Delayed hearing loss after cochlear implantation: Re-evaluating the role of hair cell degeneration

Delayed loss of residual acoustic hearing after cochlear implantation is a common but poorly understood phenomenon due to the scarcity of relevant temporal bone tissues. Prior histopathological analysis of one case of post-implantation hearing loss suggested there were no interaural differences in hair cell or neural degeneration to explain the profound loss of low-frequency hearing on the implanted side (Quesnel et al., 2016) and attributed the threshold elevation to neo-ossification and fibrosis around the implant. Here we re-evaluated the histopathology in this case, applying immunostaining and improved microscopic techniques for differentiating surviving hair cells from supporting cells. The new analysis revealed dramatic interaural differences, with a > 80 % loss of inner hair cells in the cochlear apex on the implanted side, which can account for the post-implantation loss of residual hearing. Apical degeneration of the stria further contributed to threshold elevation on the implanted side. In contrast, spiral ganglion cell survival was reduced in the region of the electrode on the implanted side, but apical counts in the two ears were similar to that seen in age-matched unimplanted control ears. Almost none of the surviving auditory neurons retained peripheral axons throughout the basal half of the cochlea. Relevance to cochlear implant performance is discussed.

Intracochlear Trauma and Local Ossification Patterns Differ Between Straight and Precurved Cochlear Implant Electrodes

HYPOTHESIS

Trauma to the osseous spiral lamina (OSL) or spiral ligament (SL) during cochlear implant (CI) insertion segregates with electrode type and induces localized intracochlear ossification and fibrosis.

BACKGROUND

The goal of atraumatic CI insertion is to preserve intracochlear structures, limit reactive intracochlear tissue formation, and preserve residual hearing. Previous qualitative studies hypothesized a localized effect of trauma on intracochlear tissue formation; however, quantitative studies failed to confirm this.

METHODS

Insertional trauma beyond the immediate insertion site was histologically assessed in 21 human temporal bones with a CI. Three-dimensional reconstructions were generated and virtually resectioned perpendicular to the cochlear spiral at high resolution. The cochlear volume occupied by ossification or fibrosis was determined at the midpoint of the trauma and compared with regions proximal and distal to this point.

RESULTS

Seven cases, all implanted with precurved electrodes, showed an OSL fracture beyond the immediate insertion site. Significantly more intracochlear ossification was observed at the midpoint of the OSL fracture, compared with the -26 to -18 degrees proximal and 28 to 56 degrees distal to the center. No such pattern was observed for fibrosis. In the 12 cases with a perforation of the SL (9 straight and 3 precurved electrodes), no localized pattern of ossification or fibrosis was observed around these perforations.

CONCLUSION

OSL fractures were observed exclusively with precurved electrodes in this study and may serve as a nidus for localized intracochlear ossification. Perforation of the SL, in contrast, predominantly occurred with straight electrodes and was not associated with localized ossification.

Human Histology after Structure Preservation Cochlear Implantation via Round Window Insertion

OBJECTIVES

Current surgical techniques aim to preserve intracochlear structures during cochlear implant (CI) insertion to maintain residual cochlear function. The optimal technique to minimize damage, however, is still under debate. The aim of this study is to histologically compare insertional trauma and intracochlear tissue formation in humans with a CI implanted via different insertion techniques.

METHODS

One recent temporal bone from a donor who underwent implantation of a full-length CI (576°) via round window (RW) insertion was compared with nine cases implanted via cochleostomy (CO) or extended round window (ERW) approach. Insertional trauma was assessed on H&E-stained histological sections. 3D reconstructions were generated and virtually re-sectioned to measure intracochlear volumes of fibrosis and neo-ossification.

RESULTS

The RW insertion case showed electrode translocation via the spiral ligament. 2/9 CO/ERW cases showed no insertional trauma. The total volume of the cochlea occupied by fibro-osseous tissue was 10.8% in the RW case compared with a mean of 30.6% (range 8.7%-44.8%, N = 9) in the CO/ERW cases. The difference in tissue formation in the basal 5 mm of scala tympani, however, was even more pronounced when the RW case (12.3%) was compared with the cases with a CO/ERW approach (mean of 93.8%, range 81% to 100%, N = 9).

CONCLUSIONS

Full-length CI insertions via the RW can be minimally traumatic at the cochlear base without inducing extensive fibro-osseous tissue formation locally. The current study further supports the hypothesis that drilling of the cochleostomy with damage to the endosteum incites a local tissue reaction.

