By CAROLYN MCMAKIN, MA, DC
Frequency-specific microcurrent (FSM) has been used
for 10 years by numerous practitioners in various
specialties (MDs, DCs, NDs, PTs) to treat myofascial
pain and neuropathic pain in clinical practice (1-3).
This retrospective analysis of patients treated for
neuropathic pain in the author’s clinic presents a collected
case report in patients treated for monoradicular pain, in
an effort to quantify the results produced with FSM
treatment of neuropathic pain. The proposed mechanisms
of peripheral neuropathic pain will be compared with the
data associated with dual-channel, frequency-modulated
microamperage current to suggest a model for how
frequency-modulated microamperage current could be
producing the observed results. Central neuropathic pain
from postthalamic stroke and phantom limb pain, and
peripheral diabetic neuropathies have been successfully
treated using this method, but those types of neuropathic
pain were excluded from this analysis.
Neuropathic Pain and Cytokines
FSM has been shown to reduce inflammatory cytokines
while treating the pain of fibromyalgia associated with
spine trauma. In fibromyalgia associated with spine
trauma, patellar reflexes are hyperactive, there is specific
dermatomal hyperesthesia in addition to the allodynia
characteristic of central sensitization, and opioids are not
effective; all of which suggest pain of neuropathic origin.
One specific frequency combination, 40 Hz on one
channel and 10 Hz on the second channel delivered
simultaneously using polarized positive direct current, has
been shown to reduce IL-1 (330 to 80pg/ml, p=0.004),
Il-6 (239 to 76pg/ml, p=.0008), TNF α (305 to 78,
p=.002), and substance P (180 to 54pg/ml p=.0001), and
to increase endorphins (8.2 to 71.1pg/ml, p=.003). Pain
scores were reduced from an average of 7.3+/-1.2 to
1.3+/- 1.1 in 45 patients (p=.0001). No other frequency
combination reduced pain in this patient population.
This frequency combination is not effective in patients
whose fibromyalgia onset is not associated with spine
trauma and whose reflexes and dermatomal sensation are
normal. Fifty-eight percent of patients treated with this
protocol recovered from fibromyalgia within 4 months (4).
Neuropathic Pain and Prostaglandins
Studies have shown an association between the induction
of COX-2 increased prostaglandin release and enhanced
nociception in neuropathic pain. Expression of COX-1
and COX-2 in primary afferents and in the spinal cord
suggests that NSAIDs act there by inhibiting synthesis of
A study in a mouse model used arachidonic acidinduced lipoxygenase (LOX)- mediated inflammation to
create measurable swelling in mouse ears. This blinded
trial demonstrated a 62% reduction in ear swelling in all
animals treated with FSM using 40Hz on one channel
and 116Hz on the second channel when compared with
sham and the untreated controls. This was a t
Neuropathic Pain and Sodium Channels
The sodium channels in damaged nerves demonstrate
different depolarization characteristics than do
undamaged nerves (1,6). Following injury to their axons,
DRG neurons downregulate some sodium channel genes
and upregulate others, causing a different assortment of
sodium channels to be inserted into the DRG following
injury. The modified sodium channels have modified
properties that contribute to hyperexcitability in the
DRG, increased pain transmission, and sensitization (11).
There are several mechanisms by which current and
the voltage that drives it could influence voltage-gated ion
channels (VGICs) and sodium channels (VGSCs). The
battery-operated devices used in treatment put out pulsed
direct (DC) current. The frequencies delivered are not
pure sine wave frequencies, but rather square wave pulses.
Single channel, single frequency micro-amperage current
used alone on neuropathic pain did not demonstrate any
palliative or curative effect. However, the current must
have had some contribution to the observed effects,
because trial and error demonstrated that the treatments
for neuropathic pain are only effective if the positive
contact is placed on the spine at the point where the
nerve exits and the negative contact is placed at the distal
end of the nerve to be treated and the current is polarized
positive. The devices can output either alternating square
wave pulses or polarized positive or negative square wave
pulses. Only polarized positive pulses have been observed
to reduce neuropathic pain. Other types of pain, such as
myofascial pain from trigger points and delayed onset
muscle soreness, have been reduced with square wave
pulses of alternating DC current (1,2,10).
