Does CISS MRI Reliably Depict the Endolymphatic Duct in Children with and without Vestibular Aqueduct Enlargement?

BACKGROUND AND PURPOSE: High-resolution CT is the mainstay for diagnosing an enlarged vestibular aqueduct (EVA), but MR imaging may be an appealing alternative, given its lack of ionizing radiation exposure. The purpose of this study was to determine how reliably MR imaging demonstrates the endolymphatic duct and endolymphatic duct enlargement in hearing-impaired children. MATERIALS AND METHODS: We performed a retrospective review of temporal bone high-resolution CT and MR imaging of hearing-impaired children evaluated between 2017 and 2020. Vestibular aqueduct diameter was measured on high-resolution CT. The vestibular aqueducts were categorized as being enlarged (EVA+) or nonenlarged (EVA-) using the Cincinnati criteria. The endolymphatic ducts were assessed on axial high-resolution CISS MR imaging. We categorized endolymphatic duct visibility into the following: type 1 (not visible), type 2 (faintly visible), and type 3 (easily visible). Mixed-effect logistic regression was used to identify associations between endolymphatic duct visibility and EVA. Interreader agreement for the endolymphatic duct among 3 independent readers was assessed using the Fleiss κ statistic. RESULTS: In 196 ears from 98 children, endolymphatic duct visibility on MR imaging was type 1 in 74.0%, type 2 in 14.8%, and type 3 in 11.2%; 20.4% of ears were EVA+ on high-resolution CT. There was a significant association between EVA+ status and endolymphatic duct visibility (P < .01). Endolymphatic duct visibility was type 1 in 87.1%, type 2 in 12.8%, and type 3 in 0% of EVA- ears and type 1 in 22.5%, type 2 in 22.5%, and type 3 in 55.0% of EVA+ ears. The predicted probability of a type 3 endolymphatic duct being EVA+ was 0.997. There was almost perfect agreement among the 3 readers for distinguishing type 3 from type 1 or 2 endolymphatic ducts. CONCLUSIONS: CISS MR imaging substantially underdiagnoses EVA; however, when a type 3 endolymphatic duct is evident, there is a >99% likelihood of an EVA.

Endolymphatic Duct Blockage as a Surgical Treatment Option for Ménière's Disease.

Endolymphatic duct blockage is a relatively new treatment option for Ménière's disease, aiming to reduce vertigo attacks while sparing hearing and equilibrium. After a regular mastoidectomy, the posterior semicircular canal is identified, and Donaldson's line is determined. This is a line through the horizontal semicircular canal, crossing the posterior semicircular canal. The endolymphatic sac is usually found at this site under the posterior semicircular canal. The bone of the endolymphatic sac and the dura are thinned until the sac is skeletonized, after which the endolymphatic duct is identified. The duct is then blocked with a titanium clip. Using a computerized tomography (CT) scan, the position is confirmed. Follow-up visits take place 1 week, 6 weeks and 1 year after surgery. To this day, only one prospective trial assessing this method has been conducted, comparing this new method to endolymphatic sac decompression. Results of the duct blockage are promising, with 96.5% of the patients free of vertigo after 2 years. However, further research is required.

A comparison of endolymphatic duct blockage, endolymphatic sac drainage and endolymphatic sac decompression surgery in reversing endolymphatic hydrops in Meniere's disease.

BACKGROUND: To explore the differences between endolymphatic duct blockage, endolymphatic sac drainage and endolymphatic sac decompression surgery in the reversal of endolymphatic hydrops (EH) in patients with intractable Meniere's disease (MD). METHODS: A total of 27 MD patients receiving endolymphatic duct blockage surgery (n = 10), endolymphatic sac drainage surgery (n = 9) and endolymphatic sac decompression surgery (n = 8) underwent gadolinium-enhanced inner ear magnetic resonance imaging (MRI) scans prior to, 2 weeks after and at > 12 months following surgery. RESULTS: In the group with endolymphatic duct blockage, the second MRI revealed no changes in EH, whereas the third MRI revealed a reversal of vestibular EH in 3 patients and a downgrading of cochlear hydrops in 2 of these 3 patients, who presented with an improvement in their hearing and complete control of vertigo. In the group with endolymphatic sac drainage, the second MRI showed a reversal of EH in 4 patients, and no changes in EH in the remaining 5 patients, whereas the third MRI showed that those 4 patients who presented with a reversal of EH at the second MRI stage remained unchanged except a recurrence of vestibular hydrops in 1 patient. All 4 patients exhibited a complete control of vertigo, but hearing improved in 1, worsened in 1 and remained unchanged in 2. In the group with endolymphatic sac decompression, both the second and third MRI examination revealed no reversal of EH. CONCLUSIONS: The present study has shown that both endolymphatic duct blockage surgery and endolymphatic sac drainage surgery have the potential to reduce EH in certain MD patients, but none of the patients receiving endolymphatic sac decompression surgery showed reversal of their EH.

