The incidence of sensorineural hearing loss (SNHL) increased gradually in the past decades. High-resolution computed tomography (HRCT) and magnetic resonance (MR) imaging, as an important part of preimplantation evaluation for children with SNHL, could provide the detailed information about the inner ear, the vestibulocochlear nerve, and the brain, so as to select suitable candidate for cochlear implantation (CI). Brain abnormalities were not rare in the brain MR imaging of SNHL children; however, its influence on the effect of CI has not been clarified. After retrospectively analyzing the CT and MR imaging of 157 children with SNHL that accepted preoperative evaluation from June 2011 to February 2013 in our hospital and following them during a period of
The incidence of sensorineural hearing loss (SNHL) was about 1/1000 in the newborns and about 9/1000 in the school age children, and it was still increasing gradually in the past decades [
Imaging examination played an important role in the preimplantation evaluation of pediatric SNHL [
Till now, several studies had clarified the incidence of the inner ear malformation or vestibulocochlear nerve deficiency and their influence on CI [
Therefore, based on a large cohort of 157 patients who accepted preimplantation evaluation for SNHL in our hospital, we try to study the incidence of brain abnormalities and to clarify the influence of brain abnormalities on the hearing improvement after CI, further to clarify whether the brain abnormalities should be viewed as the contraindication of CI.
This study was approved by our institutional review board. From June 2011 to February 2013, 157 children with SNHL accepted HRCT and MR scan as a part of preoperative evaluation. The 157 patients consisted of 89 boys and 68 girls with a mean age of 4.3 years (range: 1–15 years). Audiological evaluation indicated that there were 137 children with bilateral SNHL and 20 children with unilateral SNHL. Among all the 157 children with SNHL, 26 brain abnormalities were found on the brain MR imaging of 23 patients, and the incidence was 14.6% (23/157).
All patients underwent both HRCT and MR scans of the temporal bone. The HRCT scans were performed using a 16-slice spiral CT scanner (SOMATOM Emotion, Siemens, Germany). Parameters for the CT scanning are kV: 120, mAs: 28, and slice thickness: 1 mm. Volumetric acquisitions were reconstructed with 0.75 mm slice thickness throughout the temporal bone contiguously. The transverse imaging plane was parallel to the supraorbital-meatal line. This allowed creating multiplanar reconstructions in any plane. Bone window settings were designed as window level of +700 Hounsfield unit (HU) and window width of +4000 HU.
MR imaging was obtained on a 3.0 Tesla MR scanner (Siemens, Germany) with the matched eight-channel phased array coils. The MR protocol included axial T2-weighted imaging and axial T1-weighted imaging, as well as axial three-dimension sampling perfection with application optimized contrasts using different flip angle evolutions (3D-SPACE) imaging of temporal bones. Parameters for the T1 sequence are TR/TE, 250/2.5 ms; slice thickness, 5 mm. Parameters for the T2 sequence are TR/TE, 5000/100 ms; slice thickness, 5 mm. Parameters for the 3D-SPACE sequence are TR/TE, 1000/131 ms; flip angle, 120; averages, 2; field of view, 200 mm; matrix size,
CT and MR imaging were assessed on a clinical picture archiving and communication system (PACS) workstation by two radiologists (Wu FY, Xu XQ). Brain abnormality was defined as any abnormal signal or structural abnormality demonstrated on the brain MR imaging. If the volume of the white matter lesion was less than 10% of that of the whole white matter, the lesion was categorized as a “focal lesion.” Otherwise, the lesion was classified as a “diffuse lesion.”
Patients were followed up mainly through the manner of phone calls. Except that one patient with bilateral SNHL was lost during the follow-up, we successfully followed up the other 22 patients with SNHL within a period of
IT-MAIS consisted of a series of 10 questions. Questions 1 and 2 related the bonding of the child to the device, including the willingness of the child to wear it and his ability to recognize and identify device malfunction. Questions 3 to 6 related the alerting to sound of the child when not in a “listening set.” Questions 7 to 10 related to the ability of the child to derive meaning from the auditory phenomena (Table
Follow-up of 23 SNHL patients with brain abnormalities after cochlear implantation.