Cheng and associates demonstrated that applying
additional current to a biological system increases both
protein synthesis and energy production dramatically, as
long as the current was small enough. Direct current
levels of 50 to 1,000 μamps applied across rat skin
increased glycine (amino acid) transport by 75%
compared with untreated controls and current levels of
500 μamps increased aminoisobutyric acid (amino acid)
uptake by 90%, indicating a dramatic increase in protein
synthesis. Current levels above 1,000 μamps decreased
protein synthesis by as much as 50% (11).
Adenosine triphosphate (ATP) is the chemical energy
molecule that fuels most mammalian biological processes.
Direct current levels between 100 and 500 μamps applied
to rat skin increased ATP levels by 3 to 5 times (300% to
500%). Current exceeding 1,000 μamps caused ATP
production to level off, and currents above 5,000 μamps
reduced ATP levels as compared to untreated controls.
Once the external current was discontinued, ATP
production and amino acid transport levels returned to
baseline; there was no residual effect in rat skin (11). This
study has not been replicated in vivo or in humans.
The microcurrent devices used in treating neuropathic
pain are constant-current generators that increase the
voltage up to 30 volts as needed to maintain the current
levels set on the device. It has been proposed that VGICs
in cell and neural membranes may be affected by the
current and voltage flowing along or across the
membrane, but no one has measured changes in these
transport proteins in response to externally applied
microamperage current. VGICs require ATP activation to
change configuration allowing them to transport ions
across the cell membrane. If the current affects VGIC
function, it may do so simply by increasing ATP
production. While it is clear that current flow has an
effect on neuropathic pain, the exact mechanism needs to
Collected Case Report
Seventy-seven patients were selected for review from pain
clinic charts according to their diagnostic code indicating
neuropathic pain. Patients included in this paper had
sensory examinations and reflexes altered from normal
and a mechanism of injury that could reasonably have
caused neuropathic pain. Patients who did not have
pretreatment and posttreatment data for every visit, or
who met criteria for other diagnoses (eg, fibromyalgia,
diabetic peripheral neuropathy, postherpetic neuralgia)
were excluded. Twenty patients met criteria and were
included in the analyses. Sixteen (80%) were females and
4 (20%) were males. The average age was 47.70
(SD=11.19, range 24 to 68).
FSM can be applied using any 2-channel microamperage
current device that can provide frequency pulses accurate
to 3 digits on 2 channels simultaneously using alternating
or polarized positive DC current with a ramped square
wave pulse. Two different devices were used to deliver
treatments. The Precision Micro (Precision Microcurrent,
Newberg, Oregon), an analog, battery-operated 2-channel,
3- digit-specific microcurrent device was used for some
THE PAIN PRACTITIONER | VOLUME 20, NUMBER 3 | 69
treatment sessions. This device requires frequencies on
both channels to be set and changed manually. The
AutoCare, or AutoCare Plus (Microcurrent Technologies,
Seattle, Washington) was used during some treatments.
These are digital, battery-operated, 2-channel, 3-digitspecific microcurrent devices preprogrammed to run
certain specific frequency combinations for various time
periods. They include the protocols for treating
Patients must be adequately hydrated for the
treatment to be effective. In general, patients were
instructed to drink 1 to 2 quarts of water in the 3 to 4
hours before treatment. For treatment, the patients were
placed in a comfortable, supported position appropriate
to the nerve root being treated. The graphite glove
electrodes were wrapped in a warm, wet hand towel to
allow broad flexible skin coverage and good conductivity
(Figure 1). The positive contact was placed at the point
on the spine where the nerve exits. The negative contact
was placed at the distal end of the nerve to be treated and
the current was polarized positive. The frequencies
observed to reduce pain were 40Hz on one channel and
396 Hz on the second channel. The pain begins dropping
in minutes and declines in a time-dependent fashion over
30 minutes, requiring a maximum of 60 minutes to reach
optimal benefit. Treatment beyond 60 minutes did not
produce any additional improvement.
Once the pain was reduced, attempts to return to full
range of motion were observed to create pain or
sensations of pulling or aching in the affected nerve root.
Adhesions between nerves and the surrounding fascia and
between the nerve, cord, and dura are known to cause
pain and limit range of motion (11,12). Burn patients
with mature scarring were treated with certain frequency
combinations and experienced lasting increases in range
of motion (13). Postradiation scarring was modified and
range of motion increased by use of an impedancecontrolled, frequency-modulated microcurrent device (14).
Trial and error showed that if the patient was treated
with the frequencies 13Hz on one channel and 396 Hz on
the second channel while moving the limb (and nerve) to
edge of the range, within the limits of comfort, the range
of motion would return to normal within 10 to 15 minutes.
