Mirror therapy (MT) or mirror visual feedback (MVF) is a therapy for pain or disability that affects one side of the patient more than the other side. It was invented by Vilayanur S. Ramachandran to treat post-amputation patients who had phantom limb pain (PLP). Ramachandran created a visual (and psychological) illusion of two intact limbs by putting the patient's affected limb into a "mirror box," with a mirror down the center (facing toward a patient's intact limb).
The patient then looks into the mirror on the side with the good limb and makes "mirror symmetric" movements, as a symphony conductor might, or as a person does when they clap their hands. The goal is for the patient to imagine regaining control over a missing limb. Because the subject is seeing the reflected image of the good limb moving, it appears as if the phantom limb is also moving. Through the use of this artificial visual feedback, it becomes possible for the patient to "move" the phantom limb and to unclench it from potentially painful positions.
Mirror therapy has expanded beyond its origin in treating phantom limb pain to the treatment of other kinds of one-sided pain or disability, for instance, hemiparesis in post-stroke patients and limb pain in patients with complex regional pain syndrome.
Based on the observation that phantom limb patients were much more likely to report paralyzed and painful phantoms if the actual limb had been paralyzed prior to amputation (for example, due to a brachial plexus avulsion), Ramachandran and Rogers-Ramachandran proposed the "learned paralysis" hypothesis of painful phantom limbs. [1] Their hypothesis was that every time the patient attempted to move the paralyzed limb, they received sensory feedback (through vision and proprioception) that the limb did not move. This feedback stamped itself into the brain circuitry through a process of Hebbian learning so that, even when the limb was no longer present, the brain had learned that the limb (and subsequent phantom) was paralyzed. [2]
Ramachandran created the mirror box to relieve pain by helping an amputee imagine motor control over a missing limb. Mirror therapy is now also widely used for treatment of motor disorders such as hemiplegia or cerebral palsy. As Deconick et al. state in a 2014 review, the mechanism of improved motor control and pain relief may differ from the mechanism of pain relief. Deconick et al., who reviewed only the effects of MVF on sensorimotor control, found that MVF can exert a strong influence on the motor network, mainly through increased cognitive penetration in action control. [3]
Although there has been much research on MVF, authors of many review articles complain about the poor methodology often used, for example, small sample sizes or lack of control groups. For this reason, one 2016 review (based on a review of 8 studies) concluded that the level of evidence was insufficient to recommend MT as a first intention treatment for phantom limb pain. [4]
A 2018 review, (based on 15 studies conducted between 2012 and 2017, out of a pool of 115 publications) also criticized the quality of many reports on mirror therapy (MT), but concluded that "MT seems to be effective in relieving PLP, reducing the intensity and duration of daily pain episodes. It is a valid, simple, and inexpensive treatment for PLP." [5]
A 2018 literature review of phantom limb pain stated that, in randomized controlled trials, mirror therapy reduced pain. [6]
Treatment with mirror therapy soon expanded beyond its origin in treating phantom limb pain to treatment of other kinds of one-sided pain and loss of motor control, for example in stroke patients with hemiparesis. In 1999 Ramachandran and Eric Altschuler expanded the mirror technique from amputees to improving the muscle control of stroke patients with weakened limbs. [7]
A review article published in 2016 concluded that "Mirror therapy (MT) is a valuable method for enhancing motor recovery in poststroke hemiparesis." [8]
According to a 2017 review of fifteen studies that compared mirror therapy to conventional rehabilitation for the recovery of upper-limb function in stroke survivors, mirror therapy was more successful than CR in promoting recovery. [9]
A 2018 review based on 1685 patients recovering from hemiplegic stroke found mirror therapy provided significant pain relief, while improving motor functions and activities of daily living (ADL). [10]
Thirteen out of seventeen randomized controlled trials found that MT was beneficial for post-stroke patients' legs and feet, according to a 2019 review paper. [11]
Despite considerable research, as of 2016 the underlying neural mechanisms of mirror therapy (MT) for stroke were still unclear. [8] [12] As Deconick et al. state in a 2014 review, the mechanism of improved motor control may differ from the mechanism of pain relief. [3]
Mirror therapy is also a recommended therapy for complex regional pain syndrome (CRPS). [13] [14]
Since the 2000s, the visual illusion of regaining control of a damaged limb, which mirror therapy provides, has also been available through virtual reality or robotics. [15]
Expressive aphasia is a type of aphasia characterized by partial loss of the ability to produce language, although comprehension generally remains intact. A person with expressive aphasia will exhibit effortful speech. Speech generally includes important content words but leaves out function words that have more grammatical significance than physical meaning, such as prepositions and articles. This is known as "telegraphic speech". The person's intended message may still be understood, but their sentence will not be grammatically correct. In very severe forms of expressive aphasia, a person may only speak using single word utterances. Typically, comprehension is mildly to moderately impaired in expressive aphasia due to difficulty understanding complex grammar.
