- Email: [email protected]
Impact of cochlear abnormalities on hearing outcomes for children with cochlear implants
Journal Pre-proof Impact of cochlear abnormalities on hearing outcomes for children with cochlear implants
Evette Ronner, Razan Basonbul, Rupal Bhakta, Leila Mankarious, Daniel J. Lee, Michael S. Cohen PII:
S0196-0709(19)31034-8
DOI:
https://doi.org/10.1016/j.amjoto.2019.102372
Reference:
YAJOT 102372
To appear in:
American Journal of Otolaryngology--Head and Neck Medicine and Surgery
Received date:
4 December 2019
Please cite this article as: E. Ronner, R. Basonbul, R. Bhakta, et al., Impact of cochlear abnormalities on hearing outcomes for children with cochlear implants, American Journal of Otolaryngology--Head and Neck Medicine and Surgery(2018), https://doi.org/10.1016/ j.amjoto.2019.102372
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2018 Published by Elsevier.
Journal Pre-proof
Impact of cochlear abnormalities on hearing outcomes for children with cochlear implants
Evette Ronner, BA1; Razan Basonbul, MBBS, MPH2; Rupal Bhakta, Au.D., CCC-A1; Leila Mankarious, MD1,3; Daniel J. Lee, MD1,3, FACS; Michael S. Cohen, MD1,3
Department of Otolaryngology, Faculty of Medicine, King Abdulaziz University, Rabigh, Saudi Arabia
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Department of Otolaryngology, Harvard Medical School, Boston, MA
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Corresponding Author:
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2
Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, MA
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1
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Michael S. Cohen, M.D.
Massachusetts Eye and Ear Infirmary 243 Charles St. | Boston, MA 02114 Tel: 617-391-5998
Fax: 617-573-3012
Email: [email protected]
Journal Pre-proof Abstract OBJECTIVE: Evaluate the impact of cochlear anomalies on hearing outcomes for pediatric patients with cochlear implants. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary care center. SUBJECTS AND METHODS: Charts were retrospectively reviewed for cases where pediatric
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cochlear implant surgery was performed between 2002 to 2018 at a single, tertiary care
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institution. Patients were divided into groups based on the presence or absence of radiological
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cochlear abnormalities, which were further classified as low or high risk anomalies. Hearing
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outcomes were evaluated by measuring pure tone averages and word recognition scores preoperatively, 3 and 12 months postoperatively, in addition to the most recent test results.
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RESULTS: There were 154 ears implanted in our cohort of 100 patients. 107 ears had normal
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cochlear anatomy, 31 had low risk, and 16 had high risk abnormalities. The most common modality of preoperative imaging was CT scan. Postoperative mean pure tone average (PTA)
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was significantly higher in patients with inner ear anomalies compared to those with normal
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anatomy. No significant difference in PTA was noted between low versus high risk patients. <50% of patients had word recognition scores available within the first year following surgery. CONCLUSION: Abnormalities of the inner ear significantly influenced hearing outcomes over time following cochlear implant surgery when compared to pediatric patients with normal anatomy. Obtaining hearing testing can be difficult in very young children and therefore future studies are warranted to further investigate the impact that cochlear abnormalities may have on hearing outcomes following cochlear implant surgery. KEY WORDS: Hearing loss, cochlear implant, inner ear abnormalities, cochlear anomaly
Journal Pre-proof 1. Introduction Hearing loss affects 1-3 infants per 1,000 births in the United States [1]. Since the introduction of universal newborn hearing screening, children with sensorineural hearing loss (SNHL) are often identified at birth [2]. There are a variety of developmental abnormalities which can cause congenital SNHL, which include malformations of the cochlea, cochlear nerve, semicircular canals, and vestibular aqueducts. These anomalies are often identified on diagnostic
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imaging, such as CT or MRI, and are identified in approximately 40% of children with SNHL
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[3]. Identifying hearing loss and determining its underlying cause at a young age is important, as
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this can guide treatment plans which can ultimately impact speech and language outcomes.
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Cochlear implantation is a surgical procedure which can partially restore hearing for patients with SNHL. The procedure was first performed in 1961 and over time has become a
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standard of care treatment for auditory rehabilitation in pediatric patients with severe-to profound
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SNHL [4]. The presence of a cochlea and cochlear nerve are considered necessary for cochlear implantation; however, other structural abnormalities of the inner ear are not necessarily
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contraindications for implantation [5,6]. Therefore, among children who undergo cochlear
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implant surgery, some have cochlear anomalies identified on imaging and others do not. It is not clear whether the presence of less severe abnormalities impacts surgical or hearing outcomes. Some studies have shown that children with abnormal anatomy experience poorer outcomes, such as poorer hearing thresholds and word recognition scores, and increased rates of complications compared to those with normal anatomy [7, 8]. Other studies have shown no difference in postoperative outcomes between these two groups [9,10]. However, many of these studies’ sample sizes are small and there is wide variation in the methods utilized to evaluate hearing outcomes [11].
Journal Pre-proof The purpose of this study is to retrospectively evaluate whether inner ear anomalies impact hearing outcomes for children with SNHL who underwent cochlear implant surgery. Through a retrospective analysis at a tertiary care institution, we hope that a larger sample size will allow for a better understanding on how inner ear anomalies may impact postoperative outcomes.
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2. Methods
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2.1 Study population
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This study was approved by the Partners Institutional Review Board (IRB) (protocol
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#2019P000115).
A retrospective chart review was performed for children who underwent cochlear implant
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surgery at our institution between December 1st, 2002 and December 1st, 2018. Patients were
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included if they were under the age of 18 and had a cochlear implant surgery performed between 2002 and 2018. Patients were excluded if the surgery was performed outside of our institution, or
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if the patient had no imaging or audiology data available.
