High-resolution Computed Tomography Temporal Bone Research Articles

Revisiting Correlation Between Pre Operative High Resolution Computed Tomography and Operative Findings in Attico Antral Disease.

(1) To correlate the findings of high resolution computed tomography (HRCT) scans with operative findings in chronic otitis media (attico antral disease). (2) To assess the role of HRCT in chronic otitis media (attico antral disease). This prospective observational study undertaken at a tertiary level teaching hospital included 50 patients of chronic otitis media (attico antral disease) who underwent pre-operative HRCT scanning and the findings were compared with the operative findings and correlation between the two was assessed with appropriate statistical methods. HRCT findings correlated well for the status of malleus and incus, facial nerve canal, lateral semicircular canal, and sinus plate but were less accurate for stapes and tegmen plate. As for disease extent and prediction of cholesteatoma the degree of correlation was site dependent being greater in mastoid air cell system and epitympanum and lesser in mesotympanum and hypotympanum. HRCT despite of its value in management of chronic otitis media has its drawbacks and limitations. CT's accuracy of prediction in some aspects of the disease varies with the site of pathology and this point must always be kept in mind by the operating surgeon. We suggest that each health care centre should establish their own correlative indices for HRCT temporal bone imaging in COM. HRCT cannot be entirely relied upon in management of chronic otitis media patients. However against the backdrop of improved radiological skills in interpreting temporal bone ct images, improved CT machines and importantly the growing concern over medicolegal issues, the role of pre operative CT scan in COM is much more than what was thought previously. Undoubtedly, it is a very useful 'aid' to management BUT a well-trained, experienced and alert surgeon is the key for an accurate diagnosis and successful management of chronic otitis media (attico-antral disease).

Vestibular evoked myogenic potential testing: Payment policy review for clinicians and payers.

A recent American Academy of Neurology Evidence-Based Practice Guideline on vestibular myogenic evoked potential (VEMP) testing has described superior canal dehiscence syndrome (SCDS) and evaluated the merits of VEMP in its diagnosis. SCDS is an uncommon but now well-recognized cause of dizziness and auditory symptoms. This article familiarizes health care providers with this syndrome and the utility and shortcomings of VEMP as a diagnostic test and also explores payment policies for VEMP. In carefully selected patients with documented history compatible with the SCDS, both high-resolution temporal bone CT scan and VEMP are valuable aids for diagnosis. Payers might be unfamiliar with both this syndrome and VEMP testing. It is important to raise awareness of VEMP and its possible indications and the rationale for coverage of VEMP testing. Payers may not be readily receptive to VEMP coverage if this test is used in an undifferentiated manner for all common vestibular and auditory symptoms.

An evaluation of preoperative high resolution computed tomography of temporal bone in cholesteatoma

<p class="abstract"><strong>Background:</strong> <span lang="EN-IN">Cholesteatoma is relatively common and potentially dangerous disease of the ear. It is characterised by local destruction and osseous erosion leading to complications. High resolution computed tomography (HRCT) is the imaging modality of choice for evaluation of middle ear structures and pathology. The aim of this study is to evaluate role of preoperative HRCT in the diagnosis of the disease, its extension and complications and plan for surgery.</span></p><p class="abstract"><strong>Methods:</strong> <span lang="EN-IN">This prospective study was conducted at a tertiary referral teaching hospital and 40 cases of cholesteatoma were selected and their pre-operative HRCT temporal bone findings and intraoperative findings were correlated. </span></p><p class="abstract"><strong>Results:</strong> <span lang="EN-IN">This study showed good correlation between preoperative HRCT findings of cholesteatoma, and intraoperative findings. </span></p><p class="abstract"><strong>Conclusions:</strong> <span lang="EN-IN">We conclude therefore the preoperative HRCT temporal bone is useful guide for the surgeon for the diagnosis and management of cholesteatoma.</span></p>

Is HRCT Temporal Bone Necessary in All Cases of Active Squamous Chronic Otitis Media?

