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 | |||
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| 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) | Galer et al. [33], N = 11; Lewis et al. [34], N = 27 |
| Neglect-like symptoms questionnaire [35, 36] | Asomatognosia (feelings of foreignness and lack of ownership of the affected limb) (17-90%) | Förderreuther et al. [37], N = 40; Frettlöh et al. [35], N = 123, PC; Galer and Jensen [36], N = 224; Kolb et al. [38], N = 20, HC, PC†; Michal et al. [39], N = 50, PC; Reinersmann et al. [40], N = 24, PC†, [41], N = 24, PC; Wittayer et al. [42], N = 53 | |
| Bath CRPS body perception disturbance scale [43] | Distorted representation of the affected limb (see above) | Brun et al. [44], N = 13; Bultitude et al. [45], N = 24; Kotiuk et al. [46], N = 50; Lewis and Schweinhardt [47], N = 22, HC; Tajadura-Jiménez et al. [48], N = 12 | |
| Objective limb size | Estimation of actual limb size based on enlarged or shrunk images | Overestimation of size of the affected limb | Moseley [49], N = 50, PC, AL; Peltz et al. [50], N = 30, HC, AL |
| Tactile distance judgements following tool use | Perceived lengthening of the unaffected arm and shortening of the affected arm | Vittersø et al. [51], N = 36, HC, BL | |
| Limb position sense | Limb position matching | Reduced accuracy in both limbs | Brun et al. [44], N = 13, HC, BL; Lewis et al. [52], N = 20, HC, BL |
| Manual straight-ahead pointing (eyes closed) | Bias towards the affected side of space | Christophe et al. [53], N = 1, NC, BL; Jacquin-Courtois et al. [54], N = 1, NC, HC, AL | |
| Normal | Christophe et al. [55], N = 7, NC, BL; Kolb et al. [38], N = 20, HC, PC, BL | ||
| Limb movement sense | Estimation of the extent of actual movement relative to altered visual feedback | Reduced accuracy and precision in the affected limb | Brun et al. [44], N = 13, HC, AL |
| Mental limb rotation/internal representation of limbs | Limb laterality recognition test | Reduced accuracy for the affected vs. unaffected limb images | Johnson et al. [56], N = 29 |
| Longer reaction times for the affected vs. unaffected limb images | Johnson et al. [56], N = 29; Moseley [57], N = 18, HC; Reid et al. [58], N = 130; Schwoebel et al. [59], N = 13, HC, [60], N = 12 | ||
| Longer reaction times for images of both limbs in the affected vs. unaffected side of space | Reid et al. [58], N = 130 | ||
| Longer reaction times for images of both limbs | Bultitude et al. [45], N = 24, HC; Kohler et al. [61], N = 15, HC; Reinersmann et al. [62], N = 12, HC, PC†; Wittayer et al. [42], N = 53, HC | ||
| Normal | Breimhorst et al. [63], N = 20, HC; Reinersmann et al. [40], N = 24, HC, PC | ||
| Multisensory integration/body ownership | Rubber hand illusion | Normal | Reinersmann et al. [41], N = 24, HC, PC, BL |
| Bimanual representation of limbs | Artificial finger illusion | Reduced illusion strength for vision-proprioception only (abnormal bimanual representation); normal with tactile input | Wang et al. [64]; N = 20, HC, BL |
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| Lateralised spatial cognition | |||
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| Self-reported motor neglect | Interview/clinical observation | 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) | Galer et al. [33], N = 11 |
| Neglect-like symptoms questionnaire [35, 36] | Motor neglect for the affected limb (see above) (17-90%) | Frettlöh et al. [35], N = 123, PC; Galer and Jensen [36], N = 224; Kolb et al. [38], N = 20, HC, PC†; Michal et al. [39], N = 50, PC; Reinersmann et al. [40], N = 24, PC†, [41], N = 42, PC; Wittayer et al. [42], N = 53 | |
| Visuomotor spatial attention | Line bisection | Bias towards the affected relative to unaffected side of space | Christophe et al. [53], N = 1, NC, BL; Jacquin-Courtois et al. [54], N = 1, HC, NC, AL; Förderreuther et al. [37], N = 29, HC, BL |
| Bias away from the affected relative to unaffected side of space | Robinson et al. [65], N = 1, NC | ||
| Normal | Christophe et al. [55], N = 7, NC, BL; Förderreuther et al. [37], N = 29, HC, BL; Kolb et al. [38], N = 20, HC, PC; Reid et al. [58], N = 13, NC, BL; Reinersmann et al. [40], N = 24, HC, PC | ||
| Robot-assisted line bisection | Bias towards the left relative to right side of space | Verfaille et al. [66], N = 15, HC, UL | |
| Line bisection on the limbs | Bias away from the affected relative to unaffected side of space (on the affected limb and on both limbs on the affected side of space) | Reid et al. [58], N = 13, NC, BL | |
| Clock drawing test | Normal | Kolb et al. [38], N = 20, HC, PC | |
| Egocentric frame of reference | Visual subjective body midline | Bias towards the affected relative to unaffected side of space (only in the dark) | Christophe et al. [53], N = 1, NC; Jacquin-Courtois et al. [54], N = 1, HC, NC; Sumitani et al. [67], N = 27, HC [68], N = 36, HC, [69], N = 5, NC; Uematsu et al. [70], N = 22, PC |
| Bias towards the left relative to right side of space (in the dark) | Reinersmann et al. [40], N = 24, HC, PC | ||
| Normal (in the dark) | Christophe et al. [55], N = 7, NC; Wittayer et al. [42], N = 53, HC | ||
| Tactile spatial attention | Confrontation test (detection of concurrent stimulation on both limbs) | Omissions of stimuli on the affected side of the body (extinction; 14%) | Cohen et al. [71], N = 22, BL |
| Temporal order judgements | Bias away from the affected relative to unaffected limb (when tactile stimuli delivered to uncrossed hands) | Reid et al. [58], N = 13, NC | |
