Perspective on Temporomandibular Joint Disorder: Foramen Tympanicum Defect.

BACKGROUND: Foramen tympanicum (FT) is a defect located anterior-inferior to the external acoustic meatus. We evaluated its prevalence, location, size, and relationship with temporomandibular joint (TMJ) disorders. METHODS: Cone beam computed tomography was performed for 200 patients who presented to the Karamanoglu Mehmetbey University Ahmet Kelesoglu Faculty of Dentistry Hospital. The location and size of the FT in the axial and sagittal planes were evaluated. Descriptive statistics were used to compare the study parameters among age and sex groups. Patients with FT were reevaluated by two maxillofacial surgeons at the study centre. RESULTS: In total, 200 images from 400 joints were examined. Unilateral and bilateral FT (19 [9.5%] and 8 [4%], respectively) was detected in 35 (17.5%) images from 27 (13.5%) patients. Examinations were performed for TMJ disorders in 24 patients. Participants with bilateral defects had the highest rates of presence of sounds and ear pain on the left and right sides (p < .05). CONCLUSION: Foramen tympanicum can lead to TMJ disorders and spread of tumours or infections from the external auditory canal to the infratemporal fossa. The increased prevalence of such disorders in patients with bilateral FT suggests an association between them.

Epithelial dynamics shed light on the mechanisms underlying ear canal defects.

Defects in ear canal development can cause severe hearing loss as sound waves fail to reach the middle ear. Here, we reveal new mechanisms that control human canal development and highlight for the first time the complex system of canal closure and reopening. These processes can be perturbed in mutant mice and in explant culture, mimicking the defects associated with canal atresia. The more superficial part of the canal forms from an open primary canal that closes and then reopens. In contrast, the deeper part of the canal forms from an extending solid meatal plate that opens later. Closure and fusion of the primary canal was linked to loss of periderm, with failure in periderm formation in Grhl3 mutant mice associated with premature closure of the canal. Conversely, inhibition of cell death in the periderm resulted in an arrest of closure. Once closed, re-opening of the canal occurred in a wave, triggered by terminal differentiation of the epithelium. Understanding these complex processes involved in canal development sheds light on the underlying causes of canal atresia.

Imaging the External Ear: Practical Approach to Normal and Pathologic Conditions.

The external ear (EE) is an osseous-cartilaginous structure that extends from the auricle to the tympanic membrane. It is divided into two parts: the auricle (or pinna) and the external auditory canal (EAC). Given the ease of access to the EE, imaging studies are not always needed to make a diagnosis. However, when lesions block visual access to areas deep to the EE abnormality, complications are suspected, or there is lack of response to treatment, imaging becomes essential. A basic understanding of the embryologic development and knowledge of the anatomy of the auricle and EAC are useful for accurate diagnosis of EE lesions. Congenital, traumatic, inflammatory, neoplastic, and vascular conditions can affect the EE. An overview of the anatomy and embryologic development of the EE is presented, with discussion and illustrations of common and uncommon conditions that affect EE structures and a focus on the CT and MRI features that are of interest to radiologists. CT is usually the first diagnostic modality used to evaluate the EAC and is the superior method for demonstrating bone changes. MRI provides excellent tissue characterization and enables one to better define lesion extension and perineural tumor spread. In addition, a flowchart to facilitate the differential diagnosis of EE abnormalities is provided. Online supplemental material is available for this article. ©RSNA, 2022.

Whole-Genome Sequencing Identifies Two Novel Rare Mutations in BMP5 and BMP2 in Monozygotic Twins With Microtia.