LEVEL OF EVIDENCE

4: Case-control study Laryngoscope, 134:945-953, 2024.

Incomplete Partition Type II Cochlear Malformations: Delineating the Three-Dimensional Structure from Digitized Human Histopathological Specimens

HYPOTHESIS

There are clinically relevant differences in scalae anatomy and spiral ganglion neuron (SGN) quantity between incomplete partition type II (IP-II) and normal cochleae.

BACKGROUND

IP-II is a commonly implanted cochlear malformation. Detailed knowledge of intracochlear three-dimensional (3D) morphology may assist with cochlear implant (CI) electrode selection/design and enable optimization of audiologic programming based on SGN maps.

METHODS

IP-II (n = 11) human temporal bone histological specimens were identified from the National Institute on Deafness and Other Communication Disorders National Temporal Bone Registry and digitized. The cochlear duct, scalae, and surgically relevant anatomy were reconstructed in 3D. A machine learning algorithm was applied to map the location and number of SGNs.

RESULTS

3D scalae morphology of the basal turn was normal. Scala tympani (ST) remained isolated for 540 degrees before fusing with scala vestibuli. Mean ST volume reduced below 1 mm 2 after the first 340 degrees. Scala media was a distinct endolymphatic compartment throughout; mean ± standard deviation cochlear duct length was 28 ± 3 mm. SGNs were reduced compared with age-matched norms (mean, 48%; range, 5-90%). In some cases, SGNs failed to ascend Rosenthal's canal, remaining in an abnormal basalward modiolar location. Two forms of IP-II were seen: type A and type B. A majority (98-100%) of SGNs were located in the basal modiolus in type B IP-II, compared with 76 to 85% in type A.

CONCLUSION

Hallmark features of IP-II cochleae include the following: 1) fusion of the ST and scala vestibuli at a mean of 540 degrees, 2) highly variable and overall reduced SGN quantity compared with normative controls, and 3) abnormal SGN distribution with cell bodies failing to ascend Rosenthal's canal.

Cochlear Ossification After Vestibular Schwannoma Surgery: A Temporal Bone Study

OBJECTIVE

This study aims to investigate patterns of cochlear ossification (CO) in cadaveric temporal bones of patients who underwent vestibular schwannoma (VS) surgery via the translabyrinthine (TL), middle cranial fossa (MF), or retrosigmoid (RS) approaches.

STUDY DESIGN

Histopathologic analysis of cadaveric temporal bones.

SETTING

Multi-institutional national temporal bone repository.

METHODS

The National Institute of Deafness and Communication Disorders and House Temporal Bone Laboratory at the University of California, Los Angeles and the Massachusetts Eye and Ear Otopathology Laboratory were searched for cadaveric temporal bones with a history of VS for which microsurgery was performed. Exclusion criteria included non-VS and perioperative death within 30 days of surgery. Temporal bones were analyzed histologically for CO of the basal, middle, and apical turns.

RESULTS

Of 92 temporal bones with a history of schwannoma from both databases, 12 of these cases met the inclusion criteria. The approaches for tumor excision included 2 MF, 4 RS, and 6 TL approaches. CO was observed in all temporal bones that had undergone TL surgery. Among temporal bones that had undergone MF or RS surgeries, 5/6 had no CO, and 1/6 had partial ossification. This single case was noted to have intraoperative vestibular violation after RS surgery upon histopathologic and chart review.

CONCLUSION

In this temporal bone series, all temporal bones that had undergone TL demonstrated varying degrees of CO on histological analysis. MF and RS cases did not exhibit CO except in the case of vestibular violation. When cochlear implantation is planned or possible after VS surgery, surgeons may consider using a surgical approach that does not violate the labyrinth.

