Patterns of Anomalies of Structures of the Middle Ear and the Facial Nerve as Revealed in Newborn Temporal Bones

What's Your Diagnosis? Symptoms: Middle Ear Mass and Unilateral Hearing Loss

The patient’s imaging features, especially the honeycomb pattern of ossific changes in the geniculate fossa, were virtually pathognomonic for ossifying hemangioma of the facial nerve.

The purpose of this study is to categorize anomalous tympanic facial nerve (FN) on high-resolution computed tomography (HRCT) and to determinate the significance of associated temporal bone anomalies and congenital syndromes without microtia in patients with hearing loss. A retrospective analysis of HRCT findings in 30 temporal bones in 18 patients with anomalous FN was performed. Abnormalities of the tympanic FN were categorized as follows: category 1: FN medially positioned, but above the oval window; category 2: FN in the oval window niche; and category 3: FN below the oval window. Potential associated findings that were assessed included stapes abnormalities, oval window atresia, and inner ear anomalies, as well as the presence of a known congenital syndrome with hearing loss. The most common type of anomalous tympanic FN was category 1 (67%, n = 20), following by group 2 (20%, n = 6) and group 3 (13%, n = 4). Stapes anomalies were detected in 77% of temporal bones (n = 23), oval window atresia was detected in 43% of temporal bones (n = 13), and inner ear anomalies were detected in 70% of temporal bones (n = 21). Anomalous tympanic facial nerves in temporal bone with conductive hearing loss were often (60%) not associated with oval window atresia. The combination of aberrant tympanic FN and inner ear anomalies was significantly (P = .038) associated with a known congenital syndrome (6 patients), including CHARGE syndrome, oculo-auriculo-vertebral spectrum, Pierre-Robin sequences, and Down syndrome. Therefore, an anomalous tympanic FN in conjunction with inner ear anomalies appears to be a biomarker for certain congenital syndromes with hearing loss in the absence of microtia.

Symptoms: Unilateral Hearing Loss and Facial Paresis

Objective: To summarize the clinical features and postoperative efficacy of patients with oval window atresia accompanied by facial nerve aberration. Methods: The clinical data of patients with congenital middle ear malformation with facial nerve aberration admitted to our hospital from January 2015 to March 2023 were retrospectively analyzed. There were 97 cases (133 ears) in total. Among them, 39 patients (44 ears) had complete follow-up data, including 27 male patients and 12 females, aged 7-48 years old, with an average age of 17.8 years old. Of these, 14 cases (16 ears) were patients combined with facial nerve aberration, and 25 cases (28 ears) were without facial nerve aberration. The results of imaging examination, pure-tone audiometry, selection of surgical strategy, intraoperative findings and postoperative hearing improvement were summarized and analyzed. The malformations of malleus, incus, stapes, oval window and facial nerve were recorded. Prism 9 software was used to statistically analyze the mean bone conductance and air-bone gap of patients before and after surgery. Results: All the 14 patients (16 ears) with middle ear malformation accompanied by facial nerve aberration and oval window atresia showed poor hearing and no facial palsy since childhood. High resolution CT (HRCT) examination of temporal bone, pure tone audiometry and Gelle test were performed before surgery. The malformations of malleus, incus, stapes, oval window and facial nerve were recorded. Preoperative high-resolution CT (HRCT) examination of temporal bone found 12 ears with 4 or more deformities, accounting for 75.00%, in the group of patients with facial nerve malformation. The preoperative average bone conductive threshold was (15.3±10.4) dB and the average air-bone gap was (46.3±10.6) dB in pure-tone audiometry (0.5, 1, 2, 4kHz). According to the different degrees of facial nerve and ossicle malformation, we performed three different hearing reconstruction strategies for the 14 patients (16 ears) with facial nerve aberration and oval window atresia, including 7 ears of incus bypass artificial stape implantation, 7 ears of Malleostapedotomy (MS) and 2 ears of Malleus-cochlear-prothesis (MCP). After 3 months to 18 months of follow-up, all patients showed no facial paralysis. The postoperative mean bone conductive threshold was (15.7±7.9) dB and air-bone gap was (19.8±8.5) dB. There were significant differences in mean air-bone gap before and after operation (t=7.766, P<0.05), and there was no significant difference between the mean bone conductive threshold before and after surgery (t=0.225, P=0.824). There was no significant difference of mean reduction of air-bone gap between patients with and without facial nerve aberration (t=1.412, P=0.165). There was no significant difference between the three hearing reconstruction strategies. There was no significant displacement of the Piston examined by U-HRCT. Conclusion: For patients of middle ear malformation whose facial nerve cover the oval window partially, incus bypass artificial stape implantation or Malleostapedotomy (MS) can be selected according to the specific condition of auditory ossis malformation, and for patients whose facial nerve completely covers the oval window area, Malleus-cochlear-prothesis (MCP) can be selected. Three types of stapes surgery are safe and reliable for patients with oval window atresia accompanied by facial nerve aberration. There was no significant difference in efficacy between them. Preoperative HRCT assessment of middle ear malformation is effective. There is no significant difference of surgical effect with or without facial nerve aberration. The U-HRCT can be used to evaluate the middle ear malformation before surgery and the Piston implantation status after surgery. Due to the risks of surgery, those who do not want to undergo surgery can choose artificial hearing AIDS, such as hearing aid, vibrating soundbridge, bone bridge or bone-anchored hearing aid.

