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Audiologic and radiologic findings in cochlear hypoplasia
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ANL-2220; No. of Pages 9 Auris Nasus Larynx xxx (2016) xxx–xxx Contents lists available at ScienceDirect
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Audiologic and radiologic findings in cochlear hypoplasia Betul Cicek Cinar a,*, Merve Ozbal Batuk a, Emel Tahir b, Gonca Sennaroglu a, Levent Sennaroglu c a
Department of Audiology, Hacettepe University, Ankara, Turkey ˇˇ is¸kapˇˇ i Yˇˇidˇˇirˇˇim Beyazˇˇit Research and Training Hospital, Ankara, Turkey Ear-Nose-Throat Clinic, D c Department of Otolaryngology, Head and Neck Surgery, Hacettepe University, Ankara, Turkey b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 12 July 2016 Accepted 19 December 2016 Available online xxx
Objective: The aim of the current study is to evaluate audiologic and radiologic findings of cochlear hypoplasia which is a subgroup of inner ear malformations. Methods: This study was a prospective clinical study and based on voluntary participation from cases with cochlear hypoplasia diagnosis. The study was conducted at Hacettepe University, Department of Otolaryngology, Head and Neck Surgery and Department of Audiology. Subjects were selected from an inner ear malformations database. Inclusion criteria were having cochlear hypoplasia for at least one ear. There were 66 subjects with an age range of 12 months and 60 years 5 months. For each subject, pure tone audiometry and tympanometry were applied according to chronological and cognitive age. And also, auditory brainstem response test was applied to when it is need. Subjects’ radiologic results were reevaluated to confirm cochlear hypoplasia, cochlear nerve and cochlear aperture. Results: Cochlear hypoplasia types were statistically significantly different in terms of HL degree. This difference was caused by cochlear hypoplasia type IV group being was statistically different from the other three groups. Like with degree of HL, cochlear hypoplasia groups were statistically different from other three groups in terms of type of hearing loss. Cochlear aperture and cochlear nerve status showed variation according to cochlear hypoplasia type but these differences were not statistically approved. Conclusions: In the current study, incidence of cochlear hypoplasia was 23.5% in all inner ear malformation. With this study, it was seen that subtypes of cochlear hypoplasia showed variability in terms of degree and type of hearing loss and also cochlear aperture and cochlear nerve status. Especially cochlear hypoplasia type IV differs from other three cochlear hypoplasia types. ß 2016 Elsevier Ireland Ltd. All rights reserved.
Keywords: Audiological evaluation Inner ear malformation Cochlear hypoplasia Cochlear aperture Cochlear nerve Cochlear implantation
1. Introduction Inner ear malformations (IEMs) are the cause of congenital sensorineural hearing loss in approximately 20% of hearing impaired children [1]. IEM is used as a general term for all cochlea types that differ from normal
¨ niversitesi, Sag˘lık Bilimleri Faku¨ltesi, * Corresponding author at: Hacettepe U Odyoloji Bo¨lu¨mu¨ Sıhhiye, Ankara 06100, Turkey. E-mail address: [email protected] (B.C. Cinar).
structures. Sennaroglu et al. classified IEM by using computerized tomography (CT) and magnetic resonance imaging (MRI) [1,2]. This latest classification includes eight groups; labyrinthine aplasia (Michel deformity), rudimentary otocyst, cochlear aplasia, common cavity, incomplete partition (IP) of the cochlea (IP), cochlear hypoplasia (CH), large vestibular aqueduct syndrome (LVAS) and cochlear aperture abnormalities (CA) [2]. All these groups show variability in terms of radiological findings [1,3,4]. The latest classification is summarized in Table 1.
http://dx.doi.org/10.1016/j.anl.2016.12.002 0385-8146/ß 2016 Elsevier Ireland Ltd. All rights reserved.
Please cite this article in press as: Cinar BC, et al. Audiologic and radiologic findings in cochlear hypoplasia. Auris Nasus Larynx (2017), http:// dx.doi.org/10.1016/j.anl.2016.12.002
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ANL-2220; No. of Pages 9 B.C. Cinar et al. / Auris Nasus Larynx xxx (2016) xxx–xxx Cochlear aperture or cochlear nerve canal transmits the cochlear nerve from the Internal acoustic canal to the cochlea An enlarged vestibular aqueduct in the presence of a normal cochlea, vestibule and semicircular canals External dimensions are reduced relative to the normal cochlea. According to internal architecture, four different types of CH: CH-I, CH-II, CH-III and CH-IV External dimensions are similar to normal cochleae but the internal architecture is deficient. Three different types: (IP-I), incomplete (IP-II) and (IP-III) Short The cochlea, vestibule, explanations semicircular canals, vestibular and cochlear aqueducts are absent
Incomplete millimetric The cochlea representations of otic is absent capsule (round or ovoid in shape), without an internal auditory canal
Cochlea and vestibule are represented by an ovoid or round structure. Cochlea and cochlear vestibular neural structures are present
Cochlear hypoplasia (CH) Rudimentary otocyst Labyrinthine aplasia (Michel deformity) Name of the IEM
Inner ear malformations (IEM)
Table 1 Classification of inner ear malformations.
Cochlear aplasia
Common cavity
Incomplete partition (IP) of the cochlea
Large vestibular aqueduct Cochlear aperture syndrome (LVAS) abnormalities (CA)
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Cochlear hypoplasia (CH), a subgroup of IEM, also has four different types identified according to CT results. Radiological views of CH types are shown in Fig. 1. Cochlear hypoplasia type I (CH-I) is defined as a bud like cochlea (round or ovoid) arising from the internal acoustic canal (IAC). Internal architecture is severely deformed; no modiolus or interscalarsepta can be identified. There may or may not be a septum separating IAC from the cochlea. In the provided Fig. 1 (ISS), there is a thin septum separating the two structures. Cochlear hypoplasia type II (CH-II) is defined as cochlea with smaller dimensions and without modiolus and ISS. But external architecture is similar to that of a normal cochlea and makes a wide connection with the existing IAC. The vestibular aqueduct is enlarged, and the vestibule is minimally dilated. Cochlear hypoplasia type III (CH-III) has a shorter modiolus than normal and the cochlea has a reduced number of turns (<2 turns). Internal and external architecture are similar to normal cochlea, with smaller dimensions. The vestibule and semicircular canals are hypoplastic. Finally, cochlear hypoplasia type IV (CH-IV) has a cochlea with approximately a normal sized basal turn and severely hypoplastic middle and apical turns. The labyrinthine segment of the facial nerve may be located anterior to the cochlea. Fig. 2 shows a schematic view of CH types. CT and MR images and schematic view of CH types show difference. When the features of CH are evaluated histopathologically, it can be seen that there are very thin intersepta coming from the modiolus in schematic view. Unfortunately the resolution of HRCT and that of MRI are not precise enough for the present time, to detect these very rudimentary developments. Therefore, it is possible to evaluate these as completely cystic with the present day imaging modalities. But in future, we will most probably be able to detect these thin septa, with much developed imaging resolution. It was known that cochlear aperture (CA) and cochlear nerve (CN) status also show variability across IEM types [1,3]. On MRI; the diameters, area, and signal intensity of the CN were measured and compared to the ipsilateral facial nerve. Also the width of the CA was measured on axial images and it was defined as ‘stenotic’ when the width was less than 1.5 mm [5,6]. Some studies have investigated audiological findings of IEM but not according to types of IEM. The aim of the current study is to evaluate audiological and radiological findings of cochlear hypoplasia a subgroup of IEM. As described above, cochlear hypoplasia has four different types identified by Sennaroglu [1,2]. These CH groups are compared according to degree and type of hearing loss, status of CA and CN. 2. Materials and methods The current study was conducted at Hacettepe University, Department of Ear-Nose-Throat and Department of Audiology. Hacettepe University’s Non-invasive Ethical Committee approved this study (No: GO 14/195-30). In our IEM database, there were 481 subjects when this study conducted and 113 of them have CH diagnosis. Inclusion criteria
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Fig. 1. Radiological views of cochlear hypoplasia types. (A) Cochlear hypoplasia type I. (B) Cochlear hypoplasia type II. (C) Cochlear hypoplasia type III. (D) Cochlear hypoplasia type IV.
