Endoscopic Incudo-Malleolar Arthrodesis: A New Surgical Treatment for Incudo-Malleolar Subluxation.

To review outcomes of stapes surgery in patients with concurrent otosclerosis and superior semicircular canal dehiscence. Retrospective case series. Tertiary referral center. Patients with concurrent otosclerosis and superior canal dehiscence, confirmed by computed tomography (CT) imaging. Stapes surgery for conductive hearing loss. Postoperative air-bone gap (ABG), as well as the number of patients in whom surgery was deemed successful (postoperative ABG <10 dB HL). Five patients with superior canal dehiscence and concomitant otosclerosis who underwent surgical repair were identified. Mean preoperative ABG was 29.0 ± 6.4 dB HL. Mean postoperative ABG was 13.0 ± 13 dB HL. Three patients (60%) had a successful outcome, defined as postoperative ABG less than 10. One patient experienced unmasking of superior canal dehiscence vestibular symptoms. Patients with concurrent otosclerosis and superior canal dehiscence appear to have a lower likelihood of successful hearing restoration following stapes surgery. Patients should be counseled accordingly. Routine preoperative CT imaging before stapes surgery may be helpful to identify patients at risk for poor outcomes.

Is Preoperative Computed Tomography Necessary or Useful for Primary Stapes Surgery?

The middle fossa floor lacks reliable surface landmarks. In cases of superior semicircular canal dehiscence (SSCD), multiple skull base defects may be present, further confounding the location of the labyrinth. Misidentification of the SSCD during surgery may lead to treatment failure or sensorineural hearing loss. Anecdotally, the authors have observed the distance from the lateral edge of the craniotomy to the SSCD to be consistently 1 inch. Herein, we present radiologic evidence of this practical and clinically useful relationship. All patients at two tertiary care academic referral centers with high-resolution temporal bone computed tomography (CT) evidence of SSCD were retrospectively reviewed. Review of high-resolution temporal bone CT. The horizontal distance from the outer cortex of the squama temporalis immediately superior to the bony external auditory canal (approximating lateral edge of craniotomy) to the SSCD was measured in the coronal plane by two independent reviewers. A total of 151 adult ears with SSCD were analyzed. A Shapiro-Wilk goodness-of-fit test confirmed that measurements were normally distributed. Pearson inter-rater correlation was 0.95, confirming very strong agreement. The mean distance between the outer cortex of the squama temporalis and SSCD was 25.9 mm, or 1.02 inches. Sixty-eight percent of the SSCD population would fall between 0.92 and 1.12 inches and 95% would lie between 0.83 and 1.21 inches. The horizontal distance from the outer cortex of the squama temporalis to the SSCD consistently approximates 1 inch. This easily remembered distance can aid surgeons in locating or confirming the SSCD during middle fossa surgery.

The study of the association between superior semicircular canal and other dehiscences in the temporal bone. We have studied computed tomography of radiologically diagnosed people with superior or posterior semicircular canal dehiscences, in four health centres. In addition, we have studied one isolated human temporal bone, one skull and one cadaver head belonging to the collection of the Department of Human Anatomy and Histology of the University of Zaragoza that had dehiscence in the superior semicircular canal. The most frequent association that we observed was between superior semicircular canal dehiscence and tegmen tympani dehiscence (37.33%). Three cases (two clinical cases and one isolated temporal bone) showed multiple associated dehiscences (tegmen tympani, mastoid antrum, posterior semicircular canal, internal auditory canal, glenoid cavity, tympanum bone and geniculate ganglion) associated with superior semicircular canal dehiscence. When the superior semicircular canal dehiscence is associated to other in the petrous bone (tegmen tympani, mastoid antrum, posterior semicircular canal, internal auditory canal) could be grouped into the same syndrome called "otic capsule syndrome", since they have the same origin and common aetiology (otic capsule).

Background and Objectives This study aimed to analyze the prevalence of superior semicircular canal dehiscence (SSCD) in the coronal images of high-resolution temporal bone computed tomography (TBCT) and to evaluate the diagnostic accuracy of coronal images for SSCD syndrome. Subjects and Method We retrospectively reviewed high-resolution TBCT scans of 217 patients (434 ears) with SSCD due to various causes. The dehiscence ratio (slices showing dehiscence/total slices showing the superior semicircular canal) in the coronal images of TBCT was calculated, and the optimal cutoff value for the diagnosis of SSCD syndrome was determined using the receiver operating characteristics (ROC) curve. Results Of the 434 ears, 64 (14.7%) presented SSCD in more than one slice of the coronal images of TBCT, but only three patients (0.7%) were confirmed with SSCD syndrome. Based on the ROC curve analysis for the dehiscence ratio of 64 ears, the optimal cutoff value for the diagnosis of SSCD syndrome was 0.67 with 100% sensitivity and 90.2% specificity. Conclusion The majority of cases diagnosed with SSCD syndrome using the coronal images of TBCT were asymptomatic or false-positive. The dehiscence ratio in the coronal images of TBCT combined with a typical symptom can be a highly sensitive and specific diagnostic tool for SSCD syndrome. Key words: Computed tomography ㆍ ROC curve ㆍ Semicircular canals

