Evaluation of subarcuate canal on CT images in the perspective of clinical basis.

OBJECTIVES: The aim of our study to contribute to the field of morphometrics by including measurements of the SAC and SAF and their distances from surrounding structures, particularly for surgeons involved in retrosigmoid approach for internal acoustic meatus tumor surgery and cerebellopontine angle surgery. Although there is limited information in the literature regarding the role of the subarcuate fossa (SAF) and subarcuate canal (SAC), it has been suggested that the SAC may be a potential pathway for infection from the middle ear to the posterior cranial fossa, and cerebellar abscesses may have this origin. METHODS: For the images of our study, computerized tomography images of 118 individuals (59 females and 59 males) between the ages of 18-65 who applied to Bayindir Health Group. RESULTS: The width of the cranial opening of the subarcuate canal was determined as 44 ± 0.54 mm, width of the labyrinth opening of the subarcuate canal was determined as 60 ± 0.42 mm, Length of the subarcuate canal was determined as 8.79 ± 2.31 mm, width of the subarcuate canal was determined as 5.54 ± 1.75 mm, and depth of subarcuate fossa was determined as 1.67 ± 0.69 mm. The distance of the cranial opening of the subarcuate canal to the superior semicircular canal (SSC-SAC/C) was measured as 5.33 ± 1.81 mm, The distance of the labyrinth opening of the subarcuate canal to the superior semicircular canal (SSC-SAC/L) was measured as 3.90 ± .98 mm, length of the petrous part of the temporal bone medial to the anterior semicircular canal measured from the apex to the SSCD (PLM) was measured as 33.56 ± 0.42 mm. No statistically significant differences were found between the right and left sides. CONCLUSIONS: The morphometric measurements obtained in this study can provide useful information for neurosurgeons, neurotologist and otolaryngologists involved in retrosigmoid approach for internal acoustic meatus tumor surgery and cerebellopontine angle surgery, and for patients undergoing cochlear implant planning with a retrofacial approach.

Vestibular hydrops in patients with semicircular canal malformation.

OBJECTIVE: To investigate the vestibular endolymphatic hydrops in patients with semicircular canal malformation. METHODS: We searched 7864 patients who underwent MR Imaging after contrast injection and found 21 patients with semicircular canal malformations. Another 9 non-malformed patients with unilateral hearing loss were randomly included. We asked patients about their medical history and measured the volume of total vestibular fluid space and endolymphatic space. The vestibular volume ratio = endolymphatic space/total fluid space × 100. RESULTS: Hearing loss was observed in 18 of 30 malformed ears and in 7 of 12 non-malformed ears. Statistical analysis showed no association between semicircular canal malformation and hearing loss. In the semicircular canal malformation group, the average vestibular volume ratio (22.6%) in the ears with hearing loss was higher than that in the ears without hearing loss (11.4%). There was no statistically significant difference in the average vestibular %EL in ears with hearing loss between the malformed inner ear group (22.6%) and non-malformed group (28.2%) (P>0.05). CONCLUSION: There was no correlation between semicircular canal malformation and hearing loss. The mean vestibular hydrops volume ratio of the semicircular canal deformed ears with hearing loss was about 22.6%, which was not different from that of normal ears.

Research on congenital severe-to-profound sensorineural hearing loss associated with central lucency of the bony island of the lateral semicircular canal.

BACKGROUND: Central lucency of the bony island of the lateral semicircular canal (LSCC) is commonly found in patients with congenital severe-to-profound sensorineural hearing loss (SNHL). OBJECTIVE: Exploring the significance of bony island lucency of LSCC in congenital severe-to-profound SNHL patients. MATERIAL AND METHODS: Retrospective measurements of the inner ear structures were made on axial temporal bone CT scans from 182 (364 ears) congenital severe-to-profound SNHL patients and 50 (100 ears) tympanic membrane perforation (TMP) patients. RESULTS: The incidence of bony island lucency of LSCC was 46.7% in the congenital severe-to-profound SNHL group and 0% in the TMP group. There was a statistically significant difference in inner ear structures among congenital severe-to-profound SNHL patients with normal inner ear structure and bony island lucency of LSCC, congenital severe-to-profound SNHL patients with normal inner ear structure and no bony island lucency of LSCC, and TMP patients. The importance of the bony island lucency of LSCC was further confirmed through multiple linear regression analysis. CONCLUSIONS AND SIGNIFICANCE: Bony island lucency may have significance in congenital severe-to-profound SNHL and may be a manifestation of largely overlooked SCC malformation or hypoplasia of the inner ear.