Isolated oval window atresia (OWA) is a rare cause of congenital conductive middle ear deafness and may be overlooked owing to the normal appearance of the external ear. This anomaly has been previously described, although the published numbers with both imaging and surgical findings are few. Our aim is to correlate the imaging features of OWA with intraoperative findings. This is a single-centre retrospective evaluation of patients who were diagnosed with OWA and who received surgery from January 1999 to July 2006. No new case was diagnosed after 2006 to the time of preparation of this manuscript. High resolution computed tomography (HRCT) imaging of the temporal bones of the patients were retrospectively evaluated by 2 head and neck radiologists. Images were evaluated for the absence of the oval window, ossicular chain abnormalities, position of the facial nerve canal, and other malformations. Imaging findings were then correlated with surgical findings. A total of 9 ears in 7 patients (two of whom with bilateral lesions) had surgery for OWA. All patients had concomitant findings of absent stapes footplate with normal, deformed or absent stapes superstructure and an inferiorly displaced facial nerve canal. HRCT was sensitive in identifying OWA and associated ossicular chain and facial nerve abnormalities, which were documented surgically. OWA is a rare entity that can be diagnosed with certainty on HRCT, best visualised on coronal plane. Imaging findings of associated middle ear abnormalities, position of the facial nerve canal, which is invariably mal-positioned, and associated deformity of the incus are important for presurgical planning and consent.

Oval window atresia (OWA) is a rare otologic condition often associated with a maximal conductive hearing loss, and variable ossicular and facial nerve canal (FNC) anomalies, which have contributed to suboptimal middle ear surgical outcomes. No grading scheme exists to detail the spectrum of associated temporal bone anomalies in OWA; therefore, our objectives were to complete an audiometric and radiographic review to characterize audiometric patterns of hearing loss, and refine the classification system for OWA to determine suitability for middle ear surgery. A retrospective audiometric and radiographic review was conducted at a pediatric tertiary care institution. Patients with OWA identified on temporal bone computerized tomography (CT) scans obtained from 01/2010 to 06/2024 were included. Audiological, radiological, and patient factors were analyzed. Thirty-one patients (48 ears) with OWA were identified. Across frequencies, the air-bone gap decreased significantly as frequency increased (ANOVA with pairwise comparisons, p < 0.001) due to a worsening of bone conduction thresholds and improvement in air conduction thresholds. The FNC was abnormal in 43/48 ears and was determined to overlay the oval window in 6 ears. Additional anomalies included inferiorly displaced, dehiscent, and duplicated canals. Ossicular anomalies were reported in 46/48 ears, and stapedial anomalies were most common. Our findings indicate OWA may manifest audiometrically with consistent and specific hearing loss characterized by a 60-80 dB ABG at lower frequencies that decreases above 2 kHz. CT findings of OWA show considerable variability. We propose a new classification system for OWA based on facial nerve position as this directly influences middle ear surgical feasibility.