2.2 Data collection
The following data were collected for each available chart: gender, age at the time of surgery, hearing loss laterality and severity, ear(s) implanted, manufacturer of implant, type and results of preoperative imaging, comorbidities, postoperative complications, and hearing outcomes, which included pure tone averages and word recognition scores at 0, 3, and 12 months postoperative as well as the most recent available hearing test results. The length of audiology follow up was defined as the amount of time between surgery and most recent audiogram. CT
Journal Pre-proof and MRI images were reviewed to determine whether patients had normal or abnormal inner ear anatomy. Anatomical abnormalities were further classified as low risk or high risk. Low risk abnormalities included enlarged vestibular aqueduct (EVA), lateral semicircular canal abnormalities, incomplete partition type 2 (IP-2), wide internal auditory canal, whereas high risk abnormalities included cochlear hypoplasia and dysplasia, cochlear aperture abnormalities, common cavity deformity and cochlear nerve deficiency.
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Pure tone average (PTA) was calculated by taking the average of the hearing threshold
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levels at 500, 1000, 2000, and 3000 Hz. If no data was collected at 3000 Hz, then the average of
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2000 and 4000 Hz was calculated instead. A minimum of two data points was required to calculate PTA. Word recognition scores (WRS) were measured using a variety of speech tests
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depending on the child’s age. These included the Early Speech Perception (ESP), Word
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Intelligibility by Picture Identification (WIPI), Consonant Nucleus Consonant (CNC) tests.
WRS analysis.
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2.3 Statistical Analysis
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Seven cases did not have ear-specific word recognition testing available and were excluded from
Statistical analysis was performed using STATA (StataCorp. 2013. Stata Statistical Software: Release 13. College Station, TX: StataCorp LP.). Chi-square or Fisher’s exact test was used to compare categorical data between the normal, low and high risk anatomy groups. The nonparametric Kruskal-Wallis test was used when means from continuous data were compared since data were assumed to not have a normal distribution. Independent t-tests were used to compare PTA between groups at preoperative, 3 and 12 months postoperative. A p-value less than 0.05 was considered statistically significant.
Journal Pre-proof
3. Results In our cohort, 154 ears from 100 patients were included. Patient demographics are summarized in Table 1. One hundred and seven ears had normal inner ear anatomy, 31 had low risk anomalies, and 16 had high risk anomalies. Seventy left ears and 84 right ears were implanted. Patients with low risk anatomy were significantly older at the time of surgery
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compared to those with normal or high risk anatomy (p=0.01). The most common type of
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preoperative imaging was CT; 70 cases had a CT scan only, 34 had an MRI only, and 50 had
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both a CT and MRI prior to surgery. There were 11 cases of congenital cytomegalovirus. The
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device manufacturer was noted for 129 cases and included 75 implants manufactured by Advanced Bionics (Valencia, CA, USA), 42 from Cochlear Corporation (Australia; Centennial,
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CO, USA), and 12 from MED-EL (Austria; Durham, NC, USA). Several complications were
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noted, including device failure in 3 cases, electrode misplacement in 2 cases, and postoperative vertigo in 2 cases. There was a significant difference in mean length of audiology follow up
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(p=0.01), which was an average of 40, 20, and 50 months for patients with normal, low, and high
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risk anatomy, respectively.
Among the 47 ears with abnormal anatomy, a variety of anomalies were noted. The most common finding was enlarged vestibular aqueduct in 22 ears (Table 2). Abnormalities of the lateral semicircular canal and IP-II were noted for 15 and 12 ears, respectively. Eight cases were noted for cochlear nerve deficiency and 6 for cochlear hypoplasia. There were several cases each of wide internal auditory canal, cochlear dysplasia, cochlear aperture abnormalities, and common cavity deformity.
Journal Pre-proof Audiologic data was not available for all patients at each timepoint. Table 3 displays the number of patients that had pure tone audiometry and word recognition testing before surgery, as well as 3 and 12 months after surgery. The majority of patients had pure tone audiometry results available. When comparing patients with and without cochlear abnormalities, a similar percentage had pure tone audiometry results available at each time point. However, few patients had speech testing prior to surgery. Only 12%, 19%, and 13% of patients with normal, low, and
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high risk anatomy, respectively, had available results from preoperative speech testing. WRS
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were most likely to be obtained at postoperative month 12, though the percentage of patients
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with available test results was below 50% for all groups.
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Preoperative pure tone average measurements were similar for patients with and without cochlear anomalies (Figure 1). At postoperative months 3 and 12, mean PTA was significantly
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higher in patients with inner ear anomalies compared to those with normal anatomy. No
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significant difference in postoperative PTA was observed between patients with low compared to high risk anatomy. Figure 2 displays PTA and WRS scores for patients with normal, low and
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high risk anatomy, before and after surgery. Following surgery, PTA typically improved to 40 db
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or less and WRS to 70% or greater for all groups.
Journal Pre-proof 4. Discussion This study demonstrates that all patients with either minor or major inner ear abnormalities showed improvement in hearing following surgery. The data presented in this study reaffirms that patients with inner anomalies may be suitable candidates for cochlear implantation, though postoperative hearing outcomes may be poorer for children with inner ear anomalies compared to those with normal anatomy. Importantly, the presence of a low versus
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high risk anomaly did not significantly impact postoperative PTA in this study, though this
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distinction may be limited by relatively small sample size. Also, because few complications were
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noted in either group, a conclusion cannot be made regarding whether children with inner ear
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anomalies are at increased risk of experiencing surgical complications. In our cohort, patients with low risk anatomy were significantly older at the time of
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surgery compared to patients with normal or high risk anatomy. The most common low risk
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abnormality was EVA, an anomaly which can be associated with progressive hearing loss [12]. Therefore, these children often become audiologic candidates for cochlear implantation later in
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life. It is possible that this difference in age and indeed the process of determining when to
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implant a child with progressive hearing loss could influence the post cochlear implant hearing outcomes for this group. Close monitoring of hearing in patients with EVA is important to ensure that these children can be identified as candidates for implantation as early as possible to optimize hearing outcomes. Despite some variation in the literature, our study is similar to other previously published studies. Our findings are consistent with a study by Isaiah et al, which showed significant differences in hearing outcomes following surgery for children with cochlear anomalies [7]. One exception noted by Isaiah et al. is that children with EVA had results comparable to children
Journal Pre-proof with normal anatomy, which differs from our findings in the low risk anatomy group. However, this may be because their primary outcome was speech testing, whereas our study focused on PTA due to the limited number of preoperative WRS data available. Chadha et al. reported that children with cochlear abnormalities were not at increased risk for surgical complications or poorer hearing outcomes following cochlear implant surgery, though children with EVA were not included in this cohort [10]. In a study by Bille et al., cochlear abnormalities did not
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significantly impact long term category of auditory performance (CAP) and speech intelligibility
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rating (SIR) scores [9]; however, since those subjects underwent implantation between 2003-
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2007, it is possible that the clinical management of these cases have changed over time which
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could influence hearing outcomes in this population.