Association of Ear Anomalies and Hearing Loss Among Children With 22q11.2 Deletion Syndrome.

OBJECTIVE: To identify inner and middle ear anomalies in children with 22q11.2 deletion syndrome (22q11DS) and determine associations with hearing thresholds. STUDY DESIGN: Retrospective study. SETTING: Two tertiary care academic centers. METHODS: Children presenting with 22q11DS between 2010 and 2020 were included. Temporal bone imaging with computed tomography or magnetic resonance imaging was reviewed by 2 neuroradiologists. RESULTS: Twenty-two patients (12 female, 10 male) were identified. Forty-four ears were evaluated on imaging. There were 15 (34%) ears with abnormal semicircular canals, 14 (32%) with abnormal vestibules, 8 (18%) with abnormal ossicles, 6 (14%) with enlarged vestibular aqueducts, 4 (9.1%) with abnormal facial nerve canals, and 4 (9.1%) with cochlear anomalies. There were 25 ears with imaging and audiometric data. The median pure tone average (PTA) for ears with any structural abnormality was 41.0 dB, as compared with 28.5 dB for ears without any structural abnormality (P = .21). Of 23 ears with normal imaging, 6 (26%) had hearing loss in comparison with 13 (62%) of 21 ears with abnormalities (P = .02). Total number of anomalies per ear was positively correlated with PTA (Pearson correlation coefficient, R = 0.479, P = .01). PTA was significantly higher in patients with facial nerve canal anomalies (P = .002), vestibular aqueduct anomalies (P = .05), and vestibule anomalies (P = .02). CONCLUSIONS: Semicircular canal, ossicular, vestibular aqueduct, and vestibular anomalies were detected in children with 22q11DS, especially in the setting of hearing loss. Careful evaluation of anatomic anomalies is needed prior to surgical intervention in these patients.

Comparison of vestibular ocular reflex and gross motor development in children with semicircular canal aplasia and hypoplasia.

OBJECTIVE: To examine the effect of vestibular ocular reflex on gross motor development in children with semicircular canal aplasia and hypoplasia. STUDY DESIGN: Case series. MATERIALS AND METHODS: Children with congenital hearing loss underwent temporal bone computed tomography to assess their inner ear morphology. In this study, we examined eight children with bilateral complete aplasia of semicircular canals and seven children with bilateral hypoplasia of semicircular canals. Their vestibular ocular reflex was assessed using a damped rotational chair test. Their gross motor development was assessed by examining their ages of acquisition of head control and independent walking. RESULTS: All eight children with semicircular canal aplasia were diagnosed as having CHARGE syndrome and five children were found to have CHD7 mutations. Cochlear morphological examination showed that cochlear hypoplasia type III was the most common in eight of 16 ears in children with semicircular canal aplasia. In semicircular canal hypoplasia, incomplete partition type II was found in seven of 14 ears. All eight children with semicircular canal aplasia showed no response in the damped rotational chair test. Even the three children followed up were unresponsive in all tests. In the group with semicircular canal hypoplasia, three children showed normal responses, one child showed no response, and three children showed poor responses. The mean age of acquisition of head control was 9.1 ± 6.3 months and that of independent walking was 31 ± 8.1 months in children with semicircular canal aplasia. The mean age of acquisition of head control was 6.0 ± 2.8 months and that of independent walking was 19.9 ± 4.9 months in children with semicircular canal hypoplasia. CONCLUSIONS: We found that children with semicircular canal aplasia have severe dysfunction of the vestibular ocular reflex, and vestibular sensory cells derived from the semicircular canal may not be present. Semicircular canal hypoplasia is associated with dysfunction of the vestibular ocular reflex, but vestibular sensory cells may be present, and rotary nystagmus develops with growth similar to that observed in normal children previously reported. Semicircular canal aplasia is associated with CHARGE syndrome, and affected children tended to have a slower gross motor development. It was suggested that the combination of visual impairment and mental retardation may delay the development of central-level integrated functions and may further delay motor development.

