Anodal tDCS With Compensatory Audio-visual Training for Acquired Visual Field Defects After Brain Injury

Study Overview
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Brief Summary
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Homonymous visual field defects (HVFDs) following acquired brain lesions affect independent living by hampering several activities of everyday life. Available treatments are intensive and week- or month-long. Transcranial Direct current stimulation (tDCS), a plasticity-modulating non-invasive technique, could be combined with behavioral trainings to boost their efficacy or reduce treatment duration. Some promising attempts have been made pairing occipital tDCS with visual restitution training, however less is knows about which area/network should be best stimulated in association with compensatory approaches, aimed at improving exploratory abilities, such as multisensory trainings. In the present double-blind, sham-controlled study, we assess the efficacy of a multisensory training combined with tDCS. 3 groups of participants with chronic HVFDs underwent a 10-day (1.5 hrs/day) compensatory audio-visual training combined with either real anodal tDCS applied to the ipsilesional occipital tDCS (Group 1), or the ipsilesional posterior parietal cortex (Group 2), or a sham, placebo, tDCS (Group 3). The training require the participants to orient their gaze training spatio-temporally congruent, cross-modal, audio-visual stimuli (starting from a central fixation) and press a button as quick as possible upon the detection of the visual stimulus. All stimuli are presented on 2mx2m panel embedded with 48 LEDs and loudspeakers (Bolognini et al., 2010, Brain Research) All participants underwent a neuropsychological assessment of visuospatial functions prior to the beginning of the training (t0), at the end of the training (t1), and at 1-month (t2) and 4-month follow-up (t3). The assessment includes: a visual detection task, three visual search tasks (EF, Triangles, and Numbers; Bolognini et al., 2005, Brain), and a questionnaire about functional impact of the HVFDs in the activities of daily living.

Official Title
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Anodal tDCS With Compensatory Audio-visual Training for Acquired Visual Field Defects After Brain Injury

Conditions
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Stroke, Hemianopsia, Homonymous

