Magnetic resonance imaging versus computed tomography in pre-operative evaluation of cochlear implant candidates with congenital hearing loss

Recent reports indicate that the cochlear nerve may be absent in some cases of congenital sensorineural hearing loss. The aim of this prospective study was to determine the incidence of cochlear nerve anomaly in cochlear implant candidates with congenital hearing loss using magnetic resonance imaging (MRI). Twenty-seven patients with congenital profound bilateral sensorineural hearing loss who were being evaluated for the cochlear implant procedure were studied. These patients had high-resolution computerized tomography (CT), through the petrous bone in axial sections. MRI examinations consisted of T1 and turbo spin echo (TSE) T2-weighted 3 mm axial images, and additional 3D Fourier Transform T2-weighted TSE sequences obtained on three different planes (axial, perpendicular and parallel to the internal auditory canal (IAC) i.e. oblique sagittal and coronal, respectively) for the purpose of cochlear nerve demonstration. Results showed that all of the 14 patients with normal CT of the temporal bone, had four distinct nerves in the distal part of the IAC on TSE-MRI. Thirteen patients demonstrated various bony malformations of the cochleovestibular system on CT. MRI revealed the absence of the cochleovestibular nerve in four patients where the IAC was very narrow or completely absent on CT. One patient with severe Mondini malformation who had an enlarged IAC demonstrated an isolated absent cochlear nerve.     

Functional magnetic resonance imaging may avoid misdiagnosis of cochleovestibular nerve aplasia in congenital deafness

OBJECTIVE: To investigate a narrow internal auditory canal (IAC) syndrome using functional magnetic resonance imaging (fMRI) of the auditory cortex. STUDY DESIGN: The study design was a case report. The follow-up period lasted 18 months. SETTING: The study was carried out in the audiology clinic of an ear, nose, and throat department and in the department of pediatric neuroradiology at a university hospital. MAIN OUTCOME MEASURES: Age-appropriate observational audiometry, objective audiovestibular tests, computed tomography (CT), magnetic resonance imaging (MRI), and (fMRI) of the auditory cortex were performed to analyze in detail the profound deafness of a young child. RESULTS: Audiovestibular examination demonstrated both measurable hearing and normal vestibulo-ocular reflex, and CT showed narrow IACs combined with normal labyrinths. Axial MR images completed by sagittal sections perpendicular to the IAC delineated a single nerve that was initially supposed to be the facial nerve. No cochleovestibular nerve was identified. However, fMRI performed with the patient under general anesthesia demonstrated activation of the primary auditory cortex during 1-kHz monaural stimulation on the left side. CONCLUSIONS: The absence of cochleovestibular nerve on MR studies cannot exclude connections between the inner ear and the central auditory pathways. This might be caused by a lack of spatial resolution of anatomical MR studies. The single nerve delineated within the IAC might also carry both facial and cochleovestibular fibers. Functional MRI can assess the cortical response to acoustic stimuli when aplasia of the cochleovestibular nerve is suspected. This case study illustrates a novel and atypical presentation of cochlear nerve dysplasia.     

Facial nerve paralysis and meningioma of the internal auditory canal

Pathological lesions confined to the internal auditory canal (IAC) commonly present with cochleovestibular symptoms; sensorineural hearing loss, tinnitus and balance disturbance. The commonest lesion of the IAC is vestibular schwannoma. Other lesions include meningioma, facial neuroma, cavernous haemangioma, lipoma and arachnoid cyst. Presentation with facial palsy and an intracanalicular lesion is suggestive of pathology other than acoustic neuroma. Magnetic resonance imaging (MRI) cannot reliably distinguish intracanalicular vestibular schwannomas from meningiomas. Particular care is required for surgery of these lesions: the facial nerve typically does not lie in a protected anterior position within the IAC.     

