Performance Differences Using a Vibro-Tactile P300 BCI in LIS-Patients Diagnosed With Stroke and ALS

Abstract

Patients with locked-in syndrome (LIS) are typically unable to move or communicate and can be misdiagnosed as patients with disorders of consciousness (DOC). Behavioral assessment scales are limited in their ability to detect signs of consciousness in this population. Recent research has shown that brain-computer interface (BCI) technology could supplement behavioral scales and allows to establish communication with these severely disabled patients. In this study, we compared the vibro-tactile P300 based BCI performance in two groups of patients with LIS of different etiologies: stroke (n = 6) and amyotrophic lateral sclerosis (ALS) (n = 9). Two vibro-tactile paradigms were administered to the patients to assess conscious function and command following. The first paradigm is called vibrotactile evoked potentials (EPs) with two tactors (VT2), where two stimulators were placed on the patient’s left and right wrist, respectively. The patients were asked to count the rare stimuli presented to one wrist to elicit a P300 complex to target stimuli only. In the second paradigm, namely vibrotactile EPs with three tactors (VT3), two stimulators were placed on the wrists as done in VT2, and one additional stimulator was placed on his/her back. The task was to count the rare stimuli presented to one wrist, to elicit the event-related potentials (ERPs). The VT3 paradigm could also be used for communication. For this purpose, the patient had to count the stimuli presented to the left hand to answer “yes” and to count the stimuli presented to the right hand to answer “no.” All patients except one performed above chance level in at least one run in the VT2 paradigm. In the VT3 paradigm, all 6 stroke patients and 8/9 ALS patients showed at least one run above chance. Overall, patients achieved higher accuracies in VT2 than VT3. LIS patients due to ALS exhibited higher accuracies that LIS patients due to stroke, in both the VT2 and VT3 paradigms. These initial data suggest that controlling this type of BCI requires specific cognitive abilities that may be impaired in certain sub-groups of severely motor-impaired patients. Future studies on a larger cohort of patients are needed to better identify and understand the underlying cortical mechanisms of these differences.

Successful BCI communication via high-frequency SSVEP or visual, audio or tactile P300 in 30 tested volunteers

“…This confirmed the applicability of the tested system in clinical settings. Our result is also in line with other studies (Lule et al, 2013;Lugo et al, 2014;Sellers el al., 2014;Annen et al, 2018, Heilinger et. al., 2018, that showed the capacity for using BCI after severe brain injury with high accuracy for at least one patient in respective experimental groups.…”

“…For the first group, BCI provides a chance for communication and rehabilitation (Beukelman et al, 2011), and for the latter group this technology could improve diagnosis and allow for establishing communication (Luauté et al, 2015). Recently, several studies of BCI performance in neurological patients showed promising results (Lule et al, 2013;Lugo et al, 2014;Sellers el al., 2014;Annen et al, 2018;Heilinger et. al., 2018).…”

Brain‐computer interfaces for amyotrophic lateral sclerosis

“…They found reduced accuracy for the auditory system when compared with the visual system. Heilinger et al found that ALS patients could use a P300 system based on vibrotactile stimuli.…”

Towards electroencephalography-based consciousness assessment and cognitive function profiling in prolonged disorders of consciousness

“…LIS is not a disorder of consciousness; it is a condition in which patients are wholly aware but struggle to produce overt motor responses due to paralysis and anarthria. LIS patients primarily communicate using eye movements or by blinking; a process which is not possible for completely locked-in syndrome (CLIS) patients as they also have oculomotor impairment 17,18 . A survey of forty-four LIS patients in France by León-Carrión et al (2002) found that it took an average of 78.1 days for a patient to be diagnosed with LIS 16 .…”