Fig. 2. Drawing of cochlear hypoplasia types. This figure used with permission of editor of Cochlear Implant International.
for the current study is having CH diagnosis in at least one ear and having both CT and MRI carried out in Hacettepe University’s, Radiology Department. For the audiological re-testing, 68 of them were reached; however, two subjects had a history of meningitis so they were excluded from the study. As a result, the current study included 66 subjects with 112 ears with CH. 2.1. Audiological evaluation Audiologic testing was done using a GSI 61 clinical audiometer with insert phones at frequencies 125–6000 Hz for air conduction thresholds and with bone oscillator at frequencies 500–1000–2000–4000 Hz for bone conduction. To decide air and bone conduction thresholds, age appropriate subjective test methods were used. For the pediatric group, Visual Reinforcement Audiometry (VRA) or Play Audiometry was used according to the chronological age and developmental status of the subjects. These tests applied for both air
conduction and bone conduction thresholds. For two children with accompanying syndromes (one of them also was one year of age), both air and bone conduction thresholds checked with Auditory Brainstem Response (ABR) testing was used to confirm the subjective test results. To check middle ear status, a GSI Tympstar was used with 226 Hz and 1000 Hz probe tones. Acoustic immittance and bone conduction threshold was used to confirm type of hearing loss, whether it is conductive, sensory-neural or mixed type. Hearing aid (HA) users were tested bilaterally; however cochlear implant (CI) and auditory brainstem implant (ABI) users were tested only on the contralateral side (without implant). Performance with hearing devices was not within the scope of this study. To decide degree of hearing loss, Clark’s (1981) classification, used by ASHA and our clinic, was used. Besides these seven groups, there was another group called ‘‘no response group’’. Subjects in this group did not have any behavioral response to auditory stimulation. For statistical analyses, these
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Fig. 3. Distribution of inner ear structures.
8 groups decreased into four groups to make analyses sensible. The first group integrates slight and mild hearing loss, the second group integrates moderate and moderately severe; the third group integrates severe and profound hearing loss. And the last group includes the ‘‘no response’’ group. 2.2. Radiological evaluation There were 113 patients with cochlear hypoplasia in our IEM database. Axial and coronal HRCT of the temporal bone were evaluated to categorize the malformation appropriately. The status of the CN was evaluated with axial and sagittal oblique T2 weighted MRI scans. CT and MRI of all subjects were performed in Department of Radiology of Hacettepe University. CT imaging was performed on a 4-channel multidetector CT scanner (Somatom Plus 4 Volume Zoom; Siemens, Erlangen, Germany) in the axial plane. The images were obtained with 0.5-mm collimation and 0.5-mm thickness. Reformatted axial images parallel to the lateral semicircular canal and coronal images were also created. MRI was performed with either a 3T (Magnetom Allegra, Siemens, or Ingenia, Philips) or a 1.5T scanner (Symphony, Siemens) by using a standard head coil. The standard temporal bone protocol included axial and sagittal oblique 3D-constructive interference in steady state (3D-CISS) or 3D DRIVE imaging. CA was measured at its midportion at the mid-modiolar level on the axial images and it was evaluated whether it was normal, stenotic or aplasic. In the MRI studies, the CN was evaluated on axial and especially on sagittal-oblique T2 weighted images and classified as aplastic, hypoplastic, or normal according to their size compared to ipsilateral facial nerve diameter.
hypoplasia and accompanying IEM, hearing loss type and degree, cochlear nerve and cochlear aperture status were done. To decide significance of analysis ‘‘chi-square’’ test was used. 3. Results 3.1. Descriptive statistics In the study, there were 66 (42 female and 24 male) subjects. In audiological examination, age range was from 12 months to 60 years 5 months (mean: 12 years 6 months). In audiological evaluation, age range was 11 months to 58 years 8 months with mean age 9 year 9 months. Subjects in the study have different syndromes; one Cri-du-chat syndrome, one Down syndrome, two Waardenburg syndromes, and two Goldenhar syndromes. Two subjects had craniofacial anomaly and 4 subjects had stapedectomy due to middle ear anomaly. Other analyses were conducted according to number of ears with CH. As a result, 132 ears were evaluated and 112 ears have CH diagnosis. 20 ears have different IEM types or normal cochlear structures. Fig. 3 shows IEM distribution of these ears. In the study, subjects differ in hearing aid usage, whether it is implantable or not. Some subjects need no hearing aid due to normal hearing or mild to moderate hearing loss on the contralateral ear (11 ears). In general, both CI and ABI users have one side implantation (related to social security protocols). Besides, most of the implanted subjects do not use contralateral hearing aids due to inadequate benefit. Table 2 shows hearing aid usage distribution across CH groups. In CHIV, there was no ABI user but there are CI users. However, the other three groups include hearing aid, CI and ABI users.
2.3. Statistical analysis
3.2. Cochlear hypoplasia and hearing loss
For statistical analysis, SPSS 21 was used. Descriptive statistics about frequencies, and distributions of cochlear
There were 112 ears with CH diagnosis, but implanted ears were excluded from hearing loss degree and type analysis. As a
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Table 2 Cochlear hypoplasia types and used amplifications. Amplification types No need to HA
HA
CI
ABI
No benefit from HA
CH-I CH-II CH-III CH-IV
0 2 3 3
4 1 18 7
4 8 10 2
3 7 6 0
8 9 14 3
Total
8
30
24
16
34
HA: hearing aid. CI: cochlear implant. ABI: auditory brainstem implant.
Table 3 Cochlear Hypoplasia Types and Hearing Loss. Type of hearing loss
CH-I N % CH-II N % CH-III N % CH-IV N % Total N %
Degree of hearing loss
Sensorineural
Mixed
Conductive
Mild
Moderate–moderately severe
Severe-profound
No response
12 85.71
2 14.29
0 0.00
0 0.00
1 7.10
8 57.10
5 35.70
13 92.86
1 7.14
0 0.00
0 0.00
2 14.30
8 57.10
4 28.60
34 85.00
6 15.00
0 0.00
0 0.00
4 10.00
26 65.00
10 25.00
5 38.46
6 46.15
2 15.38
1 7.70
6 46.20
6 46.20
0 0.00
64 79.01
15 18.52
2 2.47
1 1.20
13 16.00
48 59.30
19 23.50
result, degree of hearing loss in relation to type of malformation was determined on 81 ears. 9 patients went through cochlear or auditory brainstem implantation after audiological evaluation. Therefore, their preoperative test results were used in analysis. 3.2.1. Cochlear hypoplasia and degree of hearing loss There were four hearing loss (HL) groups as described in method. In CH-I, there were 14 ears with different HL degrees. 7.1% had moderate to moderately severe HL, 57.1% had severe to profound HL 35.7% had no response to sound. In CH-II, there were 14 ears; 14.3% had moderate to moderately severe HL, 57.1% had severe to profound HL and 28.6% had no response in subjective testing. In 40 ears with CH-III, there were moderate to moderately severe HL in 10% of them, severe to profound HL in 65% and no response in 25%. There were 13 ears with CH-IV, one ear had slight to mild HL (7.7%) in this group. 46.2% had moderate to moderately severe HL and 46.2% had severe to profound HL. CH types and degree of HL distribution are shown in Table 3. CH types were statistically significantly different in terms of hearing loss degree (p = 0.033 < p = 0.05). This difference was caused by CH-IV, since CH-I, CH-II and CH-III were not statistically significantly different from each other in terms of hearing loss degree. However, CH-IV was statistically
significantly different from the other three groups (p = 0.06; p = 0.26; p = 0.02 < p = 0.05). 3.2.2. Cochlear hypoplasia and type of hearing loss. In CH-I, 85.71% of ears had SNHL and 14.29% had mixed type HL. CHII included 92.86% SNHL and 7.14% mixed type HL. SNHL rate in CH-III was 85% and mixed type HL was 15%. In CH-IV group, SNHL rate was 38.46% and mixed type HL was 46.15% and pure conductive hearing loss (CHL) was 15.38%. There was no pure CHL in CH-I, CH-II and the CH-III groups (see Table 3). CH groups show a statistically significant difference from each other in terms of type of hearing loss (p = 0.010 < p = 0.05). This difference is caused by CH-IV and CH-IV differs from the other three groups statistically (p = 0.20; p = 0.06; p = 0.02 < p = 0.05). 3.3. Relationship between cochlear hypoplasia type, cochlear aperture and cochlear nerve Cochlear aperture and cochlear nerve showed differences according to CH type. In this study, 112 ears were evaluated with CH, 41.07% of them had normal cochlear aperture, 51.79% of them had cochlear aperture stenosis and 7.14% have
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Table 4 Cochlear hypoplasia types, status of cochlear aperture and cochlear nerve. Cochlear aperture
CH-I N % CH-II N % CH-III N % CH-IV N % Total N %
Cochlear nerve
Normal
Stenosis
Aplasia
Normal
Hypoplasia
Aplasia
4 21.10
12 63.20
3 15.80
4 21.05
7 36.84
8 42.11
6 22.20
20 74.10
1 3.70
8 29.63
10 37.04
9 33.33
24 47.10
23 45.10
4 7.80
21 41.18
15 29.41
15 29.41
12 80.00
3 20.00
0 0.00
13 86.67
2 13.33
0 0.00
46 41.10
58 51.80
8 7.10
46 41.07
34 30.36
32 28.57
Table 5 Relationship between cochlear nerve, cochlear aperture and degree of hearing loss. Degree of hearing loss
Cochlear aperture Normal Stenosis Aplasia Cochlear nerve Normal Hypoplasia Aplasia Total
Mild
Moderate–moderately severe
Severe-profound
No response
0 0.00 1 2.30 0 0.00
7 21.20 6 14.00 0 0.00
24 72.70 22 51.20 2 40.00
2 6.10 14 32.60 3 60.00
0 0.00 1 3.70 0 0.00 1 1.20
8 23.50 5 18.50 0 0.00 13 16.00
23 67.60 20 74.10 5 25.00 48 59.30
3 8.80 1 3.70 15 75.00 19 23.50
cochlear aperture aplasia. Only the CH-IV group had no cochlear aperture aplasia. However, the other three groups had at least one cochlear aperture aplasia. In the same way as with CA, CN status shows variance for each cochlear hypoplasia. When cochlear nerve status was examined, there were 41.07% normal cochlear nerves, 30.36% cochlear nerve hypoplasia and 28.57% cochlear nerve aphasias. Although there were cases with CN hypoplasia, there was no CN aplasia in the group CV-IV. Table 4 shows distribution of cochlear aperture and cochlear nerve according to type of cochlear hypoplasia. In terms of CA and CN status, the CH-IV group seems to be different from the other three groups but this was not approved statistically. 3.4. Relationship between hearing loss, cochlear aperture and cochlear nerve Cases with CA aplasia mostly had severe to profound HL or no response to sound. However, when there was CA stenosis,
HL degree shows more variability and there was one case with mild HL. Degree of HL changes from mild to profound in CA stenosis and some cases had no response. When we come to the normal CA, like with CA stenosis, this group includes all types of HL groups except mild HL. There is one case of CA stenosis with mild SNHL. This shows us that not all patients with CA stenosis are candidates for a CI. When we look at the relationship between CN and HL, the CN aplasia percentage was 24.7%; CN hypoplasia percentage was 33.3% and normal CN percentage was 42%. In the CN aplasia group, 25% of cases had severe to profound HL and 75% of cases had no response to sound. However CN hypoplasia groups show more variability in terms of HL degree. In subjects with normal CN, 23.5% of them had moderate to moderately severe HL, 67.6% had severe to profound HL and 8.8% had no response to sound. The normal CN group also had moderate to profound HL and this group also includes some cases with no response to sound. Table 5 summarizes cochlear nerve and cochlear aperture relations to hearing loss.