To assess the usefulness of high resolution computed tomography (HRCT) temporal bones in cases of active squamous chronic otitis media (COM). Comparison of HRCT findings with operative findings. A prospective study of 104 clinically diagnosed patients with COM were included. Each patient was subjected to full clinical evaluation and HRCT temporal bone was done. Preoperative HRCT finding were correlated with surgical findings. The sensitivity of HRCT temporal bone in detecting cholesteatoma was 91.81%. However it could not differentiate cholesteatoma from other soft tissue density like granulation or hypertrophic mucosa or discharge, but soft tissue attenuation content with bone erosion was considered as hallmark of cholesteatoma. The sensitivity and specificity of HRCT for detecting malleus, incus and stapes erosion was 71.5 and 88.5%, 86.3 and 95% and 53.1 and 64.7% respectively. The sensitivity and specificity for detecting erosion of lateral semicircular canal (LSCC) was 77.78 and 98.2%. The sensitivity and specificity for facial canal was 80 and 100%. HRCT gives excellent details about the extent of cholesteatoma with reasonable accuracy in expert hands. It helps to warn the surgeon about anatomical variations preoperatively and detects complications if any. It effectively depicts integrity or erosion of dural plate, sinus plate, LSCC, facial nerve. Malleus and incus are seen reasonably well but status of stapes are not recorded effectively.

Preoperative evaluation of cochlear implantation through the round window membrane in the facial recess using high-resolution computed tomography.

We evaluated the risk of cochlear implantation through the round window membrane in the facial recess through a preoperative analysis of the angle between the facial nerve-round window and the cranial midline using high-resolution temporal bone CT. Temporal bone CT films of 176 patients with profound sensorineural hearing loss at our hospital from 2013 to 2015 were reviewed. The preoperative temporal bone CT scans of the patients were retrospectively analysed. The vertical distance (d value) from the leading edge of the facial nerve to the posterior wall of the external auditory canal and the angle (α value) between the line from the leading edge of the facial nerve to the midpoint of the round window membrane and the median sagittal line on the round window membrane plane were measured. Based on intraoperative observation, the round window membrane was divided into complete round window membrane exposure (group A), partial exposure (group B), and unexposed (group C) groups, and statistical analysis was performed. The α value could be effectively measured for all 176 patients (62.60 ± 7.12), and the d value could be effectively measured for 95 cases (5.53 ± 1.00). An analysis of the correlation between the α and d values of these 95 cases found a negative correlation. Of the 176 cases, one-way analysis of variance (ANOVA) showed that the differences among the groups were significant [P = 0.000 (< 0.05)]. The angle (α value) between the line connecting the leading edge of the facial nerve to the midpoint of the round window and the median sagittal line measured in preoperative CT scans was associated with the difficulty of intraoperatively exposing the round window membrane. When the α value was larger than a certain degree, the difficulty of exposing the round window membrane was increased. In such cases, the surgeon should fully expose the round window membrane during surgery, which could result decrease the likelihood of complications.

Measuring cochlear duct length in Asian population: worth giving a thought!

The anatomy of the cochlea forms the basis for a successful cochlear implantation. Cochlear duct length (CDL) is defined as the length of the scala media as measured from the middle of the round window to helicotrema. Preoperative measurement of CDL is particularly important when precise intracochlear electrode array placement is desired. It can be done both histologically and radiologically. Preoperative high-resolution computed tomography (HRCT) scan which forms an integral part of cochlear implant workup is a useful tool to calculate CDL using 3D reconstructions. This study was done in SMS Medical College and Hospital, Jaipur, India, which is a tertiary care hospital and referral centre for cochlear implants. HRCT temporal bones of all children less than 6years of age, with congenital bilateral severe-to-profound SNHL who were being worked up for cochlear implant were studied and analysed. 124 patients (56 females and 68 males) with hearing loss were evaluated for cochlear implantation. HRCT temporal bone of these patients was analysed and a variable A was measured which is defined as the linear measurement from the round window to the farthest point on the opposite wall of the cochlea on a reformatted CT scan slice. Mean of distance A for right ear of these patients was 8.10mm (range 7.7-9.2mm). Mean for the same in left ear of these patients was 8.14mm (range 7.7-9.0mm), giving an overall average of 8.12mm. Using the formula, CDL = 4.16A-3.98, we calculated the length of cochlear duct. Mean cochlear duct length was 29.8mm with a range from 28 to 34.3mm. To the best of our knowledge, this is the first large sample study of cochlear length in population of this part of the world. A smaller cochlear length in this part of the world as compared to the Caucasian cochlear duct is a significant finding in understanding of the cochlear anatomy and physiology. It would also have great implications on the insertion depth in cochlear implantation.