Three-dimensional quantification of fibrosis and ossification after cochlear implantation via virtual re-sectioning: Potential implications for residual hearing

Hearing preservation may be achieved initially in the majority of patients after cochlear implantation, however, a significant proportion of these patients experience delayed hearing loss months or years later. A prior histological report in a case of delayed hearing loss suggested a potential cochlear mechanical origin of this hearing loss due to tissue fibrosis, and older case series highlight the frequent findings of post-implantation fibrosis and neoosteogenesis though without a focus on the impact on residual hearing. Here we present the largest series (N = 20) of 3-dimensionally reconstructed cochleae based on digitally scanned histologic sections from patients who were implanted during their lifetime. All patients were implanted with multichannel electrodes via a cochleostomy or an extended round window insertion. A quantified analysis of intracochlear tissue formation was carried out via virtual re-sectioning orthogonal to the cochlear spiral. Intracochlear tissue formation was present in every case. On average 33% (SD 14%) of the total cochlear volume was occupied by new tissue formation, consisting of 26% (SD 12%) fibrous and 7% (SD 6%) bony tissue. The round window was completely covered by fibro-osseous tissue in 85% of cases and was associated with an obstruction of the cochlear aqueduct in 100%. The basal part of the basilar membrane was at least partially abutted by the electrode or new tissue formation in every case, while the apical region, corresponding with a characteristic frequency of < 500 Hz, appeared normal in 89%. This quantitative analysis shows that after cochlear implantation via extended round window or cochleostomy, intracochlear fibrosis and neoossification are present in all cases at anatomical locations that could impact normal inner ear mechanics.

Voluntary Field Recall of Advanced Bionics HiRes Cochlear Implants: A Single-Institution Experience

OBJECTIVES

In 2020, Advanced Bionics (AB) announced a recall of two cochlear implant (CI) models, the "HiRes Ultra" and "HiRes Ultra 3D", because of reports of hearing degradation. The present study examines clinical parameters and patient features in cases of device failure and evaluates outcomes after reimplantation.

MATERIALS AND METHODS

A series of 52 patients implanted with the recalled devices experienced suspected device failure and subsequently underwent revision CI placement at a tertiary academic medical center between December 2019 and November 2021.

RESULTS

Consonant-nucleus-consonant scores and individual phonemes increased significantly between patients' preoperative evaluation and primary cochlear implantation. Performance declined significantly before revision and recovered after revision CI placement. Similarly, pure-tone average thresholds improved between preoperative and primary CI, fell before revision surgery, and were corrected with revision implantation. As a group, patients reached their peak hearing performance significantly faster after revision CI (mean ± standard deviation, 53.4 ± 51.8 d) compared with their primary CI (mean ± standard deviation, 260.6 ± 245.9 d). Electrical field imaging performed by AB and device impedance measurements were found to be abnormal in the basally positioned electrodes (electrodes 9-16).

CONCLUSION

Hearing performance degradation is significant in AB Ultra device failures and seems to be linked to the basal-most electrodes in the array. Revision outcomes have been robust, necessitating continued monitoring of affected patients and support for reimplantation procedures.

LEVEL OF EVIDENCE

IV.

Development of an interdisciplinary microtia-atresia care model: A single-center 20-year experience

Objectives

Microtia and aural atresia are congenital ear anomalies with a wide-ranging spectrum of phenotypes and varied functional and psychosocial consequences for patients. This study seeks to analyze the management of microtia-atresia patients at our center over a 20-year period and to propose recommendations for advancing microtia-atresia care at a national level.

Methods

We performed a retrospective analysis of data from patients presenting to the Massachusetts Eye and Ear (Boston, MA) for initial otolaryngology consultation for congenital microtia and/or aural atresia between 1999 and 2018.

Results

Over the 20-year study period, 229 patients presented to our microtia-atresia center at a median age of 7 years. The severity of microtia was most commonly classified as grade III (n = 87, 38%), 61% (n = 140) of patients had complete atresia, the median Jahrsdoerfer grading scale score was 6 (range 0-10), and 81 patients (35%) underwent surgery for microtia repair. For hearing rehabilitation, 30 patients (64%) underwent bone conduction device implantation and 17 patients (36%) underwent atresiaplasty. The implementation of an interdisciplinary, longitudinal care model resulted in an increase in patient (r = 0.819, p < .001) and surgical volume (microtia surgeries, r = 0.521, p = .019; otologic surgeries, r = 0.767, p < .001) at our center over time.

Conclusion

An interdisciplinary team approach to microtia-atresia patient care may result in increased patient volume, which could improve aesthetic and hearing outcomes over time by concentrating care and surgical expertise. Future work should aim to establish standardized clinical consensus recommendations to guide the creation of high-quality microtia-atresia care programs.

Level of Evidence

4.

Otopathologic and Computed Tomography Correlation of Internal Auditory Canal Diverticula in Otosclerosis

INTRODUCTION

Internal auditory canal (IAC) diverticula, also known as IAC cavitary lesions or anterior cupping of the IAC, observed in otopathologic specimens and high-resolution computed tomography (CT) scans of the temporal bone are thought to be related to otosclerosis. Herein, we examined the usefulness of CT scans in identifying diverticula and determined whether IAC diverticula are associated with otosclerosis on otopathology.

