Effectiveness of Mirror Box Therapy on Phantom Limb Pain - Essay Example

Effectiveness of Mirror Box Therapy on Phantom Limb Pain Summary Almost immediately after amputation, between 90 and 98% of all patients experience a vivid phantom. Phantom limb is most commonly reported after amputation of an arm or leg. Very elaborate sensory memories can re-emerge in the phantom as a result deafferantation. The vividness of the phantom appears to depend on cortical magnification and vivid experience with the lost limb. Motor imagery in the physical therapy practice has been a tool for treatment of such pains. This uses a mirror-box to create a mental representation of the movement without actually any body movement. There have been many studies in this area showing the effectiveness of mirror-box therapy in case of painful phantom limbs. This work studies the relevant published literatures and reviews them in a systemic fashion to arrive at a finding that immediately after the amputation, the sensory cortex organizes itself, but retains the amputated limb’s presentation within the brain. Visual illusions created by a mirror-box can use that illusory phenomenon to psychologically manipulate the patients so they can get rid of the pain. The studies, although establish the effectiveness of such therapy in neuro-rehabilitation do not point at the possible mechanisms for such, and this author concludes that further research is mandated for establishing a cause-and-effect relationship. Introduction: After amputation in the clinical practice, most patients complain of sensation that seems to emanate from the amputated body part. This effect is known as phantom sensation. In some patients, this sensation can be very intensely painful. Although little is known about the operant mechanisms of such phenomena, it is now known that nociceptor function is dynamic and may be altered following surgical tissue injury, and that may contribute to persistent pain. The perception of pain in such situations is not a predictable neurophysiological mechanism where stimuli are always transmitted and processed in an identical manner. Therefore, the central nervous system pain perception mechanism demonstrates a great deal of plasticity. The study of phantom limbs has received tremendous impetus from recent studies linking the changes in cortical topography with perceptual experience. It has long been acknowledged that multiple sensory stimuli contribute to the conscious awareness of the body. Those who have limb amputation will have abnormal body awareness. Many studies have been undertaken to evaluate the effects of mirrorbox therapy as a model of neuro-rehabilitation. These aim to study and evaluate the central nervous system schema and updates after the amputation. Basically, the mirror box therapy aims at creating a mirror visual illusion. These patients actually view their intact limbs in a mirror, and this would create an illusion of their amputated limb. This also allows an opportunity for the therapist to create an effect of combined visual and movement-related stimuli during active voluntary movement Melzack, R., 1995, pp. 73-82). Mirrorbox Therapy: This therapy is based on visual illusion created by mirror-box. In case of upper extremity amputation, the amputee is required to place both the upper extremities in an open box containing a mirror partition. Then the amputee views the intact hand and its mirror image to create the illusion of two intact hands. The side of the box that contains the amputated limb is covered with a towel. The three phases of this process are as follows. In phase I, subjects view the intact limb and its reflection. They will then be asked to move the intact hand. These movements may be rotating it, making a fist, or wiggling the fingers. The reflection in the mirror would be appreciated and imagined as moving the phantom hand while continuing to view the intact hand and its reflections. The subjects will be asked to describe the location, quality, position, and intensity of any PLA or PLA that might have arisen at rest and during movement. In phase II, the subject would view the intact limb and its reflection while tactile stimuli are applied to the intact hand, the residual limb, and simultaneously to various locations on the distal residual limb and identical locations on the intact limb. These would have created three conditions of congruent and conflicting visual illusion and tactile input. The subject would receive tactile input from the intact hand and would have watched the stimulus touch the intact hand and its reflection in the mirror. In the case of amputated limb, the subject would receive tactile stimulation of the amputated limb, but would not see the stimulus touching it because the mirror would block the view of the residual limb. Evoked sensations that would be perceived dually both in the missing limb and the intact side would create an illusion of bilateral stimulation of two intact upper extremities in the mirror box Ramachandran, V.S., Stewart, M., and Rogers-Ramachandran, D.C., 1992, pp. 583-586). Neurological Context: The characteristic feature of adult primate brain is the existence of multiplicity of specialized areas including distinct