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1.Name the statistical test(s) that are used in this article.
2.Describe how the data is presented (tables, graphs, charts etc) and state whether you found the data was readily understood based on the presentation.
3.Describe the studys conclusions. Are they clearly stated and substantiated by the evidence presented and are the implications of the findings discussed?
4.Are the results generalized to any population? Give examples.
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Journal of Back and Musculoskeletal Rehabilitation 17 (2004) 127–133 127
IOS Press
Efficacy of transcutaneous electrical nerve
stimulation and percutaneous
neuromodulation therapy in chronic low back
pain
Oya Topuz*, Erhan O¨ zfidan, Merih Ozgen and Fu¨sun Ardic
Department of Physical Medicine and Rehabilitation, Pamukkale University, Denizli, Turkey
Abstract. The studywas designed to compare the efficacy of two different modalities of transcutaneous electrical nerve stimulation
(conventional and low-frequency TENS) (C-TENS and Low-TENS) and percutaneous neuromodulation therapy (PNT) in the
treatment of chronic low back pain. Sixty patients with chronic low back pain were randomly divided into four groups as
placebo-TENS, C-TENS, Low-TENS, and PNT. Therapeutic modalities were administered for 2 weeks. The pre-treatment and
post-treatment assessments were done by using the Visual Analog Scale for pain; Low Back Pain Outcome Scale and Oswestry
Disability Index for functional disability; and Health Status Survey Short Form (SF-36) for quality of life. In placebo-TENS group
only emotional role limitation score of SF-36 significantly decreased after the treatment. All measurements except emotional role
limitation score of SF-36 significantly improved in C-TENS group after the treatment. In both of Low-TENS and PNT groups,
all parameters were significantly improved by the treatment. TENS modalities and PNT were significantly more effective than
the placebo-TENS. No significant difference was found between C-TENS and Low-TENS. PNT was significantly more effective
than TENS in providing relief of activity pain and in improving general health, vitality and emotional role limitation scores of
health quality.
1. Introduction
Electrical nerve stimulation is often used for the relief
of acute and chronic pain or as an adjunct therapy
for the main intervention. Transcutaneous electrical
nerve stimulation (TENS) currently is one of the most
commonly used forms of electroanalgesia. Although,
TENS is popular in pain management, and the patients
treated with TENS reported less pain and better functional
status, the evidence from randomized controlled
trials does not support the use or the non-use of TENS
alone in the treatment of chronic low back pain [2].
Percutaneous neuromodulation therapy (PNT), previ-
*Adress for correspondence: Oya Topuz, C¸ amkent sitesi, No: 49
C¸ amlik, Denizli, Turkey. Tel.: +90 258 2110254; Fax: +90 258
2118129; E-mail: otopuz@pamukkale.edu.tr.
ously known as percutaneous electrical nerve stimulation
(PENS), is an effective, minimally invasive, electrical
nerve stimulation approach to the management
of low back pain. Unlike TENS, which delivers electrical
current through special pads positioned on the
skin surface, PNT penetrates the skin via a series of
acupuncture-like needles.
The purported mechanism of action of TENS invokes
both spinal (i.e., gate-control, frequency-dependent
blockade) and supraspinal theories (i.e., release of endogenous
neuromediators). It was initially theorized
that the effect of low frequency TENS was mediated
by the endogenous opioid system, whereas the effect
of conventional TENS was mediated by other mechanisms,
such as gate control. However it was appears
that both low and high frequency TENS stimulate the
endogenous opioid system, but the type of response is
dependent on stimulation frequency [16]. The main ad-
ISSN 1053-8127/04/$17.00 ? 2004 – IOS Press and the authors. All rights reserved
128 O. Topuz et al. / Efficacy of TENS and PNT in chronic low back pain
Table 1
Comparison of the baseline characteristics of the groups
PLACEBO TENS (n = 12) C-TENS (n = 15) Low-TENS (n = 15) PNT (n = 13) P value
(mean ± SD) (mean ± SD) (mean ± SD) (mean ± SD)
Age ( years) 41.92 ± 7.70 45.20 ± 11.19 50.13 ± 11.97 37.92 ± 14.49 0.106
Gender, female (%) 91.7 60 73.3 76.9 0.319
Duration of pain (month) 16.81 ± 8.75 16.46 ± 9.78 20.53 ± 14.42 15.30 ± 13.28 0.746
Beck Depression Inventory 8.08 ± 6.18 8.46 ± 5.28 10.20 ± 6.20 13.53 ± 7.12 0.120
vantage of PNT over TENS is that it bypasses the local
skin resistance and delivers electrical stimuli at the precisely
desired level in close proximity to the nerve endings
located in soft tissue, muscle, or periosteum [23].