3 Tesla MR imaging of the large endolymphatic duct and sac anomaly with audiological correlation.

PURPOSE: Large endolymphatic duct and sac (LEDS) is one of the most common imaging abnormalities in congenital sensorineural hearing loss and is frequently seen with coexistent cochlear anomalies, especially incomplete partition type II. However, MRI findings of accompanying cochlear and especially modiolar dysplasias may be subtle. The purpose of this study is to evaluate the imaging findings of LEDS with high-resolution imaging at 3 T and correlate with the audiological data. METHODS: 3 T temporal bone MRIs of 54 ears in 30 LEDS patients were retrospectively evaluated. The cochlear dysmorphism and modiolar deficiency were assessed qualitatively and quantitatively. The severity of LEDS anomaly, the signal changes within the LEDS and cochlea were also noted. The imaging findings were correlated to the audiological data. RESULTS: The cochlea was abnormal in 77.8% of the ears with an isolated modiolar deficiency in 11.1%. Cochlea and modiolus were completely normal in 11.1% of the ears. In 63% of the ears X-distance was increased. T2 hypointensity within LEDS and cochlea were detected in 42.6%, and 7.4% of the ears, respectively. The median diameters of LEDS were higher in ears with severe to profound HL than ears with normal to moderate HL (p < 0.05). The X-distance, presence of T2 hypointensity within LEDS, and diameters of modiolus did not show statistical correlation with the audiographic data. CONCLUSION: High-resolution 3 T imaging of patients with LEDS anomaly revealed a spectrum of cochlear anomalies, but up to 11.1% of the ears had no underlying anomaly despite severe (endolymphatic duct/sac) dilatation and/or profound HL.

MRI Evaluation of the Normal and Abnormal Endolymphatic Duct in the Pediatric Population: A Comparison with High-Resolution CT.

BACKGROUND AND PURPOSE: An enlarged vestibular aqueduct is the most commonly reported imaging abnormality in children with sensorineural hearing loss. MR imaging is often used to evaluate pediatric sensorineural hearing loss; however, there are no well-established size criteria on MR imaging to diagnose an enlarged endolymphatic duct. The first purpose of the study was to determine a range of normal endolymphatic duct sizes on MR imaging and compare it with that in high-resolution CT. The second purpose was to assess the sensitivity and specificity of MR imaging in diagnosing an enlarged endolymphatic duct in patients with an enlarged vestibular aqueduct on CT. MATERIALS AND METHODS: Endolymphatic duct midaperture measurements were analyzed in 52 patients with no history of sensorineural hearing loss. Comparison of CT and MR imaging was made in a second cohort of 41 patients with a normal midaperture width on CT. The sensitivity and specificity of MR imaging were then evaluated in a third cohort of 24 patients with a documented enlarged vestibular aqueduct on CT. RESULTS: In 94 ears, normal endolymphatic duct midaperture measurements ranged from 0 to 0.9 mm on MR imaging. A significant correlation (P <.001) and moderate agreement were found between CT and MR imaging in 81 ears with a normal vestibular aqueduct on CT. Twenty-four patients had bilateral (n = 14) or unilateral (n = 10) enlarged vestibular aqueducts on CT, and the sensitivity and specificity of MR imaging were 97% and 100%, respectively, for a diagnosis of an enlarged endolymphatic duct. CONCLUSIONS: MR imaging measurements of the normal endolymphatic duct are similar to those established for CT. MR imaging is a useful tool for the diagnosis of enlarged vestibular aqueduct.

Significance of high signal intensity in the endolymphatic duct on magnetic resonance imaging in ears with otological disorders.