topographically organized maps concerned with different sense modalities. It has been established beyond reasonable doubts that in the visual domain alone, there are over 30 distinct areas that contain either partial or complete maps of the visual field. It has been shown that sensory maps can change or develop newly in the adult brain, and this had been largely responsible for resurgence of interest in the clinical phenomena of phantom limbs. This is experimental, but the context is based on facts that new connections emerge in the human brain and information from different sensory modules, such as, touch, proprioception, and vision interact. Numerous studies on phantom limbs also provide an understanding about how the brain constructs a body image, and how this image is continuously updated in response to changing sensory inputs. The patients with phantom limb experience an amputated extremity to be still present and in some cases would also experience pain and cramping in the missing limb, designating dissociation between the felt position of the limb and its actual position. The patients also complain frequently that the phantom is painful. The incidence of severe pain in clinical practice is such that it is, indeed, a major clinical problem. This may persist even 25 years after the loss of the limb. This suggests that the central representation of the limb survives after amputation and is largely responsible for the phantom. Understanding the nature and origin of this representation and its neural basis and the extent to which it can be modified by sensory experience is the major concern of this work. This work, therefore, poses to extract the fundamental insights into the functional organization of the normal human brain in the backdrop of the phenomenon of a phantom limb and to review the experimental studies that demonstrate how the normal human adult brains can serve as perceptual markers for tracking neural plasticity in the adult brain (Birbaumer, N., Flor, H., Lutzenberger, W., and Elbert, T., 1995, pp. 331-344). Literature Review Strategy: This author has decided to review 5 contemporary literatures on mirror-box therapy that would quantitatively experiment the effects of such on phantom limb pain. For this purpose, this author decided to explore relevant study literature in different databases, both electronic and non-electronic. Local library database index was searched for literature with the key words, phantom limb, amputation, phantom limb pain, neuro-rehabilitation, mirror-box therapy, and effectiveness. This delivered two studies. Electronic databases were searched in the Internet with advanced search options in websites Embase, Chochrane, Google Scholar, Infotrieve, Highwire Press, British Medical Journal, Pubmed, Oxford University Press, ScienceDirect, Elsevier, and UTSA Library with the same keywords with further intensifying the search with effectiveness of mirror-box therapy in phantom limb pain. This resulted in three literatures. A total of these 5 literatures would be reviewed in the following sections. Literature Review: The first article reviewed is titled, “The effect of tactile and visual sensory inputs on phantom limb awareness” by Judith P. Hunter, Joel Katz, and Karen D. Davis, published in Brain, Volume 126, pages 579 to 589. This study systemically evaluates the effects of sensory inputs on phantom limb awareness shortly after upper limb amputations. The locations, qualities, and intensities of spontaneous and tactile-evoked phantom sensations and awareness were assessed in 13 amputees who were referred sequentially for their initial postoperative rehabilitation. There have been no systemic studies of how vision and sensorimotor inputs interact to change the perception of evoked versus spontaneous phantom limb sensation and phantom limb awareness. This study is designed to determine the prevalence of spontaneous and evoked phantom limb sensation in a non-selected group of persons shortly after unilateral upper extremity amputation and secondly to investigate the effects of altering tactile and visual (real and illusory) inputs on spontaneous and evoked phantom limb sensation and phantom limb awareness. After ethical clearance, all the participants were tested in three visual conditions with eyes open, with eyes closed, and while viewing the intact hand in the mirror. This study found that vision had a powerful effect on tactile-evoked dual percepts. This means seeing the actual stimulation served typically as a reality check, negating the percept that the stimulus had been applied to the missing body part. This study suggests that the effect of normal visual input could also reflect the conflicting versus congruent nature of the tactile and visual sensory inputs. This study revealed that the subjects were well aware of the location of the stimulus to the face or to the stump when tested in the eyes-open condition, that is, the visual information conflicted with the referred phantom sensation. The dual percept was not perceived in the eyes open condition, thus illustrating visual dominance over touch. The authors conclude that spontaneous and evoked phantom sensations are two separate phantom phenomena. The evoked dual percepts