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Effectiveness of cochlear implant in inner ear bone malformations with anterior labyrinth involvement
International Journal of Pediatric Otorhinolaryngology 79 (2015) 369–373
Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl
Effectiveness of cochlear implant in inner ear bone malformations with anterior labyrinth involvement Juan Miguel Palomeque Vera a,b,*, Javier Go´mez-Herva´s a,c, Marı´a Ferna´ndez-Prada d,e, Alba-Saida Garcı´a Negro a, Amanda Rocı´o Gonza´lez Ramı´rez f, Manuel Sainz Quevedo a a
Cochlear Implant Unit, Department of Otolaryngology, San Cecilio University Hospital, Granada, Spain Department of Otolaryngology, Costa del Sol Hospital, Marbella, Ma´laga, Spain Department of Otolaryngology, La Inmaculada Hospital, Hue´rcal-Overa, Almerı´a, Spain d Clinical Unit of Preventive Medicine, Vigilance and Health Promotion, San Cecilio University Hospital, Granada, Spain e Department of Preventive Medicine and Public Health, University Hospital Central de Asturias, Oviedo, Spain f Fundacio´n Pu´blica Andaluza para la Investigacio´n Biosanitaria de Andalucı´a Oriental - Alejandro Otero, San Cecilio University Hospital, Granada, Spain b c
A R T I C L E I N F O
A B S T R A C T
Article history: Received 26 June 2014 Received in revised form 17 December 2014 Accepted 22 December 2014 Available online 31 December 2014
Objective: To study electrical stimulation, auditory functionality, and language development in patients with inner ear malformations involving the anterior labyrinth who underwent cochlear implantation. Study design: Retrospective case review. Setting: Reference hospital for cochlear implantation. Patients: Review of 14 cases of severe hearing loss with major (common cavity deformity and cochlear hypoplasia) or minor (e.g., incomplete partition and basal turn aplasia) malformations. Interventions: After cochlear implantation, data were gathered on the threshold (THR) and maximum comfort level (MCL) of the electrical stimulation and the number of functioning electrodes. Auditory responses to speech (EARS protocol) subtests were used to evaluate auditory functionality and language acquisition at 6, 12, and 24 months post-implantation. Tests used were: LIP profile, MTP (3, 6 and 12 words), OLD (open set test) and CLD (close set test). Results were compared with findings in a control group of 28 cochlear implantation patients without these malformations and with congenital hearing loss. Results: The mean THR was 11.02 mC in patients with malformations versus 3.5 mC in those without, a significant difference. The THR also significantly differed between groups with major and minor malformations. Fewer functioning electrodes were used in patients with malformations. Auditory functionality scores were best in controls than in patients with malformations, who scored 50%, finding the lowest scores in those with major malformations. Conclusion: Patients with inner ear malformations undergoing cochlear implantation require greater stimuli to obtain an auditory response and have worse auditory functionality outcomes; these differences are greater in those with major versus minor malformations Nevertheless, cochlear implantation appears to be beneficial for all patients with these malformations to a greater or lesser extent. ß 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Hearing loss Cochlear implantation Anterior labyrinth bone malformations
1. Introduction Inner ear bone malformation, one cause of profound hearing loss [1,2], The hearing impairment is directly related to the degree
of malformation and has a negative impact on the language development and social [3], personal and professional life of these patients [4]. It is possible to reduce these limitations by early diagnosis, prosthetic treatment with hearing aids, or cochlear
Abbreviations: CHARGE, Coloboma, heart defects, choanal atresia, growth retardation, genital hypoplasia, ear anomalies and deafness; LIP-Profile, listening progress profile; MTP, Monosyllabic-Trochee-Polysyllabic-Word Test; OLD, open list disyllabics (open set test); CLD, closed list disyllabics (closed set test); MRI, magnetic resonance imaging; CT, computed tomography; THR, threshold of electrical stimulation; MCL, maximum comfort level; IAC, inner auditory canal; mC, microcoulomb. * Corresponding author at: Costal del Sol Hospital, Autovı´a A-7, Km 187, 29603, Marbella, Ma´laga, Spain. Tel.: +34 650191924. E-mail address: [email protected] (J.M. Palomeque Vera). http://dx.doi.org/10.1016/j.ijporl.2014.12.029 0165-5876/ß 2014 Elsevier Ireland Ltd. All rights reserved.