In a number of controlled clinical trials PNT is an
effective treatment for back pain [7,8,12,18]. On the
other hand, psychological situation of patients may effect
evaluation of pain and disability in chronic pain [6,
17]. Studies, with comparable groups in respect to
self-reported depression scale, may give more definite
results.
The aim of this randomized, controlled study was to
determine and compare the efficacy of different electroanalgesic
modalities (Conventional-TENS, low frequency
TENS and PNT) on pain, disability and health
quality in patients with chronic low back pain. To our
knowledge, this is the first study comparing all of these
treatment modalities in chronic low back pain.
2. Methods
2.1. Subjects
Sixty patients (19 men, 41women) ages between 19–
70 years with low back pain at least for three months
were included in this study. Patients were recruited
consecutively from the outpatient clinic of a Physical
Medicine and Rehabilitation Department. The exclusion
criteria included history of cancer, the use of
corticosteroids or anticoagulant agents, the use of cardiac
pacemaker, prior lumbar spine surgery, known
hearth disease, severe coexisting disease, or presence
of vertebral fracture, spinal infection, spinal tumor, severe
ortophedic abnormalities or presence of nerve root
irritation findings. To enhance blinding of the subjects
to their treatment assignment, we excluded candidates
who had previously used any therapeutic electrical
stimulation modality. All of the patients were ambulatory
and were judged to be sufficiently intelligent
to carry out the instructions of the study.
2.2. Treatment assignment and description
In this prospective randomized placebo-controlled
study, the patients were administered four different
electrical stimulation modalities; placebo-TENS,
conventional TENS (C-TENS), low frequency TENS
(Low-TENS) and PNT. Random assignment was performed
by drawing from sealed envelopes to ensure approximately
equal numbers of patients in the treatment
groups. All patients had one session therapy per day
for two weeks, except weekends.
TENSwas performed with Trio 300 units (ITOCorp.
Japan) that generates symmetric, bi-phasic rectangular
pulses with 100 µs duration. Four medium sized (2 ×
2 cm) carbon impregnated rubber cutaneous electrodes
were placed bilaterally in a standard dermatomal pattern
over the most painful lumbar region. The subjects
in the conventional-TENS group (n = 15) received
high frequency electrical stimulation (80 Hz), and current
intensitywas increased up to patient’s perception of
paraesthesia. The subjects in the low-frequency TENS
group (n = 15) received low frequency electrical stimulation
(4 Hz), and current intensity was increased up
to maximum tolerated amplitude without muscle contractions.
In placebo-TENS group (n = 12) the electrodes
were placed to the same position but no electrical
stimulation was applied to the electrodes. All subjects
were told that they might or might not perceive
the stimulation, that stimulation was sometimes below
a persons’ threshold of perception, and this should not
be of concern.
PNT was performed with IC 4107 units (ITO Corp.
Japan) that generates unipolar square-wave pulses with
100 µs duration. The subjects in the PNT group
(n = 13) received low frequency electrical stimulation
(4Hz), and current intensity was increased up to maximum
tolerated amplitude to produce highest electrical
“tapping” sensation without muscle contractions. Four
32 gauge stainless steel acupuncture-like needle electrodes
were placed symmetrically into the soft tissue
to a depth of 2–4 cm in a standard dermatomal pattern
over the most painful lumbar region.
Modalities were administered for a period of 20 min,
five times per week, for 2 weeks.