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When there is a CA aplasia, there is no normal cochlear nerve. However, when there is CA stenosis or normal CA, the condition of the CN shows variation between normal, hypoplasic and aplasic. 4. Discussion In the current study, four different cochlear hypoplasia types were evaluated according to their audiologic and radiologic findings. It has been noted that CH forms approximately 15% of IEM [7]. However, in our study, this percentage was higher at 23.5%. When we think of cochlear hypoplasia in itself, on retest of 112 ears, CH-III was found to form 45.5% of this CH group. CH-II rate was 24.1%; CH-I rate was 16.9% and CH-IV rate was 13.3%. Inner ear includes both hearing and balance organs. Embryologically all of these structures are derived from otic capsule and during development subset of cells dissociates from the otocyst [8]. If there is an arrest before the formation otocyst labyrinthine aplasia (Michel Aplasia) and any insult occurs at the beginning of the formation of the otocyst, this results in rudimentary otocyst deformity [9]. During the 4th week of gestation, these cells migrate between the epithelium of the otic vesicle and its basement membrane to form VIIIth nerve ganglion forms and if the arrest is at the end of the 4th week, common cavity occurs [9,10]. After the development of the otic vesicle at the end of the 4th week, the cochlea, the vestibule, and the endolymphatic duct are formed from the membranous labyrinth. If there is any insult during the 5th week, cochlear aplasia occurs. Gulya reports that the cochlear duct forms as a tubular diverticulum from the saccular portion of the otic vesicle in the 6-week embryo. This ventral projection coils with medial growth, completing one turn by the 6th week and its entire two and one-half turns by the 8th week. And also, development of the membranous labyrinth starts from the basal turn and advances to the apex within 2 weeks and completed two and one-half turns by the 8- to 10-week stage [10]. The occurrence of cochlear hypoplasia should be related to any arrest in between 6th and 8th weeks, except CH-IV. Since CHIV shows a normal sized basal turn with hypoplastic middle and apical turns, the insult should be happened during the 10th and 20th weeks. This means that the basal turn reaches its full size, and the middle and apical turns could not develop to their final size [9]. Erixon report that cochlea length shows variations among normal individuals [11]. Sennaroglu stated that for cochlear hypoplasia, minimum limit could be use as a starting point and also cochlea with a small basal turn and a small apical turn is regarded as hypoplastic [9]. Some types of hypoplastic cochlea (CH-III and CH-IV) have dimensions less than the inferior limit of normal cases. For CH-I and CH-II, in addition to arrest in size of cochlea, there is a developmental arrest in internal structures. Since the outline of the CH-II is more similar to normal cochlea, it could be inferred that CH-II is better developed than CH-I [9]. Bilateral or unilateral IEMs have been reported in literature [4,12]. Masuda et al. reported that prevalence of inner ear or internal acoustic canal malformation in children with unilateral SNHL under one year of age was significantly higher than
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children, with unilateral SNHL, over 1–15 years of age [13]. In the current study, subjects with unilateral CH are accompanied by normal cochlea and also other types of IEM. As mentioned earlier developmental arrest is crucial in occurrence of IEM, besides this the vestibulocochlear artery supplies are also important, especially in unilateral and coexistent pathologies [9]. In this study, incomplete partition type-I (IP-I) was the most common accompanying malformation for CH. Others were common cavity, Michel deformity and cochlear aplasia. Sennaroglu explained this co-occurrence of CH and IP-I with vascular supply [9]. In the literature, there are some studies related to audiologic results of IEM and most of the studies focus on such patient’s performance after CI or ABI. Coticchia evaluated the radiological findings of 69 subjects with SNHL and found 17 subjects with IEM. 14 subjects participated in the study, 2 had profound HL, 4 had severe HL, 7 moderate HL and one subject had mild HL [14]. However, the type of IEM was not stated. Bamiou re-evaluated radiological results and audiological testing was done again on 35 subjects with unilateral HL. They reported there were 12 subjects with IEM and internal acoustic meatus anomaly [15]. In the same way as the previous study, they also did not mention the type of IEM. Different from these studies, the current study focuses especially on the CH subgroup of IEM and tries to describe audiological results according to four different types of CH. It was found that HL shows variation according to types of CH. In the CH-I, CH-II and CH-III groups, HL varies from moderate to profound and also some cases had no response to sound on subjective testing. However, the CH-IV group had mild HL to profound HL and also all cases in this group had responses to sound at subjective testing. In embryological development, any arrest in 6th and 8th week, could result in CH-I, CH-II and CH-II, except CH-IV. Since basal turn is present in CH-IV, insult should be in 10th and 20th week. It could be inferred that latest insult produces the better hearing sensitivity. In this aspect the CH-IV group is significantly different from the other three groups of CH. When we look at types of HL in CH, 79.1% was SNHL, 18.52% was mixed type HL and 2.47% was CHL. The rate of SNHL is similar on across the CH-I, CH-II and CH-III groups and there was no pure CHL but some cases had mixed HL. However, only the CH-IV group includes pure conductive HL besides SN and mixed type HL. The CH-IV group also differs significantly from other three groups. Mixed type HL is more concentrated in the CH-III group. In this study, there were 4 cases with stapedectomy, 2 of them had CH-IV and the other two CH-III. At this point it is important to check radiological results in terms of middle ear malformations in the presence of IEM. Sennaroglu reported some differences in histopathology of IEM. There were 8 specimens with stapes fixation and 6 of them had CH (2 CH-I, 3 CH-II and one CH-III). There were also 6 specimens with oval window aplasia and 5 of them had CH (1 CH-I, 1 CH-II and 3 CH-III). The stapes is a part of the otic capsule and if there is an arrest of otic capsule development before the formation of the footplate, it is natural that the stapes will become fixed to the oval window [9]. As a result of this stapes fixation, conductive or mixed type HL is expected. In the current study, there were subjects with CHL that had
