Spatial neglect is a frequent and disabling attentional disorder after stroke, characterized by reduced detection, orientation, or response to stimuli on the contralesional side. The condition is not attributable to primary sensory or motor deficits and affects roughly 30–50% of stroke survivors. Consequences include impaired mobility, difficulties with navigation and reading, reduced ability to perform activities of daily living (ADLs) such as dressing and eating, loss of independence, longer hospital stays, and higher readmission rates. An estimated proportion of affected individuals progresses to chronic neglect, increasing caregiver reliance and potentially contributing to anxiety, depression, and fatigue.
Prism adaptation (PA) is a bottom-up rehabilitation approach that does not rely on patient insight into deficits, making it suitable for patients with reduced awareness (anosognosia), which has been reported in up to 64% of individuals with neglect. In PA, participants wear prism goggles that shift the visual field rightward and repeatedly reach to visual targets. Initial rightward pointing errors occur; with repetitive reaching, participants adapt and subsequently display therapeutic after-effects—a leftward shift in pointing when prisms are removed—that are associated with reductions in neglect severity and, in some studies, improvements in functional outcomes.
Two processes are proposed to underlie PA-induced after-effects: strategic recalibration and spatial realignment. Strategic recalibration involves conscious correction for pointing errors and occurs rapidly, whereas spatial realignment represents a slower, unconscious remapping of proprioceptive and visual spatial representations. To favour development of after-effects, standard PA procedures typically minimize strategic recalibration (for example, by occluding view of the hand during pointing).
Although PA has advantages—brief daily administration (10–15 minutes), limited reliance on patient strategy, and the potential for functional gains—its clinical implementation faces barriers. Traditional protocols can be repetitive and poorly engaging, require specialized equipment such as occlusion boards, and generally need clinician supervision in hospital or research settings, imposing travel and resource burdens. Moreover, prior randomized trials using small prism shifts (5–6°) or sham goggles often found no significant therapeutic effects, whereas studies employing prism shifts of at least 10° reported more consistent improvements. The absence of standardized protocols and variability across studies have contributed to inconsistent evidence for PA efficacy.
The EMPATH study is a longitudinal, double-blind, quasi-randomized, controlled trial designed to evaluate an engaging, mobile, computerized PA procedure for treating spatial neglect in inpatient and community/home settings. The trial will enroll 42 individuals with right-hemisphere stroke who exhibit mild to severe neglect symptoms. Participants will be quasi-randomized into two arms: an active intervention using Peg-the-Mole with 15° rightward-deviating prism goggles, or an active control using Peg-the-Mole with 5° rightward-deviating prism goggles.
Blinded outcome assessments are scheduled immediately before treatment, immediately after the two-week treatment period, and at a one-month follow-up.
Peg-the-Mole is a gamified, computerized adaptation of PA intended to increase engagement and enable delivery in both inpatient and home/community environments. Each participant completes 10 sessions over 2 weeks, with each session involving 15 minutes of Peg-the-Mole practice while wearing the assigned prism goggles. The intervention arm uses a 15° rightward visual shift, a magnitude chosen because prior evidence indicates that shifts of at least 10° are more likely to produce therapeutic benefits; the control arm uses a 5° shift, aligned with prior studies that reported minimal clinical effects with small shifts.
The primary outcome is performance on the Star Cancellation subtest of the Behavioural Inattention Test. Secondary measures include other conventional and behavioural subtests of the Behavioural Inattention Test, one subtest from the Eschenbeck Standardized Activities of Daily Living battery, the Halifax Neglect Impact Scale (caregiver- and self-report), measures of feasibility and acceptability for the intervention, objective measurement of prism adaptation after-effects, and self-report scales for mood and fatigue (Hospital Anxiety and Depression Scale and Fatigue Severity Scale).
Assessments are planned at baseline (pre-treatment), immediately post-treatment, and at one-month follow-up to evaluate short-term and sustained effects.
A central aim of the protocol is to evaluate whether a gamified, portable PA procedure can improve treatment accessibility and adherence and be implemented in both inpatient and community settings. The study will collect feasibility and acceptability data alongside clinical outcomes. Given clinical data sensitivity, the authors state that only group-level data will be available on request; the study protocol itself will be publicly accessible.
The trial is registered at ClinicalTrials.gov (Identifier: NCT05595668; registration date October 27, 2022). Funding is provided by the Nova Scotia Health Research Fund. The authors declare no competing interests. The published protocol notes that the funders had no role in study design, data collection and analysis, decision to publish, or manuscript preparation.
The EMPATH protocol tests whether a mobile, engaging PA delivery (Peg-the-Mole) can overcome practical barriers of conventional PA—namely, limited accessibility, repetitive tasks that reduce engagement, and the need for specialized equipment and clinician supervision—while maintaining a therapeutic prism shift sufficient to induce beneficial after-effects. If effective and acceptable, the intervention could expand PA delivery into home and rehabilitation settings, potentially improving neglect symptoms, functional independence, and quality of life for stroke survivors.
The protocol acknowledges that prior evidence is inconsistent and that prism shift magnitude appears important; thus the trial compares a 15° intervention dose with a 5° active control. The study's outcomes will inform whether a standardized, portable PA protocol can be implemented widely and whether gamified approaches improve adherence and functional outcomes in individuals with post-stroke spatial neglect.
Note: The source is a study protocol; no trial results or effect sizes are reported in the source document.