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J.M. Palomeque Vera et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 369–373
implantation and rehabilitation. The cochlear implantation can benefit patients with inner ear malformations, just not as much as those without malformations [5]. These malformations can appear in isolation or in association with a syndrome, e.g., the CHARGE (Coloboma, Heart defects, Choanal Atresia, Growth Retardation, Genital hypoplasia, Ear anomalies and deafness), Waarderburg, Branchio-oto-renal, Usher, or Pendred syndrome, among others [6]. The malformations are radiologically classified as anterior (cochlear involvement) or posterior (vestibule or semicircular canals) [7]. Congenital inner ear malformations alter the distribution, specialization, and number of functioning nerve fibers in the cochlea, causing a hearing deficit. The diagnosis and classification of patients with these malformations has been improved by the utilization of CT to study the bony labyrinth and of magnetic resonance imaging (MRI) to examine the membranous labyrinth and cochlear nerve [7]. Sennaroglu et al. [8] divided cochlear malformations into: common cavity deformity, cochlear aplasia, cochlear hypoplasia, and types I and II incomplete partition (type II is also known as Mondini malformation). Casselman et al. [9] classified malformations that involve the inner ear canal, which must be ruled out in all candidates for cochlear implantation, because inner ear canal stenosis may involve cochlear nerve agenesis, a contraindication for this procedure [10]. The aim of cochlear implantation is stimulate the auditory structures of the inner ear, through a coded signal is sent to the electrode array, which directly stimulates the auditory nerve. It allows study of the functionality of the different intra-cochlear areas, based on the localization of each intra-cochlear electrode and the electrical stimulation parameters. Moreover, this study and post-implant auditory–verbal rehabilitation assist in improving the auditory functionality and language development of patients [5,11]. The main objective of this investigation was to analyze electrical stimulation parameters during cochlear implant programming in patients with inner ear bone malformations involving the anterior labyrinth as a function of the type of malformation. A secondary objective was to assess their auditory functionality and language development. The rationale of the study objectives in these children who had inner ear malformations (major and minor) is of great interest because it allows to know the advantages in the cochlear implantation in these patients. This topic explain the understanding factors variability in their performance will aid with therapeutic intervention and setting realistic expectations for parents and clinicians. 2. Material and methods A case-control, observational, retrospective study was undertaken in consecutive patients with inner ear bone malformation involving the anterior labyrinth who received a cochlear implant between January 2006 and December 2011 in San Cecilio University Hospital, Granada, Spain. No exclusion criteria were applied, and the sample included all 14 patients; the distribution of the sample by sex and mean age at implantation is shown in Table 1. Before cochlear implantation, all patients underwent helical high-resolution computed tomography (CT) in slices of 0.5–1 mm for diagnostic and morphologic examination of the inner ear and magnetic resonance imaging (MRI) to examine the membranous labyrinth and cochlear nerve [7]. The following malformations were detected in six patients had major malformations: cochlear hypoplasia (n = 4, 28.57%) and common cavity deformity (n = 2, 14.28%). We considered the malformations for the remaining eight
Table 1 Distribution of patients in case and control groups.
Number of patients Sex Age at implantation (mean) Age (median)
Patient with malformationa (cases)
Patient without malformation (controls)
14 10 males (71.42%) 4 females (28.57%) 10.80 years (SD 14.95)
28 17 males (60.7%) 11 females (39.3%) 9.68 years (SD 13.72)
4 years
2.5 years
a
Malformation, inner ear bone malformation with anterior labyrinth involvement.
