Non-Spatial Impairments Affect False-Positive Neglect Diagnosis Based on Cancellation Tasks

Abstract

Objective: To diagnose egocentric neglect after stroke, the spatial bias of performance on cancellation tasks is typically compared to a single cutoff. This standard procedure relies on the assumption that the measurement error of cancellation performance does not depend on non-spatial impairments affecting the total number of cancelled targets. Here we assessed the impact of this assumption on false-positive diagnoses. Method: We estimated false positives by simulating cancellation data using a binomial model. Performance was summarised by the difference in left and right cancelled targets (R-L) and the Centre of Cancellation (CoC). Diagnosis was based on a fixed cutoff versus cutoffs adjusted for the total number of cancelled targets and on single test performance versus unanimous or proportional agreement across multiple tests. Finally, we compared the simulation findings to empirical cancellation data acquired from 651 stroke patients. Results: Using a fixed cutoff, the rate of false positives depended on the total number of cancelled targets and ranged from 10% to 30% for R-L scores and from 10% to 90% for CoC scores. The rate of false positives increased even further when diagnosis was based on proportional agreement across multiple tests. Adjusted cutoffs and unanimous agreement across multiple tests were effective at controlling false positives. For empirical data, fixed versus adjusted cutoffs differ in estimation of neglect prevalence by 13%, and this difference was largest for patients with non-spatial impairments. Conclusions: Our findings demonstrate the importance of considering non-spatial impairments when diagnosing neglect based on cancellation performance.

Right and left neglect are not anatomically homologous: A voxel-lesion symptom mapping study

“…Previous research has suggested that it is generally best to diagnose neglect based on agreement between multiple or repeated neuropsychological tests as no single J o u r n a l P r e -p r o o f neuropsychological test is perfectly sensitive to neglect impairment (Azouvi et al, 2002;Huygelier et al, 2020;Lindell et al, 2007). Though additional and potentially computerised measures may have provided a more sensitive measure, the acute nature and relatively severe neglect impairments combined with a sensitive cancellation task provides confidence in the methods employed.…”

Aligning formal and functional assessments of Visuospatial Neglect: A mixed-methods study

“…It is plausible that each of these additional neglect subtypes may be associated with distinct patterns of functional impairment. Additionally, previous research has strongly suggested that the most reliable method for detecting and diagnosing visuospatial neglect is requiring agreement between multiple, independent neuropsychological tests (Bowen et al, 1999;Huygelier et al, 2020). However, this recommendation is not commonly followed in clinical settings.…”

The Value of Bayesian Methods for Accurate and Efficient Neuropsychological Assessment

“…The Bayesian framework provides an elegant way to directly answer the question that the clinician wants to To illustrate the difference between both approaches, we assessed how they inform the diagnosis of post-stroke hemispatial neglect using scores on a cancellation task (see Huygelier et al (2020) for details about the study). A cancellation task is a visual search array in which patients are asked to mark certain shapes (targets) and ignore other shapes (distractors).…”

“…A cancellation task is a visual search array in which patients are asked to mark certain shapes (targets) and ignore other shapes (distractors). To diagnose hemispatial neglect according to the traditional approach, the difference in the number of cancelled targets between the left and right side of the cancellation page (R-L score) is compared to two fixed percentile cut-offs, such as the 5 th and 95 th percentile, based on a normative control group (Huygelier et al, 2020). If the R-L score of the patient exceeds either one of these percentiles, neglect is diagnosed (i.e., the alternative hypothesis is confirmed).…”

“…. More details about these data can be found in Huygelier et al (2020). Diagnosis based on the frequentist normative 5 th and 95 th percentiles (A) and the posterior odds assuming a neglect prevalence of 50% (B), 30% (C) and 70% (D).…”