The inner ear is composed of a fluid-filled sac enclosed by a rigid bony capsule.1 The tympanic membrane and ossicles of the middle ear act as a transformer amplifying airborne sound and efficiently transferring it to the inner ear fluid. There normally are two windows in the bony capsule, the oval and round windows, which direct the forces associated with sound waves along the spiral basilar membrane (figure, A). Because of the rigid bony capsule, the vestibular part of the labyrinth is unaffected by sound or pressure changes in the middle ear and CSF. However, a break in the bony capsule renders the vestibular labyrinth sensitive to sound and pressure changes. Figure. Mechanism of symptoms and signs with superior semicircular canal dehiscence syndrome. (A) Schematic drawing of inner ear. There are normally two windows in the bony capsule—the oval window (filled by the stapes foot plate) and the round window. A third window in the bony wall of the superior semicircular canal leads to vertigo and nystagmus with loud sounds or pressure changes in the middle ear or CSF (B and C). If the window is large enough, …

To investigate the effect of semicircular canal dehiscence (SCD) on surgical outcomes in patients with otosclerosis. Case series with chart review. Tertiary referral center. Eighteen patients were identified with concomitant, clinically suspected otosclerosis and radiographic SCD. Eight patients underwent primary stapes surgery, 2 underwent revision stapes surgery, 6 were advised against surgery, and 2 patients were evaluated after unsuccessful stapes surgery done elsewhere and had worsened hearing or unmasked third-window symptoms. Some patients were not offered stapes surgery due to presumed higher risk.Intervention(s):Review audiometric, and radiographic evaluations of patients who were diagnosed with both otosclerosis and SCD.Main outcome measure(s):Preoperative and postoperative audiometry, radiographically measured approximate dehiscence area (ADA), and symptoms in patients with otosclerosis and semicircular canal dehiscence were evaluated. Six of 8 (75%) primary stapedotomy patients had closure of the air-bone gap (ABG) to <10dB, while 1 patient had >20dB ABG. Both revision stapedotomy patients had >20dB ABG postoperatively. No patients operated by the authors reported unmasking of third-window symptoms after stapes surgery. ADA was not significantly different in patients in the unoperated versus primary/revision stapes surgery group. One patient who had a present cVEMP threshold did not close their ABG after stapes surgery, whereas 2 patients with absent cVEMP thresholds did. In select patients, stapes surgery can result in improved hearing when otosclerosis and SCD coexist. Measurements of dehiscence area were not shown to predict surgical outcomes. CT imaging combined with VEMP testing appear to be valuable tools to assess risk of stapes surgery.

Objective: To investigate the clinical features of patients with congenital atresia of the oval window (CAOW). Methods: A retrospective analysis was conducted on 7 cases (8 ears) of surgically confirmed CAOW treated at our department from July 2018 to July 2024. Among the cases, 1 patient had bilateral CAOW, and 4 patients had unilateral CAOW combined with other types of ossicular chain malformations in the contralateral ear. We collected and analyzed the clinical data, audiological features, and temporal bone HRCT results of all patients. Results: The 7 patients were diagnosed at ages ranging from 8 to 19 years, with a mean age of (13.2±6.9) years. None of the patients exhibited significant auricular deformities. All presented with conductive hearing loss or mixed hearing loss predominantly of the conductive type, with an intact tympanic membrane. The diagnosis of CAOW was confirmed via endoscopic tympanotomy, revealing a concave oval window area on the medial wall of the tympanic cavity, sealed by a bony plate. All 8 ears exhibited additional ossicular chain deformities. Stapes absence was present in all 8 ears. Partial absence of the incus long process was observed in 3 ears, while, abnormal bony connections between the incus long process and the promontory were seen in 4 ears, 1 ear had a short malleolar handle, 1 ear had a smaller than normal malleus volume. In addition, facial nerve deformities were found in 6 ears, with 4 ears showing bifurcation of the facial nerve and 2 ears showing facial nerve obscuration of the oval window. Pure-tone audiometry revealed that 62.5% (5/8 ears) of patients had air conduction (AC) thresholds≥60 dB preoperatively, with a mean pure-tone average (PTA) of (69.0±11.8) dB HL and a mean air-bone gap (ABG) of (52.0±7.0) dB. The mean AC threshold and ABG were higher in the low-frequency (125-1 000 Hz) range compared to the high-frequency (2 000-8 000 Hz) range (both P<0.05). Preoperative HRCT showed abnormalities in all patients, with 7 ears being diagnosable as CAOW. Although the remaining 1 ear could not be diagnosed as CAOW, stapes and incus long process absence were detected. Conclusion: CAOW is rare in clinical, as the patients with non-progressive conductive hearing loss (AC≥60 dB, ABG≥50 dB) since childhood, intact tympanic membrane without malformations of auricle and external auditory canal, and thick bony plate covered the oval window of the HRCT imaging, CAOW should be highly suspected, which could be confirmed by the exploratory tympanotomy.

