EEG reactivity changes captured via mobile BCI device following tDCS intervention – a pilot-study in disorders of consciousness (DOC) patients

Open-label transcranial direct current stimulation (tDCS) treatment in six patients with disorders of consciousness (DOC) was examined, focusing on the possible clinical benefits and changes in event-related EEG reactivity immediately following a 10 days anodal left-prefrontal cortex tDCS treatment versus pre-treatment clinical and neural reactivity parameters, as well as noting clinical recovery parameters over a post-treatment period of one year. Anodal tDCS over the left PFC has been shown to improve levels of awareness in minimally conscious state patients (MCS) patients. MCS patients may display short transient episodes of reactivity to specific verbal stimuli versus other totally unresponsive awake DOC subgroups that seem to be in a vegetative state (VS). Patients EEG were collected via two main EEG systems, the Neurosteer® system, a mobile 3-electrode neurological BCI allowing cloud-based online analysis of the classical EEG bands, along with novel machine-learning based biomarkers, and a standard clinical EEG/ERP 19 channel wired-system, that includes an offline integrated-software to execute Time-frequency analyses and ERP analyses of different brain states (qEEG) and evaluate evoked sensory/cognitive processing potential-components captured in event-related potentials (ERP's) reflecting early auditory information processing. Clinical recovery scores, noting reactivity to stimuli and levels of awareness were noted at baseline (paired with mobile 3-channel Neurosteer-system biomarker activity recording) and after the tDCS intervention, as well as during the one-year post-stimulation period. Preliminary results indicate changes in clinical recovery scores, auditory ERP's indicating increased sensitivity to echoic memory neural-excitability, and in the EEG-based biomarkers in a subset of patients (three patients). One patient that showed the most pronounced clinical improvement following tDCS treatment indicated significant change in his auditory ERP's, VC9 biomarker and frontal theta activity, while the other patients that showed significant changes in their event-related brain activity did not reveal changes in their clinical recovery scores. These findings may imply higher sensitivity of pre-attentive auditory ERPs and EEG-based machine-learning event-related parameters versus the standard clinical testing scores used to detect DOC patients’ condition in the clinical setting. Importantly, unlike the standard clinical EEG systems that acquire ERP's, the Neurosteer® system can be applied during routine examinations of CRS-R scores at bedside, without additional experimental sessions, can be viewed online, without trained personnel, and avoiding time-consuming EEG application or offline EEG analyses.