were less common and behaved in a different manner from spontaneous phantom awareness (Hunter, J.P., Katz, J., and Davis, K.D., 2003, pp 579 - 589). The second article of this category is Phantom Limbs and Neural Plasticity by Ramachandran and Rogers-Ramachandran published in Archives of Neurology, volume 57, pages 317-320. It has been demonstrated that the region corresponding to the hand in the cortical somatotrophic map, the area 3b, can be activated by stimuli delivered to the ipsilateral face. After amputation of an arm, sensory input from the face begins to activate the hand area of the Penfield homunculus in cortical area S1. The authors tested 18 patients with either arm amputation or brachial avulsion, and they found that 8 patients systemically referred sensation from the face to the phantom limb. In this study, the authors placed a midvertical sagittal mirror on the table in front of the patient. If the patient’s phantom limb was on the left side of the mirror, he was allowed to place his right hand in an exact mirror symmetric location on the right side of the mirror. If the subject looked at the shiny right side of the mirror, the reflection of his own right hand was optically superimposed on the felt location of his phantom limb so that he had a distinct visual illusion that the left amputated limb has been resurrected. If the subject is now made to make mirror-symmetric movements while looking in the mirror, he received visual feedbacks that the phantom limb was obeying his command. The authors conclude that mirror-box therapy is effective since contrary to the popular belief of static brain neuroanatomy, the sensory topography of brain is extremely labile. Even in the adult brain, massive reorganization can occur over extremely short periods, and referred sensations can, therefore, be used as a marker for plasticity in the adult human brain. The authors also propose the implications of effect of mirror-box experiments in the amputees. They suggest that these are clinically useful maneuvers in alleviating abnormal postures and spasms in a phantom limb. This indicates also that in the adult human brain, there is a tremendous amount of back-and-forth interaction between different levels in the hierarchy. It also acknowledges the fact that the mere visual appearance of the moving phantom limb feeds all the way back from the visual to the somatosensory areas of the brain to relieve a spasm in a nonexistent hand. The rehabilitation strategies can be developed by using the fact that body image, despite all its appearance of durability and permanence is actually a purely transitory internal construct (Ramachandran, V.S. and Rogers-Ramachandran, D., 2000, pp. 317-320). The third paper by Ramachandran published in 1993 details the effects of mirror-box therapy. This has been described in the paper, “The perception of phantom limbs” by V.S. Ramachandran and William Hirstein in Brain, volume 121, 1998, pages 1603 to 1630. They have done this experiment on instances where the phantom is extremely painful, and the patients find it difficult to move the arm because even an attempt to generate movements can amplify the pain. This occurred to the authors that if one could somehow enable the patient to generate voluntary movements in his phantom, he might be able to unclench it during the spasms. To achieve this, the authors used the mirror box to convey a visual illusion to the patient that his phantom arm has been resurrected. When the subject looked into the right side of the vertical mirror from above the box, he could see the reflection of his right hand, and this created a vivid visual illusion that his left arm has been resurrected. The authors then asked the subject to simultaneously send motor commands to both hands as if to perform movements in a motor symmetric way (Ramachandran, V.S., 1993, pp. 10413 - 10420). These included clenching and unclenching of the fist and extension and flexion of the wrist. They repeated these procedures several times with identical results. These procedures were tried in a total of 10 patients. They have recorded the results as six patients were felt to be having kinesthetic sensations emerging from the phantom. In four patients, the mirror had no effects on the phantom. Repeated practice led to permanent disappearance of the phantom. Five patients experienced involuntary painful clenching spasms in the phantom hand, and in four of them, the spasms were relieved when the mirror was used to facilitate opening of the phantom hand. It can be argued that this might be a placebo effect, but the authors accept this fact and suggest controlled clinical trials. The authors conclude that taken collectively, there must be a great deal of back-and-forth interaction between vision and touch that may be manipulated in the treatment of phantom limb pain (Ramachandran, V.S. and Hirstein, W., 1998, pp. 1603-1630). The fourth study in this review is “Effects of Regional Anesthesia on Phantom Limb Pain Are Mirrored in Changes in Cortical Reorganization” by Birbaumer, N et al., published in the year 1997 in the Journal of Neuroscience, volume 17(14), pages 5503 to 5508. This paper examined the hypothesis of a functional relationship between