Otic Capsule Research Articles

This report presents for the first time a case of triple otic capsule dehiscence (OCD) of the labyrinthine-vascular type, with 2 dehiscences treated simultaneously and effectively by a recently described endovascular approach. Case report. Single otology/neurotology clinic. A 47-year-old male with triple otic capsule dehiscence (OCD) and associated symptoms. Improvement in the Tinnitus Handicap Inventory (THI) and Dizziness Handicap Inventory (DHI) scores. The first OCD was located between the internal jugular vein (IJV) and the posterior semicircular canal (SCC), and the second OCD was located between the vestibular aqueduct (VA) and the IJV. The third OCD, situated between the superior SCC and the superior petrosal sinus, remained untreated since it was considered less contributive to the patient's symptoms. The procedure involved (1) stenting of the right jugular vein combined with (2) coiling of a small portion of the vein in contact with the homonymous vestibular aqueduct. Early clinical signs, along with the audio-vestibular assessment, also suggested the diagnosis of right-sided endolymphatic hydrops. The outcome was uneventful, and the long-term follow-up showed promising results as the menieriform-like vertigo attacks disappeared after the procedure. THI and DHI scores were significantly improved. Auditory symptoms, including tinnitus, also progressively improved, especially after the fitting of a hearing aid. Multiple OCD (not only dehiscence of the superior SCC) should be systematically looked for on high-resolution computed tomography, given that a combined endovascular approach could be carried out in multiple labyrinthine-vascular forms.

Trauma-related inner ear disorders following head impacts can have various causes. The use of the more recent classification of temporal bone fractures into "otic capsule sparing" (OCS) and "otic capsule violating" (OCV) is useful in the context of medical assessment. The available imaging is often insufficient, and the consequences of otic capsule fractures are underestimated in emergency management. Therefore, indirect signs (e. g., hemotympanum, cerebrospinal fluid otorrhea, facial palsy) often must be evaluated. Even without radiological evidence of a fracture, temporary inner ear damage can occur, particularly through the mechanism of a head-impact acoustic trauma. Typical findings include hearing loss with a c5-notch, sometimes accompanied by tinnitus, and benign paroxysmal positional vertigo (BPPV) respectively. Persistent disorders may result not only from fractures but also from hemorrhage within the labyrinth. However, these are rarely detected in acute diagnostics and are therefore difficult to prove causally. If vertigo and dizziness persist after a head injury and symptoms worsen, persistent postural-perceptual dizziness (PPPD, functional dizziness syndrome) must be considered. Tinnitus invariably occurs in combination with a structurally and objectively verifiable hearing impairment.

Georg von Békésy’s initial observations of inner-ear vibrations were carried out at the apex of human-cadaver cochleae but contemporary studies have focused on responses at the base of the cochlea of live rodents. Apical cochlear recordings have proven difficult to achieve because opening the otic capsule often produces surgical injury and experimental artifacts. Using optical coherence tomography, I recorded mechanical responses to click stimuli at the organ of Corti (OoC) in the intact chinchilla cochlea at sites with characteristic frequencies (CFs) around 500 Hz. In general, OoC velocity responses to clicks consist of two segments: an initial component with a band-pass tuning centered at around 500 Hz, and a later component with low-pass characteristics. Spectral analysis of the transient responses revealed that responses had greater amplitudes and wider frequency bandwidth near the Hensen’s cells region than in the proximity of the basilar membrane, their frequency selectivity increased with stimulus level and death, and CF changes were negligible postmortem. Noise analysis, using Wiener kernels, indicates that click responses contain nonlinearities absent in first-order Wiener kernels. Click responses were well approximated by a frequency independent delay followed by a minimum-phase filter. The average length of the delay was approximately 1.1 ms.

