Implante Coclear en paciente sordo y ciego (inglés)

Abstract

In this work, a case study of the first deaf-blind patient implanted with the Combi-40 cochlear implant is analyzed. The patient is a 69-year-old man who has been blind since age 25 and deaf since age 51. Before surgery, his wife used Braille and finger-spelling in his hand to communicate with him. In this study, we intend to show how the rehabilitation program was applied to his particular characteristics and describe the problems we faced throughout the process.
Significant improvements in the dynamic ranges of perception and comprehension of segmental features of speech were observed within two weeks after the setting up. Within four weeks, the patient was able to maintain a simple conversation through the cochlear implant alone, and he abandoned the use of tactile communication. Nowadays, he is able to speak over the phone.
A battery of tests was performed 2, 4 and 6 months after the switch-on. The results obtained for this patient, whose scores are among the best in our experience, suggest that deaf-blind individuals may benefit from a multichannel cochlear implant as an auditory substitute.

Estar sordo sin oir nada, es vivir sin la vida.
Being deaf, hearing nothing, is living without life Anibal A.

Introduction

Multichannel cochlear implants have become a substantial benefit to postlingually deafened patients, many of them growing capable of understanding speech through the cochlear implant alone 1-5. The ability of some patients to recognize speech over the telephone has also been reported by several authors 6-8 .Significant improvements in the ability to communicate have been observed in certain postlingual deaf-blind patients implanted with the multichannel cochlear prosthesis 9-10.
Our cochlear implant experience consists of 43 implanted patients, 14 of whom are children. Thirty-one have been implanted with the Nucleus 22 system 11 ; 2 with the Clarion 12, 2 with the BTE Med-El system 13, 6 with the Combi 40 14-15 and 2 with a device developed in our center at the beginning of the program.
The case of the first deaf-blind patient implanted with a Combi 40 is analyzed in this study. This device is a multichannel 8-electrode system operating in a continuous interleaved sampling strategy 14-15 . In this case, significantly fast changes in communication have been observed since the first weeks of the rehabilitation program.

Method

Subject

The patient, Anibal A, is a 69-year-old man who has been totally blind since age 25. He received his primary school education at a school for the visually impaired. He suffered progressive hearing loss starting at age 43 and used a powerful body-worn hearing aid until age 51, when he became totally deaf. At this time he discontinued the use of his hearing aid. He read Braille, and his wife helped him with both Braille and finger-spelling. Communication with him before the implant was established through his wife. He is a musician and used to play the bandoneon .

Pre-implant data

Standard audiologic studies, audiometry and speech audiometry were performed under headphones. For the left ear, responses were obtained at 70 dB HL at 125 Hz and 90 dB HL at 250 Hz. For the right ear, no responses were obtained at the limit of the audiometer.
Tympanometric studies depicted middle ear normal function with the absence of acoustic reflex thresholds. Vestibular tests showed no responses. Aided scores for the left ear demonstrated only voice detection. No reproducible wave was found in an Auditory-Evoked-Brainstem Responses evaluation.
The promontory electrical stimulation produced auditory responses only in the right ear for burst of biphasic pulses of 100, 200, 400, 800 and 1600 Hz, 300 ms duration. Dynamic ranges were of 2.27; 8.1; 7.3; 12.6 and 11 dB respectively. He was able to assign a different pitch to each stimulus for almost all frequencies. The gap detection test was performed with pairs of bursts of 300 ms duration only at 100 Hz. The patient was unable to detect gaps of less than 250 ms.
An Axial Computed Tomography showed normal inner ear structures.
Psychological aspects of the patient were evaluated in several interviews with both the patient and his wife. The evaluation showed that the patient was mentally active but depressive due to his isolation.

Implant data and post-implant procedure

Taking into consideration the pre-implant tests results, after several multidisciplinary meetings the patient was considered a candidate for cochlear implant. In April, 1995, he was implanted in his right ear with a Combi 40 (8 channels ) system. When the implant was switched-on in June, the instructions were explained by means of both Braille written by his wife, and her finger spelling on his hand. Threshold measurements were very difficult for him at the beginning, mainly due to his preexisting tinnitus. The complete array of electrodes was switched-on with the upper level for each electrode fixed at a medium to comfortable level. Dynamic ranges (measured as the difference between maximum accepted level and threshold) are depicted in Table 1. Channel 1 is for the most basal electrode and channel 8 for the most apical one. The speech processor was re-programmed one week after the switch-on. The upper level for all electrodes was fixed at the maximum comfortable level and balanced in loudness. Then the patient used the new program for 3 weeks. The third fitting was in July; the dynamic ranges of the second and third fittings are also depicted in Table 1. The patient showed improvement in his speech understanding. After this third fitting, the speech processor was re-fitted once a month.

