Volume of components of labyrinth: magnetic resonance imaging study.

OBJECTIVE: To determine total inner ear fluid volume and cochlear and semicircular canal/vestibule volumes of a normal population to form a base for dimensional abnormalities of inner ear structures. STUDY DESIGN: Cross-sectional. SETTING: Academic otology and radiology practices. PATIENTS: Twenty-nine healthy volunteers (13 male patients and 16 female patients with an average age of 31 yr) without any known history of intrauterine infection or any exposure to ototoxic agents and no abnormality at physical examination from the standpoint of hearing loss were included. INTERVENTIONS: Twenty-nine volunteers underwent magnetic resonance imaging of the temporal region by means of thin-section T2-weighted sequences. The images were evaluated by the radiologist for the presence of any gross configurational abnormality. Fluid volume of each inner ear and components of labyrinth (cochlea, semicircular canals/vestibule) were calculated with the help of an online work station. MAIN OUTCOME MEASURE: To determine the volume of components of the labyrinth and total inner ear fluid, which may form a base for future studies about sensorineural hearing loss. RESULTS: The volumes of total inner ear fluid, cochlea, and semicircular canals/vestibule were calculated. The mean and standard deviation of total inner ear fluid volume, cochlear volume, and semicircular canal/vestibule volume were obtained for each volunteer. Results were assessed with the help of statistical tests. CONCLUSION: There was no statistically significant difference between right and left inner ear fluid volumes of male and female subjects. There was also no statistical difference between right and left inner ear volumes when age and sex were not concerned. During evaluation of volumes according to sex, the difference between right and left inner ear fluid volumes was also assessed. Left semicircular canal/vestibule volume of female subjects were found to be higher than that of male subjects. The difference between right and left semicircular canal/vestibule volumes of female subjects was higher than the difference between right and left semicircular canal/vestibule volumes of male subjects.     

Position and variations in the position of the canal system in the temporal bone. I. The canals of the pars petrosa between the margo superior and the meatus acusticus internus

The canals of the temporal bone were measured on 103 objects at different levels. The distances (mean and extremes) were estimated as well as the width of the following: the facial canal, semicircular canals, vestibule, internal acoustic meatus, sigmoid sinus, superior bulb of the jugular vein, carotid canal, eustachian tube, perilymphatic and endolymphatic ducts and sac, glossopharyngeal nerve and mastoid cells.     

Identification of previously "undetectable" abnormalities of the bony labyrinth with computed tomography measurement

BACKGROUND: In patients with congenital sensorineural hearing loss (SNHL), a computed tomography (CT) scan of the temporal bone identifies inner ear malformations in approximately 25%, whereas the inner ear is grossly normal to visual inspection in the remaining 75% of the patients. In the latter group, the hearing loss is often attributed to radiologically undetectable abnormalities of the membranous labyrinth. However, subtle bony malformations may be missed because visual inspection alone is insensitive for detection. OBJECTIVE: To test the hypothesis that there are subtle bony abnormalities of the inner ear in patients with SNHL who are radiologically deemed to have normal otic bone, using standardized measurements of the inner ear. STUDY DESIGN: Retrospective review. METHODS: Measurements of the cochlea, vestibule, and semicircular canals (SCCs) were made on axial and coronal temporal bone CT scans on 15 patients with normal hearing and 15 patients with congenital SNHL and grossly normal temporal bone CT scans. Student's t-test was performed to compare the measurements of the two groups.RESULTS All studies from the SNHL group were deemed normal by visual inspection and standardized measurements (+/-2 SD from normal). Surprisingly, there were significant differences in the measurements of the cochlea and of the SCCs between patients with and without SHNL (P <.05). CONCLUSIONS: As a group, patients with SNHL and a "normal CT scan" have significant differences in the dimensions of the inner ear. This suggests that these patients have disturbed morphogenesis of both membranous and bony labyrinth. This novel observation has important implications for understanding the etiology of SNHL.     