Abnormal brain MRI findings | Concurrent abnormalities | Y/S | U/B | CI | IT-MAIS | FU (Mon) | Focal/diffuse | |
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Before | After | |||||||
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Bilateral frontal and temporal subcortical area |
— | 1/M | B | Yes | 0 | 10 | 15 | Diffuse |
Multiple WMC lesions | — | 1/M | U | No | — | — | 12 | — |
Right posterior horn of lateral ventricle | — | 4/M | B | Yes | 3 | 31 | 14 | Focal |
Bilateral posterior horn of lateral ventricle | Malformed semicircular canal | 2/F | B | Yes | 1 | 34 | 16 | Focal |
Bilateral periventricular area |
— | 1/M | U | No | — | — | 9 | — |
Bilateral frontal and parietal subcortical area | — | 1/M | B | Yes | 1 | 29 | 27 | Focal |
Bilateral posterior horn of lateral ventricle | Bilateral mastoiditis | 1/M | B | Yes | 2 | 27 | 18 | Focal |
Multiple WMC lesions | — | 1/F | B | Yes | 1 | 23 | 12 | Diffuse |
Multiple WMC lesions |
— | 15/F | B | Yes | 2 | 16 | 20 | Diffuse |
Multiple WMC lesions | Bilateral mastoiditis | 1/M | B | Yes | 2 | 24 | 8 | Diffuse |
Bilateral periventricular area | — | 1/M | B | Yes | 2 | 25 | 7 | Focal |
Bilateral frontal subcortical area |
Bilateral mastoiditis | 5/M | B | Yes | 1 | 24 | 11 | Diffuse |
Bilateral periventricular area | — | 3/M | U | No | — | — | 18 | — |
Right posterior horn of lateral ventricle | — | 4/F | B | Yes | 2 | 27 | 18 | Focal |
Bilateral posterior horn of lateral ventricle |
Cochlear hypoplasia |
3/F | B | No | — | — | 11 | — |
Bilateral periventricular area | — | 1/M | B | L |
— | — | — | — |
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Cisterna magna enlargement | — | 2/M | B | Yes | 1 | 28 | 15 | — |
Arachnoid cyst (left temporal area) | — | 1/M | B | Yes | 1 | 24 | 12 | — |
Arachnoid cyst (left temporal area) | — | 3/F | B | Yes | 2 | 29 | 9 | — |
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Intraparenchymal cystic lesions |
— | 1/M | B | Yes | 2 | 22 | 7 | — |
Intraparenchymal cystic lesions |
— | 3/F | B | Yes | 3 | 25 | 22 | — |
Intraparenchymal cystic lesions |
— | 3/M | B | Yes | 2 | 26 | 13 | — |
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Abnormal enlargement of subarachnoid space |
Enlarged vestibular aqueduct | 1/F | B | Yes | 0 | 17 | 16 | — |
Y, year old; S, sex; U, unilateral SNHL; B, bilateral SNHL; CI, cochlear implantation; FU, follow-up.
L
The numerical data were averaged and reported as means ± standard deviation (SD). Improvement of IT-MALS score in “diffuse lesion” group and “focal lesion” group before and after CI was compared with Wilcoxon analysis.
Among all the 157 patients with SNHL, 26 brain abnormalities were found on the MR imaging of 23 patients, and the incidence was 14.6% (23/157). The most common abnormality was pure white matter changes (
Among the 23 patients with brain abnormalities, concurrent abnormalities were found in 6 children, including bilateral mastoiditis (
Among the 16 patients with white matter changes, 15 patients were successfully followed up. Among the 15 patients, 13 patients or their mothers had a history of medical condition that could be associated with the brain abnormalities, including viral influenza (
Twenty-three patients with brain abnormalities included 20 patients with bilateral SNHL and 3 patients with unilateral SNHL. After excluding the 3 unilateral cases that did not accept CI, one bilateral SNHL patient who gave up CI due to the complicated inner ear malformation, and one bilateral SNHL patient who was lost during the follow-up, a total of 18 patients with bilateral SNHL accepted CI.
Among the 18 patients, the IT-MAIS score improved from
MR imaging of a representative patient with SNHL. (a, b) Axial T1 and T2 weighted imaging showed abnormal signal in the white matter in the bilateral periventricular area and enlargement of septum pellucidum. (c, d) Sagittal 3D-SPACE imaging showed the normal facial nerve, cochlear nerve, and vestibular nerves in the internal auditory canal. (e, f) Volume rendering imaging showed the normal structure of the inner ear. IT-MAIS score of this patient improved from 0 to 10 after CI.
Eleven patients with white matter changes included 5 patients with “diffuse lesion” and 6 patients with “focal lesion.” In the “diffuse lesions” group, except one patient who was 15 years old, the other 4 patients were 1, 1, 1, and 5 years old, respectively, with a mean age of
IT-MAIS score of children with SNHL before and after cochlear implantation.
Group | All SNHL children ( |
WMC group ( |
WMC group ( |
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IT-MAIS score | Before | After | Before | After | Diffuse ( |
Focal ( |
1.55 ± 0.86 | 24.50 ± 5.68 | 1.54 ± 0.82 | 24.55 ± 6.71 | 18.20 ± 5.85a | 27.00 ± 3.10b | |
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WMC indicates white mater change. The number in the parenthesis means the number of the patients in each group. a,bThe score means the improvement of IT-MAIS score in the two groups.
The incidence of brain abnormalities in our study was 14.6%, relatively lower than previous studies, which demonstrated that the incidence of brain abnormalities varied from 20% to 56% [
The white matter changes were the most common brain abnormality. In our study, the incidence of white matter changes was 69.6%, which was similar to previous studies [
The white matter changes were viewed as an important marker of abnormal neurodevelopment and might help to predict potential future problems (seizure and intellectual impairment) in certain patients [
Our study had several limitations. First, our study was a retrospectively clinical observational and descriptive study. We could just describe the different brain abnormalities existing in brain MR imaging of the patients with SNHL and correlated the imaging findings with the medical histories, so as to analyze the potential cause of the brain abnormalities. However, no exact pathological evidence could be achieved for supporting our research result. Secondly, the number of the SNHL patients with brain abnormalities and the period of follow-up time were limited. Further study with more patients and longer follow-up time was needed to confirm our results.
Brain abnormalities were common on the brain MR imaging of the patients with SNHL; therefore, the whole brain MR scan was necessary in the preimplantation evaluation. The white matter changes, which were the most common brain abnormalities, might be associated with the history of medical condition during the gestation and perinatal period. Brain abnormalities might not influence the short-term hearing improvement after CI. Further study with more patients and longer follow-up time was needed to confirm our results.
None of the authors has identified a potential conflict of interests.
Xiao-Quan Xu assessed images and wrote the paper, Fei-Yun Wu designed the paper and assessed images, Hao Hu followed up all the patients in the study, Guo-Yi Su helped with MR scan for all the patients, and Jie Shen helped with CT scan for all the patients.