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 Table of Contents  
CASE REPORT
Year : 2019  |  Volume : 25  |  Issue : 1  |  Page : 43-45

Difficulties and challenges encountered in old-aged cochlear implantee with long sound deprivation period: A case study


Department of Otolaryngology, PGIMER, Chandigarh, India

Date of Web Publication19-Jun-2019

Correspondence Address:
Dr. Sanjay Kumar Munjal
Department of Otolaryngology, PGIMER, Chandigarh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_116_17

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  Abstract 


Old age and long sound deprivation are often considered as negative factors in the selection of candidacy for cochlear implantation. We hereby report a case that was implanted at the age of 61 years with a sound deprivation period of 22 years. The initial postimplantation period was too tormenting for the case as she persistently reported the presence of internal disturbing sounds (similar to tinnitus) and could not appreciate the presence of speech. Repeated counseling sessions, intensive auditory training, and modifications in mapping parameters helped in improving her speech perception as well as a reduction in tinnitus. The various difficulties and challenges encountered in implantation in old age with long sound deprivation period are hereby discussed, and modalities to overcome them are suggested.

Keywords: Cochlear implant, mapping, sound deprivation


How to cite this article:
Munjal SK, Kumar R, Sharma A, Banumathy N, Panda NK. Difficulties and challenges encountered in old-aged cochlear implantee with long sound deprivation period: A case study. Indian J Otol 2019;25:43-5

How to cite this URL:
Munjal SK, Kumar R, Sharma A, Banumathy N, Panda NK. Difficulties and challenges encountered in old-aged cochlear implantee with long sound deprivation period: A case study. Indian J Otol [serial online] 2019 [cited 2019 Sep 19];25:43-5. Available from: http://www.indianjotol.org/text.asp?2019/25/1/43/260717




  Introduction Top


The cochlear implant (CI) in elderly is usually not preferred and prohibited due to surgical risks, age-related degeneration of both central and peripheral auditory system and overall cost to benefit ratio.[1],[2] The cochlear implantation in elderly can be challenging because the duration of hearing loss and auditory deprivation in elderly can decline the perception which can result in permanent cognitive declination as well as a detriment to physical health, mental health, independence, social interaction, and quality of life.[3] The long-standing hearing loss due to morphological and physiological changes in cochlea can lead to changes in central auditory nuclei; also reduces synaptic activity within the auditory cortex in a layer and in specific manner causing auditory deprivation.[4],[5],[6] The suprathreshold speech recognition remains poor in spite of providing amplification with better-aided thresholds, which is not due to poorer audiometric thresholds rather due to auditory deprivation.[7] Tinnitus can exist with or without hearing loss which can range from barely noticeable to debilitating and its prevalence increases with age. The tinnitus can have impact on communication and the quality of life where a subject has difficulty in focusing, distracted thoughts, and decreased self-esteem.[8] Such patients may require attention on some specific preventive healthcare strategies to improve their listening ability.


  Case Report Top


The case IK reported at the age of 61 years with bilateral profound sensory neural hearing loss (drug-induced) with complaints of inability to hear and ringing type of tinnitus perception for the pat 22 years. Preoperatively, the detailed audiologic evaluation was performed in an acoustically treated double walled audiometric room which conform to the ANSI/ISO standards for the maximum permissible noise levels using ORBITER 922 Clinical audiometer, MAICO MI34 Tympanometer and Intelligent Hearing System (2125) evoked potential otoacoustic emission measurement systems. The pure-tone audiometry average (500 Hz, 1000 Hz, and 2000 Hz) was >110 dB HL and type “A” tympanogram was observed in both ears. Transient otoacoustic emissions and distortion product otoacoustic emissions were absent in both ears. In either ear, no definable Wave-V could be observed at 99 dB nHL in auditory brainstem evoked response audiometry. With hearing aids, the word recognition score (WRS) was nil, and the aided thresholds were >80 dB HL in both ears. The subject was relying on written mode of language for communication. Tinnitus handicap inventory (THI) score was 69 and indicative of grade 4 tinnitus, and the severity perception of tinnitus was loud. The subject was implanted with Nucleus CI24R (ST) CI with Sprint processor in the right ear. There was complete insertion of all active electrodes with the intraoperative impedance ranging between 4.97 and 8.51 kΩ across electrodes.

