Reduced Visuospatial Attention in Personal Space is Not Limited to the Affected Limb in Complex Regional Pain Syndrome

Abstract

Purpose

Alterations in spatial attention have been reported in people with chronic pain and may be relevant to understanding its cortical mechanisms and developing novel treatments. There is conflicting evidence as to whether people with Complex Regional Pain Syndrome (CRPS) have reduced visuospatial attention to their affected limb and/or its surrounding space, with some evidence that these deficits may be greater in personal (bodily) space. We aimed to test the competing hypotheses of whether the visuospatial attentional bias is specific to the personal space of the affected limb or generalizes to the personal space of other parts of the affected side of the body.

Patients and Methods

Using visual Temporal Order Judgement tasks, we measured spatial attention in the personal space of the hands and feet of patients with upper (n=14) or lower (n=14) limb CRPS and pain-free controls (n=17). Participants judged the order of two light flashes presented at different temporal offsets on each of their hands or feet. Slower processing of the flash on one side relative to the other reflects reduced attention to that side of space.

Results

Controls prioritized stimuli on the non-dominant (left) relative to dominant side, consistent with the well-documented normal leftward bias of attention (ie “pseudoneglect”). Regardless of the location (upper or lower limb) of the pain or visual stimuli, people with CRPS showed no such asymmetry, representing reduced attention to the affected side (compared to the greater attention of controls to their non-dominant side). More severe CRPS symptoms were associated with a greater tendency to deprioritize stimuli on the affected side.

Conclusion

Our findings suggest that relative visuospatial bias in CRPS is generalized to the personal space of the affected side of the body, rather than being specific to the personal space of the CRPS-affected limb.

Keywords:

• complex regional pain syndrome
• spatial attention
• personal space
• pseudoneglect
• temporal order judgement
• chronic pain

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This study was supported by a Research Support Fund from the University of Bath to Monika Halicka, and a grant from the Reflex Sympathetic Dystrophy Syndrome Association to Janet H Bultitude and Michael J Proulx. Monika Halicka is supported by the Fund for Scientific Research of the French-speaking Community of Belgium (F.R.S.-FNRS). Antonia F Ten Brink was supported by a Rubicon grant (019.173SG.019) from the Netherlands Organisation for Scientific Research. Axel D Vittersø was supported by the GW4 BioMed Medical Research Council Doctoral Training Partnership (1793344). The funders had no role in study design; collection, analysis and interpretation of data; writing the report; the decision to submit the article for publication.