The goal of this clinical trial is to learn if a non-invasive brain stimulation method called continuous theta burst stimulation (cTBS) can improve attention in adults who have hemispatial neglect after stroke. Hemispatial neglect is a common consequence of stroke where a person fails to notice things on one side of their environment and body after brain damage despite having intact sensory organs. Current treatments include physiotherapy, occupational therapy, and visual scanning training. The main questions it aims to answer are: * Does cTBS applied to the cerebellum shift spatial attention toward the neglected side, as measured by eye movements during a visual exploration task? * Does cTBS change brain activity patterns linked to attention networks, as measured by EEG? Researchers will compare different conditions, cerebellar cTBS, cerebral cTBS and sham cTBS to see which approach best improves visuospatial attention. Sham cTBS looks and feels identical to real stimulation but does not deliver effective magnetic pulses. Participants, who are already admitted to the neurology and neurorehabilitation ward, will attend four study visits over approximately two weeks, each lasting about one hour. They receive active or sham cTBS at three stimulation sessions, each separated by at least 48 hours. They also have their eye movements recorded using a camera-based eye-tracking system before and after each session and have their brain activity recorded using EEG, a method that measures electrical activity through small electrodes on the scalp. Participation is voluntary. Participants may withdraw at any time without any impact on their regular medical care. The study is conducted at the Neurocenter of Luzerner Kantonsspital, Switzerland, and is funded by the Swiss National Science Foundation (SNF).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
60
cTBS delivered using a MagPro X100 stimulator with a round coil (MC-125, outer radius 60 mm). Protocol: 801 pulses in 267 bursts (3 pulses at 30 Hz, repeated at 6 Hz). Two trains applied with a 15-minute interval. Targets: left posterior inferior cerebellum (PIC; lobules VI-VIII) and left posterior parietal cortex (PPC), localized by MRI-based neuronavigation (BrainSight). Applied at 100% of individual resting motor threshold.
Sham stimulation delivered using the same MagPro X100 stimulator with a sham coil (MC-P-B70), which produces identical acoustic and tactile sensations as the active coil without delivering effective magnetic stimulation. Same protocol and positioning procedure as active cTBS.
Klinik für Neurologie und Neurorehabilitation
Lucerne, Canton of Lucerne, Switzerland
Mean Gaze Position (MGP) during Free Visual Exploration (FVE)
MGP reflects the mean horizontal position (x-axis) of all fixations during free viewing of 24 naturalistic images. Recorded using an infrared video-based eye tracking system (EyeLink 1000 Plus; 1000 Hz). A MGP of 0 indicates centered fixation distribution; positive values indicate a rightward bias; negative values indicate a leftward shift. Fixations of 100-2000 ms are included. Assessed immediately before and after each cTBS session.
Time frame: pre-intervention and immediatly after intervention
Electroencephalography (EEG)
64-channel scalp EEG recorded before and after each cTBS session (ActiChamp System, Brain Products). Two analysis approaches: (1) microstate analysis assessing global brain states and connectivity patterns; (2) frequency-specific phase synchronization between left and right hemispheres as a measure of interhemispheric connectivity. Impedance kept below 5 kΩ.
Time frame: pre-intervention and immediatly after intervention
MRI-based structural brain connectivity and lesion mapping
Three neuroimaging analyses: (1) Voxel-based lesion-symptom mapping (VLSM) to examine the relationship between lesion location and magnitude of neglect improvement after cTBS; (2) Tractwise proportion analysis assessing lesioned tract proportions of four pathways of interest (cerebello-thalamo-cortical and interhemispheric callosal connections); (3) Correlational tractography using diffusion tensor imaging (DTI) to identify structural connectivity predictors of cTBS response. MRI acquired using a 3T Siemens Verio scanner with 32-channel head coil (MPRAGE T1: TR/TE = 2240/3.72 ms, voxel size 0.9×0.9×0.9 mm).
Time frame: once at baseline
Additional Free Visual Exploration (FVE) variables
Secondary eye-tracking variables derived from the same FVE session as the primary outcome: number of fixations (left vs. right screen half), exploration time (left vs. right screen half), direction of first saccade, and exploration area. Recorded using the EyeLink 1000 Plus System (SR Research; 1000 Hz).
Time frame: pre-intervention and immediatly after intervention
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