The leaking labyrinthine lesion resulting from direct force through the auditory canal: report of five cases

This report describes a novel case in which superior canal dehiscence syndrome was unmasked by successful stapes surgery for otosclerosis. Case report and literature review regarding superior canal dehiscence syndrome. Superior canal dehiscence syndrome is a rare but well described condition in which audiovestibular symptoms are caused by noise or straining. A dehiscence of the superior semicircular canal in the floor of the middle cranial fossa is responsible, and acts as a 'third window' into the inner ear. A patient with confirmed otosclerosis underwent second-side stapedotomy, with good audiometric outcomes. Unfortunately, surgery was complicated by immediate post-operative vertigo and persistent auditory symptoms. A diagnosis of superior canal dehiscence syndrome was eventually made, on the basis of low threshold vestibular evoked myogenic potentials and characteristic computed tomography findings. Superior canal resurfacing resulted in complete resolution of symptoms. The otosclerotic focus in the oval window prevented the development of symptoms from this patient's superior canal dehiscence syndrome. Surgical stapedotomy created a third window and resulted in immediate post-operative imbalance and auditory symptoms. The diagnosis of superior canal dehiscence syndrome should be considered in patients with persistent audiovestibular symptoms after stapes surgery. High resolution computed tomography of the temporal bone and vestibular evoked myogenic potential testing, if available, are the investigations of choice in confirming the diagnosis.

The etiology of superior canal dehiscence (SCD) is controversial. An embryological perspective suggests that SCD may occur through the failure of postnatal bone formation over the superior semicircular canal (SC), whereas an acquired theory suggests that trauma or pressure from the overlying temporal lobe could break or gradually thin the SC. We infer the etiology of SCD by comparing the thickness of the bony otic capsule of the unaffected side of SCD patients with that of non-SCD participants. Twelve SCD patients (13 SCD ears and 11 normal ears) and 34 age-matched controls (68 ears) were included. The control group was subdivided into an aerated group (49 ears) and a nonaerated group (19 ears), as defined by the presence of air cells above the SC. A high-resolution temporal bone CT was performed in all participants. The thicknesses of the SC, horizontal canal (HC) and posterior canal (PC) of the unaffected ears of SCD patients were compared with those of the controls. The SC of the unaffected side in the SCD group (n = 11, 0.41 ± 0.23 mm) was significantly thinner than the one in the control group (n = 68, 0.64 ± 0.21 mm, p = 0.002). The HC and PC were also thinner in the SCD group (n = 24, 0.58 ± 0.11 and 1.39 ± 0.31 mm, respectively) than in the controls (0.70 ± 0.08 and 1.61 ± 0.32 mm; p < 0.0001 and p = 0.005, respectively). The SC, HC and PC thicknesses were also compared between the aerated and nonaerated ears within the control group. The SC was significantly thicker in the aerated group (0.73 ± 0.14 mm) than in the nonaerated group (0.60 ± 0.23 mm; p = 0.046); however, no significant difference was observed for the HC and PC thickness (aerated group, n = 49, 0.72 ± 0.07 and 1.67 ± 0.34 mm; nonaerated group, n = 19, 0.70 ± 0.09 and 1.59 ± 0.34 mm; p = 0.350 and p = 0.428, respectively). The bony otic capsule was significantly thinner in the SCD patients than in the controls. However, even within unaffected individuals, SCs lacking overlying air cells were also thinner than those with overlying air cells. These results suggest that both embryological and acquired factors affect the occurrence of SCD.