METHODS

One hundred five consecutive specimens were identified from the National Temporal Bone Hearing and Balance Pathology Resource Registry. Inclusion criteria included the availability of histologic slides and postmortem specimen CT scans. Exclusion criteria included cases with severe postmortem changes or lesions causing bony destruction of the IAC.

RESULTS

Ninety-seven specimens met criteria for study. Of these, 42% of the specimens were from male patients, and the average age of death was 77 years (SD = 18 yr). IAC diverticula were found in 48 specimens, of which 46% were identified in the CT scans. The mean area of the IAC diverticula was 0.34 mm 2 . The sensitivity and specificity of detecting IAC diverticula based on CT were 77% and 63%, respectively. Overall, 27% of specimens had otosclerosis. Histologic IAC diverticula were more common in specimens with otosclerosis than those without (37.5% versus 16%; p = 0.019). Cases with otosclerosis had a greater mean histologic diverticula area compared with nonotosclerosis cases (0.69 mm 2 versus 0.14 mm 2 ; p = 0.001).

CONCLUSION

IAC diverticula are commonly found in otopathologic specimens with varied etiologies, but larger diverticula are more likely to be associated with otosclerosis. The sensitivity and specificity of CT scans to detect IAC diverticula are limited.

Cochlear implants: Causes, effects and mitigation strategies for the foreign body response and inflammation

Cochlear implants provide effective auditory rehabilitation for patients with severe to profound sensorineural hearing loss. Recent advances in cochlear implant technology and surgical approaches have enabled a greater number of patients to benefit from this technology, including those with significant residual low frequency acoustic hearing. Nearly all cochleae implanted with a cochlear implant electrode array develop an inflammatory and fibrotic response. This tissue reaction can have deleterious consequences for implant function, residual acoustic hearing, and the development of the next generation of cochlear prosthetics. This article reviews the current understanding of the inflammatory/foreign body response (FBR) after cochlear implant surgery, its impact on clinical outcome, and therapeutic strategies to mitigate this response. Findings from both in human subjects and animal models across a variety of species are highlighted. Electrode array design, surgical techniques, implant materials, and the degree and type of electrical stimulation are some critical factors that affect the FBR and inflammation. Modification of these factors and various anti-inflammatory pharmacological interventions have been shown to mitigate the inflammatory/FBR response. Ongoing and future approaches that seek to limit surgical trauma and curb the FBR to the implanted biomaterials of the electrode array are discussed. A better understanding of the anatomical, cellular and molecular basis of the inflammatory/FBR response after cochlear implantation has the potential to improve the outcome of current cochlear implants and also facilitate the development of the next generation of neural prostheses.

Assessment of Sudden Sensorineural Hearing Loss After COVID-19 Vaccination

IMPORTANCE

Emerging reports of sudden sensorineural hearing loss (SSNHL) after COVID-19 vaccination within the otolaryngological community and the public have raised concern about a possible association between COVID-19 vaccination and the development of SSNHL.

OBJECTIVE

To examine the potential association between COVID-19 vaccination and SSNHL.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study and case series involved an up-to-date population-based analysis of 555 incident reports of probable SSNHL in the Centers for Disease Control and Prevention Vaccine Adverse Events Reporting System (VAERS) over the first 7 months of the US vaccination campaign (December 14, 2020, through July 16, 2021). In addition, data from a multi-institutional retrospective case series of 21 patients who developed SSNHL after COVID-19 vaccination were analyzed. The study included all adults experiencing SSNHL within 3 weeks of COVID-19 vaccination who submitted reports to VAERS and consecutive adult patients presenting to 2 tertiary care centers and 1 community practice in the US who were diagnosed with SSNHL within 3 weeks of COVID-19 vaccination.

EXPOSURES

Receipt of a COVID-19 vaccine produced by any of the 3 vaccine manufacturers (Pfizer-BioNTech, Moderna, or Janssen/Johnson & Johnson) used in the US.

MAIN OUTCOMES AND MEASURES

Incidence of reports of SSNHL after COVID-19 vaccination recorded in VAERS and clinical characteristics of adult patients presenting with SSNHL after COVID-19 vaccination.

