High-resolution Computed Tomography Temporal Bone Research Articles

Analyses of the clinical characteristics of unilateral conductive hearing loss with intact tympanic membrane

To analyze the clinical characteristics of unilateral conductive hearing loss with intact tympanic membrane, and summarize the key diagnostic points, differential diagnosis and observe the effects of surgical treatment. We reviewed data from 82 patients with unilateral conductive hearing loss with intact tympanic membranes who accepted the exploratory tympanotomy from April 2011 to September 2013. There were 41 males and 41 females, aged from 7 to 66( averaged 26.5±13.7)years, with a history of one month to 50 years. The history, clinical symptoms, audiological evaluation, high resolution temporal bone CT, the results of surgical exploration and hearing reconstruction were analyzed. The exploratory tympanotomy revealed 43 cases of congenital middle ear malformations (52.4%), 22 cases of otosclerosis (26.8%), eight cases of congenital cholesteatoma (9.8%), six cases of trauma induced conductive hearing loss (7.3%), three cases of congenital ossicular malformations with congenital cholesteatoma (3.7%). Progressive hearing loss was common in patients with otosclerosis and congenital cholesteatoma, and patients with congenital middle ear malformations described their hearing loss since childhood. High resolution temporal bone CT of congenital middle ear malformation, trauma induced conductive hearing loss, congenital cholesteatoma diagnosis rate was 40.0%, 50.0%, and 83.3% respectively. The preoperative air-conductive threshold of patients with absence of the oval window were increased to (66.9±1.1)dBHL, the preoperative bone-conductive threshold achieved (28.3±10.4)dBHL at 2 000 Hz. While patients with stapes fixation and that with ossicular chain discontinuity were (27.2±9.7)dBHL and (17.8±8.8)dBHL(P=0.000)respectively. Through the tympanic exploration with endaural incision under the microscope, different hearing reconstruction were applied according to different lesions. After the operation, the hearing level of 52 patients with return visit were improved, the mean air-conductive threshold were decreased from (60.0±11.4)dBHL to (32.2±12.1)dBHL(P=0.000); and the mean ABG were decreased from (43.2±12.0)dB to (16.3±9.4)dB(P=0.000). Congenital middle ear malformations, otosclerosis, congenital cholesteatoma are the most common causes in unilateral conductive hearing loss with an intact tympanic membrane. The diagnosis rate can be improved by analyzing the clinical features. Through exploratory tympanotomy and hearing reconstruction, we can clarify the diagnosis and achieve a satisfying hearing recover.

Prevention and management of hearing loss in syndromic craniosynostosis: A case series

ObjectiveTo assess the audiological profile in a cohort of children affected by syndromic craniosynostosis. MethodsEleven children with Apert syndrome (n=4), Saethre-Chotzen syndrome (n=3), Muenke syndrome (n=2), Crouzon syndrome (n=1) and Pfeiffer syndrome type 1 (n=1) were submitted to a complete audiologic evaluation including otoscopy, pure-tone audiometry, tympanometry and acoustic reflex testing, ABR, otoacustic emissions, temporal bone High Resolution CT (HRCT) scan. The main outcome measures were prevalence, type and severity of hearing loss, prevalence of chronic otitis media, correlation with the time of first surgical correction. ResultsSeven of 11 patients (64%) presented hearing loss (HL), conductive in 3/7 patients (43%) and mixed in 4/7 (57%). No patients showed a purely sensorineural HL. All hearing impaired patients displayed middle ear disorders: the patients with conductive HL had otitis media with effusion (OME) and 3/4 patients with mixed HL showed tympanic alterations or cholesteatoma. A bilateral vestibular aqueduct enlargement was detected by HRCT scan in one normal hearing patient. The ABRs resulted normal in all cases. ConclusionOur study confirms the high prevalence of otologic diseases in such patients. In contrast with previous studies, middle ear disorders were responsible for the hearing impairment also in patients with mixed HL due to secondary inner ear damage. These findings restate the necessity of a close audiologic follow-up. We did not detect the specific ABR abnormalities previously reported, possibly because of an early correction of the cranial vault malformations.