Hemiparesis, also called unilateral paresis, is the weakness of one entire side of the body. Hemiplegia, in its most severe form, is the complete paralysis of one entire side of the body. Either hemiparesis or hemiplegia can result from a variety of medical causes, including congenital conditions, trauma, tumors, traumatic brain injury and stroke.
Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage."
Complex regional pain syndrome (CRPS Type 1 and Type 2), sometimes referred to by the hyponyms Reflex Sympathetic Dystrophy (RSD) or Reflex Neurovascular Dystrophy (RND), is a rare and severe form of neuroinflammatory and dysautonomic disorder causing chronic pain, neurovascular, and neuropathic symptoms. Although it can vary widely, the classic presentation occurs when severe pain from a physical trauma or neurotropic viral infection outlasts the expected recovery time, and may subsequently spread to uninjured areas. The symptoms of types 1 and 2 are the same except type 2 is associated with nerve injury.
A phantom limb is the sensation that an amputated or missing limb is still attached. It is a chronic condition which is often resistant to treatment. When the cut ends of sensory fibres are stimulated during thigh movements, the patient feels as if the sensation is arising from the non-existent limb. Sometimes the patient might feel pain in the non-existent limb. Approximately 80–100% of individuals with an amputation experience sensations in their amputated limb. However, only a small percentage will experience painful phantom limb sensation. These sensations are relatively common in amputees and usually resolve within two to three years without treatment. Research continues to explore the underlying mechanisms of phantom limb pain (PLP) and effective treatment options.
Vilayanur Subramanian Ramachandran is an Indian-American neuroscientist. He is known for his wide-ranging experiments and theories in behavioral neurology, including the invention of the mirror box. Ramachandran is a distinguished professor in UCSD's Department of Psychology, where he is the director of the Center for Brain and Cognition.
Anosognosia is a condition in which a person with a disability is cognitively unaware of having it due to an underlying physical condition. Anosognosia results from physiological damage to brain structures, typically to the parietal lobe or a diffuse lesion on the fronto-temporal-parietal area in the right hemisphere, and is thus a neuropsychiatric disorder. A deficit of self-awareness, the term was first coined by the neurologist Joseph Babinski in 1914, in order to describe the unawareness of hemiplegia.
The primary goals of stroke management are to reduce brain injury and promote maximum patient recovery. Rapid detection and appropriate emergency medical care are essential for optimizing health outcomes. When available, patients are admitted to an acute stroke unit for treatment. These units specialize in providing medical and surgical care aimed at stabilizing the patient's medical status. Standardized assessments are also performed to aid in the development of an appropriate care plan. Current research suggests that stroke units may be effective in reducing in-hospital fatality rates and the length of hospital stays.
The Bobath concept is an approach to neurological rehabilitation that is applied in patient assessment and treatment. The goal of applying the Bobath concept is to promote motor learning for efficient motor control in various environments, thereby improving participation and function. This is done through specific patient handling skills to guide patients through the initiation and completing of intended tasks. This approach to neurological rehabilitation is multidisciplinary, primarily involving physiotherapists, occupational therapists, and speech and language therapists. In the United States, the Bobath concept is also known as 'neuro-developmental treatment' (NDT).
Phantom pain is a painful perception that an individual experiences relating to a limb or an organ that is not physically part of the body, either because it was removed or was never there in the first place.
Neuroplasticity, also known as neural plasticity or brain plasticity, is the ability of neural networks in the brain to change through growth and reorganization. It is when the brain is rewired to function in some way that differs from how it previously functioned. These changes range from individual neuron pathways making new connections, to systematic adjustments like cortical remapping or neural oscillation. Other forms of neuroplasticity include homologous area adaptation, cross modal reassignment, map expansion, and compensatory masquerade. Examples of neuroplasticity include circuit and network changes that result from learning a new ability, information acquisition, environmental influences, pregnancy, caloric intake, practice/training, and psychological stress.
Monoplegia is paralysis of a single limb, usually an arm. Common symptoms associated with monoplegic patients are weakness, numbness, and pain in the affected limb. Monoplegia is a type of paralysis that falls under hemiplegia. While hemiplegia is paralysis of half of the body, monoplegia is localized to a single limb or to a specific region of the body. Monoplegia of the upper limb is sometimes referred to as brachial monoplegia, and that of the lower limb is called crural monoplegia. Monoplegia in the lower extremities is not as common of an occurrence as in the upper extremities. Monoparesis is a similar, but less severe, condition because one limb is very weak, not paralyzed. For more information, see paresis.
Phantom eye syndrome (PES) is a phantom pain in the eye and visual hallucinations after the removal of an eye.
Extended physiological proprioception (EPP) is a concept pioneered by D.C. Simpson (1972) to describe the ability to perceive at the tip of a tool. Proprioception is the concept is that proprioceptors in the muscles and joints, couple with cutaneous receptors to identify and manage contacts between the body and the world. Extended physiological proprioception allows for this same process to apply to contacts between a tool that is being held and the world. The work was based on prostheses developed at the time in response to disabilities incurred by infants as the result of use of the drug thalidomide by mothers from 1957 to 1962, with the tool in this case simply being the prosthesis itself. How a person identifies with themself changes after a lower limb amputation affects body image, functioning, awareness, and future projections.