Anatomic study of maximum intensity projection of the membranous labyrinth and the internal auditory meatus - MRI scan in 16 Chinese adults

CONCLUSION: Three-dimensional reconstruction of maximum intensity projection (MIP) might document objectively, stereoscopically and directly the minute structures of the membranous labyrinth and internal auditory meatus. In this study, we establish magnetic resonance imaging (MRI) measurement criteria of the inner ear in Chinese adults. OBJECTIVE: The goal of this study was to provide an anatomic basis for otolosurgery and neurosurgery in Chinese adults. MATERIALS AND METHODS: Sixteen healthy volunteer subjects were scanned by a GE-signa 1.5T MRI scanner. All original images were transferred to an MRI workstation and all the structures of the inner ear were reconstructed, rotated at various angles and measured with an MIP program. RESULTS: Anatomic structures of the membranous labyrinth and internal auditory meatus were well demonstrated in MIP images in all volunteers. All inner ear structures including utricle, saccule, cochlear duct, internal auditory meatus and three semicircular ducts produced high intensity signals.     

Inner ear malformations with oto-liquorrhea. Tomographic findings in three cases with a mixed hearing impairment

The paper deals with three boys suffering from a mixed hearing loss. They were all referred to tomography of the temporal bones in order to find some middle ear malformation amenable to surgery. The tomograms revealed identical malformations of the inner ear; the lumen of the labyrinth are found irregularly dilated and the internal acoustic meatus is widened. Its course in the lateral end is abnormal with a downwards turn towards the basal coil of the cochlea. Explorative tympanotomy in one of the patients revealed a severe otoliquorrhea during an attempt to perform a stapedectomy, and this may serve as a warning against operation in patients presenting the mentioned tomographic changes which, once seen, are easily recognized.     

Anatomic study of maximum intensity projection of the membranous labyrinth and the internal auditory meatus – MRI scan in 16 Chinese adults

Conclusion. Three-dimensional reconstruction of maximum intensity projection (MIP) might document objectively, stereoscopically and directly the minute structures of the membranous labyrinth and internal auditory meatus. In this study, we establish magnetic resonance imaging (MRI) measurement criteria of the inner ear in Chinese adults. Objective. The goal of this study was to provide an anatomic basis for otolosurgery and neurosurgery in Chinese adults. Materials and methods. Sixteen healthy volunteer subjects were scanned by a GE-signa 1.5T MRI scanner. All original images were transferred to an MRI workstation and all the structures of the inner ear were reconstructed, rotated at various angles and measured with an MIP program. Results. Anatomic structures of the membranous labyrinth and internal auditory meatus were well demonstrated in MIP images in all volunteers. All inner ear structures including utricle, saccule, cochlear duct, internal auditory meatus and three semicircular ducts produced high intensity signals.     

Magnetic resonance imaging virtual endoscopy of the labyrinth

OBJECTIVE: To explore the feasibility of applying virtual endoscopic (VE) techniques to examine the normal anatomy of the labyrinth using magnetic resonance imaging (MRI) data. STUDY DESIGN: Feasibility study using data from a normal subject. MATERIALS AND METHODS: MRI data was acquired in a single normal subject using a three-dimensional (3D) CISS (Constructive Interference in the Steady State) sequence. Perspective volume rendering (PVR) techniques were used to produce virtual endoscopic visualization of the fluid filled structures of the inner ear. RESULTS: The reconstructive algorithms enabled generation of a "fly-through" simulation of the labyrinth. The cochlea, the oval window, the vestibule, the common crus, and the semicircular canals were successfully visualized. CONCLUSIONS: Virtual endoscopic techniques were successfully applied to MRI data enabling a 3D virtual display of the internal anatomy of the normal labyrinth.     

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.     

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。     

Measurements of normal inner ear on computed tomography in children with congenital sensorineural hearing loss

The objective of this study is to use standardized measurements of the inner ear to see whether there are subtle bony malformations in children with congenital sensorineural hearing loss (SNHL) whose temporal bone computed tomography (CT) are grossly normal. The study includes 45 ears with congenital SNHL and grossly normal temporal bone CT scans and 45 ears with normal inner ear structures and normal hearing. Standardized measurements of the inner ear structures were made on axial temporal bone CT scans. Student’s t test was performed to compare the measurements of the two groups. There were significant differences in the measurements of the bony island width of the superior semicircular canal, bony island width of the lateral semicircular canal and maximal height of cochlea between two groups (P < 0.05). In conclusion, standardized measurements of bony labyrinth of inner ear on temporal bone CT can identify subtle abnormalities of inner ear in patients with congenital SNHL having grossly normal radiological images.     

