Middle ear malformations (MEMs) represent a diverse group of congenital anomalies with significant implications for auditory function. These malformations, which occur in approximately 0.5 to 3% of conductive hearing loss cases, can arise from various genetic and environmental factors. They often manifest unilaterally and may occur in isolation or as part of a syndromic condition. MEMs are closely associated with abnormalities of the external ear and less frequently with inner ear anomalies.Embryologically, the middle ear develops from the first and second pharyngeal arches, with interactions between the ectoderm and endoderm contributing to the formation of essential structures such as the tympanic membrane, ossicles and Eustachian tube. Disruptions in these developmental processes can lead to a spectrum of MEMs, ranging from minor defects to severe malformations affecting multiple middle ear components.Clinical management of MEMs requires a multidisciplinary approach, involving otolaryngologists, pediatricians, and audiologists. Early intervention with appropriate hearing aids, including conventional hearing aids and bone conduction devices, is essential to mitigate the impact of conductive hearing loss on speech and language development, particularly in children.Surgical planning involves comprehensive preoperative assessment, including high-resolution computed tomography imaging to evaluate middle ear anatomy, the facial nerve course, and vascular anomalies. Traditional surgical approaches such as stapesplasty and tympanoplasty remain mainstays for correcting specific middle ear defects, while advances in technology have expanded the role of active middle ear implants in treating special cases.In conclusion, MEMs represent a heterogeneous group of congenital anomalies with diverse etiologies and clinical implications. A thorough understanding of their embryological basis, genetic underpinnings, and surgical management strategies is crucial for optimizing outcomes in affected individuals.

This study aims to analyze the imaging features of isolated congenital middle ear malformation (CMEM) on high-resolution computed tomography (HRCT). We retrospectively collected patients with surgically confirmed diagnosis of isolated CMEM in our hospital between January 2018 and June 2023. All patients underwent HRCT before surgery. The preoperative imaging findings were analyzed by neuroradiologists with full knowledge of the intraoperative findings. 37 patients were included in this study, including 25 males and 12 females, with a median age of 16 years. A total of 44 ears underwent surgery. The most commonly affected structures were incudostapedial joint, incus long process, and stapes superstructure, followed by stapes footplate, oval window, incudomalleolar join, tympanic segment of the facial nerve canal, incus body, incus short process and malleus. All incus defect/hypoplasia/malposition, stapes superstructure deformity, malleus deformity, incudostapedial joint discontinuity, and facial nerve canal malposition/abnormal bifurcation could be observed on HRCT. Additionally, 96.0% of stapes superstructure defect, 85.7% of oval window atresia, and 41.7% of incudomalleolar joint fusion, could be visualized on HRCT. HRCT could not show ossicular soft tissue pseudo-connection and stapes footplate fixation. Preoperative HRCT is an important tool for diagnosing isolated CMEM. The advantages of HRCT lie in its ability to detect ossicular defects/deformities, incudostapedial joint discontinuity, oval window atresia, and facial nerve abnormalities. However, it has a low detection rate for incudomalleolar joint fusion and cannot show ossicular soft tissue pseudo-connection and stapes footplate fixation.

A variety of congenital and acquired disorders result in pediatric conductive hearing loss. Malformations of the external auditory canal are invariably associated with malformations of the middle ear space and ossicles. Isolated ossicular malformations are uncommon. Syndromes associated with external and middle ear malformations are frequently associated with abnormal development of first and second pharyngeal arch derivatives. Chronic inflammatory disorders include cholesteatoma, cholesterol granuloma, and tympanosclerosis.

A few studies have reported transcanal endoscopic management of isolated congenital middle ear malformations (CMEMs). The purpose of this study is to describe our surgical experience in endoscopic ear surgery for isolated CMEMs and evaluate the surgical effect of hearing reconstruction. From January 2017 to January 2022, a retrospective study was performed on 36 patients (37 ears) with isolated CMEMs who all underwent endoscopic surgery. Demographic data, high-resolution computed tomography (HRCT) findings, intraoperative findings, surgical management and audiometric data were recorded. Anomalies were categorized according to the Teunissen and Cremers classification system: 8 ears were categorized as class I, 8 ears as class II, 19 ears as class III and 2 ears as class IV. The air conduction pure tone average (AC-PTA) of 37 cases was 61.5 ± 8.6 dB preoperatively and 29.6 ± 6.9 dB postoperatively (p < 0.001). The mean preoperative air-bone gap (ABG) significantly decreased from 43.1 ± 8.7 dB to 12.8 ± 5.5 dB postoperatively. 36 of 37 cases (97%) met the criteria for successful operation. Isolated CMEMs are mainly manifested as aplasia of the stapes' superstructure and dysplasia of the long process of the incus. Transcanal endoscopic surgery seems a safe technique for the management of isolated CMEMs.

To evaluate and classify developmental malformations of the human stapes. Twenty-five temporal bone specimens from 18 patients with congenital stapes malformations were identified in the Mass Eye and Ear temporal bone collection. Serial sections stained with hematoxylin and eosin were examined by light microscopy and the morphology of the stapes was compared to age-matched controls. Each case of stapes malformation could be classified into one of four malformation types based on our current understanding of the embryologic origin of the subunits of the stapes and timing of development. Twenty-seven percent of stapes malformations had a Type I morphology characterized by a hypoplastic or absent inner footplate and hypoplastic to absent mesoderm footplate or oval window. The crura and capitulum may be absent, monopodal or dysmorphic. Eleven percent expressed a Type II malformation with dysmorphic or monopodal capitulum and crura and a fixed footplate. Twenty-seven percent were of Type III with a dysmorphic or monopodal capitulum and or crura. The footplate, and thereby oval window is present and without fixation. The most common malformation, Type IV, was isolated footplate fixation observed in 33% of cases. Malformations of the human stapes follow consistent patterns of early or late disruptions of the stapes subunits of mesodermal and/or neural crest origin. While the molecular events, including temporal coordination, that lead to a normally formed stapes are not yet fully understood, the observed patterns of human stapes malformation can be consistently classified into one of four patterns of developmental disruption.