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Donald B. Egolf, Ph.D.
Department of Communication
1117 Cathedral of Learning
University of Pittsburgh
Pittsburgh, PA 15260
Phone: (412) 624-6763
Fax: (412) 624-1878
Finding a reliable motoric response can be a difficult task when one is teaching a nonspeaker how to use an augmentative communication device. The difficulty of the task is intensely magnified and at times seems insurmountable in the case of Locked-In-Brain Syndrome (LIBS). The National Institute of Neurological Disorders and Stroke (1) defines LIBS as a rare neurological disorder characterized by complete paralysis of voluntary muscles in all parts of the body except for (but not always) those that control eye movements. Individuals with LIBS are conscious and can think and reason but are unable to speak or move. The chief causes of LIBS are traumatic brain injury, stroke, degenerative diseases such as ALS, and medication overdoses.
Although no precise incidence data are available, because LIBS is not always differentially diagnosed and is often confused with coma, it is estimated that there are 25000 LIBS patients in the USA with approximately 500 of these totally locked-in, having absolutely no motor responses including eye movements (2).
Methods for teaching LIBS patients to communicate fall into one of two categories: the noninvasive and the invasive, the former being clinical, the latter, experimental.
Key practitioners of the non-invasive method are from the research group of the University of Tubingen in Tubingen, Germany. With LIBS patients with residual eye movements, eye movement is used to communicate by scanning in face-to-face situations. By "scanning" is meant that the patient is presented with an array of items and is asked to signal "yes" or "no" with the eyes for the items. For example, a common scanning technique presents letters to the patient one at a time. The patient will then signal with the "yes" response if the letter presented is the one needed by the patient to spell a particular word. Scanning is often called the "20-questions" method. To enable these same patients to communicate when alone, say in typing, brain waves are utilized. Brain waves are utilized as well for LIBS patients who are totally locked in. The brain waves utilized are not any of the familiar ones, beta, alpha, theta, or delta, for example, but are much slower, not measured in fractions of seconds, but in seconds. The Tubingen group (3) describe the brain responses as slowly varying potential shifts in the brain which are known as slow cortical potentials (SCPs). Training a LIBS patient to communicate using SCPs requ! ires that the patient intentionally produce binary responses which can be used to signal "yes" and "no." These opposing SCP responses seem to be best triggered by thoughts of anticipation and release respectively. For example, if you imagine that you are a sprinter waiting in the sprinter's crouch just before the race, your anticipation will produce a negative SCP response, but then when you imagine that you hear the starter's gun and you begin to sprint you will produce a positive SCP response. These negative and positive responses can of course then serve as "no" and "yes" responses (4). And, once having a repertoire of yes/no responses, communication by scanning is possible.
Herzog (5) has written an extensive case study of a LIBS patient, a young Cornell student, who learned to communicate with trace eye movements that signaled "yes" and "no." Included in the case study are reports of traumatic events in the patient's life attributable to staff ignorance or insensitivity. For instance, not all hospital staff members were informed of the patient's eye-movement communication code. As a result when these staff members came into the patient's room and the patient tried to communicate with her eyes, the uninformed staff members thought that she was just being cute. And, one night, for example, a podiatrist actually ripped off one of the patient's toenails without anesthesia. The pain was unbearable and the patient could say nothing or do nothing.
Parker (2) has written a detailed case study of a totally LIBS patient as well as a biographical profile of the patient's therapist, neurosurgeon Niels Birbaumer, a member of the Tubingen research team. Teaching the totally LIBS patient is somewhat like conducting a polygraph examination. You must begin by repeatedly asking control questions, questions to which you know the answers, "Are you a man?" "Are you married?" and so on. This is to ensure that responses are both valid and reliable. When the patient can reliably and correctly answer the questions with SCP brain-wave yes/no responses, then relevant questions are asked, questions for which answers are unknown. Following this, training can move to having the patient initiate conversation, and communicate when alone. Brain-wave responses are fed to a computer interface called a Thought Translation Device (TTD) which then feeds to a voice chip for speech or word processor for written communication(6). The process is a slow o! ne. One hundred characters can take the better part of an hour (4).
The invasive method designed to enable LIBS patients to use their brain waves to interface with a computer to communicate involves the implantation of electrodes into the patient's brain. A pioneer in this area is Phillip Kennedy of Emory University (7). Kennedy's approach is experimental requiring FDA approval for each new small cohort of patient participants. The goal of this method is the same as the non-invasive method, that is, to have a LIBS patient produce reliable binary responses so communication is made possible by scanning a list of alternatives (letters, words, etc.). It is hoped that the implantation technique will produce a brain-computer interface that can make patient communication training easier, shorter, and, at the same time, can enable the LIBS patient to produce more reliable and valid responses than with the non-invasive method.
Whatever the method used in attempting to enable LIBS patients to communicate, the task is a daunting one. And, the task is embedded in a much larger cluster of issues relating to the thoughts and feelings of the LIBS patient. A key question LIBS patients often ask is, "Is life worth living in the LIBS state?" It is important that any communication specialist who works with LIBS patients be aware of this larger cluster of issues as they attempt to evoke meaningful communication responses from the LIBS patient.
1. The NINDS website (http://www.ninds.nih.gov)
2. Parker, I., "Reading Minds," The New Yorker, January 20, 2003, 52-63.
3. Rockstroh, B., et al., Slow Cortical Potentials and Behavior, Baltimore: Urban and Schwarzenberg, 1989.
4. Winters, J., "Communicating by Brain Waves," Psychology Today, May/June, 2003.
5. Herzog, B., "Locked In," Cornell Magazine Online, July/August, 1999.
6. Hinterberger, et al., "A brain-computer interface (BCI) for the locked-in comparison of different EEG classifications for the thought translation device," Cllinical Neurophysiology, 114(3), 2003, 416-425.
7. The ALS website (http://www.lougherigdisease.net)
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