Virtual reality modelling language: freely available cross-platform visualization technique for 3-D visualization of the inner ear

This was a study of the use of virtual reality modelling language (VRML) for cross-platform interactive three-dimensional (3-D) visualization of high-resolution magnetic resonance (MR) images of the inner ear in the assessment of cochlear implant candidates. A retrospective case review was made of cochlear implant candidates undergoing pre-operative high-resolution MR studies to determine their suitability for implantation. 3-D visualizations of MR scans of the inner ear structures were created using surface rendering and exported as portable VRML files. Case studies are presented to illustrate different points of interest. VRML reconstructions aided the interpretation of two-dimensional (2-D) source images in a variety of inner ear abnormalities. VRML is an internationally recognized standard for cross-platform 3-D visualization that creates a means of providing the implanting surgeon with a portable 3-D representation of the inner ear, aiding interpretation of the complex cross-sectional anatomy of these structures, and guiding selection of patients for implantation as well as implantation technique. The elucidation of the mechanisms behind inner ear malformations can also be aided by detailed imaging studies of the temporal bone, with VRML reconstructions providing an easily interpreted representation of deformities.     

Vestibulo-ocular reflex (VOR) preserved in bilateral severe vestibular malformations with internal auditory canal stenosis

A 60-year-old woman, who has suffered from bilateral deafness throughout her life, visited our outpatient clinic. Computed tomography (CT) revealed inner ear malformations, which comprise cochlear aplasia with hypoplastic vestibule in the right ear and a common cavity in the left ear, and narrow internal auditory canals. We performed electronystagmography with caloric stimulation and stimulation of earth-vertical axis rotation (EVAR) or off-vertical axis rotation (OVAR), and studied vestibular evoked myogenic potentials (VEMPs) and vestibular ocular reflex (VOR). Slight horizontal nystagmus was induced by the stimulation of EVAR but not by caloric stimulation. Slight vertical nystagmus was observed during OVAR, whereas the VEMP test elicited no response. The result of horizontal or vertical VOR performed in the dark was almost normal. These findings suggest that VOR can be acquired even with severe malformation of the inner ear whose labyrinthine functions markedly reduce bilaterally until nystagmus is slightly induced by rotation stimulation.     

高分辨率CT容积重建对内耳畸形的诊断价值

目的：通过高分辨率CT（HRCT）容积重建（VR）对正常内耳形态的观察,探讨其对先天性内耳畸形的诊断价值。方法：对10例（20耳）无耳部疾患者（对照组）和7例（11耳）先天性内耳畸形患者（病变组）行HRCT扫描,利用容积漫游技术对内耳骨迷路重建。对照组观察内耳骨迷路的正常结构,病变组观察内耳畸形情况。结果：正常耳VR图像不但显示了内耳骨迷路的细微结构,而且还反映了各结构之间的关系;病变耳立体显示了畸形部位及程度。11耳患耳中Mondini型7耳次;前庭及半规管畸形3耳次;前庭导水管扩大7耳次,其中6耳次伴随其他畸形;内耳道畸形2耳次且均伴随其他畸形。11耳畸形中9耳HRCT横断面图像和平面重建（MPR）冠状位图像、VR图像均可以清晰地显示畸形的部位和程度,其中VR图像可以直观、立体地显示畸形的空间形态结构;2耳水平半规管短小畸形患者VR图像较断面图像更好地显示了畸形的部位和程度。结论：VR三维重建可以立体显示正常内耳骨迷路的形态,直观显示内耳畸形的程度及病变位置,对内耳畸形的诊断具有重要的辅助价值。     

Vestibulo-ocular reflex (VOR) preserved in bilateral severe vestibular malformations with internal auditory canal stenosis