The rehabilitation program included auditory training and psychological assistance for the patient and his family. The auditory rehabilitation was conducted 1 hour a day twice a week for 6 months. During the first auditory training sessions, the psychologist was present in order to coordinate the working sessions and provide emotional support.

The auditory rehabilitation program focused on the performance of the following auditory skills: a) use and adjustment of the speech processor; b) voice source identification; c) detection and recognition of environmental sounds; d) development of suprasegmental features: pitch, loudness and temporal pattern recognition; e) development of segmental features: recognition of words, phrases, phonemes and ongoing speech; f) use of the telephone.

During the initial use of the implant, one of the difficulties the patient encountered was distinguishing between when he was hearing somebody speaking and when he was hearing noises which were not speech sounds. He also referred to hearing voices like “internal voices” or strange noises when nobody was speaking. Another difficulty he had was that his first auditory reception was what might be termed “analytic” due to the fact that he had problems understanding a word as a whole. He was able to identify the phonemes of a word, but unable to perceive the word as a significant unit. He utilized a sort of “auditory spelling”. For instance, when the name of his wife was uttered, he reported hearing each of the letters that composed the name, but not the whole name. That was his auditory reality at the moment.

The reason for this may lie in the fact that as before surgery, Anibal was only able to understand Braille and finger spelling in his hand (which presume discrete methods for speech comprehension), he had developed an “analytic” organization of speech.
The methodology used with this patient was basically the same as that used with sight implanted patients but the resources were adapted to his particular difficulties. To make him understand that what he was hearing was speech, he first read aloud a paragraph. Then, the patient listened to the voice of the therapist reading the same text while he touched her throat with his hand. At first, whenever he took his hand from the therapist’s throat, he would confuse voice sounds with other noises. Once he realized he was hearing speech coming from people next to him and detected a communicative intention in it, his acoustical memory was stimulated. Tactile cues were reduced, and auditory information was almost enough for him to commence with the training in an auditory mode. The same resource was then used to facilitate the integration of speech comprehension and to stimulate the synthetic aspects of the language. Then speech tracking 16 procedures were administered for both training and evaluation purposes.

The patient was evaluated with the Auditory Ability Tests Battery, BaTHA17 and the Monosyllable Identification from the Spanish Early Speech Perception test 18 two, four and six months following the setting up. The tests include: i) Vowel Confusion Matrix: identification among 5 isolated Spanish vowels presented randomly 4 times each; ch = 7 (35%). ii) Question-Statement Recognition: recognition of intonation among 20 phrases; ch = 12 (60%). iii) Pairs of Two-Syllable Identical Words with Different Stress: 16 pairs were administered to the patient in Braille; he was required to identify which word of each pair was presented; ch = 11 (68%). iv) Two-Syllable Word Recognition: recognition of 24 words in open set format extracted from the consonant-discrimination-in-word-context test, which is a three-choice word format; v) Consonant Confusion Matrix: identification of 16 Spanish consonants in /vCv/ context, with v = /a/, presented randomly 4 times each; ch = 7 (11%). vi) Ongoing Speech using speech tracking measures: different texts of about 100 words each, were used for every speech tracking measurement.

All the tests were presented aloud by the therapist who sat one meter in front of the patient in a quiet room. The speech material was presented at a comfortable listening level using the retroauricular microphone of the speech processor.
In the first evaluation of the test v), each consonant was presented only once, to avoid tiring the patient, who was unable to pay attention for long periods of time. The ii) test could not be administered because the patient had difficulties understanding the instructions.
The patient started using the telephone about four months after the switch-on.