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stapedectomy. After stapedectomy, their thresholds improved and they were able to make better use of hearing aids. In the current study, all subjects’ radiological results were reviewed to check for CH type, CA and CN status. It has been reported that when there is IEM, it is possible to have cochlear aperture stenosis [2]. In this study, 51.79% of cases with CH had CA stenosis, 41.07% of cases had normal CA and 7.14% had CA aplasia. Aplasia of CA was present in the CH-I, CH-II and CH-III groups. However, there was no CA aplasia and mostly normal CA in the CH-IV group. CA stenosis is more concentrated in the CH-I and CH-II groups. Similar to the CHIV group, CH-III group also mostly has normal CA. In the same way with CA, CN also differs according to CH type. It was reported that CN hypoplasia and aplasia could accompany CH [3,16,17]. However, in the current study, the rate of normal CN was higher than in CN hypoplasia or aplasia in CH. In the CHIII group, the normal CN rate was highest but in CH-I, the CN aplasia rate was highest. In CH-I, CH-II and CH-III groups, there was CN aplasia but in the CH-IV group there were no case with CN aplasia. It is known that the status of the CN directly affects hearing and as a result aplasia of the CN can cause profound HL, but hypoplasia of the CN could be related to residual hearing [17]. In this study, hearing loss variation in the CH-IV group was mild to profound and this could be related to the status of the CN since there was no aplasia of CN in this group. In this study, hearing device types showed variability across the CH groups. Hearing aids, CI and ABI were used. Also, there was a group of cases not using any hearing device due to presence of normal hearing on the contralateral side; some others did not use a device due to limited or no benefit from hearing aids. In Turkey, CI or ABI applications are single sided due to non-reimbursement of bilateral implants. CI or ABI users mostly do not use a HA on the contralateral side due to insufficient benefit. In the study group, 28 cases use CI and 20 cases use ABI. While choosing a device IEM, CA, CN and residual hearing should be taken into consideration. Especially, in cases with CN hypoplasia it is difficult to decide between CI and ABI [2,18–22]. In the presence of hypoplastic CN, bilateral CI or ABI after removal of the CI electrode was used as an option for amplification [23,24]. In our study group, 5 cases use bimodal stimulation, CI on one side and ABI on the contralateral side. However, details of bimodal stimulation were not within the scope of this study. Also in our study, there is one case with mild HL and five cases with moderate to moderately severe HL in the presence of CN hypoplasia. Similar to our findings, Taiji reported 6 children with mild and moderate SNHL with CN hypoplasia [25] and some cases with normal CN had no response to sound in subjective testing. It could be inferred from this finding that for residual hearing just having a normal CN is not enough; hearing is the result of the total effect of cochlea, cochlear aperture and cochlear nerve. 5. Conclusion This study demonstrates that CH shows variability in terms of degree and type of HL and also CA and CN status. Other IEM types, especially IP-I, may accompany CH. The most common
type of cochlear hypoplasia in this study is CH-III. In general the CH-IV subgroup was statistically, significantly different from the other three CH groups. In the CH-IV group, there was mild HL, and all subjects with CH-IV had responses to sound. Pure conductive HL was present in only this CH-IV group. Also there was no case of CA or CN aplasia in CH-IV group and as a result there was no ABI user. It seems that even within the same subgroup of CH, HL degree and type have great variability. While evaluating radiological findings, both IEM and middle ear malformation should be taken into consideration. In our study, when there was conductive or mixed type of HL in the presence of CH, just for these cases CT results were reevaluated to check for middle ear malformation. However, the subjects with SNHL also should be re-evaluated for presence of middle ear malformations. This could be accepted as a limitation for this study. Conflict of interest There is no conflict of interest. Acknowledgements For this study, no outside found or grants were received. This study is based on first author’s doctoral dissertation. References [1] Sennaroglu L. Cochlear implantation in inner ear malformations – a review article. Cochlear Implants Int 2010;11:4–41. [2] Sennaroglu L, Sennaroglu G, Atay G. Auditory brainstem implantation in children. Curr Otorhinolaryngol Rep 2013;1:80–91. [3] Sennaroglu L, Ozkan HB, Aslan F. Impact of cochleovestibular malformations in treating children with hearing loss. Audiol Neurotol 2013;18(Suppl. 1):3–31. [4] Sennaroglu L, Saatci I. A new classification for cochleovestibular malformations. Laryngoscope 2002;112:2230–41. [5] Cho SW, Kang SI, Park SJ. Clinical characteristics of patients with narrow bony cochlear nerve canal: is the bilateral case just a duplicate of the unilateral case? Laryngoscope 2013;123:1996–2000. [6] Stjernholm C, Muren C. Dimensions of the cochlear nerve canal: a radioanatomic investigation. Acta Otolaryngol 2002;122:43–8. [7] Joshi VM, Navlekar SK, Kishore GR, Reddy KJ, Kumar ECV. CT and MR imaging of the inner ear and brain in children with congenital sensorineural hearing loss. RadioGraphics 2012;32:683–98. [8] Mann ZF, Kelley MW. Development of the inner ear. In: Moody SA, editor. Principles of developmental genetics. 2nd ed., USA: Elsevier Science & Technology Books; 2014. p. 377–91. [9] Sennaroglu L. Histopathology of inner ear malformations: do we have enough evidence to explain pathophysiology? Cochlear Implants Int 2016. [10] Gulya AJ. In: Gulya AJ, editor. Gulya and Schuknecht’s anatomy of the temporal bone with surgical implications. 3rd ed., New York, USA: Taylor & Francis Group; 2007. 376 pp. [11] Erixon E, Ho¨gstorp H, Wadin K, Rask-Andersen H. Variational anatomy of the human cochlea: implications for cochlear implantation. Otol Neurotol 2009;14–22. [12] Bartel-Friedrich S, Wulke C. Classification and diagnosis of ear malformations. GMS Curr Top Otorhinolaryngol Head Neck Surg 2007;6. [13] Masuda S, Usui S, Matsunaga T. High prevalence of inner-ear and/or internal auditory canal malformations in children with unilateral sensorineural hearing loss. Int J Pediatr Otorhinolaryngol 2013;77: 228–32.
Please cite this article in press as: Cinar BC, et al. Audiologic and radiologic findings in cochlear hypoplasia. Auris Nasus Larynx (2017), http:// dx.doi.org/10.1016/j.anl.2016.12.002
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ANL-2220; No. of Pages 9 B.C. Cinar et al. / Auris Nasus Larynx xxx (2016) xxx–xxx [14] Coticchia JM, Gokhale A, Waltonen J, Sumer B. Characteristics of sensorineural hearing loss in children with inner ear anomalies. Otolaryngol Head Neck Surg 2006;27:33–8. [15] Bamiou DE, Savy L, O’ Mahoney C, Phelps P, Srimanna T. Unilateral sensorineural hearing loss and its aetiology in childhood: the contribution of computerised tomography in aetiological diagnosis and management. Int J Pediatr Otorhinolaryngol 1999;51:91–9. [16] Puram S, Tward AD, Jung DH, Dilger AE, Herrmann BS, Duhaime AC, et al. Auditory brainstem implantation in a 16-month-old boy with cochlear hypoplasia. Otol Neurotol 2014;36:618–24. [17] Li Y, Yang J, Liu J, Wu H. Restudy of malformations of the internal auditory meatus, cochlear nerve canal and cochlear nerve. Eur Arch Otorhinolaryngol 2014. [18] Sennaroglu L, Colleti V, Manrique M, Laszig R, Offeciers E, Saeed S, et al. Auditory brainstem implantation in children and non-neurofibromatosis type 2 patients: a consensus statement. Otol Neurotol 2011;32:187–91. [19] Govaerts PJ, Casselman J, Daemers K, Beukelaer CD, Yperman M, Ceulaer GD. Cochlear implants in aplasia and hypoplasia of the cochleovestibular nerve. Otol Neurotol 2003;24:887–91.
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[20] Young N, Kim FM, Ryan ME, Tournis E, Yaras S. Pediatric cochlear implantation of children with eighth nerve deficiency. Int J Pediatr Otorhinolaryngol 2012;76:1442–8. [21] Bradley J, Bell M, Beale T, Graham JM. Variable long term outcomes from cochlear implantation in children with hypoplastic auditory nerves. Cochlear Implants Int 2008;9:34–60. [22] Colletti L, Colletti G, Mandala M, Colletti V. The therapeutic dilemma of cochlear nerve deficiency: cochlear or brainstem implantation? Otolaryngol Head Neck Surg 2014;151:308–14. [23] Oker N, Loundon N, Marlin S, Rouillon I, Leboulanger N, Garabe´dian EN. Bilateral implantation in children with cochleovestibular nerve hypoplasia. Int J Pediatr Otorhinolaryngol 2009;73. [24] Colletti L, Wilkinson EP, Colletti V. Auditory brainstem implantation after unsuccessful cochlear implantation of children with clinical diagnosis of cochlear nerve deficiency. Ann Otol Rhinol Laryngol 2013;122:605–12. [25] Taiji H, Morimoto N, Matsunaga T. Unilateral cochlear nerve hypoplasia in children with mild to moderate hearing loss. Acta OtoLaryngol 2012;132:1160–7.