A 60-year-old woman, who has suffered from bilateral deafness throughout her life, visited our outpatient clinic. Computed tomography (CT) revealed inner ear malformations, which comprise cochlear aplasia with hypoplastic vestibule in the right ear and a common cavity in the left ear, and narrow internal auditory canals. We performed electronystagmography with caloric stimulation and stimulation of earth-vertical axis rotation (EVAR) or off-vertical axis rotation (OVAR), and studied vestibular evoked myogenic potentials (VEMPs) and vestibular ocular reflex (VOR). Slight horizontal nystagmus was induced by the stimulation of EVAR but not by caloric stimulation. Slight vertical nystagmus was observed during OVAR, whereas the VEMP test elicited no response. The result of horizontal or vertical VOR performed in the dark was almost normal. These findings suggest that VOR can be acquired even with severe malformation of the inner ear whose labyrinthine functions markedly reduce bilaterally until nystagmus is slightly induced by rotation stimulation.     

Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging investigation of inner ear disturbances in cases of middle ear cholesteatoma with labyrinthine fistula.

OBJECTIVE: To investigate the cause of inner ear disturbances in cases of middle ear cholesteatoma with labyrinthine fistula. SETTING: University hospital. STUDY DESIGN: Prospective case study. PATIENTS: Eight patients who were scheduled to undergo surgery for middle ear cholesteatoma with labyrinthine fistula were included in this study. INTERVENTION: Imaging analysis was performed using a 3-dimensional fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging sequence. MAIN OUTCOME MEASURES: Three-dimensional FLAIR findings were compared with clinical symptoms associated with inner ear disturbance and surgical observations of the fistula. RESULTS: Three-dimensional FLAIR in 6 patients revealed areas of high signal intensity in the inner ears on the affected sides and areas with increased signal after the administration of gadolinium, especially in cases accompanied by acute sensorineural hearing loss. These images were considered to be indicative of breakdown of the blood-labyrinth barrier due to middle ear cholesteatoma. This finding was also present in a patient with no clinical symptoms of inner ear disturbances. CONCLUSION: Three-dimensional FLAIR images of the inner ear are valuable in evaluating labyrinthine fistula in patients with cholesteatoma. Future studies are needed to better understand the role of 3-dimensional FLAIR in predicting the severity of inner ear disturbance.     

N-acetylcysteine as a single therapy for sudden deafness

Conclusion: Like NAC ameliorates hearing loss from acoustic trauma in the inner ear, NAC may also rescue hearing loss from sudden deafness confined to the inner ear.

Objective: This study assesses the effect of N-acetyl-L-cysteine (NAC) as a single therapy for sudden deafness.

Methods: Thirty-five sudden deafness patients with neither systemic disorders nor central signs in electronystagmography were treated with NAC alone and assigned to Group A. For comparison, another 35 sudden deafness patients treated by corticosteroids and plasma expander were assigned to Group B. There were no significant differences between the two groups in terms of age, sex, laterality, and pre-treatment mean hearing level. All patients underwent an inner ear test battery comprising audiometry, and ocular vestibular-evoked myogenic potential (oVEMP), cervical VEMP (cVEMP), and caloric tests.

Results: Groups A and B did not significantly differ in the pre-treatment mean hearing level, and percentages of abnormal oVEMP, cVEMP, and caloric tests, indicating that the involvement severity of sudden deafness between the two groups was similar. However, Group A (43?±?27?dB) showed significantly greater mean hearing gain than Group B (21?±?28?dB), and Group A (91%) revealed better improved rate of hearing than Group B (57%).     

A Post-processing Protocol for Three-dimensional Visualization of the Inner Ear Using the Volume-rendering Technique Based on a Standard Magnetic Resonance Imaging Protocol