This study highlights the challenges of obtaining consistent audiologic data in young
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children to evaluate changes in hearing following cochlear implant surgery. Because many
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children at our institution were implanted at a very young age, speech testing is not possible before and immediately after surgery since these patients may not have developed speech prior to
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surgery. Similarly, in these young patients, threshold testing is sometimes incomplete and may
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only contain a single data point. This challenge hinders our analysis for this young group. Future prospective studies may help to standardize the collection of audiologic data. A universal standard test battery for pediatric cochlear implant patients would be a welcome addition to the field. There are limitations to our study. Audiologic data was not available for some patients at specific timepoints. This was most notable for word recognition scores, which were often not measured around the time of surgery because most patients were implanted at a very young age. For some hearing tests, only sound field test results were available, therefore making it
Journal Pre-proof challenging to evaluate changes in hearing specific to the surgical ear. We are unable to conclude whether specific abnormalities within each subgroup are associated with poorer hearing outcomes compared to others. A few subjects had comorbidities, such as developmental delay and autism, which could interfere with the results obtained during their audiologic testing. Because our institution serves many international families, postoperative follow up was often limited for these patients. Additionally, it is possible that other factors, such as socioeconomic
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status or school setting, could influence a patient’s hearing development.
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5. Conclusion
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In conclusion, this study suggests that the presence of inner ear abnormalities impacts hearing outcomes following cochlear implant surgery. The severity of such anomalies did not
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significantly affect postoperative hearing outcomes in this population. Given the inconsistent
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findings in the literature, future studies should consider a prospective, multisite approach with
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standardized testing and a larger sample size.
Journal Pre-proof 6. Acknowledgements
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Ms. Ronner was involved in execution of the study, acquisition of data, analysis and interpretation of data, drafting the article, and final approval of the manuscript as submitted. Dr. Basonbul assisted in acquisition of data, analysis and interpretation of data, and final approval of the manuscript as submitted. Dr. Bhakta assisted in execution of the study and final approval of the manuscript as submitted. I would also like to thank Dr. Kevin Franck for critical review of this manuscript. Drs. Mankarious, Lee, and Cohen were involved in planning and execution of the study, as well as critical review and revision of the manuscript and approval of the final manuscript as submitted.
Journal Pre-proof 7. References 1. Hawley KA, Goldberg DM, Anne S. Utility of a multidisciplinary approach to pediatric hearing loss. Am J Otolaryngol. 2017;38(5):547-550. doi:10.1016/j.amjoto.2017.05.008 2. Shulman S, Besculides M, Saltzman A, Ireys H, White K, Forsman I. Evaluation of the universal newborn hearing screening and intervention program. Pediatrics. 2010;Aug;126 Suppl 1:S19-27. doi: 10.1542/peds.2010-0354F. 3. Wentland CJ, Ronner EA, Basonbul RA, Pinnapureddy S, Mankarious L, Keamy D, Lee DJ, Cohen MS. Utilization of diagnostic testing for pediatric sensorineural hearing loss.
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Int J Pediatr Otorhinolaryngol. 2018 Aug;111:26-31. doi: 10.1016/j.ijporl.2018.05.024. 4. Mudry A, Mills, M. The Early History of the Cochlear Implant: A Retrospective. JAMA
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Otolaryngol Head Neck Surg. 2013 May;139(5):446-53. doi: 10.1001/jamaoto.2013.293. 5. Daya H, Figueirido JC, Gordon KA, Twitchell K, Gysin C, Papsin BC. The role of a
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graded profile analysis in determining candidacy and outcome for cochlear implantation in children. Int J Pediatr Otorhinolaryngol. 1999;49(2), 135-142.
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6. Young, JY, Ryan ME, Young NM. (2014). Preoperative imaging of sensorineural hearing loss in pediatric candidates for cochlear implantation. Radiographics. 2014 Sep-
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Oct;34(5):E133-49. doi: 10.1148/rg.345130083. 7. Isaiah A, Lee A, Lenes-Voit F, Sweeney M, Kutz W, Isaacson B, Roland P, Lee, KH.
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Clinical outcomes following cochlear implantation in children with inner ear anomalies. Int J Pediatr Otorhinolaryngol. 2017 Feb;93:1-6. doi: 10.1016/j.ijporl.2016.12.001.
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8. Papsin, B. Cochlear Implantation in Children With Anomalous Cochleovestibular Anatomy. Laryngoscope. 2005 Jan;115(S106):1-26
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9. Bille J., Fink-Jensen V, Ovesen T. (2015). Outcome of cochlear implantation in children with cochlear malformations. Eur Arch Otorhinolaryngol. 2015 Mar;272(3):583-9. doi: 10.1007/s00405-014-2883-z. 10. Chadha N, James A, Gordon K, Blaser S, Papsin, B. (2009). Bilateral Cochlear Implantation in Children With Anomalous Cochleovestibular Anatomy. Arch Otolaryngol Head Neck Surg. 2009 Sep;135(9):903-9. doi: 10.1001/archoto.2009.120. 11. Pakdaman MN1, Herrmann BS, Curtin HD, Van Beek-King J, Lee DJ. Cochlear implantation in children with anomalous cochleovestibular anatomy: a systematic review. Otolaryngol Head Neck Surg. 2012 Feb;146(2):180-90. doi: 10.1177/0194599811429244. 12. Madden C, Halsted M, Benton C, Greinwald J, Choo D. (2003). Enlarged vestibular aqueduct syndrome in the pediatric population. Otol Neurotol. 2003 Jul;24(4):625-32.