Inner ear anatomy in Waardenburg syndrome: Radiological assessment and comparison with normative data

Objective

As patients with Waardenburg syndrome (WS) represent potential candidates for cochlear implantation, their inner ear anatomy is of high significance. There is an ongoing debate whether WS is related to any inner ear dysplasias. Our objective was to evaluate radiologically the inner ear anatomy in patients with WS and identify any temporal bone malformations.

Methods

A retrospective case review was carried out in a tertiary, referral center. The high resolution computed tomography (HRCT) scans of the temporal bone from 20 patients (40 ears) with WS who were managed for deafness in a tertiary referral center from 1995 to 2012 were retrospectively examined. Measurements of 15 different inner ear dimensions, involving the cochlea, the vestibule, the semicircular canals and the internal auditory meatus, as well as measurements of the vestibular aqueduct, were performed independently by two neuroradiologists. Finally, we compared the results from the WS group with a control group consisting of 50 normal hearing subjects (100 ears) and with previously reported normative values.

Results

Inner ear malformations were not found in any of the patients with WS. All measured inner ear dimensions were within the normative values compiled by our study group as well as by others.

Conclusions

Inner ear malformations are not characteristic for all types of WS; however, certain rare subtypes might be related to inner ear deformities. Normative cochleovestibular dimensions that can help in assessing the temporal bone anatomy are provided.     

Computed tomography demonstrates abnormalities of contralateral ear in subjects with unilateral sensorineural hearing loss

Purpose

Prior studies have associated gross inner ear abnormalities with pediatric sensorineural hearing loss (SNHL) using computed tomography (CT). No studies to date have specifically investigated morphologic inner ear abnormalities involving the contralateral unaffected ear in patients with unilateral SNHL. The purpose of this study is to evaluate contralateral inner ear structures of subjects with unilateral SNHL but no grossly abnormal findings on CT.

Materials and methods

IRB-approved retrospective analysis of pediatric temporal bone CT scans. 97 temporal bone CT scans, previously interpreted as “normal” based upon previously accepted guidelines by board certified neuroradiologists, were assessed using 12 measurements of the semicircular canals, cochlea and vestibule. The control-group consisted of 72 “normal” temporal bone CTs with underlying SNHL in the subject excluded. The study-group consisted of 25 normal-hearing contralateral temporal bones in subjects with unilateral SNHL. Multivariate analysis of covariance (MANCOVA) was then conducted to evaluate for differences between the study and control group.

Results

Cochlea basal turn lumen width was significantly greater in magnitude and central lucency of the lateral semicircular canal bony island was significantly lower in density for audiometrically normal ears of subjects with unilateral SNHL compared to controls.

Conclusion

Abnormalities of the inner ear were present in the contralateral audiometrically normal ears of subjects with unilateral SNHL. These data suggest that patients with unilateral SNHL may have a more pervasive disease process that results in abnormalities of both ears. The findings of a cochlea basal turn lumen width disparity >5% from “normal” and/or a lateral semicircular canal bony island central lucency disparity of >5% from “normal” may indicate inherent risk to the contralateral unaffected ear in pediatric patients with unilateral sensorineural hearing loss.     

Labyrinthine lesions in presumed inner ear hemorrhage-related sudden deafness

PurposeInner ear hemorrhage (IEH) is a rare cause of sudden sensorineural hearing loss (SSNHL). This study aimed to evaluate the lesional patterns in patients with presumed IEH from morphological and functional aspects.MethodsSeventeen patients with SSNHL and presumed IEH who completed audio-vestibular tests were included. The main outcome measures included clinical characteristics, radiology, and functional test results.ResultsThe morphological findings and functional tests revealed differences in locations and lesional spectrums. The magnetic resonance imaging (MRI) hyperintensity was likely to involve the vestibule (88.2%), the cochlea (76.5%), and the posterior and lateral semicircular canals (76.5% and 70.6%, respectively). Furthermore, 70.6% of cases showed abnormality in the entire labyrinth, and abnormalities in the vestibule/semicircular canals were observed in 17.6% of cases. Meanwhile, dysfunction was sequentially detected in the cochlea (100%), semicircular canals (94.1%), and vestibule (70.6%); 64.7% of cases showed combined deficit in the entire labyrinth, and 29.4% of cases showed combined deficit in the cochlea/semicircular canals. Although lesions in the labyrinth were frequently detected, the results of the radiological and functional tests did not always match and significantly differed in either cochlear or superior semicircular canal damage detection (p < 0.05 each).ConclusionsIn this cohort, IEH preferentially caused sudden audio-vestibular impairment, which was well demonstrated by a combination of MRI and functional tests. The specific lesional configurations revealed in this study may suggest a possible pathomechanism that could be further explored as a therapeutic target.     