Only this frequency combination was useful for increasing
range of motion (Figure 2). The 40Hz and 396Hz
combination had no effect on increasing range of motion
and was useful only for reducing pain. 13Hz and 396 Hz
had no effect on reducing pain and were useful only for
In general, patients were treated twice weekly. Lowvelocity spinal manipulation was used after the
microcurrent treatment in some, but not all patients.
No patients reported or complained of side effects either
during or after treatment. The most common side effect
is a sensation of euphoria, presumably created by increases
in endorphins, such as those seen in the fibromyalgia
patients (8). It was not uncommon for patients to fall
asleep during the first treatment, but no patient
complained about this euphoric effect. Patients were kept
in the clinic after treatment until they returned to normal
and they were considered safe to drive.
If patients have bony foraminal or spinal cord stenosis,
the current and treatment protocol may cause a
temporary increase in pain that resolves over 24 hours
when the treatment is stopped. No increase in pain was
observed in any of the patients in this analysis.
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Figure 1. Positive leads are placed where the treated nerve exits the spine. Negative leads
are placed at the end of the dermatome. The leads are connected to graphite gloves and the
graphite gloves are wrapped in a warm, wet contact to allow coverage and convenient
placement. This placement treats the C5-C6-C7-C8 nerve roots.
Figure 2. When the pain is reduced and range of motion is still restricted, the frequencies
are set to 13Hz and 396Hz, and the affected nerve root and limb are moved gently through
range of motion. When the patient reports pressure or discomfort, the limb is returned to
neutral while the current and frequency continue to treat. The range is tested again and usually
increases with each attempt. Normal range is usually achieved within 15 minutes.
The chronicity of neuropathic pain varied from 1 week
to 44 years, with a mean of 6.69 years (SD=10.72).
Patients received an average of 4.60 treatments, with a
range from 1 to 15 (SD=3.75) treatments. The primary
mechanism of pain most commonly reported was a disc
injury (65%, n=13). Other mechanisms included traction
injuries (n=2), falls (n=1), other (n=1), and unknown (n=1).
Eleven patients had more than one mechanism of onset.
Of those, 7 (35%) indicated a motor vehicle accident as
the onset. No patient in this group had a lawsuit pending
related to an accident. In general, patients with disc injuries
required the greatest number of treatments; patients with
traction injuries required the fewest number of treatments.
Table 1 provides the means and standard deviations
for pretreatment and posttreatment pain scores for
treatments 1 through 4. The Wilcoxon Signed Ranks Test
was employed to compare patients’ pretreatment and
posttreatment pain scores. Since the average number of
treatments was 4.60, and 6 or fewer patients completed
treatment 5 and beyond, analyses were completed only
for treatments 1 through 4.
For treatment 1, the average initial pain score was
6.78 / 10 (SD= 1.80), with a range of 4 to 10. The
average pain score at the end of the first treatment was
1.83 / 10 (SD=2.10), with a range from 0 to 8. Even with
the outlier whose pain was reduced only from 10/10 to
8/10, the posttreatment pain scores were significantly
lower than pretreatment scores with Z= -3.83 and p<0.001.
For treatment 2, the mean pretreatment pain score
was 4.75 / 10 (+/- 2.60) and the mean posttreatment
score was 0.97/ 10 (SD = 1.6). The posttreatment pain
scores were significantly lower than pretreatment scores
with Z = -3.63 and p<0.001.
For treatment 3, the mean pretreatment pain score
was 5.14/10 (SD = 1.99) and the mean posttreatment
pain score was 0.46 / 10 (SD = 0.84). Posttreatment
scores were significantly lower than pretreatment scores,
with Z = -3.30 and p<0.01.
For treatment 4, the mean pretreatment score was
3.94/10 (1.96) and the mean posttreatment score was
0.29/10 (SD = 0.76). The posttreatment scores were
significantly lower, with Z = -2.37, and p<0.05.
Of the 20 patients reviewed, 65% (n=13) fully
recovered from nerve pain. Twenty-five percent
terminated care before recovery (n=5) for reasons not
associated with the treatment. One patient was referred
for additional treatment by epidural steroid injection.
One patient purchased a small automated microcurrent
unit for home use while her disc injury healed.