Is cholesteatoma a precursor of verrucous carcinoma: A diagnostic dilemma

Verrucous carcinoma is an unusually well-differentiated variant of squamous cell carcinoma, characterized by local invasion and cytologically benign appearance. We report a case of 52-year-old male who presented with postauricular growth and cholesteatoma in the right ear. High-resolution computed tomography temporal bone showed an enhancing soft tissue mass lesion extending into the mastoid, external auditory canal, and middle ear. Growth was histopathologically confirmed to be verrucous carcinoma extending from the cholesteatoma in mastoid cavity. Review of literature confirms the rarity of cases of cholesteatoma which could progress and present as verrucous carcinoma in the postauricular region.

Imaging Modality of Choice for Pre-Operative Cochlear Imaging: HRCT vs. MRI Temporal Bone.

Congenital inner ear malformations occur as a result of the arrest or aberrance of inner ear development due to the heredity, gene mutation or other factors. Ever since the availability of cochlear implants, pre-operative evaluation by imaging of temporal bone has gained much attention. Precise selection of the candidate for cochlear implant dependent on preoperative radiological investigations. Only CT (Computed Tomography) and MRI (Magnetic Resonance Imaging) can provide a better picture of anatomy and pathology. To compare pre-operative imaging findings of both MRI and High Resolution Computed Tomography (HRCT) temporal bone and to find the best modality of choice in patients with bilateral profound Sensorineural Hearing Loss (SNHL). This was a prospective, longitudinal, observational study conducted between June 2010 to November 2012. A total of 144 temporal bones were evaluated in 72 children with bilateral profound SNHL with congenital inner ear malformations. Each temporal bone was considered as a single case (144 cases). All the patients underwent HRCT and high field MRI study. MRI study included T2 W axial 3D FIESTA (Fast Imaging Employing Steady-state Acquisition) sequence. Anatomic abnormalities in each temporal bone were described and noted. For complete and better evaluation of Vestibulo-Cochlear Nerve (VCN) additional 3D oblique parasagittal view was taken perpendicular to the internal auditory canal with a small Field Of View (FOV). HRCT and MRI allowed accurate detection of inner ear malformations in children with bilateral SNHL. Majority of the patients presented with multiple structural abnormalities of inner ear. The common pathologies detected in the study were semicircular canal abnormality (89/144) followed by cochlear abnormalities (39/144). Most common cochlear abnormality was Mondini's deformity (14/144). MRI demonstrated absent of vestibulo-cochlear nerve in 15 cases. Few abnormalities of inner ear are better illustrated on CT, while others are better showed on MRI. Hence, neither HRCT nor MRI of the brain and temporal bones appears to be adequate imaging modality rather they are complementary to each other for pre-operative imaging of cochlear implantation.

Comparison of Preoperative Temporal Bone HRCT and Intraoperative Findings in Patients with Chronic Otitis Media

Objective: The aim of the present study was to investigate the diagnostic confidence level of preoperative 160-slice computed tomography (CT) findings compared with that of perioperative findings about anatomic variations in the structure of the facial canal, lateral semicircular canal, and dural plate. Materials and Methods: Fifty-five patients who presented with middle ear pathology to Department of Otolaryngology, Afyon Kocatepe University Faculty of Medicine were included in the study, and the mean age was 42 (±15.55) years. Preop- erative CT images of the temporal bone were obtained by an 80-detector row CT scanner. Results: The sensitivity, specificity, and positive and negative predictive values of preoperative high-resolution CT (HRCT) were 52%, 88%, 73%, and 75%, respectively, for determining the presence of facial canal dehiscence; 50%, 89%, 71%, and 76%, respectively, for determining the presence of tympanic segment dehiscence; 71%, 96%, 71%, and 96%, respectively, for determining the presence of lateral semicircular canal dehiscence; and 100%, 96%, 50%, and 100%, respectively, for detecting the presence of dural plate defects. Conclusion: The compatibility of HRCT findings with surgical findings in determining the presence of dehiscence of the facial canal and its tympanic segment was moderate, while it was good in determining the presence of dehiscence of the lateral semicircular canal and the defect of the dural plate.