High resolution computed tomography of temporal bone in the evaluation of otologic diseases

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; &lt;span lang="EN-IN"&gt;Conventional radiological methods like X-ray mastoid have limited ability to delineate the details of the complex temporal bone and cochlea-vestibular anatomy and disease pathology. This can be overcome by the use of High resolution computed tomography (HRCT) evaluation of the temporal bone. HRCT is helpful in evaluating the anatomy and pathology type and extent of disease, thereby helps in preoperative planning. &lt;/span&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; &lt;span lang="EN-IN"&gt;The CT scan of forty five patients attending the outpatient department of otorhinolaryngology in a tertiary care centre between August 2014 to August 2017 was evaluated in this study. Each CT scan was interpreted by an otolaryngologist and a radiologist and interpretation was by consensus. The data collected was evaluated and results are reported as rates and proportions (%). &lt;/span&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; &lt;span lang="EN-IN"&gt;The study evaluated CT scan of 45 patients of which 35 were male patients and 10 were female patients with age ranging from 5 years to 75 years. Most of these patients belonged to the 21-30, 31-40 age groups [9 (20%) in each group]. Infections of middle ear cleft (all with cholesteatoma), fractures of the temporal bone, anomalies and tumors of the external auditory canal and middle ear were the pathologies observed in these CT scans with infection (otomastoiditis) [23 (51.1%)] being the most common pathology observed. &lt;/span&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; &lt;span lang="EN-IN"&gt;Pre-operative CT scan may not only help in identifying the nature, extent of infectious disease including ossicular, bony erosions; it may also identify anomalies in the temporal bone and surrounding structures. Thus, HRCT temporal bone will help the surgeon in planning effective surgical strategy, reducing morbidity during the surgery.&lt;/span&gt;&lt;/p&gt;

Reliability of temporal bone high-resolution CT in patients with facial paralysis in temporal bone fracture

ObjectiveThis study aimed to investigate the reliability of temporal bone high-resolution CT (HRCT) in patients with traumatic facial paralysis. MethodsHRCT with cross-sectional scanning and multi-planar reformation (MPR) was performed on 26 cases with traumatic facial paralysis, and the preoperative imaging manifestations were compared with surgical findings. ResultsPreoperative HRCT revealed fallopian canal damage at the posterior genu in 1 case, geniculate ganglion in 22 cases, labyrinthine segment in 4 cases, tympanic segment in 13 cases and mastoid segment in 0 case, while surgical findings confirmed fallopian canal damage at the posterior genu in 7 cases, geniculate ganglion in 23 cases, labyrinthine segment in 4 cases, tympanic segment in 17 cases and mastoid segment in 7 cases. The accuracy of temporal bone HRCT in revealing damage at those segments of fallopian canal was 14.3%, 95.7%, 100%, 76.5, and 0%, respectively. ConclusionTemporal bone HRCT can generally estimate the extent of damage and provide important information for traumatic facial paralysis before surgery. However, it is unreliable in revealing the damage of fallopian canal at the posterior genu and mastoid segment.

