Bilateral narrow duplicated internal auditory canal

Internal auditory canal (IAC) anomalies are rare malformations that may include alterations of shape, size or orientation of the IAC. Bilateral duplication of IAC is a very rare malformation and only one case has been described in literature. We report a case of bilateral duplicated IAC together with other inner ear anomalies.     

Clinical review of inner ear malformation

We had 126 patients with inner ear malformation diagnosed with temporal bone computed tomography (CT) scans at Azabu Triology Hospital between 1996 and 2002. We classified cases of inner ear malformation according to Jackler et al. The incidence of inner ear malformation in our series was as follows; 1. Labyrynthine anomalies 61% (isolated lateral semicircular canal dysplasia 56%, compound semicircular canal dysplasia 4%, semicircular canal aplasia 1%), 2. Cochlear anomalies 24%, 3. Enlargement of the vestibular aqueduct 12%, 4. Narrow internal auditory canal 2%, 5. Complete labyrinthine aplasia 1%, 6. Enlargement of the cochlear aqueduct 0%. The most frequent anomaly was isolated lateral semicircular canal dysplasia. We did not detect any significant clinical features in this anomaly. There were 2 patients with cochlear anomalies who had past histories of meningitis. Some patients with enlargement of the vestibular aqueduct had frequent attacks of fluctuating hearing. Clinically it is important to detect patients with inner ear malformation such as cochlear anomalies and enlargement of the vestibular aqueduct usually accompanied by congenital sensorineural hearing loss. For patients with congenital sensorineural hearing loss, we recommend temporal bone CT scan.     

Diagnosis and operative sequela of rare abnormalities of the inner ear

Two cases of congenital unilateral deafness in otherwise normal children are presented. X-ray examination showed a partition of the inner ear canal in one of them. A review of the literature showed this lesion to be very rare, but it is more frequent in combination with other malformations such as the Klippel-Feil-syndrome, Wildervanck-syndrome and Thalidomide embryopathy. The second child showed an extensive malformation of the cochlear and vestibular parts of the inner ear and of the internal auditory meatus. The vestibulocochlear nerve was absent. An arachnoidal cyst protruding into the tympanic cavity formed the only boundary between the middle ear and the cerebrospinal fluid. This resulted in relapsing meningitis and a postmeningitic hearing loss on the other side. A tympanoscopy and closure of the connection between the tympanic cavity and the internal auditory meatus stopped the ascending infections.     

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.     

内耳结构异常的语前聋人工耳蜗植入儿童听觉语言康复效果评价

目的评价不同类型内耳结构异常的语前聋儿童人工耳蜗植入术后听觉语言康复效果。方法选取人工耳蜗植入儿童10例(12耳),其中内耳结构发育正常的3例,前庭导水管扩大3例,Mondini畸形1例,蜗孔狭窄1例,内听道狭窄听神经纤细2例,分别采用电刺激诱发听神经复合动作电位(electrically evoked compound action potential,eCAP)、助听听阈、听障儿童听觉能力、语言能力评估标准及方法,从听神经客观电生理水平、听察觉阈、听觉辨识与理解能力以及语言能力4方面评价患儿的康复效果。结果①客观电生理:单纯前庭导水管扩大患者听神经对电刺激敏感度与内耳发育正常者相似,Mondini畸形患者比内耳发育正常者略高,蜗孔狭窄及听神经纤细患者听神经敏感度较差;②听察觉阈:与内耳结构正常及轻度畸形(Mondini畸形)患者相比,蜗孔狭窄及听神经纤细患者听察觉阈偏高,高频比低频阈值低;③听觉辨识与理解能力:在安静环境近距离交谈情境下,单纯前庭导水管扩大、Mondini畸形及蜗孔狭窄患者对熟悉语词和短句的辨识与理解能力与内耳发育正常者无差别,听神经纤细患者得分较低;④语言能力:单纯前庭导水管扩大、Mondini畸形患者与内耳发育正常者无差别,蜗孔狭窄患者的语言交往与表达能力落后于内耳发育正常者,听神经纤细患者在语法、理解、交往、表达4个维度均落后于内耳发育正常者。结论语前聋儿童人工耳蜗植入术后听觉语言康复效果需要使用多种方法综合评价。Mondini畸形患者给予足够电刺激量后,其听觉语言能力可达到内耳发育正常者水平。蜗孔狭窄、听神经纤细等严重内耳畸形患者,人工耳蜗对其听觉语言能力发展有一定帮助,家长需要建立合理期望值并坚持长期康复。     

