Hemianopsia, Homonymous, Stroke
Conditions
Keywords
Homonymous Visual Field Defects, Hemianopia, Compensatory training, Audio-visual multisensory training, tDCS
Brief summary
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.
Interventions
DEVICEAnodal or sham tDCS
Anodal or sham tDCS (see Arms) is applied during the execution of an audio-visual training.
BEHAVIORALAudio-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.
Sponsors
Istituto Auxologico Italiano
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Masking description
The tDCS device has a built-in function for double blind studies, i.e., the experimenters are not aware whether they are applying real or sham tDCS.
Intervention 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
Eligibility
Sex/Gender
ALL
Age
18 Years to 90 Years
Healthy volunteers
No
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) *
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change from baseline in the functional scale assessing the impact of vision loss in everyday life activities | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 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). |
| Change from baseline in RTs on the Triangle Task | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 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. |
| Change from baseline in RTs on the Numbers Task | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | Computerized visual search task. Participants have to point to numbers (1 to 15) in ascending order. RTs: median search times (seconds). |
| Change from baseline in Accuracy on the EF Task | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 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). |
| Change from baseline in Response Times (RTs) on the EF Task | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 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. |
| Change from baseline in Accuracy on the Triangle Task | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 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). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change from baseline in RTs on the Visual Detection Task | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 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. |
| Change from baseline in Accuracy on the Visual Detection Task | At baseline (at the beginning of the treatment), at the end of the treatment, at 1- and 4-month follow-ups | 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. |
Countries
Italy
Outcome results
None listed