Cellular Schwannoma in the Oral Mucosa

Conclusion. Preoperative CT and MRI assessment of children with severe or profound sensorineural hearing loss (SNHL) is critical for determining implant candidacy. Objectives. There are a significant number of children who do not show any auditory development with a cochlear implant (CI), possibly due to cochlear nerve (CN) aplasia/hypoplasia. Regardless of the suspected etiology, if a CI is not providing auditory development the clinician should carefully evaluate the possibility of a CN malformation and re-evaluate the child with detailed neuroimaging studies. If the imaging evaluation shows severe cochlear malformation or CN aplasia there is some developmental urgency to consider auditory brainstem implant (ABI) surgery. Subjects and methods. Twenty-eight children affected by congenital SNHL were examined by CT and MRI. Evaluation of the cerebellopontine angle (CPA), internal auditory canal (IAC), cranial nerves, and membranous labyrinth was performed. Six children had been previously fitted elsewhere with a CI with no sound detection. Results. Suspected congenital anomalies were confirmed by CT and MRI in all 28 children: 16 with associated labyrinthine malformations; 1 with outer, middle, and inner ear malformations; and 2 with associated monolateral facial nerve aplasia.     

先天性内耳道狭窄的多层螺旋CT和MRI表现

目的 总结先天性内耳道狭窄的多层螺旋CT(multiple slices CT,MSCT)和MRI影像学特点,提高对该病的认识.方法 回顾性分析13例(15耳)先天性内耳道狭窄患者MSCT和MRI检查的影像资料.结果 先天性内耳道狭窄单侧11例,双侧2例.MSCT显示内耳道管腔不同程度狭窄.孤立性内耳道狭窄3耳,合并其他畸形12耳,其中10耳仅合并内耳畸形,1耳同时合并内、中、外耳畸形,另1耳同时合并内、中、外耳畸形及额骨发育畸形.MRI检查15耳均显示前庭蜗神经发育细小;其中7耳蜗神经未显示,7耳蜗神经发育细小,1耳蜗神经显示不清;其中2耳面神经发育细小.容积再现(volume rendering,VR)图像可立体显示内耳道狭窄程度及伴发的内耳畸形.结论 MSCT 可显示内耳道狭窄的程度及伴发畸形,MRI则可显示其神经发育情况.

Abstract：

Objective To investigate multiple slice computed tomography ( MSCT) and magnetic resonance imaging( MRI) features of congenital stenosis of the internal auditory canal (CSIAC) and improve the ability for diagnosis.Method Thirteen cases with fifteen ears were studied.In all cases a MSCT and MRI was performed.Results Eleven cases were unilateral,and 2 cases were bilateral.MSCT could show the narrowness of IAC.Three cases were isolated,but the others were combined with inner ear malformations.One ear had inner,middle and outer ear malformations.One ear had inner,middle,and outer ear malformations with a frontal bone malformation.MRI demonstrated that all of the vestibulocochlear nerves were hypoplastic.The cochlear nerve in seven ears was not present,in seven ears the nerve was thinner,and in the last case it was poorly visualized.The facial nerve in two ears was hypoplastic.Volume rendering( VR) could present the degree of the narrowed internal auditory canals,combined with other inner ear anomalies.Conclusion MSCT will show the degree of the narrow internal auditory canals and combined anomalies,while the MRI can further demonstrate the nerves' development.     

Major and minor temporal bone abnormalities in children with and without congenital sensorineural hearing loss