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Table 1. Patient Demographics distributed by number of ears
Total Patients
Normal anatomy N (%)
Low risk anatomy N (%)
High risk anatomy N (%)
p-value**
107 (100)
31 (100)
16 (100)
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55 (51) 52 (49)
18 (58) 13 (42)
7 (44) 9 (56)
Ear implanted Left Right
4.4 (1-12)
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Preoperative comorbidities Congenital CMV Developmental delay Connexin 26 mutation Pendred syndrome Mitochondrial disease Meningitis CHARGE syndrome Autism Seizure disorder Cleft lip and palate Malaria Cerebral palsy Paroxysmal tonic upgaze Other genetic abnormality None
12 (39) 19 (61)
0.01 2.8 (0-15) 0.52 9 (56) 7 (44) 0.21
44 (41) 30 (28) 33 (31)
19 (61) 3 (10) 9 (29)
7 (44) 1 (6) 8 (50)
10 (9) 5 (5) 3 (3) 0 (0) 1 (1) 0 (0) 0 (0) 3 (3) 2 (2) 1 (1) 2 (2) 1 (1) 0 (0) 4 (4) 72 (67)
1 (3) 1 (3) 0 (0) 3 (10) 0 (0) 0 (0) 0 (0) 1 (3) 0 (0) 0 (0) 0 (0) 0 (0) 1 (3) 2 (6) 16 (52)
0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 2 (12) 2 (12) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 1 (6) 11 (69)
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Preoperative imaging CT only MRI only CT and MRI
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49 (46) 58 (54)
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2.8 (0-15)
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Mean age at surgery in years (range)
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0.64
Gender Male Female
0.01
Journal Pre-proof CI* manufacturer Advanced Bionics Cochlear MED-EL Not specified
0.01 52 (49) 31 (29) 11 (10) 13 (12)
14 (45) 4 (13) 1 (3) 12 (39)
9 (56) 7 (44) 0 (0) 0 (0) 0.64
Postop complications Device failure Electrode misplacement Vertigo Mean length of audiology follow up in months (range)
0 (0) 0 (0) 2 (6)
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3 (3) 2 (2) 0 (0)
40 (0-113)
20 (0-56)
0 (0) 0 (0) 0 (0)
55 (5-113)
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*Note: CI = cochlear implant ** Chi square or Fisher’s exact test *** Kruskal-wallis test
0.01 ***
Journal Pre-proof Table 2. Summary of Anomalies per ear N=154 ears
No anomalies
107
Low risk anomalies Enlarged vestibular aqueduct Lateral semicircular canal abnormalities IP-II Wide internal auditory canal
22 15 12 1
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Anomalies
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High risk anomalies Cochlear nerve deficiency Cochlear hypoplasia Cochlear dysplasia Cochlear aperture abnormalities Common cavity deformity
8 6 3 2 2
Journal Pre-proof Table 3. Number of patients with available hearing test results over time Preop N (%)
3 months postop N (%)
12 months postop N (%)
95 (89)
83 (78)
75 (70)
Low risk anatomy (N = 31)
25 (81)
23 (74)
18 (58)
High risk anatomy ( N = 16)
15 (93)
11 (69)
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Normal anatomy (N = 107 ears)
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Pure tone audiometry
13 (81)
13 (12)
Low risk anatomy (N = 31) High risk anatomy ( N = 16)
21 (20)
6 (19)
11 (35)
14 (45)
3 (19)
5 (31)
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13 (12)
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Normal anatomy (N = 107 ears)
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Word recognition scores
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2 (13)
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Figure 1. Mean pure tone average (PTA) following cochlear implant surgery. Note: PTA = pure tone average. All PTA values are reported in decibels. *p<0.05
Journal Pre-proof NORMAL ANATOMY Pre-treatment (n=12 ears)
Post-treatment (n=53 ears)
WRS in affected ear (%)
WRS in affected ear (%)
PTA 100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
PTA 100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
0-10
0-10
11-20
11-20
21-30
21-30
1 12
12
7
31-40
31-40
1
4
8
41-50
1
41-50
1
51-60
1
1
1
1
71-80
1
81-90
2 1
81-90
1
>91
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>91
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61-70
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71-80
1
51-60
1
61-70
2
LOW RISK ANATOMY
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Pre-treatment (n=5 ears)
Post-treatment (n=20 ears)
WRS in affected ear (%) PTA
100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
31-40 41-50
11-20
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11-20
PTA 100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0 0-10
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0-10
21-30
WRS in affected ear (%)
21-30
1
31-40
1
51-60
61-70
61-70
71-80
71-80
>91
1 1
2 4
2
81-90 >91
2 1
41-50
51-60
81-90
4
1
1
1
Journal Pre-proof HIGH RISK ANATOMY Pre-treatment (n=2 ear)
Post-treatment (n=11 ears)
WRS in affected ear (%) PTA
WRS in affected ear (%) PTA 100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
0-10
0-10
11-20
11-20
21-30
21-30
3
31-40
31-40
2
41-50
41-50
51-60
51-60
61-70
61-70
71-80
71-80
81-90
81-90
1
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1
1
2
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1
>91
1
>91
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Figure 2. Preoperative and postoperative hearing testing for pediatric patients who underwent cochlear implant surgery with either normal, low risk, or high risk inner ear anatomy. Note: PTA = pure tone average. WRS = word recognition score. Post-treatment values represent the most recent testing obtained as of April 2019.