ABSTRACT: Microtia is a rare congenital anomaly of the ear; it is regulated by both genetic and environmental factors. However, the mechanisms underlying its pathogenesis are unknown. In this study, the genomes of 2-year-old twin sisters with right microtia were sequenced using human genome-wide sequencing, an approach useful for identifying mutations in genes responsible for congenital microtia. The phenotypes of the twin sisters included congenital microtia on the right side, abnormal auricle shape in the right external ear, a peanut shape for the residual ear, and complete atresia of the right external auditory canal. In the twin sisters, we identified a previously unknown mutation in BMP5(exon4:c.833- 4C>G), as well as a new mutation (exon2:c.G332T:p.S111I) in BMP2, both of which were confirmed using polymerase chain reaction-based amplification of the corresponding genome regions, followed by first-generation sequencing. The exon4:c.833-4C>G mutation in human BMP5 may be the main cause of microtia in the twin sisters. A pathogenic mutation in human BMP2 (exon2:c.G332T:p.S111I) may be responsible for the facial deformity in the twin sisters. Thus, our study demonstrates the potential of genome-wide sequencing for identifying novel mutations associated with microtia on the whole-genome scale and extends the mutation spectrum of BMP5. Additionally, our data suggest that BMP2 is another pathogenic gene associated with microtia.

[Surgical management of high-grade ear malformations in childhood]. / Chirurgische Therapie komplexer Fehlbildungen des kindlichen Ohrs.

Malformations of the ear are the most common dysplasias in childhood. Ear malformations are classified into dysplasias of the auricle, of the ear canal, and of the middle and inner ear. The latter types are fortunately relatively rare. Most common is a low-grade dysplasia of the auricle (otapostasis, cup ear). Higher-grade dysplasia of the auricle (microtia II-III) is often associated with syndromes and/or malformations of the ear canal and the middle ear (e.g., congenital aural atresia with high-grade microtia and dysplasia of the middle ear). Functional aspects of hearing and acquisition of language as well as aesthetic aspects emphasize the importance of surgical therapy. Due to the importance of correctly scheduling surgical treatment in early childhood, this article gives an overview of the possibilities for aesthetic reconstruction of the auricle and the frequently associated functional rehabilitation of hearing.

Pleomorphic Adenoma of External Auditory Canal: Case Report of First Endoscopic Resection and Literature Review.

Ceruminous pleomorphic adenoma is a very rare, mostly benign tumor originating from the ceruminal glands in the external auditory canal. Histologically, it is a mixed tumor with epithelial and stromal parts of different proportions, and is recognized today by the World Health Organization (WHO) as a ceruminous adenoma. Similar to the pleomorphic adenoma of salivary glands, recurrence or malignant degeneration with cellular atypia and metastasis can occur on rare occasions. Here, we describe an 87-year old female patient with a growing spherical mass in the right external auditory canal. After exclusive endoscopic tumor resection, a ceruminous pleomorphic adenoma was histologically diagnosed. Due to the absence of nuclear pleomorphism, no increased mitotic rate, no perineural invasion and no fusion transcripts of the MYB or MYBL1 gene loci, an adenoid cystic carcinoma could be excluded. The postoperative course was without any evidence of complications. A literature review identified 44 articles with 49 patients that were considered. Hearing loss and ear sensations were the most commonly reported symptoms. Most cases underwent an excision via an endaural or retroauricular approach. Recurrences were described in four patients, three of which had a malignant transformation.

Active transcutaneous bone conduction implant: audiological results in paediatric patients with bilateral microtia associated with external auditory canal atresia.

OBJECTIVE: To describe, in terms of functional gain and word recognition, the audiological results of patients under 18 years of age implanted with the active bone conduction implant, Bonebridge™. DESIGN: Retrospective case studies conducted by reviewing the medical records of patients receiving implants between 2014 and 2016 in the public health sector in Chile. STUDY SAMPLE: All patients implanted with the Bonebridge were included (N = 15). Individuals who had bilateral conductive hearing loss, secondary to external ear malformations, were considered as candidates. RESULTS: The average hearing threshold one month after switch on was 25.2 dB (95%CI 23.5-26.9). Hearing thresholds between 0.5 and 4 kHz were better when compared with bone conduction hearing aids. Best performance was observed at 4 kHz, where improvements to hearing were observed throughout the adaptation process. There was evidence of a significant increase in the recognition of monosyllables. CONCLUSIONS: The Bonebridge implant showed improvements to hearing thresholds and word recognition in paediatric patients with congenital conductive hearing loss.

