Pathologic Findings of the Cochlea in Labyrinthitis Ossificans Associated with the Round Window Membrane

Cochlear Implantation by Veria Technique in Abnormal Cochlea: Our Experience

This study describes the clinical profile, operative findings, surgical technique, type of implant and complications encountered in implantation of abnormal cochlea by the transcanal (veria) technique in a tertiary care centre. This is a retrospective study done amongst 337 patients who underwent cochlear implantation by veria technique between January 2013 to August 2023. Based on pre-operative imaging with high-resolution computed tomography and magnetic resonance imaging the cochleovestibular malformations in this study were classified according to Sennaroglu classification and the cochlear ossification was graded from I to IV. Amongst the 337 patients who underwent cochlear implantation during the study period there were 79 cases (23.4%) with abnormalities of cochlea. This included 45 patients (13.4%) with congenital malformations, 20 patients (5.9%) with cochlear fibrosis and 14 patients (4.2%) with cochlear ossification. The commonest cochlear malformation was Incomplete Partition 2 which was present in 21 patients (46.7%). The other common malformations were cochlear hypoplasia (31.1%), Incomplete Partition 1(13.3%) and common cavity (8.9%). Out of the 20 patients with cochlear fibrosis, 17 patients had fibrosis only in the basal turn. Out of the 14 patients with cochlear ossification 8 patients (57.1%) had a grade 1 ossification, 2 patients (14.3%) had a grade 2 ossification and 4 patients (28.6%) had a grade 3 ossification. One of the patients required re-exploration for correcting the placement of electrode. The type of implant were chosen depending on individual malformation or length of ossification and fibrosis. In the past, inner ear anomalies were considered as a contraindication for cochlear implantation however it is now possible to implant most of these abnormal cochlea by careful planning, a modification of the surgical technique and the type of electrode used.

Cochlear implantation for rare Streptococcus suis meningitis with hearing loss

OBJECTIVES

This study aimed to explore the diagnostic sensitivity of 3D heavily weighted T2-weighted MRI (T2MRI) and high-resolution computed tomography (HRCT) in patients with cochlear fibrosis associated with Streptococcus suis (S. suis) meningitis and the practicality of Cochlear implantation (CI) treatments.

METHODS

Between January 2020 and December 2022, we enrolled four patients with rare cochlear S. suis meningitis with associated hearing loss despite aggressive or non-aggressive follow-up antibiotic treatment. Clinical imaging data, surgical performances and post-surgical-electrode impedance were evaluated.

RESULTS

Combined with HRCT and T2MRI, the cochlea had varying degrees of fibrosis and ossification in different cases. However, the electrodes were successfully and wholly inserted after intraoperative removal of the ossified and fibrotic foci. Post-surgical electrode impedance values of MP1 + 2 mode were normal in all 4 cases at initial activation.

CONCLUSION

In patients with S. suis meningitis and associated cochlear fibrosis, T2MRI examination of the inner ear was more sensitive than HRCT. This research highlights the feasibility of CI treatment in S. suis meningitis patients with severe cochlear fibrosis.

Cochlear Implants after Meningitis and Otosclerosis: A Comparison between Cochlear Ossification and Speech Perception Tests

(1) Background: Performance after Cochlear Implantation (CI) can vary depending on numerous factors. This study aims to investigate how meningitis or otosclerosis can influence CI performance. (2) Methods: Retrospective analysis of CI performance in patients with etiological diagnosis of meningitis or otosclerosis, comparing the etiologies and analyzing the image findings, along with electrode array insertion status and technique. (3) Results: Speech recognition in CI patients with otosclerosis improves faster than in patients with meningitis. Other features such as radiological findings, degree of cochlear ossification, surgical technique used and total or partial insertion of electrodes do not seem to be directly related to speech recognition test performance. (4) Conclusions: Patients should be warned that their postoperative results have a strong correlation with the disease that caused their hearing loss and that, in cases of meningitis, a longer duration of speech-language training may be necessary to reach satisfactory results.

The Conundrum of Labyrinthitis Ossificans: An Etiology-Based Case Comparison and Review of Literature

Labyrinthitis ossificans is the formation of pathological new bone within the membranous labyrinth of the inner ear due to various local and systemic pathologies. Most commonly it occurs as a sequelae of meningitis spreading to the labyrinth, from the subarachnoid space via the cochlear aqueduct and the internal auditory canal. We are comparing three different etiological presentations of labyrinthitis ossificans; namely, tympanogenic, meningitic, and traumatic, together with their management in the light of recent advances.

Cochlear Implant Induced Labyrinthine Ossificans in Mondini Malformation: A Case Series

Cochlear implantation is relatively a safe procedure with a favorable outcome. Labyrinthine ossification is one of the rare complications that has been observed in some occasions post-cochlear implantation. This paper report two cases of Mondini inner ear malformation cochlear implant failure associated with labyrinthine ossification, mandating revision surgery, and a literature review focusing on the reported cases, risk factors, surgical and non-surgical measures to mitigate this complication and to improve overall cochlear implant outcomes.

