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Brain-Computer Interfaces for communication: preferences of
individuals with locked-in syndrome
Mariana P Branco1,#, Elmar GM Pels, MSc, PhD1,#, Ruben H Sars, MSc1,2, Erik J Aarnoutse,
PhD1, Nick F Ramsey, PhD1,+, Mariska J Vansteensel, PhD1, Femke Nijboer, PhD2,3
1UMC Utrecht Brain Center, Department of Neurology and Neurosurgery, University Medical
Center Utrecht, Utrecht, The Netherlands 2Health, Medical and Neuropsychology Unit, Faculty of
Social and Behavioral Sciences, Leiden University, Leiden, The Netherlands 3Biomedical Signals
and Systems Department, Faculty of Electrical Engineering, Mathematics and Computer Science,
University of Twente, Enschede, The Netherlands
Abstract
Background—Brain-Computer Interfaces have been proposed as an assistive technology (AT)
allowing people with locked-in syndrome (LIS) to use neural signals to communicate. To design a
communication BCI (cBCI) that is fully accepted by the users, their opinion should be taken into
consideration during the research and development process.
Objective—We assessed the preferences of prospective cBCI users regarding 1) the applications
they would like to control with a cBCI, 2) the mental strategies they would prefer to use to control
the cBCI and 3) when during their clinical trajectory they would like to be informed about AT and
cBCIs. Furthermore, we investigated if individuals diagnosed with progressive and sudden onset
disorders differ in their opinion.
Methods—We interviewed 28 Dutch individuals with LIS during a 3-hour home visit using
multiple choice, ranking and open questions. During the interview participants were informed
about BCIs and the possible mental strategies.
Results—Participants rated (in)direct forms of communication, computer use and environmental
control as the most desired cBCI applications. In addition, active cBCI control strategies were
preferred over reactive strategies. Furthermore, individuals with progressive and sudden onset
disorders preferred to be informed about AT and cBCIs at the moment they would need it.
Conclusions—We show that individuals diagnosed with progressive and sudden onset disorders
preferred in general the same applications, mental strategies and time of information. By
+Corresponding author: Nick F Ramsey, UMC Utrecht Brain Center, Department of Neurology and Neurosurgery, University
Medical Center Utrecht, P.O. Box 85500, 3508 GA, Utrecht, The Netherlands. N.F.Ramsey@umcutrecht.nl.
#These authors contributed equally to this article
Data Availability
Animation videos used in this questionnaire (Video 1 – Video 9; in English) are available at https://doi.org/10.5281/zenodo.3271440.
Questionnaire (Dutch only) and data can be made available upon reasonable request to the authors and after signing a data transfer
agreement.
HHS Public Access
Author manuscript
Neurorehabil Neural Repair
. Author manuscript; available in PMC 2021 March 12.
Published in final edited form as:
Neurorehabil Neural Repair
. 2021 March ; 35(3): 267–279. doi:10.1177/1545968321989331.
Author Manuscript Author Manuscript Author Manuscript Author Manuscript
collecting the opinion of a large sample of individuals with LIS, this study provides valuable
information to stakeholders in cBCI and other AT development.
Keywords
Brain-Computer Interface; Communication; opinion; user-centered design; locked-in syndrome
1. Introduction
Stroke, trauma or neuromuscular diseases, such as Amyotrophic Lateral Sclerosis (ALS), are
merely a few examples of the causes that can lead to complete loss of voluntary muscle
control and subsequent loss of communication. When people have no means to
communicate other than eye movements, they are considered to be in a locked-in state
(locked-in syndrome; LIS) 1. LIS is characterized by aphonia or severe hypophonia,
preserved cognition and quadriplegia or quadriparesis and affects about 0.8 out of 100 000
people in Western Europe 2,3. Contrarily to what is generally expected, individuals with LIS
report a satisfactory quality-of-life, which mostly depends on their ability to communicate
and to be autonomous 4–6.
In the last decades, several communication BCIs (or cBCIs) have been developed as
alternative assistive technology (AT) and have been evaluated with individuals with LIS 7–12.