Congenital Inner Ear Abnormalities and COVID-19-Related Ear Infections.

Congenital deformities of the labyrinth of the inner ear may be associated with an increased risk of infection and varying degrees of otologic and vestibular dysfunction. Lateral semicircular canal abnormalities specifically can be associated with either normal hearing or hearing loss (conductive or sensorineural). In our patient, the acute symptoms of vertigo and tinnitus coincided with the diagnosis of COVID-19. It is unlikely that the symptomatology was related to the acute infection, even in the face of the underlying congenital abnormality. It has been shown that there is no correlation between the severity of the radiological abnormality and vestibular symptomatology in patients with isolated abnormalities of the semicircular canals. The abnormality can be asymptomatic.

Nystagmus in patients with lateral semicircular canal dysplasia.

BACKGROUND: Dizziness is not a common symptom in the lateral semicircular canal (LSCC) dysplasia, and nystagmus findings has been rarely described in LSCC dysplasia. OBJECTIVE: To investigate the characteristics of spontaneous and positional nystagmus in patients with LSCC dysplasia. METHODS: Patterns of spontaneous and positional nystagmus of twelve patients with LSCC dysplasia, who visited our clinic with a chief complaint of dizziness, were investigated. RESULTS: LSCC dysplasia was observed unilaterally in 4, and bilaterally in 8 patients. Non-rotatory dizziness with various onset times was the most common description of dizziness, and unilateral caloric weakness was observed in 82% of patients. Direction-fixed nystagmus, in which the direction of spontaneous nystagmus was same with that of positional nystagmus, was observed in 9 patients, and direction-changing positional nystagmus, in which the direction of nystagmus was changed from that of spontaneous nystagmus by positioning maneuvers, was observed in 3 patients, of whom down-beating or direction-changing spontaneous nystagmus was observed in one patient each. CONCLUSION: While direction-fixed horizontal nystagmus is the most commonly observed type of nystagmus in LSCC dysplasia, atypical spontaneous nystagmus, such as down-beating nystagmus or direction-changing spontaneous nystagmus, may be observed in patients with bilateral LSCC dysplasia.

New Classification of Cochlear Hypoplasia Type Malformation: Relevance in Cochlear Implantation.

OBJECTIVES: This paper attempts to create a new classification type of cochlear hypoplasia (CH)-type malformation taking into consideration of vestibular section and internal auditory canal (IAC). MATERIALS AND METHODS: Preoperative computed-tomography (CT) scans of cochlear implant (CI) candidates (N=31) from various clinics across the world with CH type malformation were taken for analysis. CT dataset were loaded into 3D-slicer freeware for three-dimensional (3D) segmentation of the inner-ear by capturing complete inner-ear structures from the entire dataset. Cochlear size in terms of diameter of available cochlear basal turn and length of cochlear lumen was measured from the dataset. In addition, structural connection between IAC and cochlear portions was scrutinized, which is highly relevant to the proposed CH classification in this study. RESULTS: CH group-I has the normal presence of IAC leading to cochlear and vestibular portions, whereas CH group-II is like CH group-I but with some degree of disruption in vestibular portion. In CH group-III, a disconnection between IAC and the cochlear portion irrespective of other features. Within all these three CH groups, the basal turn diameter varied between 3.1 mm and 9.6 mm, and the corresponding cochlear lumen length varied between 3 mm and 21 mm for the CI electrode array placement. CONCLUSION: A new classification of CH mainly based on the IAC connecting the cochlear and vestibular portions is presented in this study. CI electrode array length could be selected based on the length of the cochlear lumen, which can be observed from the 3D image.

Cochlear nerve canal stenosis and associated semicircular canal abnormalities in paediatric sensorineural hearing loss: a single centre study.