Histopathology of Labyrinthitis Ossificans From an Intralabyrinthine Surgical Specimen

OBJECTIVE

Histologic characterization of labyrinthitis ossificans (LO) has mostly been limited to postmortem samples. In this report, we describe the histology of LO from a surgical specimen obtained from a patient undergoing labyrinthectomy with simultaneous cochlear implantation.

PATIENT

A 38-year-old woman initially presenting to the emergency room with acute vertigo, left-sided hearing loss, tinnitus, and aural fullness.

INTERVENTIONS

Contrast-enhanced magnetic resonance imaging (MRI) and computerized tomography (CT) were performed for the patient before labyrinthectomy and cochlear implantation. Audiometric testing was performed before and after surgical intervention. Histologic analysis was performed on a specimen obtained from the left lateral semicircular canal (SCC) during surgery.

MAIN OUTCOME MEASURES

Preoperative CT and MRI findings, preoperative and postoperative hearing thresholds via air conduction and bone conduction, hematoxylin and eosin (H&E) stain of the surgical sample, and CD45 immunostain of the surgical sample.

RESULTS

Preoperative CT and MRI confirmed the diagnosis of isolated LO of the left lateral SCC. Audiometric testing revealed significant improvement in hearing after labyrinthectomy and cochlear implantation. H&E stain demonstrated fibrosis and ossification in the left lateral SCC, and CD45 immunostain was negative.

CONCLUSIONS

Histopathology of LO based on a surgical sample is comparable to heterotopic ossification (HO) seen in other human tissue. Given the similarities between LO and HO, agents effective in preventing HO may have utility in preventing LO.

[A case of obliteration of a round window in otosclerosis]

The article presents a brief review of the literature on the anatomy and physiology of the round window (RW) niche, the causes of occlusion, the diagnosis of this pathology, the features of auditory disorders and tactics when it is detected in patients with otosclerosis (OS). A clinical case of diagnosis and effective surgical treatment for obliteration of RW in a patient with advanced OS, which occurred in 2019 in 0.7% of cases, is described. Removal of RW niche obliteration was carried out with a curette and microcresis by smoothing the canopy over RW until partial visualization of the secondary membrane. It was this stage of the operation that made it possible to restore the normal hydrodynamics of the inner ear fluids and contributed to a functional result. Thus, the diagnosis of RW obliteration in patients with OS is difficult, but possible when using computed tomography of the temporal bones and assessing the mobility of the RW membrane or analyzing changes in hearing at the end of the operation, if it is performed under local anesthesia. The simultaneous performance of stapedoplasty and the removal of bone obliteration of RW makes it possible to safely achieve functional rehabilitation in patients with OS.

Otopathologic Analysis of Patterns of Postmeningitis Labyrinthitis Ossificans

OBJECTIVE

Labyrinthitis ossificans (LO) may occur following meningitis and, in cases where cochlear implantation is indicated, complicate electrode insertion. LO is critical to identify for successful cochlear implantation, and histopathology is more sensitive than imaging for identification of LO. Herein we utilize otopathologic techniques to study the timing and location of intracochlear tissue formation following meningitic labyrinthitis (ML).

STUDY DESIGN

Retrospective review.

SETTING

Academic institution.

METHODS

Temporal bone specimens with a history of bacterial ML were histologically evaluated. The location and extent of intracochlear tissue formation within the scala tympani (ST) and scala vestibuli (SV) were graded, and spiral ganglion neurons were counted.

RESULTS

Fifty-one temporal bones were identified: 32 with no intracochlear tissue formation, 9 with fibrosis alone, and 10 with LO. Fibrosis was identified as early as 1.5 weeks after ML, while ossification was found only in specimens that survived multiple years after ML. All LO cases showed ossification of the ST at the round window membrane (RWM) with continuous extension throughout the basal turn. Extent of SV ossification correlated with that in the ST but showed frequent isolated distal involvement of the cochlea. Spiral ganglion neuron counts were lower than those in age-matched controls.

CONCLUSION

In this human temporal bone study, we found that postmeningitic LO results in ossification at the RWM with continuous extension into the ST of the basal turn and variable involvement of the SV. Identification of a patent basal turn beyond RWM ossification of the ST should permit full electrode insertion.

LEVEL OF EVIDENCE

Retrospective review.

Anatomical landmarks for cochlear implantatıon in ossifıed cochleas

PURPOSE

In this study, we aimed to introduce the facial nerve as a new anatomical landmark which can be used in ossified cochleas during cochlear implantation. We also set out to define a safe line to preserve the internal auditory canal (IAC) while drilling the basal turn of the cochlea.

