Patients with dysplasia of the auricle and external ear abnormalities: Evaluation of the temporal bones malformation with thin-section computed tomography

Purpose

To correlate the relationship of the degree of external, middle, and inner ears abnormalities and the degree of dysplasia of the auricle (microtia).

Methods

We used high-resolution CT, with axial and coronal 1-mm contiguous sections to examine the temporal bones of patients with microtia.

Results

In cases of type II and III microtia, bony atresia of the external auditory canal was predominant. The degrees of middle ear malformations and ossicular dysplasia were correlated with the severity of the auricular anomalies. Inner ear changes were uncommon.

Conclusion

Microtia is commonly associated with a variety of external, middle, and, less frequently inner ear abnormalities. High-resolution multiplanar CT scanning is the primary imaging modality of choice in the preoperative evaluation of patients with microtia and external auditory canal dysplasia.     

先天性外中耳畸形合并内耳畸形的HRCT表现

目的:总结先天性外中耳畸形合并内耳畸形的高分辨CT(HRCT)表现。方法:6例6耳先天性外中耳畸形同时合并内耳畸形,5例行横断面及冠状面HRCT扫描,1例仅行横断面扫描。分析先天性外中耳畸形合并内耳畸形的HRCT表现特点。结果:6耳不同程度的外中耳畸形合并的内耳畸形有:①外半规管畸形(6耳):外半规管短小或短粗;②前庭扩大(3耳):前庭增宽,左右径大于4mm;③前庭窗封闭(3耳):HRCT冠状面显示前庭窗结构消失;④内听道异常(2耳):内听道狭窄,可合并走行异常;⑤前庭导水管扩大(1耳):前庭导水管呈三角形扩大并与总脚相通。结论:部分先天性外中耳畸形可同时合并内耳畸形,HRCT检查时应重视发现这种复杂畸形。     

Computed tomography and magnetic resonance imaging of congenital abnormalities of the temporal bone

Congenital abnormalities of the temporal bone are mostly accompanied by conductive or sensori-neural hearing loss. Before any therapeutic procedures are done high resolution CT (HRCT) and magnetic resonance imaging (MRI) should be performed to establish the correct diagnosis and to plan the potentially surgical intervention. HRCT best depicts osseous changes especially those of the external auditory canal and the middle ear containing the ossicles and the osseous structures of the temporal bone and the petrous bone containing the inner ear. MRI excellently shows soft tissue changes of the inner ear especially on the high resolution 3DT2-weighted sequences which give a superb contrast between the nerves and the cerebro-spinal fluid. Malformations of the external auditory canal consists of aplasia or hypoplasia and those of the middle ear range form extreme hypoplasia or aplasia to very mild deformations of the ossicles. Malformations of the inner ear also range form complete aplasia to very mild hypoplasia of the organs of the inner ear as well as malformations concerning the nerves in the internal auditory canal range from aplasia to hypoplasia. Malformations of the temporal bone can either occur isolated or in combination in which malformations of the external and middle ear may be accompanied by those of the inner ear. Furthermore, malformations of the temporal bone may also occur in otofacial, otocervical or otoskeletal syndromes. These syndromes may be accompanied by certain malformations of the temporal bone. HRCT and MRI are both excellent methods to depict congenital abnormalities of the temporal bone and of the inner ear and should be used as complementary methods because HRCT best depicts osseous changes and MRI superbly depicts soft tissue changes. Both methods are important to establish the correct diagnosis to plan the therapeutic procedures.     

CT Findings in the External Auditory Canal after Transcanal Surgery

BACKGROUND AND PURPOSE:Middle ear surgery is often performed through the external auditory canal, and the CT appearance of the external auditory canal after transcanal middle ear surgery can mimic erosive pathology such as carcinoma, external auditory canal cholesteatoma, or necrotizing external otitis. We reviewed the CT findings in a group of patients following transcanal surgery to highlight this potential pitfall in interpretation.MATERIALS AND METHODS:Twenty-seven temporal bones in 25 patients with a history of a transcanal approach to the middle ear and available postoperative CT imaging were identified. Images were assessed for changes along or involving the walls of the external auditory canal, including widening, irregularity, bony defects, and soft tissue opacification.RESULTS:Osseous changes along the floor of the external auditory canal were demonstrated in 25 of 27 (92.6%) temporal bone CT scans. Similar changes were present in the superior and anterior walls of the external auditory canal in 21 and 18 temporal bones, respectively. The anterior wall was the most common site for complete bony defects (10 of 27 temporal bones). The posterior wall was the least often involved, with osseous changes in 15 of 27 temporal bones and bony defects in 3 cases. Soft tissue thickening was seen most commonly along the floor. No patient was found to have a superimposed pathologic process of the external auditory canal.CONCLUSIONS:CT findings in the external auditory canal after transcanal surgery include thinning, irregularity and/or flattening of the bone, soft tissue thickening, and bony wall defects. Although these changes may be subtle, they may mimic pathology and should be included in the differential diagnosis of osseous abnormality of the external auditory canal.

