Neuropsychological Changes in Complex Regional Pain Syndrome (CRPS)
Table 2
Summary of neuropsychological functions investigated in people with CRPS in research studies published between July 1995 and June 2019.
Neuropsychological function/symptom
Measure/task
Performance of participants with CRPSa,b
Study detailsc
Body representation
Self-reported body perception
Interview
Distorted representation of the affected limb (altered perceptions of size, shape, and weight; desire to amputate; mismatch between sensations and appearance of the limb; erasure of its anatomical parts; poor awareness of its position; and asomatognosia)
Motor neglect for the affected limb (slower initiation, execution, and decreased amplitude and spatial extent of movements, required directed attention to move the affected limb, and occurrence of involuntary movements)
Bias away from the affected limb (when tactile stimuli delivered to uncrossed hands) and from the affected side of space (when tactile stimuli delivered to hands crossed over body midline), relative to the unaffected limb and side of space
Bias away from the affected relative to unaffected side of space and limb (when visual stimuli presented in near space without hands, or on the surface of uncrossed hands, but not when hands were crossed over body midline)
Slower and more variable movements (with the affected vs. unaffected hand in both sides of space, and with both hands in the affected vs. unaffected side of space)
Identification of indicated fingers (verbally, by touch, pointing, or movement)
Finger agnosia on the affected limb (48-59%); longer reaction times, reduced accuracy, and increased variability of finger discrimination (on both hands, but worse on the affected hand)
Cohen et al. [71], , HC, BL; Förderreuther et al. [37], , BL; Kuttikat et al. [77], , HC, BL
Knowledge about order and orientation of numbers and letters/words
Spontaneous and dictated writing and copying
Mirror reversal in writing and reading, horizontal inversion of letters and words, and letters and numbers ordering in writing (cases for the affected hand, both hands, and unaffected hand)
Cohen et al. [71], , HC, BL; Robinson et al. [65], , UL
Letter orientation recognition
Normal (for standard vs. reflected letters and left vs. right side of space)
Digit span, Boston naming test, animal (semantic) fluency, letter fluency, and California verbal learning test II
Global processing impairment (particularly impaired naming, declarative memory, and executive function; 23%) or mild dysexecutive syndrome (particularly impaired working memory and verbal fluency; 42%)
aPercentages represent the proportion of individuals with CRPS out of the total CRPS sample who presented with abnormal performance. We reported percentages where available; in other cases, we presented group effects. bNormal performance indicates that there were no differences between participants with CRPS and control participants and/or between the affected and unaffected side among participants with CRPS. c represents CRPS sample size. Where applicable, we specified which control group was included (HC = healthy/pain-free controls; PC = pain controls; NC = normative data or comparison against zero; † = no significant difference between CRPS and control group) and which limb(s) were tested (AL = affected limb; UL = unaffected limb; BL = both limbs).