The stylohyoid complex (SHC), comprising the styloid process (SP), stylohyoid ligament, and lesser horn of the hyoid bone, arises from Reichert’s cartilage and plays a central role in head and neck organization. Although anatomically small, it occupies a strategic position in the parapharyngeal space, linking neural, vascular, and visceral compartments. This review integrates embryological, comparative, anatomical, and clinical perspectives to provide an updated synthesis of SHC morphology and significance. Developmental studies highlight the early segmentation of Reichert’s cartilage, its transient relationships with the otic capsule, facial canal, and carotid arteries, and its role in shaping muscular and fascial compartments. Comparative anatomy demonstrates the evolutionary transition from a continuous ossicular chain to a vestigial human structure, reflecting a trade-off between rigidity and vocal tract flexibility. In humans, the SHC exhibits marked variability in length, angulation, segmentation, and ligamentous ossification, which directly influence its spatial relationships with the internal and external carotid arteries, the internal jugular vein, and the lower cranial nerves. These variations underpin the clinical spectrum of Eagle’s syndrome and vascular complications, including carotid artery dissection and jugular compression syndromes. Recognition of these embryological origins, evolutionary trajectories, and anatomical variants is essential for accurate diagnosis, imaging interpretation, and surgical planning. As both an embryological remnant and a clinical landmark, the SHC bridges fundamental anatomy with practical implications for imaging, diagnosis, and surgery.

Abstract Taphrosphyini is a diverse and geographically widely distributed lineage of bothremydid pleurodiran turtles. The first neuroanatomical reconstruction of the Paleogene genus of Taphrosphyini Taphrosphys is presented here, based on the study of a skull of the Moroccan Paleocene species Taphrosphys ippolitoi . Some osseous characters hitherto undocumented for this taxon are recognized in this specimen. Thus, among other anatomical elements, the postorbitals are documented for first time in this taxon, and the columella auris is described for the first time within Taphrosphyini. The use of the CT methodology and the three-dimensional modelling software allowed us to generate the three-dimensional virtual reconstruction of an idealized skull of Taphrosphys ippolitoi . This allows us to recognize several internal cranial structures and compare them with those of the other species of this genus. Most neuroanatomical elements of Taphrosphys ippolitoi are documented here. In addition of characters shared with all other bothremydids, others, shared exclusively with some representatives of this clade, are recognized as evidence for evaluate its lifestyle. The enlarged nasal cavity and the relatively high and wide semicircular canals of the endosseous labyrinth, confirmed here for Taphrosphyini, are convergent with those of other pleurodires identified as marine forms, including the Nigeremydini bothremydids. Thus, these and other anatomical and neuroanatomical traits observed in Taphrosphys ippolitoi are recognized as adaptative responses to marine environments.

Abstract Background Sensorineural hearing loss (SNHL) poses a significant public health burden globally, with a disproportionately higher prevalence in developing regions like Africa. The consequences of SNHL in early childhood can be devastating, impacting speech, language, cognitive, and psychosocial development, ultimately affecting educational attainment and quality of life. The etiology of SNHL is multifactorial, encompassing genetic predispositions, prenatal and perinatal complications, infections, ototoxic insults, and environmental factors. In the African context, preventable causes such as congenital rubella, meningitis, mumps, and ototoxic medications play a significant role. Additionally, the high prevalence of consanguineous marriages and the lack of universal newborn hearing screening programs contribute to delayed diagnosis and interventions. Early and accurate diagnosis of SNHL is crucial for timely and appropriate medical, surgical, or audiological (re)habilitative measures. Main body However, the diagnosis of SNHL, particularly in children, can be challenging, necessitating a combination of audiological and radiological evaluations. Audiological assessments; behavioral measures (pure-tone audiometry [PTA]), electroacoustic measures (immittance audiometry and otoacoustic emissions), and electrophysiologic measures (auditory brainstem response and auditory steady-state response) are comprehensive audiological assessments which remain the cornerstone for identifying the site, degree, and laterality of hearing loss. They cannot localize or detect the underlying pathology, and this may affect the determination of appropriate interventions such as hearing aids, cochlear implants, other amplification devices, and other management options. Radiological imaging techniques, particularly computed tomography and magnetic resonance imaging, have revolutionized the evaluation of SNHL by providing detailed visualization of the intricate anatomy and pathologies of the bony and membranous labyrinths, respectively. Conclusion SNHL poses a significant challenge in the African context, with a higher burden and unique etiological patterns. Early and accurate diagnosis, facilitated by the integration of audiological and radiological evaluations, is crucial for timely interventions and optimal outcomes.

