Neuropsychological deficits associated with Complex Regional Pain Syndrome.

We sought to elucidate the existence of neuropsychological subtypes in Complex Regional Pain Syndrome (CRPS). One hundred thirty seven patients with CRPS were administered tests that assess executive control, naming/lexical retrieval, and declarative memory. A 2-step cluster analysis that does not require any a priori specification regarding the number of clusters, classified patients into three groups. Group 1 obtained scores that were in the average range on all tests (n = 48; normal CRSP group). Group 2 (n = 58; dysexecutive CRSP group) presented with mild impairment or statistically low average test performance on working memory/verbal fluency tests. Group 3 (n = 31; global CRSP group) produced scores in the statistically low average/borderline range on all tests with particularly reduced scores on naming/declarative memory tests. Between-group analyses found that the CRPS group 1 obtained higher scores than CRPS groups 2 and 3 on all tests. However, groups 2 and 3 were equally impaired on executive tests. CRPS group 3 was impaired on tests of naming/memory tests compared to the other groups. Significant neuropsychological deficits are present in 65% of patients, with many patients presenting with elements of a dysexecutive syndrome and some patients presenting with global cognitive impairment.