Brain-computer interface (BCI) evaluation in people with amyotrophic lateral sclerosis

Abstract

Brain-computer interfaces (BCIs) might restore communication to people severely disabled by amyotrophic lateral sclerosis (ALS) or other disorders. We sought to: 1) define a protocol for determining whether a person with ALS can use a visual P300-based BCI; 2) determine what proportion of this population can use the BCI; and 3) identify factors affecting BCI performance. Twenty-five individuals with ALS completed an evaluation protocol using a standard 6 × 6 matrix and parameters selected by stepwise linear discrimination. With an 8-channel EEG montage, the subjects fell into two groups in BCI accuracy (chance accuracy 3%). Seventeen averaged 92 (± 3)% (range 71–100%), which is adequate for communication (G70 group). Eight averaged 12 (± 6)% (range 0–36%), inadequate for communication (L40 subject group). Performance did not correlate with disability: 11/17 (65%) of G70 subjects were severely disabled (i.e. ALSFRS-R < 5). All L40 subjects had visual impairments (e.g. nystagmus, diplopia, ptosis). P300 was larger and more anterior in G70 subjects. A 16-channel montage did not significantly improve accuracy. In conclusion, most people severely disabled by ALS could use a visual P300-based BCI for communication. In those who could not, visual impairment was the principal obstacle. For these individuals, auditory P300-based BCIs might be effective.

Key words::

• Amyotrophic lateral sclerosis (ALS)
• brain-computer interface (BCI)
• augmentative and alternative communication (AAC)
• event-related potentials (ERP)
• rehabilitation
• P300

Acknowledgments

We are extremely grateful to the subjects and their caregivers for their time and effort. We also thank Laura Tenteromano and Rafi Kupferman of Helen Hayes Hospital for their contributions.

Declaration of interest: At the time of data collection, data analysis, and manuscript preparation, none of the authors had any relationship that could potentially bias the results presented here. The authors alone are responsible for the content and writing of the paper.

Funding was provided by the NIH, NIBIB & NINDS and the James S. McDonnell, Altran, ALS Hope, and NEC Foundations. None had any role in this study or in this article.