Mirror box therapy was first described by V.S. Ramachandran for the relief of Phantom Limb Pain, but has since been proven in the treatment of Stroke Rehabilitation, and Complex Regional Pain Syndrome (CRPS) / RSD, as well as for Hand and Foot Rehabilitation following an injury or surgery.
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Stroke arises from an acute interruption of blood (oxygen and glucose) supply to the brain tissue. A new and possibly more descriptive term for stroke which has a similar meaning and emphasis as heart attack is “brain attack”, indeed some hospitals are now organising “brain attack teams” to manage the immediate stroke episode in a similar fashion to the more familiar cardiac arrest and trauma teams.
By the nature of the injury and dependant upon the area of damage within the brain, stroke can cause a variety of loss in the motor pathways that control movement.
Within the last few years functional magnetic resonance imaging alongside non-invasive methods of cortical stimulation have begun to reveal the importance of the functional integration of the motor and somatosensory cortex in limb movement.
The evidence for bilateral movement training especially in upper limb rehabilitation is beginning to build. It has been suggested that visualising and undertaking symmetrical bilateral movements post stroke enhance neuroplastic changes within the brain. The theories suggest increased disinhibition of the motor cortex allowing increased use of spared pathways within the damaged hemisphere, increased activity of motor command pathways in the affected hemisphere running to the spinal nerves and increased activation of the pathways from the unaffected hemisphere to supplement the damaged crossed corticospinal pathways.
The role of mirror box / visual therapy in this bilateral movement training is central to its success.
Phantom Limb Pain
Phantom sensations are said to be present in in all amputees and in children born with missing limbs. It is thought that since the sensations are present in children born with missing limbs the human brain is “hard wired” in the somatosensory cortex (the strip of brain that runs between the ears) to expect sensation from all 4 limbs.
Phantom limb pain occurs in up to 80% amputees and unfortunately tends to be therapy resistant and chronic. Indeed the limb does not need to be lost, phantom pains may occur after a disconnect injury such as a spinal cord injury or brachial plexus avulsion which are common after motorbike accidents. Phantom pain is typically described as burning aching or as if the limb, foot, hand is being crushed or held in a vice like grip
Historically the causes of phantom pain have focused on the stump. Pain has often been ascribed to local nerve stump irritation, however as our knowledge of the nervous system improved the proposed causes of phantom pain have migrated centrally, initially to integration of information in the spinal cord, and then to the central processing of information in the higher centres of the brain especially the somatosensory and motor cortex.
It has recently been postulated that Phantom limb pain is a manifestation of a need like state of the mind to “feel and see” the limb move. This hypothesis is backed by the work that demonstrated reduced pain after use of an electric prosthetic limb, which showed normalisation of the somatosensory cortex in the pain relieved state. It is also validated by the use of mirror box therapy in the management of phantom pain states. This concept of phantom pain arising out of an imbalance between the sensory evaluation of incoming information from the missing limb and the motor co-ordination of the limb is now central to both the efficacy of mirror therapy and the modern concept of phantom pain as a central (brain) problem rather than a stump or peripheral problem.
1. The main stays of treatment for phantom pain revolve around the use of standard neuropathic medications. For example drugs, such as anticonvulsants, tri cyclic antidepressants and opioids.
2. Topical therapies to reduce stump irritability are also advocated, capsaicin cream, steroid injections and lidoderm patches.
3. Stimulation therapy, TENS, Spinal cord stimulation.
4. Mirror therapy and visualisation techniques.
Complex Regional Pain Syndrome
Complex Regional Pain Syndrome (CRPS) is a chronic pain condition, which has been recognised since it was first described by an American neurologist Dr Mitchel in injured soldiers during the American Civil War. Dr Mitchel astutely suggested that the condition was due to irritation or damage of nerves that he could not see. He described the condition as “Causalgia” a word derived from “kausticos” Greek for “able to burn”. Since its first description CRPS as it is now known, has been described as Sudeks Atrophy, Reflex Sympathetic Dystrophy (RSD), Shoulder-Hand syndrome, Algodystrophy, Neuroalgodystrophy, Reflex Neurovascular Dystrophy and Sympathetically Maintained Pain.
CRPS Type I (formerly known as RSD)
- Follows an initiating noxious event.
- Spontaneous pain and/ or allodynia and hyperalgaesia occur beyond the territory of single peripheral nerve(s), and is disproportionate to the inciting event.
- There is or has been evidence of oedema, skin blood flow abnormality, or abnormal sudomotor activity, in the region of the pain since the inciting event.
- The diagnosis is excluded by the existence of conditions that would otherwise account for the degree of pain or dysfunction.
CRPS Type II (formerly known as Causalgia)
This syndrome follows nerve injury. It is similar in all other respects to CRPS Type I.
1. Is a more regionally confined presentation about a joint or area, associated with a noxious event.
2. Spontaneous pain and/ or allodynia and hyperalgaesia are usually limited to the area involved but may spread variably distal or proximal to the area, not in the territory of a dermatomal or peripheral nerve distribution.
3. Intermittent and variable oedema, skin blood flow change, temperature change, abnormal sudomotor activity, and motor dysfunction, disproportionate to the inciting event are present in the area involved.
Patients with CRPS typically complain of a very painful extremity which may not of suffered a significant injury, the limb is described as, hot or cold, burning sweating, flushing alternatively hot and cold, itching, very sensitive to touch, weak, incredibly painful to move and unbearable. The pain is invariably unresponsive to over the counter medications and simple analgaesics. Patients may be suicidal.
What causes CRPS?
The truth is we do not yet know the answer to this question.
The current thinking suggests that CRPS is a result of dysfunction of both the peripheral and central nervous systems. Associated with this dysfunction is often a maladaption and malfunction of the autonomic nervous system to these changes. Recent fMRI work has also suggested that within the higher centres (brain), the integration of the motor pathways to the limb along with somatosensory cortex integration play an important role in the pathophysiology of the process. In other words the bits of your brain that integrate movement control of the limb and sensory appreciation of the limb go awry. It is precisely at this point that mirror visualisation techniques or mirror box therapy works.
There is unfortunately no single therapy that has been shown in clinical trials to be of overwhelming superiority in the management of CRPS.
Treatment goals are to improve pain relief alongside allowing gradual mobilisation of the affected limb in a paced and goal oriented way. There is a consensus view now that in the long term gradually exercising and using the limb achieve best results. Views differ on quite how tough the therapist needs to be to achieve this.
In order to achieve the above patients may be trialled on any or all of the following.
- Neuropathic medications such as anticonvulsants, tricyclic antidepressants and opioids analgaesics.
- Topical Therapies such as DMSO cream and capsaicin.
- Sympathetic Blocks
- Stimulation therapies such as TENS or Spinal Cord Stimulation.
- Physiotherapy and Occupational Therapy
There is growing evidence from both clinical trial work, anecdotal case reports and fMRI work that mirror box therapy and visualisation techniques have a significant effect on assisting in the rehabilitation of the limb.