In order to develop functional and widely accepted cBCI technology, the user’s opinion and
participation throughout the research and development phases of the AT (User-Centered
Design, UCD) is crucial 13. For that reason, UCD has received increasing attention in the
BCI field with the goal to manage BCI users’ expectations and to prevent the abandonment
of technology by the end-user 7,14–23. These studies focused not only on the technical
specifications of the BCI system, such as the technique used for recording brain-signals
(internal or external electrodes; e.g., 24), general BCI applications (what a user would like to
control with a BCI and how well it should work; e.g., 15,20), but also on the subjective
acceptance of the technology 17,21. Although the opinion of prospective users about BCI
applications (beyond communication) has been investigated before 15,20, to our knowledge
no information has been collected about the user’s opinions on different mental strategies for
cBCI control, nor on when in the course of their medical condition users would like to be
informed about AT and cBCIs. The latter, especially when the user needs change due to
progression of the disease, may also affect the acceptance of AT.
In this study we investigated the opinion of prospective cBCI users in the Netherlands
regarding 1) which applications they would like to control with a cBCI, 2) which mental
strategies they would prefer to use to control the cBCI and 3) the time point during their
clinical trajectory at which they would like to be informed about ATs, including cBCIs.
Importantly, the nature of the underlying medical conditions (that is, progressive disease vs
stable condition after an event) may affect the preference of the user with respect to these
three research questions. Therefore, we compared participants with respect to the type of
condition underlying LIS, that is, neuromuscular disease (NMD) or sudden onset events
(SO). A better understanding of these preferences is fundamental for an efficient and
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effective development of cBCIs and for increasing the likelihood of adoption of this
technology for autonomous home-use.
2. Material and Methods
A questionnaire was administered to individuals with LIS who were making use of AT for
communication and who could potentially benefit from cBCIs. The questionnaire (in Dutch)
was completed by the participant during a 3-hour home visit with two researchers. One
researcher interviewed the participant, while the other researcher made observations and
confirmed the answers from the participants. The questionnaire was implemented on the
Qualtrics Survey platform (www.qualtrics.com/). The study was evaluated by the local ethics
board of the Utrecht Medical University Center, who determined it to be exempt from the
Medical Scientific Research Act. In accordance with the local ethics guidelines, GCP and
the GDPR, at the beginning of the home visit, participants or (when a participant was unable
to write) caregivers on behalf of the participant gave written informed consent to participate
in the study.
2.1 Participants
Forty participants living in the Netherlands were identified using databases obtained in
earlier studies and were invited to participate in this study 2,19. Candidates were approached
through email and received an information letter about the research. When interested in
participating in the study, the candidates were sent an online screening form, which was used
for participant characterization and demographics (see section 2.2.1). Inclusion criteria in
the study were: 1) (in)complete LIS, defined as in 1; 2) the ability to indicate yes and no
reliably, and to thereby give informed consent to participate in the study; and 3) the ability to
answer open questions, either with the help of a letter card or through an AT device. Eligible
candidates were subsequently contacted by a researcher to plan a 3-hour home-visit. In total,
29 participants enrolled in the study (73% response rate; BQ1-BQ29). One participant
(BQ4) was excluded from further analysis after the home-visit because of unreliable means
of communication, yielding 28 complete interviews (Supplementary Table 1). Of these, two
participants were at the time of the interview implanted with a cBCI 10,25.
The revised Amyotrophic Lateral Sclerosis Functional Rating Scale score (ALSFRS-r; 26)
was used to assess the level of paralysis and communication impairment of each participant.
Responses to each item of the ALSFRS-r were described by the participant and caregiver
and scored by both researchers independently. For comparison purposes, the participant
population was divided by type of disorder into one group with neuromuscular disorder
(NMD; such as amyotrophic lateral sclerosis, primary lateral sclerosis and – progressive –
spinal muscular atrophy) and one group with sudden onset (SO; such trauma or stroke).
There were in total 13 NMD and 15 SO participants.