OBJECTIVE: To determine the extent of correlation between sensorineural hearing loss (SNHL) and abnormal temporal bone anatomy in children. DESIGN: Axial and coronal high-resolution computed tomographic scans of the temporal bones of 247 children (494 ears) aged 2 months to 15 years with and without SNHL were blindly reviewed. The presence or absence of mild or severe cochlear dysplasias, vestibular dysplasias, and an enlarged vestibular aqueduct (VA) were recorded. The width of the VA was measured. The height, width, and length of the internal auditory canal (IAC) were measured, and abnormalities were described as narrow, widened, or bulbous. Clinical information was then reviewed to determine the presence or absence of a congenital syndrome and/or SNHL, and historical factors that might be responsible for SNHL. MAIN OUTCOME MEASURE: The relationship between radiographic findings and SNHL. RESULTS: One hundred thirteen patients (185 ears) had SNHL. Significant abnormal temporal bone anatomy in children with vs without SNHL included major cochlear and vestibular dysplasias (17% vs 0%; P<.001), enlarged VA (>2 mm) (5% vs 0%; P<.001), and narrow IAC (< or =2 mm) (4% vs 1%; P=.03). The average IAC width (4.85 vs 5.02 mm), height (4.39 vs 4.62 mm), and length (11.22 vs 11.44 mm) were not statistically different between children with vs without SNHL. In children with vs without SNHL, neither a widened (0.5% vs 3.6%) nor a bulbous (9% vs 8%) IAC was seen more often in children with SNHL. In ears with SNHL, the presence of a congenital syndrome significantly increased the risk of cochlear and vestibular abnormalities of the temporal bone (45% vs 14%; P<.001), including IAC abnormalities (30% vs 2%;P<.001), which overall were more commonly seen in children with (20%) vs without (3%) a congenital syndrome regardless of the presence of SNHL. No children with an enlarged VA had a congenital syndrome. CONCLUSIONS: Well-established temporal bone abnormalities such as cochlear and vestibular abnormalities and a grossly enlarged vestibular aqueduct are significantly found in children with SNHL. A narrow IAC is found more often in children with vs without SNHL. No significant correlation is found between SNHL and radiographic findings of a widened or bulbous IAC. In children with a congenital syndrome, more IAC abnormalities were seen, regardless of the presence of SNHL. In children with SNHL, the presence of a congenital syndrome increases the likelihood of a cochlear or vestibular abnormality.     

Causes of unilateral sensorineural hearing loss screened by high-resolution fast spin echo magnetic resonance imaging: review of 1,070 consecutive cases

OBJECTIVE: Evaluation of the ability of screening high-resolution, nonenhanced, fast spin echo (FSE) T2-weighted magnetic resonance imaging (MRI) of the internal auditory canal (IAC) and cerebellopontine angle (CPA) to detect nonacoustic schwannoma causes of unilateral sensorineural hearing loss (SNHL). FSE-MRI is equally sensitive in detecting acoustic (vestibular) schwannoma as gadolinium-enhanced MRI, but sensitivity to other causes of hearing loss is unknown. STUDY DESIGN: Retrospective review of screening FSE-MRI studies. SETTING: Academic otology/neurotology and neuroradiology practices. PATIENTS: There were 1,070 patients with unilateral SNHL who underwent radiologic screening for retrocochlear pathology. RESULTS: Normal findings were found in 944 cases. Typical (acoustic) vestibular schwannoma were found in 56 patients. Seventy additional lesions were identified: 27 CPA lesions, 29 inner ear lesions, and 12 intraaxial lesions including 9 infarctions, 1 multiple sclerosis case, 1 mesial temporal lobe sclerosis, and 1 colloid cyst. CONCLUSIONS: High-resolution T2 FSE-MRI of the IAC and CPA is a highly sensitive screening tool for unilateral SNHL, which can detect a variety of lesions in addition to vestibular schwannomas. To our knowledge in 2 years of follow-up in these patients screened for IAC/CPA lesions, no other lesions causing SNHL have been found. High-resolution FSE screening technique, used in conjunction with appropriate clinical prescreening and referral, can provide an equally sensitive method of evaluating unilateral SNHL compared to gadolinium-enhanced T1 MRI while reducing costs and providing distinct advantages in evaluating nonacoustic schwannoma causes of SNHL.     

内听道斜矢状位磁共振成像在人工耳蜗置入术前评估中的初步应用

目的:探讨内听道(IAC)斜矢状位MRI在人工耳蜗置入术前评估中的应用价值。方法:应用斜矢状位三维快速自旋回波T2加权MRI技术对15例(30耳)拟行人工耳蜗置入术患者的IAC进行扫描。结果:所有患者顺利完成检查,IAC内神经结构显示清楚。13例蜗神经正常的患者行人工耳蜗置入术并已成功开机,2例双侧蜗神经异常者未行耳蜗置入。结论:IAC斜矢状位MRI能清晰显示IAC内蜗神经的形态、大小及IAC的大小,是人工耳蜗置入术前判断蜗神经发育状况的良好方法。     

Value of computed tomography in the evaluation of children with cochlear nerve deficiency.

