Anatomical predictors of successful prism adaptation in chronic visual neglect

Abstract

Visual neglect is a frequent and disabling consequence of right hemisphere damage. Previous work demonstrated a probable role of posterior callosal dysfunction in the chronic persistence of neglect signs. Prism adaptation is a non-invasive and convenient technique to rehabilitate chronic visual neglect, but it is not effective in all patients. Here we aimed to assess the hypothesis that prism adaptation improves left neglect by facilitating compensation through the contribution of the left, undamaged hemisphere. We assessed the relationship between prism adaptation effects, cortical thickness and white matter integrity in a group of 14 patients with unilateral right-hemisphere strokes and chronic visual neglect. Results showed that patients who benefitted from prism adaptation had thicker cortex in temporo-parietal, prefrontal and cingulate areas of the left, undamaged hemisphere. Additionally, these patients had a higher fractional anisotropy value in the body and genu of the corpus callosum. Results from normal controls show that these callosal regions connect temporo-parietal, sensorimotor and prefrontal areas. Finally, shorter time intervals from the stroke tended to improve patients' response to prism adaptation. We concluded that prism adaptation may improve left visual neglect by promoting the contribution of the left hemisphere to neglect compensation. These results support current hypotheses on the role of the healthy hemisphere in the compensation for stroke-induced, chronic neuropsychological deficits, and suggest that prism adaptation can foster this role by exploiting sensorimotor/prefrontal circuits, especially when applied at early stages post-stroke.

Disconnection somewhere down the line: Multivariate lesion-symptom mapping of the line bisection error

“…Correspondingly, a recent intervention study using inhibitory continuous theta burst stimulation (cTBS) over the contralesional parietal lobe found integrity of posterior parts of the corpus callosum to be predictive for successful treatment of directional attentional biases (Nyffeler et al, 2019). Indeed, reduced callosal integrity has been found to be a predictor of persistent attentional deficits in the chronic stage (Lunven et al, 2015), as diagnosed amongst other tests with the line bisection task and leading to persistent symptoms even after therapeutic intervention by prism adaption (Lunven et al, 2019).…”

White matter variability, cognition, and disorders: a systematic review.

“…While some methodological re nement is needed in the eld of white matter tractography (Wasserthal et al, 2018;Maier-Hein et al, 2017), preliminary evidence indicates that variations in white matter anatomy can show disease progression or explain differential patterns of symptoms (Forkel et al, 2020). Differences in brain connections can also shed light on why current invasive and non-invasive treatments and therapies help some but not all patients (Lunven et al, 2019;Parlatini et al, under review;Sanefuji et al, 2017). These ndings are encouraging, as we move towards more personalised approaches to medicine.…”

White matter variability, cognition, and disorders: a systematic review

“…While some methodological refinement is needed in the field of white matter tractography (Wasserthal et al, 2018; Maier-Hein et al, 2017), preliminary evidence indicates that variations in white matter anatomy can show disease progression or explain differential patterns of symptoms (Forkel et al, 2020). Differences in brain connections can also shed light on why current invasive and non-invasive treatments and therapies are helping some but not all patients (Lunven et al, 2019; Parlatini et al, under review; Sanefuji et al, 2017). These findings are encouraging, as we move towards personalised medicine.…”

“…Wasserthal et al, 2018; Maier-Hein et al, 2017; Grisot et al 2021), preliminary evidence indicates that differences in white matter phenotypes are beginning to explain disease progression and differential symptom presentations (Forkel et al, 2020). Variability in structural brain connections can also shed light on why current invasive and non-invasive treatments and therapies help some but not all patients (Lunven et al, 2019; Parlatini et al, under review; Sanefuji et al, 2017). These findings are encouraging, as we move towards more personalised approaches to medicine.…”