A superior diagnostic quality compared to other post-processing (PP) techniques for three-dimensional (3D) inner ear imaging has been attributed to volume rendering (VR). We defined and assessed a VR protocol for 3D visualization of the inner ear in a routine imaging setting. Following definition of a VR protocol by using lower threshold values, surface shading, perspective views and related parameters, standardized 3D views of the inner ear were generated and evaluated in 32 patients suffering from sensorineural or combined hearing loss. Comprehensive inner ear visualization was achieved in 28 patients by means of two 3D shaded-surface views. Incomplete data acquisition (1/32), motion and pulsation artefacts (2/32) and interposed fluid-retaining mastoid cells (1/32) were responsible for non-diagnostic image quality in 4/32 patients. In 5/32 patients modifications of the PP protocol involving the threshold value and depth-cueing parameters helped to establish diagnostic image quality. Mean post-processing time amounted to 5.8 min per site. 3D imaging with the VR technique is suitable for routine inner ear assessment if direct VR, predefined PP protocols and standardized labyrinthine views are used.     

A post-processing protocol for three-dimensional visualization of the inner ear using the volume-rendering technique based on a standard magnetic resonance imaging protocol.

A superior diagnostic quality compared to other post-processing (PP) techniques for three-dimensional (3D) inner ear imaging has been attributed to volume rendering (VR). We defined and assessed a VR protocol for 3D visualization of the inner ear in a routine imaging setting. Following definition of a VR protocol by using lower threshold values, surface shading, perspective views and related parameters, standardized 3D views of the inner ear were generated and evaluated in 32 patients suffering from sensorineural or combined hearing loss. Comprehensive inner ear visualization was achieved in 28 patients by means of two 3D shaded-surface views. Incomplete data acquisition (1/32), motion and pulsation artefacts (2/32) and interposed fluid-retaining mastoid cells (1/32) were responsible for non-diagnostic image quality in 4/32 patients. In 5/32 patients modifications of the PP protocol involving the threshold value and depth-cueing parameters helped to establish diagnostic image quality. Mean post-processing time amounted to 5.8 min per site. 3D imaging with the VR technique is suitable for routine inner ear assessment if direct VR, predefined PP protocols and standardized labyrinthine views are used.     

Assessment of the caloric-induced tilt in the perceived visual vertical: preliminary report

OBJECTIVE: The perceived visual vertical (PVV) has been shown to be abnormal in patients with acute vestibular lesions but reverts to normal in compensated patients. The objectives of this study are to ascertain whether the PVV can be modulated by caloric stimulation and whether this modulation diminishes in compensated patients with unilateral vestibular lesions. DESIGN: Prospective. SETTING: Tertiary care facility. METHOD: Sixty-eight patients referred for vestibular testing had an electronystagmography and a PVV. MAIN OUTCOME MEASURES: Tilt in PVV, in degrees after caloric stimulation. RESULTS: Cold caloric stimulation resulted in a mean tilt in the PVV toward the irrigated ear and warm irrigation had the reverse effect. The mean modulation (amplitude of the angular distance in degrees between cold and warm tilts) was 4.3 degrees. In a subgroup of patients with severe unilateral vestibular dysfunction, this modulation of the PVV with caloric stimulation was diminished on the side of the lesion (p = .0001). CONCLUSION: Further study is required to assess the potential of the caloric PVV as a test of otolith function.     

Inner ear decompression sickness and inner ear barotrauma in recreational divers: a long-term follow-up

OBJECTIVES/HYPOTHESIS: The objectives were to report the authors' experience with the long-term follow-up of patients with diving-related inner ear decompression sickness and inner ear barotrauma and to discuss residual cochlear and vestibular damage in relation to the question of fitness to dive. STUDY DESIGN: Retrospective consecutive case series. METHODS: Eleven recreational divers with inner ear decompression sickness and nine with inner ear barotrauma (IEB) were followed. A complete otoneurological physical examination and laboratory evaluation were carried out. The latter included audiometry, electronystagmography, a rotatory chair test using the sinusoidal harmonic acceleration protocol, and computerized dynamic posturography. RESULTS: Residual cochleovestibular deficits were found in 10 (91%) of the patients with inner ear decompression sickness and 3 (33%) of those with IEB (P <.02, Fisher's Exact test; odds ratio, 20). A significantly shorter follow-up period was required for the inner ear barotrauma group (P <.05, simple t test) because three patients (33%) recovered completely within 1 month of the diving accident. Eight patients had residual vestibular deficits on follow-up, but only one (12.5%) was symptomatic. However, five (56%) of the nine patients who had a cochlear insult, as documented by follow-up audiometry, complained of significant hearing loss and tinnitus. CONCLUSION: Inner ear decompression sickness carries a high risk for residual inner ear damage despite hyperbaric oxygen recompression therapy. A favorable prognosis might be anticipated for inner ear barotrauma. The finding that most patients with residual vestibular deficits were asymptomatic at the time of follow-up emphasizes the need for a complete vestibular evaluation, including specific bedside testing and laboratory examinations, before a return to diving activity may be considered.     