Intervention / Treatment
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* Device: Anodal or sham tDCS
* Behavioral: Audio-visual training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: - Presence of chronic (>3 months) HVFD according to Neurophtalmological evaluation, due to acquired brain injury (i.e., stroke, traumatic brain injury, brain tumor) Exclusion Criteria: Presence of hemispatial neglect (indexed by pathological asymmetries on paper-and-pencil tests) Disorders of conjugated eye movements Other neurological disorders (e.g., dementia) Exclusion criteria for brain stimulation (i.e., epilepsy or family history of epilepsy; implanted electrodes, stimulators, pacemakers, infusion pumps, or any implanted metal device; pregnancy)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Three groups of participants were allocated to three different experimental treatments: Group 1: audio-visual training + ipsilesional occipital tDCS Group 2: audio-visual training + ipsilesional posterior parietal tDCS Group 3: audio-visual training + sham, placebo tDCS
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Anodal Occipital tDCS + audio-visual training<br>Anodal tDCS on ipsilesional occipital cortex. Anode electrode placed on O1/O2 (10-20 EEG system) and reference electrode placed on the contralateral forehead. Stimulation delivered at 2mA during the first 30 minutes of the audio-visual training. | Device: Anodal or sham tDCS<br>* Anodal or sham tDCS (see Arms) is applied during the execution of an audio-visual training.<br>Behavioral: Audio-visual training<br>* 90 min/day x 10 days. Participants are seated in front of a 2 m × 2 m training board, at a distance of 1.2 m, in a dimly lit room. The board features 48 red light-emitting diodes (LED, diameter 1 cm, luminance 90 cd m2), distributed in six horizontal rows (eight lights per row). Forty-eight piezoelectric loudspeakers (0.4 W, 8Ω) are located above each light, producing a white-noise (80 dB, duration 100 ms). Spatio-temporally congruent, cross-modal, audio-visual stimuli are presented at one out of 48 possible positions on the board. Participants are instructed to look at the fixation point - at the center of the apparatus - and to move their eyes to detect the presence of the visual stimulus (duration=100 ms) by pressing right button of a wireless mouse.<br>|
| Experimental: Anodal Parietal tDCS + audio-visual training<br>Anodal tDCS on ipsilesional posterior parietal cortex. Anode electrode placed on P3/P4 (10-20 EEG system) and reference electrode placed on the contralateral forehead. Stimulation delivered at 2mA during the first 30 minutes of the audio-visual training. | Device: Anodal or sham tDCS<br>* Anodal or sham tDCS (see Arms) is applied during the execution of an audio-visual training.<br>Behavioral: Audio-visual training<br>* 90 min/day x 10 days. Participants are seated in front of a 2 m × 2 m training board, at a distance of 1.2 m, in a dimly lit room. The board features 48 red light-emitting diodes (LED, diameter 1 cm, luminance 90 cd m2), distributed in six horizontal rows (eight lights per row). Forty-eight piezoelectric loudspeakers (0.4 W, 8Ω) are located above each light, producing a white-noise (80 dB, duration 100 ms). Spatio-temporally congruent, cross-modal, audio-visual stimuli are presented at one out of 48 possible positions on the board. Participants are instructed to look at the fixation point - at the center of the apparatus - and to move their eyes to detect the presence of the visual stimulus (duration=100 ms) by pressing right button of a wireless mouse.<br>|
| Sham Comparator: Sham tDCS + audio-visual training<br>Arm 3: sham tDCS. Half of participants with Group 1 montage, the other half with Group 2 montage. Stimulator is turned off after 30s of the audio-visual training. | Device: Anodal or sham tDCS<br>* Anodal or sham tDCS (see Arms) is applied during the execution of an audio-visual training.<br>Behavioral: Audio-visual training<br>* 90 min/day x 10 days. Participants are seated in front of a 2 m × 2 m training board, at a distance of 1.2 m, in a dimly lit room. The board features 48 red light-emitting diodes (LED, diameter 1 cm, luminance 90 cd m2), distributed in six horizontal rows (eight lights per row). Forty-eight piezoelectric loudspeakers (0.4 W, 8Ω) are located above each light, producing a white-noise (80 dB, duration 100 ms). Spatio-temporally congruent, cross-modal, audio-visual stimuli are presented at one out of 48 possible positions on the board. Participants are instructed to look at the fixation point - at the center of the apparatus - and to move their eyes to detect the presence of the visual stimulus (duration=100 ms) by pressing right button of a wireless mouse.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in Accuracy on the EF Task | Computerized visual search task. Participants have to search for the target letter F surrounded by distractors Es. Accuracy: the proportion of correct responses (range 0-1). | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 
| Change from baseline in Response Times (RTs) on the EF Task | Computerized visual search task. Participants have to search for the target letter F surrounded by distractors Es. RTs: median search times (seconds) of correct responses. | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 
| Change from baseline in Accuracy on the Triangle Task | Computerized visual search task. Participants have to report the number of triangles (targets) surrounded by square distractors. Accuracy: the proportion of correct responses (range 0-1). | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 
| Change from baseline in RTs on the Triangle Task | Computerized visual search task. Participants have to report the number of triangles (targets) surrounded by square distractors. RTs: median search times (seconds) of correct responses. | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 
| Change from baseline in RTs on the Numbers Task | Computerized visual search task. Participants have to point to numbers (1 to 15) in ascending order. RTs: median search times (seconds). | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 
| Change from baseline in the functional scale assessing the impact of vision loss in everyday life activities | A scale assessing the impact of HVFDs on nine activities of daily living. For each item, the score ranges from 0 (No difficulty) to 4 (Very frequent difficulties). | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline in Accuracy on the Visual Detection Task | Detection of visual stimuli presented on the same panel employed for the training. Accuracy (the proportion of detected stimuli; range 0-1) is calculated for both the sighted and the blind hemifields. | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 
| Change from baseline in RTs on the Visual Detection Task | Detection of visual stimuli presented on the same panel employed for the training. RTs: median search times of the detected stimuli are calculated for both the sighted and the blind hemifields. | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Homonymous Visual Field Defects, Hemianopia, Compensatory training, Audio-visual multisensory training, tDCS