Oval window atresia: A novel surgical approach and pathognomonic radiological finding

McRackan, Theodore R.; Carlson, Matthew L.; Reda, Fitsum A.; Noble, Jack H.; Rivas, Alejandro Author Information

A 28-year-old man presented with right-sided facial paralysis that had been worsening over the past eight months. He was initially diagnosed with Bell's palsy and treated with oral steroids and antiviral medication immediately after symptom onset, but experienced minimal improvement. He has a known history of conductive hearing loss in the right ear since age five due to a traumatic tympanic membrane perforation from q-tip use and subsequently underwent tympanoplasty at that time. He denied otalgia, otorrhea, vertigo, or tinnitus. Physical examination showed grade 6/6 paralysis on the right side. Audiogram from two months before presentation ago is shown in Figure 1. What is your diagnosis?Figure 1: Audiogram showing moderate-to-severe conductive hearing loss on the right side. Hearing loss, paralysis.Figure 2: Axial (horizontal) CT of the right temporal bone showing the cholesteatoma involving the middle ear, cochlea, and internal auditory canal. Hearing loss, paralysis.Figure 3: Axial (horizontal) CT of the right temporal bone showing cholesteatoma 1.2 mm above Figure 2 showing the involvement of the tympanic (middle ear) facial nerve by the cholesteatoma. Hearing loss, paralysis.Figure 4: Coronal (vertical parallel to ear) CT of the right temporal bone demonstrating that the cholesteatoma has eroded the tegmen tympani. The cholesteatoma appears to have originated medial to the malleus. Hearing loss, paralysis.Figure 5: Sagittal (vertical parallel to face) CT of the right temporal bone further highlighting the erosion of the tegmen tympani as the cholesteatoma extended medially to the cochlea and internal auditory canal. Hearing loss, paralysis.Figure 6: Sagittal (vertical parallel to face) CT Temporal bone showing the involvement of the cochlea 2 mm medial to the image in Figure 5. Hearing loss, paralysis.DIAGNOSIS: IATROGENIC CHOLESTEATOMA The most concerning aspect of this patient's presentation is the duration of his facial paralysis. Although Bell's palsy is the most frequent diagnosis for facial paralysis, the physician must begin to consider other etiologies and obtain imaging with MRI of the internal auditory canals (IACs) if the paralysis persists beyond six months. The majority of patients with facial paralysis are diagnosed with Bell's palsy, also called idiopathic facial nerve paralysis. By definition, the exact cause of Bell's palsy is unknown; however, it is believed that a large number of cases are due to edema in and around the facial nerve and is caused by the herpes simplex virus (HSV). HSV, which also causes cold sores, has been found to be present within the geniculate ganglion of affected individuals. Viral replication and reactivation within the ganglion are thought to cause edema and subsequent compression of facial nerve fibers, resulting in blockage of electrical conduction and subsequent facial paralysis. The surrounding bony architecture of the facial nerve helps to explain this phenomenon. As it courses through the labyrinthine segment of the temporal bone (the narrowest portion of the fallopian canal measuring approximately 0.68 mm), the facial nerve is completely surrounded by bone, and therefore vulnerable to compression in the event of swelling. The extent of nerve injury depends on both the degree of inflammation and how quickly treatment with steroids and antivirals can be given to reduce swelling. In cases of mild edema, there is transient compression and blockage of nerve conduction until the inflammation subsides. However, in more severe cases the nerve fibers may be crushed and rapidly degenerate. In these cases, axon regeneration usually occurs, but the new nerve fibers may not reach the intended target muscles. This results in synkinesis, in which voluntary movement in one facial muscle group causes involuntary activity of another. For example, a patient may experience involuntary blinking when trying to smile. In the case of this patient, we obtained a CT scan of the temporal bones given the history of conductive hearing loss and previous surgery (Figs. 2, 3, 4, 5). On the right side, we see bony erosion with soft tissue opacification within the petrous and mastoid temporal bone segments, including regional involvement of the labyrinthine and tympanic segments of the facial nerve, basal turn of the