Clinical and Radiological Predictability of Aditus Patency in Mucosal COM with Sclerosed Mastoid: An Analytical Study

ABSTRACT Objectives To evaluate the predictability of aditus patency in mucosal chronic otitis media (COM) with sclerosed mastoid using clinical and radiological tests. Study design Prospective study. Materials and methods Thirty-five cases of mucosal COM with sclerosed mastoid were taken for antrotomy with tympanoplasty. The preoperative evaluation of aditus patency was done using clinical examination, inflation deflation test for Eustachian tube function and high-resolution computed tomography (HRCT) temporal bone. The intraoperative patency was tested by water test. Results This study shows that there is statistically insignificant correlation between duration of discharge, tympanosclerosis and Eustachian tube function with aditus patency. There is statistically significant relationship between HRCT temporal bone and aditus patency (p < 0.0001). Conclusion High-resolution computed tomography temporal bone is a reliable predictor for aditus patency and we recommend routine use in sclerosed mastoid before all tympanoplasties for best results. How to cite this article Varma A, Maithani T, Agrahari AK, Pandey AK, Singh VP. Clinical and Radiological Predictability of Aditus Patency in Mucosal COM with Sclerosed Mastoid: An Analytical Study. Int J Otorhinolaryngol Clin 2015;7(3):121-124.

A Novel Temporal Bone Simulation Model Using 3D Printing Techniques.

An inexpensive temporal bone model for use in a temporal bone dissection laboratory setting can be made using a commercially available, consumer-grade 3D printer. Several models for a simulated temporal bone have been described but use commercial-grade printers and materials to produce these models. The goal of this project was to produce a plastic simulated temporal bone on an inexpensive 3D printer that recreates the visual and haptic experience associated with drilling a human temporal bone. Images from a high-resolution CT of a normal temporal bone were converted into stereolithography files via commercially available software, with image conversion and print settings adjusted to achieve optimal print quality. The temporal bone model was printed using acrylonitrile butadiene styrene (ABS) plastic filament on a MakerBot 2x 3D printer. Simulated temporal bones were drilled by seven expert temporal bone surgeons, assessing the fidelity of the model as compared with a human cadaveric temporal bone. Using a four-point scale, the simulated bones were assessed for haptic experience and recreation of the temporal bone anatomy. The created model was felt to be an accurate representation of a human temporal bone. All raters felt strongly this would be a good training model for junior residents or to simulate difficult surgical anatomy. Material cost for each model was $1.92. A realistic, inexpensive, and easily reproducible temporal bone model can be created on a consumer-grade desktop 3D printer.

Paediatric CT dose: a multicentre audit of subspecialty practice in Australia and New Zealand

To evaluate paediatric CT dosimetry in Australia and New Zealand and calculate size-specific dose estimates (SSDEs) for chest and abdominal examinations. Eight hospitals provided data from 12 CT systems for 1462 CTs in children aged 0-15. Imaging data were recorded for eight examinations: head (trauma, shunt), temporal bone, paranasal sinuses, chest (mass) and chest HRCT (high-resolution CT), and abdomen/pelvis (mass/inflammation). Dose data for cranial examinations were categorised by age and SSDEs by lateral dimension. Diagnostic reference ranges (DRRs) were defined by the 25th and 75th percentiles. Centralised image quality assessment was not undertaken. DRRs for 201 abdominopelvic SSDEs were: 2.8-4.7, 3.6-11.5, 8.5-15.0, 7.6-15, and 10.6-16.2 for the <15cm, 15-19cm, 20-24cm, 25-29cm and >30cm groups, respectively. For 147 chest examinations using these body width categories, SSDE DRRs were 2.0-4.4, 3.3-7.9, 4.0-9.4, 4.5-12, and 6.5-12. Kilovoltage peak (kVp), but not AEC or IR, was associated with SSDE (parameter estimate [standard error]: 0.12 (0.03); p < 0.0001). Australian and New Zealand paediatric CT DRRs and abdominal SSDEs are comparable to international data. SSDEs for chest examinations are proposed. Dose variations could be reduced by adjusting kVp. • SSDEs can be calculated for all patients, CT systems, and practices • Kilovoltage peak (kVp) has the greatest association with dose in similar-sized patients • Paediatric DRRs for CT are now available for use internationally.

