***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 
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    ***EXAMPLES*** 
    Input: The aim of the present study was to compare the effect of transcutaneous electric nerve stimulation ( TENS ) with the flat occlusal splint in the treatment of temporom and ibular joint ( TMJ ) disk displacement without reduction . Thirty-one patients were included and r and omly selected to be treated 6 weeks with either TENS ( 90 Hz , 30 min , three times/day ) or with a flat occlusal splint ( 24 h/day . Those selected for the TENS group had one electrode placed over the painful TMJ and another electrode over the anterior temporal muscle . The splint group used a conventional flat occlusal splint with cuspid guidance . Both treatment groups visited the clinic once a week . Symptoms and signs were registered before and after treatment . The intensity of pain was recorded with a visual analogue scale ( VAS ) and with an electronic pocket-sized recorder ( Pain-Track ) carried 1 week before and also the last week of treatment for continuous registration of pain . Measured with the VAS , half of the patients treated with splints became pain-free or their TMJ pain improved at least 50 % both at rest and with jaw function compared with only 6 % in the TENS-treated group . With regard to strictly chewing pain , the VAS-registered pain improved in two-thirds of the splint group , compared with 50 % of the TENS group . With the Pain-Track device it was found that in most individuals pain was aggrevated at mealtimes . The conclusion was that flat occlusal splints in several respects are better than TENS in the treatment of symptoms associated with TMJ disk displacement without reduction & 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 & NA ; The effects of transcutaneous electrical nerve stimulation ( TENS ) on myofascial pain and trigger point sensitivity were assessed . Four modes of TENS and a no‐stimulation control were compared in a double‐blind design . Stimulation , carried out for 10 min on 60 subjects ( 12/group ) , showed significant pain reductions with 100 Hz , 250 msec stimulation followed by 100 Hz , 50 msec and then pain suppressor TENS .  No pain reductions were found in the 2 Hz , 250 msec TENS or the control . No significant alteration in myofascial trigger point sensitivity , assessed with the pressure algometer , was found between the groups . The results suggest that high frequency , high intensity TENS is effective in reducing myofascial pain , and that these pain reductions do not reflect changes in local trigger point sensitivity Therapeutic trials often attempt to “ blind ” patient and investigator to the true nature of treatments received , reducing the influences of conscious or subconscious prejudices . In drug trials , this is accomplished with placebo tablets , but blinding in trials of physical treatments is more problematic . This issue arose in a clinical trial of transcutaneous electrical nerve stimulation ( TENS ) for patients with chronic low back pain . Several study design features were incorporated to promote blinding : use of sham TENS units visually identical with real units , exclusion of potential subjects with previous TENS experience , avoidance of a crossover design and use of identical visit frequency , instructions and modifications in electrode placement . Subjects were asked not to discuss treatments with the clinicians who performed outcome assessment s. Both patients and clinicians were asked to guess actual treatment assignments at the trial 's end . Every patient in the true TENS group believed the unit was functioning properly , but the degree of certainty varied . In the sham TENS group , 84 % also believed they had functioning units , but their certainty was significantly less than in the active treatment group . Differences in patient perceptions did not affect compliance , as the two groups had similar dropout rates , appointment compliance , days of TENS use and daily duration of TENS use . Clinicians guessed treatments correctly 61 % of the time ( as opposed to 50 % expected by chance ) , again suggesting partial success in blinding . These efforts at blinding may partly explain the negative trial results for TENS efficacy . We conclude that complete blinding is difficult to achieve because of sensory difference in treatment and unintended communication between patient and examiner . Nonetheless , trials of physical treatments can achieve partial blinding with the techniques described here , and the success of blinding can be assessed with simple questions at study completion Abstract  Variability  in patients ' response to interventions in pain and other clinical setting s is large . Many explanations such as trial methods , environment or culture have been proposed , but this paper sets out to show that the main cause of the variability