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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 20  |  Issue : 1  |  Page : 142-147

Role of computed tomography and MRI in children with sensorineural hearing loss


1 Resident of Diagnostic Radiology, Faculty of Medicine, Al-Azhar University Hospital, Assiut, Egypt
2 Professor & Head Chair of Radiology Department, Faculty of Medicine, Al-Azhar University, Assiut, Egypt
3 Lecturer of Diagnostic Radiology, Faculty of Medicine, Al-Azhar University, Assiut, Egypt
4 Lecturer Of Audio-Vestibular Medicine, Faculty of Medicine, Al-Azhar University, Assiut, Egypt

Date of Submission02-Dec-2020
Date of Decision08-Dec-2020
Date of Acceptance23-Dec-2020
Date of Web Publication4-Mar-2022

Correspondence Address:
BSc Ahmad Mohamed Saeed Alkady
Resident of Diagnostic Radiology, Faculty of Medicine, Al-Azhar University Hospital, Al-Behira, Postal Code: 22726
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/azmj.azmj_191_20

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  Abstract 


Background and aim Given the tremendous developments in visualization science, there are many congenital and acquired internal ear anomalies that have no radiological signs. However, visualization is an important instrument for the assessment of congenital and acquired sensory neural hearing loss (SNHL) triggers. The aim is to assess the value of multidetector computed tomography (MDCT) and MRI in internal ear abnormality detection in children with SNHL.
Patients and methods This study included 100 children of 10 years or younger with SNHL. The cochlea, the vestibule, the three semicircular canals, the endolymphatic duct, and the internal acoustic canal. In addition, three-dimensional DRIVE MRI gives good demonstration of all four nerves within the internal acoustic canal.
Results A total of 46 malformations were detected in only 25 patients with 42 malformations that were detected in MDCT examination presenting 91% of all abnormalities, while in MRI examination, 44 malformations are detected presenting 96% of all abnormalities. MDCT showed accuracy, sensitivity, and specificity 96.7, 91.3, and 100%, respectively, while for MRI, it showed accuracy, sensitivity, and specificity 98.3, 95.7, and 100%, respectively.
Conclusion Imaging plays an important role in the workup of children with SNHL. Therefore, it is imperative to define the etiology of hearing loss. High-resolution CT and MRI modalities are the two principal radiological investigations to detect various pathologies in the inner ear. ‘Dual-modality imaging’ using both MRI and CT, made sense for many patients because the dual-scan approaches detect abnormalities related to hearing loss that would not otherwise be found using either modality alone.

Keywords: computed tomography, extended vestibular aqueduct, hearing loss, multidetector computed tomography, Mondini, MRI, sensory neural hearing loss


How to cite this article:
Alkady AS, Al-Wahed El-Gebaly SA, Mansour TM, Elmoursy Kasem MM. Role of computed tomography and MRI in children with sensorineural hearing loss. Al-Azhar Assiut Med J 2022;20:142-7

How to cite this URL:
Alkady AS, Al-Wahed El-Gebaly SA, Mansour TM, Elmoursy Kasem MM. Role of computed tomography and MRI in children with sensorineural hearing loss. Al-Azhar Assiut Med J [serial online] 2022 [cited 2022 Jun 29];20:142-7. Available from: http://www.azmj.eg.net/text.asp?2022/20/1/142/339070




  Introduction Top


Hearing impairment is one of the common birth defects seen in —three to four newborns out of 1000 [1].

A number of diseases may cause hearing impairment in children [2]. With the advent of the universal screening, hearing loss can be diagnosed earlier in life [3].

The cochlear implant is a high technological tool that is surgically implanted into the cochlea of patients having severe-to-profound bilateral sensorineural loss of hearing and who have not gained from traditional auditory-enhancement aids. The goal is to activate auditory-nerve fibers electrically, such that cochlear activity is partly lost [4].

As the incidence of cochlear implants has grown, imaging demand has also grown as operating cochlear-implant recipient, such that the imaging finding that contraindicates implantation must be recognizable to the radiologist [5].

