Visuospatial neglect is a common neurological symptom which appears following strokes on regions of the right hemisphere of the brain. It affects patient's self representation and awareness of the space, impairing functional rehabilitation and adaptation back to a normal life. The primary purpose of this protocol is to assess the impact of 10 daily sessions of a non-invasive brain stimulation technique, low frequency repetitive Transcranial Magnetic Stimulation (rTMS), applied on the intact hemisphere of the brain to treat post stroke visuospatial neglect at the chronic stage. The hypothesis is that a regime of real but not sham rTMS on the left posterior parietal cortex of the brain will long-lastingly ameliorate visuospatial neglect in stroke patients as revealed by clinical paper-and-pencil and computer-based tests assessing search, detection and discrimination of stimuli presented in different areas of the visual field.
Scientific aims and goals:
The long-term goal aim of this application is to provide evidence of the role of a non-invasive neuromodulation technique such as rTMS in the treatment of chronic neurological sequels generated after strokes in human patients. Such interventions are based in an "at will" modulation the level of activity in intact regions, resulting in an enhancement of excitatory projections or the suppression of inhibitory influences driven through spared connectivity. They result in activity increases of the stroke surviving neurons, allowing the re-emergence of function after brain damage. Such principles can be applied to different sorts of neurological sequels for which the underlying connectivity and its post-stroke status is well known. In this specific project, we propose the use of low frequency rTMS on the intact left posterior parietal cortex (in the intraparietal sulcus, IPS) to improve the symptoms of visuospatial neglect derived form right stroke injuries including the posterior parietal cortex. Such project is based in the interhemispheric rivalry hypothesis, according to which, spatial neglect is in part caused by the over inhibition exerted from the intact left parietal cortex onto the injured left homologue regions, which are mediated by well-known overall inhibitory transcallosal projections between the left and the right hemispheres. According to this hypothesis and preliminary data, the reduction of the left parietal disinhibition should result into a lesser degree of suppression exerted by the intact left hemisphere sites onto the right injured parietal areas, process which will along the emergence of activity.In this context, we defined a primary aim accompanied by two secondary aims, which will be tackled in parallel:Primary AIMS AIM1: To assess the effects of repetitive Transcranial Magnetic Stimulation (rTMS) in the treatment of chronic visuospatial neglect generated by stroke Secondary AIMS AIM 2: To assess the durability of such a recovery over time once the treatment is completed and discontinued AIM 3: To further assess the safety of such therapeutic approach based in the deactivation of an intact -but hyperexcited region- holding connectivity with the damaged area.
Evaluation criteria Main criteria -Changes in the Spatial Bias Compound Score (SBCS) between pre (baseline) and post 10 days of rTMS treatment Such score is calculated on the basis of the result of 4 subtests which include: (1) bells cancellation task, (2) a copy of the GAINOTTI figure, (3) identification of overlapping figures, and (4) line bisection, according to the following formula (SBCS=λ=ln(XR/XL), considering the identification or copying of elements presented on the right or the left visual fields of the patient. The subtests of the SBCS will be also individually assessed and followed.
1. Efficacy criteria
2. Safety criteria
3. Predictive factors assessmentStudy population and duration of studyWe will study a population of stroke patients with chronic signs of hemispatial neglect with at least 3 months of evolution (n=148, 2 groups of 74 patients) recruited across 48 months at an approximate rate of 37 patients /year.
- Real rTMS Device
Intervention Desc: Transcranial Magnetic Stimulation, in a low frequency (1 Hz) continuous train of 20 minutes (1200 pulses) ARM 1: Kind: Experimental Label: 1: Real rTMS treatment Description: Transcranial Magnetic Stimulation, in a low frequency (1 Hz) continuous train of 20 minutes (1200 pulses)
- Sham rTMS Device
Intervention Desc: two TMS coils will be used: a passive one which is placed flat on top of the "actively" targeted region which remains unplugged and generates a continuous scalp tactile sensation, and an active one located at a prudential distance from the scalp, which will deliver active pulses and its accompanying sensations ARM 1: Kind: Experimental Label: 2: Sham rTMS treatment Description: Simulation of rTMS
- Allocation: Randomized
- Masking: Double Blind (Subject, Investigator)
- Purpose: Treatment
- Endpoint: Safety/Efficacy Study
- Intervention: Parallel Assignment
|Type||Measure||Time Frame||Safety Issue|
|Primary||Changes in the Spatial Bias Compound Score (SBCS). Such score is calculated on the basis of the result of 4 subtests||between pre (baseline) and post 10 days of rTMS treatment||No|
|Secondary||Changes in Catherine BERGEGO Scale and-or equivalent ecological test||between pre (baseline) and every subsequent evaluation||No|
|Secondary||Changes in the percentage of correct target detections vs. total||between pre (baseline) and every subsequent evaluation||No|
|Secondary||Changes in the Normalized reaction time of correct detections||between pre (baseline) and every subsequent evaluation||No|
|Secondary||potential clinically relevant side-effect caused by the use of TMS in terms of neurological manifestations such as: seizure, occurrence of additional stroke, or signs of enhanced intracranial pressure.||During rTMS treatment and the 6 months follow-up||Yes|
|Secondary||changes in cognitive functions processed by the intact left parietal cortex||between baseline and every subsequent evaluation, during the 6 months follow-up||Yes|
|Secondary||Changes of the main cognitive domains and depression status according to the Mini-Mental test and Hamilton depression scale||between pre (baseline) and every subsequent evaluation||Yes|
|Secondary||Correlation between treatment efficacy and lesion location and extent||Any time after the end of rTMS treatment||No|
|Secondary||Correlation between treatment efficacy and severity of Neglect and other associated clinical deficits||Any time after the end of rTMS treatment||No|
|Secondary||Correlation between treatment efficacy and rTMS parameters and patient's cortical excitability and sensations||Any time after the end of rTMS treatment||No|
|Secondary||Correlation between treatment efficacy and daily activities with potential impact on Neglect||Any time after the end of rTMS treatment||No|
|Secondary||Evaluation of SBCS and its subscores at each follow-up visits||5 days, 10 days, 15 days, 20 days, 27 days, 40 days, 70 days, 130 days and 190 days after 1st rTMS session.||No|
|Secondary||Changes in neurological conditions according to: Rankin, Barthel and NIH SS scores||Between baseline and every subsequent evaluation||Yes|