Brain Injuries, Consciousness Disorder, Minimally Conscious State, Vegetative State
Conditions
Brief summary
This study evaluates the feasibility of an experimental protocol that combines advanced multi-modal imaging of the brain with clinical and behavioural scales to characterise the neural, behavioural, and clinical effects of transcranial direct current stimulation (tDCS) for rehabilitation in PDOC
Detailed description
Patients with prolonged disorders of consciousness (PDOC) have very limited therapeutic options, and they often show little to no progress over time. Here, the investigators will assess whether transcranial direct current stimulation can improve patients' responsiveness. The investigators will use a protocol designed to target specific brain networks that have been shown to play a key role in explaining the lack of voluntary responses in PDOC. The study will focus on characterising the mechanisms of action of tDCS and the bases for potential individual differences in responsiveness to the stimulation across participants. This feasibility study is the first step towards developing personalised tDCS interventions to restore external responsiveness in PDOC patients. Its results will inform the design of a future trial fully powered for characterising neural, behavioural, and clinical effects of tDCS in PDOC as well as the mechanisms underlying individual differences in responsiveness.
Interventions
OTHERTranscranial direct current stimulation
tDCS alters neural excitability in a polarity-specific manner via a weak direct electric current delivered through electrodes placed on the scalp. There are 3 types of stimulation: anodal, cathodal, and sham. In anodal tDCS, the positive electrode is placed over the target brain area to increase neuronal excitability. In cathodal tDCS, the negative electrode is placed over the target brain area to decrease neuronal excitability. Sham tDCS emulates the physical sensations of active (anodal/cathodal) tDCS but current is only delivered for a short period of time and is not enough to cause any neuromodulations
Sponsors
Wellington Hospital
University of Birmingham
Study design
Allocation
NON_RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Masking description
In the MRI stream all participants will receive anodal, cathodal, and sham (placebo) tDCS sessions in a randomised order. In the Bedside stream participants will receive active tDCS (either anodal or cathodal) and sham sessions also in a randomised order. A researcher not involved in data collection or analyses will programme the stimulator to deliver the specific polarity needed in each session in a double-blind manner. Sham tDCS will be delivered according to published guidelines: this mimics the physical sensations of active stimulation but does not have a neuromodulatory effect
Intervention model description
This is a double-blind randomised crossover feasibility study of tDCS in a small cohort of PDOC individuals. The study is divided into two streams to accommodate differences in the resources available across recruitment sites: 1. MRI stream, which will include MRI and electrophysiology assessments; this is available to patients receiving care at the Wellington Hospital in London only. 2. Bedside stream, which will include electrophysiology assessments only, available to patients in specialist units at NHS (National Health Service) and non-NHS sites
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Aged 18 years or older * Receiving care at a recruitment site, with a consensus clinical diagnosis of PDOC from any aetiology (i.e. traumatic or non-traumatic injury). * Stable and with no need of mechanical support (i.e. respirator, etc.)
Exclusion criteria
* Scalp skin sores or any skin damage at the electrode sites * Metallic implants in the face or skull * Craniectomy or cranioplasty * No evidence of auditory startle in clinical observations, or absent brainstem auditory evoked potentials in recent clinical history (if data available) * MRI incompatible: metal plates incompatible with MRI scanners, pacemaker, inability to lay flat for prolonged periods of time, aneurysm clips, neurostimulators, brain/subdural electrodes, etc. (MRI stream ONLY)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Retention at end of active phase | through completion of active phase of study (tDCS intervention), on average 4 weeks for bedside stream and 8 weeks for MRI stream | percentage of participants on study at pre-specified time points counted from the start of participation in the study (i.e., first study procedure) |
| Retention at 3 months | 3 months after start of participation | percentage of participants on study at pre-specified time points counted from the start of participation in the study (i.e., first study procedure). This Outcome applies to the bedside stream only |
| Retention at 6 months | 6 months after start of participation | percentage of participants on study at pre-specified time points counted from the start of participation in the study (i.e., first study procedure). This Outcome applies to the bedside stream only |
| Completion | through completion of active phase of study (tDCS intervention), on average 4 weeks for bedside stream and 8 weeks for MRI stream | percentage of tDCS, MRI, and electrophysiology assessments completed per polarity |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| EMG (electromyography) amplitude changes | days 1-4 and day 2 of each polarity in the MRI and bedside streams respectively | Changes in the amplitude of the rectified EMG signal (high-pass filtered \> 50Hz) in response to instructions to move |
| Structural MRI | day 1 and day 5 of tDCS each polarity | This will include assessments of the gross macrostructure, and microstructure of brain tissue grey matter, white matter, and cerebrospinal fluid |
| Glasgow Outcome Scale-extended | at 3 and 6 months after start of participation | Scale for functional outcome after brain injury. Total score ranges from 1 to 8, where higher values correspond to better outcome |
| Coma recovery scale -revised | regularly through active phase of study (baseline and outcome assessments), on average 4 weeks for bedside stream and 8 weeks for MRI stream | clinical diagnostic scale for disorders of consciousness. Total score ranges from 0 to 23, where higher scores mean a higher level of functioning and awareness |
| Functional MRI in response to task instructions | day 1 and day 5 of tDCS each polarity | This will include assessments of the BOLD (blood oxygen level-dependent) response to characterise brain activity and connectivity during command following |
| EEG power in the alpha band in response to task instructions | days 1 and 4 of each polarity in the MRI stream and day 1 of each polarity in the bedside stream | Envelope of bandpass filtered EEG data between 8-12 Hertz |
| EEG power in the beta band in response to task instructions | days 1 and 4 of each polarity in the MRI stream and day 1 of each polarity in the bedside stream | Envelope of bandpass filtered EEG data between 13-30 Hertz |
Countries
United Kingdom
Contacts
Primary ContactDavinia Fernandez Espejo, PhD FHEA
Outcome results
None listed