article critque

article critque Project description 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. 5.Are any recommendations made for further research? Give examples. 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: [email protected]. 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.