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Evette Ronner, Razan Basonbul, Rupal Bhakta, Leila Mankarious, Daniel J. Lee, Michael S. Cohen PII:
S0196-0709(19)31034-8
DOI:
https://doi.org/10.1016/j.amjoto.2019.102372
Reference:
YAJOT 102372
To appear in:
American Journal of Otolaryngology--Head and Neck Medicine and Surgery
Received date:
4 December 2019
Please cite this article as: E. Ronner, R. Basonbul, R. Bhakta, et al., Impact of cochlear abnormalities on hearing outcomes for children with cochlear implants, American Journal of Otolaryngology--Head and Neck Medicine and Surgery(2018), https://doi.org/10.1016/ j.amjoto.2019.102372
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2018 Published by Elsevier.
Journal Pre-proof
Impact of cochlear abnormalities on hearing outcomes for children with cochlear implants
Evette Ronner, BA1; Razan Basonbul, MBBS, MPH2; Rupal Bhakta, Au.D., CCC-A1; Leila Mankarious, MD1,3; Daniel J. Lee, MD1,3, FACS; Michael S. Cohen, MD1,3
Department of Otolaryngology, Faculty of Medicine, King Abdulaziz University, Rabigh, Saudi Arabia
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Department of Otolaryngology, Harvard Medical School, Boston, MA
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Corresponding Author:
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3
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2
Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, MA
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1
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Michael S. Cohen, M.D.
Massachusetts Eye and Ear Infirmary 243 Charles St. | Boston, MA 02114 Tel: 617-391-5998
Fax: 617-573-3012
Email: [email protected]
Journal Pre-proof Abstract OBJECTIVE: Evaluate the impact of cochlear anomalies on hearing outcomes for pediatric patients with cochlear implants. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary care center. SUBJECTS AND METHODS: Charts were retrospectively reviewed for cases where pediatric
of
cochlear implant surgery was performed between 2002 to 2018 at a single, tertiary care
ro
institution. Patients were divided into groups based on the presence or absence of radiological
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cochlear abnormalities, which were further classified as low or high risk anomalies. Hearing
re
outcomes were evaluated by measuring pure tone averages and word recognition scores preoperatively, 3 and 12 months postoperatively, in addition to the most recent test results.
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RESULTS: There were 154 ears implanted in our cohort of 100 patients. 107 ears had normal
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cochlear anatomy, 31 had low risk, and 16 had high risk abnormalities. The most common modality of preoperative imaging was CT scan. Postoperative mean pure tone average (PTA)
ur
was significantly higher in patients with inner ear anomalies compared to those with normal
Jo
anatomy. No significant difference in PTA was noted between low versus high risk patients. <50% of patients had word recognition scores available within the first year following surgery. CONCLUSION: Abnormalities of the inner ear significantly influenced hearing outcomes over time following cochlear implant surgery when compared to pediatric patients with normal anatomy. Obtaining hearing testing can be difficult in very young children and therefore future studies are warranted to further investigate the impact that cochlear abnormalities may have on hearing outcomes following cochlear implant surgery. KEY WORDS: Hearing loss, cochlear implant, inner ear abnormalities, cochlear anomaly
Journal Pre-proof 1. Introduction Hearing loss affects 1-3 infants per 1,000 births in the United States [1]. Since the introduction of universal newborn hearing screening, children with sensorineural hearing loss (SNHL) are often identified at birth [2]. There are a variety of developmental abnormalities which can cause congenital SNHL, which include malformations of the cochlea, cochlear nerve, semicircular canals, and vestibular aqueducts. These anomalies are often identified on diagnostic
of
imaging, such as CT or MRI, and are identified in approximately 40% of children with SNHL
ro
[3]. Identifying hearing loss and determining its underlying cause at a young age is important, as
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this can guide treatment plans which can ultimately impact speech and language outcomes.
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Cochlear implantation is a surgical procedure which can partially restore hearing for patients with SNHL. The procedure was first performed in 1961 and over time has become a
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standard of care treatment for auditory rehabilitation in pediatric patients with severe-to profound
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SNHL [4]. The presence of a cochlea and cochlear nerve are considered necessary for cochlear implantation; however, other structural abnormalities of the inner ear are not necessarily
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contraindications for implantation [5,6]. Therefore, among children who undergo cochlear
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implant surgery, some have cochlear anomalies identified on imaging and others do not. It is not clear whether the presence of less severe abnormalities impacts surgical or hearing outcomes. Some studies have shown that children with abnormal anatomy experience poorer outcomes, such as poorer hearing thresholds and word recognition scores, and increased rates of complications compared to those with normal anatomy [7, 8]. Other studies have shown no difference in postoperative outcomes between these two groups [9,10]. However, many of these studies’ sample sizes are small and there is wide variation in the methods utilized to evaluate hearing outcomes [11].
Journal Pre-proof The purpose of this study is to retrospectively evaluate whether inner ear anomalies impact hearing outcomes for children with SNHL who underwent cochlear implant surgery. Through a retrospective analysis at a tertiary care institution, we hope that a larger sample size will allow for a better understanding on how inner ear anomalies may impact postoperative outcomes.
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2. Methods
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2.1 Study population
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This study was approved by the Partners Institutional Review Board (IRB) (protocol
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#2019P000115).
A retrospective chart review was performed for children who underwent cochlear implant
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surgery at our institution between December 1st, 2002 and December 1st, 2018. Patients were
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included if they were under the age of 18 and had a cochlear implant surgery performed between 2002 and 2018. Patients were excluded if the surgery was performed outside of our institution, or
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if the patient had no imaging or audiology data available.
