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

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.

Study Overview

• Status: Completed
• Conditions: Stroke; Hemianopsia, Homonymous
• Intervention / Treatment: Device: Anodal or sham tDCS; Behavioral: Audio-visual training

• Study Type: Interventional
• Enrollment (Actual): 18
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Italy
  • Lombardia
    • Milan, Lombardia, Italy, 20122
      • Istituto Auxologico Italiano IRCCS

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Anodal Occipital tDCS + audio-visual training; 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; Anodal or sham tDCS (see "Arms") is applied during the execution of an audio-visual training.; Behavioral: Audio-visual training; 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.
Experimental: Anodal Parietal tDCS + audio-visual training; 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; Anodal or sham tDCS (see "Arms") is applied during the execution of an audio-visual training.; Behavioral: Audio-visual training; 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.
Sham Comparator: Sham tDCS + audio-visual training; 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; Anodal or sham tDCS (see "Arms") is applied during the execution of an audio-visual training.; Behavioral: Audio-visual training; 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.

What is the study measuring?

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 "E"s. 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 "E"s. 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

Collaborators and Investigators

• Sponsor: Istituto Auxologico Italiano

Publications and helpful links

General Publications

• Bolognini N, Rasi F, Coccia M, Ladavas E. Visual search improvement in hemianopic patients after audio-visual stimulation. Brain. 2005 Dec;128(Pt 12):2830-42. doi: 10.1093/brain/awh656. Epub 2005 Oct 11.
• Bolognini N, Fregni F, Casati C, Olgiati E, Vallar G. Brain polarization of parietal cortex augments training-induced improvement of visual exploratory and attentional skills. Brain Res. 2010 Aug 19;1349:76-89. doi: 10.1016/j.brainres.2010.06.053. Epub 2010 Jul 1.

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2016
• Primary Completion (Actual): December 31, 2023
• Study Completion (Actual): December 31, 2023

Study Registration Dates

• First Submitted: October 31, 2023
• First Submitted That Met QC Criteria: October 31, 2023
• First Posted (Actual): November 3, 2023

Study Record Updates

• Last Update Posted (Actual): March 12, 2024
• Last Update Submitted That Met QC Criteria: March 8, 2024
• Last Verified: March 1, 2024

More Information

Terms related to this study

• Keywords: tDCS; Hemianopia; Homonymous Visual Field Defects; Compensatory training; Audio-visual multisensory training
• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Eye Diseases; Neurologic Manifestations; Wounds and Injuries; Craniocerebral Trauma; Trauma, Nervous System; Sensation Disorders; Vision Disorders; Blindness; Brain Injuries; Hemianopsia
• Other Study ID Numbers: 25C901

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Individual, anonymized, data will be uploaded on Zenodo.
• IPD Sharing Time Frame: Upon the publication of the study
• IPD Sharing Access Criteria: Access to data will be granted upon request

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No