Clinical feasibility of brain‐computer interface based on steady‐state visual evoked potential in patients with locked‐in syndrome: Case studies

Abstract

Although the feasibility of brain-computer interface (BCI) systems based on steady-state visual evoked potential (SSVEP) has been extensively investigated, only a few studies have evaluated its clinical feasibility in patients with locked-in syndrome (LIS), who are the main targets of BCI technology. The main objective of this case report was to share our experiences of SSVEP-based BCI experiments involving five patients with LIS, thereby providing researchers with useful information that can potentially help them to design BCI experiments for patients with LIS. In our experiments, a four-class online SSVEP-based BCI system was implemented and applied to four of five patients repeatedly on multiple days to investigate its test-retest reliability. In the last experiments with two of the four patients, the practical usability of our BCI system was tested using a questionnaire survey. All five patients showed clear and distinct SSVEP responses at all four fundamental stimulation frequencies (6, 6.66, 7.5, 10 Hz), and responses at harmonic frequencies were also observed in three patients. Mean classification accuracy was 76.99% (chance level = 25%). The test-retest reliability experiments demonstrated stable performance of our BCI system over different days even when the initial experimental settings (e.g., electrode configuration, fixation time, visual angle) used in the first experiment were used without significant modifications. Our results suggest that SSVEP-based BCI paradigms might be successfully used to implement clinically feasible BCI systems for severely paralyzed patients.

An emergency call system for patients in locked‐in state using an SSVEP‐based brain switch

“…Additionally, because patients in an LIS are generally bedridden and require mechanical ventilation through a tracheostomy, the experimenters should pay particular attention while they are attaching the electrodes to patients' occipital areas. We used a doughnut/ring‐shaped cushion to secure space between the electrodes and the bed (Hwang et al, ).…”

“…Additionally, because patients in an LIS are generally bedridden and require mechanical ventilation through a tracheostomy, the experimenters should pay particular attention while they are attaching the electrodes to patients' occipital areas. We used a doughnut/ring-shaped cushion to secure space between the electrodes and the bed (Hwang et al, 2016). Clinical feasibility of SSVEP-based BCI systems has been seamlessly questioned since early 2000s (Wolpaw et al, 2002) because the development of camera-based eye trackers can provide very sensitive and accurate estimations of gaze directions (Cecotti, 2016;Kim, Kim, & Jo, 2015;Pasqualotto et al, 2015).…”

A systematic review of hybrid brain-computer interfaces: Taxonomy and usability perspectives

“…Sixteen studies recruited participants with disabilities [55,65,66,76,143–145,148–156]. The most common type of disability was sclerosis [52,55,65,66,76,143–145,149–151,153–155]. Among them, two articles recruited multiple sclerosis patients, and nine articles recruited amyotrophic lateral sclerosis patients.…”

“…Among the seven studies of movement control tasks, only three studies did not use any subjective measures for usability evaluation of BCI [62,66,155]. In addition, Modified QUEST 2.0, SUS survey, and modified SUS surveys were used in the closed copying task and ATD PA device form was only used in closed self-managing tasks and QUEST 2.0 was only used in open tasks.…”

“…Among nine studies using selection control tasks, seven studies used subjective measures, and one study proposed new measures in the closed copying task [149]. Only two studies did not use subjective measures in the selection control task experiments [64,155]. In the cognitive rehabilitation and brain painting tasks, all studies used subjective measures.…”