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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 25  |  Issue : 2  |  Page : 85-89

Effects of radiological abnormalities in temporal bone and brain on auditory outcomes in cochlear implant recipient children


1 Department of ENT, INHS Jeevanti Hospital, Vasco, Goa, India
2 Department of ENT, INHS Asvini Hospital, Mumbai, Maharashtra, India

Date of Web Publication16-Aug-2019

Correspondence Address:
Dr. Vishal Gaurav
INHS Jeevanti Hospital, Vasco - 403 802, Goa
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_122_18

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  Abstract 


Introduction: Cochlear implantation (CI) is used for rehabilitation of children with bilateral severe-to-profound sensorineural hearing loss. Recently, treatment of such children has been influenced by diagnostic technological advances. Multiple radiological abnormalities detected in temporal bone and brain are now increasingly included for CI. The primary aim of this study was to determine the effects of “radiological abnormalities in temporal bone or brain” on CI outcome. Aim: The primary aim of this study was to determine the effects of “radiological abnormalities in high-resolution computed tomography (HRCT) temporal bone or magnetic resonance imaging (MRI) brain” on CI outcome. Study Design: Prospective study. Setting: Tertiary care center. Materials and Methods: In this study, we evaluated fifty cochlear-implanted children from October 2011 to March 2013. The case group consisted of 15 (30%) children with radiological abnormalities and control group consisted of 35 (70%) children with no radiological abnormalities in HRCT temporal bone or MRI brain. All patients received auditory and speech rehabilitation, and their auditory perception outcomes 1 year after CI were evaluated. The children were assessed by categories of auditory perception (CAP) and Meaningful Auditory Integration Scale (MAIS) tests. Results: There was significant reduction in mean auditory perception outcomes (decreased 6.9% mean CAP and 5.4% mean MAIS scores) at 1 year post-CI in CI recipients who had radiological abnormalities, in comparison to those who had no radiological abnormalities in temporal bone or brain (P < 0.05). Conclusion: In this study, presence of radiological abnormalities in temporal bone or brain was found to have a significant deleterious effect on auditory perception outcome at 1 year after CI surgery in children. However, CI was still helpful in these children. Hence, knowledge of “radiological abnormalities in temporal bone or brain” can provide reasonable help in predicting the auditory perception outcome for CI candidates.

Keywords: Auditory perception outcome, categories of auditory perception, cochlear implant, Meaningful Auditory Integration Scale, radiological abnormalities in high-resolution computed tomography temporal bone or magnetic resonance imaging brain


How to cite this article:
Gaurav V, Rajguru R. Effects of radiological abnormalities in temporal bone and brain on auditory outcomes in cochlear implant recipient children. Indian J Otol 2019;25:85-9

How to cite this URL:
Gaurav V, Rajguru R. Effects of radiological abnormalities in temporal bone and brain on auditory outcomes in cochlear implant recipient children. Indian J Otol [serial online] 2019 [cited 2019 Sep 19];25:85-9. Available from: http://www.indianjotol.org/text.asp?2019/25/2/85/264672




  Introduction Top


The variability in outcomes for cochlear implant recipient children has been the subject of various studies. Researchers have proposed many predictors of auditory perception in an attempt to set realistic expectations and rehabilitation goals for these children. The majority of children who are implanted at a young age display significant gains in spoken language development over time. However, there is still more variability in the language development of deaf children with cochlear implants. There are still some children who obtain little benefit from their cochlear implant and with the population of implant candidates becoming increasingly younger, it becomes more difficult to assess which children will be successful. In this study, we explore a demographic variable of “radiological abnormalities on high-resolution computed tomography (HRCT) temporal bone or magnetic resonance imaging (MRI) brain” and its effect on auditory perception outcomes in children receiving cochlear implant at an Indian tertiary care center which may explain to some extent the variability in language achievement in cochlear implant users.

Cochlear implantation (CI), over the last more than three decades, has become the treatment of choice for individuals with severe-to-profound hearing loss who derive minimal benefit from conventional hearing aid use. The use of multiple electrode cochlear implants in hearing-impaired children is now firmly established as a safe and effective means for improving auditory detection and discrimination when benefit from conventional amplification is limited. A primary goal of CI is to enable a child to use these improved auditory abilities for the comprehension of speech and for developing spoken language. The development of functional spoken language would be considered by most clinicians, teachers, and parents to be a major long-term aim of the cochlear implant procedure. It is clear, however, that a properly functioning cochlear implant does not guarantee this outcome. The detection and discrimination of sound does not ensure that a child will be able to adequately assemble the complex stream of auditory information in connected speech into meaningful language.[1]

On the other hand, it is reasonable to assume that the perception and comprehension of speech is an important ingredient in the development of spoken language, and measure of auditory perception will have some relationship with speech and language abilities. The measurement of auditory perception also provides direct evidence of the assistance provided by the cochlear implant system.[2] Hence, one of the most direct ways to determine benefit with a CI is by demonstrating improvement in auditory perception.