Analysis of clinical characteristic of the middle ear malformation with cholesteatoma

Objective To discuss the clinical characteristic of middle ear malformation with cholesteatoma. Methods From September, 2011 to November, 2016, 23 cases of middle ear malformation with cholesteatoma were collected. Their symptoms, ENT examination, temporal bone high resolution computed tomography (HRCT) and intra-operative findings were analyzed. Results All 23 patients had hearing loss. 90.0% patients had ear discharge and tin-nitus. 86.96% patients had perforation in pars flaccida of tympanic membrane. 95.7% patients had poor mastoid gasification. 73.9% patients had undeveloped or dysplastic tympanic antrum. 100% patients had destruction of the ossicular chain. 56.5% patients had malformation of the ossicular chain. 52.2% patients had exposed facial nerve. 30.4% patients had hyperplasia of the attic bone. Conclusion The symptoms and physical examinations of middle ear malformation with cholesteatoma are the same as middle ear cholesteatoma. Poor mastoid gasification can usually be detected on temporal bone HRCT. The most common malformation is dysplastic tympanic antrum, followed by malformation of the ossicular chain, exposed facial nerve and hyperplasia of the attic bone. Temporal bone HRCT can indicate the mal-formation and destruction quite well. Key words: Middle ear malformation; Cholesteatoma; Temporal bone; High resolution computed tomography (HRCT)

Prediction of round window visibility in cochlear implantation with temporal bone high resolution computed tomography

Objective: To discuss the prediction of round window(RW) visibility in cochlear implantation(CI) with temporal bone high resolution computed tomography(HRCT). Methods: From January 2013 to January 2017, 130 cases underwent both HRCT and CI in our hospital were analyzed. The distance from facial nerve to posterior canal wall(FWD), the angle between facial nerve and inner margin of round window(FRA), and the angle between facial nerve and tympanic anulus to inner margin of round window(FRAA) were detected at the level of round window on axial temporal bone HRCT. A line parallel to the posterior wall of ear canal was drawn from the anterior wall of facial nerve at the level of round window on axial temporal bone HRCT and its relationship with round window was detected (facial-round window line, FRL): type0-posterior to the round window, type1-between the round window, type2-anterior to the round window. Their(FWD, FRA, FRAA, FRL) relationships with intra-operative round window visibility were analyzed by SPSS 17.0 software. Results: FWD(F=18.76, P=0.00), FRA(F=34.57, P=0.00), FRAA (F=14.24, P=0.00) could affect the intra-operative RW visibility significantly. RW could be exposed completely during CI when preoperative HRCT showing type0 FRL. RW might be partly exposed and not exposed when preoperative HRCT showing type1 and type2 FRL respectively. Conclusion: FWD, FRA, FRAA and FRL of temporal bone HRCT can predict intra-operative round window visibility effectively in CI surgery.

CT and MR Imaging of the Pediatric Temporal Bone: Normal Variants and Pitfalls

This article will discuss high-resolution CT (HRCT) and MRI of the pediatric temporal bone with a focus on variant anatomy that can mimic pathology or affect surgical planning, as well as some potential pitfalls in image interpretation. The latest research shows that with improving imaging technology, there is better visualization of temporal bone structure, both normal and abnormal, on HRCT and MRI. Examples include earlier detection of cochlear obstruction in labyrinthitis ossificans with MRI, the ability to better define ossicular chain abnormalities, and the identification of pericochlear lucency in children without hearing loss. Advances in temporal bone imaging have contributed to a greater understanding of normal anatomy as well as temporal bone pathology and its implications for treatment and surgical planning. It is clear that correlation of imaging findings with clinical and surgical findings will be an essential part of future research.