This retrospective analysis of a typical assortment of
chronic neuropathic pain patients attempts to quantify
the anecdotal reports of successful treatment of chronic
neuropathic pain using frequency-specific microcurrent.
Patients improve most dramatically during the first 4
treatments. Patients with traction injuries usually recover
within 2 to 3 treatments. Patients with disc injuries and
ligamentous laxity, especially in the cervical spine, require
the greatest number of treatments because the discs and
ligaments that are perpetuating the neuropathic pain need
time, spinal stabilization exercises, and other forms of
physical therapy to heal.
All patients reported some reduction in pain with
treatment. The patients who terminated care did so even
after treatment had reduced pain and did so for reasons
not related to treatment side effects such as cost, travel
time, and other personal situations.
Only the frequencies 40 Hz on one channel and 396
Hz on the other channel reduced pain. Only the
frequencies 13 Hz on one channel and 396 Hz on the
other channel increased range of motion.
As seen in the mouse trial and the fibromyalgia
patients, patient response to the current and frequency
combinations to reduce nerve pain were time dependent
(8,10). Thirty to 60 minutes of treatment were required
to reduce pain from an average of 6.78/10 to an average
72 | THE PAIN PRACTITIONER | FALL 2010
DEPARTMENT | RHEUMATOLOGY | NONPHARMACOLOGIC TREATMENT OF NEUROPATHIC PAIN USING FREQUENCY SPECIFIC MICROCURRENT
Treatment # (n) Pre-Tx Mean (SD) Pre-Tx Range Post-Tx Mean (SD) Post-Tx Range
Treatment 1 (n=20) 6.78 (1.80) 4-10 1.83 (2.10) 0-8
Treatment 2 (n=17) 4.75 (2.56) 2-10 0.97 (1.60) 0-4 ………..
Treatment 3 (n=14) 5.14(1.99) 1-8 0.46 (.84) 0-2 ………..
Treatment 4 (n=7) 3.94 (1.96) 2-8 0.29 (.76) 0-2 ………..
of 1.83 /10 on a 0-10 VAS scale on the first treatment.
Approximately 30 minutes of treatment were required to
reduce pain from 4.75/10 to 0.97/10 for the second
treatment. At the 15-minute mark, approximately half of
the eventual effect was present.
The 30- to 60-minute treatment time required to reduce
neuropathic pain corresponds to the time-dependent
response seen in the mouse anti-inflammatory research. In
the mice, half of the effect was produced in 2 minutes and the
full effect was seen at 4 minutes. Additional treatment time
beyond 4 minutes did not produce any additional effect (8).
In neuropathic pain in humans, the pain begins to be
reduced within a 15-minute treatment time, but 30 to 60
minutes are required to create optimal lasting reductions in
pain. The frequencies to increase range of motion have their
effect more quickly than those to reduce inflammation and
pain but are still time dependent. The frequency must be
used for 10 to 15 minutes in combination with movement
to produce an optimal increase in range of motion.
Dual channel, specific-frequency microamperage current
produced dramatic improvements in a collected case
report of patients with chronic neuropathic pain.
Treatment is noninvasive, low risk, widely available,
relatively inexpensive, and appears to have no significant
side effects. A controlled trial should be performed to
further evaluate its effectiveness in this otherwise difficult
patient group. ■
CAROLYN MCMAKIN, MA, DC, is the
clinical director of the Fibromyalgia and
Myofascial Pain Clinic of Portland,
Oregon. She developed frequency specific
microcurrent (FSM) in 1996. She
maintains a part-time clinical practice,
participates in research, and teaches
seminars on the use of FSM. She has
published five peer reviewed papers on the use of FSM in the
treatment of myofascial pain, fibromyalgia, delayed onset muscle
soreness, and shingles. She has lectured at the National Institutes
of Health and at numerous medical conferences in the US,
England, Canada, and Australia, on the subjects of fibromyalgia,
fibromyalgia associated with cervical trauma, and on the
differential diagnosis and treatment of chronic pain syndromes.
Her textbook titled Frequency Specific Microcurrent in Pain
Management is in press with Elsevier to be released in 2010.
Disclosure: No grants or financial recompense were
involved in this case report. Carolyn McMakin is
president of Frequency Specific Seminars, Inc.
Acknowledgements: The author wishes to acknowledge the
assistance with data collection and analysis provided by
Jessica Morea Irvine, MS and the advice and inspiration
provided by Dr. David G Simons in the preparation of
Correspondence: Carolyn McMakin,
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