Brain alterations and neurocognitive dysfunction in patients with complex regional pain syndrome

Few studies have examined the involvement of specific subregions of the prefrontal cortex in complex regional pain syndrome (CRPS). We analyzed cortical thickness to identify morphologic differences in local brain structures between patients with CRPS and healthy control subjects (HCs). Furthermore, we evaluated the correlation between cortical thickness and neurocognitive function. Cortical thickness was measured in 25 patients with CRPS and 25 HCs using the FreeSurfer method. Pain severity and psychiatric symptoms were assessed using the Short Form McGill Pain Questionnaire and the Beck Depression and Anxiety Inventories, respectively. Neurocognitive function was assessed via the Wisconsin Card Sorting Test and the stop-signal task. The right dorsolateral prefrontal cortex and left ventromedial prefrontal cortex were significantly thinner in CRPS patients than in HCs. CRPS patients made more perseveration errors on the Wisconsin Card Sorting Test and had longer stop-signal task reaction times than HCs. Although the Beck Depression Inventory and the Beck Anxiety Inventory differ significantly between the groups, they were not correlated with cortical thickness. Our study suggests that the pathophysiology of CRPS may be related to reduced cortical thickness in the dorsolateral prefrontal cortex and the ventromedial prefrontal cortex. The structural alterations in dorsolateral prefrontal cortex may explain executive dysfunction and disinhibited pain perception in CRPS.

Perspective: The present study reports decreased cortical thickness in the prefrontal cortex and neurocognitive dysfunctions in patients with CRPS. These findings may contribute to the understanding of pain-related impairments in cognitive function and could help explain the symptoms or progression of CRPS.