Recent advances in treatment of spatial neglect: networks and neuropsychology

ABSTRACT

Introduction

Spatial neglect remains an underdiagnosed and undertreated consequence of stroke that imposes significant disability. A growing appreciation of brain networks involved in spatial cognition is helping us to develop a mechanistic understanding of different therapies under development.

Areas covered

This review focuses on neuromodulation of brain networks for the treatment of spatial neglect after stroke, using evidence-based approaches including 1) Cognitive strategies that are more likely to impact frontal lobe executive function networks; 2) Visuomotor adaptation, which may depend on the integrity of parietal and parieto- and subcortical-frontal connections and the presence of a particular subtype of neglect labeled Aiming neglect; 3) Non-invasive brain stimulation that may modulate relative levels of activity of the two hemispheres and depend on corpus callosum connectivity; and 4) Pharmacological modulation that may exert its effect primarily via right-lateralized networks more closely involved in arousal.

Expert opinion

Despite promising results from individual studies, significant methodological heterogeneity between trials weakened conclusions drawn from meta-analyses. Improved classification of spatial neglect subtypes will benefit research and clinical care. Understanding the brain network mechanisms of different treatments and different types of spatial neglect will make possible a precision medicine treatment approach.

KEYWORDS:

• Aiming neglect
• brain networks
• neuromodulation
• precision medicine
• prism adaptation
• rehabilitation
• spatial neglect
• stroke
• transcranial magnetic stimulation
• visual scanning

Acknowledgments

Special thanks to all of the people who suffered a stroke and who volunteered their time for studies cited from our laboratory, and to their families. Thanks to the anonymous reviewers who shared valuable comments to improve our review, and to our funding sources.

Article highlights

• The field of stroke rehabilitation is faced with the challenge of linking methods of treatment for spatial neglect to our growing understanding of the underlying brain network pathophysiology.

• Additional studies are required to strengthen the association between cognitive rehabilitation approaches, such as visual scanning for treatment of spatial neglect, and reorganization of frontal lobe networks involved in executive function.

• Prism adaptation therapy may be most effective in individuals with frontal lobe lesions of attention networks, and those that have Aiming neglect symptoms such as ipsilesional rotational behavior.

• Beneficial effects of inhibitory transcranial magnetic stimulation to the contralesional parietal cortex are associated with corpus callosum integrity, and this argues for interhemispheric cooperation in spatial neglect recovery. However, the lack of consistent contralesional parietal hyperactivation argues against a simple interhemispheric rivalry model.

• Pharmacological modulation of spatial awareness can be achieved either by dopaminergic stimulation, which may act through right lateralized arousal systems, or through cholinergic enhancement of general cognitive processes.

• Spatial neglect has been treated as a unitary symptom, however a personalized approach, taking into account factors such as spatial neglect subtype, lesion location, functional and structural attention network connectivity, corpus callosum integrity, and relative levels of activation between the hemispheres, could be used to design more effective precision therapy.

Declaration of interest

The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

AM Barrett is supported by the Veteran Administration and by UMass Medical School and UMass Memorial Healthcare. She also receives grant support from the Veteran Administration Office of Research Development (grant no. 1 I01 RX003662-A1 and 1 I21 RX003760-01). A Carter is also supported by the Washington University School of Medicine.