patients as minor: type I incomplete partition (n = 2, 14.28%), type II incomplete partition (Mondini malformation) (n = 2, 14.28%), basal turn aplasia (n = 2, 14.28%) and basal turn stenosis (n = 2, 14.28). Four patients (28.57%) had associated syndromes: CHARGE syndrome with cochlear hypoplasia (n = 2); Digeorge syndrome with Mondini malformation (n = 1), and karyotype 46 XX with Mondini malformation (n = 1). We also studied a pair-matched control group of 28 cochlear implant patients without inner ear anomalies and with congenital hearing loss. These patients were not cases of genetic syndromic. The following cochlear implants were used in both groups (malformations group versus control group): Medel Pulsar CI100 (Innsbruck, Austria) (n = 12 vs n = 9), Advance Bionics Hires 90k (Laubisru¨tistrasse, Switzerland) (n = 1 vs n = 11) and Cochlear Nucleus (Macquarie University, Australia) (n = 1 vs n = 8). In our patients different electrodes arrays configurations were not used (short, split, etc.). After cochlear implantation and its activation and programming, data were gathered on the THR and MCL (both in microcoulombs) and number of active electrodes. Auditory functionality scores (percentage 0–100% of correct answers) were obtained at 6, 12, and 24 months in the following subtests: LIP profile, MTP 3 words, MTP 6 words, MTP 12 words, OLD (open set test) and CLD (closed set test) from the EARS (evaluation of auditory responses to speech) test battery [12,13], developed by the Department of Clinical Research of MEDEL (Innsbruck, Austria). In the Statistical analysis was used as the sample size (n < 30) non parametric test. The Chi-square test was used to compare proportions between groups (cases and controls) and when it did not meet the conditions of validity, Fisher’s exact test was applied. In the analysis of differences were held Mann–Whitney U (to analyze the differences between the mean values of quantitative variables between two groups of study) and Kruskal–Wallis test (was used to compare mean differences in more than two groups). Table 2 displays the values of Mann–Whitney U, Z and P in the different variables of study. 3. Results Fig. 1 shows the stimulation THR values obtained in the programming procedure. Mean THR values and number of functioning electrodes significantly differed (p < 0.05) between the patients with anterior labyrinth malformations and the controls and between the patients with major malformations and minor malformations. MCL not show significantly differed between both groups. Table 3 displays the auditory perception test results. Significant differences (p < 0.05) were found between the patients with malformations and the controls in: LIP at 12 and 24 months postimplantation; MTP 3 words and MTP 6 words at 6, 12, and 24 months; MTP 12 words at 12 and 24 months; CLD at 6, 12, and 24 months; and OLD at 12 and 24 months. Significant differences
J.M. Palomeque Vera et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 369–373 Table 2 Values of Mann–Whitney U, Z and P in the different variables of study. Variables
Mann–Whitney U
Z
P (bilateral significant)
THR N8 functioning electrodes LIP at 6 LIP at 12 LIP at 24 MTP 3 at 6 MTP 3 at 12 MTP 3 at 24 MTP 6 at 6 MTP 6 at 12 MTP 6 at 24 MTP 12 at 6 MTP 12 at 12 MTP 12 at 24 CLD at 6 CLD at 12 CLD at 24 OLD at 6 OLD at 12 OLD at 24
32.5 24.5
2.6 2.9
0.009 0.002
77 74.5 45 81.5 70.5 51 78 74 65 81.5 65 59.5 81 59 46 76 70 55.5
0.421 0.546 2.076 0.204 0.760 1.792 0.401 0.573 1.018 0.274 1.119 1.3 0.688 1.572 2.042 1.453 1.003 1.605
0.674 0.585 0.038 0.838 0.468 0.095 0.735 0.595 0.332 0.847 0.332 0.205 0.491 0.116 0.041 0.146 0.316 0.108
371
(p < 0.05) were also observed between the major and minor malformation groups in: LIP at 12 and 24 months post-implantation, MTP 12 words at 24 months, and CLD at 24 months. 4. Discussion Profound hearing loss is the most frequent sensorineural disorder in newborns, with incidences of 0.8–3 cases per 1.000 deliveries in the USA and 1.5–2 per 1000 in Europe [10]. Cochlear malformations have been reported to occur in approximately 20% of children with congenital sensorineural hearing loss; bony malformations can appear in 20%, being more frequent incomplete partition and cochlear hypoplasia [1,7,8] (Fig. 2). Cochlear implantation has proven an effective treatment for this condition, but doubts remain about its usefulness and viability in patients with congenital inner ear malformations [14]. At cochlear implantation, auditory functionality can be assessed by studying intracochlear electrical stimulation data. In the present study, mean THR values were significantly higher in the patients with inner ear malformations than in those without, as previously reported by MacArdle et al. [15] and Sainz et al. [16,17]. The number of functioning electrodes was also significantly lower in the patients with malformations and in those with major versus minor malformations; this is because electrodes that cannot effectively stimulate areas with malformations are switched off
Fig. 1. Number of functioning electrodes and THR value in cases with major and minor malformations and in controls. Major malformation, common cavity deformity or cochlear hypoplasia; minor malformations, all other malformations; mC, microcoulomb.