Constraint-induced movement therapy is a form of rehabilitation therapy that improves upper extremity function in stroke and other central nervous system damage patients by increasing the use of their affected upper limb. Due to its high duration of treatment, the therapy has been found to frequently be infeasible when attempts have been made to apply it to clinical situations, and both patients and treating clinicians have reported poor compliance and concerns with patient safety. In the United States, the high duration of the therapy has also made the therapy not able to get reimbursed in most clinical environments.
Body schema is an organism's internal model of its own body, including the position of its limbs. The neurologist Sir Henry Head originally defined it as a postural model of the body that actively organizes and modifies 'the impressions produced by incoming sensory impulses in such a way that the final sensation of body position, or of locality, rises into consciousness charged with a relation to something that has happened before'. As a postural model that keeps track of limb position, it plays an important role in control of action.
Sensory stimulation therapy (SST) is an experimental therapy that aims to use neural plasticity mechanisms to aid in the recovery of somatosensory function after stroke or cognitive ageing. Stroke and cognitive ageing are well known sources of cognitive loss, the former by neuronal death, the latter by weakening of neural connections. SST stimulates a specific sense at a specific frequency. Research suggests that this technique may reverse cognitive ageing by up to 30 years, and may selectively improve or impair two point discrimination thresholds.
Cortical remapping, also referred to as cortical reorganization, is the process by which an existing cortical map is affected by a stimulus resulting in the creating of a 'new' cortical map. Every part of the body is connected to a corresponding area in the brain which creates a cortical map. When something happens to disrupt the cortical maps such as an amputation or a change in neuronal characteristics, the map is no longer relevant. The part of the brain that is in charge of the amputated limb or neuronal change will be dominated by adjacent cortical regions that are still receiving input, thus creating a remapped area. Remapping can occur in the sensory or motor system. The mechanism for each system may be quite different. Cortical remapping in the somatosensory system happens when there has been a decrease in sensory input to the brain due to deafferentation or amputation, as well as a sensory input increase to an area of the brain. Motor system remapping receives more limited feedback that can be difficult to interpret.
Tactile hallucination is the false perception of tactile sensory input that creates a hallucinatory sensation of physical contact with an imaginary object. It is caused by the faulty integration of the tactile sensory neural signals generated in the spinal cord and the thalamus and sent to the primary somatosensory cortex (SI) and secondary somatosensory cortex (SII). Tactile hallucinations are recurrent symptoms of neurological diseases such as schizophrenia, Parkinson's disease, Ekbom's syndrome and delirium tremens. Patients who experience phantom limb pains also experience a type of tactile hallucination. Tactile hallucinations are also caused by drugs such as cocaine and alcohol.
Limb telescoping is the progressive shortening of a phantom limb as the cortical regions are reorganized following an amputation. During this reorganization, proximal portions of the residual limb are perceived as more distal parts of the phantom limb. Such effect is responsible for increased phantom pain due to the discrepancy between the patient’s body perception and their actual body. This effect may last from weeks up to years after post-amputation.
As to the effect of MT on PLM, the 8 studies concerned reported effectiveness of MT: 4 with a low level of evidence and 4 with a high level of evidence...We cannot recommend MT as a first intention treatment in PLP. The level of evidence is insufficient.
It is a valid, simple, and inexpensive treatment for PLP. The methodological quality of most publications in this field is very limited, highlighting the need for additional, high-quality studies to develop clinical protocols that could maximise the benefits of MT for patients with PLP.
One of the studies showed all 22 patients went through mirror therapy reported a decrease in pain after 4 weeks of treatment. In contrast, only 17% and 33% of the patients in the two controlled groups reported decrease in pain.
Use of the mirror may also help recruit the premotor cortex to help with motor rehabilitation...On a number of neurological and psychological levels, mirror therapy may help to reverse elements of learned disuse of the affected limb.
Fifteen studies were included in the systematic review. Recovery of the upper limb, upper limb function and gross manual dexterity were frequently measured in these studies...In the primary variables in promoting recovery, MT alone showed better results in acute and chronic stroke patients in upper limb functioning than either conventional rehabilitation (CR ) or CR plus MT.
Thirty-seven RCTs (42 analyses, 1685 subjects) were eligible for inclusion in the meta-analysis... Overall, MT could effectively improve motor function and ADL, as well as relieve pain for stroke survivors.
Seventeen RCTs involving 633 participants were included. Thirteen studies reported a significant between-group difference favoring mirror therapy in at least one lower extremity outcome.
The main treatment strategy for CRPS is physical rehabilitation for return of function and mirror therapy is one of many possible strategies to aid in this goal...There appears to be a clear indication for the use of mirror therapy to be included in the multidisciplinary treatment of CRPS types 1 and 2 with a positive effect on both pain and motor function.
Mirror therapy (MT) and graded motor imagery programmes (GMIP) are two specific modalities of physical therapy which are especially promising options for managing CRPS.