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
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.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
15
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
Moseley Hall Hospital
Birmingham, West Midlands, United Kingdom
The Wellington Hospital
London, United Kingdom
Retention at end of active phase
percentage of participants on study at pre-specified time points counted from the start of participation in the study (i.e., first study procedure)
Time frame: through completion of active phase of study (tDCS intervention), on average 4 weeks for bedside stream and 8 weeks for MRI stream
Retention at 3 months
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
Time frame: 3 months after start of participation
Retention at 6 months
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
Time frame: 6 months after start of participation
Completion
percentage of tDCS, MRI, and electrophysiology assessments completed per polarity
Time frame: through completion of active phase of study (tDCS intervention), on average 4 weeks for bedside stream and 8 weeks for MRI stream
Structural MRI
This will include assessments of the gross macrostructure, and microstructure of brain tissue grey matter, white matter, and cerebrospinal fluid
Time frame: day 1 and day 5 of tDCS each polarity
Functional MRI in response to task instructions
This will include assessments of the BOLD (blood oxygen level-dependent) response to characterise brain activity and connectivity during command following
Time frame: day 1 and day 5 of tDCS each polarity
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EEG power in the alpha band in response to task instructions
Envelope of bandpass filtered EEG data between 8-12 Hertz
Time frame: days 1 and 4 of each polarity in the MRI stream and day 1 of each polarity in the bedside stream
EEG power in the beta band in response to task instructions
Envelope of bandpass filtered EEG data between 13-30 Hertz
Time frame: days 1 and 4 of each polarity in the MRI stream and day 1 of each polarity in the bedside stream
EMG (electromyography) amplitude changes
Changes in the amplitude of the rectified EMG signal (high-pass filtered \> 50Hz) in response to instructions to move
Time frame: days 1-4 and day 2 of each polarity in the MRI and bedside streams respectively
Coma recovery scale -revised
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
Time frame: regularly through active phase of study (baseline and outcome assessments), on average 4 weeks for bedside stream and 8 weeks for MRI stream
Glasgow Outcome Scale-extended
Scale for functional outcome after brain injury. Total score ranges from 1 to 8, where higher values correspond to better outcome
Time frame: at 3 and 6 months after start of participation