J.M. Palomeque Vera et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 369–373
372
Table 3 Distribution of scores in auditory functionality tests among study groups. Auditory perception tests at 6, 12, and 24 monthsa
Any malformation (mean/SD)
No malformation (mean/SD)
Significant differencesb (p < 0.05)
Major malformation (mean/SD)
Minor malformation (mean/SD)
Significant differencesc (p < 0.05)
LIP at 6 LIP at 12 LIP at 24 MTP 3 at 6 MTP 3 at 12 MTP 3 at 24 MTP 6 at 6 MTP 6 at 12 MTP 6 at 24 MTP 12 at 6 MTP 12 at 12 MTP 12 at 24 CLD at 6 CLD at 12 CLD at 24 OLD at 6 OLD at 12 OLD at 24
49.14% 55.43% 66.93% 25.95% 43.79% 63.36% 11.29% 29.71% 50.43% 17% 18% 44.79% 0% 17.43% 39.43% 0% 8.5% 22.79%
65.57% 83.14% 96.54% 40.46% 81.61% 98.96% 25.14% 71.64% 95.29% 13.64% 40.39% 86.18% 0% 17.14% 75.36% 0% 6.07% 63.57%
– p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 – p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 – p < 0.05 p < 0.05
47.11% 54.89% 62.67% 28.67% 44.67% 55.44% 17.22% 32.22% 42% 20% 15.56% 30.56% 0% 7.78% 14.44% 3.53% 6.67% 12.22%
51.79% 60.63% 81.26% 39.58% 58.79% 75.68% 22.68% 40.53% 58.58% 12.74% 31.89% 50.89% 3.68% 27.79% 52.37% 0% 15.47% 30.47%
– p < 0.05 p < 0.05 – – – – – – – – p < 0.05 – – p < 0.05 – – –
a b c
(28.64) (28.88) (32.16) (33.23) (38.35) (36.10) (37.91) (33.74) (24.97) (34.51) (29.84) (37.28) (0) (29.80) (40.86) (0) (21.67) (28.87)
(29.93) (20.96) (9.2) (44.78) (27.78) (4.08) (35.43) (22.43) (9.98) (27.04) (35.67) (18.72) (0) (30.83) (25.48) (0) (19.87) (30.76)
(24.74) (24.98) (23.67) (29.93) (33.94) (31.65) (32.41) (36.23) (31.5) (40) (28.19) (33.20) (23.33) (32.73) (10) (20) (29.90)
(37.99) (36.89) (30.87) (44.25) (43.66) (37.02) (32.47) (35.87) (38.91) (28.47) (39.78) (40.03) (16.05) (34.15) (42.87) (29.37) (31.5)
Subtests were used to evaluate auditory functionality and language acquisition at 6, 12, and 24 months post-implantation. Significant differences (p < 0.05), between patients with any malformations and patients without malformations. Significant differences (p < 0.05), between patients with major malformations and patients with minor malformations.
Fig. 2. Images. The first image (arrow) signs a common cavity deformity and the second image (asterisks) a types II incomplete partition (Mondini malformation).
[18]. No significant difference in MCL was observed between patients with and without malformations or between patients with major and minor malformations, as also found by Sainz et al. [16,17]. All patients, including the controls, evidenced an improvement in auditory function after cochlear implantation and rehabilitation. However, the results of all auditory function tests were significantly worse at both 12 and 24 months post-implantation in those with malformations than in those without, in agreement with reports by Wan [19] and Rachovitsas [20]. This finding can be explained by the deficient cochlear development, lack of tonotopy, and atypical distribution of cochlear nerve structures in those with malformations [17], who also had fewer active electrodes. Test results were also significantly worse, although to a smaller degree, in those with major versus minor malformations at 24 months, which would again be influenced by the lower number of active electrodes used in the former group [21]. In our series of 14 patients with inner ear bone malformations involving the anterior labyrinth, 2 had the CHARGE syndrome, which is frequently associated with cochlear hypoplasia [22], as in the present cases. Semicircular canal absence, Mondini malformation, or, more rarely, enlarged vestibular aqueduct can also be found in patients with this syndrome [23]. Its association with psychomotor deficit means that worse functional outcomes are obtained after implantation. Although the implant enhanced the children’s ‘connectivity’ to the environment, it did not promote the development of oral language skills in this population [22]. DiGeorge
syndrome is frequently associated with Mondini malformation [24], as observed in one of the present patients. Some authors attributed poor auditory outcomes of cochlear implantation in patients with common cavity deformity to a deficient stimulation, related to the altered distribution of ganglion structures within the cochlea [21,25]. Others suggested that this treatment is not predictable in patients with major malformations [26–28]. In the present study, auditory function results were significantly worse in the patients with common cavity deformity or cochlear hypoplasia (major malformations) than in those with other (minor) malformations [29,30]. Those with a major malformation were unable to correctly identify >50% of the words in the tests and would therefore have difficulties in holding a conversation with no visual cues [31–33]. The frequency of inner ear bone malformations is very low, explaining the reduced sample size in the present study, although it is relatively large in comparison to previous reports. Further research in larger samples is required to establish definitive conclusions. 5. Conclusion Patients with major inner ear malformations undergoing cochlear implantation require a greater stimulus to obtain an auditory response and evidence a slower and worse acquisition of auditory functionality in comparison to those with minor or no inner ear malformations. Nevertheless, cochlear implantation