2.2 Data collection
The following data were collected for each available chart: gender, age at the time of surgery, hearing loss laterality and severity, ear(s) implanted, manufacturer of implant, type and results of preoperative imaging, comorbidities, postoperative complications, and hearing outcomes, which included pure tone averages and word recognition scores at 0, 3, and 12 months postoperative as well as the most recent available hearing test results. The length of audiology follow up was defined as the amount of time between surgery and most recent audiogram. CT
Journal Pre-proof and MRI images were reviewed to determine whether patients had normal or abnormal inner ear anatomy. Anatomical abnormalities were further classified as low risk or high risk. Low risk abnormalities included enlarged vestibular aqueduct (EVA), lateral semicircular canal abnormalities, incomplete partition type 2 (IP-2), wide internal auditory canal, whereas high risk abnormalities included cochlear hypoplasia and dysplasia, cochlear aperture abnormalities, common cavity deformity and cochlear nerve deficiency.
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Pure tone average (PTA) was calculated by taking the average of the hearing threshold
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levels at 500, 1000, 2000, and 3000 Hz. If no data was collected at 3000 Hz, then the average of
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2000 and 4000 Hz was calculated instead. A minimum of two data points was required to calculate PTA. Word recognition scores (WRS) were measured using a variety of speech tests
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depending on the child’s age. These included the Early Speech Perception (ESP), Word
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Intelligibility by Picture Identification (WIPI), Consonant Nucleus Consonant (CNC) tests.
WRS analysis.
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2.3 Statistical Analysis
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Seven cases did not have ear-specific word recognition testing available and were excluded from
Statistical analysis was performed using STATA (StataCorp. 2013. Stata Statistical Software: Release 13. College Station, TX: StataCorp LP.). Chi-square or Fisher’s exact test was used to compare categorical data between the normal, low and high risk anatomy groups. The nonparametric Kruskal-Wallis test was used when means from continuous data were compared since data were assumed to not have a normal distribution. Independent t-tests were used to compare PTA between groups at preoperative, 3 and 12 months postoperative. A p-value less than 0.05 was considered statistically significant.
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3. Results In our cohort, 154 ears from 100 patients were included. Patient demographics are summarized in Table 1. One hundred and seven ears had normal inner ear anatomy, 31 had low risk anomalies, and 16 had high risk anomalies. Seventy left ears and 84 right ears were implanted. Patients with low risk anatomy were significantly older at the time of surgery
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compared to those with normal or high risk anatomy (p=0.01). The most common type of
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preoperative imaging was CT; 70 cases had a CT scan only, 34 had an MRI only, and 50 had
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both a CT and MRI prior to surgery. There were 11 cases of congenital cytomegalovirus. The
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device manufacturer was noted for 129 cases and included 75 implants manufactured by Advanced Bionics (Valencia, CA, USA), 42 from Cochlear Corporation (Australia; Centennial,
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CO, USA), and 12 from MED-EL (Austria; Durham, NC, USA). Several complications were
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noted, including device failure in 3 cases, electrode misplacement in 2 cases, and postoperative vertigo in 2 cases. There was a significant difference in mean length of audiology follow up
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(p=0.01), which was an average of 40, 20, and 50 months for patients with normal, low, and high
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risk anatomy, respectively.
Among the 47 ears with abnormal anatomy, a variety of anomalies were noted. The most common finding was enlarged vestibular aqueduct in 22 ears (Table 2). Abnormalities of the lateral semicircular canal and IP-II were noted for 15 and 12 ears, respectively. Eight cases were noted for cochlear nerve deficiency and 6 for cochlear hypoplasia. There were several cases each of wide internal auditory canal, cochlear dysplasia, cochlear aperture abnormalities, and common cavity deformity.
Journal Pre-proof Audiologic data was not available for all patients at each timepoint. Table 3 displays the number of patients that had pure tone audiometry and word recognition testing before surgery, as well as 3 and 12 months after surgery. The majority of patients had pure tone audiometry results available. When comparing patients with and without cochlear abnormalities, a similar percentage had pure tone audiometry results available at each time point. However, few patients had speech testing prior to surgery. Only 12%, 19%, and 13% of patients with normal, low, and
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high risk anatomy, respectively, had available results from preoperative speech testing. WRS
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were most likely to be obtained at postoperative month 12, though the percentage of patients
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with available test results was below 50% for all groups.
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Preoperative pure tone average measurements were similar for patients with and without cochlear anomalies (Figure 1). At postoperative months 3 and 12, mean PTA was significantly
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higher in patients with inner ear anomalies compared to those with normal anatomy. No
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significant difference in postoperative PTA was observed between patients with low compared to high risk anatomy. Figure 2 displays PTA and WRS scores for patients with normal, low and
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high risk anatomy, before and after surgery. Following surgery, PTA typically improved to 40 db
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or less and WRS to 70% or greater for all groups.
Journal Pre-proof 4. Discussion This study demonstrates that all patients with either minor or major inner ear abnormalities showed improvement in hearing following surgery. The data presented in this study reaffirms that patients with inner anomalies may be suitable candidates for cochlear implantation, though postoperative hearing outcomes may be poorer for children with inner ear anomalies compared to those with normal anatomy. Importantly, the presence of a low versus
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high risk anomaly did not significantly impact postoperative PTA in this study, though this
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distinction may be limited by relatively small sample size. Also, because few complications were
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noted in either group, a conclusion cannot be made regarding whether children with inner ear
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anomalies are at increased risk of experiencing surgical complications. In our cohort, patients with low risk anatomy were significantly older at the time of
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surgery compared to patients with normal or high risk anatomy. The most common low risk
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abnormality was EVA, an anomaly which can be associated with progressive hearing loss [12]. Therefore, these children often become audiologic candidates for cochlear implantation later in
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life. It is possible that this difference in age and indeed the process of determining when to
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implant a child with progressive hearing loss could influence the post cochlear implant hearing outcomes for this group. Close monitoring of hearing in patients with EVA is important to ensure that these children can be identified as candidates for implantation as early as possible to optimize hearing outcomes. Despite some variation in the literature, our study is similar to other previously published studies. Our findings are consistent with a study by Isaiah et al, which showed significant differences in hearing outcomes following surgery for children with cochlear anomalies [7]. One exception noted by Isaiah et al. is that children with EVA had results comparable to children
Journal Pre-proof with normal anatomy, which differs from our findings in the low risk anatomy group. However, this may be because their primary outcome was speech testing, whereas our study focused on PTA due to the limited number of preoperative WRS data available. Chadha et al. reported that children with cochlear abnormalities were not at increased risk for surgical complications or poorer hearing outcomes following cochlear implant surgery, though children with EVA were not included in this cohort [10]. In a study by Bille et al., cochlear abnormalities did not
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significantly impact long term category of auditory performance (CAP) and speech intelligibility
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rating (SIR) scores [9]; however, since those subjects underwent implantation between 2003-
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2007, it is possible that the clinical management of these cases have changed over time which
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could influence hearing outcomes in this population.
