Command following assessment and communication with vibro-tactile P300 and motor imagery BCIs in patients with disorders of consciousness and locked-in syndrome.
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1
Guger Technologies (Austria), Austria
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2
Università degli Studi di Palermo, ALS Clinical Research Center, BioNeC, Italy
Many patients with disorders of consciousness (DOC), locked-in syndrome (LIS) or complete locked-in syndrome (CLIS) also need brain-computer interface (BCI) platforms that do not rely on visual stimuli and are easy to use [1]. DOC patients are in the unresponsive wakefulness state (UWS) or minimal consciousness state (MCS).
We investigate command following and communication functions using BCI paradigms with 9 LIS, 3 CLIS, 13 UWS patients and three healthy controls. These tests were done with vibro-tactile stimulation with 2 or 3 stimulators (VT2 and VT3 mode) and with motor imagery (MI) paradigms. In VT2 the stimulators are fixed on the left and right wrist and the participant has the task to count the stimuli on the target hand in order to elicit a P300 response. In VT3 mode an additional stimulator is placed as a distractor on the shoulder and the participant is counting stimuli either on the right or left hand. In motor imagery mode the participant is instructed to imagine left or right hand movement. VT3 and MI also allow the participant to answer yes and no questions.
Healthy controls achieved a mean assessment accuracy of 94% in VT2, 88% in VT3, and 73% in MI modes. They were able to communicate with VT3 (86.7%) and MI (83.3%) after 2 training runs. The LIS/CLIS patients achieved a mean accuracy of 76.6% in VT2, 63.1% in VT3, and 58.2% in MI modes after 1-2 training runs. 9 out of 12 LIS patients could communicate by using the vibro-tactile P300 paradigms (answered on average 8 out of 10 questions correctly) and 3 out of 12 could communicate with the motor imagery paradigm (answered correctly 4,7 out of 5 questions). 2 out of the 3 CLIS patients could use the system to communicate with VT3 (90 and 70% accuracy). The UWS patients achieved a mean accuracy of 53.8% in VT2 and 31.2% in VT3. MI was not tested in these UWS patients. 3 out of 13 UWS patients could establish communication with the VT3 paradigm and achieved a mean accuracy of 75% within 1-4 training runs. Table I further subdivides these results into UWS patients that communicated and UWS patients that did not communicate and a clear difference in VT2 and VT3 accuracies can be noted.
Table I. BCI assessment accuracy and communication accuracy for different patients and healthy controls.
Table I also shows that best results are obviously achieved with healthy controls. Interestingly LIS and CLIS patients that communicated show almost the same results as healthy controls. LIS and CLIS patients are clearly worse, but better than UWS patients that could not communicate.
The results show that paradigms based on non-visual evoked potentials can be effective for these users. MI paradigms are effective for less users than the VT2 and VT3 ones.
The study is important because it showed that a majority of LIS patients can use a BCI system for communication and it also proved that it is effective in CLIS and UWS patients. Further testing is of course necessary to study stability and long-term effects.
Acknowledgements
The research was funded by H2020 project ComAware.
References
Reference
Guger, C., Spataro, R., Allison, B. Z., Heilinger, A., Ortner, R., Cho, W., & La Bella, V. (2017). Complete Locked-in and Locked-in patients: Command following assessment and communication with vibro-tactile P300 and motor imagery brain-computer interface tools. Frontiers in Neuroscience, 11, 251.
Keywords:
brain-computer interface (BCI),
locked-in syndrom,
disorders of consciousness,
EEG/ERP,
P300 event-related potential
Conference:
2nd International Neuroergonomics Conference, Philadelphia, PA, United States, 27 Jun - 29 Jun, 2018.
Presentation Type:
Oral Presentation
Topic:
Neuroergonomics
Citation:
Guger
C,
Spataro
R and
Edlinger
G
(2019). Command following assessment and communication with vibro-tactile P300 and motor imagery BCIs in patients with disorders of consciousness and locked-in syndrome..
Conference Abstract:
2nd International Neuroergonomics Conference.
doi: 10.3389/conf.fnhum.2018.227.00048
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Received:
20 Mar 2018;
Published Online:
27 Sep 2019.
*
Correspondence:
Dr. Christoph Guger, Guger Technologies (Austria), Graz, 8020, Austria, guger@gtec.at