Middle ear surgery performed through the external auditory canal (EAC) often involves drilling a portion of the bony canal wall to provide access and necessary exposure.^1–3 In the absence of associated transmastoid surgery (such as a canal wall down mastoidectomy), the postoperative status may not be immediately obvious to the interpreting radiologist, and relevant history may not be provided. On CT, such postoperative changes in the external canal can mimic bony and soft tissue changes typically associated with neoplasms, external canal cholesteatoma, or aggressive infections of the EAC. Prior literature has predominantly focused on the appearance of the middle ear after surgery.^4–11 We describe the CT appearance of the EAC after transcanal surgery so that postoperative change can be included in the differential diagnosis, even in the absence of available history, and erroneous diagnoses may be avoided.     

333例先天性外中耳畸形的CT分析

目的：分析先天性外中耳畸形的各种ＣＴ特征。材料与方法：对高分辨率ＣＴ确诊为外中耳畸形的３３３例４０４耳的病变部位和类型进行分析。结果：４０４耳中３６４耳外耳道闭锁，４０耳外耳道狭窄，３７７耳有听小骨畸形，３８２耳鼓室狭窄，３３３耳面神经管乳突段前位。结论：颞骨高分辨ＣＴ可获得外、中、内耳畸形类型的影像资料，可为临床制定治疗方案提供依据。     

Computer tomography in children and adolescents with suspected malformation of the petrous portion of the temporal bone

Purpose: To demonstrate HRCT findings and their therapeutic relevance in suspected congenital hearing disorders. Material and Methods: It was checked in 96 young patients if HRCT findings of the temporal bone could explain functional findings. Furthermore, the therapeutic consequences were noted. Results: Normal CT and normal functional findings were obtained in 49 temporal bones (TB). In conductive hearing loss (41 TB), dysplasias of the conducting apparatus (37 TB) and inflammatory changes (3 TB) were found. Combined hearing loss (18 TB) was clarified completely or partially in half the cases. There were 22 dysplasias of the inner ear, 3 dysplasias of the middle ear, 1 abandoned examination (2 TB), and 55 normal CT findings in senorineural hearing disorders (82 TB). 1 retardate had a malformation of the inner ear and, contralaterally, inflammatory middle ear. In cases of vestibular disorders (24 TB), 14 malformations of the inner ear were detected. An indication for an operation was given in 23 TB. In 22 TB, it was contraindicated. The CT was one preliminary examination to a cochlea implant in 19 patients. The therapy was carried on with hearing devices in the other patients. Conclusion: HRCT is an important method in diagnosis and therapeutic planning of suspected malformations of the temporal bone.      

Congenital Aural Atresia: What the Radiologist Needs to Know?

Congenital aural atresia (CAA) is characterized by hypoplasia or aplasia of external auditory canal associated with auricular deformity. It also embodies a spectrum of temporal bone abnormalities including anomalies of middle ear, ossicles, facial nerve, oval window, round window, mastoid pneumatization, temporomandibular joint and occasionally inner ear and vascular anomalies. The management in such patients is variable and consists of rehabilitative hearing aids or surgical correction depending on various patient factors like associated temporal bone abnormalities, degree of hearing impairment and laterality. Surgical management if planned, depends on the extent of associated temporal bone anomalies and hence necessitates comprehensive knowledge about the normal and abnormal anatomy of these structures. High resolution computed tomography (HRCT) is the optimal investigation which provides required anatomical information and plays a pivotal role in deciding the management strategy. This pictorial review aims to review the spectrum of anomalies involving critical structures in CAA on HRCT along with their clinical significance.     