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.     

人工耳蜗植入术后植入电极的影像学检查

目的 探讨建立螺旋CT扫描及三维重建技术观察人工耳蜗植入电极方法，并比较X线摄片方法与螺旋CT扫描三维重建方法的耳蜗内电极的影像学特征及其临床应用价值。方法 18例人工耳蜗植入患者全部作术后X线摄片检查。其中9例用经眼眶前后位摄片，9例采用侧斜位60。摄片。3例患者施行术后螺旋CT扫描及内耳三维重建方法。结果 2种投射头位的X线摄片均可显示电极形态及单个电极对，可间接判断电极在耳蜗内的植入深度。螺旋CT扫描三维重建图可直观地显示耳蜗形态、电极形态及其在耳蜗内植入的深度，可清晰识别单个电极对。结论 螺旋CT扫描三维重建方法可直观观察植入电极的形态及位置，可准确判断电极在耳蜗内植入的深度，有其独特的临床应用价值。     

Immunosuppressive treatment in bilateral vestibulopathy with inner ear antibodies

CONCLUSIONS: Although vestibular recovery was observed after steroid treatment, it remains uncertain whether this improvement was spontaneous or due to medication. These data do not allow us to generally recommend corticosteroid treatment in patients with BVF and inner ear antibodies. OBJECTIVE: A retrospective study was performed based on the observation of two patients with suspected autoimmune bilateral vestibular failure (BVF) with normal hearing and antilabyrinthine or nervous tissue-specific serum antibodies who showed vestibular recovery after corticosteroid treatment. MATERIAL AND METHODS: Twelve patients with BVF and serum inner ear antibodies who had received imuunosuppressive treatment with corticosteroids were evaluated in terms of medical history, repetitive caloric irrigation and repetitive determination of inner ear antibodies. BVF was complete in four patients and incomplete in eight. RESULTS: After immunosuppressive therapy, four of the 12 patients showed a moderate recovery of the peak slow-phase velocity of horizontal nystagmus induced by bithermal caloric stimulation, which was only transient in two of them.     

Schnelle interaktive 3D-Darstellung des Felsenbeins mit “direktem Volume Rendering”

INTRODUCTION: For the first time, the relatively new method of interactive direct volume rendering (dVR) allows for a fast and direct three-dimensional visualization of spiral CT data without any manual, explicit segmentation. This study was performed to prove whether dVR is capable of providing a meaningful three-dimensional visualization of the structures within the temporal bone. PATIENTS AND METHODS: In ten patients a three-dimensional visualization of the structures of the inner and middle ear was performed from spiral CT data on a commercially available graphics workstation. RESULTS: The cochlea and semicircular canals were visualized in good quality in all patients. The ossicles and bony facial canal were visualized in good or fair quality in most cases. The time needed for the visualization of the data and all target structures was less than 15 min in all cases. CONCLUSIONS: Three-dimensional visualization of the structures within the temporal bone from high-resolution spiral CT data using dVR is easily performed in a very short time on standard graphics workstations. This allows integrating three-dimensional visualizations into routine clinical work.     