may be r and om chance , and that if trials are small their estimate of magnitude of effect may be incorrect , simply because of the r and om play of chance . This is highly relevant to the questions of ‘ How large do trials have to be for statistical accuracy ? ’ and ‘ How large do trials have to be for their results to be clinical ly valid ? ’ The true underlying control event rate ( CER ) and experimental event rate ( EER ) were determined from single‐dose acute pain analgesic trials in over 5000 patients . Trial group size required to obtain statistically significant and clinical ly relevant ( 0.95 probability of number‐needed‐to‐treat within ±0.5 of its true value ) results were computed using these values . Ten thous and trials using these CER and EER values were simulated using varying group sizes to investigate the variation due to r and om chance alone . Most common analgesics have EERs in the range 0.4–0.6 and CER of about 0.19 . With such efficacy , to have a 90 % chance of obtaining a statistically significant result in the correct direction requires group sizes in the range 30–60 . For clinical relevance nearly 500 patients are required in each group . Only with an extremely effective drug ( EER>0.8 ) will we be reasonably sure of obtaining a clinical ly relevant NNT with commonly used group sizes of around 40 patients per treatment arm . The simulated trials showed substantial variation in CER and EER , with the probability of obtaining the correct values improving as group size increased . We contend that much of the variability in control and experimental event rates is due to r and om chance alone . Single small trials are unlikely to be correct . If we want to be sure of getting correct ( clinical ly relevant ) results in clinical trials we must study more patients . Credible estimates of clinical efficacy are only likely to come from large trials or from pooling multiple trials of conventional ( small ) size OBJECTIVE Our purpose was to compare the effects of high-intensity transcutaneous electrical nerve stimulation and oral naproxen ( 500 mg ) on intrauterine pressure and menstrual pain . STUDY DESIGN An open , r and omized crossover study was performed on 12 women with primary dysmenorrhea .  Intrauterine pressure was recorded with a microtransducer catheter , and the pain score was assessed by a visual analog scale . RESULTS Before treatment all patients displayed signs of uterine hyperactivity  as judged by a high resting pressure ( 7.5 + /- 0.4 kPa ) , high active pressure ( 24.0 + /- 0.8 kPa ) , and a high frequency of pressure cycles ( 13.3 + /- 0.5 contractions per 0.5 hour ) . Oral administration of naproxen suppressed ( p < 0.01 ) all uterine activity parameters . Treatment with transcutaneous electrical nerve stimulation induced a prompt onset of pain relief in a strictly segmental manner , but there were no significant changes in uterine activity . The pain score was significantly reduced ( p < 0.001 ) from 30 to 60 minutes after treatment with transcutaneous electrical nerve stimulation and from 19 to 120 minutes after naproxen administration . CONCLUSIONS Treatment with transcutaneous electrical nerve stimulation induced a prompt onset of pain relief without any significant changes in uterine activity . Possible mechanisms for the pain relief , decreased uterine ischemia or decreased activity in the pain transmission system at spinal or supraspinal levels , are discussed The purpose of this investigation was to evaluate the long-term course of non-invasively treated chronic headache . A total of 1015 adult patients with primary diagnosis of vascular/migraine or muscle contraction headache participated in the study investigating symptom frequency and severity over a 36 month period after receiving treatment . Treatment consisted of either : relaxation training ( stepwise relaxation/hypnosis/autogenic training/cognitive behavior therapy ) ; biofeedback ( thermal/photoplethysmograph/EMG ) ; micro-electrical therapy ( TENS/Neurotransmitter Modulation ) or multimodal treatment ( combination of any of the above two treatments ) .  Seven hundred and ninety-three patients returned sufficient data to be included in the analysis . Patients were r and omly assigned to treatment groups and received either short term intervention ( 15 or less treatments ) or long term intervention ( greater than 15 treatments ) . Results indicate that all treatment conditions significantly reduced frequency and intensity of cephalalgia . Repeated measure analysis of variance indicated that grouping variables of Biofeedback treatment , symptoms being evidence d less than 2 years and receiving over 15 treatment sessions best predicted successful intervention The analgesic efficacy of various pulse patterns of transcutaneous electrical nerve stimulation ( TENS ) were assessed in 84 normal healthy subjects using the cold pressor pain technique .  