***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: & NA ; The  placebo effect of transcutaneous electrical stimulation was studied in 93 patients in a double‐blind cross‐over trial using a genuine stimulator and a placebo machine . Placebo analgesic effects occurred in 32 % of trials , as compared with 48 % for actual stimulation . The placebo  effect of the transcutaneous electrical stimulator is similar to the placebo effect that is noted in other double‐blind studies in which medicationms are used BACKGROUND AND PURPOSE The prescriptive validity of a treatment-oriented extension-mobilization category for patients with low back syndrome ( LBS ) was examined . SUBJECTS Of a total of 39 patients with LBS referred for physical therapy , 24 patients ( 14 male , 10 female ) , aged 14 to 50 years ( means = 31.3 , SD = 11.6 ) , were classified as having signs and symptoms indicating treatment with an extension-mobilization approach .  The remaining subjects were dismissed from the study . Patients in the extension-mobilization category were r and omly assigned to either an experimental ( treatment ) group ( n = 14 ) or a comparison group ( n = 10 ) . METHODS The experimental and comparison group subjects were treated with either mobilization and extension ( a treatment matched to the category ) or a flexion exercise regimen ( an unmatched treatment ) . Outcome was assessed with a modified Oswestry Low Back Pain Question naire administered initially and at 3 and 5 days after initiation of treatment . Data were analyzed with a 2 x 3 ( treatment group x treatment period ) analysis of variance . RESULTS The subjects ' rate of improvement , as indicated by the Oswestry question naire scores , was dependent on the treatment group to which they were assigned . Subjects treated with extension and mobilization positively responded at a faster rate than did those treated with a flexion-oriented program . CONCLUSION AND DISCUSSION This study illustrates that a priori classification of selected patients with LBS into a treatment category of extension and mobilization and subsequently treating the patients accordingly with specified interventions can be an effective approach to conservative management of selected patients Sciatica is a common pain problem and current pharmacologic therapies have proven inadequate for many patients . The objective of this sham-controlled investigation was to compare a novel non-pharmacologic technique , percutaneous electrical nerve stimulation ( PENS ) , to transcutaneous electrical nerve stimulation ( TENS ) in the management of the radicular pain associated with sciatica . Sixty-four consenting patients with sciatica due to lumbar disc herniation were treated with PENS , TENS and sham-PENS according to a r and omized , single-blinded , cross-over study . All patients had been maintained on a stable oral non-opioid analgesic regimen for at least 6 weeks prior to entering the study . Each treatment modality was administered for a period of 30 min three times per week for 3 weeks , with 1 week ' off ' between each modality . Both PENS and TENS treatments were administered using a stimulation frequency of 4 Hz . The pre-treatment assessment included the health status survey short form ( SF-36 ) , as well as visual analog scales ( VAS ) for radicular pain , physical activity and quality of sleep . The pain VAS was also repeated after each treatment session . At the end of each 3-week treatment block , the SF-36 was repeated . After receiving all three treatment modalities , a global assessment question naire was completed . Both PENS ( 42 % ) and TENS ( 23 % ) were significantly more effective than the sham ( 8 % ) treatments in decreasing VAS pain scores . The daily oral analgesic requirements were also significantly reduced compared to the pre-treatment values with PENS ( P<0.01 ) and TENS ( P<0.05 ) . However , PENS was significantly more effective than TENS ( and sham-PENS ) in improving physical activity and quality of sleep . The SF-36 evaluation confirmed the superiority of PENS ( versus TENS and sham-PENS ) with respect to post-treatment functionality . In the overall assessment , 73 % of the patients reported that PENS was the most desirable modality ( versus 21 % for TENS and 6 % for sham-PENS ) . Finally , 71 % of the patients stated that they would be willing to pay extra to receive PENS therapy compared to 22 % and 3 % for TENS and sham-PENS , respectively . In this sham-controlled study , we concluded that PENS was more effective than TENS when administered at a stimulation frequency of 4 Hz in providing short-term pain relief and improved functionality in patients with sciatica Objectives . Newly developed bidirectional modulated sine waves ( BMW ) might provide some derived benefit to patients with