J.M. Palomeque Vera et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 369–373
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Contents lists available at ScienceDirect
International Journal of Pediatric Otorhinolaryngology journal homepage: www.elsevier.com/locate/ijporl
Effectiveness of cochlear implant in inner ear bone malformations with anterior labyrinth involvement Juan Miguel Palomeque Vera a,b,*, Javier Go´mez-Herva´s a,c, Marı´a Ferna´ndez-Prada d,e, Alba-Saida Garcı´a Negro a, Amanda Rocı´o Gonza´lez Ramı´rez f, Manuel Sainz Quevedo a a
Cochlear Implant Unit, Department of Otolaryngology, San Cecilio University Hospital, Granada, Spain Department of Otolaryngology, Costa del Sol Hospital, Marbella, Ma´laga, Spain Department of Otolaryngology, La Inmaculada Hospital, Hue´rcal-Overa, Almerı´a, Spain d Clinical Unit of Preventive Medicine, Vigilance and Health Promotion, San Cecilio University Hospital, Granada, Spain e Department of Preventive Medicine and Public Health, University Hospital Central de Asturias, Oviedo, Spain f Fundacio´n Pu´blica Andaluza para la Investigacio´n Biosanitaria de Andalucı´a Oriental - Alejandro Otero, San Cecilio University Hospital, Granada, Spain b c
A R T I C L E I N F O
A B S T R A C T
Article history: Received 26 June 2014 Received in revised form 17 December 2014 Accepted 22 December 2014 Available online 31 December 2014
Objective: To study electrical stimulation, auditory functionality, and language development in patients with inner ear malformations involving the anterior labyrinth who underwent cochlear implantation. Study design: Retrospective case review. Setting: Reference hospital for cochlear implantation. Patients: Review of 14 cases of severe hearing loss with major (common cavity deformity and cochlear hypoplasia) or minor (e.g., incomplete partition and basal turn aplasia) malformations. Interventions: After cochlear implantation, data were gathered on the threshold (THR) and maximum comfort level (MCL) of the electrical stimulation and the number of functioning electrodes. Auditory responses to speech (EARS protocol) subtests were used to evaluate auditory functionality and language acquisition at 6, 12, and 24 months post-implantation. Tests used were: LIP profile, MTP (3, 6 and 12 words), OLD (open set test) and CLD (close set test). Results were compared with findings in a control group of 28 cochlear implantation patients without these malformations and with congenital hearing loss. Results: The mean THR was 11.02 mC in patients with malformations versus 3.5 mC in those without, a significant difference. The THR also significantly differed between groups with major and minor malformations. Fewer functioning electrodes were used in patients with malformations. Auditory functionality scores were best in controls than in patients with malformations, who scored 50%, finding the lowest scores in those with major malformations. Conclusion: Patients with inner ear malformations undergoing cochlear implantation require greater stimuli to obtain an auditory response and have worse auditory functionality outcomes; these differences are greater in those with major versus minor malformations Nevertheless, cochlear implantation appears to be beneficial for all patients with these malformations to a greater or lesser extent. ß 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Hearing loss Cochlear implantation Anterior labyrinth bone malformations
1. Introduction Inner ear bone malformation, one cause of profound hearing loss [1,2], The hearing impairment is directly related to the degree
of malformation and has a negative impact on the language development and social [3], personal and professional life of these patients [4]. It is possible to reduce these limitations by early diagnosis, prosthetic treatment with hearing aids, or cochlear
Abbreviations: CHARGE, Coloboma, heart defects, choanal atresia, growth retardation, genital hypoplasia, ear anomalies and deafness; LIP-Profile, listening progress profile; MTP, Monosyllabic-Trochee-Polysyllabic-Word Test; OLD, open list disyllabics (open set test); CLD, closed list disyllabics (closed set test); MRI, magnetic resonance imaging; CT, computed tomography; THR, threshold of electrical stimulation; MCL, maximum comfort level; IAC, inner auditory canal; mC, microcoulomb. * Corresponding author at: Costal del Sol Hospital, Autovı´a A-7, Km 187, 29603, Marbella, Ma´laga, Spain. Tel.: +34 650191924. E-mail address: [email protected] (J.M. Palomeque Vera). http://dx.doi.org/10.1016/j.ijporl.2014.12.029 0165-5876/ß 2014 Elsevier Ireland Ltd. All rights reserved.