Congenital malformations of the inner ear and the vestibulocochlear nerve in children with sensorineural hearing loss: evaluation with CT and MRI

PURPOSE: The purpose of this work was to study the diagnostic value of CT and MRI in children with sensorineural hearing loss and to analyze anatomic abnormalities of the inner ear and the vestibulocochlear nerve in this patient group. METHOD: We evaluated 42 inner ears in 21 children with congenital deafness who had congenital inner ear malformations and who were candidates for cochlear implants. All patients were studied with high resolution MR and helical CT examinations. The MR study included a T2-weighted 3D fast SE sequence. We describe and tabulate the anatomic abnormalities. Special attention was given to abnormalities of the vestibulocochlear nerve. The field of view in the plane according to the length axis of the internal auditory canal (IAC) was 4 cm. Additional continuous parasagittal reformations perpendicular to the length axis of the IAC were studied with a field of view of 3 cm. RESULTS: CT and MRI allowed accurate identification of malformations of the inner ear in children with congenital deafness. We identified 99 malformations, with a majority of patients demonstrating multiple abnormalities. Common imaging findings were Mondini abnormality and Mondini variants (12/42) and fusion of the lateral or superior semicircular canal with the vestibule (12/42). MRI demonstrated in 9 of 21 patients a rudimentary or absent vestibulocochlear nerve in the auditory canal. CONCLUSION: CT and MRI are important modalities to analyze the inner ear in children who are candidates for cochlear implants. MRI with an extremely small field of view should be used to study possible abnormalities of the vestibulocochlear nerves. This may alter clinical care and allow cochlear implant placement in patients whose electrodiagnostic studies suggest that the implant should not be performed. The detailed analysis of abnormalities of the inner ear might establish prognostic factors.     

Computed tomography and magnetic resonance tomography of the normal temporal bone

The normal anatomy of the temporal bone and the inner ear will be described in detail on high resolution computed tomography (HRCT) and magnetic resonance images. The imaging technique of computer tomography--either single detector or multi detector CT--is normally obtained in an axial plane without the intravenous application of contrast material. The images are reconstructed in a high resolution bone window level setting. The coronal images are reconstructed either if used single detector or multi detector CT. Only in some cases a scan in the coronal plane is directly obtained using a single detector CT. MR imaging of temporal bone is usually performed in a head coil. Axial high resolution 3D-T2-weighted sequences either in fast spin echo technique or gradient echo technique--for example CISS-sequence--are obtained, then an axial high resolution T1-weighted sequence before and after the application of gadopentate dimiglumine is performed. HRCT excellently demonstrates the osseous structures of the temporal bone as well as of the inner ear, while MRI excellently depicts soft tissue structures especially those of the inner ear. Due to the susceptibility artifacts MRI is not very suitable for imaging the external auditory canal or the middle ear or the pneumatic system. In conclusion HRCT is so far excellent to delineate the osseous structures of the temporal bone and inner ear while MRI excellently depicts the soft tissue structures of the inner ear, the internal auditory canal and the cerebellopontine angle. Reissner's membrane, the cochlear duct, and the organ of Corti cannot be visualized even using high-resolution MRI. HRCT and MRI are therefore used as complementary methods for imaging the temporal bone.     

外中耳先天畸形的HRCT研究

目的 研究外中耳先天畸形的高分辨CT（HRCT）表现,为临床诊断和治疗提供准确信息。资料与方法 对临床诊断的外、中耳先天畸形35例行HRCT扫描,单纯横断位扫描5例,横断位加冠状位扫描30例。结果 （1）外耳畸形32例共42耳,其中外耳道骨性闭锁30耳,显示闭锁板为完全性26耳,不完全性4耳。膜性闭锁5耳。双侧分别为不同类型闭锁1例。外耳道狭窄7耳,其中狭窄合并对侧闭锁1例。合并畸形中,面神经管垂直段明显前移22耳,下颌髁状突明显后上移25耳,乙状窦前移4耳,均见于骨性外耳道闭锁。伴发的中耳畸形主要为小鼓室及不同程度的听骨发育不全或缺如。合并内耳发育不全1例。（2）单纯性中耳畸形3例共6耳,均表现为听小骨异常。合并小鼓室1例,耳咽管和鼓室窦畸形扩大1例。结论 HRCT能准确显示外中耳先天畸形的类型、程度以及合并畸形,为临床治疗方案的正确制定提供重要的参考依据。     

320排640层CT在耳部畸形诊断中的临床应用价值探讨

目的:探讨320排640层动态容积CT在耳部畸形诊断上的临床应用价值。方法:收集2011-01～2012-01间行320排640层动态容积CT耳部检查先天性耳部病变患者31例共44耳,使用Toshiba Aquilion One动态容积CT机,采用160×0.5容积扫描模式。采集到的数据,常规进行1.0 mm横断面重建,高分辨率算法(sharp verysharp或bone)。结果:外耳道闭锁16例18耳,同时16例中伴有鼓室形态异常4耳,听小骨形态异常3耳,鼓室并听小骨形态异常1耳,患耳侧乳突呈板障型者2耳。外耳道狭窄4例5耳。内耳形态异常或畸形10例19耳。结论:320排640层动态容积CT先进的软硬件技术,评价内耳畸形可靠性进一步提升。     

The Lacrimo-Auriculo-Dento-Digital (LADD) syndrome: temporal bone CT findings.