2.2 Structure of the questionnaire
The questionnaire consisted of five sections: 1) demographics, 2) introduction to cBCIs, 3)
cBCI applications, 4) mental strategies and 5) time of information. Animation videos were
used to illustrate certain aspects of the questionnaire, more specifically to introduce the
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concept of cBCIs (Figure 1A) and each individual mental strategy (Figure 1B). The
animations were specifically designed for the purpose of this questionnaire and were
narrated in Dutch (see 27). The majority of the questions were either multiple-choice or
based on a 5-point Likert scale. Participants always had the opportunity to make remarks or
to skip a question. Family members/caregivers were often present during the interview, but
were asked not to answer questions on behalf of the participant. Each question and answer
option was read out aloud by the researcher. When an animation video was part of the
question, the question and answers were read first, after which the video was shown, and
then the question and answers were repeated. The answers were only registered once the
participant clearly understood the question and the answer options. Lastly, at the end of the
questionnaire, we asked the participants to rate their willingness to consider a cBCI for
communication using a 5-point Likert scale (1 = very unlikely, 5 = very likely). Ranking
questions, applications and mental strategies were randomly presented to prevent an order
effect.
2.2.1 Section 1 (Demographics)—Prior to the home visit, participants were asked to
fill out an online questionnaire on their demographic information. Questions were either
multiple-choice, yes/no or required a brief open answer. When applicable, more than one
choice could be selected and an item ‘Other’ was available (followed by a free-text field) in
order to accommodate other options.
2.2.2 Section 2 (Introduction)—An animation video (see Figure 1A for examples of
snapshots) was used to introduce the concept of BCIs in general and in particular BCIs for
communication (cBCIs). In this video we described the concept of an ideal cBCI that would
be 100% accurate and 100% accepted by the users, and we did not provide details about the
different signal acquisition, processing and classification methods. This choice allowed
participants to focus on the choice of applications and mental strategies rather than factors as
efficacy, speed or level of invasiveness.
2.2.3 Section 3 (cBCI applications)—In this section we asked questions about the AT
aids the participants used at the time of the visit at home for communication, what
applications they controlled with it and how often they used that functionality. Additionally,
we asked them to rank their preference with respect to 6 different cBCI applications:
private
conversation and writing
(e.g., email, chat, diary),
direct personal communication
(e.g.,
voice synthesis, direct conversation),
environmental control
(e.g., home appliances, alarm),
general computer use
(e.g., playing games, internet surfing, social media),
artistic expression
(e.g., painting, making music) and
emotions and facial expressions
(e.g., expressing feelings,
emoji’s). In this questionnaire we asked participants about their current AT applications and
did not ask about which applications they would like to be offered by a cBCI as the answer
would likely be ‘all applications’. However, we did ask the participants to rank the
application to be provided by a cBCI in order of preference.
2.2.4 Section 4 (Mental strategies)—We assessed the opinion of the participants
regarding 8 widely known mental strategies that can be used to generate brain signal
changes for cBCI 28–32, namely,
attempted hand movement, attempted body movement
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(other than hand),
attempted speech, counting backwards, visual imagery, visual P300,
auditory P300
and
steady-state visual evoked potentials (SSVEPs)
(Figure 1C). Each
strategy was presented (in random order) using a dedicated animation video (see Figure 1B
for examples of snapshots). Of note, in order to keep the explanation of all strategies
consistent, all were illustrated using the same output control: a one-dimensional control of a
button press that selects a letter on a spelling device (Figure 1B), thereby aiming to focus on
the concept behind the mental strategy and not the type, speed or accuracy of the system.
Participants were asked to imagine using a perfectly working cBCI. After each animation the
participant was asked to imagine using that particular strategy for about 10 seconds and then
rate it (using a 5-point Likert scale) on clarity, difficulty and enjoyability (i.e., how much fun
it was to perform the strategy) and lastly rank all strategies in order of preference.
2.2.5 Section 5 (Time of information)—In the last section of the questionnaire, we
asked the participants’ opinion about the best period to be informed about AT-aids in
general, including cBCIs. The participants could indicate at what time point during their
clinical trajectory they would prefer to have received detailed information about
communication aids. Answer options were: ‘as soon as possible’ after diagnosis/incident,
‘before rehabilitation’ (possible period between incident/hospitalization and start of for
example speech-language therapy, ergotherapy or other), ‘during rehabilitation’, ‘after
rehabilitation’, ‘when no residual movement/speech is available’ or an open field for another
timepoint.
