1 editorial & contents

Percutaneous Electrical Nerve Stimulation –
Electroacupuncture by Another Name?
A Comparative Review.
Summary
Percutaneous electrical nerve stimulation (PENS) investigation to determine whether there was any is a technique that has been described as a ‘novel difference between PENS and EA, and to bring analgesic therapy’. A review was performed of the the matter to the attention of the readership of published literature in order to compare PENS with the author’s knowledge and experience of the use of EA, specifically with regard to the Methods
stimulation parameters, the selection of points, A computerized text word search of PubMed and and the reported efficacy. The conclusion of the the Cochrane database was performed in February review is that PENS is neither different in 2001 using the search term ‘pens’. No other principle nor in practice from EA, and whilst the restrictions were applied to the search. A further term accurately reflects the nature of the text word search of PubMed was performed using treatment, there is no substantial justification for the complete term ‘percutaneous electrical nerve referring to PENS as a novel therapy.
stimulation’. Reading the titles and abstracts identified the references of relevance, and these Keywords
papers were obtained. An analysis of the technique Percutaneous electrical nerve stimulation, of PENS described in the papers was compared with the author’s knowledge and experience of the use of EA, specifically with regard to the Introduction
During a casual search for recent reviews of TENS electrical, the selection of points, and the reported (transcutaneous electrical nerve stimulation) in the Cochrane database, the author happened upon the Results
electrical nerve stimulation) for the first time. At a The PubMed search using the text word ‘pens’ first glance over several abstracts of RCTs of produced 1268 references. The subsequent search using the complete term ‘percutaneous electrical similarity between this ‘novel technique’ and the nerve stimulation’ revealed only 13 references,1-13 more familiar EA (electroacupuncture). The and a search of the Cochrane database did not author was concerned that these papers had been produce any additional ones. Of the 13 references, missed from his routine literature searches for there were seven relevant RCTs,1-7 and one case acupuncture papers, because the abstracts of the series.8 The other references were to letters,10-13 and PENS papers did not include any text beginning one reference was to a systematic review of with the stem ‘acup’ – the search term he had treatments for herpes zoster9 that mentioned one of the PENS trials already identified.5 The ACUPUNCTURE IN MEDICINE 2001;19(1):32-35.
www.medical-acupuncture.co.uk/aimintro.htm Table 1 Papers on Percutaneous Electrical Nerve Stimulation (PENS)
Score – this is the Jadad score, a measure of internal validity, with a maximum possible value of 5.
N – number of subjects in the study. (100ms);2 pulse widths of over 0.5ms are avoided in EA because they are excessively painful, so this is likely to be a reporting error. Biphasic waves tend to be the norm in modern EA, and the pulse widths most frequently used are around All the PENS trials use ‘acupuncture-like 0.2ms; however, these differences are unlikely to needle probes’ inserted to a depth of between 1cm have a significant effect on nerve depolarisation and 4cm. These probes were obtained from a in comparison with the current utilised and the Japanese company that produces acupuncture proximity of the needle electrodes to nerve needles. The needles used were 32G (0.25mm diameter). This is a very commonly used gauge of Frequency – PENS was applied at either 4Hz, needle for EA. Whilst the PENS papers do not 100Hz or at an alternating frequency of 15 and mention manipulation of the needles, other than 30Hz; 4Hz alone was used in two papers,1;2 careful insertion, the stimulation is likely to be 15/30Hz was used exclusively in three papers,4;6;7 indistinguishable from that when performing EA.
and in two papers all three frequencies were applied.3;8 These frequencies are all within the Waveform – In four of the PENS papers a standard range used in EA. One paper claimed a unipolar square wave of 0.5ms duration is benefit of 15/30Hz over either 4 or 100Hz;3 reported to have been used.1;3;4;6 In one paper a biphasic wave is reported to have been used.7 The alternation of frequency, it cannot be said that sciatica trial reportedly used a pulse width of 0.1s these frequencies are superior – any difference ACUPUNCTURE IN MEDICINE 2001;19(1):32-35.