双内听道的影像学特征

目的 总结双内听道(duplication of internal auditory canal,DIAC)的多层螺旋CT和MRI影像学特点,提高对该病的认识.方法 结合文献回顾性分析4例(5耳)DIAC患者的影像学资料,4例均行多层螺旋CT检查,其中2例同时行MRI检查.结果 多层螺旋CT显示5耳内听道被骨性间隔分为双管状,上部骨管与面神经管相连,下部骨管与前庭和耳蜗相连,其中2耳骨性间隔不完整.5耳上下两管径之和均超过2 mm.3耳可显示蜗神经管狭窄.5耳均合并前庭扩大及外半规管发育不良,2例(2耳)同时合并小耳廓畸形,1耳合并小耳廓畸形、外耳道闭锁及听小骨发育不良.多平面重建(multiplanar reconstruction)、容积再现(volume rendering)图像可全面立体显示骨性间隔及双管结构.MRI显示1耳前庭和蜗神经发育不良、面神经完好,另1耳前庭、蜗神经和面神经均发育不良.结论 多层螺旋CT能清晰显示内听道被骨性间隔分为双管状及伴发畸形,可作为确诊DIAC的依据.MRI能表示其神经发育异常,为电子耳蜗植入对象的选择提供一定帮助.     

普遍新生儿听力筛查中确诊耳聋者颞骨CT的影像学分析

目的：探讨普遍新生儿听力筛查中确诊为耳聋的婴幼儿颞骨高分辨率CT（HRCT）的影像学表现,以及对耳聋原因诊断的作用。方法：2005年1～12月,121400名新生儿参加上海市新生儿听力筛查,1077例2次筛查阳性者转至上海市儿童听力障碍诊治中心进一步行诊断性听力检查,其中184例被确诊为先天性聋的患儿接受颞骨HRCT检查,对此资料进行分析研究。结果：184例先天性聋患儿中颞骨HRCT发现解剖畸形者58例（31．5％）,其中外耳畸形26例（44．8％）,中耳畸形21例（36．2％）,内耳畸形31例（53．4％）。内耳畸形包括Mondini畸形12例,共同腔畸形1例,前庭导水管扩大、不伴耳蜗畸形6例,前庭、半规管畸形10例,内听道异常5例。另外,单纯鼓室积液20例（10．8％）。结论：HRCT检查对婴幼儿耳聋原因的鉴别诊断和治疗有一定帮助。     

Congenital facial palsy and ipsilateral deafness: Association with maternal diabetes mellitus

Congenital facial palsy and ipsilateral deafness were found in two children of unrelated insulin-requiring diabetics. Multidirectional tomography showed hypoplasia of the internal auditory canal in each case but the cochlea, vestibule and semicircular canals were radiologically normal. The malformation in these patients must have been determined before 23 weeks of gestational age when ossification of the inner ear is complete. The association of this malformation and maternal diabetes is unlikely to be coincidental.     

Histopathological study of the temporal bones in patients with primary carcinomas of the ear

The most common symptoms of patients with carcinomas of the middle ear or mastoid are otorrhea, facial paralysis, and hearing loss, including a sensorineural element and vertigo. The latter two symptoms are indicators of inner ear damage. However, few reports have been made concerning the histopathological changes that occur in the inner ear in the presence of a tumor. The present study was performed to determine the pattern of tumor invasion in the inner ear and the histopathological changes that occur in the inner ear in cases of ear carcinomas. Temporal bone sections from five patients (age: #39-73 years; 3 males and 2 females) who died from a primary carcinoma of the ear were studied histologically. The following features were examined: 1) localization of the tumor in the temporal bone, 2) pattern of tumor invasion in the inner ear, 3) pathological changes in the inner ear, including the cochlea, vestibule and semicircular canals. Tumor cells were still present in the temporal bone sections of all the patients except one, even though the patients had received various treatments for the carcinoma, including radiation therapy, surgery and chemotherapy. Marked inflammatory and necrotic changes were observed in cases where the tumor had invaded the external auditory canal, middle ear cleft, internal auditory canal, and in some cases the inner ear. In cases where the tumor invaded the inner ear via the internal auditory canal rather than directly from the middle ear, the otic capsule is thought to have acted as a barrier against tumor invasion. In addition, marked degenerative changes throughout the entire inner ear structures were noted. These changes may have arisen from an attenuated blood supply to the inner ear as a result of pressure from the tumor in the internal auditory canal, tumor infiltration of the labyrinthine artery.     