Thickness of the Bony Otic Capsule: Etiopathogenetic Perspectives on Superior Canal Dehiscence Syndrome

The etiology of superior canal dehiscence (SCD) is controversial. An embryological perspective suggests that SCD may occur through the failure of postnatal bone formation over the superior semicircular canal (SC), whereas an acquired theory suggests that trauma or pressure from the overlying temporal lobe could break or gradually thin the SC. We infer the etiology of SCD by comparing the thickness of the bony otic capsule of the unaffected side of SCD patients with that of non-SCD participants. Twelve SCD patients (13 SCD ears and 11 normal ears) and 34 age-matched controls (68 ears) were included. The control group was subdivided into an aerated group (49 ears) and a nonaerated group (19 ears), as defined by the presence of air cells above the SC. A high-resolution temporal bone CT was performed in all participants. The thicknesses of the SC, horizontal canal (HC) and posterior canal (PC) of the unaffected ears of SCD patients were compared with those of the controls. The SC of the unaffected side in the SCD group (n = 11, 0.41 ± 0.23 mm) was significantly thinner than the one in the control group (n = 68, 0.64 ± 0.21 mm, p = 0.002). The HC and PC were also thinner in the SCD group (n = 24, 0.58 ± 0.11 and 1.39 ± 0.31 mm, respectively) than in the controls (0.70 ± 0.08 and 1.61 ± 0.32 mm; p < 0.0001 and p = 0.005, respectively). The SC, HC and PC thicknesses were also compared between the aerated and nonaerated ears within the control group. The SC was significantly thicker in the aerated group (0.73 ± 0.14 mm) than in the nonaerated group (0.60 ± 0.23 mm; p = 0.046); however, no significant difference was observed for the HC and PC thickness (aerated group, n = 49, 0.72 ± 0.07 and 1.67 ± 0.34 mm; nonaerated group, n = 19, 0.70 ± 0.09 and 1.59 ± 0.34 mm; p = 0.350 and p = 0.428, respectively). The bony otic capsule was significantly thinner in the SCD patients than in the controls. However, even within unaffected individuals, SCs lacking overlying air cells were also thinner than those with overlying air cells. These results suggest that both embryological and acquired factors affect the occurrence of SCD.

Connexin‐Related (DFNB1) Hearing Loss

Determine if routine computed tomography (CT) imaging is necessary in the workup for children with connexin-related (DFNB1) sensorineural hearing loss (SNHL). Case-control retrospective chart and imaging review. Tertiary care otolaryngology practice. High-resolution temporal bone CT scans of children (n = 21) with DFNB1 SNHL were compared to age-matched controls with either conductive hearing loss (CHL, n = 33) or a nonsyndromic, non-DFNB1 SNHL (n = 33). Sixteen measurements of cochleo-vestibular structures were recorded. Statistical analysis was performed using a repeated analysis of variance model that controlled for both age and gender. Area under the curve (AUC) and multidimensional AUC (MAUC) analyses were also performed. Overall, no statistically significant differences were found between the 3 experimental groups. In addition, comparisons between the DFNB1 and CHL groups, DFNB1 and non-DFNB1 SNHL groups, and CHL and non-DFNB1 SNHL groups failed to demonstrate any statistically significant differences. AUC and MAUC analyses also failed to detect any significant differences between the 3 groups. Patients with DFNB1 SNHL do not have significant anatomic differences on temporal bone CT scans when compared to non-DFNB1 SNHL and CHL control groups. Based on the above analysis, it is reasonable to avoid routine CT imaging of the temporal bones in children with known DFNB1 SNHL unless otherwise clinically indicated.

Correlation of high-resolution computed tomography temporal bone findings with intra-operative findings in patients with cholesteatoma

Aim: To evaluate the role of high-resolution computed tomography (HRCT) temporal bone in patients with active squamosal chronic otitis media (COM). Materials and Methods: Totally, 47 patients with active squamosal COM underwent preoperative HRCT temporal bone followed by surgery. Their intra-operative findings were considered as the gold standard and were compared and correlated with the radiological findings, to calculate the sensitivity, specificity, positive and negative predictive value of HRCT temporal bone. Results: According to the present study, HRCT was highly sensitive for detecting mastoid pneumatization, soft tissue extension, ossicular erosion, tegmen and sigmoid sinus erosion, and less sensitive for fallopian canal erosion and lateral sinus fistula. It was specific for all these parameters. Conclusion: The present study concludes that HRCT can be recommended not only in cases suspected with potential complications but also in all cases of COM to know the extent of disease, varied pneumatization, and the presence of anatomical variations, which should alert the clinician and guide in surgical approach and treatment plan.

Common features in patients with superior canal dehiscence declining surgical treatment.