O. Topuz et al. / Efficacy of TENS and PNT in chronic low back pain 129
Table 2
Comparison the pre-treatment and the post-treatment clinical characteristics of the groups, and comparison of the ? Scores between the groups
Placebo Tens (n = 12) C-TENS (n = 15) Low-TENS (n = 15) PNT (n = 13)
(mean ± SD) (mean ± SD) (mean ± SD) (mean ± SD)
Pain (VAS)
Current pain Pre-treat. 5.75 ± 1.35 6.53 ± 1.18 6.86 ± 1.24 7.00 ± 1.47
Post-treat 5.91 ± 1.37 3.73 ± 1.62a 4.26 ± 2.05a 3.38 ± 2.66a
? Score 0.16 ± 1.11 -2.80 ± 2.00b -2.60 ± 1.40b -3.61 ± 1.98b
Activity Pain Pre-treat. 6.75 ± 1.13 7.40 ± 1.18 7.46 ± 1.92 8.15 ± 1.21
Post-treat 6.58 ± 0.99 4.86 ± 1.68a 5.33 ± 2.09a 4.07 ± 2.49a
? Score -0.16 ± 0.83 -2.50 ± 1.45b,c -2.15 ± 1.18b,c -4.07 ± 1.75b
Functional disability
LBPOS Pre-treat. 52.75 ± 7.42 44.80 ± 9.08 43.93 ± 11.80 46.23 ± 10.78
Post-treat 52.91 ± 11.15 58.53 ± 14.36a 56.86 ± 10.50a 61.69 ± 16.89a
? Score 8.33 ± 5.86 13.55 ± 9.63b 12.80 ± 7.00b 15.38 ± 12.95b
ODI Pre-treat. 16.16 ± 5.78 20.00 ± 6.52 20.00 ± 7.86 22.07 ± 9.10
Post-treat 18.33 ± 5.21 14.20 ± 8.88a 12.26 ± 6.60a 12.53 ± 10.26a
? Score 2.16 ± 3.29 -6.60 ± 5.70b -7.73 ± 4.26b -9.53 ± 4.85b
Quality of life(SF-36)
Physical function Pre-treat. 63.30 ± 13.87 50.33 ± 18.94 46.93 ± 19.64 52.69 ± 24.46
Post-treat 59.58 ± 17.24 66.00 ± 21.14a 65.00 ± 20.26a 76.92 ± 22.22a
? Score -3.75 ± 13.33 15.66 ± 22.42b 17.60 ± 13.78b 24.23 ± 19.02b
Social functioning Pre-treat. 68.33 ± 13.70 58.33 ± 24.39 7.50 ± 20.70 6.92 ± 19.31
Post-treat 59.37 ± 22.69 69.16 ± 24.02a 62.16 ± 11.25a 76.92 ± 17.56a
? Score -6.87 ± 17.02 10.83 ± 13.25b 11.66 ± 11.90b 20.00 ± 11.72b
Physical role limitations Pre-treat. 27.08 ± 37.62 18.33 ± 38.84 6.66 ± 11.44 24.35 ± 33.23
Post-treat 22.92 ± 34.47 54.44 ± 39.19a 41.66 ± 27.81a 63.46 ± 40.33a
? Score -16.66 ± 35.88 36.10 ± 42.91b 35.00 ± 28.03b 39.10 ± 33.91b
Emotional role limitations Pre-treat. 55.28 ± 35.95 51.08 ± 37.51 33.30 ± 25.19 35.86 ± 31.78
Post-treat 33.05 ± 28.43a 62.19 ± 33.02 64.41 ± 34.42a 82.03 ± 32.25a
? Score -22.26 ± 32.82 11.10 ± 24.11b,c 31.10 ± 29.46b 46.16 ± 28.98b
General mental health) Pre-treat. 61.00 ± 13.86 65.33 ± 11.17 63.00 ± 14.02 67.38 ± 10.17
Post-treat 58.66 ± 10.83 70.40 ± 8.91a 70.13 ± 16.68a 73.53 ± 8.25a
? Score -2.33 ± 10.98 5.06 ± 6.67b 6.86 ± 7.60b 6.15 ± 5.06b
Vitality Pre-treat. 60.41 ± 14.21 66.33 ± 11.41 9.00 ± 19.01 62.69 ± 13.16
Post-treat 60.83 ± 9.73 71.33 ± 9.15a 65.86 ± 19.90a 75.00 ± 12.74a
? Score 0.41 ± 9.87 4.66 ± 7.89c 6.86 ± 9.07 12.30 ± 10.72b
Bodily pain Pre-treat. 46.16 ± 14.03 41.53 ± 17.81 34.66 ± 10.64 42.26 ± 18.15
Post-treat 43.91 ± 14.84 54.40 ± 19.05a 49.40 ± 13.82a 61.38 ± 20.17a
? Score -2.25 ± 6.38 12.73 ± 12.80b 14.73 ± 7.77b 18.80 ± 11.05b
General health perception Pre-treat. 59.83 ± 12.37 57.80 ± 18.04 49.86 ± 18.23 45.84 ± 15.29
Post-treat 56.91 ± 12.63 65.53 ± 17.44a 60.20 ± 21.39a 66.40 ± 17.59a
? Score -2.91 ± 6.03 7.60 ± 12.07b,c 10.33 ± 11.53b,c 21.32 ± 14.53b
Pre-treat.: Pre-treatment score, Post-treat.: Post-treatment score,
LBPOS: Low Back Pain Outcome Scale.
