Independent home use of a brain-computer interface by people with amyotrophic lateral sclerosis

Abstract

Objective: To assess the reliability and usefulness of an EEG-based brain-computer interface (BCI) for patients with advanced amyotrophic lateral sclerosis (ALS) who used it independently at home for up to 18 months.

Methods: Of 42 patients consented, 39 (93%) met the study criteria, and 37 (88%) were assessed for use of the Wadsworth BCI. Nine (21%) could not use the BCI. Of the other 28, 27 (men, age 28-79 years) (64%) had the BCI placed in their homes, and they and their caregivers were trained to use it. Use data were collected by Internet. Periodic visits evaluated BCI benefit and burden and quality of life.

Results: Over subsequent months, 12 (29% of the original 42) left the study because of death or rapid disease progression and 6 (14%) left because of decreased interest. Fourteen (33%) completed training and used the BCI independently, mainly for communication. Technical problems were rare. Patient and caregiver ratings indicated that BCI benefit exceeded burden. Quality of life remained stable. Of those not lost to the disease, half completed the study; all but 1 patient kept the BCI for further use.

Conclusion: The Wadsworth BCI home system can function reliably and usefully when operated by patients in their homes. BCIs that support communication are at present most suitable for people who are severely disabled but are otherwise in stable health. Improvements in BCI convenience and performance, including some now underway, should increase the number of people who find them useful and the extent to which they are used.

Figure 1. BCI system and its operation

(A) A home user operating the brain-computer interface (BCI). (B) The EEG amplifier amplifies and digitizes the 8 EEG channels. The laptop computer analyzes the EEG, controls the user screen, and stores all data. (C) BCI operation illustrated with the e-mail application. The 72-item matrix of possible selections (i.e., letters, numbers, functions) is equivalent to a full keyboard. To make a selection, the user pays attention to the desired item as groups of items flash in rapid succession. The e-mail message appears at the top left. A predictive speller option (Word Q3; Mayer-Johnson) is at the bottom left (e.g., after spelling “hel,” the user can complete the word “hello” simply by selecting the numeral 1). (D) BCI detection of the user's selection. (Left) The user's average EEG response at location Pz to the flash of a group of items that includes the desired item (solid red) differs from the average response to the flash of a group that does not include it (dashed green). The BCI detects this difference and selects the desired item. (Right) Topographic distribution (238 milliseconds after flash; nose at top) of the difference between the 2 responses (measured as R²). The EEG recording sites are indicated (Pz is circled). The difference between the responses has a typical posterior-central focus. See elsewhere for details.

Figure 2. Patient progression through the 8 stages of the study

Reasons for attrition at each stage are indicated. ALSFRS-R = ALS Functional Rating Scale–Revised; BCI = brain-computer interface; SA = system assistant.

Figure 3. ALSFRS-R scores and BCI use data

(A) ALS Functional Rating Scale–Revised (ALSFRS-R) scores for each brain-computer interface (BCI) home user (10 with ≥2 scores, 4 with 1 score at study entry). (B) Average duration of BCI use per day vs days used (in percent of days on which the BCI was available for use) for each of the BCI home users. (C) Average breakdown of BCI use time across home users. (Many used the CS/C program far more than needed for the study or for BCI calibration; they appeared to view it as a worthwhile exercise.) (D) Baseline and final average (±SD) ALSFRS-R (circle) and McGill Quality of Life (triangle) scores for the 10 BCI home users with values at ≥2 times. (E) Initial and final average (±SD) BCI benefit (left) and BCI burden (right) scores for the 8 home users (top) and their system assistants (SAs) (bottom) with values at ≥2 times. BKS = audio books; CNV = conversation via WordPad; CS/C = copy-spelling/calibration; EM = e-mail; NWS = Internet news reader; PICS = Pictures; UT = YouTube.