Burst , modulation , r and om and continuous TENS all significantly elevated ice pain threshold .  Continuous ( 80 Hz ) TENS produced the greatest mean elevation in threshold but the response to r and om TENS showed the least inter-subject variation . Ice pain tolerance was increased by all modes of TENS , continuous TENS producing the greatest magnitude of response , although these changes did not reach statistical significance . Increasing the size of electrodes reduced the effect of continuous TENS . The clinical implication s of these findings are discussed Acupuncture is one of the oldest healing methods which is used in traditional medicine . In the modern medicine , we are witnessing a renaissance of this ancient treatment applied mainly in the management of chronic pain . A number of modern technological changes are being applied to replace , or modify , the classical needle treatment . Among many modalities used today is the novel addition in Transcutaneous Electrical Nerve Stimulation ( TENS ) called CODETRON which delivers acupuncture-like stimulation in a r and om order . CODETRON was developed by a Canadian Scientist and had been evaluated in a clinical trial in a multidisciplinary pain clinic on patients who came for acupuncture therapy over a period of two years .  Indications , effectiveness and experiences with this form of treatment are presented . In addition , results obtained from a six week double-blind r and omized placebo controlled pilot trial of osteoarthritis of the hip/knee with CODETRON which was conducted later . The results were highly suggestive of the beneficial effect of this nonhabituating mode of therapy and confirmed our initial uncontrolled trial results There is currently no established treatment for intermittent claudication with proven long term benefit . Exercise classes have been shown to improve walking distance .  Chronic electromyostimulation ( CEMS ) a method of stimulating skeletal muscle has effects on normal muscle which may also benefit claudicants . We investigated the effects of one month of CEMS on claudicants in a single blind placebo controlled study . Patients were r and omised to either CEMS ( treatment ) or transcutaneous nerve stimulation ( TENS ) placebo .  The effects of the two modalities were assessed using the conventional measures of claudicating distance ( CD ) , maximum walking distance ( MWD ) , ankle-brachial pressure index ( ABPI ) and pressure recovery time ( PRT ) . Muscle performance was assessed by the fatigue index ( FI ) a technique determining the decrease in ischaemic muscle response to repeated contraction . After 4 weeks treatment the CEMS group showed significant improvements in their median CD ( 88 to 111 ) and MWD ( 118 to 158 ) ; this was not seen in the control group . Muscle performance also increased significantly during the 4 weeks of treatment in the CEMS group but not in the control group . These changes were not maintained after CEMS was stopped . This pilot study suggests that CEMS may well have a role to play in the treatment of intermittent claudication though a number of further studies need to be undertaken Abstract . in this study we describe the use of high‐frequency transcutaneous electrical nerve stimulation ( TENS ) ( 100 Hz ) and low‐frequency TENS ( lf‐TENS ) ( 2 Hz trains ) as compared with placebo‐TENS ( p‐TENS ) in a group of 21 patients suffering from primary dysmenorrhea .  Naloxone , a relatively pure opiate antagonist , was an additional test administered to 6 volunteer patients who had experienced an alleviation of pain with TENS . As will be seen , 14 out of 21 patients receiving high‐frequency TENS ( hf‐TENS )  experienced a pain reduction exceeding 50 % of its original intensity . During lf‐TENS or p‐TENS , only 7 and 5 patients , respectively , obtained pain relief exceeding 50 % . in 4 out of 6 volunteer patients , the relief of pain obtained with lf‐TENS was counteracted by naloxone , whereas the relief experienced with hf‐TENS in the same patients was , in general , unaffected by naloxone We compared the effects of four treatment variables on the pain reduction produced by transcutaneous electrical nerve stimulation and attempted to establish indications for TENS based on patient history and pain evaluation items . Treatment variables were the therapist and the three TENS stimulus characteristics -- pulse width , frequency , and amplitude . We r and omly assigned 192 consecutive adult patients suffering from painful conditions to one of four physical therapists and one of 12 stimulus characteristic combinations . We used a st and ar 
    Output:
    
REVIEW ER 'S CONCLUSIONS The results of this review are inconclusive ; the published trials do not provide information on the stimulation parameters which are most likely to provide optimum pain relief , nor do they answer questions about long-term effectiveness .