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ANL-2220; No. of Pages 9 Auris Nasus Larynx xxx (2016) xxx–xxx Contents lists available at ScienceDirect
Auris Nasus Larynx journal homepage: www.elsevier.com/locate/anl
Audiologic and radiologic findings in cochlear hypoplasia Betul Cicek Cinar a,*, Merve Ozbal Batuk a, Emel Tahir b, Gonca Sennaroglu a, Levent Sennaroglu c a
Department of Audiology, Hacettepe University, Ankara, Turkey ˇˇ is¸kapˇˇ i Yˇˇidˇˇirˇˇim Beyazˇˇit Research and Training Hospital, Ankara, Turkey Ear-Nose-Throat Clinic, D c Department of Otolaryngology, Head and Neck Surgery, Hacettepe University, Ankara, Turkey b
A R T I C L E I N F O
A B S T R A C T
Article history: Received 12 July 2016 Accepted 19 December 2016 Available online xxx
Objective: The aim of the current study is to evaluate audiologic and radiologic findings of cochlear hypoplasia which is a subgroup of inner ear malformations. Methods: This study was a prospective clinical study and based on voluntary participation from cases with cochlear hypoplasia diagnosis. The study was conducted at Hacettepe University, Department of Otolaryngology, Head and Neck Surgery and Department of Audiology. Subjects were selected from an inner ear malformations database. Inclusion criteria were having cochlear hypoplasia for at least one ear. There were 66 subjects with an age range of 12 months and 60 years 5 months. For each subject, pure tone audiometry and tympanometry were applied according to chronological and cognitive age. And also, auditory brainstem response test was applied to when it is need. Subjects’ radiologic results were reevaluated to confirm cochlear hypoplasia, cochlear nerve and cochlear aperture. Results: Cochlear hypoplasia types were statistically significantly different in terms of HL degree. This difference was caused by cochlear hypoplasia type IV group being was statistically different from the other three groups. Like with degree of HL, cochlear hypoplasia groups were statistically different from other three groups in terms of type of hearing loss. Cochlear aperture and cochlear nerve status showed variation according to cochlear hypoplasia type but these differences were not statistically approved. Conclusions: In the current study, incidence of cochlear hypoplasia was 23.5% in all inner ear malformation. With this study, it was seen that subtypes of cochlear hypoplasia showed variability in terms of degree and type of hearing loss and also cochlear aperture and cochlear nerve status. Especially cochlear hypoplasia type IV differs from other three cochlear hypoplasia types. ß 2016 Elsevier Ireland Ltd. All rights reserved.
Keywords: Audiological evaluation Inner ear malformation Cochlear hypoplasia Cochlear aperture Cochlear nerve Cochlear implantation
1. Introduction Inner ear malformations (IEMs) are the cause of congenital sensorineural hearing loss in approximately 20% of hearing impaired children [1]. IEM is used as a general term for all cochlea types that differ from normal
¨ niversitesi, Sag˘lık Bilimleri Faku¨ltesi, * Corresponding author at: Hacettepe U Odyoloji Bo¨lu¨mu¨ Sıhhiye, Ankara 06100, Turkey. E-mail address: [email protected] (B.C. Cinar).
structures. Sennaroglu et al. classified IEM by using computerized tomography (CT) and magnetic resonance imaging (MRI) [1,2]. This latest classification includes eight groups; labyrinthine aplasia (Michel deformity), rudimentary otocyst, cochlear aplasia, common cavity, incomplete partition (IP) of the cochlea (IP), cochlear hypoplasia (CH), large vestibular aqueduct syndrome (LVAS) and cochlear aperture abnormalities (CA) [2]. All these groups show variability in terms of radiological findings [1,3,4]. The latest classification is summarized in Table 1.
http://dx.doi.org/10.1016/j.anl.2016.12.002 0385-8146/ß 2016 Elsevier Ireland Ltd. All rights reserved.
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ANL-2220; No. of Pages 9 B.C. Cinar et al. / Auris Nasus Larynx xxx (2016) xxx–xxx Cochlear aperture or cochlear nerve canal transmits the cochlear nerve from the Internal acoustic canal to the cochlea An enlarged vestibular aqueduct in the presence of a normal cochlea, vestibule and semicircular canals External dimensions are reduced relative to the normal cochlea. According to internal architecture, four different types of CH: CH-I, CH-II, CH-III and CH-IV External dimensions are similar to normal cochleae but the internal architecture is deficient. Three different types: (IP-I), incomplete (IP-II) and (IP-III) Short The cochlea, vestibule, explanations semicircular canals, vestibular and cochlear aqueducts are absent
Incomplete millimetric The cochlea representations of otic is absent capsule (round or ovoid in shape), without an internal auditory canal
Cochlea and vestibule are represented by an ovoid or round structure. Cochlea and cochlear vestibular neural structures are present
Cochlear hypoplasia (CH) Rudimentary otocyst Labyrinthine aplasia (Michel deformity) Name of the IEM
Inner ear malformations (IEM)
Table 1 Classification of inner ear malformations.
Cochlear aplasia
Common cavity
Incomplete partition (IP) of the cochlea
Large vestibular aqueduct Cochlear aperture syndrome (LVAS) abnormalities (CA)
2
Cochlear hypoplasia (CH), a subgroup of IEM, also has four different types identified according to CT results. Radiological views of CH types are shown in Fig. 1. Cochlear hypoplasia type I (CH-I) is defined as a bud like cochlea (round or ovoid) arising from the internal acoustic canal (IAC). Internal architecture is severely deformed; no modiolus or interscalarsepta can be identified. There may or may not be a septum separating IAC from the cochlea. In the provided Fig. 1 (ISS), there is a thin septum separating the two structures. Cochlear hypoplasia type II (CH-II) is defined as cochlea with smaller dimensions and without modiolus and ISS. But external architecture is similar to that of a normal cochlea and makes a wide connection with the existing IAC. The vestibular aqueduct is enlarged, and the vestibule is minimally dilated. Cochlear hypoplasia type III (CH-III) has a shorter modiolus than normal and the cochlea has a reduced number of turns (<2 turns). Internal and external architecture are similar to normal cochlea, with smaller dimensions. The vestibule and semicircular canals are hypoplastic. Finally, cochlear hypoplasia type IV (CH-IV) has a cochlea with approximately a normal sized basal turn and severely hypoplastic middle and apical turns. The labyrinthine segment of the facial nerve may be located anterior to the cochlea. Fig. 2 shows a schematic view of CH types. CT and MR images and schematic view of CH types show difference. When the features of CH are evaluated histopathologically, it can be seen that there are very thin intersepta coming from the modiolus in schematic view. Unfortunately the resolution of HRCT and that of MRI are not precise enough for the present time, to detect these very rudimentary developments. Therefore, it is possible to evaluate these as completely cystic with the present day imaging modalities. But in future, we will most probably be able to detect these thin septa, with much developed imaging resolution. It was known that cochlear aperture (CA) and cochlear nerve (CN) status also show variability across IEM types [1,3]. On MRI; the diameters, area, and signal intensity of the CN were measured and compared to the ipsilateral facial nerve. Also the width of the CA was measured on axial images and it was defined as ‘stenotic’ when the width was less than 1.5 mm [5,6]. Some studies have investigated audiological findings of IEM but not according to types of IEM. The aim of the current study is to evaluate audiological and radiological findings of cochlear hypoplasia a subgroup of IEM. As described above, cochlear hypoplasia has four different types identified by Sennaroglu [1,2]. These CH groups are compared according to degree and type of hearing loss, status of CA and CN. 2. Materials and methods The current study was conducted at Hacettepe University, Department of Ear-Nose-Throat and Department of Audiology. Hacettepe University’s Non-invasive Ethical Committee approved this study (No: GO 14/195-30). In our IEM database, there were 481 subjects when this study conducted and 113 of them have CH diagnosis. Inclusion criteria
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Fig. 1. Radiological views of cochlear hypoplasia types. (A) Cochlear hypoplasia type I. (B) Cochlear hypoplasia type II. (C) Cochlear hypoplasia type III. (D) Cochlear hypoplasia type IV.