This study highlights the challenges of obtaining consistent audiologic data in young
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children to evaluate changes in hearing following cochlear implant surgery. Because many
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children at our institution were implanted at a very young age, speech testing is not possible before and immediately after surgery since these patients may not have developed speech prior to
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surgery. Similarly, in these young patients, threshold testing is sometimes incomplete and may
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only contain a single data point. This challenge hinders our analysis for this young group. Future prospective studies may help to standardize the collection of audiologic data. A universal standard test battery for pediatric cochlear implant patients would be a welcome addition to the field. There are limitations to our study. Audiologic data was not available for some patients at specific timepoints. This was most notable for word recognition scores, which were often not measured around the time of surgery because most patients were implanted at a very young age. For some hearing tests, only sound field test results were available, therefore making it
Journal Pre-proof challenging to evaluate changes in hearing specific to the surgical ear. We are unable to conclude whether specific abnormalities within each subgroup are associated with poorer hearing outcomes compared to others. A few subjects had comorbidities, such as developmental delay and autism, which could interfere with the results obtained during their audiologic testing. Because our institution serves many international families, postoperative follow up was often limited for these patients. Additionally, it is possible that other factors, such as socioeconomic
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status or school setting, could influence a patient’s hearing development.
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5. Conclusion
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In conclusion, this study suggests that the presence of inner ear abnormalities impacts hearing outcomes following cochlear implant surgery. The severity of such anomalies did not
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significantly affect postoperative hearing outcomes in this population. Given the inconsistent
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findings in the literature, future studies should consider a prospective, multisite approach with
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standardized testing and a larger sample size.
Journal Pre-proof 6. Acknowledgements
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Ms. Ronner was involved in execution of the study, acquisition of data, analysis and interpretation of data, drafting the article, and final approval of the manuscript as submitted. Dr. Basonbul assisted in acquisition of data, analysis and interpretation of data, and final approval of the manuscript as submitted. Dr. Bhakta assisted in execution of the study and final approval of the manuscript as submitted. I would also like to thank Dr. Kevin Franck for critical review of this manuscript. Drs. Mankarious, Lee, and Cohen were involved in planning and execution of the study, as well as critical review and revision of the manuscript and approval of the final manuscript as submitted.
Journal Pre-proof 7. References 1. Hawley KA, Goldberg DM, Anne S. Utility of a multidisciplinary approach to pediatric hearing loss. Am J Otolaryngol. 2017;38(5):547-550. doi:10.1016/j.amjoto.2017.05.008 2. Shulman S, Besculides M, Saltzman A, Ireys H, White K, Forsman I. Evaluation of the universal newborn hearing screening and intervention program. Pediatrics. 2010;Aug;126 Suppl 1:S19-27. doi: 10.1542/peds.2010-0354F. 3. Wentland CJ, Ronner EA, Basonbul RA, Pinnapureddy S, Mankarious L, Keamy D, Lee DJ, Cohen MS. Utilization of diagnostic testing for pediatric sensorineural hearing loss.
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Int J Pediatr Otorhinolaryngol. 2018 Aug;111:26-31. doi: 10.1016/j.ijporl.2018.05.024. 4. Mudry A, Mills, M. The Early History of the Cochlear Implant: A Retrospective. JAMA
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Otolaryngol Head Neck Surg. 2013 May;139(5):446-53. doi: 10.1001/jamaoto.2013.293. 5. Daya H, Figueirido JC, Gordon KA, Twitchell K, Gysin C, Papsin BC. The role of a
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graded profile analysis in determining candidacy and outcome for cochlear implantation in children. Int J Pediatr Otorhinolaryngol. 1999;49(2), 135-142.
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6. Young, JY, Ryan ME, Young NM. (2014). Preoperative imaging of sensorineural hearing loss in pediatric candidates for cochlear implantation. Radiographics. 2014 Sep-
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Oct;34(5):E133-49. doi: 10.1148/rg.345130083. 7. Isaiah A, Lee A, Lenes-Voit F, Sweeney M, Kutz W, Isaacson B, Roland P, Lee, KH.
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Clinical outcomes following cochlear implantation in children with inner ear anomalies. Int J Pediatr Otorhinolaryngol. 2017 Feb;93:1-6. doi: 10.1016/j.ijporl.2016.12.001.
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8. Papsin, B. Cochlear Implantation in Children With Anomalous Cochleovestibular Anatomy. Laryngoscope. 2005 Jan;115(S106):1-26
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9. Bille J., Fink-Jensen V, Ovesen T. (2015). Outcome of cochlear implantation in children with cochlear malformations. Eur Arch Otorhinolaryngol. 2015 Mar;272(3):583-9. doi: 10.1007/s00405-014-2883-z. 10. Chadha N, James A, Gordon K, Blaser S, Papsin, B. (2009). Bilateral Cochlear Implantation in Children With Anomalous Cochleovestibular Anatomy. Arch Otolaryngol Head Neck Surg. 2009 Sep;135(9):903-9. doi: 10.1001/archoto.2009.120. 11. Pakdaman MN1, Herrmann BS, Curtin HD, Van Beek-King J, Lee DJ. Cochlear implantation in children with anomalous cochleovestibular anatomy: a systematic review. Otolaryngol Head Neck Surg. 2012 Feb;146(2):180-90. doi: 10.1177/0194599811429244. 12. Madden C, Halsted M, Benton C, Greinwald J, Choo D. (2003). Enlarged vestibular aqueduct syndrome in the pediatric population. Otol Neurotol. 2003 Jul;24(4):625-32.