Incidence of Foramen Tympanicum (of Huschke): Comparing Cadaveric and Radiologic Studies.

PURPOSE: The foramen tympanicum (FT) represents a developmental anomaly that forms due to incomplete fusion of processes of the tympanic ring. Its presence in the population is controversial and it has been associated with a number of otologic complications. The aim of this study was to systematically analyze the prevalence, anatomical characteristics, and ethnic variations of the FT and compare these parameters in cadaveric and radiologic studies. METHODS: An extensive search was conducted through the major electronic databases, and identified articles were separated into 2 groups based on their methodology: cadaveric and radiologic studies. Data extracted included study modality, prevalence data, ethnicity, gender, side, laterality, and diameter. RESULTS: A total of 8 studies (n = 2671 patients) were included into our meta-analysis. The main findings revealed that the prevalence of the FT in the population is 14.9%, it is more often unilateral (62.5%) than bilateral (37.5%), it is most often reported in Asia (21.4%), and it is more prevalent in cadavers (21.2%) than in radiologic studies (8.8%) (not statistically significant). CONCLUSION: As the FT is present in more than one-tenth of the population, it is important to consider the possibilities of its presence when undertaking surgical procedures in the temporomandibular joint and ear region and plan accordingly to avoid injuries. Clinicians should keep it as one of the possible diagnoses while confronted with patients presenting with otologic complications. The use of newer imaging techniques was recommended, such as cone-beam computer tomography to detect the FT prior to surgery.

Audiological features in congenital bony atresia of external auditory canal with temporal-mandibular joint retroposition.

OBJECTIVES: To facilitate the diagnosis, treatment and surgical options for congenital bony atresia of external auditory canal (EAC) with temporal-mandibular joint (TMJ) retroposition by analyzing its audiological features and the morphology of temporal bone on CT scan. MATERIALS AND METHODS: Two cohorts of patients with congenital EAC bony atresia with (n=23) or without (n=21) TMJ retroposition were recruited from September 2012 to July 2014 at Beijing Tongren Hospital, Capital Medical University. The patients with TMJ retroposition were set as the group A and those without as group B. Based on the degree of TMJ retroposition, group A was further divided into two sub-groups A1 (n=13) and A2 (n=10). The temporal bone CT scan, pure tone average (PTA) and air-bone gap (ABG) were obtained for the main outcome measurements. SPSS 17.0 was used for the statistics analysis with t and t test. RESULTS: For group A, the average air conduction (AC) was 55.22±12.53dBHL, the average bone conduction (BC) was 7.07±3.34dBHL, and the average ABG was 50.69±8.60dBHL. For the sub-groups A1 and A2, the average AC was respectively 45.77±8.43dBHL and 59.50±7.43dBHL, BC 7.07±3.34dBHL and 6.89±4.37dBHL, and ABG 47.31±7.92dBHL and 53.00±7.91dBHL. For group B, the average AC was 70.24±5.63dBHL, BC 6.78±4.37dBHL, and ABG 60.19±6.09dBHL. CONCLUSIONS: The degree of TMJ retroposition is negatively related to the severity of hearing loss among patients with congenital EAC bony atresia, and those with TMJ have suffered less severe hearing loss than those without. Although TMJ retroposition might be a disadvantage for patients undergoing EAC plasty and tympanoplasty, it must be considered for its influence on hearing loss severity and auditory canal abnormality when planning the surgical treatment. Different from normal surgical protocol for congenital EAC bony atresia, we commend other hearing reconstruction methods such as BAHA and VSB, even without intervention.

Bilateral microtia, canal atresia and aplasia of cochleovestibular nerve.

