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

Alessandro Tonin,Aygul Rana,Majid Khalili-Ardali,Andres Jaramillo-Gonzalez,Ujwal Chaudhary,Niels Birbaumer

doi:10.1038/s41598-020-65333-1

Alessandro Tonin, Aygul Rana + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-65333-1

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Journal: Scientific Reports	Publication Date: May 21, 2020
Citations: 16	License type: open-access

Affiliation: University of Tübingen

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.

Highlights

And modern descriptions of ALS disease emphasize that oculomotor functions are either spared or resistant to the progression of the disease[9], and eye-tracking devices can be used to enable patients in the advanced state of ALS to communicate[12,13]
CLIS is an extreme type of LIS, which leads to complete body paralysis, including paralysis of eye-muscles combined with preserved consciousness[6,20]; even if the individuals are incapable of voluntary control of any muscular channels of the body, they might remain cognitively intact[9]
There is a considerable amount of research related to patients in the early stages of ALS who can successfully achieve communication by using gaze-fixation-based assistive and augmentative communication (AAC) technologies or brain-computer interfaces (BCIs)

Summary

Introduction

And modern descriptions of ALS disease emphasize that oculomotor functions are either spared or resistant to the progression of the disease[9], and eye-tracking devices can be used to enable patients in the advanced state of ALS to communicate[12,13]. There is a considerable amount of research related to patients in the early stages of ALS who can successfully achieve communication by using gaze-fixation-based assistive and augmentative communication (AAC) technologies or brain-computer interfaces (BCIs). These patients have intact cognitive skills, residual voluntary movements, intact or partial vision with complete gaze-fixation capabilities. No studies report on the long-term use of EOG or eye-tracking for patients on the transition from LIS to CLIS, and how this progression affects communication capabilities using these AAC technologies. Either in clinical descriptions or technical applications, very little is known about how this LIS to CLIS progression affects the oculomotor capabilities precluding the patient’s communication

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Conclusion