Postoperative

After “switch on” and initial mapping, the aided thresholds of the implantee were between 25 dB HL and 45 dB HL on the tested frequency (500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, and 8000 Hz). The parameters used during mapping are shown in [Table 1]. The WRS was 20%–30% at the end of 1 month after switch on.
Table 1: Mapping parameters at switch on

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After 1-month post-switch on although the THI score decreased to 48 (Moderate handicap-Grade 3 tinnitus), the subject still complained that the perception of persistent ringing in ear was interfering in her ability to comprehend the speech. The mapping parameters namely rate of stimulation was changed to 250 pps; “C” and “T” levels were changed, and a marginal improvement in speech perception and tinnitus severity was observed (WRS increased to 40%). Subsequently, over a period, the rate of stimulation was changed to 500 pps; the “C” and “T” levels changed a little [Figure 1] and [Figure 2] but an improvement in speech perception and decrease in tinnitus severity was observed. The THI score decreased to 10 (Slight handicap-Grade 1 tinnitus), and WRS also increased to 70%–80%.
Figure 1: Variations in C levels across sessions. (E1, E6, E11, E22 are electrode numbers)

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Figure 2: Variations in T levels across sessions

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The subject was explained regarding the pre- and post-operative differences in audiogram and audition. Her fears regarding electrical hearing were alleviated through counseling techniques. Training was also provided for the desensitization of tinnitus. The subject was given intensive auditory training sessions lasting for 45 min duration, thrice in a week. The subject was also “taken off” from the written mode of communication and asked to put more effort on audition alone. Subsequently, the subject also started managing the basic telephonic calls.


  Discussion Top


Long-term hearing loss can lead to sound deprivation wherein patient can have reduced speech discrimination ability. In the present case, the subsequent changes made in mapping (stimulation rate) and auditory training for a period brought a gross improvement in WRS ability and reduction in loudness perception of tinnitus on THI. Stimulus signal in the CI processor is sampled in three aspects, namely frequency, intensity, and temporal aspects and delivered to the corresponding electrode site. The temporal and intensity aspects are modulated by changing rate and current level respectively through each channel. Plant et al. and Weber et al. have reported no significant difference in discrimination ability between higher and lower rates of stimulation.[9],[10] However, in the present case, the rate of stimulus was changed from high 900 pps to low 200 pps followed by 500 pps. The significant improvement was observed in speech perception and speech discrimination score in quiet as well in noisy situations, using 500 pps rate of stimulation. When the rate of stimulation or pulse rate is increased, it results in improvement in understanding the part of spectrum of signal where pulses are placed more closely which can carry the temporal fine structures more precisely. At higher stimulation rate, the auditory nerve discharges can phase lock which sets an upper bound on bandwidth of any signal that can be encoded over a nerve fiber. The phase locking of the auditory nerve discharges is an important cue for the formant frequencies to discriminate speech under some circumstances.[11] Arora et al. have also reported the best discrimination ability at 500 pps/Channel.[12] Likewise, Vandali et al. and Balkany et al. have also observed similar results using ACE speech coding strategy and preferred low-to-moderate (250 pps and 807 pps/channel) instead of higher rate of stimulation.[13],[14] The decrease in reduced perception of loudness of tinnitus in this case probably occurred due to the masking effect of environmental noise. It has been postulated that the stimulation of the cochlea induces vibration of the basilar membrane at the damaged site which suppresses the abnormal activity of the cilia cells of the cochlea and produces the masking effect.[13],[14] Studies have also revealed that tinnitus is linked to abnormal hyper excited brain activities which are likely caused by absent or disordered auditory signal and modulated by the limbic system.[15],[16],[17] The electrical stimulation of the cochlea after implant and counseling sessions both in combination can be used to break the bridge between tinnitus and limbic system.[18]