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implantation and rehabilitation. The cochlear implantation can benefit patients with inner ear malformations, just not as much as those without malformations [5]. These malformations can appear in isolation or in association with a syndrome, e.g., the CHARGE (Coloboma, Heart defects, Choanal Atresia, Growth Retardation, Genital hypoplasia, Ear anomalies and deafness), Waarderburg, Branchio-oto-renal, Usher, or Pendred syndrome, among others [6]. The malformations are radiologically classified as anterior (cochlear involvement) or posterior (vestibule or semicircular canals) [7]. Congenital inner ear malformations alter the distribution, specialization, and number of functioning nerve fibers in the cochlea, causing a hearing deficit. The diagnosis and classification of patients with these malformations has been improved by the utilization of CT to study the bony labyrinth and of magnetic resonance imaging (MRI) to examine the membranous labyrinth and cochlear nerve [7]. Sennaroglu et al. [8] divided cochlear malformations into: common cavity deformity, cochlear aplasia, cochlear hypoplasia, and types I and II incomplete partition (type II is also known as Mondini malformation). Casselman et al. [9] classified malformations that involve the inner ear canal, which must be ruled out in all candidates for cochlear implantation, because inner ear canal stenosis may involve cochlear nerve agenesis, a contraindication for this procedure [10]. The aim of cochlear implantation is stimulate the auditory structures of the inner ear, through a coded signal is sent to the electrode array, which directly stimulates the auditory nerve. It allows study of the functionality of the different intra-cochlear areas, based on the localization of each intra-cochlear electrode and the electrical stimulation parameters. Moreover, this study and post-implant auditory–verbal rehabilitation assist in improving the auditory functionality and language development of patients [5,11]. The main objective of this investigation was to analyze electrical stimulation parameters during cochlear implant programming in patients with inner ear bone malformations involving the anterior labyrinth as a function of the type of malformation. A secondary objective was to assess their auditory functionality and language development. The rationale of the study objectives in these children who had inner ear malformations (major and minor) is of great interest because it allows to know the advantages in the cochlear implantation in these patients. This topic explain the understanding factors variability in their performance will aid with therapeutic intervention and setting realistic expectations for parents and clinicians. 2. Material and methods A case-control, observational, retrospective study was undertaken in consecutive patients with inner ear bone malformation involving the anterior labyrinth who received a cochlear implant between January 2006 and December 2011 in San Cecilio University Hospital, Granada, Spain. No exclusion criteria were applied, and the sample included all 14 patients; the distribution of the sample by sex and mean age at implantation is shown in Table 1. Before cochlear implantation, all patients underwent helical high-resolution computed tomography (CT) in slices of 0.5–1 mm for diagnostic and morphologic examination of the inner ear and magnetic resonance imaging (MRI) to examine the membranous labyrinth and cochlear nerve [7]. The following malformations were detected in six patients had major malformations: cochlear hypoplasia (n = 4, 28.57%) and common cavity deformity (n = 2, 14.28%). We considered the malformations for the remaining eight
Table 1 Distribution of patients in case and control groups.
Number of patients Sex Age at implantation (mean) Age (median)
Patient with malformationa (cases)
Patient without malformation (controls)
14 10 males (71.42%) 4 females (28.57%) 10.80 years (SD 14.95)
28 17 males (60.7%) 11 females (39.3%) 9.68 years (SD 13.72)
4 years
2.5 years
a
Malformation, inner ear bone malformation with anterior labyrinth involvement.
