Not too long ago, there was a perception by physicians and practitioners that phantom limb pain (PLP) was purely psychological. The perception has begun to change. Today, patients enduring PLP are being treated with the understanding that there is a physical element to their pain.
Due to ongoing questions regarding the mechanisms behind PLP, there are a broad range of treatments that could be as common as a patient taking an over-the-counter pain reliever or as invasive as regional epidurals. The goal is the same – to shut down the receptors that can receive pain.
According to a study co-authored by Steven R. Hanling, MD, MC, assistant professor of anesthesiology for the Uniformed Services University of the Health Sciences School of Medicine and pain fellowship program director at Naval Medical Center San Diego, pre-operative mirror therapy treatment may prevent the development of PLP. According to the study, PLP occurs in as many as 72% of amputees. Mirror therapy has been used to treat PLP but there are no studies that describe the use of pre-operative mirror therapy to prevent the development of PLP, the study noted.
For the study, patients sat on a chair and placed a vertical mirror between their legs and arms. The reflection visually tricks the brain into thinking that the patient’s phantom limbs can move, which can lead to dramatic relief of their PLP. The four participants in the study pre-operatively observed the unaffected leg reflected in the mirror during 30-minute sessions, 2 weeks prior to their amputation. All four participants completed five to six mirror therapy sessions supervised by a physical therapist, according to the study.
“One theory is that in patients with nerve injury prior to amputation, a disconnect occurs between motor commands from the brain to the injured limb,” Hanling explained to O&P Business News. “Because there is a lack of visual feedback, the brain starts to ignore the limb and after surgery, the patient may not be able to control his or her phantom limb. This is important because these paralyzed phantom limbs are associated with PLP. By providing visual feedback via the mirror, we reconnect the brain and they tend to regain control of their phantom limb. When that happens, there appears to be a reduction in phantom pain.”
According to the study, at 4 weeks post-amputation, one patient reported no residual limb pain or PLP, two patients reported mild residual limb pain and mild PLP and one patient reported moderate residual limb pain with brief episodes of PLP.
“What was unique and hopeful for further success is that all of these patients were at high risk for PLP,” Hanling said. “They were in a prolonged recovery period and often experienced significant levels of chronic pain. There is an association that if you have pre-amputation pain, you have a higher instance of PLP.”
The study noted that the four patients experienced prolonged courses of limb salvage and chronic pain before their amputation but experienced only brief bouts of PLP after surgery. According to Hanling, after 4 weeks post-amputation, the four patients were 100% compliant with physical therapy and were able to walk a community distance, which is typically described as 1000 feet unassisted with a prosthesis. The smooth transition to independent care by the participants in the study should not be overlooked, according to Hanling.
“All of the participants were able to meet functional outcomes,” Hanling said. “That is the key. Studies have to start focusing on functional outcomes. Pain is important in and of itself, but it is more important to see how reductions in pain affect our patient’s ability to transition to independent care. That should be the focus.”
He also plans on starting a large scale, multi-center study.
“Our plan is to not only try the therapy as far as pain outcomes, but to also perform brain imaging studies to see if we can actually find the link between the therapy and what is happening in the brain,” Hanling said. — by Anthony Calabro
The options for using mirror therapy to treat pain are expanding. In addition to treating amputation-related phantom pain, mirror therapy has been used to successfully treat complex regional pain syndrome, another pain condition that occurs in intact limbs. Moreover, recent research has focused on the use of mirror therapy for post-stroke pain and rehabilitation.
Hanling’s research suggests that the timing of mirror therapy is a critical variable to consider. Not only may phantom pain be prevented for persons with anticipated amputation, but one wonders whether the mirror therapy may also help reorganize brain pathways for the pain conditions that may exist in the limb prior to amputation. This group’s planned functional magnetic resonance imaging studies may speak to this question.
The applications of mirror therapy are expanding and so is our understanding of the simplicity of the treatment itself. Mirror therapy is described in the scientific literature as being therapist-guided and often involves a specific set of mirror exercises. However, my research suggests that home-based, self-delivered mirror treatment is effective for phantom pain. With minimal instruction, patients with phantom pain can treat themselves at home with a mirror purchased from a thrift store. The benefits of home-based self-delivered mirror treatment include low or no cost pain care, reduced medical and physical therapy visits and reduced travel burden. Such benefits are important, particularly for persons in developing countries who have limited access to pain care.
Mirror therapy is proving to be a cost-effective treatment for phantom pain, and early data suggest it may also be helpful for treating other conditions. The simplicity of mirror therapy stands to improve access to pain care for patients around the world.
— Beth Darnall, PhD
Oregon Health and Science University department of anesthesiology and peri-operative medicine