Mirror therapy for pain?

Posted on December 22, 2011


Photo: Alamy (via The Guardian)

Dateline: 15 November 2011 // Posted by: Kaitlin Hanley
SourceLos Angeles Times; Huffington Post; Daily Mail; The Guardian

Story: “Optical illusion dampens arthritis pain”

Summary: A new study reported at the Society for Neuroscience’s annual conference suggests that mirror therapy, often used as treatment for those who have had an amputation, can also be effective in treating arthritis.  The study was conducted by the lab of V.S. Ramachandran, a neuroscientist whose lab is located at UC San Diego in California.  The findings were presented by neuroscientist Laura Case in Washington.

The therapy, when used for an amputee, requires the patient to sit in front of a mirrored box with two compartments.  The patient extends both limbs, placing the healthy one in the section with the mirror and the amputated one into the other.  Moving the healthy limb and perceiving the same movement in the mirror where the amputated limb should rest, the patient believes the missing limb to be moving and performing normally.  Though this is not the case, the mirror tricks the mind and unclenches the phantom limb.

This therapy, when applied to arthritis, is slightly altered by the researcher extending his or her hand over the patient’s in the mirrored box.  The theory is that when the patient observes the researcher’s young hand moving without pain or difficulty in conjunction with his or her own hand, he or she feels less pain—an average of 1.5 points lower on a pain scale of one to ten.  The study reports that the patients felt even less pain or difficulty when the researcher’s hand held objects in the mirror.  The findings are based on research obtained through observing eight participants and their reports on pain level.

Laura Case and her fellow researchers are currently testing the therapy on a grander scale, but the article positively concludes that mirror-therapy is promising and can provide a treatment for arthritis that is “non-invasive, safe and relatively cheap,” unlike the medication available now.

Why is this PseudoNews? Mirror-box therapy is still a type of treatment in its trial stages as reported by a number of sources and even by the LA Times article itself at the end, though quite briefly and rather played down.  The entire basis of mirror-box therapy relies on tricking the brain into perceiving something that is not actually present.  For such therapy to work, however, the participant certainly must entertain some hope of success.  Otherwise, deceiving the brain to dispel logic probably would not be possible.

Studying the effectiveness of mirror-box therapy relies solely on the testimonies of the participants in reporting their pain levels.  However, these determinations are not only subjective, but can vastly vary in degree.  Imagine one patient’s most painful circumstance being arthritis while another one has suffered through much more traumatic painful situations, like severe burns or a terrible car crash.  Obviously, both would perceive pain differently, thus influencing their pain ratings.

In addition, the study reports mirror therapy to be a more healthy and effective treatment for arthritis in comparison to “non-steroidal anti-inflammatory drugs, which come with a long list of short-and long-term risks.”  This claim in itself is severely misleading, and lacks evidence of long-term results.  Actually, studies of mirror therapy have failed to observe its long-term effectiveness not just in arthritis relief, but in amputation and complex regional pain syndrome treatment.  Thus, how can mirror-box therapy be a proposed alternative to chemical medication if its enduring effect remains unknown in even its established therapeutic disciplines?

What features of pseudoscience are on show? To begin, the entire basis of the research in this study relies on anecdotal evidence, or, in other words, on the personal experiences related by the participants.  Anecdotal evidence has a dangerous tendency to be subjective and thus, given the eight person sample size of the experiment, these results are possibly very misleading.  As previously explained, one person’s significant reduction in pain can represent another’s minor relief depending upon pain sensitivity.  As there is no way to scientifically measure a person’s specific reduction in pain, anecdotal evidence such as presented in the mirror-therapy study poses a major outlet for pseudoscience.

Directly related to the issue of anecdotal evidence is that of vague measurement.  Since the study only observed eight participants, it would not be beyond capability to include the findings in each case in brief.  However, the article merely reports, rather indistinctly, that “when asked about their hands’ level of pain after the exercise, subjects rated their pain, on average, 1.5 points lower, on a scale of 1 to 10 […] Some had a 3-point reduction.”  The article does not provide exactly how many participants reported these results, and consequently it is possible to conclude that by “some” the study could mean just two participants experienced pain relief.

The article may be guilty of argument from authority by disproportionately emphasizieng the importance of key researcher Laura Case, instead of focusing on the study as a group effort.  She is referred to five times throughout the article, given  space in the writing for direct quotes, and it is only by the end do we learn she was working alongside other colleagues on the testing of mirror therapy on arthritis sufferers.

Finally, though stating that such mirror-based treatment must still be tested on a larger group of arthritis patients and perhaps trying to imply its immature status relating to other practices, the article maintains a strong sense of confirmation bias.  It seems that researchers only asked participants if their pain had decreased rather than also inquiring about any potential pain increase.  Findings of decreased pain would of course support their theory that mirror-box therapy helps in the treatment of arthritis, whereas any increase in pain would refute it.

The moral of the story: While this article supporting mirror-box therapy claims that the key to arthritis relief relies upon “a mirror, a healthy body stand-in and a brain,” tricking the mind can hardly constitute permanent results.  Optical illusions are just that—illusions.  Until such illusions find basis in scientific fact, we should not completely dismiss the proven powers of NSAID pain relievers in combating arthritis.