There are various international studies on patient and surgical variables affecting auditory perception outcomes after cochlear implant surgery.[3],[4] However, adequate Indian data are not available. This study may provide useful information for counseling Indian families considering CI for their child in the presence of a radiological abnormality in temporal bone or brain.


  Materials and Methods Top


Study design and participants

This prospective study was performed on a total of fifty children with bilateral severe-to-profound sensorineural hearing loss (SNHL) that underwent CI at an Indian tertiary care center between October 2011 and March 2013. The children who were selected for control group included the following criteria: (1) Permanent congenital SNHL, (2) onset of hearing loss before 6 months of age, (3) the use of amplification and/or intervention program emphasizing spoken language, (4) the maximum age of 10 years old, (5) without any evidence of radiological abnormalities on HRCT temporal bone or MRI brain, and (6) undertaking rehabilitation at a tertiary care hospital after their CI. We enrolled all children who had undergone CI and then divided them into two groups based on radiological abnormalities in HRCT temporal bone or MRI brain. Every patient was assessed by a clinical psychologist, an audiologist, a pediatrician, and a speech/language pathologist.

Intervention

CI is usually performed on children with bilateral severe-to-profound SNHL. Hearing skill refers ability to understand voices which are assessed by categories of auditory perception (CAP) and Meaningful Auditory Integration Scale (MAIS) scores [Table 1] and [Table 2]. The bilateral severe-to-profound SNHL was confirmed by pure speech audiometry, auditory brainstem response with click and tone burst methods, transient-evoked otoacoustic emissions, and distortion-product otoacoustic emissions. None of the children had the experience of speech perception from properly fitted high-gain hearing aids. All the patients received audiological, speech perception, language skills, neurological, and psychological assessment immediately before CI. The imaging study consisted of HRCT temporal bone or MRI brain performed for finding the central nervous system and temporal bone abnormalities. The Nucleus 22 and Advanced bionics Clarion HiRes 90K device and their respective speech processor systems were used routinely. Surgical approach consisted of cortical mastoidectomy under general anesthesia. By posterior tympanotomy, the middle-ear space was entered. Then, the bone surrounding the round window was cut and its membrane was perforated to drain the endolymph. Finally, electrodes using the “advance off-stylet insertion technique,” were inserted into the cochlea. After insertion, correct placement of electrodes was examined by intraoperative neural response telemetry/neural response imaging and postoperatively by X-ray mastoid (Modified Stenver's view).
Table 1: Categories of Auditory Perception Scale

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Table 2: Meaningful Auditory Integration Scale

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Outcome assessments

Auditory skills are defined as the ability of sound understanding which is assessed on CAP and MAIS criteria. All children were examined by questionnaires such as the CAP and MAIS[5],[6] to measure the auditory perception development in children. Auditory perception in children using cochlear implants was studied in relation to the patient variable of radiological abnormality in temporal bone or brain (whether present/absent). If a radiological abnormality in HRCT temporal bone or MRI brain was present, then details of the radiological abnormality in cochlear implant recipient were noted down. Children, with the absence of any radiological abnormality in HRCT temporal bone or MRI brain, were chosen as control group. All children with radiological abnormality in MRI brain were referred to pediatrics neurology clinic for advanced examination. CAP and MAIS scores were calculated at 1 year after CI.

Scientific and ethical considerations

All procedures were approved by the children's parents. This study was approved by the hospital's Ethics Committee .

Statistical analysis

Relationship of the variable “radiological abnormality on HRCT temporal bone or MRI brain” to auditory perception outcome (mean CAP and MAIS scores) was analyzed 1 year postimplant using Chi-square test, paired test, and independent t-test.


  Results Top


A total of fifty children had undergone CI over 18-month period. Out of these children, 15 (30%) had the radiological abnormality in temporal bone or brain, whereas 35 children (70%) did not have the radiological abnormality. Among children with radiological abnormality in temporal bone or brain, 8 (53.3%) were male and 7 (46.7%) were female. The mean age of all participant children was 5.06 years. The mean age of case group with radiological abnormality in temporal bone or brain was 4.9 years, and the mean age of control group without the radiological abnormality was 5.1 years. Mean CAP and MAIS scores were calculated for both case and control groups at 1 year after CI [Table 3], [Table 4], [Table 5].
Table 3: The prevalence of radiological abnormality in high-resolution computed tomography temporal bone or magnetic resonance imaging brain according to gender