The temporal bone CT examination of a 16-year-old female patient with the LADD syndrome or Levy-Hollister syndrome showed multiple bilateral middle as well as inner ear malformations. Ossicular chain anomalies were seen, especially of the incus and stapes. The oval window was very narrow to absent. Both cochleas were hypoplastic and showed modiolar deficiency. A common cavity between the vestibule and lateral semicircular canal was bilaterally present.     

Congenital sensorineural hearing loss

The ears of 47 selected patients with congenital sensorineural hearing loss were examined with complex-motion tomography. The patients were divided into 3 general categories: those with a recognized syndrome, those with sensorineural hearing loss unrelated to any known syndrome, and those with microtia. A great variety of inner ear anomalies was detected, but rarely were these characteristic of a particular clinical entity. The most common finding was the Mondini malformation or one of its variants. Isolated dysplasia of the internal auditory canal or the vestibular aqueduct may be responsible for sensorineural hearing loss in some patients. Patients with microtia may also have severe inner ear abnormalities despite the fact that the outer and inner ears develop embryologically from completely separate systems.     

High resolution CT findings in diseases of the external auditory canal. A review of 31 cases

Thirty-one patients with pathology of the external auditory canal (EAC) were examined with high resolution CT. In this retrospective study we found that CT plays an important role in the diagnosis and especially in the determination of the extent of the disease. CT also offered us a good evaluation of the contiguous bone and it was the best method to visualize the middle ear when complete occlusion of the external auditory canal (EAC) occurred.     

Complicated cholesteatomas: CT findings in inner ear complications of middle ear cholesteatomas

Patients with facial palsy and middle ear disease, which may be chronic but clinically occult, may have a cholesteatoma with extension medially along the facial canal. In two patients, axial computed tomographic (CT) scans demonstrated involvement of the medial petrous bone. Patients with vertigo and chronic middle ear disease may have a cholesteatoma with a "fistula" between the middle and inner ears. Although the fistula usually involves the lateral semicircular canal, the cholesteatoma may pass through the oval window. In two patients, coronal CT scans showed extension to the oval window in one and through it in the other.     

Imaging findings of the developing temporal bone in fetal specimens.

PURPOSETo trace the development of the normal fetal temporal bone by means of plain radiography, MR, and CT.METHODSEighteen formalin-fixed fetal specimens, 13.5 to 24.4 weeks'' gestational age, were examined with a mammographic plain film technique, CT, and MR imaging at 1.5 T. Temporal bone development and ossification were assessed.RESULTSThe membranous labyrinth grows with amazing rapidity and attains adult size by the middle of the gestation period. The cochlea, vestibule, and semicircular canals are very prominent and easily recognized on MR images. The otic capsule develops from a cartilage model. Ossification of the otic capsule proceeds rapidly between 18 and 24 weeks from multiple ossification centers that replace the cartilaginous framework. The mastoid, internal auditory canal, vestibular aqueduct, and external auditory canal continue to grow after birth.CONCLUSIONThe study of fetal developmental anatomy may lead to a better understanding of congenital disorders of the ear. Faster MR scanning techniques may provide a method for in utero evaluation of the fetal temporal bone.     

侵及颈静脉孔区的原发性中耳癌的CT、MRI诊断

目的 探讨侵及颈静脉孔区的原发性中耳癌的CT、MRI特点.方法 回顾性分析7例经手术病理证实的侵及颈静脉孔区原发性中耳癌患者的CT、MRI资料,其中6例行高分辨率CT(HRCT)扫描,1例行常规CT增强扫描,7例均行MR平扫+增强.结果 HRCT显示鼓室、鼓窦、外耳道深部及颈静脉孔区软组织病灶伴不规则虫蚀样骨质破坏,涉及颈静脉孔(7例)、咽鼓管骨性段(7例)、面神经管(4例)、颈动脉管(4例)、外耳道前后壁(3例)、听小骨(2例)及前庭窗、水平半规管(1例)等结构的破坏.4例病变密度较均匀,CT值约30～55 HU,2例肿块内见少许小片状高密度影.1例CT增强显示中度较均匀强化.MR平扫示边界不清软组织肿块,与脑灰质相比,T1WI呈等、略低信号,T2WI呈等、略高信号,其中5例信号较均匀,2例肿块内见少许小片状T1WI、T2WI低信号灶,增强扫描5例呈中度较均匀强化,2例不均匀强化,内见小片状无强化区.MRI显示4例侵及颈内动脉,1例侵及乙状窦.结论 原发性中耳癌可广泛侵及颈静脉孔区,易造成误诊.HRCT可准确显示中耳癌骨质破坏特点及范围,咽鼓管骨性段破坏可帮助减少误诊;MRI能更清楚显示病变范围,肿瘤信号及强化方式有一定特点.     