Otosclerosis is a primary bone disorder of the otic capsule characterized by abnormal bone remodeling, leading to progressive conductive or mixed hearing loss, often accompanied by tinnitus. It affects approximately 0.3-0.4% of Caucasians, with lower prevalence in Asian and African populations, and accounts for 5-10% of adult-onset conductive hearing loss worldwide. Beyond auditory dysfunction, patients may present with associated symptoms such as tinnitus, vertigo, and, less commonly, rhinitis-like complaints due to Eustachian tube dysfunction, impacting quality of life. We present two cases—one fenestral and one cochlear otosclerosis—illustrating the clinical spectrum. HRCT remains the gold standard, while MRI assists in assessing cochlear involvement and excluding mimics. Advanced modalities, including ultra-high-resolution CT and photon-counting detector CT, further enhance lesion characterization. Given its global burden and potential for misdiagnosis, this study underscores the need for heightened awareness, timely imaging, and close collaboration between radiologists and otolaryngologists to optimize outcomes.

The labyrinthine geometry and functional anatomy of the semicircular canals have intrigued scientists for decades, and there has been considerable interest in understanding how these complex structures grow and develop with evidence emerging from human studies that size maturation occurs exceptionally early by comparison with other systems. Here we seek to extend the empirical evidence base and our understanding by investigating canal ontogeny in a non-human species. The postnatal development of the murine bony semicircular canals was investigated to determine the timing of size and shape maturation in relation to ossification of the surrounding otic capsule. Using micro-CT imaging and geometric morphometric analysis of 43 male C57BL/6J mice across six developmental stages (postnatal days 1-48 and 26 months), this study reveals that the semicircular canals undergo rapid growth and shape transformation within the first postnatal week. Ossification begins between P1 and P7, coinciding with the most significant observed increases in canal length and configuration shape. By P14, the canals are fully encased in a thin layer of bone, and subsequent changes are minimal, mostly in size, indicating morphological stabilization. This is further supported by a decrease in size variability as ossification progresses. These findings support the hypothesis that ossification imposes a progressively tighter constraint on canal form, as reflected by the gradual reduction in shape variation past the onset of ossification. Cross-section area shows negligible variation, suggesting early maturation of this feature. These findings highlight a brief but critical window of morphological plasticity in early postnatal life, with implications for interpreting vestibular development and fossil ontogeny in mammals.

Radiologic prevalence of otic capsule dehiscence and development of the Yenigun classification for semicircular canal dehiscence.

BackgroundTemporal bone fractures form a major skull-base injury subset, yet prognostic data—drawn chiefly from short-term Western cohorts—remain sparse. This study therefore investigated long-term audiometric and vestibular outcomes by otic-capsule integrity to refine recovery estimates and treatment efficacy.MethodsWe conducted a retrospective cohort study of 1,871 adults with traumatic temporal bone fractures treated at a Level I trauma center in China (2014–2023). Patients were stratified by otic capsule status: sparing (OCS, n = 1,617) vs. violating (OCV, n = 254). Primary outcomes included pure tone audiometry and Dizziness Handicap Inventory scores assessed over 24 months. Statistical analysis employed mixed-effects models, Kaplan-Meier survival analysis, and propensity score matching. Two a priori hearing endpoints were used: “normal hearing” (PTA ≤25 dB HL) and “functional hearing recovery” (≥30 dB improvement from baseline).ResultsBaseline hearing impairment was significantly worse in OCV patients (84.6 ± 8.7 vs. 45.1 ± 8.5 dB HL, p < 0.001). At 24-month follow-up, functional hearing recovery (≥30 dB improvement) occurred in 90.4% of OCS patients, whereas 0% of OCV patients reached this threshold; return to normal hearing (PTA ≤25 dB HL) was observed in 38.5% of OCS patients and 0% of OCV patients. Multivariable analysis identified OCV fracture as the strongest predictor of severe hearing loss (OR 4.89, 95% CI: 3.42–6.99, p < 0.001). Complication rates were five-fold higher in OCV patients (31.5 vs. 6.1%, p < 0.001), including cerebrospinal fluid leak (13.8 vs. 2.0%) and meningitis (4.3 vs. 0.7%). Propensity-matched analysis demonstrated surgical benefit, with 7.6 dB hearing improvement compared to conservative management (p = 0.001).ConclusionsOtic capsule integrity represents the primary determinant of recovery following temporal bone fractures. OCV fractures demonstrate profound, persistent deficits with minimal recovery potential, while OCS fractures show excellent recovery prospects. These findings provide crucial prognostic information for patient counseling and treatment planning in temporal bone trauma management.

