Neuromodulation Through Multisensory Stimulation for Visual Field Deficits in the Subacute Stage of Disease
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18+
SponsorIstituto Auxologico Italiano
About this trial
Homonymous visual field defects (HVFDs) after acquired brain injuries affect daily life by impairing reading, navigation, and social activities, often impacting anxiety and depression. Spontaneous recovery is rare. Rehabilitation approaches include restorative treatments, which aim to expand the visual field through the stimulation of the so-called transition zone, and compensatory strategies, such as audio-visual training (AVT), which combines eye movement exercises with synchronized visual and auditory cues to train oculomotor scanning and overcome the visual field loss. Combining AVT with non-invasive brain stimulation, such as transcranial direct current stimulation (tDCS), may enhance recovery by promoting brain plasticity. Early evidence suggests that tDCS applied to the lesioned visual cortex during AVT can speed and stabilize improvements, potentially also restoring parts of the visual field. However, most studies on AVT have focused on chronic patients, whereas several clinical trials and international guidelines indicate that early treatment of HVFDs in the subacute phase can optimally exploit the window of maximal neural plasticity and prevent secondary degenerative processes, thereby maximizing visual recovery.
In the present randomized clinical trial, we assess the efficacy of a multisensory audio-visual training (AVT) combined with tDCS in patients with subacute HVFDs after stroke (\<3 months post-lesion). Participants are randomly assigned to two groups: AVT combined with real anodal tDCS applied to the lesioned occipital cortex (Group 1), or AVT combined with sham tDCS (Group 2).
The AVT requires participants to orient their gaze toward spatio-temporally congruent, cross-modal audio-visual stimuli (starting from a central fixation) and press a button as quickly as possible upon detecting the visual target. All stimuli are presented on 2mx2m panel embedded with 40 LEDs and loudspeakers (Diana, Casati, Melzi, Marzoli, et al., 2024). The training will be administered for 90 minutes daily over 10 consecutive days.
All participants underwent a neuro-ophthalmological evaluation and neuropsychological assessment of visuospatial functions before the beginning of the training (t0), at the end of the training (t1), at 2 months (t2) and after 1 year (t3).
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
None
Disqualifiers
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)
Trial design
Design model
Parallel
Treatments tested in this trial
tDCS
DeviceAnodal or sham tDCS (see "Arms") is applied during the execution of an audio-visual training.
Audio-visual training
Behavioral90 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.
Treatment groups
48 Participants
are divided into 2 treatment groupsGroup A: Anodal Occipital tDCS + audio-visual trainingExperimental treatment 2 interventions
Group B: Sham tDCS + audio-visual trainingSham comparator 2 interventions
Trial outcomes
Primary outcomes
1
Change from baseline in Humphrey Visual Field perimetry
Mean Deviation (MD) values of both eyes will be averaged and used for the analyses. Negative values will reflect a deviation from the expected performance in the participant's age group, hence a visual field defect.
Time frame
At baseline (at the beginning of the treatment), at the end of the treatment, at 2- and 12-month follow-upsSecondary outcomes
1
Change from baseline in Accuracy and reaction time 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). RTs: median search times (seconds) of correct responses.
Time frame
At baseline (at the beginning of the treatment), at the end of the treatment, at 2- and 12-month follow-ups2
Change from baseline in Accuracy and Reaction times 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). RTs: median search times (seconds) of correct responses.
Time frame
At baseline (at the beginning of the treatment), at the end of the treatment, at 2- and 12-month follow-ups3
Change from baseline in Accuracy and RTs 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. RTs: median search times of the detected stimuli are calculated for both the sighted and the blind hemifields.
Time frame
At baseline (at the beginning of the treatment), at the end of the treatment, at 2- and 12-month follow-ups4
Change in retinal layers thickness assessed with Spectral Domain Optical Coherence Tomography
Non-invasive medical imaging technique that uses light waves to create high-resolution, cross-sectional pictures (tomograms) of retinal layers. We will assess the peripapillary retinal nerve fiber and the macular ganglion cell complex layers
Time frame
At baseline (at the beginning of the treatment), at 2- and 12-month follow-upsSponsors and contacts
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Source ClinicalTrials.gov