ODI: Oswestry Disability Index.
? Score: Post-treatment score – Pre-treatment score.
aSignificantly different from value prior to receiving the treatment,P <0.05.
bSignificantly different from Placebo TENS,P < 0.05.
cSignificantly different from PNT,P <0.05.
2.3. Assessment procedures
The pre-treatment and post-treatment assessments
were done by using the Visual analog scale (VAS)
scores for current and activity pain; Low Back Pain
Outcome Scale and Oswestry Disability Index for functional
disability; Health Status Survey Short Form (SF-
36) for quality of life. Prior to treatment, all patients
completed Beck Depression Inventory(BDI) for evaluating
of depression.
Current pain perception and activity pain was
recorded with a standart 10-cm visual analog system,
from a score of “0” equalling the best, to a score of
“10” equalling the worst.
Back-specific functional status was assessed by using
two disability ratings. The LowBack Pain Outcome
Scale is a 13 items questionnaire intended as a com130
O. Topuz et al. / Efficacy of TENS and PNT in chronic low back pain
prehensive rating system for patients with back pain.
It includes questions that pertain to current pain, employment,
domestic and sport activities, use of drugs
and medical services, rest, sex life and daily activities.
This is scored from 0 to 75. Increasing scores represent
improved function [11]. Oswestry Low Back
Pain Disability Questionnaire consisted of 10 items assessing
the level of pain, and interference with several
physical activities, sleeping, self care, sex life, social
life and traveling. The scale is one of the most widely
used outcome measures for patients with lowback pain.
Decreasing scores represent improved function [4].
The SF-36 generic health questionnaire is becoming
the established tool of choice for monitoring patient’s
health status. It describes eight domains of
health: physical function(PF), social functioning(SF),
physical role limitations (RP), emotional role limitations(
RE), general mental health(MH), vitality(VT),
bodily pain(BP), general health perception (GH). Each
domain is scored from 0 (poor health) to 100 (optimal
health). Higher scores reflect better function [21].
The Beck Depression Inventory is a 21-item selfreport
yielding a numerical estimate of depression
severity. Patients select one of four or five statements
ranked in order of severity in each item. Scores range
from 0 to 63, with high scores indicating greater depression
[1].
2.4. Analysis
Subjects were evaluated before and after the treatment.
The change in the scores were used as a measure
of improvement. It was defined by subtracting the
pre-treatment score from the post-treatment score (?
Score = Post-treatment score – Pre-treatment score).
For the Low Back Pain Outcome Scale and SF-36, a
greater change in score means that the treatment was
more effective. For the VAS and Oswestry Disability
Index a higher negative change in score indicates
greater improvement. Data are presented as the mean
± standart deviation. Wilcoxon’s signed ranked test
was used to determine whether there was a significant
difference between pre- and post-treatment results for a
group. Kruskal-Wallis (among four groups) and Mann
Whitney-U tests (between two groups) were used to
compare pre-treatment means and change of score. A
difference was considered significant atP <0.05.
3. Results
Five patients (%8.3) were dropped out from the
study. Three patients of placebo TENS group, and two
patients of PNT group did not continue the therapy
due to personal reasons. Fifty-five patients (14 men,
41women) completed the study. The average age of the
patientswas 44.11±12.21 years, and the average duration
of pain was 17.40 ± 11.72 months. There were no
statistically significant difference in age, sex, pain duration
and BDI score among the four groups (Table 1).