2.3 Data analysis
2.3.1 Descriptive statistics and open answers—Descriptive statistics were used to
analyze the survey results. Frequencies, percentages or medians were used when
appropriate. The percentages were computed relative to the total number of participants (i.e.,
N=28) or, when applicable, to a subgroup of participants.
2.3.2 Ranking questions—To quantify the preference of the participants for specific
applications and mental strategies (ranking questions), we attributed a weight to each option
between 0 and 6 for the applications and between 0 and 4 for the mental strategies, where 0
represented ‘not chosen’, 1 ‘the least preferred’ and 4 or 6 ‘the most preferred’. The
different maximum weights related to the number of items ranked. Notably, the participants
ranked all 6 applications, as it can be assumed that all applications are (eventually) useful for
the user. In contrast, users typically only need one or a few mental strategies to control a
cBCI, and were therefore asked to rank the top 4 (out of 8) mental strategies. Subsequently,
we computed the center-of-mass score (COM) previously used in questionnaire analysis 33
in order to combine ranking scores across participants and to facilitate comparison between
options. The COM was computed per application or mental strategy by summing the product
of the number of subjects who assigned a certain rank to an application/mental strategy and
the weight given to that rank, and subsequently dividing this sum by the total number of
participants:
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COMi=∑k= 1
Nk· ∑s= 1
T[weights=k]
T(1)
where
i
represents an application or a mental strategy,
T
the total number of participants
(indexed by
s
),
k
the weight between 1 and
N
(i.e., the total number of ranked applications,
N
=6, or mental strategies,
N
=4), and [weights = k] is 1 if weights is equal to k and 0
otherwise. The COM score varied between 0 and the total number of ranked options (4 or 6),
and a larger COM value indicates a more preferred option. Statistical comparison between
COM scores is not possible as there is only one value per class. Nevertheless, meaningful
differences of COM values between applications and mental strategies were computed by
applying a Monte Carlo randomization method, where the ranking scores of each subject
were assigned randomly 1000 times. The expected chance variance was computed as the
standard deviation of the resulting COM distribution. Differences between COM values
larger than the expected variance were deemed meaningful.
2.3.3. Willingness to consider cBCI after the questionnaire—We tested whether
there was a relation between the current number of residual movements a participant had at
the time of the home-visit and their willingness to consider a cBCI after the home-visit. The
residual movements were grouped as ‘eyes’, ‘mouth/head’, ‘hand/arm’, ‘leg/feet/toes’ and
‘residual speech’. If the participant had one or more forms of residual movement pertaining
to one of the groups it would count as 1, otherwise 0. The total number of residual
movements varied between 0 (no residual movement at all) and 5 (able to control at least one
form of movement per group). Linear regression was computed between these factors for
both the NMD and SO groups, to assess if there was a different tendency between the two
groups. The coefficient of correlation (r2) for each regression model is reported.
3. Results
3.1 Demographics
We analyzed responses from 28 participants (median age 53 years old; range 29 to 76 years
old; 14 male). Of these, 13 (46%) were diagnosed with a progressive neuromuscular disease
(NMD, Figure 2A), whereas 15 (54%, Figure 2B) had a sudden onset (SO) event that led to
the locked-in state (see also Supplementary Table 1). In both groups, the number of male
and female participants was similar. The majority of the NMD participants (62%) was older
than 50 years, lived at home (92%) and had heard of or seen a BCI system in the past (85%).
In contrast, the majority of the SO participants (53%) were younger than 50 years old and
lived in a nursing home (53%). Similar to the NMD group, the majority of the SO
participants (87%) were familiar with the concept of a BCI.
Participants scored a median ALSFRS-r of 15 (on a scale from 0 to 48; Figure 2C) and there
was no significant difference in the ALSFRS-r scores between NMD and SO groups (NMD
median of 8; range 2-29; SO median of 16; range 8-22; unpaired two-samples Wilcoxon test,
z=−0.14, rank sum = 185, ns). The overall median duration since diagnosis was 16.5 years
(Figure 2D), and was not significantly different between NMD and SO groups (NMD
median of 14.3 years, range 6.3-49.4 years; SO median 16.8 years, range 2.7-29.5 years;
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unpaired two-samples Wilcoxon test, z=−1.38, rank sum = 158; ns). Of note, the duration
since diagnosis only corresponded with the exact duration of LIS for the SO group, as
individuals with NMD generally entered LIS several months to years after the first
diagnosis.