Fig. 2. Drawing of cochlear hypoplasia types. This figure used with permission of editor of Cochlear Implant International.
for the current study is having CH diagnosis in at least one ear and having both CT and MRI carried out in Hacettepe University’s, Radiology Department. For the audiological re-testing, 68 of them were reached; however, two subjects had a history of meningitis so they were excluded from the study. As a result, the current study included 66 subjects with 112 ears with CH. 2.1. Audiological evaluation Audiologic testing was done using a GSI 61 clinical audiometer with insert phones at frequencies 125–6000 Hz for air conduction thresholds and with bone oscillator at frequencies 500–1000–2000–4000 Hz for bone conduction. To decide air and bone conduction thresholds, age appropriate subjective test methods were used. For the pediatric group, Visual Reinforcement Audiometry (VRA) or Play Audiometry was used according to the chronological age and developmental status of the subjects. These tests applied for both air
conduction and bone conduction thresholds. For two children with accompanying syndromes (one of them also was one year of age), both air and bone conduction thresholds checked with Auditory Brainstem Response (ABR) testing was used to confirm the subjective test results. To check middle ear status, a GSI Tympstar was used with 226 Hz and 1000 Hz probe tones. Acoustic immittance and bone conduction threshold was used to confirm type of hearing loss, whether it is conductive, sensory-neural or mixed type. Hearing aid (HA) users were tested bilaterally; however cochlear implant (CI) and auditory brainstem implant (ABI) users were tested only on the contralateral side (without implant). Performance with hearing devices was not within the scope of this study. To decide degree of hearing loss, Clark’s (1981) classification, used by ASHA and our clinic, was used. Besides these seven groups, there was another group called ‘‘no response group’’. Subjects in this group did not have any behavioral response to auditory stimulation. For statistical analyses, these
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Fig. 3. Distribution of inner ear structures.
8 groups decreased into four groups to make analyses sensible. The first group integrates slight and mild hearing loss, the second group integrates moderate and moderately severe; the third group integrates severe and profound hearing loss. And the last group includes the ‘‘no response’’ group. 2.2. Radiological evaluation There were 113 patients with cochlear hypoplasia in our IEM database. Axial and coronal HRCT of the temporal bone were evaluated to categorize the malformation appropriately. The status of the CN was evaluated with axial and sagittal oblique T2 weighted MRI scans. CT and MRI of all subjects were performed in Department of Radiology of Hacettepe University. CT imaging was performed on a 4-channel multidetector CT scanner (Somatom Plus 4 Volume Zoom; Siemens, Erlangen, Germany) in the axial plane. The images were obtained with 0.5-mm collimation and 0.5-mm thickness. Reformatted axial images parallel to the lateral semicircular canal and coronal images were also created. MRI was performed with either a 3T (Magnetom Allegra, Siemens, or Ingenia, Philips) or a 1.5T scanner (Symphony, Siemens) by using a standard head coil. The standard temporal bone protocol included axial and sagittal oblique 3D-constructive interference in steady state (3D-CISS) or 3D DRIVE imaging. CA was measured at its midportion at the mid-modiolar level on the axial images and it was evaluated whether it was normal, stenotic or aplasic. In the MRI studies, the CN was evaluated on axial and especially on sagittal-oblique T2 weighted images and classified as aplastic, hypoplastic, or normal according to their size compared to ipsilateral facial nerve diameter.
hypoplasia and accompanying IEM, hearing loss type and degree, cochlear nerve and cochlear aperture status were done. To decide significance of analysis ‘‘chi-square’’ test was used. 3. Results 3.1. Descriptive statistics In the study, there were 66 (42 female and 24 male) subjects. In audiological examination, age range was from 12 months to 60 years 5 months (mean: 12 years 6 months). In audiological evaluation, age range was 11 months to 58 years 8 months with mean age 9 year 9 months. Subjects in the study have different syndromes; one Cri-du-chat syndrome, one Down syndrome, two Waardenburg syndromes, and two Goldenhar syndromes. Two subjects had craniofacial anomaly and 4 subjects had stapedectomy due to middle ear anomaly. Other analyses were conducted according to number of ears with CH. As a result, 132 ears were evaluated and 112 ears have CH diagnosis. 20 ears have different IEM types or normal cochlear structures. Fig. 3 shows IEM distribution of these ears. In the study, subjects differ in hearing aid usage, whether it is implantable or not. Some subjects need no hearing aid due to normal hearing or mild to moderate hearing loss on the contralateral ear (11 ears). In general, both CI and ABI users have one side implantation (related to social security protocols). Besides, most of the implanted subjects do not use contralateral hearing aids due to inadequate benefit. Table 2 shows hearing aid usage distribution across CH groups. In CHIV, there was no ABI user but there are CI users. However, the other three groups include hearing aid, CI and ABI users.
2.3. Statistical analysis
3.2. Cochlear hypoplasia and hearing loss
For statistical analysis, SPSS 21 was used. Descriptive statistics about frequencies, and distributions of cochlear
There were 112 ears with CH diagnosis, but implanted ears were excluded from hearing loss degree and type analysis. As a
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Table 2 Cochlear hypoplasia types and used amplifications. Amplification types No need to HA
HA
CI
ABI
No benefit from HA
CH-I CH-II CH-III CH-IV
0 2 3 3
4 1 18 7
4 8 10 2
3 7 6 0
8 9 14 3
Total
8
30
24
16
34
HA: hearing aid. CI: cochlear implant. ABI: auditory brainstem implant.
Table 3 Cochlear Hypoplasia Types and Hearing Loss. Type of hearing loss
CH-I N % CH-II N % CH-III N % CH-IV N % Total N %
Degree of hearing loss
Sensorineural
Mixed
Conductive
Mild
Moderate–moderately severe
Severe-profound
No response
12 85.71
2 14.29
0 0.00
0 0.00
1 7.10
8 57.10
5 35.70
13 92.86
1 7.14
0 0.00
0 0.00
2 14.30
8 57.10
4 28.60
34 85.00
6 15.00
0 0.00
0 0.00
4 10.00
26 65.00
10 25.00
5 38.46
6 46.15
2 15.38
1 7.70
6 46.20
6 46.20
0 0.00
64 79.01
15 18.52
2 2.47
1 1.20
13 16.00
48 59.30
19 23.50
result, degree of hearing loss in relation to type of malformation was determined on 81 ears. 9 patients went through cochlear or auditory brainstem implantation after audiological evaluation. Therefore, their preoperative test results were used in analysis. 3.2.1. Cochlear hypoplasia and degree of hearing loss There were four hearing loss (HL) groups as described in method. In CH-I, there were 14 ears with different HL degrees. 7.1% had moderate to moderately severe HL, 57.1% had severe to profound HL 35.7% had no response to sound. In CH-II, there were 14 ears; 14.3% had moderate to moderately severe HL, 57.1% had severe to profound HL and 28.6% had no response in subjective testing. In 40 ears with CH-III, there were moderate to moderately severe HL in 10% of them, severe to profound HL in 65% and no response in 25%. There were 13 ears with CH-IV, one ear had slight to mild HL (7.7%) in this group. 46.2% had moderate to moderately severe HL and 46.2% had severe to profound HL. CH types and degree of HL distribution are shown in Table 3. CH types were statistically significantly different in terms of hearing loss degree (p = 0.033 < p = 0.05). This difference was caused by CH-IV, since CH-I, CH-II and CH-III were not statistically significantly different from each other in terms of hearing loss degree. However, CH-IV was statistically
significantly different from the other three groups (p = 0.06; p = 0.26; p = 0.02 < p = 0.05). 3.2.2. Cochlear hypoplasia and type of hearing loss. In CH-I, 85.71% of ears had SNHL and 14.29% had mixed type HL. CHII included 92.86% SNHL and 7.14% mixed type HL. SNHL rate in CH-III was 85% and mixed type HL was 15%. In CH-IV group, SNHL rate was 38.46% and mixed type HL was 46.15% and pure conductive hearing loss (CHL) was 15.38%. There was no pure CHL in CH-I, CH-II and the CH-III groups (see Table 3). CH groups show a statistically significant difference from each other in terms of type of hearing loss (p = 0.010 < p = 0.05). This difference is caused by CH-IV and CH-IV differs from the other three groups statistically (p = 0.20; p = 0.06; p = 0.02 < p = 0.05). 3.3. Relationship between cochlear hypoplasia type, cochlear aperture and cochlear nerve Cochlear aperture and cochlear nerve showed differences according to CH type. In this study, 112 ears were evaluated with CH, 41.07% of them had normal cochlear aperture, 51.79% of them had cochlear aperture stenosis and 7.14% have
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Table 4 Cochlear hypoplasia types, status of cochlear aperture and cochlear nerve. Cochlear aperture
CH-I N % CH-II N % CH-III N % CH-IV N % Total N %
Cochlear nerve
Normal
Stenosis
Aplasia
Normal
Hypoplasia
Aplasia
4 21.10
12 63.20
3 15.80
4 21.05
7 36.84
8 42.11
6 22.20
20 74.10
1 3.70
8 29.63
10 37.04
9 33.33
24 47.10
23 45.10
4 7.80
21 41.18
15 29.41
15 29.41
12 80.00
3 20.00
0 0.00
13 86.67
2 13.33
0 0.00
46 41.10
58 51.80
8 7.10
46 41.07
34 30.36
32 28.57
Table 5 Relationship between cochlear nerve, cochlear aperture and degree of hearing loss. Degree of hearing loss
Cochlear aperture Normal Stenosis Aplasia Cochlear nerve Normal Hypoplasia Aplasia Total
Mild
Moderate–moderately severe
Severe-profound
No response
0 0.00 1 2.30 0 0.00
7 21.20 6 14.00 0 0.00
24 72.70 22 51.20 2 40.00
2 6.10 14 32.60 3 60.00
0 0.00 1 3.70 0 0.00 1 1.20
8 23.50 5 18.50 0 0.00 13 16.00
23 67.60 20 74.10 5 25.00 48 59.30
3 8.80 1 3.70 15 75.00 19 23.50
cochlear aperture aplasia. Only the CH-IV group had no cochlear aperture aplasia. However, the other three groups had at least one cochlear aperture aplasia. In the same way as with CA, CN status shows variance for each cochlear hypoplasia. When cochlear nerve status was examined, there were 41.07% normal cochlear nerves, 30.36% cochlear nerve hypoplasia and 28.57% cochlear nerve aphasias. Although there were cases with CN hypoplasia, there was no CN aplasia in the group CV-IV. Table 4 shows distribution of cochlear aperture and cochlear nerve according to type of cochlear hypoplasia. In terms of CA and CN status, the CH-IV group seems to be different from the other three groups but this was not approved statistically. 3.4. Relationship between hearing loss, cochlear aperture and cochlear nerve Cases with CA aplasia mostly had severe to profound HL or no response to sound. However, when there was CA stenosis,
HL degree shows more variability and there was one case with mild HL. Degree of HL changes from mild to profound in CA stenosis and some cases had no response. When we come to the normal CA, like with CA stenosis, this group includes all types of HL groups except mild HL. There is one case of CA stenosis with mild SNHL. This shows us that not all patients with CA stenosis are candidates for a CI. When we look at the relationship between CN and HL, the CN aplasia percentage was 24.7%; CN hypoplasia percentage was 33.3% and normal CN percentage was 42%. In the CN aplasia group, 25% of cases had severe to profound HL and 75% of cases had no response to sound. However CN hypoplasia groups show more variability in terms of HL degree. In subjects with normal CN, 23.5% of them had moderate to moderately severe HL, 67.6% had severe to profound HL and 8.8% had no response to sound. The normal CN group also had moderate to profound HL and this group also includes some cases with no response to sound. Table 5 summarizes cochlear nerve and cochlear aperture relations to hearing loss.
