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[escepticos] RV: Scientific Evidence for Acupunctural Analgesia

Os reenvio esto que anda por la lista de la JREF... ya que hablabais de
acupuntura y demas...


(y hasta dentro de una semana)

-----Original Message-----
De: Richard O. Brown <robrown en ucsd.edu>
Para: wizards-star-list en ssr.com <wizards-star-list en ssr.com>
Fecha: lunes 19 de enero de 1998 9:06
Asunto: Re: Scientific Evidence for Acupunctural Analgesia

>Acupunctural Analgesia offers an interesting "Open-Mindedness" test for
>The traditional theories of acupuncture involve the flows of Qi (spirits)
>through the "meridians", with astrological influences.  Many or most of the
>claimed medical effects of acupuncture seem preposterous, and have never
>been properly tested.  So it's tempting to just dismiss ALL of acupuncture
>as pseudoscientific quackery.
>BUT:  Good, properly controlled, double-blind studies, and current
>neurophysiological theories of pain, clearly support Acupunctural Analgesia
>as an objective physiological effect.  Various related methods of
>"Stimulation-Induced Analgesia" have now been incorporated into mainstream
>medical science, and these have provided many people enormous relief from
>I suggest it behooves skeptics to accept the limited but proven validity of
>acupunctural analgesia, while cognizant that this doesn't generalize to any
>of the other claims made for acupuncture and Qi Gong- which span the gamut
>from the mundane to the clearly supernatural.  Twiddled needles produce
>analgesia whether you believe in Qi Gong or neurophysiology, just as the
>sun still rises whether you believe in Apollo's chariot or gravity.
>(This also brings up important questions about just what constitutes a
>"Claim of the Paranormal".  Acupunctural analgesia may have sounded
>paranormal in 1972, but now it's mainstream medical science!)
>For anyone interested, I'm appending a brief outline of scientific evidence
>for the effectiveness of acupunctural analgesia, and why I believe Clark
>and Yang's 1974 experiment does not seriously challenge its validity.
>At 08:17 AM 1/14/98 -0800, Robert F Dippner wrote:
>>Last month someone had asked if there was any scientific evidence  for
>>the effectiveness of acupuncture. I think this question was answered
>>almost 25 years ago and the answer has been ignored.
>>W. C. Clark and  J,C. Yang wrote an article that appeared in the June 7,
>>1974  issue of Science Vol. 184. The title was "Acupunctural Analgesia?
>>Evaluation by Signal Detection Theory.
>>Their conclusion was that acupuncture makes no sensory (physiological)
>>change but rather causes the subject to raise their criterion for pain in
>>response to the expectation that acupuncture works.
>> Bob Dippner
>(1)  As was already posted on this thread [and did I detect a touch of
>ridicule?], on November 5 1997 "A consensus panel convened by the National
>Institutes of Health (NIH) today concluded there is clear evidence that
>needle acupuncture treatment is effective for postoperative and
>chemotherapy nausea and vomiting, nausea of pregnancy, and postoperative
>dental pain."  (The panel chairman, David Ramsay, was once my postdoctoral
>advisor at UCSF- and I can assure you he is a rational, clear-thinking
>physiologist, not prone to New-Age nonsense!)  I hope skeptics will at
>least give the benefit of the doubt to the Scientific Method, and take the
>time to read and evaluate this report before bemoaning its implications!
>(2)  Another excellent source is the encyclopedic "Textbook of Pain", 3rd
>edition (1994), edited by Wall and Melzack.  In Chapter 64, "Folk medicine
>and the sensory modulation of pain", Melzack reviews evidence supporting
>acupunctural analgesia, such as controlled studies on humans and other
>animals, and objective neuropharmacological and neurophysiological studies
>of acupuncture.  He also notes that acupuncture's traditional needling
>methods and points of application are unnecessary, and concludes that
>"Acupuncture is not a magical procedure, but only one of many ways to
>produce analgesia by an intense sensory input which may be labeled
>generally "hyperstimulation analgesia".
>(3)  The generally accepted theory holds that pain is not simply
>transmitted directly to the brain by "labeled-line" pain nerve fibers, but
>involves network interactions among different types of sensory nerve
>fibers.  Very roughly, acupuncture and related methods are thought to work
>by strongly activating certain of these sensory nerve fibers, which then
>inhibit the transmission of pain signals from other sensory nerve fibers.
>The most effective points for acupunctural analgesia seem to correspond
>appropriately with peripheral nerves (not Qi meridians!), and the analgesic
>effects of acupuncture can be eliminated by blocking its presumed neural
>pathways in various ways.
>(4)  Chapter 63, by Woolf & Thompson, discusses other modern methods and
>theory of "stimulation-induced analgesia".  They suggest that "The ability
>of a clinician to reduce pain in a patient by exploiting the patient's own
>in-built neurobiological mechanisms must surely rate as one of the great
>achievements of contemporary medical science."
>(5)  On Signal-Detection Studies of Pain:
>Signal-Detection Theory was developed to objectively measure both the
>absolute sensory sensitivity (d') and the response biases of observers, in
>detecting the presence or absence of specified physical signals.  But its
>application to quantifying pain requires problematic assumptions which seem
>to blur the important distinction between analgesia (loss of pain) and
>anaesthesia (loss of sensation).  The Signal-Detection experiments assumed
>that analgesia implies a reduced ability to discriminate physical stimuli.
>Criticisms of Clark and Yang's 1974 paper, and their response, were
>published in a subsequent issue of Science (4 july 1975, vol. 189, pp
>In any event, although Clark and Yang found no reduction of d' by
>acupuncture, two other groups using Signal-Detection methods reported that
>acupuncture DID reduce d' (Chapman et al. 1975, 1976, 1977; Lloyd & Wagner
>1976).  So even if one accepts the validity of Signal-Detection measures of
>acupunctural analgesia, it seems inappropriate to "cherry-pick" just Clark
>& Yang's paper, while ignoring the subsequent contradictory results.