METHODS

Thirty patients who had temporal computed tomography (CT) were studied. The distances from the facial nerve and the round window to the IAC, carotid artery, and jugular bulb were measured in the reformatted CT images. We have created a line in the direction of the stapedial tendon from the round window to the IAC and called it ROWIAC (Round window-IAC) line. We have investigated whether this line intersects the IAC and measured the distances from this line to the IAC.

RESULTS

Fifty-four temporal CT scans were included to the study. The mean distances from the facial nerve to the IAC, carotid artery, and jugular bulb were 8.8 ± 0.9, 15.0 ± 2.0, and 12.2 ± 2.9 mm, respectively. The mean distances from the round window to these structures were 3.8 ± 0.7, 9.4 ± 2.2, and 8.3 ± 2.9 mm, respectively. ROWIAC line did not intersect the IAC in any of the patients. The mean distance between this line and the IAC was 0.8 ± 0.4 mm.

CONCLUSION

We propose that facial nerve and ROWIAC line can be used as potential landmarks during cochlear implantation in ossified cochleas to protect the adjacent neurovascular structures.

Histopathological changes to the peripheral vestibular system following meningitic labyrinthitis

OBJECTIVE

While cochlear ossification is a common sequalae of meningitic labyrinthitis, less is known about the effects of meningitis on peripheral vestibular end organs. Herein, we investigate histopathologic changes in the peripheral vestibular system and cochlea in patients with a history of meningitic labyrinthitis.

METHODS

Temporal bone (TB) specimens from patients with a history of meningitis were evaluated and compared to age-matched controls. Specimens were evaluated by light microscopy and assessed for qualitative changes, including the presence of vestibular and/or cochlear endolymphatic hydrops, presence and location of inflammatory cells, new bone formation, and labyrinthitis ossificans; and quantitative changes, including Scarpa's ganglion neuron (ScGN) and spiral ganglion neuron (SGN) counts.

RESULTS

Fifteen TB from 10 individuals met inclusion and exclusion criteria. Presence of inflammatory cells and fibrous tissue was found in 5 TB. Of these, evidence of labyrinthitis ossificans was found in 2 TB. In the peripheral vestibular system, mild to severe degeneration of the vestibular membranous labyrinth was identified in 60% of cases (n = 9 TBs). There was a 21.2% decrease (range, 3%-64%) in the mean total count of ScGN in patients with meningitis, compared to age-matched controls. In the cochlea, there was a 45% decrease (range, 25.3%-80.9%) in the mean total count of SGN compared to age-matched controls (n = 14 TBs).

CONCLUSIONS

Otopathologic analysis of TB from patients with a history of meningitic labyrinthitis demonstrated distinct peripheral vestibular changes. Future research may help to delineate potential mechanisms for the observed otopathologic changes following meningitis.

LEVEL OF EVIDENCE

N/A.

The Forgotten Second Window: A Pictorial Review of Round Window Pathologies

The round window serves to decompress acoustic energy that enters the cochlea via stapes movement against the oval window. Any inward motion of the oval window via stapes vibration leads to outward motion of the round window. Occlusion of the round window is a cause of conductive hearing loss because it increases the resistance to sound energy and consequently dampens energy propagation. Because the round window niche is not adequately evaluated by otoscopy and may be incompletely exposed during an operation, otologic surgeons may not always correctly identify associated pathology. Thus, radiologists play an essential role in the identification and classification of diseases affecting the round window. The purpose of this review is to highlight the developmental, acquired, neoplastic, and iatrogenic range of pathologies that can be encountered in round window dysfunction.

Cochlear Implant

Cochlear implant is the first approved cranial nerve stimulator that works by directly stimulating the cochlear nerve. The medical and societal impact of this revolutionary device cannot be understated. This article reviews the evolving indications for cochlear implant, patient assessment, surgical approach, and outcomes for pediatric and adult cochlear implant that demonstrate its impact. Future concepts in cochlear implant are introduced briefly. This article covers a breadth of information; however, it is not intended be entirely comprehensive. Rather, it should serve as a foundation for understanding cochlear implant.

Human Otopathology of Cochlear Implant Drill-out Procedures

OBJECTIVE

Human otopathology following drill-out procedures for cochlear implantation (CI) in cases with labyrinthitis ossificans (LO) has not been previously described. This study uses the high sensitivity of histopathology to (1) evaluate surgical drill-out technique with associated intracochlear findings and (2) quantify spiral ganglion neuron populations in a series of patients with LO who underwent CI.

STUDY DESIGN

Retrospective otopathology study.

SETTING

Otopathology laboratory.