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When there is a CA aplasia, there is no normal cochlear nerve. However, when there is CA stenosis or normal CA, the condition of the CN shows variation between normal, hypoplasic and aplasic. 4. Discussion In the current study, four different cochlear hypoplasia types were evaluated according to their audiologic and radiologic findings. It has been noted that CH forms approximately 15% of IEM [7]. However, in our study, this percentage was higher at 23.5%. When we think of cochlear hypoplasia in itself, on retest of 112 ears, CH-III was found to form 45.5% of this CH group. CH-II rate was 24.1%; CH-I rate was 16.9% and CH-IV rate was 13.3%. Inner ear includes both hearing and balance organs. Embryologically all of these structures are derived from otic capsule and during development subset of cells dissociates from the otocyst [8]. If there is an arrest before the formation otocyst labyrinthine aplasia (Michel Aplasia) and any insult occurs at the beginning of the formation of the otocyst, this results in rudimentary otocyst deformity [9]. During the 4th week of gestation, these cells migrate between the epithelium of the otic vesicle and its basement membrane to form VIIIth nerve ganglion forms and if the arrest is at the end of the 4th week, common cavity occurs [9,10]. After the development of the otic vesicle at the end of the 4th week, the cochlea, the vestibule, and the endolymphatic duct are formed from the membranous labyrinth. If there is any insult during the 5th week, cochlear aplasia occurs. Gulya reports that the cochlear duct forms as a tubular diverticulum from the saccular portion of the otic vesicle in the 6-week embryo. This ventral projection coils with medial growth, completing one turn by the 6th week and its entire two and one-half turns by the 8th week. And also, development of the membranous labyrinth starts from the basal turn and advances to the apex within 2 weeks and completed two and one-half turns by the 8- to 10-week stage [10]. The occurrence of cochlear hypoplasia should be related to any arrest in between 6th and 8th weeks, except CH-IV. Since CHIV shows a normal sized basal turn with hypoplastic middle and apical turns, the insult should be happened during the 10th and 20th weeks. This means that the basal turn reaches its full size, and the middle and apical turns could not develop to their final size [9]. Erixon report that cochlea length shows variations among normal individuals [11]. Sennaroglu stated that for cochlear hypoplasia, minimum limit could be use as a starting point and also cochlea with a small basal turn and a small apical turn is regarded as hypoplastic [9]. Some types of hypoplastic cochlea (CH-III and CH-IV) have dimensions less than the inferior limit of normal cases. For CH-I and CH-II, in addition to arrest in size of cochlea, there is a developmental arrest in internal structures. Since the outline of the CH-II is more similar to normal cochlea, it could be inferred that CH-II is better developed than CH-I [9]. Bilateral or unilateral IEMs have been reported in literature [4,12]. Masuda et al. reported that prevalence of inner ear or internal acoustic canal malformation in children with unilateral SNHL under one year of age was significantly higher than
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children, with unilateral SNHL, over 1–15 years of age [13]. In the current study, subjects with unilateral CH are accompanied by normal cochlea and also other types of IEM. As mentioned earlier developmental arrest is crucial in occurrence of IEM, besides this the vestibulocochlear artery supplies are also important, especially in unilateral and coexistent pathologies [9]. In this study, incomplete partition type-I (IP-I) was the most common accompanying malformation for CH. Others were common cavity, Michel deformity and cochlear aplasia. Sennaroglu explained this co-occurrence of CH and IP-I with vascular supply [9]. In the literature, there are some studies related to audiologic results of IEM and most of the studies focus on such patient’s performance after CI or ABI. Coticchia evaluated the radiological findings of 69 subjects with SNHL and found 17 subjects with IEM. 14 subjects participated in the study, 2 had profound HL, 4 had severe HL, 7 moderate HL and one subject had mild HL [14]. However, the type of IEM was not stated. Bamiou re-evaluated radiological results and audiological testing was done again on 35 subjects with unilateral HL. They reported there were 12 subjects with IEM and internal acoustic meatus anomaly [15]. In the same way as the previous study, they also did not mention the type of IEM. Different from these studies, the current study focuses especially on the CH subgroup of IEM and tries to describe audiological results according to four different types of CH. It was found that HL shows variation according to types of CH. In the CH-I, CH-II and CH-III groups, HL varies from moderate to profound and also some cases had no response to sound on subjective testing. However, the CH-IV group had mild HL to profound HL and also all cases in this group had responses to sound at subjective testing. In embryological development, any arrest in 6th and 8th week, could result in CH-I, CH-II and CH-II, except CH-IV. Since basal turn is present in CH-IV, insult should be in 10th and 20th week. It could be inferred that latest insult produces the better hearing sensitivity. In this aspect the CH-IV group is significantly different from the other three groups of CH. When we look at types of HL in CH, 79.1% was SNHL, 18.52% was mixed type HL and 2.47% was CHL. The rate of SNHL is similar on across the CH-I, CH-II and CH-III groups and there was no pure CHL but some cases had mixed HL. However, only the CH-IV group includes pure conductive HL besides SN and mixed type HL. The CH-IV group also differs significantly from other three groups. Mixed type HL is more concentrated in the CH-III group. In this study, there were 4 cases with stapedectomy, 2 of them had CH-IV and the other two CH-III. At this point it is important to check radiological results in terms of middle ear malformations in the presence of IEM. Sennaroglu reported some differences in histopathology of IEM. There were 8 specimens with stapes fixation and 6 of them had CH (2 CH-I, 3 CH-II and one CH-III). There were also 6 specimens with oval window aplasia and 5 of them had CH (1 CH-I, 1 CH-II and 3 CH-III). The stapes is a part of the otic capsule and if there is an arrest of otic capsule development before the formation of the footplate, it is natural that the stapes will become fixed to the oval window [9]. As a result of this stapes fixation, conductive or mixed type HL is expected. In the current study, there were subjects with CHL that had
Please cite this article in press as: Cinar BC, et al. Audiologic and radiologic findings in cochlear hypoplasia. Auris Nasus Larynx (2017), http:// dx.doi.org/10.1016/j.anl.2016.12.002