There were also no statistically significant differences
in scores of current pain, activity pain, Low Back Pain
Outcome Scale, Oswestry Disability Index and SF-36
before treatment among the four groups. In placebo-
TENS group only emotional role limitation score of SF-
36 significantly decreased after the treatment. Current
pain, activity pain, Low Back Pain Outcome Scale, Oswestry
Disability Index and SF-36 scores except emotional
role limitation score was significantly improved
in C-TENS group. Significantly improvements in current
pain, activity pain, Low Back Pain Outcome Scale,
Oswestry Disability Index and SF-36 scores were seen
after the Low-TENS treatment and PNT treatment (Table
2). PNT and TENS modalities were significantly
more effective than placebo TENS in respect to current
pain, activity pain, Low Back Pain Outcome Scale, Oswestry
Disability Index and SF-36 (p < 0.05). With
PNTtreatment, improvements in activity pain score and
general health score of SF-36 were significantly better
than C-TENS and Low-TENS treatment (p < 0.05).
PNT was also significantly more effective on emotional
role limitation and vitality score of SF-36 than C-TENS
treatment (p < 0.05). However improvements in current
pain, activity pain, Low Back Pain Outcome Scale,
Oswestry Disability Index and SF-36 scores did not differ
between the C-TENS group and Low-TENS group
(Table 2, Figs 1–3).
4. Discussion
We have found that PNT was more effective on activity
pain and general health scale of SF-36 than Low-
TENS, and PNT was more effective on activity pain
and general health, vitality and emotional role limitation
scales of SF-36 than C-TENS. All of the treatments
were more effective on pain, disability and health
quality than placebo-TENS. There was no difference
between conventional or low-frequency application for
TENS.
O. Topuz et al. / Efficacy of TENS and PNT in chronic low back pain 131
-4.5
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
Current Pain Activity Pain
VAS
PLACEBO TENS C-TENS Low-TENS PNT
† Significantly different from
Significantly different from
Placebo TENS, P<0.05.
PNT, P<0.05.
-treatment VAS – Pre-treatment VAS
†
†
†
†+
†
†+
Fig. 1. Comparison of improvements in the pain scores of the groups.
-15
-10
-5
0
5
10
15
20
LBPOS ODI
Score
PLACEBO TENS C-TENS Low-TENS PNT
† Significantly different from Placebo TENS, P<0.05.
LBPOS: Low Back Pain Outcome Scale
ODI: Oswestry Disability Index
-treatment score – Pre-treatment score
†
†
†
†
†
†
Fig. 2. Comparison of improvements in the functional disability scores of the groups.
In our study we found that PNT was more effective
than C-TENS and Low-TENS in decreasing activity
pain whereas there was no difference in current pain.
Activity may induce the pain, and pain at rest eventually
ensues. It’s expected to find, relief of activity pain was
seen at first by the treatment. In this study PNT was
more effective than TENS in providing early relief of
activity pain, which gave it superiority. Activity pain
is a major causative factor in disability of low back
pain patient, and may cause to physical, functional,
social, emotional limitations. A treatment modality
that the more effective in relieving activity pain should
be more better in relieving limitations. In our study we
found that PNT was more effective than C-TENS and
Low-TENS in both relieving activity pain and relieving
limitations of emotional role, increasing vitality and
general health perception.
Previous studies comparing the use of PNT and
TENS in the management of sciatica or low back pain
demonstrated that both PNT and TENS were significantly
more effective than the sham treatments in decreasing
VAS pain scores and improving physical ac132
O. Topuz et al. / Efficacy of TENS and PNT in chronic low back pain
-30
-20
-10
0
10
20
30
40
50
PF SF RP RE MH VT BP GH
Score
PLACEBO TENS C-TENS Low-TENS PNT
† Significantly different from
Significantly different from
Placebo TENS, P<0.05.
PF: Physical function, SF: Social functioning, RP: Physical role limitations, RE: Emotional role
limitations, MH : General mental health, VT: Vitality, BP : Bodily pain, GH: General health perception
-treatment score – Pre-treatment score
†
†
†
†
+
†
†
†
†
†
† †
†
†+ †
†+
†+
†+
†
†
†
†
†
†
+
Fig. 3. Comparison of improvements in the scores of the health quality components of the groups.
tivity. However PNT produced greater improvement
than TENS. In these studies, TENS was administered
only using a stimulation frequency of 4 Hz [7–9,12].