www.medical-acupuncture.co.uk/aimintro.htm may have been due to the alternation rather than there was no significant change in outcome measures for any group in these trials. Sham Amplitude – Where details were given, the PENS papers describe a low output electrical needles at the same sites, and to the same depths generator that produces a current of less than (1cm to 4cm), as used in the PENS procedure, but 25mA. In the application of PENS the authors there was no electrical stimulation of the needles.
state that the intensity of the electrical stimulation These are the only reports of a sham procedure was adjusted to produce the maximum tolerable involving skin penetration, to the author’s sensation without muscle contraction.1 This is knowledge, in which there was no significant likely to correlate with relatively mild EA change in any outcome measure following the stimulation, since muscle contraction is actively sought in the latter, although the intensity perceived by the patient, rather than muscle Discussion
contraction, generally determines the maximum In terms of the sensory stimulus applied to the patient, PENS is certainly a form of EA. The name ‘percutaneous electrical nerve stimulation’ may be novel, and is an accurate description of the The PENS papers describe point selection based technique, but this reviewer feels that describing on dermatomes, though this is used to imply PENS as a ‘novel analgesic therapy’ is not segmental principles, since deeper tissues are supported by the information in the published invariably stimulated. Some of the diagrams in the literature. Whilst traditional Chinese acupuncture papers are not consistent with stimulating the does not use terminology such as dermatomes, intended segments, but these probably represent myotomes, sclerotomes and viscerotomes, it is reporting errors rather than errors in point likely that the majority of traditional acupuncture selection. In the reply to a letter published in treatments involve segmental stimulation, both in Anesthesia and Analgesia,13 White and Craig the approach to pain and to visceral disease.14 (whose names appear on the author list of all the Therefore, whatever the name given to the PENS papers) justify calling PENS a novel treatment, the stimulus to the patient’s nervous therapy, different from EA, because the principles system is likely to be indistinguishable.
of point selection are based on segmental ideas Two of the authors of the PENS papers formed rather than on classical Chinese teachings. Of course, EA is not a classical Chinese technique, as developing an electrical generator for PENS it was invented in the 1950s as an alternative to therapy.15 If such a device gains FDA approval, surgical anaesthesia, and whilst classical points they expect to receive direct financial benefits.15 are used, local segmental needling is also This reviewer was able to mimic the stimulation commonly applied. Moreover, segmental EA has parameters described in the PENS papers with a commercially available EA device (Cefar Acus Acupuncture Society courses for at least the last II), with the exception of the pulse width – a maximum pulse width of 0.45ms can be produced with the Acus II, rather than the 0.5ms described in the PENS papers. With two needles inserted The active intervention proved significantly bilaterally in tibialis anterior, an alternating superior to the control in all seven RCTs of frequency of 15/30Hz was applied with a bipolar PENS.1-7 Sham PENS was used as a control in six square wave and a pulse width of 0.45ms. Robust of these trials.1-4;6;7 When treated with sham PENS muscle contractions were produced without ACUPUNCTURE IN MEDICINE 2001;19(1):32-35.
www.medical-acupuncture.co.uk/aimintro.htm discomfort at an amplitude of 3.5mA. This 2. Ghoname EA, White PF, Ahmed HE, Hamza MA, Craig reviewer contends that commercially available EA WF, Noe CE. Percutaneous electrical nerve stimulation: an alternative to TENS in the management of sciatica. Pain devices are likely to offer a sufficient variety of stimulation characteristics for optimal peripheral 3. Ghoname ES, Craig WF, White PF, Ahmed HE, Hamza nerve stimulation, and there is unlikely to be a MA, Gajraj NM et al. The effect of stimulus frequency on the analgesic response to percutaneous electrical nerve The matter of the consistent lack of efficacy of stimulation in patients with chronic low back pain. Anesth sham PENS, a stimulus that equates to standard 4. Hamza MA, Ghoname EA, White PF, Craig WF, Ahmed segmental dry needling, is puzzling. In blinded HE, Gajraj NM et al. Effect of the duration of electrical trials of acupuncture for chronic low back pain, stimulation on the analgesic response in patients with low penetrating controls have been associated with a back pain. Anesthesiology 1999;91(6):1622-7.