Results

The dynamic ranges for each electrode expanded in successive fitting sessions due to both decreases in thresholds and increases in the maximum comfortable levels.
In the second programming session, one week after the first one, the patient was able to discriminate the pitch of adjacent electrodes; after training, he recognized which electrode (1 to 8) was stimulated and made a fine loudness balance among electrodes. He could also recognize some old melodies played on a wooden flute (recorder).
After this fitting, Anibal began to recognize some familiar voices, claps and key noises without previous presentation. He also began to play some melodies he recalled on the bandoneon, was able to count the number of stimuli he heard even if they were soft, and recognized different familiar names in a closed-set.
After the third fitting, his wife abandoned the use of finger spelling, and he was able to establish a casual conversation just by talking. At this point, his communication with the speech therapist was more fluent than with the rest of the team. Two months later, he showed significant improvement in his auditory comprehension with unfamiliar people as well.
Table 2 shows the percentages obtained in the longitudinal studies. Scores were above chance on all the tests. The results which are self-explanatory, displayed improvements on almost all the tests.

Discussion

To implant a deaf blind individual was a great challenge for all of us. In spite of the experience of the team, it was very difficult to predict results because he was our first patient with dual sensory deprivations. Several meetings involving all the members of the group and an evaluation of the experiences of other centers 9 – 10 helped us make a decision.
The beginning of a cochlear implant rehabilitation program involves auditory as well as visual cues. During this stage, most of the patients have difficulty realizing where sounds come from, and identifying the source of what they are hearing. They are not able to relate these sounds with the appropriate phonemes and words. Visual cues are used as an aid to hearing. With training, some visual cues are, in most of the patients, replaced by auditory cues. As with our patient the use of such cues is not applicable, during the first days of use of the cochlear implant, we simultaneously used auditory and tactile resources. With training, the tactile cues were replaced by auditory ones.
Throughout this process, he suffered depression and had aggresive attitudes, probably due to his age and the shock produced by his first hearing sensations through the implant. His expectations were not fulfilled in the first days of use of the prostheses, and intensive psychological assistance was required.
Some of our implanted patients comment that at the beginning of the use of their prostheses, they feel as if somebody other than the person they are seeing is speaking inside the speech processor, and that some background noise is quite similar to speech sounds. If we relate these experiences with those mentioned by Anibal in the first days of the use of his implant, his “internal voices” could, perhaps, be explained as real voices or background noises, invisible to him.
Progress in his rehabilitation program and successive fittings of his speech processor helped him achieve better identification of the acoustical message and improve his communication.
Our rehabilitation program required successive modifications. However, despite moments of discouragement for all those involved, day by day it became easier for Anibal to achieve a higher level of communication.

Conclusion

A cochlear implant could be a real benefit for a deaf-blind patient, considering all the social implications involved in allowing him to communicate with other people by talking. It might also provide some spatial cues related to auditory information, such as allocation of sound sources and sense of distances. This observation could mean that a sort of sensory substitution or completion might occur in a deaf-blind patient for whom deafness has been reduced or minimized by a cochlear implant.
Just as reported by Martin et al., in spite of his aetiology and age, Anibal did as well as, or better than, the many normally sighted cochlear implant patients we have.

General comments

We would like to reproduce here (with Anibal’s permision), some comments and feelings expressed by Anibal (A) in a voluntary talk with a member of the team (B). We think that it could be a contribution to the interdisciplinary work involved in a cochlear implant team and a way to encourage its members in this magnificent venture.

27/12/95
B. Anibal, we would like to know how you feel about your CI; do you think that the implant has brought about changes in your life?
A. I feel like another man. When somebody doesn’t hear, he feels shut out of the world. Being able to hear again, as I am hearing now, is to renew life. I don’t know if you are following what I mean to say.

B. Of course, I understand you. You are quite clear.
A. A blind person creates a blind world for himself, and he can live a normal life, but a deaf-blind person cannot live a normal life. It is a very hard situation, very hard. It is so sorrowful that one wants to leave life……, in a word…..

B. Now that you hear, you feel more…
A. (he interrupts) Now my life is totally different! I feel like another man. I would like to fight for goodness, for welfare. Before, I felt bitter; now I feel revived.
I feel like I felt before, a long time ago, when I could hear. I feel so good! The only problem I have ….I want to apologize for this…..I would like to find a job, to be useful in some way… but I am old, and I have a cochlear implant….it could be very difficult to find a job. But I feel so well, …..as if I was 50, and I am in good enough shape to work.

B. Perhaps, the real obstacle to finding a job is the current economic situation in our country; the recession.
A. Yes!. unemployment is a problem all over the world. I read that recently.

B. Anibal, I would like to know if it is possible for you to detect where the sounds come from; the distance; if the sounds come from near or far.
A. Look Leonor, I’m not sure yet. For me, almost all the sounds are near the coil, in the coil. But I can tell if the sound comes from very far or very near. Right now I hear the air conditioner as if it was high over my head. Where is it?