cortical reorganization and phantom limb pain. The authors used neuroelectric source imaging to determine changes in cortical reorganization in somatosensory cortex. Three of six phantom limb subjects experienced virtual elimination of current phantom pain attributable to anesthesia that was mirrored by a very rapid elimination of cortical reorganization in somatosensory cortex. This finding suggested that cortical reorganization and phantom limb pain might have a causal relationship. The authors concluded that methods designed to alter cortical reorganization should be examined for their efficacy in the treatment of phantom limb pain (Birbaumer, N. et al., 1997, pp. 5503-5508). The fifth article is “Graded motor imagery for pathologic pain, A randomized controlled trial” by Moseley, published in Neurology in December 2006, volume 67, pages 2139 to 2134. Phantom limb is an example of complex regional pain syndrome after amputations. This is a painful and debilitating condition. This diagnostic term embraces several syndromes including the phenomenon of phantom limb. This is characterized by changes in cortical processing and organization, disturbances in perception, and poor responses to conventional treatment. Mirror visual feedback therapy is effective in intractable pain conditions to impart analgesic effects. Phantom limb pain has many characteristics similar to complex regional pain syndrome, such as, burning, cramping, and mislocalization. Graded motor imagery has been effective in treatment of complex regional pain syndrome; therefore, the author had an objective of studying the effect of graded motor imagery in phantom limb pain. The objective was to investigate whether graded motor imagery would reduce pain and disability for a more general CRPS1 population or for people with phantom limb pain. The author allocated randomly 51 patients with phantom limb pain or CRPS1 to motor imagery. This protocol consisted of 2 weeks each of limb laterality recognition, imagined movements, and mirror movements, or to physical therapy and ongoing medical care. The author observed that there was a main statistical effect of treatment group, but not diagnostic group, on pain and function. The mean with a confidence interval of 95% decrease in pain with a visual analogue scale between pre and post treatment was 23.4 mm for the motor imagery group and 10.5 mm for the control group. Improvement in function was similar, and gains were maintained at 6-month followup. The author concluded that motor imagery reduced pain and disability in these patients with complex regional pain syndrome type 1 or phantom limb pain, but the mechanisms of the effect were unclear (Moseley, G.L., 2006, pp. 2129-2134). Discussion: The findings from these studies have been tabulated and appended at the end of this work. It can be summarized that mirror-box therapy is an important tool in neuro-rehabilitation of the patients who have been amputated and who have pain in the phantom limb. This happens due to cortical reorganization in the sensory cortex due to a dynamic rearrangement of the sensory pathways in the brain following amputation. This hypothesis has been proved by studies that involve neuroelectric imaging of the brain pathways and has also been proved in the clinical practice. Phantom limb pain that has been considerably difficult to treat has been treated successfully by mirror-box therapy in different studies after computation of data and comparing them against data from the control group. However, in some cases, this technique fails, and thus the exact mechanism as to how mirror-box therapy works is unknown, and consequently, further research is mandated in this area to create a standard protocol for mirror-box therapy in phantom limb pain that can be more effectively used in practice. References Birbaumer, N., Flor, H., Lutzenberger, W., and Elbert, T., (1995). The corticalization of chronic pain. In: Pain and the brain: from nociception to cognition. (Bromm B, Desmedt JE, eds), pp 331–344. New York: Raven. Birbaumer, N. et al., (1997). Effects of Regional Anesthesia on Phantom Limb Pain Are Mirrored in Changes in Cortical Reorganization. Journal of Neurosciences; 17: pp. 5503-5508. Hunter, J.P., Katz, J., and Davis, K.D., (2003). The effect of tactile and visual sensory inputs on phantom limb awareness. Brain; 126: pp. 579 - 589. Melzack, R., (1995). Phantom limb pain and the brain. In: Pain and the brain: from nociception to cognition (Bromm B, Desmedt JE, eds), pp. 73–82. New York: Raven. Moseley, G.L., (2006). Graded motor imagery for pathologic pain: A randomized controlled trial. Neurology; 67: pp. 2129 - 2134. Ramachandran, V.S., Stewart, M., and Rogers-Ramachandran, D.C., (1992). Perceptual correlates of massive cortical reorganization. NeuroReport 3: pp. 583–586. Ramachandran, V.S., (1993). Behavioral and Magnetoencephalographic Correlates of Plasticity in the Adult Human Brain. PNAS; 90: pp. 10413 - 10420. Ramachandran, V.S. and Hirstein, W., (1998). The perception of phantom limbs. The D. O. Hebb lecture. Brain; 121: pp. 1603 - 1630. Ramachandran, V.S. and Rogers-Ramachandran, D., (2000). Phantom Limbs and Neural Plasticity. Archives of Neurology; 57: pp. 317-320. Read More