共同腔畸形人工耳蜗手术适应证及手术方法的探讨

目的：探讨共同腔畸形人工耳蜗手术适应证以及人工耳蜗电极植入人路的选择。方法：在对重度或全聋患者进行人工耳蜗植入术前影像掌检查中,发现了6例耳蜗、前庭、外半规管呈共同腔畸形,其中5例有残留听力,1例未查到残留听力。结果：6例影像学检查呈共同腔畸形患者中,对5例有残留听力患者进行了人工耳蜗植入,其中3例选择了常规入路植入电极,2例选择了经乳突侧入路植入电极,术后均建立了人工耳蜗的听觉反应。1例因未查到残留听力,放弃了人工耳蜗手术治疗。结论：有残留听力的共同腔畸形患者,如果能够接受术后听觉言语识别效果差的事实,可以进行人工耳蜗手术。无残留听力或无法了解到有听觉反应的共同腔畸形患者,在现有技术条件下应放弃人工耳蜗植入手术。     

Kochleaimplantat bei Innenohrfehlbildungen

The radiologic evaluation of the temporal bone in cochlear implant candidates can detect malformations of the inner ear in up to 20% of cases. The aim of our study was to analyze and classify malformations of the inner ear in patients with cochlear implants carried out from 2001 to 2009. Malformations of the inner ear, including malformations of the internal auditory canal were detected in 12.7% of children and 3.4% of adults. Mondini dysplasia was most common and occurred in 45% of cases. The surgical procedure had to be adapted according to the individual malformation. Modification of surgical access, management of intraoperative CSF gusher, choice of electrode array, intraoperative imaging and the use of navigation were the most important factors. Rehabilitation results were generally very positive and corresponded to the expectation depending on the duration of deafness, if no additional handicaps were present.     

Mycotic infections of the inner ear

Mycotic infections of the inner ear have only rarely been reported. In each reported case, involvement of the inner ear appeared to be secondary to overwhelming central nervous system disease. A review of specimens from the University of Minnesota temporal bone collection has identified three distinct routes of inner ear involvement by fungi suggesting the potential pathogenesis for this disease to be similar to that identified for bacterial labyrinthitis (tympanogenic, meningogenic, hematogenic). The first case, a 48-year-old white male with leukemia, died of mucor meningoencephalitis. Temporal bone study revealed Mucor sp. in the arterioles of the temporal bone as well as fungal involvement of the perilymphatic space secondary to round window invasion, oval window invasion, and invasion through the internal auditory canal. The second case was a 69-year-old white male, diabetic, who died of Klebsiella septicemia. Post mortem temporal bone study revealed a focus of Candida sp. in the vestibule under the stapedial footplate without apparent involvement of the internal auditory canal. Case 3 was a 16-year-old male with lymphosarcoma who died of septicemia and candida meningoencephalitis. Candida sp. could be seen in the scala tympani adjacent to Rosenthal's canals presumably secondary to spread from the central nervous system. The fourth case, that of a 28-year-old white female with systemic candidiasis, had sequential ante mortem audiograms demonstrating progressive bilateral sensorineural hearing loss. Post mortem histologic examination of the temporal bones identified candida involvement of the inner ear which appeared to be hematogenic in origin. These four cases demonstrate conclusive examples of inner ear involvement of fungal disease by the tympanogenic, meningogenic, and hematogenic routes.     

内耳畸形聋儿人工耳蜗植入术常见类型及手术并发症

目的 探讨内耳畸形聋儿实施人工耳蜗植入术时常见的类型及并发症。方法 回顾性分析电子耳蜗植入术病历资料170例,对其中的32例双侧内耳畸形患者加以畸形类型及手术并发症总结。结果 ①人工耳蜗植入患儿内耳畸形所占比例(32/170,18.8%)明显高于其他文献报道;②32例内耳畸形中,大前庭导水管23例(占全部畸形数71.3%),大前庭导水管伴其他类型畸形者5例(并发Mondini畸形4例,并发外半规管未发育1例),Mondini畸形2例,Mondini畸形并发外半规管未发育前庭腔扩大1例,耳蜗CT影像疑似为“三叉”无法分类1例;③术中发生严重井喷3例(耳蜗CT影像疑似为“三叉”畸形、Mondini畸形并发外半规管未发育前庭腔扩大1例,及大前庭导水管并发Mondini畸形1例);④耳蜗影像疑似为“三叉”患者,术中发生严重井喷,电极植入困难,4个电极不能植入,术后听力未改善,半年后行对侧耳植入成功;⑤Mondini畸形并发外半规管未发育前庭腔扩大患儿术后半年并发脑脊液耳鼻漏、反复脑膜炎发作,术后1年行手术探查,后治愈。结论 ①人工耳蜗植入常见的内耳畸形包括,大前庭导水管综合征及其相伴发或单发的各类内耳畸形;②内耳畸形非人工耳蜗植入术的绝对禁忌证,但术中严重井喷多见,电极植入不完全多见,术后脑脊液耳鼻漏并发脑膜炎也多发生于畸形耳蜗,术前详细的影像学检查可以对各类畸形进行详细分类,并在术前对手术难度有充分的准备,可以减少相关并发症的发生。     