Preoperative evaluations of applicants for cochlear implantation include health, speech language, academic, and social requirements. At this point, the MRI of the cochlear area is important to evaluate the etiology of hearing loss, to distinguish outcomes that could contraindicate operation, to help choose the ear to be inserted, to accurately assess the anatomy to be operated, and to anticipate potential complications [4].

Imaging thus plays a significant role in the selection of cochlear-implant recipients. Therefore, the etiology of hearing loss must be preoperatively established [5].

The two main radiological investigations include high-resolution CT and MRI [6].

Three-dimensional (3D)-driven equilibrium (DRIVE) is a gradient-echo MRI sequence used to study a range of various pathologies if the desired anatomical information is not provided by routine MRI sequences. The improved flexibility of the 3D DRIVE series is a product of the focus on T2 between the cerebrospinal fluid and the pathologic structure [7].

3D DRIVE is commonly used to determine cerebellopontine angle harm, internal ear structures, and internal auditory canal. This can clearly demonstrate the fine structure of the cranial nerves VII and VIII and the membranous labyrinth of the inner ear [7].

The aim of this research was to determine the effectiveness and utility of dual multidetector computed tomography (MDCT) and MRI studies in children with special interest to DRIVE and to estimate the proportion of radiological anomalies identified in both approaches.


  Patients and methods Top


This study included 100 children with sensory neural hearing loss (SNHL) under the age of 10 years referred to the Radiology Department of Al-Azhar Assiut University Hospital from Audio-Vestibular Medicine Unit, in the period from January 2019 to June 2020, for radiological assessment of petrous bone. Ethics approval and consent to participate: This study was done after approval from the AL-AZHAR university hospital-faculty of medicine Assiut and after patient agree verbal consent (As the patients not exposed to any type of surgical or interventional maneuver).

Inclusion criteria were children with SNHL referred from Audio-Vestibular Medicine Unit with severe-to-profound degrees of hearing loss who are included. Both sexes are included in this study for all children under 10-year-old.

Exclusion criteria were general contraindication to MRI and children with conductive hearing loss or mixed hearing loss.

Informed consent will be taken from the child’s parents and all cases were subjected to full history taking (age, history, degree, and duration of hearing loss) and audiological evaluation that includes either play audiometry or conventional audiometry according to the reliability of the child and auditory brainstem response for younger babies.

Radiological examination included CT petrous bone [Simens Emotion 16 Multislices, German (European)] and MRI petrous bone (Philips Achieva 1.5 T, USA).

CT scanning was done after a detailed explanation of the procedure to the parents of the children. CT scan was performed using MDCT scanning in the axial plane with a 16-channel MDCT scanner (CT Simens Emotion 16 Multislices).

The MRI examinations of all children were performed on an Achieva 1.5 T (Philips healthcare system). A three-plane localizer must be taken in the beginning to localize and plan the sequences. TIWI low-resolution scans (axial T1-weighted images, axial T2-weighted images, coronal T1-weighted images, coronal T2-weighted images, and 3D).

The following structures were assessed on both 3D MRI and CT exams and designed as pathological or normal: the cochlea, the vestibular system, the three semicircular canals, the endolymphatic duct and sac, and the internal auditory canal and the appearance of the osseous labyrinth on CT and the membranous labyrinth on MRI.

In addition, on 3D DRIVE MRI, careful attention was paid to the sensitivity of all four nerves in the internal acoustic canal as well as to the unusual signal intensities inside the cochlear labyrinth.

All data were statistically described in terms of mean±SD, and range, or frequencies and percentage when appropriate. Accuracy was represented using the terms sensitivity, specificity, and overall accuracy. All statistical calculations were done using SPSS 20.0 software (IBM Information, technology and services, Armonk, New York, NY, USA).


  Results Top


This study included 100 patients, 58 (58%) males and 42 (42%) females, with bilateral severe-to-profound SNHL. They were referred from Audio-Vestibular Medicine Unit to the Radiology Department at Al-Azhar Assiut University Hospital, for radiological assessment of the inner ear and petrous bone. Their ages ranged between 1 and 10 years.