Acoustic neurinomas presenting as middle ear tumors

Since the advent of the widespread use of the operating microscope and the excellent graduate and post-graduate training in otology, more and more otosurgeons are exploring disease of the middle and inner ear; consequently, more and more unusual and varied anomalies and tumors are being described. This paper describes the unusual presentation of acoustic neurinomas in the middle ear. Most acoustic nerve tumors arise within the meatus of the internal auditory canal, producing the syndrome of the cerebellopontine angle. In the first case presented, the tumor did not arise in the usual location, and this points out the fact that acoustic nerve tumors may arise anywhere along the course of the VIIIth nerve. It is felt that the tumor must have arisen in one of the smaller branches of the inferior vestibular nerve, lateral to the vestibule, as it did not extend medially beyond the medial wall of the vestibule. Instead, it presented in the cochlear windows as a middle ear tumor. In the second case, the tumor apparently arose in the usual location, in the meatus of the internal auditory canal. Its lateral extension was unusual, in that the tumor filled the entire labyrinth and presented as a middle ear tumor in the cochlear windows of the middle ear, and its extension medially, produced the classical findings of the cerebellopontine angle tumor.     

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.     

内耳及毗邻结构三维形态学研究

目的基于颞骨CT三维重建,研究内耳及其毗邻结构的三维解剖关系,对内耳及其毗邻结构的空间立体关系进行测量定位,总结规律,为指导耳科及侧颅底手术提供参考。方法使用3D-DOCTOR软件对34例成人颞骨轴位CT影像进行三维重建,显示内耳及其毗邻各重要结构的形态及其相互间复杂的空间关系。并用软件自带的功能测量内耳及其毗邻结构之间的距离和相对角度,总结内耳及其毗邻各重要结构的距离及相对角度的规律性。结果重建获得了清晰的耳蜗、半规管、听小骨、面神经、内听道、颈静脉球窝、颈内动脉管等颞骨内重要结构三维图象。测量三维模型后准确获得了耳蜗及半规管与面神经、颈内动脉、颈静脉球之间相对关系的参数。结论颞骨CT三维重建可以明确地显示其内部各解剖结构及其相互间的空间立体关系。     

Inner ear dysplasia is common in children with Down syndrome (trisomy 21)

OBJECTIVES/HYPOTHESIS: Middle and external ear anomalies are well recognized in Down syndrome (DS, trisomy 21). Inner ear anomalies are much less frequently described. This study reviews inner ear morphology on imaging to determine the prevalence of cochlear and vestibular anomalies in children with DS. STUDY DESIGN: The authors conducted a retrospective review of imaging features of (DS) inner ear structures. METHODS: Fifty-nine sequential patients with DS with imaging of the inner ear were identified by a radiology report text search program. Quantitative biometric assessment of the inner ear was performed on patients with high-resolution computed tomography or magnetic resonance images of the petrous bone. Petrous imaging was performed for evaluation of inflammatory disease or hearing loss. Spinal imaging, which included petrous views, was performed in most cases to exclude C1 to 2 dislocation, a potential complication of DS. Measurements were compared with normative data. RESULTS: Inner ear dysplasia is much more common in DS than previously reported. Inner ear structures are universally hypoplastic. Vestibular malformations are particularly common and a small bony island of the lateral semicircular canal (<3 mm in diameter) appears highly typical. Additional findings in some patients were persistent lateral semicircular anlage with fusion of the lateral semicircular canal and vestibule into a single cavity, vestibular aqueduct and endolymphatic sac fossa enlargement, cochlear nerve canal hypoplasia, and stenosis or duplication of the internal auditory canal. Stenosis of the external meatus, poor mastoid pneumatization, middle ear and mastoid opacification, and cholesteatoma were common, as expected.     