  Conclusions Top


The case study shows that auditory neurons are preserved and electrically excitable despite years of inactivity. The change in mapping parameters might be required as the neurons might respond at slower rate due to aging and long sound deprivation period. It is crucial not to exclude elderly patients from CI surgery even though deafness duration may have been long. However, the duration of significant outcome might be longer as compared to younger postlingual adults. Therefore, the preimplant counseling for realistic expectation and postimplant counseling for longer “wait-in period” should be taken into consideration.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Waltzman SB, Cohen NL, Shapiro WH. The benefits of cochlear implantation in the geriatric population. Otolaryngol Head Neck Surg 1993;108:329-33.  Back to cited text no. 1
    
2.
Shin YJ, Fraysse B, Deguine O, Valès O, Laborde ML, Bouccara D, et al. Benefits of cochlear implantation in elderly patients. Otolaryngol Head Neck Surg 2000;122:602-6.  Back to cited text no. 2
    
3.
Lin FR. Hearing loss and cognition among older adults in the United States. J Gerontol A Biol Sci Med Sci 2011;66:1131-6.  Back to cited text no. 3
    
4.
Moore JK, Niparko JK, Miller MR, Linthicum FH. Effect of profound hearing loss on a central auditory nucleus. Am J Otol 1994;15:588-95.  Back to cited text no. 4
    
5.
Hardie NA, Shepherd RK. Sensorineural hearing loss during development: Morphological and physiological response of the cochlea and auditory brainstem. Hear Res 1999;128:147-65.  Back to cited text no. 5
    
6.
Kral A, Hartmann R, Tillein J, Heid S, Klinke R. Congenital auditory deprivation reduces synaptic activity within the auditory cortex in a layer-specific manner. Cereb Cortex 2000;10:714-26.  Back to cited text no. 6
    
7.
Gelfand SA, Silman S, Ross L. Long-term effects of monaural, binaural and no amplification in subjects with bilateral hearing loss. Scand Audiol 1987;16:201-7.  Back to cited text no. 7
    
8.
Lockwood AH, Salvi RJ, Burkard RF. Tinnitus. N Engl J Med 2002;347:904-10.  Back to cited text no. 8
    
9.
Plant K, Holden L, Skinner M, Arcaroli J, Whitford L, Law MA, et al. Clinical evaluation of higher stimulation rates in the nucleus research platform 8 system. Ear Hear 2007;28:381-93.  Back to cited text no. 9
    
10.
Weber BP, Lai WK, Dillier N, von Wallenberg EL, Killian MJ, Pesch J, et al. Performance and preference for ACE stimulation rates obtained with nucleus RP 8 and freedom system. Ear Hear 2007;28:46S-8S.  Back to cited text no. 10
    
11.
Sachs MB, Young ED. Encoding of steady-state vowels in the auditory nerve: Representation in terms of discharge rate. J Acoust Soc Am 1979;66:470-9.  Back to cited text no. 11
    
12.
Arora K, Dawson P, Dowell R, Vandali A. Electrical stimulation rate effects on speech perception in cochlear implants. Int J Audiol 2009;48:561-7.  Back to cited text no. 12
    
13.
Vandali AE, Whitford LA, Plant KL, Clark GM. Speech perception as a function of electrical stimulation rate: Using the nucleus 24 cochlear implant system. Ear Hear 2000;21:608-24.  Back to cited text no. 13
    
14.
Balkany T, Hodges A, Menapace C, Hazard L, Driscoll C, Gantz B, et al. Nucleus freedom North American clinical trial. Otolaryngol Head Neck Surg 2007;136:757-62.  Back to cited text no. 14
    
15.
Loizou PC, Poroy O, Dorman M. The effect of parametric variations of cochlear implant processors on speech understanding. J Acoust Soc Am 2000;108:790-802.  Back to cited text no. 15
    
16.
McKay CM, Remine MD, McDermott HJ. Loudness summation for pulsatile electrical stimulation of the cochlea: Effects of rate, electrode separation, level, and mode of stimulation. J Acoust Soc Am 2001;110:1514-24.  Back to cited text no. 16
    
17.
Brackmann DE. Reduction of tinnitus in cochlear-implant patients. J Laryngol Otol Suppl 1981;(4):163-5.   Back to cited text no. 17
    
18.
House WF. Cochlear implants. Ann Otol Rhinol Laryngol 1976;85 Suppl 27:1-93.  Back to cited text no. 18
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1]



 

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Introduction
Case Report
Discussion
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