patients as minor: type I incomplete partition (n = 2, 14.28%), type II incomplete partition (Mondini malformation) (n = 2, 14.28%), basal turn aplasia (n = 2, 14.28%) and basal turn stenosis (n = 2, 14.28). Four patients (28.57%) had associated syndromes: CHARGE syndrome with cochlear hypoplasia (n = 2); Digeorge syndrome with Mondini malformation (n = 1), and karyotype 46 XX with Mondini malformation (n = 1). We also studied a pair-matched control group of 28 cochlear implant patients without inner ear anomalies and with congenital hearing loss. These patients were not cases of genetic syndromic. The following cochlear implants were used in both groups (malformations group versus control group): Medel Pulsar CI100 (Innsbruck, Austria) (n = 12 vs n = 9), Advance Bionics Hires 90k (Laubisru¨tistrasse, Switzerland) (n = 1 vs n = 11) and Cochlear Nucleus (Macquarie University, Australia) (n = 1 vs n = 8). In our patients different electrodes arrays configurations were not used (short, split, etc.). After cochlear implantation and its activation and programming, data were gathered on the THR and MCL (both in microcoulombs) and number of active electrodes. Auditory functionality scores (percentage 0–100% of correct answers) were obtained at 6, 12, and 24 months in the following subtests: LIP profile, MTP 3 words, MTP 6 words, MTP 12 words, OLD (open set test) and CLD (closed set test) from the EARS (evaluation of auditory responses to speech) test battery [12,13], developed by the Department of Clinical Research of MEDEL (Innsbruck, Austria). In the Statistical analysis was used as the sample size (n < 30) non parametric test. The Chi-square test was used to compare proportions between groups (cases and controls) and when it did not meet the conditions of validity, Fisher’s exact test was applied. In the analysis of differences were held Mann–Whitney U (to analyze the differences between the mean values of quantitative variables between two groups of study) and Kruskal–Wallis test (was used to compare mean differences in more than two groups). Table 2 displays the values of Mann–Whitney U, Z and P in the different variables of study. 3. Results Fig. 1 shows the stimulation THR values obtained in the programming procedure. Mean THR values and number of functioning electrodes significantly differed (p < 0.05) between the patients with anterior labyrinth malformations and the controls and between the patients with major malformations and minor malformations. MCL not show significantly differed between both groups. Table 3 displays the auditory perception test results. Significant differences (p < 0.05) were found between the patients with malformations and the controls in: LIP at 12 and 24 months postimplantation; MTP 3 words and MTP 6 words at 6, 12, and 24 months; MTP 12 words at 12 and 24 months; CLD at 6, 12, and 24 months; and OLD at 12 and 24 months. Significant differences
J.M. Palomeque Vera et al. / International Journal of Pediatric Otorhinolaryngology 79 (2015) 369–373 Table 2 Values of Mann–Whitney U, Z and P in the different variables of study. Variables
Mann–Whitney U
Z
P (bilateral significant)
THR N8 functioning electrodes LIP at 6 LIP at 12 LIP at 24 MTP 3 at 6 MTP 3 at 12 MTP 3 at 24 MTP 6 at 6 MTP 6 at 12 MTP 6 at 24 MTP 12 at 6 MTP 12 at 12 MTP 12 at 24 CLD at 6 CLD at 12 CLD at 24 OLD at 6 OLD at 12 OLD at 24
32.5 24.5
2.6 2.9
0.009 0.002
77 74.5 45 81.5 70.5 51 78 74 65 81.5 65 59.5 81 59 46 76 70 55.5
0.421 0.546 2.076 0.204 0.760 1.792 0.401 0.573 1.018 0.274 1.119 1.3 0.688 1.572 2.042 1.453 1.003 1.605
0.674 0.585 0.038 0.838 0.468 0.095 0.735 0.595 0.332 0.847 0.332 0.205 0.491 0.116 0.041 0.146 0.316 0.108
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(p < 0.05) were also observed between the major and minor malformation groups in: LIP at 12 and 24 months post-implantation, MTP 12 words at 24 months, and CLD at 24 months. 4. Discussion Profound hearing loss is the most frequent sensorineural disorder in newborns, with incidences of 0.8–3 cases per 1.000 deliveries in the USA and 1.5–2 per 1000 in Europe [10]. Cochlear malformations have been reported to occur in approximately 20% of children with congenital sensorineural hearing loss; bony malformations can appear in 20%, being more frequent incomplete partition and cochlear hypoplasia [1,7,8] (Fig. 2). Cochlear implantation has proven an effective treatment for this condition, but doubts remain about its usefulness and viability in patients with congenital inner ear malformations [14]. At cochlear implantation, auditory functionality can be assessed by studying intracochlear electrical stimulation data. In the present study, mean THR values were significantly higher in the patients with inner ear malformations than in those without, as previously reported by MacArdle et al. [15] and Sainz et al. [16,17]. The number of functioning electrodes was also significantly lower in the patients with malformations and in those with major versus minor malformations; this is because electrodes that cannot effectively stimulate areas with malformations are switched off
Fig. 1. Number of functioning electrodes and THR value in cases with major and minor malformations and in controls. Major malformation, common cavity deformity or cochlear hypoplasia; minor malformations, all other malformations; mC, microcoulomb.