3.2 Residual movement and current communication channels
All participants had aphonia or severe hypophonia, and quadriplegia or quadriparesis.
Regarding residual movement (Figure 3A), all participants (for both NMD and SO groups)
had preserved sustained eye opening and eye movements. The majority of the participants
had residual movement of the head or mouth (92% and 93% for NMD and SO, respectively)
and/or residual movement of the arm or hand/fingers (54% and 53% for NMD and SO,
respectively). However, the NMD group showed higher counts of preserved leg, foot or toe
movement (46%) and residual forms of speech (e.g., making noises/sounds or saying short
words; 38%) when compared with the SO group (27% and 7%, respectively). The
participants reported using a variety of current communication channels (Figure 3B), from
eye movements to answer closed questions, to letter cards and more sophisticated hardware
switches and eye trackers. Interestingly, letter cards, button switches and head movements
were more used by the SO group than the NMD group. In contrast, NMD participants used
eye trackers and residual forms of speech more than the SO group. The latter is likely related
to the fact that the NMD group had considerably more individuals with preserved forms of
residual speech compared with the SO group (38% against 7%).
3.3 Preferred applications
Participants considered ‘direct personal communication’ the most important application to
be provided by a cBCI, followed by ‘private conversation and writing’ (Figure 4A). ‘General
computer use’ came third, followed by ‘environmental control’. ‘Emotions and facial
expressions’ and ‘artistic expression’ were the two least preferred applications, being
meaningfully inferior to the top 4 applications (difference larger than Monte Carlo variance
0.34). Although the SO group seemed to slightly prefer ‘artistic expression’ (e.g., painting or
making music) when compared to the NMD group, there was no meaningful difference
between the NMD and SO group ratings for any application. Participants were allowed to
suggest other applications besides the ones included in this questionnaire. Most of them gave
specific examples of environmental control (such as controlling a wheelchair, doors or DVD
player) and of specific computer programs (such as a text editor, e-books and games). In
addition, smartphone control (for example for video calls), speech synthesis and alarm
functionality were mentioned.
3.4 Preferred mental strategies
Attempted body movements (‘attempted speech’, ‘attempted hand movement’ and
‘attempted body movement’) were the top-rated mental strategies, whereas ‘counting
backwards’, ‘visual P300’, ‘SSVEPS’ and ‘auditory P300’ were the least preferred strategies
(Figure 4B). Interestingly, the NMD group rated ‘attempted speech’ and ‘attempted hand
movement’ meaningfully higher than the SO group (difference larger than the Monte Carlo
variance 0.28). In contrast, the SO group rated ‘counting backwards’ and ‘visual P300’
higher than the NMD group.
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Regarding ‘attempted body movement’, we asked participants which body part they would
choose to control a cBCI (other than the hand). Toes (38% and 29% for NDM and SO,
respectively) and feet (31% and 22% for NDM and SO, respectively) were the most chosen
body parts (Figure 4C–D). Tongue was the third most chosen body part by both groups.
While the SO group suggested more alternative body parts (arm, head, eyes, hips and elbow)
to toes and feet, the NMD group only suggested one additional body part (arm). When asked
to suggest other mental strategies, the participants suggested visual letter imagination,
laughing, thinking of colors, tastes/smells and walking as mental strategies.
3.5 Time of information
Both groups preferred to learn about and receive ATs when they approach or enter the
locked-in state (Figure 5). While for the NMD group that moment coincides with later stages
of their disease (e.g., no speech and residual movement), for the SO group that is
immediately after onset or during the rehabilitation phase.
3.6 Willingness to consider cBCIs
Lower number of residual movements correlated moderately with an increased likelihood to
consider a cBCI for both NMD and SO groups (r2NMD=0.33; r2SO=0.30) (Figure 6). When
explaining their answer, the participants, most of whom had previous knowledge or
experience with cBCI technology, considered current BCIs to have limited benefit over
current ATs. The majority of these participants reported that they would consider cBCI if
“the speed would match current AT” or when the cBCI would be “faster, have equivalent
applications [to current ATs] and be esthetically good”. Yet, most participants did state that
if residual movement/function deteriorates with time, they would consider a cBCI as an
option.