RESULTS

A total of 555 incident reports in VAERS (mean patient age, 54 years [range, 15-93 years]; 305 women [55.0%]; data on race and ethnicity not available in VAERS) met the definition of probable SSNHL (mean time to onset, 6 days [range, 0-21 days]) over the period investigated, representing an annualized incidence estimate of 0.6 to 28.0 cases of SSNHL per 100 000 people per year. The rate of incident reports of SSNHL was similar across all 3 vaccine manufacturers (0.16 cases per 100 000 doses for both Pfizer-BioNTech and Moderna vaccines, and 0.22 cases per 100 000 doses for Janssen/Johnson & Johnson vaccine). The case series included 21 patients (mean age, 61 years [range, 23-92 years]; 13 women [61.9%]) with SSNHL, with a mean time to onset of 6 days (range, 0-15 days). Patients were heterogeneous with respect to clinical and demographic characteristics. Preexisting autoimmune disease was present in 6 patients (28.6%). Of the 14 patients with posttreatment audiometric data, 8 (57.1%) experienced improvement after receiving treatment. One patient experienced SSNHL 14 days after receiving each dose of the Pfizer-BioNTech vaccine.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, findings from an updated analysis of VAERS data and a case series of patients who experienced SSNHL after COVID-19 vaccination did not suggest an association between COVID-19 vaccination and an increased incidence of hearing loss compared with the expected incidence in the general population.

Teaching Endoscopic Ear Surgery

Endoscopic ear surgery (EES) has become an integral part of otologic surgery. Training in EES involves learning fundamental techniques for endoscopic visualization, becoming proficient at one-handed dissection, mastering use of instruments designed for endoscopic ear surgery, and learning to optimize the operating room setup specifically for EES. Despite the steep learning curve, EES offers several advantages over the microscope for otologic procedures. With the rise in the demand for minimally invasive approaches, EES has a clear role in the future of otologic surgery. Identifying strategies to improve the training process of EES for the novice and experienced otolaryngologist is paramount.

The Pathology of the Vestibular System in CANVAS

OBJECTIVE

To describe the site of lesion responsible for the severe, bilateral, symmetrical, selective loss of vestibular function in Cerebellar Ataxia with Neuronopathy and Vestibular Areflexia Syndrome (CANVAS), an adult-onset recessively-inherited ataxia, characterized by progressive imbalance due to a combination of cerebellar, somatosensory, and selective vestibular impairment with normal hearing.

METHODS

Histologic examination of five temporal bones and the brainstems from four CANVAS patients and the brainstem only from one more, each diagnosed and followed from diagnosis to death by one of the clinician authors.

RESULTS

All five temporal bones showed severe loss of vestibular ganglion cells (cell counts 3-16% of normal), and atrophy of the vestibular nerves, whereas vestibular receptor hair cells and the vestibular nuclei were preserved. In contrast, auditory receptor hair cells, the auditory ganglia (cell counts 51-100% of normal), and the auditory nerves were relatively preserved. In addition, the cranial sensory ganglia (geniculate and trigeminal), present in two temporal bones, also showed severe degeneration.

CONCLUSIONS

In CANVAS there is a severe cranial sensory ganglionopathy neuronopathy (ganglionopathy) involving the vestibular, facial, and trigeminal ganglia but sparing the auditory ganglia. These observations, when coupled with the known spinal dorsal root ganglionopathy in CANVAS, indicate a shared pathogenesis of its somatosensory and cranial nerve manifestations. This is the first published account of both the otopathology and neuropathology of CANVAS, a disease that involves the central as well as the peripheral nervous system.

Histopathologic Evaluation of Intralabyrinthine Schwannoma

OBJECTIVES

The aim of this study is to perform a histopathologic analysis of temporal bones with an intralabyrinthine schwannoma (ILS) in order to characterize its extension.

METHODS

Archival temporal bones with a diagnosis of sporadic schwannoma were identified. Both symptomatic and occult nonoperated ILS were included for further analysis.

RESULTS

A total of 6 ILS were identified, with 4 intracochlear and 2 intravestibular schwannomas. All intracochlear schwannomas involved the osseous spiral lamina, with 2 extending into the modiolus. The intravestibular schwannomas were limited to the vestibule, but growth into the bone next to the crista of the lateral semicircular canal was observed in 1 patient.

