Plasticity of complex regional pain syndrome (CRPS) in children.

Complex regional pain syndrome I (CRPS I) is defined by the International Association for the Study of Pain (IASP) criteria to include pain that is disproportionate to the inciting event, sensory disturbances such as allodynia/ hyperalgesia, autonomic dysfunction, and motor dysfunction that usually occurs after trauma that is frequently trivial and generally expressed in an extremity. These symptoms are well described in the adult population, but there are relatively few data or reports of its prevalence in the pediatric population. Recent studies have demonstrated that unlike the adult population, about 90% of the cases reported are females in a range of 8 to 16 years, the youngest being 3 years old. There tends to be delay in recognizing the diagnosis, which may be as long as 4 months. In contrast to adults, the response to treatment, particularly exercise therapy with behavioral management will achieve almost 97% remission. While the pathophysiology is poorly understood, many features, particularly the neurologic abnormalities, suggest both peripheral and central nervous system involvement. Peripheral small fiber neuropathy as an etiology and inflammation involving small nerve fibers (neurogenic inflammatory pain) has been suggested. A tissue inflammatory etiology has been investigated over the past 25 years. However, these inflammatory aspects differ from those seen in other conditions involving tissue inflammation. The suggestion that CRPS in children is a different clinical entity than that seen in the adult, is probably incorrect, as recent evidence would suggest that the pathophysiology is most likely identical involving endocrine, behavioral, developmental, and environmental factors that distinguish clinical presentation in children from the adult. Behavioral management is a mandatory accompaniment of any program of exercise therapy and the sometimes extreme sensory disturbances and parental enmeshment do distinguish the clinical presentation from that in the adult. Interventional procedures may be required in the face of extreme allodynia preventing exercise therapy, and in occasional cases interruption of the sympathetic nerves may reverse this symptom in a few children. Occasionally, continuous analgesia techniques such as that which can be delivered by tunneled epidural catheter or an externalized neurostimulator (spinal cord stimulation) for short periods of time are effective.