BACKGROUND: High signal intensity in the endolymphatic duct (ED) is occasionally observed on magnetic resonance imaging (MRI) in ears that have otological disorders. OBJECTIVE: The signal intensity (SI) in the ED on post-contrast MRI was investigated in subjects with various otological disorders, and the meaning of high SI in the ED was evaluated. MATERIAL AND METHODS: 392 patients with otological disorders and 21 controls without otological symptoms underwent 3 T MRI. The SIs of the ED and the cerebellum were measured, the SI ratio (SIR) was calculated, and ears with SIR ≥4 were identified. RESULTS: A high SIR was identified in the ED of 3.7% of ears affected by definite Meniere's disease (dMD), 100% of ears affected by large vestibular aqueduct syndrome (LVAS), and 7.1% of ears with no otological symptoms. On the whole, a significant relationship was found between the existence of vestibular or cochlear EH and the SIR in the ED. CONCLUSION: The MRI finding of high SI in the ED may indicate the mechanism of inner ear disturbances in ears with otological disorders, especially in those with LVAS, and it may suggest an underlying disorder in some ears in which otological symptoms are not apparent.

Detailed MR imaging assessment of endolymphatic hydrops in patients with SLC26A4 mutations.

OBJECTIVE: Mutations in SLC26A4 represent the second most common mutations in deafness patients. The majority of patients with SLC26A4 mutations have a large vestibular aqueduct (LVA). Recently, some reports showed the presence of endolymphatic hydrops (ELH) in patients with LVA on the basis of high-resolution enhanced 3T-MRI. However, detailed evaluation has not been performed. We provide the first report on ELH in LVA patients with biallelic SLC26A4 mutations. In this study, we focused on 1) the findings of ELH in LVA patients with biallelic SLC26A4 mutations, and 2) the findings of the endolymphatic duct (ED) and endolymphatic sac (ES) by using two different gadodimide (Gd) enhancement methods. SUBJECTS AND METHODS: Five patients with SLC26A4 mutations underwent enhanced 3T-MRI using the intratympanic (IT) or intravenous (IV) injection of Gd for the diagnosis ELH. RESULTS: All of the patients had ELH in at least one ear. ELH was identified in the vestibule (8/10 ears) as well as in the cochlea (7/10 ears). With regard to the ED and ES, all ears for which MRI was performed with an IT injection of Gd had black areas in the ES or VA or both; however, all of the ears receiving an IV injection had no black areas and were well enhanced. CONCLUSIONS: A majority of the patients had severe ELH in the cochleo-vestibular endolymph, with two different patterns observed in the MRI findings of the ED and ES.

A Micro-CT and Synchrotron Imaging Study of the Human Endolymphatic Duct with Special Reference to Endolymph Outflow and Meniere's Disease.

Meniere's disease remains enigmatic, and has no treatment with sufficient evidence. The characteristic histopathological finding is endolymphatic hydrops, suggesting either an overproduction or decreased reabsorption of endolymph in the human inner ear. This study presents the first analysis of the vascular plexus around the human endolymphatic duct using micro computed tomography and coherent synchrotron radiation with phase contrast imaging. Using a software program, data were processed by volume-rendering with scalar opacity mapping to create transparent three-dimensional reconstructions. A rich vascular plexus was discovered around the endolymphatic duct that drained into collecting channels, linked to the vestibular venous outflow system. This network is believed to make up the principal route for endolymph outflow, and its associated malfunction may result in endolymphatic hydrops and Meniere's disease.

Magnetic resonance imaging of endolymphatic space in patients with sensorineural hearing loss: comparison between fluctuating and idiopathic sudden sensorineural hearing loss.

Background: Recently, 3-Tesla magnetic resonance imaging (MRI) after an intravenous gadolinium injection has been used to describe the endolymphatic space (ELS).Objectives: This study described the histopathological differences between idiopathic sudden sensorineural hearing loss (ISSNHL) and fluctuating sensorineural hearing loss (FSNHL) by examining the ELS. Additionally, the relationship between the affected cochlear and vestibular ELS/total fluid space (TFS) volume ratio and the duration from the onset to MRI in patients with FSNHL were evaluated.Material and methods: This study included 205 individuals without vertigo: 47 controls, 94 with ISSNHL, and 64 with FSNHL. The TFS and ELS volumes were measured and the ELS/TFS volume ratios (%) were evaluated.Results: The cochlear and vestibular ELS/TFS volume ratios of the affected ear in patients with FSNHL were significantly higher than that in those with ISSNHL. There was no correlation between the duration from FSNHL onset to the MRI scan in the affected cochlea and vestibule.Conclusion and significance: There were differences in the form of hearing fluctuation and the extended ELS volume between ISSNHL and FSNHL. ISSNHL cases with severe ELS extension were likely to change to FSNHL.