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Table 3 Distribution of scores in auditory functionality tests among study groups. Auditory perception tests at 6, 12, and 24 monthsa
Any malformation (mean/SD)
No malformation (mean/SD)
Significant differencesb (p < 0.05)
Major malformation (mean/SD)
Minor malformation (mean/SD)
Significant differencesc (p < 0.05)
LIP at 6 LIP at 12 LIP at 24 MTP 3 at 6 MTP 3 at 12 MTP 3 at 24 MTP 6 at 6 MTP 6 at 12 MTP 6 at 24 MTP 12 at 6 MTP 12 at 12 MTP 12 at 24 CLD at 6 CLD at 12 CLD at 24 OLD at 6 OLD at 12 OLD at 24
49.14% 55.43% 66.93% 25.95% 43.79% 63.36% 11.29% 29.71% 50.43% 17% 18% 44.79% 0% 17.43% 39.43% 0% 8.5% 22.79%
65.57% 83.14% 96.54% 40.46% 81.61% 98.96% 25.14% 71.64% 95.29% 13.64% 40.39% 86.18% 0% 17.14% 75.36% 0% 6.07% 63.57%
– p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 – p < 0.05 p < 0.05 p < 0.05 p < 0.05 p < 0.05 – p < 0.05 p < 0.05
47.11% 54.89% 62.67% 28.67% 44.67% 55.44% 17.22% 32.22% 42% 20% 15.56% 30.56% 0% 7.78% 14.44% 3.53% 6.67% 12.22%
51.79% 60.63% 81.26% 39.58% 58.79% 75.68% 22.68% 40.53% 58.58% 12.74% 31.89% 50.89% 3.68% 27.79% 52.37% 0% 15.47% 30.47%
– p < 0.05 p < 0.05 – – – – – – – – p < 0.05 – – p < 0.05 – – –
a b c
(28.64) (28.88) (32.16) (33.23) (38.35) (36.10) (37.91) (33.74) (24.97) (34.51) (29.84) (37.28) (0) (29.80) (40.86) (0) (21.67) (28.87)
(29.93) (20.96) (9.2) (44.78) (27.78) (4.08) (35.43) (22.43) (9.98) (27.04) (35.67) (18.72) (0) (30.83) (25.48) (0) (19.87) (30.76)
(24.74) (24.98) (23.67) (29.93) (33.94) (31.65) (32.41) (36.23) (31.5) (40) (28.19) (33.20) (23.33) (32.73) (10) (20) (29.90)
(37.99) (36.89) (30.87) (44.25) (43.66) (37.02) (32.47) (35.87) (38.91) (28.47) (39.78) (40.03) (16.05) (34.15) (42.87) (29.37) (31.5)
Subtests were used to evaluate auditory functionality and language acquisition at 6, 12, and 24 months post-implantation. Significant differences (p < 0.05), between patients with any malformations and patients without malformations. Significant differences (p < 0.05), between patients with major malformations and patients with minor malformations.
Fig. 2. Images. The first image (arrow) signs a common cavity deformity and the second image (asterisks) a types II incomplete partition (Mondini malformation).
[18]. No significant difference in MCL was observed between patients with and without malformations or between patients with major and minor malformations, as also found by Sainz et al. [16,17]. All patients, including the controls, evidenced an improvement in auditory function after cochlear implantation and rehabilitation. However, the results of all auditory function tests were significantly worse at both 12 and 24 months post-implantation in those with malformations than in those without, in agreement with reports by Wan [19] and Rachovitsas [20]. This finding can be explained by the deficient cochlear development, lack of tonotopy, and atypical distribution of cochlear nerve structures in those with malformations [17], who also had fewer active electrodes. Test results were also significantly worse, although to a smaller degree, in those with major versus minor malformations at 24 months, which would again be influenced by the lower number of active electrodes used in the former group [21]. In our series of 14 patients with inner ear bone malformations involving the anterior labyrinth, 2 had the CHARGE syndrome, which is frequently associated with cochlear hypoplasia [22], as in the present cases. Semicircular canal absence, Mondini malformation, or, more rarely, enlarged vestibular aqueduct can also be found in patients with this syndrome [23]. Its association with psychomotor deficit means that worse functional outcomes are obtained after implantation. Although the implant enhanced the children’s ‘connectivity’ to the environment, it did not promote the development of oral language skills in this population [22]. DiGeorge
syndrome is frequently associated with Mondini malformation [24], as observed in one of the present patients. Some authors attributed poor auditory outcomes of cochlear implantation in patients with common cavity deformity to a deficient stimulation, related to the altered distribution of ganglion structures within the cochlea [21,25]. Others suggested that this treatment is not predictable in patients with major malformations [26–28]. In the present study, auditory function results were significantly worse in the patients with common cavity deformity or cochlear hypoplasia (major malformations) than in those with other (minor) malformations [29,30]. Those with a major malformation were unable to correctly identify >50% of the words in the tests and would therefore have difficulties in holding a conversation with no visual cues [31–33]. The frequency of inner ear bone malformations is very low, explaining the reduced sample size in the present study, although it is relatively large in comparison to previous reports. Further research in larger samples is required to establish definitive conclusions. 5. Conclusion Patients with major inner ear malformations undergoing cochlear implantation require a greater stimulus to obtain an auditory response and evidence a slower and worse acquisition of auditory functionality in comparison to those with minor or no inner ear malformations. Nevertheless, cochlear implantation
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