Measurement of cochlear length using the ‘A' value for cochlea basal diameter: A feasibility study

Objectives: To determine whether the cochlea basal diameter (A value) measurement can be consistently and precisely obtained from high-resolution temporal bone imaging for use in cochlear length estimation.Methods: A feasibility study at a tertiary referral center was performed using the temporal bone CTs of 40 consecutive patients. The distance from the round window to the lateral wall was measured for each cochlea by two independent reviewers, a neuroradiologist and an otolaryngologist. The interrater reliability was calculated using the intraclass correlation coefficient (ICC) and the Bland–Altman plot.Results: Forty patients (19 males, 21 females) for a total of 80 cochleae were included. Interrater reliability on the same ear had a high level of agreement by both the ICC and the Bland–Altman plot. ICCs were 0.90 (95% CI: 0.82, 0.94) for the left ear and 0.96 (95% CI: 0.92, 0.98) for the right ear. Bland–Altman plot confirmed interrater reliability with all 96% of measurements falling within the 95% limits of agreement.Conclusions: Measurement between the round window and lateral cochlear wall can be consistently and reliably obtained from high-resolution temporal bone CT scans. Thus, it is feasible to utilize this method to estimate the cochlear length of patients undergoing cochlear implantation.

When to operate facial nerve schwannomas?

Facial nerve schwannomas are rare, benign slow-growing tumors arising from the Schwann cell sheath of the facial nerve. A 60-year-old female presented with a mass in the left parotid region for 6 months. It was associated with Grade 6 left lower motor neuron facial palsy. Malignancy of the parotid gland associated with facial nerve involvement was suspected. However, high-resolution computed tomography temporal bone and magnetic resonance imaging done showed a soft-tissue density along the vertical portion of the facial nerve and into the parotid gland. The lesion was eroding the skull base and was found to be in direct contact with the jugular bulb. She underwent excision of the tumor by a modified Blair incision along with a cortical mastoidectomy. Tumor abutting the jugular bulb was removed through transmastoid approach. Facial nerve was transected during tumor excision. Postoperatively, gold implant was inserted. Facial schwannomas can arise from any segment of the nerve, from the cerebellopontine angle to the extratemporal peripheral portion. About 650 cases have been reported in the world literature. The best timing for surgery depends on facial and hearing function, size, and intracranial mass effect.

Radiological changes in anatomy of temporal bone in cases of unsafe chronic suppurative otitis media: A retrospective study

Introduction: The ability of high-resolution computed tomography (HRCT) to depict the status of structure of the temporal bone represents a major advance in delineating pathology before surgical exploration of ear in cases of unsafe chronic suppurative otitis media (CSOM) or cholesteatoma. Aims and Objectives: The aim of this study was to evaluate the role of HRCT temporal bone in cases of unsafe CSOM and to assess the erosion of various structures in middle ear cleft. Study Design: This was a retrospective analysis. Materials and Methods: Fifty HRCT scans of temporal bone of the patients who were diagnosed as case of unsafe CSOM were selected and analyzed retrospectively. Criterion for inclusion was CSOM with cholesteatoma or granulations or polyp or posterior canal wall sagging or foul smelling discharge. In HRCT scans, 1 mm thickness sections were studied in both axial and coronal planes. Criterion for exclusion was history of previous ear surgery, history suggestive of head injury or skull base trauma in the past or known cases of temporal bone neoplastic pathology. Results: Maximum number of patients belonged to the age group of 21–30 years. Ossicular erosion was the most common (90%) finding followed by scutum erosion (84%). Erosion of sigmoid sinus plate was seen in only one case (2%). Cochlear promontory fistula was seen in none of the computed tomography scans. In ossicular chain, incus was the most common ossicle to be necrosed (92%) followed by malleus (66%). Conclusion: HRCT temporal bone delineates the location and extent of the disease and provides information on anatomical variations and complications.

CDH23 Related Hearing Loss: A New Genetic Risk Factor for Semicircular Canal Dehiscence?