OBJECTIVE: This study aimed to evaluate the association between cochlear nerve canal dimensions and semicircular canal abnormalities and to determine the distribution of bony labyrinth anomalies in patients with cochlear nerve canal stenosis. METHOD: This was a retrospective study in which high-resolution computed tomography images of paediatric patients with severe-to-profound sensorineural hearing loss were reviewed. A cochlear nerve canal diameter of 1.5 mm or less in the axial plane was classified as stenotic. Semicircular canals and other bony labyrinth morphology and abnormality were evaluated. RESULTS: Cochlear nerve canal stenosis was detected in 65 out of 265 ears (24 per cent). Of the 65 ears, 17 ears had abnormal semicircular canals (26 per cent). Significant correlation was demonstrated between cochlear nerve canal stenosis and semicircular canal abnormalities (p < 0.01). Incomplete partition type II was the most common accompanying abnormality of cochlear nerve canal stenosis (15 out of 65, 23 per cent). CONCLUSION: Cochlear nerve canal stenosis is statistically associated with semicircular canal abnormalities. Whenever a cochlear nerve canal stenosis is present in a patient with sensorineural hearing loss, the semicircular canal should be scrutinised for presence of abnormalities.

Bilateral superior semicircular canal dehiscence: bilateral conductive hearing loss with subtle vestibular symptoms.

Superior semicircular canal dehiscence is caused by a bone defect on the roof of the superior semicircular canal. The estimated prevalence when unilateral varies between 0.4% and 0.7% and is still unknown when bilateral. Patients may present with audiologic and vestibular symptoms that may vary from asymptomatic to disabling. We report a case of a 72-year-old Caucasian woman presented to otolaryngology department reporting imbalance, bilateral pulsatile tinnitus, hypoacusis while being very sensitive to certain sounds. Physical examination was unremarkable, except for the Rinne test that was negative in both sides. The patient underwent an audiometry revealing a mild bilateral conductive hearing loss. A temporal bone CT scan was performed which evidenced bilateral superior semicircular canal dehiscence. Cervical vestibular evoked myogenic potentials and electrocochleography confirmed diagnosis. Although rare, superior semicircular canal dehiscence shall be considered in conductive hearing loss with vestibular symptoms.

Contribution of Reformatted Multislice Temporal Computed Tomography Images in the Planes of Stenvers and Pöschl to the Diagnosis of Superior Semicircular Canal Dehiscence.

OBJECTIVE: In the diagnosis of superior semicircular canal dehiscence (SSCD), computed tomography (CT) is the only imaging method. The aims of the study were to show that reformat images are more accurate than standard planes for diagnosis of SSCD and to determine the prevalence of SSCD. METHODS: The retrospective review yielded 1309 temporal CTs performed in our radiology department for any reason. Two radiologist interpreted CTs in standard planes collaboratively. Patients with SSCD were reinterpreted in Pöschl and Stenvers planes by 2 radiologists separately. RESULTS: Statistical analysis was made by accepting that 2 radiologists diagnosis were accurate in Pöschl plane. Coronal plane sensitivity 86%, specificity 64%, Stenvers plane sensitivity 96%, and specificity 52% have been found in the mean result of 2 observers (P < 0.001). CONCLUSIONS: In the diagnosis of SSCD, standard and Stenvers planes can cause false-negative and false-positive diagnoses. Interpretation in Pöschl plane can significantly increase sensitivity, specificity, negative, and positive predictive values for diagnosing dehiscence.

TBX1 is required for normal stria vascularis and semicircular canal development.

Little is known about the role of TBX1 in post-otocyst stages of inner ear development. Here, we report on mice with a missense mutation of Tbx1 that are viable with fully developed but abnormally formed inner ears. Mutant mice are deaf due to an undeveloped stria vascularis and show vestibular dysfunction associated with abnormal semicircular canal formation. We show that TBX1 is expressed in endolymph-producing strial marginal cells and vestibular dark cells of the inner ear and is an upstream regulator of Esrrb, which previously was shown to control the developmental fate of these cells. We also show that TBX1 is expressed in sensory cells of the crista ampullaris, which may relate to the semicircular canal abnormalities observed in mutant mice. Inner ears of mutant embryos have a non-resorbed fusion plate in the posterior semicircular canal and a single ampulla connecting anterior and lateral canals. We hypothesize that the TBX1 missense mutation prevents binding with specific co-regulatory proteins. These findings reveal previously unknown functions of TBX1 during later stages of inner ear development.

Cautionary Findings for the Presence of Facial Canal Dehiscence During Cholesteatoma Surgery.