low back pain . Pain relief by transcutaneous electric nerve stimulation ( TENS ) with BMWs was tested . Material s and Methods . Analgesic effects of BMWs and conventional bidirectional pulsed waves on chronic back pain in 28 patients were compared , and effects of repeated TENS using BMWs on chronic back pain were investigated in 21 patients by means of a r and omized double-blind , sham-controlled , parallel-group method . Pain intensity was assessed using numerical rating scale ( NRS ) . Results . There was significant immediate reduction in NRS in patients receiving BMWs , and 60 min after treatment compared to sham TENS . Weekly repeated treatments using massage and TENS with BMWs for 5 weeks result ed in a decrease of NRS , but there were no significant differences between the TENS plus massage and sham TENS plus massage groups . Conclusions . This study shows that TENS with BMWs significantly inhibits chronic back pain , and treatment effects are attained within a day . The results also suggest that there were no statistically significant long-term effects of TENS with BMW in the repeated treatment OBJECTIVES To determine the efficacy of a complementary analgesic modality , percutaneous electrical nerve stimulation ( PENS ) , for the treatment of chronic low back pain ( CLBP ) in community-dwelling older adults . DESIGN R and omized , controlled clinical trial . SETTING University of Pittsburgh Pain Evaluation and Treatment Institute . PARTICIPANTS Thirty-four English speaking , community-dwelling adults aged 65 and older with CLBP of at least moderate intensity experienced every day or almost every day . INTERVENTION Subjects were r and omized to receive twice-weekly PENS and physical therapy ( PT ) or sham PENS and physical therapy for 6 weeks . MEASUREMENTS At baseline , immediately after the 6-week intervention period , and 3 months later , the primary outcome measures pain intensity and pain-related disability were assessed . The secondary outcome measures physical performance ( timed chair rise , functional reach , gait speed , static and isoinertial lifting ) , psychosocial factors ( mood , sleep , and life control ) , and cognitive function ( measures of attention , concentration , and mental flexibility ) were also collected . RESULTS Subjects r and omized to PENS plus PT displayed significant reductions in pain intensity measures from pre- to posttreatment ( P < .001 ) , but the sham PENS plus PT group did not ( P = .94 ) . These pain reduction effects were maintained at 3-month follow-up . Similarly , significant reductions in pain-related disability were observed at posttreatment ( P = .002 ) for the PENS plus PT group and were maintained at follow-up , but the sham PENS plus PT group did not show reductions in pain-related disability ( P = .81 ) . Of the secondary outcome measures , psychosocial function , timed chair rise , and isoinertial lifting endurance also improved significantly at posttreatment for the PENS plus PT group , and their improvement was sustained at 3-month follow-up , but the sham PENS plus PT did not display significant changes on these measures after treatment . CONCLUSION This preliminary study suggests that PENS may be a promising treatment modality for community-dwelling older adults with CLBP , as demonstrated by reduction in pain intensity and self-reported disability , and improvement in mood , life control , and physical performance . Larger studies with longer duration of follow-up are needed to vali date these findings and support the use of PENS in clinical practice OBJECTIVE To investigate to what extent a single 60-minute session of transcutaneous electrical nerve stimulation ( TENS ) would modify chronic clinical pain , acute experimental pain , and the flexion reflex evoked in chronic low back pain patients . STUDY DESIGN Thirty young subjects with chronic low back pain were r and omly allocated to two groups , receiving either TENS or placebo stimulation to the lumbosacral region for 60 minutes . The flexion reflex was elicited by an electrical stimulation applied to the subject 's right sole and recorded electromyographically from the biceps femoris and the tibialis anterior muscles . MAIN OUTCOME MEASURES Subjective sensation of low back pain and the electrically induced pain were measured by two separate visual analog scales , termed VAS(LBP ) and VAS(FR ) , respectively . Data obtained before , during , and 60 minutes after TENS and placebo stimulations were analyzed using repeated measures ANOVA . RESULTS The VAS(LBP ) score was significantly reduced to 63.1 % of the prestimulation value after TENS ( p<.001 ) , but the reduction was negligible after placebo stimulation ( to 96.7 % , p = .786 ) . In contrast , no significant change was found in the VASFR score ( p = .666 ) and