Clinical features of sudden hearing loss associated with a high signal in the labyrinth on unenhanced T1-weighted magnetic resonance imaging

We report on five patients with high signals in the labyrinth on unenhanced magnetic resonance imaging who developed sudden hearing loss and vertigo. Weissman et al. (1992) suggested the possibility that such high signals were caused by hemorrhage. We assessed these patients using audiograms, caloric tests, and auditory brainstem responses to investigate the possibility of inner ear hemorrhage. Most of the patients were found to have severe and irreversible impairment of both cochlear and vestibular function. These findings were consistent with the hypothesis that their symptoms were caused by inner ear hemorrhage. Received: 3 November 1999 / Accepted: 20 January 2000     

Inner ear anomalies are frequent but nonobligatory features of the branchio-oto-renal syndrome

OBJECTIVE: To summarize the syndromic features and evaluate the presence of inner ear anomalies in 35 patients with branchio-oto-renal (BOR) syndrome from 6 families. DESIGN: Retrospective evaluation of magnetic resonance imaging of the temporal bones and clinical features in patients with BOR syndrome. SETTING: Tertiary referral center. PATIENTS: The study population comprised 35 clinically affected patients with BOR syndrome from 6 families. Most of these families were followed for over 25 years. MAIN OUTCOME MEASURES: Twenty-four patients underwent high-resolution, heavily T2-weighted 3-dimensional magnetic resonance imaging of the temporal bones for evaluation of inner ear anomalies. Special attention was paid to the endolymphatic duct and sac. RESULTS: A total of 7 enlarged endolymphatic ducts and sacs (3 bilaterally and 4 unilaterally) and 5 enlarged endolymphatic ducts only (2 bilaterally and 3 unilaterally) were observed. Eight hypoplastic cochleas and 6 hypoplastic labyrinths were seen bilaterally. Seven family members had normal inner ears. CONCLUSION: These findings suggest that inner ear anomalies are frequent but nonobligatory features of BOR syndrome.     

Diagnostic value of vestibulo-ocular reflex parameters in the detection and characterization of labyrinthine lesions.

OBJECTIVE: To evaluate the power of various parameters of the vestibulo-ocular reflex (VOR) in detecting unilateral peripheral vestibular dysfunction and in characterizing certain inner ear pathologies. STUDY DESIGN: Prospective study of consecutive ambulatory patients presenting with acute onset of peripheral vertigo and spontaneous nystagmus. SETTING: Tertiary referral center. PATIENTS: Seventy-four patients (40 females, 34 males) and 22 normal subjects (11 females, 11 males) were included in the study. Patients were classified in three main diagnoses: vestibular neuritis: 40; viral labyrinthitis: 22; Meniere's disease: 12. METHODS: The VOR function was evaluated by standard caloric and impulse rotary tests (velocity step). A mathematical model of vestibular function was used to characterize the VOR response to rotational stimulation. The diagnostic value of the different VOR parameters was assessed by uni- and multivariable logistic regression. RESULTS: In univariable analysis, caloric asymmetry emerged as the most powerful VOR parameter in identifying unilateral vestibular deficit, with a boundary limit set at 20%. In multivariable analysis, the combination of caloric asymmetry and rotational time constant asymmetry significantly improved the discriminatory power over caloric alone (p<0.0001) and produced a detection score with a correct classification of 92.4%. In discriminating labyrinthine diseases, different combinations of the VOR parameters were obtained for each diagnosis (p<0.003) supporting that the VOR characteristics differ between the three inner ear disorders. However, the clinical usefulness of these characteristics in separating the pathologies was limited. CONCLUSION: We propose a powerful logistic model combining the indices of caloric and time constant asymmetries to detect a peripheral vestibular loss, with an accuracy of 92.4%. Based on vestibular data only, the discrimination between the different inner ear diseases is statistically possible, which supports different pathophysiologic changes in labyrinthine pathologies.     