BackgroundSuperior canal dehiscence (SCD) is a benign condition in which a surgical treatment may be considered depending on the patients’ tolerance of their symptoms. In this study, we aim to identify driving factors behind the patients’ choice of a surgical management over watchful waiting.MethodsSixty-two patients with cochlear and/or vestibular symptoms and a temporal bone high-resolution CT (HRCT) scan showing SCD were included in the study. All patients have been offered either surgical management or watchful waiting.ResultsOf these, 28 elected surgery and 34 declined it. The operated group showed more cochlear (6.6 vs. 2.4) symptoms than the non-operated group (P < 0.001) except for hypoacousis, but no significant difference (P = 0.059) was found for the number of vestibular symptoms between both groups (3.4 vs. 1.1). Footstep and eating hyperacousis were both present in 57.1% of operated vs. 3% of non-operated patients (P < 0.001). Oscillopsia with effort and with walking was found in 50% and 35.7% of operated patients, respectively, but none in the non-operated group (P < 0.001). Hearing tuning fork at malleolus and Valsalva and pneumatic speculum induced vertigo showed a statistically significant difference between the two groups (P = 0.003, P < 0.001, P = 0.010 respectively). Cervical vestibular-evoked myogenic potential (cVEMP) thresholds, air and bone conduction thresholds, and mean air-bone gap (ABG) were similar in the two populations (P > 0.05). The average dehiscence size was 4.7 mm (2.0 - 8.0 mm) and 3.8 mm (1.3 - 7.7 mm) in the operated and non-operated patients, respectively (P = 0.421).ConclusionsThe natures of cochleovestibular signs and symptoms were shown to be key factors in patients’ choice of a surgical management whereas paraclinical tests seem to be less significant in the patients’ decision for a surgical treatment.

Radiologic classification of superior canal dehiscence: implications for surgical repair.

Surgical access to repair a superior canal dehiscence (SCD) is influenced by the location of the bony defect and its relationship to surrounding tegmen topography as seen on computed tomography. There are currently no agreed-upon methods of characterizing these radiologic findings. We propose a formal radiologic classification system of SCD based on dehiscence location and adjacent tegmen topography. Retrospective case review Tertiary, neurotology referral center We identified 298 patients with superior canal dehiscence on CT from February 2001 to October 2013. Of these, 251 had symptomatic superior canal dehiscence syndrome and were included in the study. Patients underwent high-resolution temporal bone CT scans with creation of axial, coronal, Pöschl, and Stenver reformatted images to examine the superior semicircular canal. Two residents-in-training and a head and neck radiologist independently read the scans. CT scans were assessed for (1) superior canal dehiscence or "near" dehiscence, (2) defect location relative to the skull base, (3) surrounding tegmen defects, (4) geniculate ganglion dehiscence, (5) superior petrosal sinus-associated dehiscence (SPS), (6) low-lying tegmen, and (7) the distance between the outer table of the temporal bone and the arcuate eminence.

Three‐Dimensional Anatomic Analysis of Surgical Landmarks for Middle Fossa Approach

Objectives: The middle fossa approach needs the surgeon to have a 3-dimensional anatomic knowledge of internal auditory meatus (IAM), which is located underneath the middle fossa bony plate. Our purpose was to describe microsurgical anatomy of the middle fossa approach using temporal bone computed tomography (CT) 3-dimensional (3D) reconstruction. Methods: Thirty CT images of the temporal bone from patients aged between 20 and 60 years were selected. The inclusion criterion was a radiologically normal temporal bone CT scan. 3D-reconstructed images were obtained using high-resolution axial temporal bone CT scans. IAM, semicircular canal (SCC), cochlea, tympanic segment of the facial nerve (FN), geniculate ganglion (GG), and malleus were reconstructed. The length and angle among these structures was measured. Results: The mean lengths between the center of IAM and bony surface of middle cranial fossa at the Porus level was 7.7 mm (±1.0). The mean length between the superior of point of IAM of porus and GG was 15.4 mm (±1.5). The mean length between superior of point of IAM of porus and medial end of cochlear basal turn 9.9 mm (±0.9). Angle between the axis of SCC and the axis of tympanic segments of FN was 105.9° (±5.4). The mean angle between the axis of SCC and axis of IAM was 47.2° (±6.5) The mean angle between the axis of IAM and axis of tympanic segments of FN 59.6° (±10.9), The mean angle of 3-point malleus handle, GG, superior point of IAM of porus level was 113.8° (±9.8). Conclusions: The understanding of the 3D relationship in the microsurgical structure will help decide the drilling point for the IAM in case of lack of bony landmarks.