50% response rate.16 Sham PENS has not been 5. Ahmed HE, Craig WF, White PF, Ghoname ES, Hamza reported to produce any significant change over MA, Gajraj NM et al. Percutaneous electrical nerve stimulation: an alternative to antiviral drugs for acute time in the published trials to date.
herpes zoster. Anesth Analg 1998;87(4):911-4.
6. Ahmed HE, White PF, Craig WF, Hamza MA, Ghoname consistently positive results for PENS, there is ES, Gajraj NM. Use of percutaneous electrical nerve clearly a need for independent research to confirm stimulation (PENS) in the short- term management of the findings of this group. It is suggested that headache. Headache 2000;40(4):311-5.
7. Hamza MA, White PF, Craig WF, Ghoname ES, Ahmed future trials address the issue of adequate masking, HE, Proctor TJ et al. Percutaneous electrical nerve which appears to have been lacking in the papers stimulation: a novel analgesic therapy for diabetic to date. The term ‘percutaneous electrical nerve neuropathic pain. Diabetes Care 2000;23(3):365-70.
stimulation’ is acceptable for reporting purposes, 8. Ahmed HE, Craig WF, White PF, Huber P. Percutaneous electrical nerve stimulation (PENS): a complementary ‘acupuncture’ is included in the keywords or therapy for the management of pain secondary to bony metastasis. Clin J Pain 1998;14(4):320-3.
abstract of future papers so that they are revealed 9. Alper BS, Lewis PR. Does treatment of acute herpes zoster in the electronic literature searches of relevant prevent or shorten postherpetic neuralgia? J Fam Pract In conclusion, this review finds that PENS is 10. Berkman R. Percutaneous electrical nerve stimulation for neither different in principle nor in practice from treatment of low back pain. JAMA 1999;282(10):941-2.
11. Hyman MH. Percutaneous electrical nerve stimulation for EA, and whilst the term accurately reflects the treatment of low back pain. JAMA 1999;282(10):941-2.
nature of the treatment, there is no substantial 12. Kaplan EA. Percutaneous electrical nerve stimulation for justification for referring to PENS as a ‘novel treatment of low back pain. JAMA 1999;282(10):941-2.
13. Pinsker MC. Percutaneous electrical nerve stimulation or acupuncture. Anesth Analg 1999;89(4):1065.
Acknowledgement
14. Bekkering R, Bussel Rv. Segmental acupuncture. In The author would like to thank Dr Adrian White for his helpful Filshie J, White AR, eds. Medical Acupuncture, A Western scientific approach, pp 225-94. Edinburgh: Churchill Reference List
15. White PF, Craig WF. Percutaneous electrical nerve 1. Ghoname EA, Craig WF, White PF, Ahmed HE, Hamza stimulation for treatment of low back pain (authors’ reply MA, Henderson BN et al. Percutaneous electrical nerve to letters from Berkman, Hyman and Kaplan). JAMA stimulation for low back pain: a randomized crossover study. JAMA 1999;281(9):818-23.
16. Moore RA, McQuay HJ. Bias. Bandolier 2000;7(10):1-5.
ACUPUNCTURE IN MEDICINE 2001;19(1):32-35.
www.medical-acupuncture.co.uk/aimintro.htm Percutaneous electrical nerve stimulation
electroacupuncture by another name? A
comparative review
Acupunct Meddoi: 10.1136/aim.19.1.32 Updated information and services can be found at: References
Email alerting
Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.

Source: http://acupmed.bmjjournals.com/content/19/1/32.full.pdf