Auditory Electrooculogram-based Communication System for ALS Patients in Transition from Locked-in to Complete Locked-in State

Abstract

Patients in the transition from locked-in (i.e., a state of almost complete paralysis with voluntary eye movement control, eye blinks or twitches of face muscles, and preserved consciousness) to complete locked-in state (i.e., total paralysis including paralysis of eye-muscles and loss of gaze-fixation, combined with preserved consciousness) are left without any means of communication. An auditory communication system based on electrooculogram (EOG) was developed to enable such patients to communicate. Four amyotrophic lateral sclerosis patients in transition from locked-in state to completely locked-in state, with ALSFRS-R score of 0, unable to use eye trackers for communication, learned to use an auditory EOG-based communication system. The patients, with eye-movement amplitude between the range of ±200μV and ±40μV, were able to form complete sentences and communicate independently and freely, selecting letters from an auditory speller system. A follow-up of one year with one patient shows the feasibility of the proposed system in long-term use and the correlation between speller performance and eye-movement decay. The results of the auditory speller system have the potential to provide a means of communication to patient populations without gaze fixation ability and with low eye-movement amplitude range.

EEG power spectral density in locked-in and completely locked-in state patients: a longitudinal study

“…Since the patient 11 still had eye-movement an electrooculogram (EOG) based BCI communication was developed and implemented to provide a means of communication to the patient. The EOG-based communication by patient 11 is described in Tonin et al (2020). As described in Tonin et al (2020), patient 11 was able to employ his eye movement ability to communicate his thoughts and desires until February 2019, albeit with increasing difficulties due to the progressive paralysis of his eye muscles associated with the progression of the amyotrophic lateral sclerosis.…”

“…The EOG-based communication by patient 11 is described in Tonin et al (2020). As described in Tonin et al (2020), patient 11 was able to employ his eye movement ability to communicate his thoughts and desires until February 2019, albeit with increasing difficulties due to the progressive paralysis of his eye muscles associated with the progression of the amyotrophic lateral sclerosis. From February 2019, the patient 11 could not employ his eye-movement to drive the EOG-based communication system (please refer to (Tonin et al 2020) for further details).…”

“…The cardinal feature of a patient in a locked-in state (LIS) is paralysis of most of the voluntary motor function of the body except the oculomotor function with preserved consciousness (Bauer et al 1979;Chaudhary et al 2020a). Because of the preserved oculomotor function and consciousness (Schnakers et al 2008), patients in LIS have several means of communication (Birbaumer et al 1999;Wolpaw and McFarland 2004;Kübler et al 2005;Sellers et al 2010;Lesenfants et al 2014;Wolpaw et al 2018;Tonin et al 2020). A patient can be in LIS because of the severe brain injury or pontine stroke (Sacco et al 2008;Sarà et al 2018;Pistoia et al 2010;Conson et al 2010), or progressive neurodegenerative motor neuron disorders (Birbaumer 2006;Birbaumer et al 2012;Chaudhary et al 2015Chaudhary et al , 2016a.…”

Verbal Communication using Intracortical Signals in a Completely Locked In-Patient

“…In addition, a family judge at patient's home county court gave the permission to proceed with the implantation after reviewing the documented consent and a visit to the patient. The patient began to use the non-invasive eye movement-based BCI-system described in Tonin et al 21 . The Patient was instructed to move the eyes ("eye-movement") to say "yes" and not to move the eyes ("no eye-movement") to say "no".…”

“…To this end, HT and JL and GF were approached in order to prepare the surgical procedure and ensure clinical care in a hospital close to the patient's home. The patient was able to use the non-invasive BCI system employing eye-movement to select letters, words, and sentences until beginning of 2019, as described in Tonin et al 21 . By the time of implantation, the EOG/EEG based BCI system failed, as signals could not be used reliably for any form of communication in this investigational setting.…”