Middle Cranial Fossa Dehiscence as an Incidental Finding on CT

Objectives: Determine the prevalence of middle cranial fossa (MCF) dehiscence on computed tomography (CT) scans and establish its increase with age. Methods: All high-resolution temporal bone CT scans completed at a tertiary care center from 2011 to 2013, ordered by 1 otologist for any reason, were reviewed. Scans showing soft tissue, fluid, trauma, or previous operations were excluded. A total of 183 patients (296 ears) were reviewed blinded for age. The MCF floor was divided into 7 regions and systematically inspected. Ages of the patients were subsequently extracted from the medical record. Results: Logistic regression analysis confirmed increasing MCF dehiscence with age ( P &lt; .05, odds ratio [OR] 1.07, R = 0.584). Overall ages (1-88 years; average 38.5 years), 32% of MCF floors were dehiscent at any one site. For age 60 years and over, 55% were dehiscent. For 226 paired ears, if one ear was dehiscent, there was a 66% chance the other ear was dehiscent as well. Superior canal dehiscence (SCD) was seen in 7% of all patients, and only in combination with MCF dehiscence. SCD occurred in 16% of dehiscent ears. The most common sites were directly above the malleus head and above the additus ad antrum (36% and 28%, respectively). Conclusions: The incidence of MCF dehiscence increases with age. Over all ages, approximately 32% of ears show dehiscence. Over 60 years, approximately 55% show dehiscence. The increase of dehiscence with age is statistically significant. The most common sites along the MCF floor are in the epitympanum over the malleus head and additus ad antrum.

Radiological assessment of the sinus tympani: temporal bone HRCT analyses and surgically related findings.

To evaluate the morphology of the sinus tympani (ST) based on computed tomography (CT) scans (axial view), describing the findings in a cohort of 148 patients (296 ears), and classifying the prevalence according to our ST classification. To evaluate the surgical prevalence based on the type of ST. To calculate the sensibility and positive predictive value (PPV) of high-resolution computed tomography (HRCT) scans for ST involvement by cholesteatoma. Retrospective review of the radiologic database and surgical reports. In total, 98/296 (33.1%) middle ears presented a radiologic morphology Type A; 185/296 (62.5%) middle ears presented a radiologic morphology Type B; 13/296 (4.4%) middle ears presented a radiologic morphology Type C; HRCT showed a sensibility of 91%, specificity of 65%, PPV of 68% and negative predictive value (NPV) of 90%. ST shape and depth can influence surgical preference in cholesteatoma surgery. In the case of a shallower ST, an exclusive endoscopic exploration is chosen; whereas in the case of a deeper ST, a retrofacial approach is usually preferred. HRCT scans demonstrated high sensibility and NPV for ST involvement by cholesteatoma.

Three-dimensional Anatomical Analysis of Surgical Landmarks for the Middle Cranial Fossa Approach.

This study describes the microsurgical anatomy of the middle cranial fossa approach using temporal bone three-dimensional (3D) computed tomography (CT) reconstruction, which should contribute to determining the drilling point for the internal auditory meatus (IAM) when bony landmarks are absent. Thirty temporal bone CT scans were reviewed retrospectively. We measured the shortest and longest distances to IAM from the petrous ridge, and measured the angle between the facial nerve and various labyrinth structures. Three-dimensional reconstructed images were obtained using high-resolution axial temporal bone CT (0.7-mm-thick slices, FOV 90×90, KVp 120, 305mA, width 2,800, and level 800). The mean shortest and longest distances to IAM from the petrous ridge were 5.22 and 10.1mm, respectively. The mean distance to the IAM from the cochlea was 9.91mm. The mean angle between the IAM and superior semicircular canal was 47.21°, which was more acute than previously reported. The mean angle between the IAM and geniculate ganglion (GG) and external auditory canal was 113.8°, and the mean distance from the GG to the IAM was 15.44mm. Understanding the 3D relationships among the microsurgical structures will help to decide the drilling point for the IAM when bony landmarks are absent. A preoperative evaluation might be useful for preserving important neurovascular structures while approaching the middle fossa.

