A visual brain-computer interface as communication aid for patients with amyotrophic lateral sclerosis

OBJECTIVE: Brain-Computer Interface (BCI) spellers that make use of code-modulated Visual Evoked Potentials (cVEP) may provide a fast and more accurate alternative to existing visual BCI spellers for patients with Amyotrophic Lateral Sclerosis (ALS). However, so far the cVEP speller has only been tested on healthy participants. METHODS: We assess the brain responses, BCI performance and user experience of the cVEP speller in 20 healthy participants and 10 ALS patients. All participants performed a cued and free spelling task, and a free selection of Yes/No answers. RESULTS: 27 out of 30 participants could perform the cued spelling task with an average accuracy of 79% for ALS patients, 88% for healthy older participants and 94% for healthy young participants. All 30 participants could answer Yes/No questions freely, with an average accuracy of around 90%. CONCLUSIONS: With ALS patients typing on average 10 characters per minute, the cVEP speller presented in this paper outperforms other visual BCI spellers. SIGNIFICANCE: These results support a general usability of cVEP signals for ALS patients, which may extend far beyond the tested speller to control e.g. an alarm, automatic door, or TV within a smart home

Is the Frontal Assessment Battery reliable in ALS patients?

<p>The assessment of frontal functions in ALS patients is important because of the overlap with the behavioural variant of frontotemporal dementia (bvFTD). We investigated the applicability and reliability of the Frontal Assessment Battery (FAB) within a cohort of predominantly prevalent ALS patients. The FAB was administered to 85 ALS patients and eight ALS-bvFTD patients. Original scores and the percentage of items that could be performed were recorded. Item-adjusted scores of the FAB were calculated. The ALS Functional Rating Scale-Revised version (ALSFRS-R) was used to assess disease severity. Eighty-seven patients (94%) had ALS symptoms of more than one year. Twenty patients (21.5%) were not able to perform one or more FAB items. The original FAB score correlated with the ALSFRS-R score (r = 0.30; p <0.01), while the item-adjusted FAB score did not. In contrast to the original FAB scores, the item-adjusted FAB score was lower in ALS-bvFTD patients (66.7, range 33.3-100) compared to ALS patients without bvFTD (94.4, range 38.9-100; p <0.01). In summary, 20% of prevalent ALS patients could not complete the FAB, which limits its use in ALS and emphasizes the importance of disease specific instruments and adjusting for motor impairment in cognitive and behavioural examinations of ALS patients.</p>