Background: Computed tomography (CT) scanning is one of the most practical and precise diagnostic imaging methods used to evaluate birds’ heads. Objectives: This study aimed to present normal anatomical data of the head of a lovebird (Agapornis roseicollis) using the CT method. The features of the bird’s head were investigated in terms of bones, joints, muscles, sinuses, and other constituent tissues. Methods: This current retrospective cross-sectional study included carcasses of six adult lovebirds (A. roseicollis) (three males and three females), with an average age of 1–3 years and an average weight of 40–60 g. After preparing the CT images, the head of each parrot was subjected to gross anatomical examination. Results: Reconstructed CT images identified most structures of the lovebird (A. roseicollis) head. The parietal, mandibular, occiput, maxillary, preimaxillary, palatine, pterygoid, quadrate, temporal bones, epithelial membranes, external ear canal and bony labyrinth, ossicles, and entoglossal bones, different parts of the infraorbital sinus, brain hemispheres, and various parts of the eyeball and conchae of the nasal cavities were examined on the CT images. The results related to the CT evaluation and anatomical examination of the lovebird’s (A. roseicollis) head demonstrated a high correlation. Conclusion: The study’s results can be employed as a reference and a suitable atlas for identifying anatomical features, examining different species of lovebirds (A. roseicollis), teaching anatomy, interpreting CT scan images, performing clinical examinations, and treating this type of parrot.

Bilateral temporal bone fractures (TBFs) involving the otic capsule are uncommon, but can result in simultaneous severe auditory and vestibular dysfunction. We present the case of a 59 year-old male patient who experienced bilateral hearing loss and vertigo following a backward fall from a height of 2 m. Temporal bone computed tomography scans revealed bilateral fractures involving the otic capsule with hemorrhage in both mastoid cavities. Audiologic evaluation confirmed bilateral profound sensorineural hearing loss, and vestibular testing indicated bilateral vestibular hypofunction. The patient underwent unilateral cochlear implantation (CI) on the left side, resulting in improved aided hearing thresholds (~45 dB HL) and enhanced verbal communication. He also participated in customized vestibular rehabilitation, comprising 4 sessions over 8 weeks. Clinical improvement was observed in balance confidence, visual acuity during head movement, and postural control tests. The Dizziness Handicap Inventory score decreased from 16 to 0, while the Activities-Specific Balance Confidence Score increased from 59% to 78%. This case emphasizes the importance of integrated auditory and vestibular rehabilitation in patients with bilateral TBFs, demonstrating that CI combined with vestibular therapy can facilitate significant functional recovery.

The human cochlea is encased within the otic capsule, the densest bone in the body, posing significant challenges for anatomical imaging of cochlear structures. Because of difficult access and fragility of cochlear structures, our understanding of intracochlear anatomy has historically relied on postmortem histology. We thus have a limited understanding of human cochlear anatomy in its native, unfixed state. Clinical diagnostics for hearing loss, such as audiometry and otoacoustic emissions, offer functional assessments but fail to elucidate the often diverse underlying structural pathologies with any degree of precision. To address the critical need for assessing the human cochlear anatomy and associated pathologies without the risk of traumatizing cochlear structures, we imaged fresh cochleae in situ soon after death through the intact round window membrane with Optical Coherence Tomography (OCT) without inserting instruments inside or opening the cochlea. Micron-resolution OCT cross-sectional images of the human intracochlear structures were acquired and compared with corresponding histology systematically to aid in the identification of fine structural features and possible pathologies. With OCT imaging, we observed varied anatomy of the organ of Corti, and developed a cochlear “integrity” rating system to differentiate healthy appearing cochleae from various pathological states. These results demonstrate the capability of OCT to non-traumatically visualize cochlear integrity, highlighting its potential as a diagnostic tool. This work shows promise in translating the ability to determine the likelihood of existing or lack of hair cells and supporting cells in live patients, which would enable appropriate targeted treatments.

Hearing function and ossicular deformities and fractures in the oim mouse model of brittle bone disease.

The origin of middle ear ossicles: A narrative and illustrated historical review.

Applied microanatomy of the petrous internal carotid artery, greater superficial petrosal nerve, and tensor tympani muscle to improve safety during middle fossa surgery: laboratory cadaveric investigation.