SUBJECTS AND METHODS

Temporal bone (TB) specimens from cases with evidence of preoperative intracochlear fibroossification that required a drill-out procedure for CI electrode array insertion were included. All cases were histopathologically evaluated and 3-dimensional reconstructions of the cochleae were performed to interpret drilling paths and electrode trajectories.

RESULTS

Five TB specimens were identified, of which 4 underwent drill-out of the basal turn of the cochlea and 1 underwent a radical cochlear drill-out. In multiple TBs, drilling was imprecise with resultant damage to essential structures. Two TBs showed injury to the modiolus, which was associated with substantially decreased or even absent neuronal populations within these areas. In addition, 2 cases with inadequate drill-out or extensive LO of the basal turn resulted in extracochlear placement of electrode arrays into the vestibule due to persistent obstruction within the basal turn.

CONCLUSION

Otopathology highlights the challenges of drill-out procedures in cases of LO. Imprecise drilling paths, due to distortion of normal cochlear anatomy, risk injury to the modiolus and adjacent neurons as well as extracochlear placement of electrode arrays, both of which may contribute to poorer hearing outcomes.

Etiology-Specific Mineralization Patterns in Patients with Labyrinthitis Ossificans

BACKGROUND AND PURPOSE

Our aim was to identify whether specific patterns of ossification in labyrinthitis ossificans are associated with the known risk factors. Labyrinthitis ossificans has been described as sequela of prior temporal bone trauma, prior infection, and other disorders including sickle cell disease. Specific patterns of mineralization in the membranous labyrinth associated with these risk factors has not been previously described.

MATERIALS AND METHODS

This was a retrospective study evaluating temporal bone CT scans at our institution from November 2005 to May 2018 in patients with labyrinthitis ossificans. Membranous labyrinthine structures evaluated for ossification included the following: basal, middle, and apical cochlear turns; lateral, posterior, and superior semicircular canals; and the vestibule for both ears in all patients. These structures were assigned a severity score, 0-4, based on degree of mineralization. Clinical records were reviewed for potential labyrinthitis ossificans risk factors. Basic descriptive statistics and a mixed model were used to correlate the degree and patterns of ossification with clinical history.

RESULTS

Forty-four patients (58 ears) with labyrinthitis ossificans were identified and evaluated. The most common risk factors were chronic otomastoiditis (n = 18), temporal bone surgery (n = 9), temporal bone trauma (n = 6), sickle cell disease (n = 5), and meningitis (n = 4). For all etiologies, the semicircular canals were most severely affected, and the vestibule was the least. In patients with prior temporal bone surgery, significantly greater mineralization was seen in the basal turn of the cochlea (P = .027), the vestibule (P = .001), and semicircular canals (P < .001-.008). No significant pattern was identified in patients with meningitis, sickle cell disease, or trauma.

CONCLUSIONS

Significant patterns of mineralization in labyrinthitis ossificans were observed in patients with prior temporal bone surgery. For all etiologies, the semicircular canals were most severely affected. No significant mineralization pattern was observed in patients with chronic otomastoiditis, meningitis, sickle cell disease, or prior temporal bone trauma.

Hearing disorders - findings on computed tomography and magnetic resonance imaging: pictorial essay

Hearing disorders are usually unilateral and are more common in women. They can be congenital or acquired, and hearing loss is categorized as sensorineural, conductive, or mixed. The onset of hearing loss can be progressive or sudden, and it is a common reason for seeking medical attention. In this context, computed tomography and magnetic resonance imaging have assumed critical roles in the search for an etiological diagnosis and in guiding the therapeutic approach. In this pictorial essay, we illustrate the common causes of hearing loss, discussing the possible differential diagnoses and highlighting the most relevant imaging findings.

Deterioration of Vestibular Cells in Labyrinthitis

OBJECTIVE

To quantitatively assess the effect of serous labyrinthitis, suppurative labyrinthitis, and labyrinthitis ossificans on vestibular hair cells, dark cells, and transitional cells.

METHODS

We examined human temporal bone specimens with serous labyrinthitis, suppurative labyrinthitis, and labyrinthitis ossificans, then compared them with age-matched control groups without labyrinthitis. We evaluated the density of type I and II vestibular hair cells, dark cells, and transitional cells in the peripheral sensorial organs.

RESULTS

The mean density of type I vestibular hair cells in the maculae of the saccule significantly differed between the serous labyrinthitis group and its control group. The loss of type I and II vestibular hair cells in all of the peripheral sensorial organs was significantly higher in the suppurative labyrinthitis group than in its control group. The mean density of dark cells in the lateral and posterior semicircular canals was significantly lower in the suppurative labyrinthitis group than in its control group. The mean density of type I and II vestibular hair cells, dark cells, and transitional cells was significantly lower in the labyrinthitis ossificans group than in its control group.

CONCLUSION

The loss of vestibular hair cells and degenerative changes in dark cells and transitional cells could affect vestibular function in patients with labyrinthitis.