Our aim was to investigate the relationship between facial canal dehiscence (FCD) and surgical findings and procedures in patients with cholesteatoma. A total of 186 patients (118 males, 39.2 ± 15 years) who underwent surgery for advanced cholesteatoma between 2013 and 2018 were included in the study. The relationship between FCD and surgical findings was investigated via the surgical registries. The prevalence of FCD was 36.6% (68/186). The prevalence of FCD was 44%, and 13.2% for the patients who underwent canal wall down mastoidectomy (62/141) and canal wall up mastoidectomy (6/45), respectively (P < .001). Facial canal dehiscence was detected in 73.9% of the 23 patients who had a lateral semicircular canal (LSCC) defect (P < .001), in 61.9% of 21 patients who had a tegmen tympani defect, and in 58.1% of the 31 patients who had erosion on the posterior wall of the external auditory canal (EAC; P < .05). The prevalence of FCD was 3.1% in patients with isolated incus erosion, 59.1% in patients with erosion of malleus and incus, 60.7% in patients with erosion of stapes suprastructure and incus, and 43.2% in patients with whole ossicular chain deformation (P < .001). The defects on LSCC, EAC, tegmen tympani, and malleus and incus might be cautionary findings for the presence of FCD during cholesteatoma surgery.

Clinical Assessment of Patients with Bilateral Superior Semicircular Canal Dehiscence.

OBJECTIVE: Superior semicircular canal dehiscence (SSCD) is caused by a deformity in the arcuate eminence, leading to various vestibular and auditory symptoms that can manifest unilaterally or bilaterally. The aim of the present study was to distinguish the differences in symptoms, treatment options, and outcomes between patients with unilateral and bilateral SSCD. METHODS: A retrospective medical record analysis was conducted to identify patients with SSCD treated at a tertiary care center from March 2011 to May 2017. The patient demographic data, preoperative symptom presentation, and postoperative outcomes were extracted. Statistical analyses were performed using IBM SPSS Statistics. Fisher's exact tests were computed to investigate the relationships between binary variables, with a significance level of P < 0.05. RESULTS: A total of 99 patients with SSCD had been treated at our institution from March 2011 to May 2017. Of these 99 patients, 41 (41.4%) had a diagnosis of bilateral SSCD. Of the 41 patients with bilateral SSCD, 27 (65.9%) were women, and the mean age was 53.6 ± 10.9 years (range, 31.7-73.9). The most common presenting symptom was tinnitus (n = 33; 80.4%) and dizziness (n = 33; 80.4%). Previous trauma to the head correlated with a bilateral SSCD presentation (P = 0.04). Trends were reported between female sex and bilateral SSCD [r(35) = 0.32379; P = 0.0506]. Postoperatively, trends were also found, with greater rates of dizziness in patients with bilateral SSCD compared with those with unilateral SSCD (odds ratio, 3.81; P = 0.0659), and less improvement in dizziness (odds ratio, 0.186; P = 0.0627). No other significant differences were found between the symptoms or clinical outcomes and improvements between the bilateral and unilateral cohorts. CONCLUSION: Bilateral SSCD might result in different clinical symptoms that are more prevalent compared with unilateral SSCD. The findings from the present series of patients with bilateral SSCD suggest that patient symptoms and history are important in the diagnosis of bilateral SSCD and deciding whether 1 or both dehiscences requires surgical intervention.

Malformations of the lateral semicircular canal correlated with data from the audiogram.

OBJECTIVES: Lateral semicircular canal (LSCC) malformations  are one of the most common inner ear malformations. The purpose of this study is to analyze the prevalence and type of hearing losses associated with LSCC malformations, compared to a control group. MATERIALS AND METHODS: We retrospectively included 109 patients (166 ears) presenting with a CT-confirmed LSCC malformation, compared to a control group (24 patients). The bony island surface and the width of the inner portion of the LSCC were measured to confirm the malformation. There results were correlated to audiogram data: sensorineural (SHNL), mixed (MHL) or conductive hearing loss (CHL) by an otologist. RESULTS: In the LSCC group, 60.9% of patients presented with an audiogram-confirmed hearing loss, especially SNHL (39.2%, n = 65) and MHL (12.7%, n = 21). Hearing was normal in 39.2% (n = 65) of the cases. Bilateral LSCC malformations (n = 57) were frequently associated with hearing loss (80.7%), SNHL in most of the cases (33.3%). Unilateral LSCC malformations were associated with hearing alterations (51.9%, n = 27), but we also observed a high rate (81%, n = 42) of contralateral abnormalities of the audiogram. CONCLUSION: LSCC malformations are commonly associated with hearing loss (61%), especially SHNL (39%). The high rate (81%) of contralateral hearing disturbances in unilateral LSCC malformations should be taken into account in the patient's daily life to avoid triggering or exacerbating any hearing loss. Otologists and radiologists must cooperate to ensure that all malformations are correctly described on CT, especially to improve the patient's education regarding hearing preservation.