同种内耳抗原免疫致聋豚鼠的子代内耳功能和形态学观察

目的观察自身免疫性感音神经性聋(autoimmune sensorineural hearing loss，ASHL)母鼠所产子代内耳听觉和前庭生理功能、病理形态学的变化，初步探讨母鼠体内针对内耳组织抗原免疫反应是否可以造成子代的内耳损伤。方法同种内耳抗原(homogeneous inner ear antigens，HIEAg)持续免疫孕豚鼠，采用耳蜗电图(包括听神经复合动作电位)、总和直流电位、耳蜗微音器电位和眼震电图仪(记录自发性和冷热空气试验)测试母鼠和子鼠的听觉和前庭功能，并检测针对HIEAg的血清特异性体液和细胞免疫反应，采用火棉胶切片和HE染色，光镜观察内耳病理组织学改变。结果ASHL母鼠所产子鼠中，部分(3／7)出现听觉损伤，并发现其血清中特异性抗体水平升高，内耳出现免疫炎性病理损伤。非ASHL母鼠和对照组母鼠所产子代未见明显异常。结论ASHL雌鼠所产子代可出现感音神经性聋，其内耳损伤和功能障碍极可能与针对内耳组织的自身免疫反应(尤其是体液免疫)有关。     

Gadolinium contrast-enhanced MRI reveals cystic lateral semicircular canal contents

Conclusion: Contrast-enhanced magnetic resonance imaging (MRI) reveals variations in the endolymphatic morphology of the cystic lateral semicircular canal (CLSC) that correlate with inner ear function. This report is the first to suggest a relationship between the morphology and function of this common inner ear malformation in clinical cases. Objectives: This study investigated the radiological and functional findings of a common inner ear malformation using computed tomography (CT), gadolinium contrast-enhanced magnetic resonance imaging (MRI), caloric testing, and cervical and ocular vestibular evoked myogenic potential (VEMP) testing. Method: Four ears in three patients who were radiologically diagnosed with a CLSC and a normal cochlea on high-resolution CT and contrast-enhanced MRI were included. Semicircular canal and vestibular functions were analyzed using the caloric test and cervical and ocular VEMP testing. Results: Unilateral and bilateral cystic canals were found in two and one patients, respectively. In the first patient, the malformed vestibule and cystic space were separate on imaging, and perilymph filled the cystic space. The functional test results were normal. In the second patient, endolymph filled both cystic spaces, and the functional responses were poor. In the third patient, endolymph filled the cystic space, and the ear did not respond during functional testing.     

多层螺旋CT对先天性内耳发育畸形的诊断价值

目的探讨多层螺旋CT(multi-slice computed tomography，MSCT)对先天性内耳发育畸形的诊断价值。方法对44例先天性感音神经性聋患者做MSCT横断面螺旋方式扫描及多平面重建(multi-planar reformation，MPR)，必要时做单侧重叠放大重建，并利用容积漫游技术(volume rendering technique，VRT)对骨迷路进行三维重建。结果44例患者中25例CT表现正常，19例(36耳)表现为内耳发育畸形。畸形有以下几种：Michel型(1耳次)，共同腔畸形(3耳次)，不完全分隔Ⅰ型(3耳次)，不完全分隔Ⅱ型(Mondini型，5耳次)，前庭及半规管畸形(14耳次)，前庭导水管扩大(16耳次，其中6耳次伴随其他畸形)，内耳道畸形(8耳次均伴随其他畸形)。36耳畸形中33耳MSCT横断面图像和MPR图像、VRT图像均可以清晰的显示畸形的部位和程度，其中VRT图像可以直观、立体地显示畸形的空间形态结构；3耳水平半规管短小畸形患者VRT图像较断面图像更好的显示了畸形的部位和程度。结论MSCT提高了横断面图像以及MPR、VRT图像的空间分辨率。VRT图像直观、立体的显示了骨迷路畸形的空间形态结构，并且可以通过旋转多方位观察畸形的形态。MSCT扫描结合VRT可更加准确的对内耳骨迷路畸形的部位和程度做出诊断，加深了我们对各种畸形的理解，有助于人工耳蜗植入手术计划的制定。