Magnetic resonance-based volumetric measurement of the endolymphatic space in patients with Meniere's disease and other endolymphatic hydrops-related diseases.

OBJECTIVE: To employ magnetic resonance imaging (MRI) to measure the volume of the inner ear endolymphatic space (ELS) in patients with acute low-tone sensorineural hearing loss (ALHL), sudden deafness (SD), cochlear Meniere's disease (cMD), and unilateral MD (uMD) compared with control subjects (CS) with chronic rhinosinusitis. METHODS: Forty-one patients with ALHL, 82 with SD, 48 with cMD, 72 with uMD, and 47 CS participated in the study. With the exception of all uMD patients, none of the subjects had vertigo. Images of the inner ear fluid space, positive perilymph signal, and positive endolymph signal were acquired using a 3-T MRI scanner. Three-dimensional images were reconstructed semi-automatically by using anatomical and tissue information to fuse the inner ear fluid space images and the ELS images. RESULTS: The cochlear ELS/total fluid space (TFS) volume ratio was 10.2±6.7% (mean±standard deviation) in the CS group, 12.1±5.7% in ALHL patients, 15.2±8.7% in SD patients, 18.1±8.2% in cMD patients, and 21.9±16.4% in uMD patients. The vestibular ELS/TFS volume ratio was 17.7±10.2% in the CS group, 18.9±8.3% in ALHL patients, 19.9±11.3% in SD patients, 22.5±13.7% in cMD patients, and 35.7±24.1% in uMD patients. The cochlear ELS/TFS volume ratio in patients with uMD was similar to that in the cMD group and significantly higher than that in the CS, ALHL, and SD groups (CS=ALHL

MR Imaging in Menière Disease: Is the Contact between the Vestibular Endolymphatic Space and the Oval Window a Reliable Biomarker?

BACKGROUND AND PURPOSE: No reliable MR imaging marker for the diagnosis of Menière disease has been reported. Our aim was to investigate whether the obliteration of the inferior portion of the vestibule and the contact with the stapes footplate by the vestibular endolymphatic space are reliable MR imaging markers in the diagnosis of Menière disease. MATERIALS AND METHODS: We retrospectively enrolled 49 patients, 24 affected by unilateral sudden hearing loss and 25 affected by definite Menière disease, who had undergone a 4-hour delayed 3D-FLAIR sequence. Two readers analyzed the MR images investigating whether the vestibular endolymphatic space bulged in the third inferior portion of the vestibule contacting the stapes footplate. This sign was defined as the vestibular endolymphatic space contacting the oval window. RESULTS: We analyzed 98 ears: 27 affected by Menière disease, 24 affected by sudden sensorineural hearing loss, and 47 that were healthy. The vestibular endolymphatic space contacting the oval window showed an almost perfect interobserver agreement (Cohen κ = 0.87; 95% CI, 0.69-1). The vestibular endolymphatic space contacting oval window showed the following: sensitivity = 81%, specificity = 96%, positive predictive value = 88%, and negative predictive value = 93% in differentiating Menière disease ears from other ears. The vestibular endolymphatic space contacting the oval window showed the following: sensitivity = 81%, specificity = 96%, positive predictive value = 96%, negative predictive value = 82% in differentiating Menière disease ears from sudden sensorineural hearing loss ears. CONCLUSIONS: The vestibular endolymphatic space contacting the oval window has high specificity and positive predictive value in differentiating Menière disease ears from other ears, thus resulting in a valid tool for ruling in Menière disease in patients with mimicking symptoms.

Comparison of Endolymphatic Duct Dimensions and Jugular Bulb Abnormalities Between Meniere Disease and a Normal Population.