Relative Preservation of Superior Semicircular Canal Architecture in CHARGE Syndrome.

OBJECTIVES: (1) Describe common patterns of semicircular canal (SCC) anomalies in CHARGE syndrome (CS) and (2) recognize that in CS, the architecture of the superior SCC may be relatively preserved. STUDY DESIGN: This is a retrospective review of temporal bone imaging studies. SETTING: Quaternary care center. SUBJECTS AND METHODS: A sample of 37 patients with CS. All subjects met clinical diagnostic criteria for CS. The presence/absence of anomalies of the middle ear, mastoid, temporal bone venous anatomy, inner ear, and internal auditory canal was recorded. Anomalies of each SCC were considered separately and by severity (normal, dysplasia, aplasia). RESULTS: Thirty-seven subjects (74 temporal bones) were reviewed. Thirty-four (92.0%) patients demonstrated bilateral SCC anomalies. Three (8.0%) had normal SCCs. In patients with SCC anomalies, all canals demonstrated bilateral abnormalities. Thirty-two (86.5%) patients had bilateral horizontal SCC aplasia. These 32 patients also demonstrated posterior SCC aplasia in at least 1 ear. Of 74 temporal bones, 37 (50.0%) had superior SCC dysplasia. All dysplastic superior SCCs showed preservation of the anterior limb. Complete superior SCC aplasia was found in 28 (37.8%) temporal bones. CONCLUSION: SCC anomalies occur with high frequency in CS. Complete absence of the horizontal and posterior canals is typical and usually bilateral. By contrast, the superior SCC often demonstrates relative preservation of the anterior limb.

Dissociation between caloric and head impulse testing in patients with congenital abnormalities of the semicircular canals.

BACKGROUND: Dissociation between caloric and head impulse test results in patients with vestibular disorders has been well documented since the introduction of video head impulse testing. Prior to the introduction of video head impulse testing, vestibular diagnostic services relied mainly on caloric testing, and it is now known that the caloric testing shows more positive results than video head impulse testing. A dissipation model was proposed to explain this dissociation.Case reportsThis paper presents two cases in which caloric testing indicated an absent or significantly reduced response on the horizontal semicircular canal plane but video head impulse testing showed near-normal or normal vestibulo-ocular reflex gain on the same plane. CONCLUSION: This report supports the dissipation theory and questions the functional relevance of canal paresis values calculated from caloric test results.

Duplicated internal auditory canal with inner ear malformation: Case report and literature review.

Internal auditory canal anomalies are rare. Narrow internal auditory canal is believed to occur as a result of aplasia or hypoplasia of the vestibulocochlear nerve. Narrow duplication of the internal auditory canal is considered to be very rare. Narrow duplication of the internal auditory canal with inner ear malformation has been reported in only 3 cases. We present 2 cases of narrow duplication of the internal auditory canal with inner ear malformation. The first case had inner ear malformation on only one side and the second case had inner ear malformation on both sides. The embryogenesis may be different between internal auditory canal and inner ear.

Superior canal dehiscence with tegmen defect revealed by otoscopy: Video clip demonstration of pulsatile tympanic membrane.

Superior canal dehiscence is a pathologic condition of the otic capsule acting as aberrant window of the inner ear. It results in reduction of inner ear impedance and in abnormal exposure of the labyrinthine neuroepithelium to the action of the surrounding structures. The sum of these phenomena leads to the onset of typical cochleo-vestibular symptoms and signs. Among them, pulsatile tinnitus has been attributed to a direct transmission of intracranial vascular activities to labyrinthine fluids. We present the first video-otoscopic documentation of spontaneous pulse-synchronous movements of the tympanic membrane in two patients with superior canal dehiscence. Pulsating eardrum may represent an additional sign of third-mobile window lesion.