OBJECTIVE: To assess the predictive value of high-resolution computed tomography (HRCT) in the evaluation of children with cochlear nerve deficiency (CND). STUDY DESIGN: Retrospective review of medical records. SETTING:: Tertiary referral center, hospital setting. PATIENTS: Nineteen children (31 ears) with CND. INTERVENTIONS: Magnetic resonance imaging (MRI), HRCT, and audiologic evaluation. MAIN OUTCOME MEASURES: Comparisons of the morphology of the internal auditory canal (IAC), the bony cochlear nerve canal (BCNC) as seen on HRCT, and audiologic data. RESULTS: Of 12 ears with MRI evidence of an absent cochlear nerve (CN) and a normal-size IAC, all had a patent BCNC as revealed by HRCT. Four of these ears failed auditory stimulation after cochlear implantation, confirming clinically significant CND. Of 15 ears with a narrow IAC and a single nerve visible on MRI, 2 (13.3%) had a normal-size BCNC, 4 (26.7%) were narrow, and 9 (60.0%) were absent. One ear with a narrow IAC, normal BCNC, and a single nerve as revealed by MRI has benefited from cochlear implantation. CONCLUSION: Using BCNC patency, as revealed by HRCT, as a means of identifying CND would miss all cases of absent CNs in the setting of a normal-size IAC. Thus, MRI should be the primary modality for imaging children with severe to profound sensorineural hearing loss. When MRI demonstrates a single nerve within a narrow IAC, the addition of HRCT can further identify more than half of these cases as involving absent CNs because of an absent BCNC. In a subset of patients, CN status remains indeterminate.     

Internal auditory canal morphology in children with cochlear nerve deficiency.

OBJECTIVE: To describe the internal auditory canal (IAC) and inner ear morphologic characteristics of children with cochlear nerve (CN) deficiency. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: Fourteen children with small or absent (deficient) CNs have been identified by means of high-resolution magnetic resonance imaging (MRI). INTERVENTIONS: MRI of the brain. Clinical evaluation. MAIN OUTCOME MEASURES: Review of medical records, audiological testing results, and imaging studies. Images were evaluated for the structure of the cochlear, vestibular and facial nerves, IACs and inner ears. Audiometric thresholds were evaluated in all subjects. METHODS: Fourteen children with small or absent (deficient) CNs have been identified by means of high-resolution MRI. A review of the medical records, audiologic testing results, and imaging studies was undertaken. The images were evaluated for the structure of the cochlear, vestibular and facial nerves, IACs, and inner ears. The audiometric thresholds were evaluated in all subjects. RESULTS: Among the 14 patients, 5 had known syndromes. MRI allowed an exact specification of the nervous structures within all ears with normal-size IACs. Precise characterization of the nerves in ears with small IACs was more difficult, requiring a consideration of both imaging findings and functional parameters. Five children had bilateral deficient CNs, whereas the remaining 9 subjects were affected unilaterally. Thus, 19 ears had CN deficiency (absent CN, 16; small CN, 3). Eleven ears had normal-size IACs and deficient CNs. Of the 9 ears with small IACs, 8 had deficient CNs (absent, 7; small, 1) on the basis of both MRI and functional assessments. Two ears with small IACs had clear morphologic and/or functional evidence for the presence of a CN: one had a small-size CN on MRI, whereas another had a single nerve in a small IAC with present facial and auditory functions. CONCLUSION: The findings of this study suggest that CN deficiency is not an uncommon cause of congenital hearing loss. The findings that most ears with CN deficiency had normal IAC morphology and that two ears with small IACs had CNs present indicate that IAC morphology is an unreliable surrogate marker of CN integrity. On the basis of these findings, we think that high-resolution MRI, rather than CT imaging, should be performed in all cases of pediatric hearing loss, especially in those cases where profound hearing loss has been documented. For ears with small IACs, the resolution of MRI currently remains limiting. In these cases, the determination of CN status frequently requires a variety of anatomic (CT and MRI) and functional tests (auditory brainstem response, otoacoustic emissions, behavioral audiometry, and physical examination).     