4. Discussion
In this study we gathered the opinion of Dutch individuals with LIS regarding three aspects
of BCIs for communication (cBCIs): the applications to control with a cBCI, the mental
strategies employed to generate the control signal, and the moment they would like to be
informed about cBCIs. We grouped the participants into neuromuscular disease (NMD) and
sudden onset (SO), and show that preferences of both groups on these aspects correspond to
a large extent.
4.1 Preferred applications
In this study we show that the choice of cBCI applications does not depend on the cause of
LIS. Direct personal communication, private conversation and general computer use were
the top three applications chosen by both groups. This is in agreement with earlier studies
that investigated quality of life in LIS, and that reported a strong relation between quality-of-
life and the ability to communicate 4–6. Regarding environmental control, the 4th most
chosen application, the participants expressed their desire to control the lights, doors,
wheelchairs and DVD players, which is also in correspondence with a previous survey
performed by Huggins and colleagues among individuals with ALS 15. Interestingly, in
contrast to previous studies that suggested that artistic expression is an important BCI tool
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for several individuals with severe motor paralysis 34–38, we found that this application was
one of the least preferred. In the current study, artistic expression may have received a lower
rank because (as in the general population) not all individuals are actively involved in artistic
expression and such application is not provided by all current communication aids, whereas
communication is a universally used concept.
4.2 Preferred mental strategies
Both SO and NMD participants had a strong preference for motor strategies (attempted
speech and movement) over working memory and reactive (evoked) strategies (i.e., visual
P300, SSVEPs and auditory P300). This result demonstrates that individuals with LIS prefer
to use an active rather than a reactive strategy for cBCI control. The somewhat lower
preference of SO participants, compared to NMD participants, for motor-related paradigms
could be related to earlier observations in LIS individuals with pontine, premotor and
parietal lesions were selectively impaired in mental manipulation of, for example, the hands
39–42. Interestingly, one participant, who was paralyzed from birth due to cerebral palsy, said
she “cannot imagine or attempt to make a movement”. This is in agreement with previous
BCI studies with individuals with CP (e.g., 43,44) and with studies that showed that people
with fetal brain damage may experience more difficulty acquiring reliable control of their
motor functions (e.g., 45).
Surprisingly, apart from the hand, toes and feet were the most chosen body parts for cBCI
control, even though only 6 (out of 9 selecting toes/feet) NMD and 2 (out of 7 selecting toes/
feet) SO participants could still move their toes and/or feet to a certain extent. Another
explanation could be the fact that feet are large body parts of which dexterity is
evolutionarily close to the hand46–48 and therefore easy to imagine/attempt control.
Nevertheless, a biased choice for these body parts cannot be completely ruled out as feet and
toes were the first and the last examples of 4 body parts shown in the animation video (“foot,
head, tongue or toes”). This psychological effect is commonly known as the serial-position
effect, where a person tends to recall the first and last items in a sequence best 49.
Taken together, both SO and NMD groups largely agree on preferred mental strategies for
cBCI control. However, the relative stronger preference of the NMD group for attempted
speech and hand movement and of the SO group for counting backwards and visual P300
overtly highlights the need to consider the users’ preference for strategies in future research
on BCIs for communication. Moreover, further investigation on the relation between the
mental strategy preference and actual the cBCI performance using that strategy may be the
key to detect the best features for accurate and stable cBCI control.
4.3 Willingness to consider cBCI
With fewer residual movements available, participants were more likely to the consider a
cBCI after the survey. This trend was slightly more pronounced for the NMD groups, which
is not surprising since these individuals are more likely to lose their current
residual50movements with the progression of the disease. However, the low effect size
indicates that a larger number of participants is required in order to corroborate these
findings. Most of the participants indicated that the current BCIs had limited benefit
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compared with current available assistive technology. As expected, many participants would
consider a cBCI if its speed, accuracy and/or appearance (with respect to non-invasive
setups) would be improved over current available systems. Some participants also expressed
their thought regarding the type of BCI systems currently available. External (non-invasive)
cBCIs were, in general, preferred over internal (implanted) cBCIs (8 against 2, out of 28).
