Communication in locked-in state after brainstem stroke: a brain-computer-interface approach.

In a recent study by Sellers et al. (1) a patient in locked-in state after brainstem stroke was able to successfully communicate via electroencephalography (EEG) based brain computer interface (BCI) employing a P300 speller paradigm. BCI uses the brain signal, which can either be the electrical signal (electroencephalography-EEG) (2) or a change in hemodynamic activity [functional magnetic resonance imaging-fMRI (3,4); near infrared spectroscopy-NIRS (5)], to enable patients lacking control of their muscles in communication and controlling external mechanical devices. BCIs using EEG exist since 1970's (6) and several researchers have developed BCI using different features of EEG, namely slow cortical potential (SCP) based BCI (7,8), sensorimotor rhythm (SMR) based BCI (9,10) and P300 based BCI (11,12). The scientific literature is full of BCI studies done on healthy human participants where the participants' moved an object on the computer screen (9), wrote a sentence (8) and moved a robotic arm (13) among several other tasks. Limited studies have been performed on patient populations where the BCI can improve lost functions of individuals with disabilities. In that light it is very exciting whenever a BCI study is performed on an individual who is in dire need of such a technology. In our laboratory SCP-BCI (7,8,14), SMR-BCI (10,14) and P300 BCI (14) have been used extensively since 1999 to help ALS patients in locked-in state in communication. To date very limited research has been done on the application of BCI for communication in patients in locked-in state (LIS) after brainstem stroke. In the scientific literature there are two different studies describing the application of BCI in patient in LIS after brainstem stroke (15,16). In one of the study the patient in LIS after brainstem stroke was trained to control her SCP but the study could not be carried on further as the patient regained some muscular control to some extent (15). In the other study P300 based BCI was used to train a patient in LIS after brainstem stoke, to move a ball on the screen towards a specified target (16). To date no study has been published prior to Sellers et al. (1) were BCI was used for communication in a patient in LIS after brainstem stroke. In the recent study (1) a P300 speller based BCI was used for communication in a 68 year old male who suffered a multifocal acute ischemic infarction and had little control over eye blinking. If …