Cochlear nerve size evaluation in children with sensorineural hearing loss by high-resolution magnetic resonance imaging

PURPOSE: To determine differences in size of cochlear nerves among subjects with deafness due to connexin 26 (Cx26) mutations, subjects with deafness of unknown origin, and normal hearing subjects by sagittal high-resolution magnetic resonance (HRMR) imaging of the temporal bone. MATERIALS AND METHODS: Cross-sectional and surface areas and volumetric measurements of the cochlear nerve and modiolus were made on HRMR images of the internal auditory canal (IAC) and inner ear in the 3 groups of children (groups 1, 2, and 3). Three-way comparisons of in vivo cochlear nerve measurements on HRMR imaging were made among 17 children with sensorineural hearing loss (SNHL) and no obvious etiology for the hearing loss (group 1), 7 children with profound SNHL due to a Cx26 mutation (group 2), and 10 normal hearing children (group 3). RESULTS: Children with profound SNHL of unknown cause and children with profound SNHL due to a connexin mutation displayed hypoplastic cochlear nerves as compared with normal controls. HRMR imaging of the temporal bone was accurately delineated potential problems with cochlear nerves in 2 of 17 instances where high-resolution computed tomography did not do so. CONCLUSIONS: Accurate and specific measurements of the cochlear nerve and related structures is possible on HRMR imaging of the temporal bone. The size of the cochlear nerve is mildly hypoplastic in children with profound SNHL of unknown causes or children with a deafness-causing Cx26 mutation. HRMR imaging is superior to high-resolution computed tomography in the investigation of profound SNHL in children.     

Evaluation of cochlear nerve imaging in severe congenital sensorineural hearing loss

The route of the cochlear nerve can be imaged using computed tomography (CT) or magnetic resonance imaging (MRI). To gain information about the cochlear nerve, we conducted a trial measuring the width of the cochlear nerve canal (CNC) using CT. When we examined images of the route of the cochlear nerve on MRI, both in ears with congenital sensorineural hearing loss (SNHL) and normal ones, we found that in ears in which the CNC was narrower than 1.5 mm with CT, images of cochlear nerve deficiency could be seen in that ear with MRI.     

1例耳蜗前庭神经畸形患者耳蜗植入术前的功能性磁共振评估并文献复习

目的:探讨功能性磁共振(fMRI)评价耳蜗前庭神经畸形患者是否有人工耳蜗植入指征的可能性。方法:对1例15岁双侧耳聋患者,在人工耳蜗植入前进行听力学、影像学检查及fMRI综合评估。结果:纯音测听和听觉脑干反应显示患者为双侧极重度感音神经性聋,瞬态诱发性耳声发射双侧均未引出。颞骨薄层CT显示内耳畸形(不全分隔Ⅰ型),MRI斜矢状位重建显示耳蜗前庭神经畸形。fMRI显示左耳给声,1000Hz100dBHL,右侧听皮层被激活;右耳给声,双侧听皮层均未见激活。左侧人工耳蜗植入术后1个月开机,患者对声音有反应。结论:结合听力学和影像学检查,fMRI可评估人工耳蜗植入候选者,尤其是在影像学检查显示患者耳蜗前庭神经发育畸形时,更是一种有效的评估方法。     

蜗神经磁共振成像在感音神经性聋中的应用

目的探讨蜗神经磁共振成像在感音神经性聋(SNHL)中的应用价值。方法采用GE TwinExct1.5T磁共振扫描仪对130例(260耳)SNHL患者进行蜗神经磁共振成像及内耳水成像。蜗神经成像序列为斜矢状位FRFSET2加权像,内耳水成像为3DFIESTA序列。结果 90例大于等于18岁的患者中,85例170耳显示蜗神经、迷路正常;1例2耳前庭导水管扩大;1例1耳蜗神经信号缺失;3例6耳蜗神经细小;40例小于18岁的患者中,19例38耳显示蜗神经、迷路正常;2例3耳Michel畸形;6例12耳Mondini畸形;1例2耳共腔畸形;12例24耳前庭导水管扩大;21例畸形中7例14耳蜗神经信号缺失。2例4耳显示内听道狭窄伴蜗神经细小。结论磁共振内耳成像对诊断SNHL有着重要的价值,对判断患者内耳蜗神经发育情况及内耳畸形有着不可替代的作用,是这类患者进行人工耳蜗植入术前必要检查。     

What is the site of origin of cochleovestibular schwannomas?