BACKGROUND: The pathogenesis of Meniere disease (MD) has not been fully understood. According to the widely accepted theory, imbalances due to overproduction and/or impaired absorption of endolymph may cause endolymphatic hydrops, which is the hallmark pathological finding in MD. Some developmental temporal bone abnormalities may impair endolymph circulation and absorption, and these abnormalities could be a part of MD pathophysiology. However, structural features of the temporal bone cannot explain MD pathophysiology definitively. The authors aimed to determine the length and width of the endolymphatic duct (ED) along with jugular bulb (JB) abnormalities in MD patients and normal controls using high-resolution computed tomography, and to discuss the results supporting and opposing endolymphatic hydrops based on the data obtained. METHODS: Thirty-six ears of 18 patients with unilateral MD and 34 ears of 17 normal subjects were enrolled. Jugular bulb abnormalities and ED dimensions were evaluated in 3 groups: affected and unaffected ears of MD patients, and healthy controls. The ED dimensions and JB abnormalities were evaluated with high-resolution computed tomography. RESULTS: The ED was found to be significantly shorter and narrower in the affected ears of the MD patients than in the healthy control group. In addition, more JB abnormalities were detected in the affected ears of the MD patients than in the healthy control group. However, there was no difference between the affected and unaffected ears of the MD patients. CONCLUSION: Structural ED abnormalities and JB abnormalities may be predisposing factors for the development of Meniere disease, but cannot fully explain MD pathophysiology.

Visualization and assessment of saccular duct and endolymphatic sinus.

CONCLUSION: The saccular duct and endolymphatic sinus run in the bony groove, before reaching the orifice of the vestibular aqueduct. We first clinically visualized this sulciform groove using three-dimensional (3D) cone beam CT images. This strategy can be useful to assess the condition of the saccular duct and endolymphatic sinus concerning the longitudinal flow system of endolymph. OBJECTIVE: To assess the saccular duct and endolymphatic sinus in the endolymphatic system in order to advance clinical studies on inner ear dysfunction. METHODS: The sulciform groove of the saccular duct and endolymphatic sinus of human subjects was analyzed by cone beam CT and compared with that of a cadaver. RESULTS: We could obtain reconstructed 3D CT images of the sulciform groove of the saccular duct and endolymphatic sinus using several CT window levels.

Computed tomography findings in large vestibular aqueduct syndrome.

CONCLUSIONS: Patients with large vestibular aqueduct syndrome (LVAS) have disturbed morphogenesis of bony labyrinth. Semicircular canal anomalies are common in LVAS. OBJECTIVE: To describe the additional inner ear anomalies on CT imaging in pediatric patients with LVAS, and to investigate the lateral semicircular canal (LSCC) anomalies associated with LVAS by measurement of the LSCC bony island width. PATIENTS AND METHODS: We retrospectively reviewed the digitally stored temporal bone CT imaging obtained for 23 patients with LVAS, additional inner ear anomalies were noted, and measurements of the LSCC bony island width were made on axial CT scans on the workstation. Measurements were compared to the normative data obtained from 20 patients without sensorineural hearing loss. RESULTS: Of the 23 patients (bilateral in 22 and unilateral in 1), additional inner ear malformations were identified in 21 cases presenting either singly or in combination. A small LSCC bony island (<3 mm in diameter) appeared highly typical; vestibule and LSCC anomalies were identified in 13 cases (26 ears) based on visual inspection combined with abnormal measurements. Dehiscence of the superior and/or posterior semicircular canal was identified in 19 ears, and Mondini deformity was identified in 6 ears.

Can magnetic resonance imaging provide clues to the inner ear functional status of enlarged vestibular aqueduct subjects with PDS mutation?

OBJECTIVES: The goal of this study was to characterize the signal intensity (SI) pattern in the endolymphatic duct/sac from T2-weighted spin echo magnetic resonance (MR) images and T2*-weighted 3-dimensional (3-D) constructive interference in steady state (CISS) MR images that were obtained from a homogenous group of patients with an enlarged vestibular aqueduct (EVA) associated with SLC264 (PDS) mutations. STUDY DESIGN: A retrospective study. SETTING: Tertiary referral center. PATIENTS: Eleven subjects (22 ears), with at least 1 SLC26A4 mutation and bilateral EVA confirmed by temporal bone computed tomography, were enrolled. INTERVENTION: The MR images of 22 ears were reviewed retrospectively. MAIN OUTCOME MEASURES: The SI of the endolymphatic sac (ES) from 2 sequences were compared and reviewed. The presence of anomalies of the vestibule were also evaluated. In addition, the caloric test results were also reviewed to characterize the vestibular function in a subset of our cohort (12 ears). RESULTS: T2*-weighted 3-D CISS MR images revealed a more variable SI in the enlarged endolymphatic system than did the T2-weighted images. There was a hierarchy for the order of SI loss from the endolymphatic system on the T2*-weighted 3-D CISS MR images. There were 3 cases where the SI loss from the intraosseous ES, on the T2*-weighted 3-D CISS images, was associated with an abnormal caloric response. CONCLUSION: The SI of the ES observed on T2*-weighted 3-D CISS images of EVA patients, with SLC26A4 mutations, showed a distinctive pattern, and the results from this study suggest a potential role for the MR imaging in providing physicians with better information about the functional status of the inner ear.

