What is Mirror Therapy?

Mirror therapy is a form of intervention where a mirror is used to create a reflective illusion to induce pain relief in the afflicted limb. Mirror therapy was originally proposed as a method to alleviate “phantom limb pain,” which is described as pain in a limb that has been lost. In other words, even though a part of the body is missing, people who have lost a limb reported pain in the missing part. In most cases, this type of phantom pain is reported to occur soon after surgery to remove a limb. About two-thirds of amputees are reported to suffer from chronic phantom limb pain.

History of Mirror Therapy:

Dr. Ramachandran, a neurologist from the University of California, San Diego, invented the mirror therapy. Dr. Ramachandran proposed that the phantom pains were caused by changes in the brain following an amputation. As he said to National Public Radio (NPR), “[It] was based on an idea that there's a complete map of the body's surface on the surface of the brain. So every point on the body's surface has a corresponding point in the brain. Now the curious thing about this map is, even though it's continuous, the face area of the map is right next to the hand area instead of being near the neck where it should be." 

Some simple experiments with blindfolded study subjects proved that the phantom pain originated in the brain. Dr. Ramachandran uses the term “learned paralysis” as the cause of phantom pain in amputees. The region corresponding to the missing limb is still active in the brain, and is deprived of sensory inputs, causing the pain. He says, "The question is: Can you unlearn the pain or paralysis by allowing the brain to send a command to the phantom and have the phantom move — or appear to move — in response to the command. But how do you do that? The guy doesn't have an arm. How do you make the arm appear to move?"

The answer was a “mirror box.”

How does Mirror Therapy work?

1. The mirror is placed parallel to a patient’s nose with the phantom limb on the non-reflective side. 
2. The patient looks at the normal limb on the reflective side and its reflection in the mirror. Anything he does with his normal hand is reflected in the mirror. But, the patient’s brain perceives this as his phantom limb’s movement.
3. The sensory input in the brain region corresponding to the missing limb allows “re-mapping” of the brain, causing the phantom pain to subside over a period of time.

Benefits of Mirror Therapy:

Pain relief for amputees: The reflective illusion provided by mirror therapy has seen success in patients with a hand or arm amputated. The easy to use and inexpensive therapy has been shown in several cases to safely reduce phantom pain in the upper limbs. The reports on pain relief for lower limbs are mixed, ranging from successful treatment to undesirable side effects.

Improvement in Stroke Survivors:  Although originally proposed for phantom pain, mirror therapy has also been used as an additional form of therapy for stroke patients, improving motor function and daily activities while reducing pain.

A randomized control trial conducted on stroke survivors reported improvements in light touch sensitivity defects in such patients. Mirror therapy has also been reported to improve gait in stroke patients.

Peripheral nerve repair: A randomized controlled trial was conducted on patients healing from peripheral nerve repair. An increased effectiveness of mirror therapy compared to late sensory re-education was not apparent, although clinical improvements were observed.

Other benefits: Studies have shown pain relief in other conditions such as complex regional pain syndrome, arthritis, carpal tunnel syndrome, post-surgical rehabilitation, and neuropathic pain. Although the specific mechanism is unknown, the therapy seems to reorganize the motor and sensory cortical networks in the brain so to alleviate pain.

Numerous case studies and anecdotal data indicate the promise of mirror therapy. However, in many cases, there are inconsistencies in the mirror therapy technique, in terms of frequency, duration, etc., which would need optimization. To achieve this, more randomized control trials would be necessary, and the ongoing clinical trials (www.clinicaltrials.gov) should provide answers to many questions.

In summary, the current research on this form of intervention is promising. Investigation into the mechanism of this therapy might provide critical insight and help improve the therapy further.

A word of caution: Please consult with your healthcare provider before initiating alternative therapies. Tell your healthcare provider about any complementary and alternative practices you use. Give them a full picture of what you do to manage your health. This will help your healthcare provider assess your clinical situation better. This will also help them take appropriate clinical measures to assist you. Full disclosure to your healthcare provider will help ensure a coordinated and safe care.

Written by Monique Richards

References:

Ramachandran, V. S., & Rogers-Ramachandran, D. (1996). Synaesthesia in Phantom Limbs Induced with Mirrors. Proceedings of the Royal Society B: Biological Sciences, 263(1369), 377-386.

V.S. Ramachandran's Tales Of The 'Tell-Tale Brain' (n.d.). Retrieved February 15, 2016, from http://www.npr.org/2011/02/14/133026897/v-s-ramachandrans-tales-of-the-tell-tale-brain

Foell, J., Bekrater-Bodmann, R., Diers, M., & Flor, H. (2013). Mirror therapy for phantom limb pain: Brain changes and the role of body representation. EJP European Journal of Pain, 18(5), 729-739.

"Mirror Therapy." - Physiopedia, Universal Access to Physiotherapy Knowledge. Web. 12 Feb. 2016.

Thieme, Holm, Nadine Morkisch, Christian Rietz, Christian Dohle, and Bernhard Borgetto. "The Efficacy of Movement Representation Techniques for Treatment of Limb Pain—A Systematic Review and Meta-Analysis." The Journal of Pain 17.2 (2016): 167-80. Web.

Moseley, Lorimer G., Alberto Gallace, and Charles Spence. "Is Mirror Therapy All It Is Cracked up to Be? Current Evidence and Future Directions." Pain 138.1 (2008): 7-10. Web.

Kim, Sae Young, and Yun Young Kim. "Mirror Therapy for Phantom Limb Pain." The Korean Journal of Pain Korean J Pain 25.4 (2012): 272. Web.

Colomer C, NOé E, Llorens R. “Mirror therapy in chronic stroke survivors with severely impaired upper limb function: a randomized controlled trial” Eur J Phys Rehabil Med (2016) 

Ji, S. G., and M. K. Kim. "The Effects of Mirror Therapy on the Gait of Subacute Stroke Patients: A Randomized Controlled Trial." Clinical Rehabilitation 29.4 (2014): 348-54. Web.

Paula, Mayara H., Rafael I. Barbosa, Alexandre M. Marcolino, Valéria M. C. Elui, Birgitta Rosén, and Marisa C. R. Fonseca. "Early Sensory Re-education of the Hand after Peripheral Nerve Repair Based on Mirror Therapy: A Randomized Controlled Trial." Braz. J. Phys. Ther. Brazilian Journal of Physical Therapy Ahead (2016): 0. Web.