the flexion reflex area ( p = .062 ) during and after stimulation within each group and between the two groups ( p = .133 for VASFR and p = .215 for flexion reflex area ) . CONCLUSIONS The same TENS protocol had different degrees of antinociceptive influence on chronic and acute pain in chronic low back pain patients & NA ; Transcutaneous electrical nerve stimulation ( TENS ) is a popular form of electrostimulation . Despite an extensive research base , there remains no consensus regarding the parameter selection required to achieve maximal hypoalgesic effects . The aim of this double blind , sham‐controlled study was to investigate the relative hypoalgesic effects of different TENS parameters ( frequency , intensity and stimulation site ) upon experimentally induced mechanical pain . Two hundred and forty participants were recruited in order to provide statistical analysis with 80 % power at & agr;=0.05 . Subjects were r and omised to one of the six TENS groups , a control , and a sham TENS group ( n=30 , 15 males , 15 females , per group ) .  TENS groups differed in their combinations of stimulation ; frequency ( 4 or 110 Hz ) , intensity ( ‘ to tolerance ’ or ‘ strong but comfortable ’ ) and stimulation site ( segmental – over the distribution of the radial nerve or , extrasegmental – over acupuncture point ‘ gall bladder 34 ’ , or a combination of both segmental and extrasegmental ) . Pulse duration was fixed at 200 & mgr;s . Stimulation was delivered for 30 min and subjects were then monitored for a further 30 min . Mechanical pain threshold ( MPT ) was measured using a pressure algometer and taken from the first dorsal interosseous muscle of the dominant h and , ipsilateral to the stimulation site . MPT measures were taken , at baseline , and at 10‐min intervals for 60 min . Difference scores were analysed using repeated measures and one‐way ANOVA and relevant post hoc tests . Low frequency , high intensity , extrasegmental stimulation produced a rapid onset hypoalgesic effect , which increased during the stimulation period ( P<0.0005 control and sham ) and was sustained for 30 min post‐stimulation ( P<0.0005control , P=0.024sham ) . Whilst high frequency , ‘ strong but comfortable ’ intensity , segmental stimulation produced comparable hypoalgesic levels during stimulation , this effect was not sustained post‐stimulation . Stimulation at a combination of the two sites did not produce any greater hypoalgesic effects . These results may have implication s for the clinical use of sensory stimulation BACKGROUND Electrical stimulation of peripheral nerves produces acute analgesic effects . This r and omized , sham-controlled , crossover study was design ed to evaluate the effect of differing duration s of electrical stimulation on the analgesic response to percutaneous electrical nerve stimulation in 75 consenting patients with low back pain . METHODS All patients received electrical stimulation for four different time intervals ( 0 , 15 , 30 , and 45 min ) in a r and om sequence over the course of an 11-week study period . All active percutaneous electrical nerve stimulation treatments were administered using alternating frequencies of 15 and 30 Hz three times per week for 2 consecutive weeks . The pre study assessment s included the health status survey short form question naire and 10-cm visual analog scale scores for pain , physical activity , and quality of sleep , with 0 being the best and 10 being the worst . The pain scoring was repeated 5 - 10 min after each 60-min study session and 24 h after the last treatment session with each of the four methods . The daily oral analgesic requirements were assessed during each of the four treatment blocks . At the end of each 2-week treatment block , the question naire was repeated . RESULTS Electrical stimulation using percutaneously placed needles produced short-term improvements in the visual analog scale pain , physical activity , and quality of sleep scores , and a reduction in the oral analgesic requirements . The 30-min and 45-min duration s of electrical stimulation produced similar hypoalgesic effects ( 48+/-21 % and 46+/-19 % , respectively ) and were significantly more effective than either 15 min ( 21+/-17 % ) or 0 min ( 10+/-11 % ) . The 30- and 
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There was moderate evidence that work status and the use of medical services did not change with treatment .
Multiple physical outcome measures lacked statistically significant improvement relative to placebo .
In general , patients treated with acupuncture-like TENS responded similarly to those treated with conventional TENS .
At this time , the evidence from the small number of placebo-controlled trials does not support the use of TENS in the routine management of chronic LBP .