The belief that cochleovestibular schwannomas arise from the glial-Schwann cell junction has repeatedly been quoted in the literature, although there is no published evidence that supports this statement. A systematic evaluation of the nerve of origin and the precise location of cochleovestibular schwannomas using our respective archival temporal bone collections was conducted. Forty tumors were within the internal auditory canal (IAC), while 10 were intralabyrinthine neoplasms. Of the 40 IAC schwannomas, 4 arose from the cochlear nerve, and 36 from the vestibular nerve. Twenty-one tumors clearly arose lateral to the glial-Schwann cell junction, while 16 tumors filled at least two thirds of the IAC, with the epicenter of the neoplasm located in the mid part or the lateral part of the IAC. Only 3 schwannomas were located in the medial one third of the IAC in the area of the glial-Schwann cell junction. We concluded that cochleovestibular schwannomas may arise anywhere along the course of the axons of the eighth cranial nerve from the glial-Schwann sheath junction up until their terminations within the auditory and vestibular end organs.     

A case of unilateral sensorineural hearing loss caused by a venous malformation of the internal auditory canal

Intracranial vascular malformations can be classified as telangiectasis, varices, cavernous malformations, venous malformations (VMs), or arteriovenous malformations. VMs are congenital vascular malformations of the brain thought to be anomalies of the normal venous drainage. VMs are the most common intracranial vascular malformations documented by brain imaging and by autopsy series. However, vascular lesions of the internal auditory canal (IAC) are extremely rare. We report here a case of a VM arising within the IAC and expanding to the brainstem, causing a unilateral profound sensorineural hearing loss (SNHL). To the best of our knowledge, this is the first documented case of a VM as a rare cause of a unilateral SNHL in a child.     

A new classification for cochleovestibular malformations

OBJECTIVE: The report proposes a new classification system for inner ear malformations, based on radiological features of inner ear malformations reviewed in 23 patients. STUDY DESIGN: The investigation took the form of a retrospective review of computerized tomography findings relating to the temporal bone in 23 patients (13 male and 10 female patients) with inner ear malformations. The subjects were patients with profound bilateral sensorineural hearing loss who had all had high-resolution computed tomography (CT) with contiguous 1-mm-thick images obtained through the petrous bone in axial sections. METHODS: The CT results were reviewed for malformations of bony otic capsule under the following subgroups: cochlear, vestibular, semicircular canal, internal auditory canal (IAC), and vestibular and cochlear aqueduct malformations. Cochlear malformations were classified as Michel deformity, common cavity deformity, cochlear aplasia, hypoplastic cochlea, incomplete partition types I (IP-I) and II (IP-II) (Mondini deformity). Incomplete partition type I (cystic cochleovestibular malformation) is defined as a malformation in which the cochlea lacks the entire modiolus and cribriform area, resulting in a cystic appearance, and there is an accompanying large cystic vestibule. In IP-II (the Mondini deformity), there is a cochlea consisting of 1.5 turns (in which the middle and apical turns coalesce to form a cystic apex) accompanied by a dilated vestibule and enlarged vestibular aqueduct. RESULTS: Four patients demonstrated anomalies involving only one inner ear component. All the remaining patients had diseases or conditions affecting more than one inner ear component. Eight ears had IP-I, and 10 patients had IP-II. Ears with IP-I had large cystic vestibules, whereas the amount of dilation was minimal in patients with IP-II. The majority of the semicircular canals (67%) were normal. Semicircular canal aplasia accompanied cases of Michel deformity, cochlear hypoplasia, and common cavity. In 14 ears, the IAC had a defective fundus at the lateral end. In two ears the IAC was absent. In all seven cases of common cavity malformations, there was a bony defect at the lateral end of the IAC. In five of them the IAC was enlarged, whereas in two the IAC was narrow. All patients with IP-I had an enlarged IAC, whereas in patients with type II disease, four had a normal IAC and 10 had an enlarged IAC. All cases of IP-II had an enlarged vestibular aqueduct, whereas this finding was not present in any of the cases of IP-I. In all cases, the vestibular aqueduct findings were symmetrical on both sides (simultaneously normal or enlarged). No patient demonstrated enlargement or any other abnormalities involving the cochlear aqueduct. CONCLUSIONS: Radiological findings of congenital malformations in the present study suggested two different types of incomplete partition. Cystic cochleovestibular malformation (IP-I) and the classic Mondini deformity (IP-II). The type I malformation is less differentiated than the type II malformation. Classic Mondini deformity has three components (a cystic apex, dilated vestibule, and large vestibular aqueduct), whereas type I malformation has an empty, cystic cochlea and vestibule without an enlarged vestibular aqueduct. Mondini deformity represents a later malformation, so the amount of dysplasia is much less than in type II. Therefore, it is more accurate and useful for clinical purposes to classify these malformations (in descending order of severity) as follows: Michel deformity, cochlear aplasia, common cavity, IP-I (cystic cochleovestibular malformation), cochlear hypoplasia, and IP-II (Mondini deformity). Only in this way can these complex malformations be grouped precisely and the results of cochlear implantation compared.     