A six-month-old baby with congenital patent ductus arteriosus (PDA), bilateral microtia and canal atresia was referred for hearing assessment. The audiology assessment revealed bilateral profound hearing loss, which is atypical for a case of pure canal atresia. Imaging was performed much earlier than usual and, as suspected, the patient also had bilateral severe inner ear anomaly. It is extremely rare for a person to have both external and inner ear anomaly because of the different embryological origin. The only suitable hearing rehabilitation option for this kind of patients is brainstem implant. However, the parents had opted for sign language as a form of communication.

SAMS, a syndrome of short stature, auditory-canal atresia, mandibular hypoplasia, and skeletal abnormalities is a unique neurocristopathy caused by mutations in Goosecoid.

Short stature, auditory canal atresia, mandibular hypoplasia, and skeletal abnormalities (SAMS) has been reported previously to be a rare, autosomal-recessive developmental disorder with other, unique rhizomelic skeletal anomalies. These include bilateral humeral hypoplasia, humeroscapular synostosis, pelvic abnormalities, and proximal defects of the femora. To identify the genetic basis of SAMS, we used molecular karyotyping and whole-exome sequencing (WES) to study small, unrelated families. Filtering of variants from the WES data included segregation analysis followed by comparison of in-house exomes. We identified a homozygous 306 kb microdeletion and homozygous predicted null mutations of GSC, encoding Goosecoid homeobox protein, a paired-like homeodomain transcription factor. This confirms that SAMS is a human malformation syndrome resulting from GSC mutations. Previously, Goosecoid has been shown to be a determinant at the Xenopus gastrula organizer region and a segment-polarity determinant in Drosophila. In the present report, we present data on Goosecoid protein localization in staged mouse embryos. These data and the SAMS clinical phenotype both suggest that Goosecoid is a downstream effector of the regulatory networks that define neural-crest cell-fate specification and subsequent mesoderm cell lineages in mammals, particularly during shoulder and hip formation. Our findings confirm that Goosecoid has an essential role in human craniofacial and joint development and suggest that Goosecoid is an essential regulator of mesodermal patterning in mammals and that it has specific functions in neural crest cell derivatives.

Mouse Hoxa2 mutations provide a model for microtia and auricle duplication.

External ear abnormalities are frequent in newborns ranging from microtia to partial auricle duplication. Little is known about the molecular mechanisms orchestrating external ear morphogenesis. In humans, HOXA2 partial loss of function induces a bilateral microtia associated with an abnormal shape of the auricle. In mice, Hoxa2 inactivation at early gestational stages results in external auditory canal (EAC) duplication and absence of the auricle, whereas its late inactivation results in a hypomorphic auricle, mimicking the human HOXA2 mutant condition. By genetic fate mapping we found that the mouse auricle (or pinna) derives from the Hoxa2-expressing neural crest-derived mesenchyme of the second pharyngeal arch, and not from a composite of first and second arch mesenchyme as previously proposed based on morphological observation of human embryos. Moreover, the mouse EAC is entirely lined by Hoxa2-negative first arch mesenchyme and does not develop at the first pharyngeal cleft, as previously assumed. Conditional ectopic Hoxa2 expression in first arch neural crest is sufficient to induce a complete duplication of the pinna and a loss of the EAC, suggesting transformation of the first arch neural crest-derived mesenchyme lining the EAC into an ectopic pinna. Hoxa2 partly controls the morphogenesis of the pinna through the BMP signalling pathway and expression of Eya1, which in humans is involved in branchio-oto-renal syndrome. Thus, Hoxa2 loss- and gain-of-function approaches in mice provide a suitable model to investigate the molecular aetiology of microtia and auricle duplication.

Ectopic external auditory canal and ossicular formation in the oculo-auriculo-vertebral spectrum.

Ear abnormalities in oculo-auricular-vertebral spectrum commonly present with varying degrees of external and middle ear atresias, usually in the expected locations of the temporal bone and associated soft tissues, without ectopia of the external auditory canal. We present the unique imaging of a 4-year-old girl with right hemifacial microsomia and ectopic location of an atretic external auditory canal, terminating in a hypoplastic temporomandibular joint containing bony structures with the appearance of auditory ossicles. This finding suggests an early embryological dysfunction involving Meckel's cartilage of the first branchial arch.