In our study, out of 100 pediatric patients, no significant radiological abnormality was detected in 75 (75%) patients, however, 25 (25%) patients had various congenital anomalies of the inner ear and eighth cranial nerve. A total of 46 malformations were detected in both modalities (MDCT and MRI) in 25 patients. All the 25 children have bilaterally abnormal inner ear, except for two children who have unilateral abnormal ear.

The results with MDCT examination of the patient are concluded in [Table 1], while the results of MRI examinations of the patients are concluded in [Table 2].
Table 1 Multidetector computed tomography findings in 25 patients with internal ear anomalies

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Table 2 MRI finings in 25 patients with internal ear anomalies

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Correlation between MDCT findings and MRI findings: this study showed that high-resolution CT scan and MRI revealed similar morphological findings of abnormal inner ears, except for vestibulocochlear nerves, which were more appreciated on MRI scan ([Table 3]).
Table 3 Distribution of multidetector computed tomography and MRI findings among 25 patients

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A total of 46 malformations were detected in 25 patients with abnormal radiological findings, 42 findings were detected in MDCT examination presenting 91% of all abnormalities, while in MRI examination, 44 findings are detected presenting 96% of all abnormalities.

MRI evaluation of the patients showed specific findings that were more demonstrated than MDCT regarding the high soft-tissue evaluation capabilities of MRI. These findings include vestibulocochlear nerve aplasia in four patients presenting 16%.

The correlation between MDCT and MRI results and demonstration of various inner-ear anomalies in 100 patients presenting with SNHL showed accuracy, sensitivity, and specificity 96.7, 91.3, and 100%, respectively, for MDCT ([Table 4]), while for MRI, it showed accuracy, sensitivity, and specificity 98.3, 95.7, and 100%, respectively ([Table 5]).
Table 4 Accuracy, sensitivity, and specificity of the multidetector computed tomography

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Table 5 Accuracy, sensitivity, and specificity of the MRI

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  Discussion Top


CT has become the modality of choice of screening for cochlear-implant recipients to test the temporal bone. Systematic research on the efficacy of surgery for congenital or inherited internal ear conditions, retrocochlear and anatomical forms of the middle ear, and the mastoid [8].

In our high-resolution analysis, MDCT revealed a malformation of the inner ear in 25 (25%) patients. The remainders of the inner ears are appearing normal ([Figure 1]). This was aligned with multiple incident studies, including Sun et al. [9], which reported that 30.69% of inner-ear malformation may be identified in his broad epidemiological review, which involved 2747 cases, in cases with SNHL.
Figure 1 Axial CT image showing normal inner-ear structures, normal apical cochlear turn and modiolus, and normal vestibule (green arrows) and VA (black arrow). CT, computed tomography; VA, vestibular aqueduct.

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Bony inner-ear malformations are somewhat rare disorders, affecting around 20% in congenital sensorineural hearing-deficiency events. About 80% of the residual instances of congenital anomalies are membranous malformations in which the inner ear’s bony architecture is intact and functional. This is accepted with our analysis since we detect anomalies in 25% only, and in radiology, we detect the other 75% normal [10].

The most common internal-ear abnormality in 12 patients was an expanded vestibular aqueduct (48% of 25 reports of inner-ear anomalies). This agreement with Saliba et al. [11] found that the enhanced usage of high-resolution CT scans indicated that extended vestibular aqueduct was the most frequently detected inner-ear abnormality ([Figure 2]a and b) in unknown SNHL infants.
Figure 2 (a) Axial MDCT image shows bilateral enlarged vestibular ducts. (b) Axial three-dimensional DRIVE MRI shows large endolymphatic sac anomalies bilaterally (blue arrows). MDCT. multidetector computed tomography.