Amyloidosis of the external auditory canal and middle ear: unusual ear tumor

Amyloidosis of the ear is rare. We describe the case of a 41-year-old man who had localized amyloidosis that involved the external auditory canal and middle ear. To the best of our knowledge, only 4 other cases of amyloidosis involving the external auditory canal have been previously reported; in none of these cases was the middle ear involved. We also discuss the clinical importance of this condition and its treatment.     

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。     

Angiomatous malformation of the inner auditory canal with the leading symptoms of vertigo and tinnitus

A case of a rare arteriovenous malformation in the internal auditory canal is reported. It caused unilateral tinnitus, facial weakness, trigeminal hypesthesia, and vertigo with lateropulsion. The audiological and otoneurological findings together with air-cisternography a CT scan had indicated an intrameatal tumor. An extended trans-temporal exposure of the internal auditory canal demonstrated an angiomatous lesion compressing the adjacent seventh and eighth cranial nerves. It could be removed safely by a second-stage lateral suboccipital approach to the cerebello-pontine angle.     

Anteverted internal auditory canal as an inner ear anomaly in patients with craniofacial microsomia

Craniofacial microsomia involves structure of the first and second branchial arches. A wide range of ear anomalies, affecting external, middle and inner ear, has been described in association with this condition. We report three cases of anteverted internal auditory canal in patients presenting craniofacial microsomia. This unique internal auditory canal orientation was found on high-resolution computed tomography of the temporal bones. This internal auditory canal anomaly is yet unreported in craniofacial anomalies.     

45例先天性内耳畸形的高分辨率CT特征

目的：探讨先天性内耳畸形的高分辨率CT(HRCT)特征及其在先天性内耳畸形诊治中的意义。方法：总结45例先天性内耳畸形的临床资料．分析颞骨HRCT所见。结果：45例耳聋多起于幼儿．呈缓慢进行性感音神经性听力减退，波动性者15耳；17耳半规管麻痹。HRCT显示：Michel型3例(4耳)；Mondini型25例(39耳)；不伴内耳畸形的前庭水管扩大13例(23耳)；内耳道发育畸形4例(5耳)。伴中、外耳畸形13耳。结论：HRCT对先天性内耳畸形具有重要的诊断价值，并为临床治疗、特别是人工耳蜗植入术适应证的选择提供了重要的依据。     

HRCT imaging characterized of congenital abnormalities of the inner ear in 45 cases]

OBJECTIVE: To explore the high resolution CT (HRCT) image characterized of congenital abnormalities of the inner ear(CAIE), and its value in the diagnosis and treatment of CAIE. METHOD: The clinic data and axial HRCT scans of CAIE in 45 cases were analyzed. RESULT: In 45 CAIE patients, most of them were frequently associated with slowly progressive sensorineural hearing loss in childhood, 15 ears were fluctuating hearing loss. Seventeen ears were unilateral semicircular canal paralysis. HRCT showed that Michel type 3 cases(4 ears), Mondini type 25 cases(39 ears). Large vestibular aqueduct malformation not associated with anomalies of inner ears 13 cases(23 ears), anomalies of internal auditory canal 4 cases (5 ears). Thirteen ears were associated with outer and middle ear malformation. CONCLUSION: HRCT image has the important value in the diagnosis and treatment of CAIE, especially for the excerpt of indication of cochlear implantation.     

Patulous internal auditory canal

OBJECTIVE: To investigate a rare anomaly of the internal auditory canal known as a patulous canal and its relationship to hearing impairment. METHODS: High-resolution computed tomographic scans of the temporal bones of patients who presented between August 2001 and August 2002 were reviewed. The patients' medical charts were evaluated for age, sex, and hearing impairment, and the computed tomographic scans were examined for the presence of a patulous canal. RESULTS: The study group included 645 patients who underwent high-resolution computed tomography of the temporal bones for various reasons, including sensorineural hearing loss (50% of patients). A patulous canal without any associated anomaly of the labyrinth was the only finding in 2 patients. Both patients had chronic middle ear disease along with conductive hearing loss. CONCLUSION: Patulous canal is a rare anatomical variant of the internal auditory canal (0.3%), and its association with inflammatory ear disease accompanied by conductive hearing impairment appears to have been incidental in both cases in the present study.