CONCLUSIONS

Complete removal of an ILS may require partial removal of the modiolus or bone surrounding the crista ampullaris as an ILS may extend into these structures, risking damage of the neuronal structures. Due to the slow growth of the ILS, it remains unclear if a complete resection is required with the risk of destroying neural structures hindering hearing rehabilitation with a cochlear implant.

Topical fibroblast growth factor-2 for treatment of chronic tympanic membrane perforations

OBJECTIVE

To determine the efficacy of fibroblast growth factor-2 (FGF-2) in treating chronic nonhealing tympanic membrane (TM) perforations.

METHOD

Double-blinded, randomized placebo controlled phase 2 clinical trial for patients with chronic TM perforations of more than 3 months duration with a cross-over arm. Patients received either FGF-2 or placebo (sterile water) saturated gelatin sponge in the perforation after rimming the perforation under topical anesthesia. The perforation was then covered with Tisseel fibrin glue. The primary endpoint was complete closure of the TM perforation. Secondary end points included change in hearing and partial TM closure rates. The TM was examined every 3 weeks with otoendoscopy for closure. The treatment was repeated if there was incomplete closure every 3 weeks up to a total of three treatments per arm.

RESULTS

Seventy four patients were recruited for the study. Fifty seven met eligibility criteria and fifty four completed the study. Ten of 14 perforations closed completely in the placebo group (71.4%) and 23 of 40 perforations closed completely in the FGF-2 treatment group (57.5%), P value = .36. Pure tone averages and word recognition scores were not statistically significantly different between study groups post-treatment. After initial complete closure, re-perforation occurred in seven FGF-2 treated patients and two placebo patients making the effective final closure rate 40% for FGF and 57% for placebo, respectively.

CONCLUSION

No statistically significant difference in tympanic membrane perforation closure rate was found between the FGF-2 and placebo groups. There were no differences in hearing outcomes between the groups.

LEVEL OF EVIDENCE

1b.

Suction mitigation of airborne particulate generated during sinonasal drilling and cautery

Background

Coronavirus disease 2019 (COVID‐19) has significantly impacted endonasal surgery, and recent experimentation has demonstrated that sinonasal drilling and cautery have significant propensity for airborne particulate generation immediately adjacent to the surgical field. In the present investigation, we assessed nasopharyngeal suctioning as a mitigation strategy to decrease particulate spread during simulated endonasal surgical activity.

Methods

Airborne particulate generation in the 1‐µm to 10‐µm range was quantified with an optical particle sizer in real‐time during cadaveric‐simulated anterior and posterior endonasal drilling and cautery conditions. To test suction mitigation, experiments were performed both with and without a rigid suction placed in the contralateral nostril, terminating in the nasopharynx.

Results

Both anterior (medial maxillary wall and nasal septum) and posterior (sphenoid rostrum) drilling produced significant particulate generation in the 1‐µm to 10‐µm range throughout the duration of drilling (p < 0.001) without the use of suction, whereas nasopharyngeal suction use eliminated the detection of generated airborne particulate. A similar effect was seen with nasal cautery, with significant particle generation (p < 0.001) that was reduced to undetectable levels with the use of nasopharyngeal suction.

Conclusion

The use of nasopharyngeal suctioning via the contralateral nostril minimizes airborne particulate spread during simulated sinonasal drilling and cautery. In the era of COVID‐19, this technique offers an immediately available measure that may increase surgical safety.

Aerosol Dispersion During Mastoidectomy and Custom Mitigation Strategies for Otologic Surgery in the COVID-19 Era

Objective

To investigate small-particle aerosolization from mastoidectomy relevant to potential viral transmission and to test source-control mitigation strategies.

Study Design

Cadaveric simulation.

Setting

Surgical simulation laboratory.

Methods

An optical particle size spectrometer was used to quantify 1- to 10-µm aerosols 30 cm from mastoid cortex drilling. Two barrier drapes were evaluated: OtoTent1, a drape sheet affixed to the microscope; OtoTent2, a custom-structured drape that enclosed the surgical field with specialized ports.

Results

Mastoid drilling without a barrier drape, with or without an aerosol-scavenging second suction, generated large amounts of 1- to 10-µm particulate. Drilling under OtoTent1 generated a high density of particles when compared with baseline environmental levels (P < .001, U = 107). By contrast, when drilling was conducted under OtoTent2, mean particle density remained at baseline. Adding a second suction inside OtoTent1 or OtoTent2 kept particle density at baseline levels. Significant aerosols were released upon removal of OtoTent1 or OtoTent2 despite a 60-second pause before drape removal after drilling (P < .001, U = 0, n = 10, 12; P < .001, U = 2, n = 12, 12, respectively). However, particle density did not increase above baseline when a second suction and a pause before removal were both employed.