cochlea, vestibule, IAC, tegmen tympani, and middle ear cavity including the ossicles. Though initially treated for Bell's palsy, our patient was ultimately diagnosed with a middle ear cholesteatoma that invaded the skull base and involved the facial nerve. The diagnosis was confirmed surgically. Cholesteatomas are benign masses comprised of abnormal squamous epithelium within the temporal bone. Over time, these masses can grow large enough to cause local bony destruction with surrounding inflammation and granulation tissue. Cholesteatomas are often classified into congenital and acquired types (primary or secondary). In the primary acquired type, cholesteatomas typically arise in the setting of chronic tympanic membrane (TM) retraction. Alternatively, secondary acquired cholesteatomas occur in the setting of TM perforation with epithelial migration into the middle ear space. Given the patient's history of q-tip injury and subsequent surgery, the cholesteatoma was most likely caused by traumatic implantation of squamous epithelium or iatrogenic, i.e., caused by the surgeon not removing or implanting squamous epithelium from the middle ear. Facial nerve palsy due to cholesteatoma has been rarely reported in the literature.1 While the mechanism by which cholesteatoma causes facial nerve palsy remains unclear, several theories have been proposed. The first hypothesis is that direct compression by the cholesteatoma is responsible for causing nerve edema and subsequent ischemia. A second hypothesis is that direct contact between the cholesteatoma and facial nerve promotes an inflammatory reaction that leads to injury. This theory is supported by histological studies showing degeneration of the epineurium in facial nerve segments exposed to cholesteatoma or granulation tissue.2 A third hypothesis is that nerve injury is mediated by neurotoxic or enzymatic substances secreted by the cholesteatoma, although the significance of these factors remains controversial.3 It is important to accurately diagnose and treat cholesteatomas, as they have a strong propensity to become infected and erode through local bony structures.4 The infections and associated pathogens in cholesteatoma can be especially hard to eradicate as they are frequently polymicrobial and resistant to antibiotics. Skull base invasion of cholesteatomas carries an increased risk of deafness, facial paralysis, and intracranial complications given their location. In this patient, we see the cholesteatoma is already eroding the cochlea, creating an increased likelihood of sensorineural hearing loss in the right ear. After evaluating the extent of the disease on CT scan, surgical treatment is undertaken with the goals of removing all of the cholesteatoma and repairing damaged structures when possible. Various surgical approaches can be used, depending on the involved structures as well as surgeon comfort level. In this patient, a right middle cranial fossa or translabyrinthine approach could be undertaken. Generally, when the hearing is intact, the best approach is the middle cranial fossa. The translabyrinthine approach is reserved for non-serviceable hearing patients. If the facial nerve function does not return, the patient may receive a hypoglossal-facial jump graft. In the future, a medical device in development may allow restoration of function for the patient.5-6 BONUS ONLINE VIDEOS: VISUAL DIAGNOSIS Read this month's Clinical Consultation case, then watch the accompanying videos from Hamid R. Djalilian, MD, to review the patient's imaging for yourself. Video 1. Axial (horizontal) CT of the right temporal bone showing the extent of the cholesteatoma in the axial plane and involvement of tympanic facial nerve and geniculate ganglion. Video 2. Coronal (vertical parallel to ear) CT of the right temporal bone showing the extent of the cholesteatoma in the coronal plane and invasion of the tegmen and IAC. Video 3. Sagittal (vertical parallel to face) CT of the right temporal bone showing the extent of the cholesteatoma in the sagittal plane and invasion of the cochlea. Video 4. Axial (horizontal) CT of the left temporal bone showing the normal anatomy of the facial nerve in the axial plane. Video 5. Coronal (vertical parallel to ear) CT of the left temporal bone showing the normal anatomy of the tegmen tympani. Video 6. Sagittal (vertical parallel to face) CT of the left temporal bone showing the normal cochlear anatomy in the sagittal plane. Watch the patient videos online at thehearingjournal.com