To investigate the prevalence and relative risk of semicircular canal dehiscence (SCD) in pediatric patients with CDH23 pathogenic variants (Usher syndrome or non-syndromic deafness) compared with age-matched controls. Retrospective cohort study. Multi-institutional study. Pediatric patients (ages 0-5 years) were compared based on the presence of biallelic pathogenic variants in CDH23 with pediatric controls who underwent computed tomography (CT) temporal bone scan for alternative purposes. Retrospective review of diagnostic high resolution CT temporal bone scans and magnetic resonance imaging (MRI) for evaluation of SCD. Superior and posterior semicircular canals were evaluated by a neuroradiologist for presence of SCD or abnormal development. Forty-two CT scans were reviewed for SCD. Eighty-six percent of the CDH23 variant group had abnormalities in at least one canal compared with only 12% in age-matched controls. In the CDH23 variant group there were four patients with superior SCD (57%, RR = 10.0) and three patients with posterior canal abnormalities (43%, RR = 7.5) compared with two, and two patients, respectively, in the control population. Four CDH23 variant children had bilateral abnormalities. One child had thinning or dehiscence in both the superior and posterior canals. Relative risk of SCD in children with CDH23 pathogenic variants is 7.5 (p < 0.001) compared with the pediatric control population. Children with a CDH23 pathogenic variants are at significantly increased risk of having SCD and this may be a contributing factor to the vestibular dysfunction in Usher syndrome type 1D patient population.

Novel compound heterozygous mutations in SLC26A4 gene in a Chinese Han family with enlarged vestibular aqueduct

ObjectiveTo identify the disease-related SLC26A4 mutants in a Chinese Han pedigree associated with Enlarged vestibular aqueduct (EVA). MethodsEVA diagnosis was based on the family history, clinical examinations, systematically audiometric evaluations, high-resolution computed tomography (HRCT) of the temporal bone, and magnetic resonance imaging (MRI) of inner ear. Sanger sequencing and mutation analysis of the SLC26A4 gene were performed in all members of this family to identify the disease-related SLC26A4 mutants. Mutations in the SLC26A4 gene were compared with 200 ethnically matched control persons to exclude common polymorphism. ResultsAll members in this family were negative for systemic and thyroid diseases. There were three subjects (I-2, II-2 and II-3) with bilateral sensorineural deafness since childhood. Temporal bone HRCT scans and inner ear MRI showed bilateral enlarged vestibular aqueduct with Mondini malformation in II-2 and II-3. A novel SLC26A4 splice-site mutation c.1001 + 5G > C was identified in compound heterozygosity with the mutation c.919-2A > G in the proband and in II-2. This novel compound heterozygote of two splice site mutations was not found in 200 normal hearing Chinese Han controls. ConclusionsA novel splice site mutation of c.1001 + 5G > C was identified, and the novel compound heterozygote of two splice site mutations, c.1001 + 5G > C and c.919-2A > G, in the SLC26A4 gene has been linked to hearing impairment in EVA patients.

A radiological study of frontal sinus in adult south Indian population

The adult petromastoid canal (PMC) is a thin anatomical structure, but in young children, it can be wide on high resolution CT (HRCT) scans. We performed this study to evaluate the year-by-year change in width and shape of the PMC in the young child.We retrospectively reviewed temporal bone HRCT scans, performed between 2007 and 2012. Eighty children were included (age range: 0.3–6.9 years; median age: 3.1 years; 56% male). All scans had a slice thickness of ≤1 mm.The average width of the PMC was 1.95 mm in children <2 years, compared to 0.83 mm in children ≥2 (p < 0.001). We categorized the PMC into 4 subtypes. A bulky (type III) PMC was predominant <2 years. A thin curvilinear (type I) PMC was more prevalent in the older children. Type II and IV PMC were found infrequently. The PMC width correlated inversely with the degree of pericapsular ossification (p < 0.001), and mastoid pneumatisation (p < 0.001).A wide PMC (≥1 mm) is a common finding in children <2 years. As children grow older, the PMC progressively narrows. This correlates to increased temporal bone pneumatisation and ossification of the otic capsule.