In our study PNT was more effective than both high
frequency (80 Hz) and low frequency (4 Hz) TENS in
providing relief of activity pain and in improving some
component (general health, vitality and emotional role
limitation) of health quality. On the other hand, Hsieh
et al. [13] reported that a simple one-shot treatment
using PNT or TENS is found to be effective in immediate
pain relief in low back pain patients. One shot
TENS treatment may be recommended due to the rarity
of side effects and its convenient application. Weiner
et al. [22] compared the efficacy of PNT plus physical
therapy and sham PNT plus physical therapy in older
patients with chronic low back pain. It was concluded
that PNT may be a promising treatment modality in
chronic low back pain, as demonstrated by reduction in
pain intensity and self reported disability, and improvement
in mood, life control, and physical performance.
In another study PNT improved pain, physical activity,
sleep and disability inpatients with chronic and severe
low back pain [18].
Neurophysiologic studies in animal models support
that the treatment outcomes could largely depend on
TENS parameters [10,19]. In review conducted by J.G.
Gadsby [5] it was concluded that, in chronic low- back
pain patients, conventional TENS and low frequency
TENS appear to reduce pain and improve the range
of movement as compared to placebo at least in the
short term. In our study, TENS modalities were significantly
more effective than placebo TENS, and improvements
did not differ between the conventional and
low-frequency TENS. It has been suggested that the
effect of TENS is due to a placebo effect [15] because
placebo TENS has been shown to relieve pain relative
to a control group receiving no therapy [14]. In our
study, significant pain relief was not shown after the
placebo TENS. The study by Cheing et al. [3] showed
that TENS but not placebo stimulation significantly reduced
chronic clinical low back pain.
The major limitations in the study design includes
(1) potential bias because of inability to blind the investigator
to the treatment modality. (2) the absence
of placebo PNT group. A kind of placebo acupuncture
needle has recently been invented. It is shortened after
its blunt tip touches the skin, and a pricking sensation
is felt by the patient [20]. In our study as we didn’t
use such a needle, we didn’t have the placebo PNT
group. Additionally this study doesn’t provide information
about long-term effectiveness of TENS modalities
and PNT.
5. Conclussion
This study provides evidence for the short-term effectiveness
of conventional or low frequency TENS
treatments and percutaneous neuromodulation therapy
(PNT) on pain, functional disability and quality of life
O. Topuz et al. / Efficacy of TENS and PNT in chronic low back pain 133
in chronic lowback pain. Additionally therewas no difference
between conventional or low-frequency application
for TENS. PNT was more effective than TENS
in providing early relief of activity pain and in improving
some component (general health, vitality and emotional
role limitation) of health quality. Future studies
need to evaluate the long-term effects in chronic low
back pain.
References
[1] A.T. Beck, R.A. Steer and M.G. Garbin, Psychometric properties
of the Beck Depression Inventory: Twenty-five years of
evaluation, Clin Psychol Rev 8 (1988), 77–100.
[2] L. Brosseau, S. Milne, V. Robinson, S. Marchand, B. Shea, G.
Wells and P. Tugwell, Efficacy of the transcutaneous electrical
nerve stimulation for the treatment of chronic low back pain:
a meta-analysis, Spine 27(6) (15 Mar. 2002), 596–603.
[3] G.L. Cheing and C.W. Hui-Chan, Transcutaneous electrical
nerve stimulation: nonparallel antinociceptive effects on
chronic clinical pain and acute experimental pain, Arch Phys
Med Rehabil 80(3) (1999), 305–312.
[4] J.C.T. Fairbank, J. Couper, J.B. Davies et al., The Oswestry
low back pain disability questionnaire, Physiotherapy 66
(1980), 271–273.
[5] J.G. Gadsby and M.W. Flowerdew, Transcutaneous electrical
nerve stimulation and acupuncture-like transcutaneous electrical
nerve stimulation for chronic low back pain, Cochrane
Database Syst Rev (2) (2000), CD000210.
[6] M.E. Geisser, R.S. Roth, M.E. Theisen, M.E. Robinson and
J.L. Riley, Negative affect, self-report of depressive symptoms,
and clinical depression: relation to the experience of chronic
pain, Clin J Pain 16(2) (Jun. 2000), 110–120.