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Table 4: Categories of auditory perception criteria scores after 1 year postcochlear implantation in children with radiological abnormality and children without radiological abnormality in high-resolution computed tomography temporal bone or magnetic resonance imaging brain

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Table 5: Meaningful Auditory Integration Scale scores at 1 year after cochlear implantation in children with radiological abnormality and children without radiological abnormality in high-resolution computed tomography temporal bone or magnetic resonance imaging brain

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In this study, for cochlear implant recipient children without any radiological abnormality in HRCT temporal bone or MRI brain, mean CAP score was 6.37 and mean MAIS score was 35.66 at 1 year after CI [Table 6] and [Graph 1].
Table 6: Mean categories of auditory perception and Meaningful Auditory Integration Scale scores at 1 year after cochlear implantation in children with radiological abnormality and children without radiological abnormality in high-resolution computed tomography temporal bone or magnetic resonance imaging brain

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For cochlear implant recipient children with radiological abnormalities in HRCT temporal bone or MRI brain (e.g., 9 had demyelination of white matter of brain, 3 had features of mastoiditis, 1 had Mondini's dysplasia, 1 had moderate communicating hydrocephalus, and 1 had right cochlea smaller than left), the mean CAP score was 5.93 and mean MAIS score was 33.73 at 1 year after CI [Table 6], [Table 7] and [Graph 1].
Table 7: The prevalence of individual radiological abnormality in high-resolution computed tomography temporal bone or magnetic resonance imaging brain

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Hence, it was noticed that there were significantly reduced mean auditory perception outcomes (decrease of 6.9% in mean CAP and 5.4% in mean MAIS scores at 1 year after CI) in children who had radiological abnormalities in comparison to those who had no radiological abnormality on HRCT temporal bone or MRI brain (P value <0.05 (significant) for both mean CAP and mean MAIS scores)[18].


  Discussion Top


This study was performed to evaluate the effect of radiological abnormalities on HRCT temporal bone or MRI brain on auditory perception outcomes after CI in children with bilateral severe-to-profound SNHL. The effects of bilateral severe-to-profound hearing loss are widely known to be serious, especially in relation to understanding and using spoken language. Children with neurological disabilities in addition to their auditory deficit may experience further obstacles in auditory perception and then learning language. In many studies, the differences between the groups started becoming evident after a year after the CI.[7],[8] Deafness may be only one aspect of a syndrome with several symptoms that affect a child. Children with syndrome-related causes of deafness scored significantly lower than children with nonsyndromic etiologies on tests of auditory perception and speech intelligibility.

Improvement in technology and expertise has led to better auditory perception outcomes in children. In a study conducted by Eisenman et al. in 2001 and also other studies, any presence of radiological abnormality in temporal bone or brain of cochlear implant recipients would eventually result in poorer auditory perception outcomes.[9],[10] Some of the previous studies of CI in children with radiology suggestive of inner-ear abnormalities have reported inconsistent and less certain results.[10],[11],[12],[13] Many factors that further determine the results of CI in children with radiology suggestive of inner-ear abnormalities may include age at implantation, duration of deafness, mode of communication, and preoperative speech perception, thus additionally influencing the results of CI in such children.[14] One significant factor thought to affect the results of CI in children with radiology suggestive of inner-ear abnormalities is the number of spiral ganglion cells in the auditory pathway. Spiral ganglion cells are the primary neural elements in auditory stimulation.[15] Thus, many authors believe that cochlear implants may have limited benefits in patients with reduced spiral ganglion cell numbers. Inner-ear malformations are often associated with concomitant hypoplastic/compromised auditory pathway between the cochlea and the brain stem. Hence, there may be compromised response to input from the CI. Several studies have demonstrated poor CI results in patients with compromised auditory pathway.[16],[17] In this study also, we have found significant reduction in mean auditory perception outcomes (decrease of 6.9% in mean CAP and 5.4% in mean MAIS scores at 1 year after CI) in children who had radiological abnormalities in comparison to those who had no radiological abnormality on HRCT temporal bone or MRI brain. However, even the children with radiological abnormality in temporal bone or brain showed substantial improvement in auditory perception (mean CAP score was 5.93 and mean MAIS score was 33.73) at 1 year after CI albeit less than the control group without any radiological abnormality in temporal bone or brain (mean CAP score was 6.37 and mean MAIS score was 35.66) if we assume their mean CAP and MAIS scores before the CI surgery to be near “0.”


  Conclusion Top


There are various international studies on various patient and surgical factors affecting auditory perception outcomes after cochlear implant surgery.[3],[4] However, adequate Indian data are not available on the effects of radiological abnormalities in temporal bone and brain on auditory perception outcomes in cochlear implant recipient children. This study may provide useful information for counseling Indian families considering CI for their child in the presence of a radiological abnormality in temporal bone or brain.

