Lay report on new publication: Demeyere, N., & Gillebert C.R. (2019). Ego- and allocentric visuospatial neglect: dissociations, prevalence, and laterality in acute stroke.. Neuropsychology, 33(3), 490–498.
Missing half of space is not the same as missing half of an object
Visuospatial neglect is a neuropsychological condition commonly experienced after stroke, whereby people fail to attend to items on one side. In this large study of 366 acute stroke survivors, we investigated whether impairments in attending one half of space, in relation to ones own body and failing to attend to both sides of an object are both aspects of the same problem, or whether these can occur independently. We further wanted to estimate how often these specific attentional/perceptual problems are present, and whether there were differences for left-sided versus right sided problems. Finally, we briefly looked into recovery rates.
Object versus space based neglect was determined following the Broken Hearts Test in the Oxford Cognitive Screen.
Broken Hearts test. 150 hearts (50 complete, 50 incomplete with a right-sided gap and 50 incomplete with a left-sided gap) are arranged on a page. The task is to cross out all the correct hearts. Note that the grid is not visible on the actual test sheet.
(The Broken Hearts Test is part of the Oxford Cognitive Screen (Demeyere N, Riddoch MJ, Slavkova ED, et al. The Oxford Cognitive Screen (OCS): validation of a stroke-specific short cognitive screening tool. Psychol Assess 2015;27:883–94.). )
We found independence of space based and object based neglect, with 50% of the neglect patients showing ‘only’ space based neglect and 25% ‘only’ object based neglect.
Left-sided space based neglect was more common and more severe than right-sided, though right-sided neglect was still highly common in the acute stroke sample (35%).
At 6 months, in a representative subsample of 160 patients, we found neglect recovery rates to be 81% for space based and and 74% for object based neglect, demonstrating high rates of recovery.
The study very clearly showed visuo-spatial problems in acute stroke to be different in nature in different survivors. Consistently missing one half of your environment is conceptually a very different problem to missing half of an object, placed anywhere around you. Stroke survivors with object neglect only may be failing to see the handle on their cup when it is facing one side, regardless of where the cup may be placed (even when placed in the ‘good’ side). Findings like these, demonstrating the different mechanisms underlying the non-obvious problems stroke survivors may face, are crucial in ensuring targeted therapies are developed, which need to take into account the nature of the attentional and perceptual problems.