Clinical Phenotypes and the Effects of Interdisciplinary Pain Treatment in Pediatric Complex Regional Pain Syndrome.

BACKGROUND

This investigation aimed to replicate phenotypes in pediatric complex regional pain syndrome (CRPS) previously identified in adult CRPS patients. The impact of an intensive pain therapeutic approach in pediatric CRPS was also evaluated.

METHODS

Neurological examination data were obtained from two samples of children with CRPS (cohort #1; N = 24 and cohort #2; N = 14). The structure among CRPS signs was analyzed on pooled data from cohorts #1 and 2 using hierarchical clustering. A phenotype score was quantified for patients and then submitted to unsupervised k-means clustering. Patients in cohort #2 were enrolled in a 4-6-week treatment program consisting of psychological, physical, and occupational therapy. Questionnaires about pain and mental and physical health were evaluated at treatment admission and discharge.

RESULTS

A two-cluster structure of CRPS signs could be replicated in the pediatric population. Cluster #1 includes skin color, temperature, and edema resembling peripheral inflammation ("peripheral" phenotype). Cluster #2 grouped together motor disorders, minor injury, glove/stocking-like sensory deficits, and allodynia ("central" phenotype). K-means clustering also showed three phenotypes, "peripheral" (N = 12), "central" (N = 10), and "mixed" (N = 17), similar to adults. The impact of treatment was revealed for pain affect, pain behavior, psychological distress, depression, pain catastrophizing levels, as well as physical activity and strength (Cohen's d = [0.8-1.3]).

CONCLUSIONS

CRPS phenotypes reflecting major pathophysiological mechanisms of peripheral inflammation and central reorganization are identifiable in adult and pediatric patients, suggesting phenomenological features of the disease. An intensive interdisciplinary pain treatment approach was effective in reducing CRPS severity and restoring function in pediatric CRPS.