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Table 1. Patient Demographics distributed by number of ears
Total Patients
Normal anatomy N (%)
Low risk anatomy N (%)
High risk anatomy N (%)
p-value**
107 (100)
31 (100)
16 (100)
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55 (51) 52 (49)
18 (58) 13 (42)
7 (44) 9 (56)
Ear implanted Left Right
4.4 (1-12)
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Preoperative comorbidities Congenital CMV Developmental delay Connexin 26 mutation Pendred syndrome Mitochondrial disease Meningitis CHARGE syndrome Autism Seizure disorder Cleft lip and palate Malaria Cerebral palsy Paroxysmal tonic upgaze Other genetic abnormality None
12 (39) 19 (61)
0.01 2.8 (0-15) 0.52 9 (56) 7 (44) 0.21
44 (41) 30 (28) 33 (31)
19 (61) 3 (10) 9 (29)
7 (44) 1 (6) 8 (50)
10 (9) 5 (5) 3 (3) 0 (0) 1 (1) 0 (0) 0 (0) 3 (3) 2 (2) 1 (1) 2 (2) 1 (1) 0 (0) 4 (4) 72 (67)
1 (3) 1 (3) 0 (0) 3 (10) 0 (0) 0 (0) 0 (0) 1 (3) 0 (0) 0 (0) 0 (0) 0 (0) 1 (3) 2 (6) 16 (52)
0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 2 (12) 2 (12) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 1 (6) 11 (69)
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Preoperative imaging CT only MRI only CT and MRI
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49 (46) 58 (54)
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2.8 (0-15)
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Mean age at surgery in years (range)
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0.64
Gender Male Female
0.01
Journal Pre-proof CI* manufacturer Advanced Bionics Cochlear MED-EL Not specified
0.01 52 (49) 31 (29) 11 (10) 13 (12)
14 (45) 4 (13) 1 (3) 12 (39)
9 (56) 7 (44) 0 (0) 0 (0) 0.64
Postop complications Device failure Electrode misplacement Vertigo Mean length of audiology follow up in months (range)
0 (0) 0 (0) 2 (6)
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3 (3) 2 (2) 0 (0)
40 (0-113)
20 (0-56)
0 (0) 0 (0) 0 (0)
55 (5-113)
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*Note: CI = cochlear implant ** Chi square or Fisher’s exact test *** Kruskal-wallis test
0.01 ***
Journal Pre-proof Table 2. Summary of Anomalies per ear N=154 ears
No anomalies
107
Low risk anomalies Enlarged vestibular aqueduct Lateral semicircular canal abnormalities IP-II Wide internal auditory canal
22 15 12 1
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Anomalies
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High risk anomalies Cochlear nerve deficiency Cochlear hypoplasia Cochlear dysplasia Cochlear aperture abnormalities Common cavity deformity
8 6 3 2 2
Journal Pre-proof Table 3. Number of patients with available hearing test results over time Preop N (%)
3 months postop N (%)
12 months postop N (%)
95 (89)
83 (78)
75 (70)
Low risk anatomy (N = 31)
25 (81)
23 (74)
18 (58)
High risk anatomy ( N = 16)
15 (93)
11 (69)
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Normal anatomy (N = 107 ears)
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Pure tone audiometry
13 (81)
13 (12)
Low risk anatomy (N = 31) High risk anatomy ( N = 16)
21 (20)
6 (19)
11 (35)
14 (45)
3 (19)
5 (31)
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13 (12)
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Normal anatomy (N = 107 ears)
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Word recognition scores
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2 (13)
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Figure 1. Mean pure tone average (PTA) following cochlear implant surgery. Note: PTA = pure tone average. All PTA values are reported in decibels. *p<0.05
Journal Pre-proof NORMAL ANATOMY Pre-treatment (n=12 ears)
Post-treatment (n=53 ears)
WRS in affected ear (%)
WRS in affected ear (%)
PTA 100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
PTA 100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
0-10
0-10
11-20
11-20
21-30
21-30
1 12
12
7
31-40
31-40
1
4
8
41-50
1
41-50
1
51-60
1
1
1
1
71-80
1
81-90
2 1
81-90
1
>91
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>91
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61-70
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71-80
1
51-60
1
61-70
2
LOW RISK ANATOMY
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Pre-treatment (n=5 ears)
Post-treatment (n=20 ears)
WRS in affected ear (%) PTA
100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
31-40 41-50
11-20
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11-20
PTA 100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0 0-10
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0-10
21-30
WRS in affected ear (%)
21-30
1
31-40
1
51-60
61-70
61-70
71-80
71-80
>91
1 1
2 4
2
81-90 >91
2 1
41-50
51-60
81-90
4
1
1
1
Journal Pre-proof HIGH RISK ANATOMY Pre-treatment (n=2 ear)
Post-treatment (n=11 ears)
WRS in affected ear (%) PTA
WRS in affected ear (%) PTA 100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
100-90 89-80 79-70 69-60 59-50 49-40 39-30 29-20 19-10 9-0
0-10
0-10
11-20
11-20
21-30
21-30
3
31-40
31-40
2
41-50
41-50
51-60
51-60
61-70
61-70
71-80
71-80
81-90
81-90
1
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1
1
2
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1
>91
1
>91
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Figure 2. Preoperative and postoperative hearing testing for pediatric patients who underwent cochlear implant surgery with either normal, low risk, or high risk inner ear anatomy. Note: PTA = pure tone average. WRS = word recognition score. Post-treatment values represent the most recent testing obtained as of April 2019.
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