Computed tomography of the temporal bone in diagnosis of chronic exudative otitis media

Computed tomography (CT) of the temporal bone was made in 37 patients aged 2 to 55 years with chronic exudative otitis media (CEOM). In 21 of them the pathology was bilateral. The analysis of 58 CT images has identified CT signs of chronic exudative otitis media. They include partial (17 temporary bones) or complete (38 temporal bones) block of the bone opening of the auditory tube, pneumatic defects of the tympanic cavity (58 temporal bones), pneumatic defects of the mastoid process and antrum (47 temporal bones), pathologic retraction of the tympanic membrane. The examination of the temporal bone detected both CT-signs of CEOM and other causes of hearing disorders in 14 patients (26 temporal bones) with CEOM symptoms and inadequately high hypoacusis. Among these causes were malformation of the auditory ossicula (n=5), malformation of the labynthine window (n=2), malformation of the middle and internal ear (n=4), a wide aqueduct of the vestibule, labyrinthine anomaly of Mondini's type (n=1), cochlear hypoplasia (n=4), stenosis of the internal acoustic meatuses (n=2). Sclerotic fibrous dysplasia was suggested in 2 temporal bones (by CT data). CT was repeated after surgical treatment of 10 patients (14 temporal bones) and visual assessment of tympanostomy results was made.     

Cytomegalovirus-induced pathology in human temporal bones with congenital and acquired infection

ObjectivePublications on histopathology of human temporal bones with cytomegalovirus (CMV) infection are limited. We aim to determine histopathology of the inner ears and the middle ears in human temporal bones with congenital and acquired CMV infections.MethodsTemporal bones from 2 infants with congenital and 2 adults with acquired CMV infection were evaluated by light microscopy.ResultsTwo infants with congenital CMV infection showed striking pathological changes in the inner ear. There was a hypervascularization of the stria vascularis in the cochlea of the first infant, but no obvious loss of outer and inner hair cells was seen in the organ of Corti. However, cytomegalic cells and a loss of outer hair cells were found in the cochlea of the second infant. The vestibular organs of both infants showed cytomegalic cells, mostly located on dark cells. There was a loss of type I and type II hair cells in the macula of the saccule and utricle. Loss of hair cells and degeneration of nerve fibers was also seen in the semicircular canals. Both infants with congenital infection showed abundant inflammatory cells and fibrous structures in the middle ear cavity. No evidence of cytomegalic cells and hair cell loss was found in the cochlea or vestibular labyrinth in acquired CMV infection.ConclusionsIn two infants with congenital CMV infection, the cochlea, vestibule, and middle ear were highly affected. Temporal bones of adult donors with acquired viral infection showed histological findings similar to donors of the same age without ear disease.     

Radiographic examination of patients with dehiscence of semicircular canals with digital volume tomography

Digital volume tomography (DVT) is an extension of panoramic tomography. With this diagnostic technique, characterized by high resolution, a narrow section width (0.125 mm), and three-dimensional display, small pathological processes can be well visualized. We examined 434 patients with DVT (Accu-I-tomo, Morita, Japan). Eleven patients with a history of peripheral vertigo presented a fistula of the labyrinth. The results were compared with intraoperative findings to evaluate the diagnostic value of DVT in cases of erosion of the semicircular canals. With high resolution and artifact-free demonstration of the labyrinth and inner ear structures, it was possible to determine the presence of a fistula of the semicircular canals in all 11 patients. An erosion of the lateral semicircular canal was found in nine patients with additional fistulae of the superior and posterior semicircular canals in one patient, a dehiscence of bone of the superior semicircular canal in one patient, and a dehiscence of the posterior semicircular canal in another patient. The predicted erosion of semicircular canals was verified in all patients during surgery where a closure of the fistulae was performed. DVT is an excellent technique to examine the semicircular canal structures in patients with peripheral vertigo, and expand the application of diagnostic possibilities in the lateral skull base. With this method, the preoperative diagnosis is improved allowing more accurate planning of the surgical procedure. DVT delivers a small radiation dose with a high resolution and a low purchase price for the equipment.