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We also observed that in four patients with 16%, Taha et al. [8], incomplete type-II partition was detected ([Figure 3]), and reported that IP-II deformity is the most prevalent kind of cochlear malformation in which over 50% of all cochlear malformations occurs.
Figure 3 Three-dimensional MRI showing deformed apical turn of the cochlea at both sides (bilateral IP-II).

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A complete labyrinthine aplasia (Michel aplasia) is seen only in one patient representing 4% of 25 cases, this is typically corresponding to Joshi et al. [12], who stated: Michel aplasia is the most intense form of inner-ear deformity. This malformation is very rare, only one (4%) out of 25 patients had this inner-ear malformation. However, in most of the studies, its incidence was ∼1%.

In this study, we found seven (28%) patients with bilateral semicircular canal dysplasia and aplasia, which is a less incidence than that described in Dagkiran et al. [13]. The research finds 10 (7.3%) ears with reverse semicircular channels, 10 (7.4%) ears with lateral semicircular channels, eight (5.9%) ears with superior semicircular channels aplasia and hypoplasia, and eight ears with lateral semicircular canals’ vestibular dysplasia that can be clarified by the limited sample size of our analysis and through considering the independent semicircular channel deformity and not the group that associated with Mondini.

New progress in MRI technology has added value to this method in the assessment of recipients for cochlear implants. Cochlear implant needs the existence of a cochlea (normal or malformed) and of a cochlear nerve as the main principles [6].

3D DRIVE series reduces flow-void artifacts and increases fluid brightness. It was also precise when determining internal cochlear partitions, mild cochlear hypoplasia, and related cochlear-nerve defects. Tiny fibrotic bands may also be established that accompany labyrinthitis and attenuate the cochlear lumen. Its reconstruction into sagittal-type and coronal-type views helps the cochlear-nerve abnormalities that are discussed with Taha et al. [8], to be properly defined.

In our study, we found that 3D MRI was very efficient in demonstration of cochlear nerve ([Figure 4]) along its whole course from its origin in the brainstem and along its whole length in the cerebellopontine angle. It can easily demonstrate any hypoplasia, aplasia, or atrophy. It can also assess cochlear lumen patency and minor hypoplasia. Our results agreed with Al-Rawy et al. [14] who stated that 3D DRIVE was the mainstay for diagnosis of cochlear-nerve dysplasia, aplasia, or atrophy, which is mandatory for making decisions for cochlear implant in children with SNHL.
Figure 4 Three-dimensional MRI sagittal view shows normal vestibule–cochlear nerve (red arrow).

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The correlation between MDCT and MRI (as a gold standard) decisions in patients with SNHL showed higher sensitivity for MRI than CT in anomaly detection, where the MDCT shows sensitivity of 91.3% ([Table 4]), while the MRI is 95.7% ([Table 5]). This was explained by the ability of MRI to detect the vestibulocochlear nerve aplasia and dysplasia, which is not seen in CT even in the sagittal oblique images. This is concordant with Al-Rawy et al. [14].


  Conclusion Top


We conclude that MRI and CT have become essential parts of the diagnostic workup in children with severe-to-profound hearing loss.

Both imaging modalities are complementary. The strength of CT lies in the better delineation of the osseous otic capsule. While the MRI is beneficial in the evaluation of the vestibule–cochlear (VIII CN) nerve, 3D DRIVE MRI is the prime requirement for cochlear implant. It can easily demonstrate the presence of cochlear-nerve hypoplasia, dysplasia, or atrophy. Also, it can evaluate the presence of cochlea either normal or malformed. These are the most immanent findings upon which the decision will be taken for cochlear implantation.

We recommend a short protocol for assessment of children with severe-to-profound SNHL, including:
  1. MRI 3D DRIVE for evaluation of cochlear nerve (normal or abnormal) and cochlea (present or not and patent or not).
  2. High-resolution MDCT of petrous bone for evaluation of bony labyrinth and its variants that may influence or modify the surgery plan if cochlear implant is needed.


Acknowledgements

The authors are grateful to all the family members and fiancée for their support and patience throughout the preparation of the thesis. Without their encouragement, this work would never have been completed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

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



 

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