Applications of titanium mesh tubing in external ear canal reconstruction in congenital aural atresia.

The aim of this study was to observe the effect of a titanium tube on external auditory canal reconstruction in congenital aural atresia and to assess the tube's effectiveness in preventing external canal stenosis or atresia after reconstruction. Reconstruction of the external ear canal with a titanium mesh tube was performed in 16 patients (16 ears) with congenital aural atresia at the First People's Hospital of Foshan. The titanium mesh tube was removed 1 year after surgery. The patients were followed up for 2 years (2 ± 0.3 years), and all of the patients had formed a new external ear canal. There was no local infection, granulation tissue, re-stenosis, or atresia in any of the patients after surgery. All of the patients were content with their newly formed external ear canal. Titanium mesh tubing is safe and effective for reconstruction of the external ear canal during surgery for congenital aural atresia.

Lambdoid Synostosis Versus Positional Posterior Plagiocephaly, a Comparison of Skull Base and Shape of Calvarium Using Computed Tomography Imaging.

The differential diagnostics between the common positional posterior plagiocephaly and relatively rare lambdoid synostosis is important due to the differences in their treatment plan and clinical management. However, the clinical criteria for the diagnosis of lambdoid synostosis are not clear since there is a considerable overlap in the features of positional posterior plagiocephaly and unilateral lambdoid synostosis. To systematically evaluate the clinical findings in these 2 patient groups, we quantitatively compared the characteristics of endocranial skull base and ectocranial calvarium in 3D computed tomography, in 9 children (mean age 2.9 years) with unilateral lambdoid synostosis and 9 children with positional posterior plagiocephaly. The groups were sex and age matched. Our results show that the skull bases in the lambdoid synostosis are posteriorly shorter and more twisted than in positional posterior plagiocephaly. Anterior twisting was mild in both skull types. Our study confirmed earlier suggested diagnostic feature: prominent ipsilateral mastoidal bossing downward and laterally in all lambdoid skulls. In positional posterior plagiocephaly the bossing was typically not detected. Interestingly, there was a great variation in the position of the ipsilateral ear and external auditory meatus in both patient groups. Thus, neither antero-posterior nor vertical position of ear is a reliable differential diagnostic feature between lambdoid synostosis or positional posterior plagiocephaly.

Postnatal Diagnosis of a Baby With Multiple Rare Congenital Anomalies Including Syngnathia, Brain Dysmorphism, and Skin Pigmentation.

Syngnathia is a rare congenital disorder of jaw fusion with a paucity of literature from developed countries. We present a case of an infant noted to have multiple anomalies at birth including syngnathia, microcephaly with a variant of brain abnormality between holoprosencephaly and syntelencephaly, optic nerve hypoplasia, ear canal anomalies, hemi-vertebrae, and suspected hypomelanosis of Ito. To our knowledge, this patient with syngnathia and multiple anomalies is the first to be reported, but whether they are a coincidence, a pathogenetic association, or a new syndrome remains unknown. This case is discussed with a brief review of the literature.

Otologic Manifestations of Autosomal Recessive Congenital Ichthyosis in Children.