内听道海绵状血管瘤的临床资料分析

摘要：目的探讨内听道海绵状血管瘤的诊断和治疗方法。方法回顾性分析2006年1月~2013年12月6例内听道海绵状血管瘤患者的临床资料,对患者的临床表现、影像学表现、手术方法及效果进行分析。6例患者均进行了CT与MRI检查,其中5例患者伴有面神经功能障碍,对此5例患者进行了手术治疗,对1例面神经功能正常的患者采取严密随访策略。结果6例患者术前均出现了听力下降与耳鸣,其中5例手术患者病理确诊为内听道海绵状血管瘤。手术径路包括4例迷路径路与1例颅中窝径路,术中发现肿瘤与面神经和（或）前庭蜗神经粘连,难以分离,其中3例由于肿瘤无法与面神经分离行面神经切除重建术,2例患者面神经解剖保留。术后5例患者患侧听力均丧失,术后1年行MRI复查肿瘤无残留,面神经功能均有不同程度提高。随访患者行MRI检查示肿瘤未生长。结论内听道海绵状血管瘤术前可以根据临床表现与特征性影像学表现作出诊断;相较于内听道其他常见肿瘤,海绵状血管瘤更易侵犯神经,因此手术时机的选择应更加积极;迷路径路相较于乙状窦后径路或颅中窝径路在处理内听道海绵状血管瘤上有优势,比较容易进行面神经定位与重建。     

Contemporary surgical issues in paediatric cochlear implantation

Abstract

Objective: To review the contemporary surgical issues in paediatric cochlear implantation (CI) based on published evidence. Design: Narrative literature review. Results: Surgical challenges in paediatric CI are discussed, with respect to post meningitic labyrinthitis ossificans; cochlear malformation; cochlear implantation in infants; auditory neuropathy and cochlear nerve deficiency; bilateral cochlear implantation; hearing preservation; otitis media; and device failure. Conclusion: Early CI is recommended if bacterial meningitis causes profound sensorineural hearing loss (SNHL). CI in cochleovestibular malformation requires pre-operative imaging to plan surgical technique, choice of electrode, and to anticipate complication. Children with congenital severe to profound SNHL should undergo early bilateral simultaneous implantation, preferably before 12 months of age, except those with auditory neuropathy spectrum disorder who should be implanted after one year. Soft surgical technique should be deployed in an attempt to preserve any residual hearing. Otitis media with effusion is not a contraindication to cochlear implantation, but active or recurrent acute otitis media requires resolution of infection with grommet insertion pre-operatively. Device failure in CI recipients requires a stepwise audiological, medical, radiological, and device integrity assessment to determine the need for reimplantation.