Hence, it is safe to conclude that, in Indian cochlear implant scenario, knowledge of the individual factor of “Presence or absence of a radiological abnormality on HRCT temporal bone or MRI brain” can provide reasonable help in predicting the auditory perception and hence spoken language outcomes for individual implant candidates prior to the CI surgery. However, the accuracy of such predictions is limited, and they should only be used as a guide toward predicting auditory perception outcomes.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Miyamoto RT, Osberger MJ, Todd SL, Robbins AM, Stroer BS, Zimmerman-Phillips S, et al. Variables affecting implant performance in children. Laryngoscope 1994;104:1120-4.  Back to cited text no. 1
    
2.
Dowell RC, Cowan RS. Evaluation of benefit: Infants and children. In: Clark GM, editor. Cochlear Implantation for Infants and Children – Advances. San Diego, CA: Singular Publishing Group; 1997. p. 205-22.  Back to cited text no. 2
    
3.
Osberger MJ, Fisher L, Zimmerman-Phillips S, Geier L, Barker MJ. Speech recognition performance of older children with cochlear implants. Am J Otol 1998;19:152-7.  Back to cited text no. 3
    
4.
Tye-Murray N, Spencer L, Woodworth GG. Acquisition of speech by children who have prolonged cochlear implant experience. J Speech Hear Res 1995;38:327-37.  Back to cited text no. 4
    
5.
Archbold S, Lutman ME, Marshall DH. Categories of auditory performance. Ann Otol Rhinol Laryngol Suppl 1995;166:312-4.  Back to cited text no. 5
    
6.
Zimmerman-Phillips S, Robbins AM, Osberger MJ. Infant-Toddler Meaningful Auditory Integration Score. Sylmar, Calif: Advanced Bionics Corp; 2001.  Back to cited text no. 6
    
7.
Rajput K, Brown T, Bamiou DE. Aetiology of hearing loss and other related factors versus language outcome after cochlear implantation in children. Int J Pediatr Otorhinolaryngol 2003;67:497-504.  Back to cited text no. 7
    
8.
Quittner AL, Steck JT. Predictors of cochlear implant use in children. Am J Otol 1991;12 Suppl: 89-94.  Back to cited text no. 8
    
9.
Susan B, Waltzman J, Thomas R. Cochlear Implants. 2nd ed. New York: Thieme Medical Publishers; 2006. p. 33-151.  Back to cited text no. 9
    
10.
Eisenman DJ, Ashbaugh C, Zwolan TA, Arts HA, Telian SA. Implantation of the malformed cochlea. Otol Neurotol 2001;22:834-41.  Back to cited text no. 10
    
11.
Loundon N, Rouillon I, Munier N, Marlin S, Roger G, Garabedian EN, et al. Cochlear implantation in children with internal ear malformations. Otol Neurotol 2005;26:668-73.  Back to cited text no. 11
    
12.
Woolley AL, Jenison V, Stroer BS, Lusk RP, Bahadori RS, Wippold FJ 2nd, et al. Cochlear implantation in children with inner ear malformations. Ann Otol Rhinol Laryngol 1998;107:492-500.  Back to cited text no. 12
    
13.
Luntz M, Balkany T, Hodges AV, Telischi FF. Cochlear implants in children with congenital inner ear malformations. Arch Otolaryngol Head Neck Surg 1997;123:974-7.  Back to cited text no. 13
    
14.
Svirsky MA, Robbins AM, Kirk KI, Pisoni DB, Miyamoto RT. Language development in profoundly deaf children with cochlear implants. Psychol Sci 2000;11:153-8.  Back to cited text no. 14
    
15.
Clopton BM, Spelman FA, Miller JM. Estimates of essential neural elements for stimulation through a cochlear prosthesis. Ann Otol Rhinol Laryngol Suppl 1980;89:5-7.  Back to cited text no. 15
    
16.
Bradley J, Beale T, Graham J, Bell M. Variable long-term outcomes from cochlear implantation in children with hypoplastic auditory nerves. Cochlear Implants Int 2008;9:34-60.  Back to cited text no. 16
    
17.
Kutz JW Jr., Lee KH, Isaacson B, Booth TN, Sweeney MH, Roland PS, et al. Cochlear implantation in children with cochlear nerve absence or deficiency. Otol Neurotol 2011;32:956-61.  Back to cited text no. 17
    
18.
Fisher RA. Nig J Paediatr. London: Oliver and Boyd. Statistical methods for research workers; 1950. p. 80.  Back to cited text no. 18
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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