ObjectiveTo evaluate patients' and caregivers' perceived benefit of using a custom 3-dimensional (3D)-printed transparent model of a skull with unilateral congenital aural atresia as a tool for surgical counseling.DesignProspective study.SettingTertiary academic children's hospital.Patients/ParticipantsTwenty-three families with children with congenital aural atresia.InterventionsA custom 3D-printed skull model was created from a computed tomography scan of a 5-year-old male patient with right unilateral congenital aural atresia, using transparent VEROCLEAR for bone and contrasting colors for the facial nerve, auditory ossicles, and bony labyrinth. This 3D model was used during standardized counseling about congenital aural atresia. Families were surveyed regarding their understanding of congenital aural atresia and their impressions of the model.Main Outcome MeasuresScale of 1 to 5 (strongly disagree to strongly agree) regarding utility of the 3D model.ResultsResources used most by families to learn about congenital aural atresia were online (57%) and doctor's visits (83%). Families strongly agreed that having a 3D model made it easier to understand the anatomy of congenital aural atresia (4.7/5, SD 0.5), the goals of surgical repair (4.7/5, SD 0.7), and the risks of atresiaplasty surgery (4.6/5, SD 0.6). Model use also increased reported comfort level with treatment decision-making (4.7/5, SD 0.6).ConclusionA novel, transparent 3D-printed model of congenital aural atresia that allows patients and families to visualize and physically interact with complex temporal bone anatomy could be a valuable, effective, and readily available tool to improve patient surgical counseling.

ABSTRACT Liaobatrachuszhaoi is an articulated, 3D-preserved frog from the Lower Cretaceous of China. Itsskull contains otic capsules that housed the membranous labyrinth, which isresponsible for positional awareness and hearing. However, the otic capsulecavities do not correspond exactly to this delicate soft-tissue organ, which isimmersed in fluid. Endocasts of these cavities can only be used to tentativelyreconstruct the statoacoustic organ. Therefore, we created 3D models fromhistological sections of extant basal frogs, Barbourula and Bombina, which arepresumably related to Liaobatrachus. To compare the size and proportions ofthese reconstructed membranous labyrinths with the internal cavities in theotic capsules of Liaobatrachus, we used the foramina in the medial wall of thecapsule through which branches of the eighth cranial nerve pass from thebraincase to the sensory cell of the membranous labyrinth in the capsule. Theinferred proportions of the utricle and saccule, as well as the size of thesemicircular ducts, are similar to those in extant basal frogs. However, as theacoustic sensitivity of frogs is related to the microstructure of two tinypapillae absent from the 3D models, it is impossible to draw any conclusionsabout the hearing capacity of Liaobatrachus.

The bony labyrinth of the petrosal bone, a distinctive feature of mammal skulls, is often identified in micro-computed tomography imaging to infer species' physiological and ecological traits. When done as part of a comparative study, one individual specimen is normally considered representative of a species, and intraspecific variation is considered low. Yet tests of intraspecific variability have been performed on few species and on limited morphological traits. Studies of intraspecific variability are not only valuable to help us assess the need for multiple specimens in comparative work, but relative levels of variability can also be used to reveal insights into a trait's functional significance. In this study, we report measurements of intraspecific variation on two cetaceans with vastly different auditory specializations, a low-frequency specialized mysticete and an echolocating odontocete. We examine the internal structures of the cochlea in beluga and bowhead whales and relate this to their hearing abilities. Overall levels of intraspecific variability are higher in the bowhead than the beluga, reflecting the more specialized auditory system of the latter. However, the levels of variation differ through the length of the cochlea (base to apex) and these appear to reflect known frequency specializations of the species, with the bowhead having lower variation in some measurements at the low-frequency apical end than the beluga.

The inner ear or the labyrinth performs the function of hearing and balance. It consists of a bony and a membranous labyrinth. Bony labyrinth consists of three parts – the vestibule, cochlea and the semicircular canals. Membranous labyrinth consists of the cochlear duct, the utricle and saccule, the three semicircular ducts, and the endolymphatic duct and the sac. The membranous labyrinth contains fluids which are in a state of dynamic equilibrium with the intracranial cerebrospinal fluid. Basilar membrane displacements result in electrolyte alterations and thus generate nerve impulses. Scala media is filled with endolymph that can be distinguished by its ion composition that is much like an intracellular character with respect to its potassium content. Scala tympani and scala vestibuli are filled with perilymph containing an extracellular-like ion composition and communicate at the apex of the cochlea via the helicotrema. The fluid contained within the tunnel of Corti and Nuel's spaces within the sensory epithelium resembles composition of the perilymph. The disturbance in the milieu interior is consequent to auditory and vestibular impairments. The unique anatomy of the membranous labyrinth shall be elaborated.