Of the 10 participants who expressed their opinion, two NMD participants were open to the
possibility of an internal cBCI provided that a short hospitalization would be required, which
supports previous studies that reported the strong preference of users for outpatient surgery
15,20,24.
4.4 Time of information
Another topic that has received little attention in the field of BCI is the time of information,
that is the preferred moment when the users would like to be informed about and try cBCIs
as a communication AT-aid. In this study we investigated this subject and found that both
NMD and SO groups have a stronger preference to be informed when they most need an AT,
that is when they reach the locked-in state. Naturally, this yields different time points in the
clinical trajectory of the NMD and SO groups, as patients with progressive disorders have
(or perhaps need) more time to accept their situation and generally only require AT
sometime after diagnosis, while individuals with SO disorders are often faced with
immediate LIS and need AT aids directly. Yet, some NMD participants also expressed their
wished to be informed as soon as possible after diagnosis. This dichotomic result is in line
with the findings of a recent qualitative study on veterans with ALS, which reports that
while many patients described the urgency to be pro-active with respect to BCIs before they
lose muscular control and verbal communication, others prefer to wait for eventual new
technology and to enjoy their remaining time with their family 50. Altogether, our results re-
enforce the idea that the BCI community should play a more active role in informing
rehabilitation centers about cBCIs, such that these can be tested by SO users shortly after the
event.
4.5 Strengths and limitations
In this pioneer study we interviewed 28 Dutch individuals with LIS, which covers an ample
portion of the LIS population in the Netherlands (a total estimated number of 124 patients at
a prevalence of 0.73 patients per 100 000; 2). In this pooled sample the median duration of
paralysis was 16.5 years, indicating that individuals with LIS in the Netherlands live many
years with this condition, which deepens the value of their opinion on cBCIs. Another
strength of this study was the delivery of a questionnaire through structured interviews at the
participants’ home. During the home-visits we had the opportunity to explain the questions
and collect the participants’ opinions with respect to several open questions at their own
pace. Furthermore, for the purpose of this study we designed and validated several animation
videos that introduce and explain several concepts related to cBCIs.
This study also has some limitations. In the last years, a number of studies related to BCI
have been conducted in the Netherlands, including some of the current participants. As a
result, a majority of the participants (86%) was not naive to the concept of BCI before the
questionnaire described here. Although this fact may have influenced our results, we
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explained to the participants during the home-visits that this questionnaire is about an ideal
cBCI and not the ones they experimented with in past (if that was the case). Often caregivers
and family members were present during the user interviews. Even though they were asked
not to answer on behalf of the user, their presence could have theoretically biased the
preferences of the users.
Regarding the mental strategies it cannot be ruled out that some participants have comorbid
cognitive problems that make it difficult for them to use certain strategies. An answer to this
question would require access to medical information or a full evaluation of their cognitive
capabilities, which was beyond the scope of this study. However, the participants’
communication during the home visits did not lead to any suspicion of impaired cognition.
Also, the terms used in this study to describe the time of information were not always
applicable to both he NMD and SO groups. Nevertheless, we believe that the use of the
respective terms is unavoidable considering the different nature of the participants clinical
condition. Lastly, due to the (still) limited sample size, advanced regressive models were not
applied. A larger (and international) cohort would be required in order to statistically assess
the relation between the ranked applications and strategies and observed variables such as
age, duration of paralysis and ALSFRS-r scores. We make the methods in this study openly
available to allow other researchers to run this questionnaire in their user cohort.
5. Conclusion
In this study we investigated the opinion of prospective cBCI users regarding two important
aspects of BCIs for communication: the mental strategies for control and the controlled
output application. We showed that individuals with LIS consider (in)direct communication,
general computer use and environmental control important features of a cBCI and that
attempted speech and movement as a control strategy are preferred over the reactive
strategies, such as P300 and SSVEPs. Moreover, the preferred time to be informed about AT
aids and cBCI is when the user reaches the locked-in state and needs the AT. We believe this
survey provides valuable information to stakeholders in cBCI and AT development and
encourages the involvement of users in the research and development process, ultimately
promoting an optimal cBCI design and reducing risk of technology abandonment.
Supplementary Material
Refer to Web version on PubMed Central for supplementary material.