B. It is in another room.
A. Ah! I need time.I still don’t have a clear sense of distance. Do you think that the sensitivity key could help me be more aware of the distances of the sounds?

B. Of course it can. Silvia explained the way this key is used to you.
A. Yes, I will also use it to figure out distances. I think that I could relate the distance with the loudness and with the number on the sensitivity key. Oh! now I remember that when I hear the steps of a person walking, I know if this person is approaching me, and when he goes away from me I can hear his steps growing softer. Yes, I have some sense of distance!

B. Now, Anibal I want to ask you some questions but, please, feel free to answer me or not. You are not obliged to answer me.
A. I will never refuse to answer you. This is important for all of us.

B. Now that you have your implant, do you think it could help you to remember some things, to remember things you saw before?
A. I do not understand. Do you mean if I remember sounds that I heard?

B. No. I mean… I don’t mean to associate memories with what you have heard but with what you saw before, when you could see….
A. When I could see? Oh! I have many memories.

B. Now that you have your implant can you revive those memories? Does hearing help you to remember certain things? Have you ever thought about it?
A. It has made me remember many things, but I don’t think they are important enough to mention, I do not speak about it. But it has made me remember many things about myself from my past when I could hear and when I couldn’t. Good things and bad things. And it has even suggested something to me for the future.

B. Do you just remember voices or images as well?
A. Both things; voices and images. As I told you, the implant has been a renovation for me. In the future will I be able to understand speech when somebody else is speaking at the same time? With music I can understand speech very well; also with background noise, but not with other voices. I want to tell you something. When I awake in the midnight and switch-on my device, I hear something like the sound of the sea. As if I was on board a ship.

B. I think that you are hearing the sound of silence…

References
1. Waltzman SB, Cohen NL, Shapiro WH. Long-term effects of multichannel cochlear implant usage. Laryngoscope 1986;96:1083-1087.
2. Dorman MF, Hannley MT, Dankowski K, Smith L & McCandless G. Word recognition by 50 patients fitted with the Symbion multichannel cochlear implant. Ear Hear 1989;10:44-49.
3. Dowel RC, Mecklenburg DJ, Clark GM. Speech recognition for 40 patients receiving multichannel cochlear implants. Arch Otolaryngol Head and Neck Surg 1989;112:1054-1059.
4. Tye-Murray N , Tyler RS. Auditory consonant and word recognition skills of cochlear implant users. Ear Hear 1989;10:292-298.
5. Tye-Murray N, Tyler RS, Woodworth GG, Gantz BJ. Performance over time with a Nucleus or Ineraid cochlear implant. Ear Hear 1992;13:200-209.
6. Brown AM, Clark GM, Dowell RC, Martin LFA, Seligman PM. Telephone use by a multi-channel cochlear implant patient. J Laryng Otol 1985;99:231-238.
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Acknowledgements

The authors would like to thank Anibal for his participation in this study and for the beautiful things he taught us. We also would like to thank Dominga, his wife, for the patience and kindness she had with all the members of the team.

Table 1 -Dynamic ranges in dB for the first, second and third fittings, for the 8 electrodes.
Electr. #1
Electr. #2
Electr. #3
Electr. #4
Electr. #5
Electr. #6
Electr. #7
Electr. #8
First fitting
10.2
8
6.7
9.7
8
9
10.1
7.2
Second fitting
16.2
14.8
13.5
16.3
15.2
16.3
16.7
17
Third fitting
16
18.3
17.2
22
21.4
21
21
20

Table 2 – Speech battery scores performed two, four and six months after the setting up, in auditoy only condition. Fluent speech was measured in words per minute (wpm).
% Correct at 2 mo
% Correct at 4 mo
% Correct at 6 mo
vowel confusion matrix
N = 20 ch = 7 (35%)
100
95
100
question – statement
N = 20 ch = 12 (60%)
100
85
two-syllable identical words different stress
N = 16 ch = 11 (68%)
95
81
100
two-syllable word recognition
N = 24
83
75
87
consonant confusion matrix
N =64 ch = 7 (11%)
70 *
73
64
ongoing speech
29.3 wpm
37.41 wpm
44.36 wpm
ESPMonosyllable Identification
Category 5
Category 5
Category 5
p<0.05

* N=16 ch = 3 (18%) p< 0.01