BACKGROUND: Few studies have investigated ear involvement in nonsyndromic autosomal recessive congenital ichthyosis (ARCI). OBJECTIVES: To assess the type and frequency of otologic manifestations of ARCI in patients under follow-up at the pediatric dermatology department of our hospital. MATERIALS AND METHODS: We prospectively studied the presence of ear pain, ear itching, tinnitus, otitis, cerumen impaction, accumulation of epithelial debris, and hearing loss. Daily hygiene measures, topical treatments, medical-surgical interventions, and frequency of visits to an ear, nose, and throat (ENT) specialist were noted in the patients' medical records. Ear examination and hearing tests were performed in all cases. RESULTS: Ten patients were studied: 2 had a self-healing collodion baby phenotype and 8 had ichthyosis. There was mention of otologic manifestations in the records of all 8 patients with ichthyosis (100%); 6 of these patients (75%) had abnormalities in the external auditory canal examination and 2 (25%) had conductive hearing loss. Our findings are limited by the small number of patients studied, all of whom were younger than 19 years. CONCLUSIONS: The involvement of both dermatologists and ENT specialists in the management of patients with ichthyosis is crucial to ensure the application of the best therapeutic and preventive measures. More studies are needed to assess the prevalence and impact on quality of life of ear involvement in patients with ichthyosis and to determine the optimal interval between ENT visits for these patients.

Disruption of teashirt zinc finger homeobox 1 is associated with congenital aural atresia in humans.

Congenital aural atresia (CAA) can occur as an isolated congenital malformation or in the context of a number of monogenic and chromosomal syndromes. CAA is frequently seen in individuals with an 18q deletion, which is characterized by intellectual disability, reduced white-matter myelination, foot deformities, and distinctive facial features. Previous work has indicated that a critical region for CAA is located in 18q22.3. We studied four individuals (from two families) with CAA and other features suggestive of an 18q deletion, and we detected overlapping microdeletions in 18q22.3 in both families. The minimal region of deletion overlap (72.9-73.4 Mb) contained only one known gene, TSHZ1, which was recently shown to be important for murine middle-ear development. Sequence analysis of the coding exons in TSHZ1 in a cohort of 11 individuals with isolated, nonsyndromic bilateral CAA revealed two mutations, c.723G>A (p.Trp241X) and c.946_947delinsA (p.Pro316ThrfsX16), and both mutations predicted a loss of function. Together, these results demonstrate that hemizygosity of TSHZ1 leads to congenital aural atresia as a result of haploinsufficiency.

Evaluation of foramen tympanicum using cone-beam computed tomography in orthodontic malocclusions.

The foramen tympanicum is a persistent anatomic formation of the temporal bone due to a defect in ossification normal bone physiology in neonatal or postnatal period. This study determined the occurrence and location of the foramen tympanicum in a Turkish sample using cone-beam computed tomography. Scans of 370 sites in 185 patients were retrospectively analyzed to determine foramen tympanicum occurrence, sizes, and locations according to their orthodontic malocclusions. Measurements were done on axial and sagittal sections to identify the dimensions. Differences in foramen tympanicum incidence by measurements, sex, side, malocclusions, and location were statistically evaluated. Foramen tympanicum was determined in 42 (22.7%) of 185 patients. No statistical difference was found considering location and sex (P > 0.05), but it was found more bilaterally in female patients within significance level at P = 0.024. Mean sizes did not differ significantly by sex but were found to be greater in females. In axial diameter, the average measurement was found wider on the right side of all patients (P = 0.017). The findings showed a greater foramen tympanicum dimension among class II than among class I and III subjects (P < 0.05). Knowledge about these structures is helpful for the interpretation of imaging (especially cone-beam computed tomography) and provides valuable information especially before orthognathic surgery to avoid intraoperative reconstruction and complications.

[A fully-implantable active hearing device in congenital auricular atresia]. / Vollimplantierbares Hörsystem bei Atresia auris congenita.

Active implantable hearing devices were primarily developed for sensorineural hearing loss. The vibrator coupling mechanisms were oriented towards normal middle ear anatomy and function. The aim of this project was to modify the only fully implantable hearing device with an implantable microphone for application in congenital auricular atresia, Carina™, and to introduce the modified device into the clinic. A special prosthesis was developed for the transducer and its individual coupling achieved by a special cramping system. The system was implanted in 5 patients with congenital auricular atresia. Audiological results were good; with patients' hearing gain exceeding 30 dB HL. Anatomic limits to the system's indications and technical drawbacks are also discussed.