Association between nasal septal deviation and pneumatisation of mastoid air cells: A computerised tomographic study

The adult petromastoid canal (PMC) is a thin anatomical structure, but in young children, it can be wide on high resolution CT (HRCT) scans. We performed this study to evaluate the year-by-year change in width and shape of the PMC in the young child.We retrospectively reviewed temporal bone HRCT scans, performed between 2007 and 2012. Eighty children were included (age range: 0.3–6.9 years; median age: 3.1 years; 56% male). All scans had a slice thickness of ≤1 mm.The average width of the PMC was 1.95 mm in children <2 years, compared to 0.83 mm in children ≥2 (p < 0.001). We categorized the PMC into 4 subtypes. A bulky (type III) PMC was predominant <2 years. A thin curvilinear (type I) PMC was more prevalent in the older children. Type II and IV PMC were found infrequently. The PMC width correlated inversely with the degree of pericapsular ossification (p < 0.001), and mastoid pneumatisation (p < 0.001).A wide PMC (≥1 mm) is a common finding in children <2 years. As children grow older, the PMC progressively narrows. This correlates to increased temporal bone pneumatisation and ossification of the otic capsule.

Middle Cranial Fossa Dehiscence as an Incidental Finding on CT.

This retrospective chart review demonstrates that the prevalence of middle cranial fossa (MCF) dehiscence on computed tomography (CT) scans increases with age. High-resolution temporal bone CT scans, which had been obtained for any otologic complaint, were reviewed independent of all clinical history. Scans showing soft tissue, fluid, trauma, or previous operations were excluded. The CTs from 183 patients (296 ears) were reviewed, blinded for age and body mass index (BMI). The MCF floor was divided into 7 regions and systematically inspected. Ages and BMIs of the patients were subsequently extracted from the medical record. Logistic regression analysis confirmed increasing MCF dehiscence with age (P < .05, odds ratio [OR] = 1.07, R = .584). Over all ages (range, 1-88 years; average, 38.5), 32% of MCF floors were dehiscent at any 1 site. For age 60 and over, 55% were dehiscent. The most common sites of MCF dehisence were directly above the malleus head and above the additus ad antrum (35% and 28%, respectively). Superior canal dehiscence (SCD) was seen in 7% of all patients and only in the context of MCF dehiscence. The prevalence of MCF dehiscence increased with age when patients were analyzed by BMI <25, BMI = 25-30, and BMI >30 (P < .003, P < .04, P = .03). The increase of middle cranial fossa dehiscence with respect to age is statistically significant. Over all ages, approximately 32% of ears show dehiscence. Over 60 years, approximately 55% show dehiscence. The odds of having dehiscence double with a 10-year difference in age. The most common sites along the MCF floor are in the epitympanum over the malleus head and the additus ad antrum. There was a statistically significant increase in MCF dehiscence with age when patients with equivalent BMIs are compared.

Congenital Oval Window Aplasia: An Unusual Cause of Conductive Hearing Loss in an Adult

Objective: To report a case of congenital oval window aplasia (COWA) in a Filipino adult presenting with unilateral maximal conductive hearing loss and discuss the diagnostic considerations, pathophysiology and management.&#x0D; Methods:&#x0D; Study Design: Case report&#x0D; Subjects: One (1)&#x0D; Setting: Tertiary Public Referral Center&#x0D; Results: Audiometric evaluation showed a maximal unilateral left conductive hearing loss. High resolution temporal bone CT showed absence of the oval window on the left along with facial and stapes abnormalities. Exploratory tympanotomy showed an aberrant facial nerve, monopodal and abnormally located stapes and absent oval window. Postoperative hearing gain achieved after a neo-oval window and Schuknecht piston wire prosthesis remained stable over two years.&#x0D; Conclusion: A congenital minor ear anomaly classified as Cremers Class 4a in which a congenital oval window aplasia was associated with an aberrant facial nerve anomaly and a monopodal stapes is reported. Recent literature supported the view that congenital oval window aplasia can in selected cases be amenable to various surgical approaches and a stable postoperative hearing gain is achievable in the long term.&#x0D; Keywords: oval window absence, Cremers classification, congenital middle ear