[Large endolymphatic duct and sac syndrome : part 2: clinical manifestations]. / Der erweiterte Ductus und Saccus endolymphaticus : Teil 2: Klinische Manifestationen.

OBJECTIVE: The aim of this study was to clarify the clinical course of large endolymphatic duct and sac syndrome (LEDS). Although LEDS is the most common form of radiologically detectable inner ear malformation associated with sensorineural hearing loss (SNHL), it is relatively unknown in the German-speaking countries. We hoped to derive useful pointers for clinical care. METHODS: We evaluated the clinical audiometric records and imaging findings of 169 patients with clinically suspected inner ear malformation seen between 1994 and 2003. Following identification of all LEDS cases, we serially investigated the anamnestic and functional data with regard to severity and course. RESULTS: Among 169 patients, 17 (median age 12 years; 12 females) showed LEDS. A total of 28 ears were affected. Clinically, most cases were of prelingual or perilingual onset and displayed steady or fluctuatingly progressive severe SNHL with emphasis on the high frequencies or deafness. Episodes of sudden hearing loss were relatively frequent. No correlation could be demonstrated between the severity of morphological changes and the degree of SNHL. CONCLUSION: Progression of SNHL and episodes of sudden hearing loss were seen mainly in late childhood or adolescence. This should be taken into account when informing and advising patients and planning therapy.

[Large endolymphatic duct and sac syndrome (LEDS) : part I: analysis of imaging findings]. / Der erweiterte Ductus und Saccus endolymphaticus : Teil 1: Analyse bildgebender Befunde.

OBJECTIVE: Large endolymphatic duct and sac (LEDS) syndrome is the most common radiologically detectable form of inner ear malformation (IEM) associated with sensorineural hearing loss (SNHL). Nevertheless, it is relatively unknown in the German-speaking countries. METHODS: Among all patients referred from ear, nose, and throat specialists to the radiology department with clinically suspected IEM between 1994 and 2003, we identified the cases of LEDS. The retrospective study included clinical records, high-resolution computed tomography, and magnetic resonance imaging. RESULTS: Of 169 patients, 17 (median age 12 years; 12 females) showed LEDS. A total of 28 ears were affected. Ten patients (6%; 15 ears) had isolated LEDS, while seven patients showed additional IEM (4%; 13 ears). The most frequent of these was dysplastic vestibule (13/13 ears), followed by Mondini deformity (10/13 ears) and dilated semicircular canals (7/13 ears). Three of 13 ears revealed severe IEM of the cochlea, vestibule, and semicircular canals. No correlation could be demonstrated between the severity of morphological changes and the degree of SNHL. CONCLUSION: LEDS may be an underestimated cause of SNHL. Imaging is necessary for a confident diagnosis.

Can a fixed measure serve as a pertinent diagnostic criterion for large vestibular aqueduct in children?

BACKGROUND: A vestibular aqueduct midpoint width greater than 1.50 mm is currently considered to be pathognomonic for a large vestibular aqueduct syndrome. OBJECTIVE: To analyse the diameter of the vestibular aqueduct in children as a function of age and consequently to determine if a fixed measure could serve as a pertinent diagnostic criterion. MATERIALS AND METHODS: This was a retrospective study of 200 high-resolution CT scans of the ear in 100 patients aged 0-16 years and from various paediatric medical departments. On each CT scan, the lateral semicircular canal diameter, the vestibular aqueduct midpoint width between the external aperture and common crus, and the vestibular aqueduct external aperture diameter were measured. Spearman's rank test and the Mann-Whitney correlation test were used for an integrated statistical analysis. RESULTS: There was no statistically significant variability in vestibular aqueduct diameter as a function of age or sex of patients. CONCLUSION: A CT scan threshold value, fixed and independent of age and sex, is thus legitimate for the diagnosis of vestibular aqueduct dilatation.