Hemispatial Neglect, Visual Neglect, Stroke
Conditions
Keywords
Neglect, Stroke, cTMS, Cerebellum
Brief summary
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).
Interventions
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.
Sponsors
Luzerner Kantonsspital
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Caregiver)
Intervention model description
randomized, sham-controlled, single-blinded crossover design
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* First-ever, subacute right hemispheric stroke * Left-sided visual neglect defined by MGP \> 1.333° * Age ≥18 years * Normal or corrected-to-normal visual acuity * MRI compatibility (MRI-based neuronavigation for cTBS) * Capacity to consent and ability to follow study procedures
Exclusion criteria
* Cerebellar lesion * History of epilepsy * Metallic implants in the head region * Scalp or skin conditions that interfere with EEG electrode placement (e.g. open wounds, infections, severe psoriasis) * Co-morbidities including: neurological, degenerative or major psychiatric disorder (other than index stroke), alcohol or drug abuse, severe liver or kidney disease, and active malignant tumor disease * Pregnancy * Enrolment in an ongoing clinical trial
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Mean Gaze Position (MGP) during Free Visual Exploration (FVE) | pre-intervention and immediatly after intervention | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Electroencephalography (EEG) | pre-intervention and immediatly after intervention | 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. |
| MRI-based structural brain connectivity and lesion mapping | once at baseline | 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). |
| Additional Free Visual Exploration (FVE) variables | pre-intervention and immediatly after intervention | 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). |
Countries
Switzerland
Contacts
CONTACTThomas Nyffeler, Prof. Dr. med.
Outcome results
None listed