatment duration
(p 1⁄4 0.85) and the mean number of treatment sessions done by the
patients (p 1⁄4 1.00) were not significantly different when the 2
groups were compared (Table 1).
3.2. Comparison of clinical outcomes between FSM vs control
groups
Clinical outcomes in patients in the FSM group and patients in
the control group are compared in Table 2. Pre-treatment, the mean
NPRS score (p 1⁄4 0.44), mean ODI/NDI score (p 1⁄4 0.16), distribution

of patients in NPRS categories (p 1⁄4 0.37), and distribution of pa-
tients in disability categories (p 1⁄4 0.66) were not significantly

different when the 2 groups were compared (Table 2). Post-
treatment, the mean NPRS score was significantly lower

(p 1⁄4 0.01) in the FSM group compared to the control group whereas
the distribution of patients in NPRS categories was not significantly

different (p 1⁄4 0.10) when the 2 groups were compared. The post-
treatment mean ODI/NDI score was not significantly different

(p 1⁄4 0.10) when the two groups were compared whereas a signif-
icantly higher percentage of patients (p 1⁄4 0.03) were in the mini-
mal disability category in the FSM group when compared to

patients in the control group (Table 2). Overall, in terms of treat-
ment outcome, a significantly higher percentage of patients were in

the full success (p 1⁄4 0.03) and the partial success (p 1⁄4 0.04) cate-
gories in the FSM group when compared to the control group.

3.3. Comparison of clinical outcomes between FSM vs control
groups in patients with low back pain (LBP)
A total of 167 patients (78.5%) in the FSM group had LBP whereas
61 patients (78%) in the control group had LBP. Pre-treatment, the

mean NPRS score (p 1⁄4 0.49), mean ODI score (p 1⁄4 0.25), distribu-
tion of patients in NPRS categories (p 1⁄4 0.37), and distribution of

patients in disability categories (p 1⁄4 0.66) were not significantly

different when the 2 groups were compared (Table 3). Post-
treatment, the mean NPRS score was significantly lower

(p 1⁄4 0.02) in the FSM group compared to the control group and a
significantly higher percentage of patients (p 1⁄4 0.02) were in the
3 NPRS score category in the FSM group when compared to the
control group (Fig. 1). Similarly, a significantly higher percentage of
patients (p 1⁄4 0.01) were in the minimal disability category in the
FSM group when compared to the control group (Fig. 2). However,
the post-treatment mean ODI score was not significantly different
(p 1⁄4 0.09) when the two groups were compared (Table 3). Overall,
in terms of treatment outcome, a significantly higher percentage of
patients were in the full success (p 1⁄4 0.006) category in the FSM
group when compared to the control group (Fig. 3).
3.4. Comparison of clinical outcomes between FSM vs control
groups in patients with neck pain (NP)
A total of 46 patients (21.5%) in the FSM group had NP whereas
17 patients (22%) in the control group had NP. Pre-treatment, the
mean NPRS score (p 1⁄4 0.35), mean NDI score (p 1⁄4 0.50),

distribution of patients in NPRS categories (p 1⁄4 0.37), and distri-
bution of patients in disability categories (p 1⁄4 0.66) were not

significantly different when the 2 groups were compared (Table 3).
Post-treatment, the mean NPRS score (p 1⁄4 0.17) mean NDI score
(p 1⁄4 0.87), percentage of patients in the 3 NPRS score category
(p 1⁄4 0.07) (Table 3), and percentage of patients in the minimal
disability category (p 1⁄4 0.73) were not significantly different when
the 2 groups were compared (Figs. 4 and 5). Overall, in terms of
treatment outcome, there was no significant difference in the
percentage of patients (p 1⁄4 1.00) who had full success treatment
outcome category when the 2 groups were compared (Fig. 3).
4. 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. How-
ever, the addition of FSM did not appear to significantly affect

clinical outcomes of pain and disability in patients with neck pain.

The effectiveness of FSM application in patients with other
musculoskeletal conditions has been previously reported in the
literature (Lambert et al., 2002; Curtis et al., 2010; Kim et al., 2009;

Maenp € a€a et al., 2004 € ; Kwon et al., 2017). A previous study had re-
ported that the application of FSM helped in preventing delayed

onset muscle soreness (DOMS) up to 72 h post-exercise when
compared to sham treatment (Curtis et al., 2010). Similarly,
microcurrent electrical neuromuscular stimulation (MENS), has
been reported to enhance muscle function and improve physical
activity in elderly patients (Kwon et al., 2017). Furthermore,
microcurrent application has been reported to be more effective

than placebo or sham treatment in the treatment of musculoskel-
etal conditions (Maul et al., 2019; Naclerio et al., 2019; Kwon et al.,

2017; Curtis et al., 2010; Koopman et al., 2009; Bertolucci and Grey,
1995) and faster acting with lower complication rate when
compared to transcutaneous electric nerve stimulation (TENS)
(Saranya et al., 2019; Bertolucci and Grey, 1995).
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 (Koopman et al., 2009). In the current study, the beneficial
effect of adjuvant FSM application seen in LBP patients was not seen
in patients with neck pain. This could be due to the small number of
patients in the NP sub-group when compared to the LBP sub-group.
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 Ab 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 (Mokhtari et al.,

2020; Moayedi and Davis, 2013). However, the clinical effect of FSM

occurs at a cellular level and involves a decrease in electrical resis-
tance, restoration of cellular homeostasis, and facilitation of tissue

regeneration in contrast to TENS which primarily works by blocking
the transmission of pain signals (McMakin, 2011, 2017). 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 (Fujiya et al., 2015). 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 hel-
ped achieve a better outcome in LBP patients when compared to LBP

patients where FSM was not used.

This study has a few limitations. First, the retrospective design
of the study has its inherent biases and limitations which may

affect the generalizability of the study. Second, the results re-
ported were reported 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. Third, pain is a complex phenomenon and
patient’s response to physical rehabilitation treatment may be
dependent on their neurophysiological and psychosocial makeup
(Smeets et al., 2009; Macedo et al., 2014) which was not measured

and analyzed in the current study. Hence, future studies evalu-
ating the efficacy of FSM therapy in the treatment of LBP or NP

should take into account the effect of neurophysiological and
psychosocial factors on clinical outcomes. Finally, 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 ther-
apy in a larger number of patients with LBP and NP.

5. 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.

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