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.
Definition of CRPS
Complex Regional Pain Syndrome has been defined by the International Association for the Study of Pain using the following diagnostic criteria (Boas 1996).
CRPS describes a variety of painful conditions that usually follow injury, occur regionally, have a distal predominance of abnormal findings, which exceed in both magnitude and duration the expected clinical course of the inciting event, often result in significant impairment of motor function and show variable progression over time.
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.