CT and MR of temporal bone malignancies primary and secondary to parotid carcinoma.

PURPOSETo review the CT and MR characteristics of temporal bone malignancy, and to evaluate the relationship between malignancies of the temporal bone and parotid gland.METHODSA group of 15 surgical patients with diagnosis of temporal bone malignancy were retrospectively reviewed. These included 11 cases of primary temporal bone malignancy and four cases of secondary carcinoma of the temporal bone from a primary tumor of the parotid gland. Three primary temporal bone malignancies were recurrences, and two secondary tumors were parotid recurrences.RESULTSFive of the 11 patients with primary temporal bone malignancy had parotid infiltration (45%). All four patients with secondary temporal bone destruction caused by parotid carcinoma had erosion of the mastoid, two with erosion of the external auditory canal, and one of the middle ear.CONCLUSIONSIt is important radiographically to recognize the close relationship between malignancies of the temporal bone and parotid gland, because either may secondarily invade the other. Suspicion of malignancy in either the temporal bone or parotid gland necessitates complete imaging of the other structure. Temporal bone or skull base erosion were best seen on CT at bone algorithm. MR with and without infusion provided excellent delineation of soft-tissue tumor margins, muscle infiltration, intracranial extension, and vascular encasement.     

Detection of acoustic schwannoma: use of constructive interference in the steady state three-dimensional MR.

PURPOSETo compare constructive interference in the steady state (CISS) three-dimensional Fourier transform (3DFT) MR imaging with contrast-enhanced T1-weighted spin-echo MR imaging for accuracy in detecting acoustic schwannoma.METHODSOne hundred twenty-five consecutive patients with possible acoustic schwannoma were examined. The accuracy of CISS-3DFT MR imaging in detecting abnormalities of the cerebellopontine angle, the internal auditory canal, and the inner ear was compared with T1-weighted contrast-enhanced spin-echo MR imaging by independent assessment of both image sets by two observers.RESULTSThe postcontrast T1-weighted MR images revealed 18 cases of unilateral disease of the cerebellopontine angle and/or the internal auditory canal and no case of an abnormal bilateral cerebellopontine angle and/or internal auditory canal. Twelve cases were pathologically proved acoustic schwannomas. One meningioma of the cerebellopontine angle and one metastatic ependymoma to the cerebellopontine angle and the internal auditory canal was encountered. The four remaining cases had a provisional diagnosis of acoustic schwannoma and were scheduled for follow-up imaging and clinical review. Analysis of whether contrast material would have been administered to the appropriate patients (ie, those with disease of the cerebellopontine angle and/or internal auditory canal) according to CISS MR imaging findings revealed a sensitivity of 100% and a specificity of 98% for observer 1 and a sensitivity of 94% and a specificity of 94% for observer 2.CONCLUSIONCISS-3DFT MR imaging, in this patient population, provided high sensitivity and specificity in detecting lesions of the cerebellopontine angle and internal auditory canal; however, further experience is required before a definitive statement regarding the suitability of this technique as a screening procedure can be made. When contrast material cannot be administered, CISS MR imaging may be considered an adequate examination for the evaluation of possible acoustic schwannoma.     

Three-dimensional MR of the inner ear with steady-state free precession.

PURPOSETo describe the steady-state free-precession MR sequence and its application to the study of the inner ear.METHODThe inner ear was imaged with CT and a 0.5-T MR unit in three dimension, to evaluate the various signals from the lumen of the labyrinth.RESULTSNormally, the signal from the perilymphatic and endolymphatic spaces is homogeneous. However, among our cases of neurosensory deafness, differences of signal and morphology were seen in patients with otosclerosis, ossifying labyrinthitis, and inner ear malformations.CONCLUSIONThree-dimensional MR, used together with routine two-dimensional fast spin-echo, is another diagnostic too]l that can provide new data in the evaluation of the normal and unhealthy inner ear.