Symptoms: Sudden Sensorineural Hearing Loss and Aural Fullness

THE INCIDENCE of trauma to the temporal bone is increasing because of the rising number of automobile accidents. Blows to the head can produce damage within the temporal bone which is difficult to visualize on the conventional radiographic examination of the skull. Using thin-section tomography, however, one can visualize the structures within the temporal bone to identify ossicular dislocation, fractures across the facial nerve canal, and stenosis of the external auditory canal. It is important to identify and localize the damage, since many of these injuries can be corrected surgically. Tomography Technic and Normal Anatomy Thin-section tomography is necessary for the radiological diagnosis of fractures within the temporal bone and dislocation of the auditory ossicles. The pluri-directional tomograph (Philip's Universal Polytome) allows sections 1 mm in thickness. The hypocycloidal movement of the tube results in more efficient blurring of superimposed objects, with resultant finer details of the layer in focus. The frontal and lateral projections are best suited for the middle and inner ear structures, including the malleus and incus. The stapes is seen only in the 20° oblique frontal projection (9). Pathology Two types of fractures occur in the temporal bone: longitudinal and transverse. The longitudinal fracture shown in Fig. 1 is four times more common than the transverse and results from force applied either to the temporoparietal region or to the mandibular condyle. This fracture extends medially along the bony external canal, and at the middle ear turns either anteriorly to end in the region of the carotid canal or posteriorly to end in the mastoid region. The clinical symptoms of a longitudinal fracture are a ruptured drum and bleeding into the middle ear and external canal. If the dura overlying the tegmen is lacerated, cerebrospinal fluid will drain into the external canal. Facial nerve paralysis occurs in 10 to 40 per cent of these patients, but 75 per cent recover spontaneously. They often have a conductive hearing loss; a sensorineural loss may result from labyrinthine concussion. A transverse fracture crosses perpendicularly to the long axis of the petrous pyramid. This fracture is the result of a force applied to either the occipital or the occipitomastoid region. The fracture proceeds through the labyrinthine capsule and may cross the facial nerve canal. Clinically, facial nerve palsy occurs in 30 to 50 per cent of the patients. Total nerve deafness and vertigo are common. Blood or cerebrospinal fluid can leak through the fracture into the middle ear cavity but may go undetected because of an intact ear drum. Rarely, the longitudinal and transverse fractures may be combined.

The difficulty of cochlear implantation in patients with congenital microtia is usually increased due to the vague anatomical marks and facial nerve malformation. The common types of facial nerve malformation include facial nerve bony cover loss, aberrant position, and bifurcation malformation. Bifurcation malformation may obscure the oval window, press against stapes, and bifurcate in the vestibular window while obscuring the round window. It is important to correctly identify the facial nerve and choose a reasonable surgical approach to avoid postoperative complications. This article describes a case of profound sensorineural hearing loss due to facial nerve malformation in our institution. The patient underwent cochlear implantation through the retro-facial approach. There was no facial nerve injury or dysfunction symptoms such as facial paralysis and hemifacial spasm 2 years after the operation, and the cochlear implant works well. The score of the categories of the auditory performance（CAP） questionnaire was 7, and the score of the speech intelligibility rating（SIR） questionnaire was 4. When the round window cannot be exposed through the facial recess approach during surgery, the retro-facial approach is a feasible method. To avoid facial nerve injury, a thin-section CT of the temporal bone should be performed before the middle and inner ear surgery for patients with facial nerve malformation, and the intraoperative facial nerve monitor should be used to clarify the course of the facial nerve to avoid injury.

Symptom: Unilateral Hearing Loss

Symptom: Postauricular Mass