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stapedectomy. After stapedectomy, their thresholds improved and they were able to make better use of hearing aids. In the current study, all subjects’ radiological results were reviewed to check for CH type, CA and CN status. It has been reported that when there is IEM, it is possible to have cochlear aperture stenosis [2]. In this study, 51.79% of cases with CH had CA stenosis, 41.07% of cases had normal CA and 7.14% had CA aplasia. Aplasia of CA was present in the CH-I, CH-II and CH-III groups. However, there was no CA aplasia and mostly normal CA in the CH-IV group. CA stenosis is more concentrated in the CH-I and CH-II groups. Similar to the CHIV group, CH-III group also mostly has normal CA. In the same way with CA, CN also differs according to CH type. It was reported that CN hypoplasia and aplasia could accompany CH [3,16,17]. However, in the current study, the rate of normal CN was higher than in CN hypoplasia or aplasia in CH. In the CHIII group, the normal CN rate was highest but in CH-I, the CN aplasia rate was highest. In CH-I, CH-II and CH-III groups, there was CN aplasia but in the CH-IV group there were no case with CN aplasia. It is known that the status of the CN directly affects hearing and as a result aplasia of the CN can cause profound HL, but hypoplasia of the CN could be related to residual hearing [17]. In this study, hearing loss variation in the CH-IV group was mild to profound and this could be related to the status of the CN since there was no aplasia of CN in this group. In this study, hearing device types showed variability across the CH groups. Hearing aids, CI and ABI were used. Also, there was a group of cases not using any hearing device due to presence of normal hearing on the contralateral side; some others did not use a device due to limited or no benefit from hearing aids. In Turkey, CI or ABI applications are single sided due to non-reimbursement of bilateral implants. CI or ABI users mostly do not use a HA on the contralateral side due to insufficient benefit. In the study group, 28 cases use CI and 20 cases use ABI. While choosing a device IEM, CA, CN and residual hearing should be taken into consideration. Especially, in cases with CN hypoplasia it is difficult to decide between CI and ABI [2,18–22]. In the presence of hypoplastic CN, bilateral CI or ABI after removal of the CI electrode was used as an option for amplification [23,24]. In our study group, 5 cases use bimodal stimulation, CI on one side and ABI on the contralateral side. However, details of bimodal stimulation were not within the scope of this study. Also in our study, there is one case with mild HL and five cases with moderate to moderately severe HL in the presence of CN hypoplasia. Similar to our findings, Taiji reported 6 children with mild and moderate SNHL with CN hypoplasia [25] and some cases with normal CN had no response to sound in subjective testing. It could be inferred from this finding that for residual hearing just having a normal CN is not enough; hearing is the result of the total effect of cochlea, cochlear aperture and cochlear nerve. 5. Conclusion This study demonstrates that CH shows variability in terms of degree and type of HL and also CA and CN status. Other IEM types, especially IP-I, may accompany CH. The most common
type of cochlear hypoplasia in this study is CH-III. In general the CH-IV subgroup was statistically, significantly different from the other three CH groups. In the CH-IV group, there was mild HL, and all subjects with CH-IV had responses to sound. Pure conductive HL was present in only this CH-IV group. Also there was no case of CA or CN aplasia in CH-IV group and as a result there was no ABI user. It seems that even within the same subgroup of CH, HL degree and type have great variability. While evaluating radiological findings, both IEM and middle ear malformation should be taken into consideration. In our study, when there was conductive or mixed type of HL in the presence of CH, just for these cases CT results were reevaluated to check for middle ear malformation. However, the subjects with SNHL also should be re-evaluated for presence of middle ear malformations. This could be accepted as a limitation for this study. Conflict of interest There is no conflict of interest. Acknowledgements For this study, no outside found or grants were received. This study is based on first author’s doctoral dissertation. References [1] Sennaroglu L. Cochlear implantation in inner ear malformations – a review article. Cochlear Implants Int 2010;11:4–41. [2] Sennaroglu L, Sennaroglu G, Atay G. Auditory brainstem implantation in children. Curr Otorhinolaryngol Rep 2013;1:80–91. [3] Sennaroglu L, Ozkan HB, Aslan F. Impact of cochleovestibular malformations in treating children with hearing loss. Audiol Neurotol 2013;18(Suppl. 1):3–31. [4] Sennaroglu L, Saatci I. A new classification for cochleovestibular malformations. Laryngoscope 2002;112:2230–41. [5] Cho SW, Kang SI, Park SJ. Clinical characteristics of patients with narrow bony cochlear nerve canal: is the bilateral case just a duplicate of the unilateral case? Laryngoscope 2013;123:1996–2000. [6] Stjernholm C, Muren C. Dimensions of the cochlear nerve canal: a radioanatomic investigation. Acta Otolaryngol 2002;122:43–8. [7] Joshi VM, Navlekar SK, Kishore GR, Reddy KJ, Kumar ECV. CT and MR imaging of the inner ear and brain in children with congenital sensorineural hearing loss. RadioGraphics 2012;32:683–98. [8] Mann ZF, Kelley MW. Development of the inner ear. In: Moody SA, editor. Principles of developmental genetics. 2nd ed., USA: Elsevier Science & Technology Books; 2014. p. 377–91. [9] Sennaroglu L. Histopathology of inner ear malformations: do we have enough evidence to explain pathophysiology? Cochlear Implants Int 2016. [10] Gulya AJ. In: Gulya AJ, editor. Gulya and Schuknecht’s anatomy of the temporal bone with surgical implications. 3rd ed., New York, USA: Taylor & Francis Group; 2007. 376 pp. [11] Erixon E, Ho¨gstorp H, Wadin K, Rask-Andersen H. Variational anatomy of the human cochlea: implications for cochlear implantation. Otol Neurotol 2009;14–22. [12] Bartel-Friedrich S, Wulke C. Classification and diagnosis of ear malformations. GMS Curr Top Otorhinolaryngol Head Neck Surg 2007;6. [13] Masuda S, Usui S, Matsunaga T. High prevalence of inner-ear and/or internal auditory canal malformations in children with unilateral sensorineural hearing loss. Int J Pediatr Otorhinolaryngol 2013;77: 228–32.
Please cite this article in press as: Cinar BC, et al. Audiologic and radiologic findings in cochlear hypoplasia. Auris Nasus Larynx (2017), http:// dx.doi.org/10.1016/j.anl.2016.12.002
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ANL-2220; No. of Pages 9 B.C. Cinar et al. / Auris Nasus Larynx xxx (2016) xxx–xxx [14] Coticchia JM, Gokhale A, Waltonen J, Sumer B. Characteristics of sensorineural hearing loss in children with inner ear anomalies. Otolaryngol Head Neck Surg 2006;27:33–8. [15] Bamiou DE, Savy L, O’ Mahoney C, Phelps P, Srimanna T. Unilateral sensorineural hearing loss and its aetiology in childhood: the contribution of computerised tomography in aetiological diagnosis and management. Int J Pediatr Otorhinolaryngol 1999;51:91–9. [16] Puram S, Tward AD, Jung DH, Dilger AE, Herrmann BS, Duhaime AC, et al. Auditory brainstem implantation in a 16-month-old boy with cochlear hypoplasia. Otol Neurotol 2014;36:618–24. [17] Li Y, Yang J, Liu J, Wu H. Restudy of malformations of the internal auditory meatus, cochlear nerve canal and cochlear nerve. Eur Arch Otorhinolaryngol 2014. [18] Sennaroglu L, Colleti V, Manrique M, Laszig R, Offeciers E, Saeed S, et al. Auditory brainstem implantation in children and non-neurofibromatosis type 2 patients: a consensus statement. Otol Neurotol 2011;32:187–91. [19] Govaerts PJ, Casselman J, Daemers K, Beukelaer CD, Yperman M, Ceulaer GD. Cochlear implants in aplasia and hypoplasia of the cochleovestibular nerve. Otol Neurotol 2003;24:887–91.
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[20] Young N, Kim FM, Ryan ME, Tournis E, Yaras S. Pediatric cochlear implantation of children with eighth nerve deficiency. Int J Pediatr Otorhinolaryngol 2012;76:1442–8. [21] Bradley J, Bell M, Beale T, Graham JM. Variable long term outcomes from cochlear implantation in children with hypoplastic auditory nerves. Cochlear Implants Int 2008;9:34–60. [22] Colletti L, Colletti G, Mandala M, Colletti V. The therapeutic dilemma of cochlear nerve deficiency: cochlear or brainstem implantation? Otolaryngol Head Neck Surg 2014;151:308–14. [23] Oker N, Loundon N, Marlin S, Rouillon I, Leboulanger N, Garabe´dian EN. Bilateral implantation in children with cochleovestibular nerve hypoplasia. Int J Pediatr Otorhinolaryngol 2009;73. [24] Colletti L, Wilkinson EP, Colletti V. Auditory brainstem implantation after unsuccessful cochlear implantation of children with clinical diagnosis of cochlear nerve deficiency. Ann Otol Rhinol Laryngol 2013;122:605–12. [25] Taiji H, Morimoto N, Matsunaga T. Unilateral cochlear nerve hypoplasia in children with mild to moderate hearing loss. Acta OtoLaryngol 2012;132:1160–7.
Please cite this article in press as: Cinar BC, et al. Audiologic and radiologic findings in cochlear hypoplasia. Auris Nasus Larynx (2017), http:// dx.doi.org/10.1016/j.anl.2016.12.002