Superior Canal Dehiscence

Identify independent clinical and audiometric factors to predict a positive high-resolution computed tomography (HRCT) scan for superior canal dehiscence (SCD). Retrospective chart review. Tertiary referral center. Patients presenting SCD. Audiogram, VEMP, temporal bone HRCT, and SCD symptoms and signs chart. ABG, VEMP threshold, and symptoms and signs. Approximately 106 patients with SCD symptoms were included: 62 had a positive and 44 had a negative CT scan. The positive scan group showed a higher average of cochlear symptoms than the negative CT scan group (4.3 versus 2.6) (p < 0.001), but no statistical difference for vestibular symptoms (2.2 versus 1.8) was identified. CVEMP thresholds of the positive and negative CT scan groups were of 66 and 81 dB, respectively (p < 0.001). The positive CT scan group showed higher ABGs at 250 Hz (24 versus 14 dB) and 500 Hz (17 versus 8 dB) (p = 0.008 and p = 0.008, resectively). No statistical significance was found when comparing both groups for air and bone conduction thresholds. Approximately 23% of the positive CT scan group showed a Valsalva-induced vertigo against 2.3% of the negative scan group (p = 0.003); 27% of the positive CT scan group showed speculum-induced vertigo but none of the negative scan patients (p < 0.001). Using logistic regression, we found that each 10-dB unit increase in the 250 Hz ABG is associated to an increase odd of having SCD of 51% (OR, 1.51; 95% CI, 1.10-2.08). Nature and number of cochlear symptoms, Valsalva and pneumatic speculum-induced vertigo, VEMP thresholds, and ABGs seem to correlate with a positive HRCT. The ABG at 250 Hz is the most accurate predictor of SCD.

Imaging Prevalence of Sigmoid Sinus Dehiscence among Patients with and without Pulsatile Tinnitus

Define the radiographic prevalence of sigmoid sinus diverticulum or dehiscence (SSDD) in patients with and without pulsatile tinnitus (PT). Case series with chart review. Tertiary care university medical center. Patients imaged between January 1, 2003, and December 31, 2012. Two groups were evaluated for SSDD. The first ("PT") included patients whose radiology report indicated a clinical history of PT (n = 37 symptomatic ears in 30 patients). The second ("non-PT") included all patients undergoing temporal bone high resolution CT (HRCT) between November 2011 and November 2012 (n = 308 ears in 164 patients) for reasons other than pulsatile tinnitus. Primary outcome measure was the radiographic presence of SSDD. Covariates including age, gender, body mass index (BMI), and audiometric data were analyzed by independent t tests and Fisher's exact test. Within the PT group, SSDD was identified in 24% of ears (9/37) and 23% of patients (7/30); all SSDD patients were female (P = .024). Patients with SSDD were significantly younger (P = .037). SSDD more frequently caused objective tinnitus (P = .016). There was no difference in average BMI between those with and those without SSDD. In the non-PT group, SSDD was identified in 2 (both female) of 164 patients (1.2%; 0.6% of ears). The difference in SSDD prevalence between groups was significant (P < .0001). The prevalence of SSDD in patients with PT was 23%. Among patients with PT, those with SSDD were younger, exclusively female, and presented with objective tinnitus. The prevalence of SSDD among asymptomatic patients in 1 year was 1.2%.

The extent of inferior displacement of the mastoid tegmen is related to the severity of congenital aural atresia

Conclusion: The extent of inferior displacement of the mastoid tegmen is related to the severity of congenital aural atresia (CAA). Objective: To analyze anatomic variations observed on high-resolution temporal bone computed tomography (TBCT) in patients with CAA, the extent of inferior displacement of the mastoid tegmen and the size of the incudo-stapedial (IS) joint angle were compared with surgical parameters for atresiaplasty, such as Jahrsdoerfer score and hearing acuity. Methods: Sixty-one patients with unilateral CAA underwent high-resolution TBCT and hearing tests. We evaluated TBCTs in terms of Jahrsdoerfer criteria and analyzed the relationships among the inferior displacement of the mastoid tegmen, size of the IS joint angle, hearing acuity, and the Jahrsdoerfer score on the atretic side. Results: IS joint angle on the atretic side was found to be 120.6 ± 11°, which was significantly greater than the corresponding value of 103.4 ± 5.4° on the normal side. Cholesteatoma occurred significantly more often in CAA patients with narrow external auditory canals (EACs) (9/27; 33.3%), compared with CAA patients with no EAC opening (2/34; 5.9%). There was a significant relation between the extent of inferior displacement of the mastoid tegmen (28.9% in the atretic side and 17.3% in the normal side) and the Jahrsdoerfer score (p < 0.0001).