Acknowledgements
The authors would like to thank the participants for their time and interest in sharing their opinions about BCIs,
Merel Horsmeier for designing and producing the animation videos and Wesley Sewnundun for implementing the
questionnaire in Qualtrics. This research was funded by the ERC-Advanced ‘iConnect’ project (grant ADV 320708)
(NR), Dutch Technology Foundation STW NeuroCIMT project (grant 14906) (NR) and the National Institute On
Deafness And Other Communication Disorders of the National Institutes of Health (U01DC016686) (NR).
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Figure 1 –. Representative screenshots of the animation videos used in the questionnaire.
A total of 9 animations videos were shown to each participant. A) Section 2 of the
questionnaire used an animation video to introduce cBCIs. Three illustrative screenshots of
the video explaining what a cBCI is, how to control it and what can it be used for are shown.
In this video we described the concept of an ideal cBCI that would be 100% accurate and
100% accepted by the users. B) In section 4 of the questionnaire animation videos were
presented to the participants, each describing a different mental strategy. For simplicity,
consistency across mental strategies and to avoid the application biasing the mental strategy,
all videos showed a spelling matrix as a control application (left screenshot) and a button
press (and subsequent letter selection) as a control output (right screenshot). C) Eight mental
strategies described in the questionnaire: attempted hand movement, attempted body
movement (other than hand), attempted speech, counting backwards, visual imagery, visual
P300, auditory P300 and steady-state visual evoked potentials (SSVEPs).
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Figure 2 –. Demographic description of the participants.
The demographic information of the participants (N=28) in this study was extracted from
Section 1 of the questionnaire. The participants were divided into two groups based on the
cause of LIS, namely neuromuscular disease (NMD) or sudden onset (SO). (A-B)
Information (in percentage) about the participants’ gender (male, female), age group (≤ 50
years old, > 50 years old), living situation (at home or in a nursing home) and whether they
were naive to BCI is given for the NMD group (A) and the SO group (B). NMD accounted
for 46% (N=13) of the participants. (C-D) Histogram (in percentage) of the ALSFRS-r score
(C) and duration of paralysis in years (D) per group (NMD in green and SO in yellow). Of
note, at the time of diagnosis, patients with NMD are often still able to move and speak to a
certain extent, hence the exact timing of becoming locked-in (and therefore the duration of
the locked-in state) is unknown for these participants.
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Figure 3 –. Current communication channels and residual movement.
A) Information (in percentage) about the remaining residual movement of the participants
per group (neuromuscular disease, NMD, in green; sudden onset, SO, in yellow) at the time
of the questionnaire. B) Histogram (in percentage) of the currently used communication
channels per group (NMD in green, and SO in yellow).
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Figure 4 –. Preferred applications and mental strategies.
A-B) Ranking (using center-of-mass metric, COM) of preferred applications (A) and mental
strategies (B) possibly supported by a cBCI, by individuals with neuromuscular disease
(NMD, N=13, in green) and sudden onset (SO, N=15, in yellow). Statistical difference
between bars can be evaluated using the Monte Carlo variance indicated on the top right
corner: 0.34 in A and 0.28 in B. C-D) Body parts (other than hand) selected by the
participants during the ‘attempted body movement’ strategy, for both the NMD (C) and SO
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(D) groups. Rating scales ranged from 1 (least preferred) to 6 (most preferred) for A, and
from 1 (least preferred) to 4 (most preferred) for B.
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Figure 5 –. Time of information.
Percentage of participants per group (neuromuscular diseases, NMD, in green; sudden onset,
SO, in yellow) who would like to be informed about AT solutions (including cBCIs) in
different phases after the onset or during the disease progression.
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Figure 6 –. Willingness to consider cBCI.
Linear regression (dashed lines) between the number of residual movements the participant
had at the time of the survey (from 1 to 5, see Figure 3A) and the willingness to consider a
cBCI after the end of the questionnaire (from very unlikely to very likely in a 5-point scale).
NMD participants are indicated with a green cross and SO participants with yellow circle.
The size of the cross/circle indicates the number of participants per coordinate, that is the
larger the cross/circle the more participants. The linear regression equation and
correspondent r2 (per group) are indicated on the top right corner.
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