We aim to determine if targeted high-definition transcranial direct current stimulation (HD-tDCS) can safely correct errors in visual verticality perception in patients after stroke affecting either hemisphere.
This study explores a new approach to treat graviceptive neglect, a condition that affects balance and perception of uprightness, using a non-invasive brain stimulation technique called HD-tDCS (high-definition transcranial direct current stimulation). Using a phase I/II randomized sham-controlled double-blind parallel clinical trial design, we aim to analyze if HD-tDCS can safely help correct abnormal visual verticality perception in 28 people after stroke. We will also investigate the effects of our protocol on cerebrovascular response using transcranial Doppler and cortical activity using EEG. Neuroanatomical characteristics will be analyzed to establish the relationship between verticality perception error and the extent of temporo-parietal junction (TPJ) damage and, more broadly, the putative VV structural brain Network (VVN). Each participant will receive six HD-tDCS sessions of 2mA for 20 minutes in a central cathode montage applied over the contralesional TPJ. Patients will be randomized into two groups, with 50% receiving active stimulation and 50% receiving sham stimulation. The sham stimulation condition will consist of the same electrode placement, with a 2mA ramp-up over 30 seconds, followed by a 30-second ramp-down. Both groups will undergo 6 sessions, three times a day, for 2 days. The follow-up assessment will be performed 1 month after stimulation.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
28
Active high-definition transcranial direct current stimulation (HD-tDCS) will be delivered by a low-intensity direct current stimulator (Soterix Medical) using a 3x1 ring configuration with a central cathode over the contralesional temporo-parietal junction. During the stimulation, participants will perform tasks to stimulate correct visual verticality perception. Six active HD-tDCS sessions of 2mA for 20 minutes HD-tDCS, 3 times daily for 2 days with session intervals greater than 3 hours.
Six sessions (3 times daily for 2 days) of 2mA sham HD-tDCS cathode center over the contralesional TPJ for 20min. Direct current (DC) will be generated by a low-intensity direct current stimulator (Soterix Medical) and then split into the 3 high-density Ag/AgCl sintered ring electrodes. The sham stimulation condition will consist of the same positioning of the electrodes as the active condition, with a ramp-up to 2mA over 30 seconds and a subsequent ramp-down of 30 seconds.
Ribeirão Preto Medical School, University of São Paulo
Ribeirão Preto, São Paulo, Brazil
RECRUITINGUniversity of São Paulo, Ribeirão Preto Medical School
Ribeirão Preto, São Paulo, Brazil
NOT_YET_RECRUITINGVisual Verticality Perception (VV; visual graviceptive neglect)
Change in VV: assessment using the bucket method.
Time frame: From baseline (before the first session) to 1 day post-intervention protocol (after six HDtDCS sessions).
Visual Verticality Perception (VV; visual graviceptive neglect)
Change in VV: assessment using the bucket method.
Time frame: From baseline (before the first session) to 30±5 days post-intervention protocol (after six HDtDCS sessions).
Ocular torsion
Change in ocular torsion: assessment using fundus photography (Phelcom; Eyer 1 device)
Time frame: From baseline (before the first session) to 1 day post-intervention protocol (after six HDtDCS sessions).
Ocular torsion
Change in ocular torsion: assessment using fundus photography (Phelcom; Eyer 1 device)
Time frame: From baseline (before the first session) to 30±5 days post-intervention protocol (after six HDtDCS sessions).
Electroencephalography
Electroencephalography measurements focusing on resting state networks related to visual verticality perception.
Time frame: From baseline (before the first session) to 1 day post-intervention protocol (after six HDtDCS sessions).
Electroencephalography
Electroencephalography measurements focusing on resting state networks related to visual verticality perception.
Time frame: From baseline (before the first session) to 30±5 days post-intervention protocol (after six HDtDCS sessions).
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Cerebrovascular reactivity
Transcranial Doppler Ultrasonography (TCD; Viasonix Dolphin/XF Robot) will be employed to measure cerebral blood flow velocity in the middle cerebral arteries while the participant performs the breath-holding maneuver.
Time frame: From baseline (before the first session) to 1 day post-intervention protocol (after six HDtDCS sessions).
Cerebrovascular reactivity
Transcranial Doppler Ultrasonography (TCD; Viasonix Dolphin/XF Robot) will be employed to measure cerebral blood flow velocity in the middle cerebral arteries while the participant performs the breath-holding maneuver.
Time frame: From baseline (before the first session) to 30±5 days post-intervention protocol (after six HDtDCS sessions).
Spatial neglect
Spatial neglect will be assessed using the conventional Behavior Inattention Test (BIT), which consists of 6 items: 1) line crossing; 2) letter cancellation; 3) star cancellation; 4) figure and shape copying; 5) line bisection; and 6) representational drawing.
Time frame: From baseline (before the first session) to 1 day post-intervention protocol (after six HDtDCS sessions).
Spatial neglect
Spatial neglect will be assessed using the conventional Behavior Inattention Test (BIT), which consists of 6 items: 1) line crossing; 2) letter cancellation; 3) star cancellation; 4) figure and shape copying; 5) line bisection; and 6) representational drawing.
Time frame: From baseline (before the first session) to 30±5 days post-intervention protocol (after six HDtDCS sessions).