Superior semicircular canal dehiscence (SSCD) causing conductive hearing loss with present reflexes is a known reason for stapes surgery failure. However, concomitant SSCD and otosclerosis occur rarely. We present a case series of SSCD diagnosed in positively identified otosclerosis patients. Retrospective review of clinical case series in two tertiary-referral neurotologic practices was performed. Clinical histories, operative findings, audiograms, and computed tomography (CT) images were reviewed for patients diagnosed with both SSCD and otosclerosis. Patients with present stapedial reflexes were excluded. Comprehensive literature review was performed. Four cases were identified. Three reported improved hearing with partial or complete closure of the air-bone gap (ABG), including one patient with far-advanced otosclerosis. One patient had no improvement in pure tone average or ABG. One patient reported worsening of preoperative autophony and pulsatile tinnitus, but none developed new postoperative third-window symptoms. CTs demonstrated both SSCD and otosclerosis. Failure to close the ABG in patients with positively identified otosclerosis intraoperatively may be due to SSCD as an occult concomitant diagnosis. SSCD should be considered as a possible cause of persistent conductive hearing loss after stapes surgery. 4 Laryngoscope, 130:1023-1027, 2020.

Tragal perichondrium is a widely used tissue seal in the oval window following stapes surgery. Autogenous and easily accessible, it is a suitable substance to cover the vestibule in total stapedectomy, and to seal around the prosthesis in small-fenestra stapedotomy. The incidence of complications from the use of perichondrium in this manner is exceedingly low. We report a case where tragal perichondrium in the oval window resulted in the proliferation of cartilage. The cartilage displaced the stapes prosthesis, resulting in a conductive loss. Although the chondrogenic potential of perichondrium is known, we are not aware of other reports implicating this as a cause of failure in stapes surgery. The pertinent clinical and experimental literature regarding chondrogenesis is reviewed. This information suggests that the formation of cartilage from perichondrium in the oval window might be influenced by mechanical trauma and tissue orientation.

The aim of the study was to find out the reasons of the recurrent or persisting hearing loss after previous stapes surgery indicated for otosclerosis. Revision stapes surgery is a relatively safe surgical method. Recurrent or persisting conductive hearing loss is commonly caused by prosthesis dislocation and adhesions in the oval window. Hearing loss is directly proportional to the number of previous operations. Retrospective analysis of 48 patients after revision stapes surgery was done over a period of 4 years (2005-2008). Improvement of the hearing and the reasons of a previous surgery failure were studied. RESULTS were compared to the other studies. The main reason of the failed surgery was adhesions and dislocation of the prosthesis. The mean postoperative air-bone gap was 12.0 dB. A mean postoperative air-bone gap closure within 10 dB occurred in 24 cases (55.8 %), between 11-20 dB occurred in 11 cases (25.6 %) and above 20 dB in 8 cases (18.6 %). The original prosthesis was replaced with a new one in 41 (95.3 %) cases. In 2 cases (4.7 %), previous prostheses were left in place and fixed by a ionomer glass cement to the long process of incus. Revision stapes surgery is a relatively safe surgical procedure allowing to improve hearing. The number of previous stapes surgery deteriorates hearing (p < 0.05) (Tab. 4, Ref. 20).

Cases historically presumed to be perilymphatic fistula of the round and/or oval window may be cases of third window syndrome due to inner ear dehiscence. Perilymphatic fistula (PLF) is a condition where a pathologic external connection of the perilymphatic space is present, often with an associated otic capsule or stapes defect. Recently, it has become evident that otic capsule defects in locations that lack perilymphatic fluid leak can cause clinical symptoms. Such clinical entities are deemed "third window" syndromes-among which superior semicircular canal dehiscence is the most common. Human temporal bone specimens underwent histopathologic study of cases previously suspected to have PLF at the oval or round window. These specimens were further scrutinized for the presence of an alternate site of inner ear dehiscence that may have potentially caused a third window syndrome. Thirty-one out of 34 of the cases (61 ears) from a previously published study on PLF were reviewed. Altogether, dehiscences were noted at the following locations: cochlea-facial (11), superior semicircular canal (5), endolymphatic sac-jugular bulb (4), cochlea-internal auditory canal (3), posterior semicircular canal (2), and an enlarged/patent cochlear aqueduct (2). One patient with a histologic dehiscence had an audiogram consistent with third window syndrome. The findings suggest that many clinical cases historically presumed to be PLF of the round and/or oval window may, in fact, be cases of third window syndrome due to inner ear dehiscence with pathology at sites other than the oval or round windows.