Transcranial Stimulation (tDCS) and Prism Adaptation in Spatial Neglect Rehabilitation

Recruiting

Phase N/A Results N/A

Trial Description

The present study aims to compare the relative therapeutic efficacy of prism adaptation therapy combined with real versus sham tDCS. The investigators will test the hypothesis that the magnitude and duration of neglect improvement will be increased when prism therapy is combined with real tDCS compared to sham tDCS.
A second objective is to test whether individual differences in baseline clinical or brain imaging measures can predict: 1) neglect severity or 2) inter-individual differences in patients' therapeutic response.
A third goal is to use brain imaging to characterize the patterns of neural change induced by the intervention to identify brain structures that mediate therapeutic response.

Detailed Description

'Neglect' is a common neurological syndrome that affects approximately 50% of right-hemisphere stroke patients. It is a complex multi-faceted syndrome, but its core defining feature is that patients lose the capacity to voluntarily control attention in the left half of space. Neglect has a significant debilitating effect on patients' functional independence and everyday life and indicates a poor prognosis for long-term functional recovery.
To date, there is no effective rehabilitation intervention available for routine clinical use. One of the most promising experimental strategies for neglect rehabilitation is prism adaptation, a form of motor training that induces short-lived improvements in a variety of cognitive domains. However, its major limitation is that the benefits are transient. The investigators aim to test the hypothesis that by combining prism therapy with transcranial direct current stimulation (tDCS), this will boost learning/memory processes, resulting in larger and longer-lasting therapeutic effects.
The investigators will conduct a randomized controlled clinical trial to test the efficacy of multi-session prism therapy combined with real versus sham tDCS for the rehabilitation of chronic post-stroke neglect. Baseline neuroimaging data will be used as predictor variables to explain inter-individual variation in therapeutic response. Contrasts between pre- and post-intervention imaging data will be performed to identify neural structures that mediate therapeutic effects.

Conditions

Interventions

  • Anodal tDCS Device
    Intervention Desc: Participants will receive 1mA anodal tDCS over the left primary motor cortex. The active (positive) electrode will be centered on the scalp overlying the primary motor cortex and the reference (negative) electrode will be placed over the contralateral supraorbital ridge. The stimulation will last 20 minutes and run concurrent with the duration of the prism adaptation therapy.
    ARM 1: Kind: Experimental
    Label: Prism adaptation + anodal tDCS
    Description: Participants will receive 1 milliamp (mA) anodal tDCS over the left primary motor cortex concurrent with a 20-minute session of prism adaptation. They will undergo 5 consecutive daily sessions.
  • Sham tDCS Device
    Intervention Desc: Participants will receive 1mA sham tDCS over the left primary motor cortex. The active (positive) electrode will be centered on the scalp overlying the primary motor cortex and the reference (negative) electrode will be placed over the contralateral supraorbital ridge. The stimulation will last 20 minutes and run concurrent with the duration of the prism adaptation therapy.
    ARM 1: Kind: Experimental
    Label: Prism Adaptation + Sham tDCS
    Description: Participants will receive Sham tDCS over the left primary motor cortex concurrent with a 20-minute session of prism adaptation. They will undergo 5 consecutive daily sessions.
  • Prism adaptation Behavioral
    Intervention Desc: All participants will undergo prism adaptation, a form of behavioural therapy involving reaching and pointing movements while wearing glasses that induce an optical shift.
    ARM 1: Kind: Experimental
    Label: Prism adaptation + anodal tDCS
    Description: Participants will receive 1 milliamp (mA) anodal tDCS over the left primary motor cortex concurrent with a 20-minute session of prism adaptation. They will undergo 5 consecutive daily sessions.
    ARM 2: Kind: Experimental
    Label: Prism Adaptation + Sham tDCS
    Description: Participants will receive Sham tDCS over the left primary motor cortex concurrent with a 20-minute session of prism adaptation. They will undergo 5 consecutive daily sessions.
    ARM 3: Kind: Experimental
    Label: Prism adaptation + no tDCS
    Description: Participants will receive no tDCS at all but will undergo a 20-minute session of prism adaptation. They will undergo 5 consecutive daily sessions.

Trial Design

  • Allocation: Randomized
  • Masking: Double Blind (Subject, Investigator)
  • Purpose: Treatment
  • Endpoint: Efficacy Study
  • Intervention: Crossover Assignment

Outcomes

Type Measure Time Frame Safety Issue
Primary Behavioural Inattention Test (BIT) Assessed at the recruitment interview (week 0) and at the exit interview (8 weeks after the intervention) No
Primary Neglect Test Battery Assessed at 2 separate pre-intervention baseline sessions at least 1 week apart. Re-assessed following the intervention at intervals of 1, 2, 4 and 8 weeks. No
Secondary Changes in brain imaging data Change in a range of MRI measures between one baseline pre-intervention scan and the post-intervention scan (+ 5 weeks) No

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