Awareness Detection and Communication in Disorders of Consciousness

Condition(s) studied

Investigational drug(s) / intervention(s)

Motor imagery based EEG-BCI: Information gathered in this study may be useful when considering diagnosis of prolonged disorder of consciousness and successful adoption of device could lead to assistive communication intervention with therapeutic benefits. Participants undergo quick assessment to test ability to engage in task, if successful this implies they are minimally conscious, have some awareness of self and memory intact to remember commands. During training participant undergoes multiple sessions whereby they are conducting two different imagined movements to move a sound across the azimuthal plane in a direction dictated by an auditory cue. Participant will receive auditory feedback on the position of the sound which acts as a reflection of how well the participant is engaged in the task in terms of performance and consistency across trials. The participant will move on to use the imagined movements to answer a series of biographical, situational, basic logic and numbers/letters questions.

Study summary

STUDY OVERVIEW Brain injury can result in a loss of consciousness or awareness, to varying degrees. Some injuries are mild and cause relatively minor changes in consciousness. However, in severe cases a person can be left in a state where they are "awake" but unaware, which is called unresponsive wakefulness syndrome (UWS, previously known as a vegetative state). Up to 43% of patients with a UWS diagnosis, regain some conscious awareness, and are then reclassified as minimally conscious after further assessment by clinical experts. Many of those in the minimally conscious state (MCS) and all with unresponsive wakefulness syndrome (UWS) are incapable of providing any, or consistent, overt motor responses and therefore, in some cases, existing measures of consciousness are not able to provide an accurate assessment. Furthermore, patients with locked-in syndrome (LIS), which is not a disorder of consciousness as patients are wholly aware, also, struggle to produce overt motor responses due to paralysis and anarthria, leading to long delays in accurate diagnoses using current measures to determine levels of consciousness and awareness. There is evidence that LIS patients, and a subset of patients with prolonged disorders of consciousness (DoC), can imagine movement (such as imagining lifting a heavy weight with their right arm) when given instructions presented either auditorily or visually - and the pattern of brain activity that they produce when imagining these movements, can be recorded using a method known as electroencephalography (or EEG). With these findings, the investigators have gathered evidence that EEG-based bedside detection of conscious awareness is possible using Brain- Computer Interface (BCI) technology - whereby a computer programme translates information from the users EEG-recorded patterns of activity, to computer commands that allow the user to interact via a user interface. The BCI system for the current study employs three possible imagined movement combinations for a two-class movement classification; left- vs right-arm, right-arm vs feet, and left-arm vs feet. Participants are trained, using real-time feedback on their performance, to use one of these combinations of imagined movement to respond to 'yes' or 'no' answer questions in the Q\&A sessions, by imagining one movement for 'yes' and the other for 'no'. A single combination of movements is chosen for each participant at the outset, and this participant-specific combination is used throughout their sessions. The study comprises three phases. The assessment Phase I (sessions 1-2) is to determine if the patient can imagine movements and produce detectable modulation in sensorimotor rhythms and thus is responding to instructions. Phase II (sessions 3-6) involves motor-imagery (MI) -BCI training with neurofeedback to facilitate learning of brain activity modulation; Phase III (sessions 7-10) assesses patients' MI-BCI response to closed questions, categorized to assess biographical, numerical, logical, and situational awareness. The present study augments the evidence of the efficacy for EEG-based BCI technology as an objective movement-independent diagnostic tool for the assessment of, and distinction between, PDoC and LIS patients.

Eligibility

Primary outcome measure(s)

• Change in performance accuracy of BCI use pre- and post- training — ~10 sessions of ~1.5 hours
  The main primary outcome measure is BCI performance (e.g., accuracy in % for repeated binary choice selections using the BCI e.g., movement free control of cursor towards one of two targets using EEG-based BCI or accuracy in discriminating different brain responses associated with imagined movement of different limbs. Multiple cross validation will be performed to assess the significance of the difference between a baseline accuracy (pre cue- where accuracy in the response is expected to be around 50% (chance level)) and the peak accuracy (where the accuracy of discriminating event related brain response peaks following the cue).
• Change in ability to use imagined movements to consistently communicate yes-no responses to closed questions over multiple sessions by participant with Prolonged Disorder of Consciousness — 3-4 sessions of ~1.5 hours
  Accuracy rate when using the BCI system to provide known responses to statements will be used to build evidence to establish that participants could use the technology as an aided communication method. Examples of questions are given below. Yes Questions: Your name is David. You are 25 years old.

Trial sites (18)

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