| Temporal order judgements | 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 | Moseley et al. [72], N = 10, [73], N = 10, HC | |
| Normal (crossed and uncrossed hands) | Filbrich et al. [74], N = 12, NC | ||
| Auditory spatial attention | Temporal order judgements | Normal | Reid et al. [58], N = 13, NC |
| Visual spatial attention | Temporal order judgements | 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) | Bultitude et al. [45], N = 24, HC |
| Bias away from the affected relative to unaffected side of space (when visual stimuli presented near uncrossed hands but not far from the hands) | Filbrich et al. [74], N = 14, NC | ||
| Orienting saccades to cued and noncued stimuli in the left and right visual fields | Normal | Filippopulos et al. [75], N = 8, HC | |
| Speeded detection task | Longer reaction times in the right side of space | Kolb et al. [38], N = 20, HC, PC | |
| Internal representation of space | Mental number line bisection | Deviation away from the affected relative to unaffected side of space | Sumitani et al. [67], N = 27, HC |
| Deviation towards the affected relative to unaffected side of space | Christophe et al. [53], N = 1, NC; Jacquin-Courtois et al. [54], N = 1, NC, HC | ||
| Spatially-defined motor control | Rhythmic finger tapping | Normal/no hands asymmetry (with one and both hands, in uncrossed and crossed posture, with and without visual feedback) | Christophe et al. [55], N = 7, HC, BL |
| Normal/no hands asymmetry (with one and both hands, hands close together or further apart, without visual feedback) | Christophe et al. [53], N = 1, BL | ||
| Speeded button pressing | 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) | Reid et al. [76], N = 13, BL | |
| Circle drawing task | Reduced accuracy (with the affected vs. unaffected hand in both sides of space, and with both hands in the affected vs. unaffected side of space) | Reid et al. [76], N = 13, BL | |
| Normal/no hands asymmetry | Christophe et al. [55], N = 7, HC, BL | ||
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| Non-spatially-lateralised cognition | |||
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| Object recognition | Tactile recognition of objects | Astereognosia for the affected hand (64%) | Cohen et al. [71], N=22, HC, BL |
| Visual recognition of objects | Normal | Robinson et al. [65], N = 1, NC | |
| Face recognition | Benton test of face perception | Prosopagnosia | Robinson et al. [65], N = 1, NC |
| Finger identification | 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], N = 22, HC, BL; Förderreuther et al. [37], N = 73, BL; Kuttikat et al. [77], N = 13, HC, BL |
| Normal | Robinson et al. [65], N = 1, NC, UL | ||
| Tactile recognition of writing on the skin | Identification of letters and numbers traced onto one's palm | Dysgraphaesthesia on the affected hand (36%) | Cohen et al. [71], N = 22, HC, BL |
| Constructional ability | Copying or constructing named geometric figures using drawing or matchsticks | Constructional apraxia for the affected hand (32%) | Cohen et al. [71], N = 22, HC, BL |
| Kohs block test | Normal | Kolb et al. [38], N = 20, HC, PC | |
| Numerical and language processing | Counting, mental arithmetic, reading, repeating, writing, copying, identifying numbers and letters/words, spelling | Dyscalculia (27%); dysgraphia for the affected hand (27%) | Cohen et al. [71], N = 22, HC, BL |
| Speech repetition | Repetition of words and sentences, confrontation naming | Conductional dysphasia (4%) | Cohen et al. [71], N = 22, HC |
| Verbal fluency | Boston Naming test, animal (semantic) fluency, letter fluency | Impaired verbal fluency | Libon et al. [78], N = 137, NC |
| Visuospatial orientation | Rod Orientation test | Normal | Kolb et al. [38], N = 20, HC, PC |
| Knowledge about object orientation | Object orientation judgements, copying, drawing, and reorienting objects into upright position | Agnosia for object orientation | Robinson et al. [65], N = 1, NC |
| 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], N = 22, HC, BL; Robinson et al. [65], N = 1, UL |
| Letter orientation recognition | Normal (for standard vs. reflected letters and left vs. right side of space) | Reid et al. [58], N = 13 | |
| Body sides differentiation | Identification of indicated body parts (verbally, by touch, or pointing) | Left-right disorientation (9%) | Cohen et al. [71], N = 22, HC, BL |
| Normal | Robinson et al. [65], N = 1, NC, UL | ||
| Imitation of complex movements | Pantomime of indicated motor acts | Ideomotor apraxia (5%) | Cohen et al. [71], N = 22, HC, BL |
| Temporal acuity | Temporal order judgements | Reduced temporal acuity | Bultitude et al. [45], N = 24, HC |
| Alertness | Test of attentional performance | Normal response readiness | Reinersmann et al. [62], N = 12; HC, PC |
| Working memory | Digit span | Impaired working memory span | Libon et al. [78], N = 137, NC |
| Test of attentional performance | Normal continuous updating | Reinersmann et al. [62], N = 12, HC, PC | |
| Spatial working memory | Block tapping test | Normal | Kolb et al. [38], N = 20, HC, PC, right limb |
| Episodic verbal memory and learning | California verbal learning test II | Impaired encoding, recall, and recognition | Libon et al. [78], N = 137, NC |
| Global cognitive processing | 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%) | Libon et al. [78], N = 137, NC |
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. cN 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).