[7] E.S. Ghoname, W.F. Craig, P.F. White, H.E. Ahmed, M.A.
Hamza, N.M. Gajraj, A.S. Vakharia and C.E. Noe, The effect
of stimulus frequency on the analgesic response to percutaneous
electrical nerve stimulation in patients with chronic low
back pain, Anesth Analg 88(4) (Apr. 1999), 841–846.
[8] E.A. Ghoname, W.F. Craig, P.F. White, H.E. Ahmed, M.A.
Hamza, B.N. Henderson, N.M. Gajraj, P.J. Huber and R.J.
Gatchel, Percutaneous electrical nerve stimulation for low
back pain: a randomized crossover study, JAMA 281(9) (Mar.
1999), 818–823.
[9] E.A. Ghoname, P.F. White, H.E. Ahmed, M.A. Hamza, W.F.
Craig and C.E. Noe, Percutaneous electrical nerve stimulation:
an alternative to TENS in the management of sciatica, Pain
83(2) (Nov. 1999), 193–199.
[10] P. Gopalkrishnan and K.A. Sluka, Effect of varying frequency,
intensity, and pulse duration of transcutaneous electrical nerve
stimulation on primary hyperalgesia in inflamed rats, Arch
Phys Med Rehabil 81 (2000), 984–990.
[11] C.G. Greenough and R.D. Fraser, Assessment of outcome in
patients with low-back pain, Spine 17 (1992), 36–41.
[12] M.A. Hamza, E.A. Ghoname, P.F. White, W.F. Craig, H.E.
Ahmed, N.M. Gajraj, A.S. Vakharia and C.E. Noe, Effect of
the duration of electrical stimulation on the analgesic response
in patients with low back pain, Anesthesiology 91(6) (Dec.
1999), 1622–1627.
[13] R.L. Hsieh and W.C. Lee, One-shot percutaneous electrical
nerve stimulation vs. transcutaneous electrical nerve stimulation
for low back pain: comparison of therapeutic effects, Am
J Phys Med Rehabil 81(11) (Nov. 2002), 838–843.
[14] J.E. Jensen, R.R. Conn, G. Hazelrigg et al., The use of transcutaneous
neural stimulation and isokinetic testing in arthroscopic
knee surgery, Am J Sports Med 13 (1985), 27–33.
[15] A.M. Mengshoel, Physiotherapy and the placebo effect, Phys
Ther Rev 5 (2000), 161–165.
[16] J. Mysiw and R.D. Jackson, Electrical stimulation, in: Physical
Medicine and Rehabilitation, R.L. Braddom, ed., Philadelphia,
WB Saunders, 1996, pp. 84–85.
[17] D.M. Novy and D.V. Nelson, What does the Beck Depression
Inventory measure in chronic pain? A Reappraisal, Pain 61(2)
(1995), 261–270.
[18] R. Seroussi, B.E. Gliner, E. Steinintz, S. Schmitt, R. Gamburd
and A.D. Firlik, Effectiveness of Percutaneous Neuromodulation
Therapy (PNT) for Patients with Chronic and Severe Low
Back Pain Study, Pain Practice 3(1) (2003), 22–30.
[19] K.A. Sluka, M.A. Judge, M.M. McColley et al., Low frequency
TENS is less effective than high frequency TENS
at reducing inflammation-induced hyperalgesia in morphinetolerant
rats, Eur J Pain 4 (2000), 185–193.
[20] K. Streitberger and J. Kleinhenz, Introducing a placebo needle
into acupuncture research, Lancet 352 (1998), 364–365.
[21] J.E.Ware and C.D. Sherbourne, The MOS 36-item short form
health survey (SF-36): I. Conceptual framework and item
selection, Med Care 30 (1992), 473–483.
[22] D.K.Weiner, T.E. Rudy, R.M. Glick, J.R. Boston, S.J. Lieber,
L.A. Morrowand S. Taylor, Efficacy of percutaneous electrical
nerve stimulation for the treatment of chronic low back pain in
older adults, J Am Geriatr Soc 51(5) (May, 2003), 599–608.
[23] P.F. White, S. Li and J.W. Chiu, Electroanalgesia: Its Role
in Acute and Chronic Pain Management, Anesth Analg 92
(2001), 483–487.