Conclusions

Mastoidectomy without a barrier, even when a second suction was added, generated substantial 1- to 10-µm aerosols. During drilling, large amounts of aerosols above baseline levels were detected with OtoTent1 but not OtoTent2. For both drapes, a second suction was an effective mitigation strategy during drilling. Last, the combination of a second suction and a pause before removal prevented aerosol escape during the removal of either drape.

Quantifying Aerosolization of Facial Plastic Surgery Procedures in the COVID-19 Era: Safety and Particle Generation in Craniomaxillofacial Trauma and Rhinoplasty

Background: COVID-19 poses a potentially significant infectious risk during procedures of the head and neck due to high viral loads in the nasal cavity and nasopharynx. Facial plastic surgery has significant exposure to these areas during craniomaxillofacial trauma procedures and rhinoplasty. Methods: Airborne particulate generation in the 1-10 μm range was quantified with an optical particle sizer in real time during cadaveric-simulated rhinoplasty and facial trauma conditions. Procedures tested included mandibular plate screw drilling, calvarial drilling, nasal bone osteotomy, nasal dorsal rasping, and piezoelectric saw use. Particulate generation was measured both adjacent to the surgical site and at surgeon mouth level (SML). Results: Mandibular plate screw drilling without irrigation generated significant particulate both adjacent to the surgical site and at SML (p < 0.01). Irrigation mitigated particulate generation at SML to nonsignificant levels. Calvarial drilling additionally produced substantial particulate above baseline adjacent to the surgical site (p < 0.01). Standard nasal osteotomies and dorsal rasping did not generate detectable airborne particulate, whereas piezoelectric saw use was associated with significant particulate generation both adjacent to the surgical site (p < 0.001) and at SML (p < 0.01). At SML, smaller particulate represented a significantly higher proportion of total particulate detected. Conclusions: The majority of craniomaxillofacial trauma procedures involve particle generation that may be limited in spread by the use of local irrigation. Most bony work involved in rhinoplasty can be safely performed without a high degree of particle formation. The use of piezoelectric instruments in rhinoplasty should be avoided when concerned for particulate generation.

Otopathology in CHARGE syndrome

Postmortem temporal bone computed tomography (CT) and histopathologic findings in an infant with CHARGE syndrome revealed bilateral cochleovestibular hypoplasia, including cochlear pathology relevant to cochlear implant candidacy. Both ears had absence of the superior semicircular canals (SCCs), severely hypoplastic posterior SCCs, and hypoplastic (right ear) or absent (left ear) lateral SCCs seen on CT and histopathology. Histopathology further revealed the absence of all SCC ampullae except the right lateral SCC ampulla and atrophic vestibular neuroepithelium in the saccule and utricle bilaterally. The right cochlea consisted of a basal turn with patent round window, and malformed middle turn (type IV cochlear hypoplasia), with a small internal auditory canal (IAC) but near normal cochlear nerve aperture (fossette). Quantification of spiral ganglion neurons (SGNs) on histologic sections revealed a reduced SGN population (35% of normal for age), but this ear would still have likely achieved benefit from a cochlear implant based on this population. The left cochlea consisted of only a basal turn with patent round window (type III cochlear hypoplasia) with a small IAC and very small cochlear nerve aperture. Notably, histology revealed that there were no SGNs in the cochlea, and therefore, this ear would not have been a good candidate for cochlear implantation.

Level of evidence: IV.

Temporal bone histopathology: Superior semicircular canal dehiscence

OBJECTIVES

To present a histopathological case of a 91-year-old woman who was diagnosed with superior semicircular canal dehiscence postmortem.

METHODS

The patient was a registered donor with the National Temporal Bone Donor Program at the NIDCD National Temporal Bone, Hearing and Balance Pathology Resource Registry. Computed tomography imaging was performed on each temporal bone. The temporal bones were decalcified with ethylenediaminetetracetate and embedded in celloidin, and tissue sections were stained with hematoxylin and eosin. Horizontal sections were taken through the left temporal bone, and vertical sections were taken through the right temporal bone.

RESULTS

Histopathological sections taken through the right temporal bone demonstrated no bone between the membranous wall of the superior semicircular canal and the middle fossa dura. There was no histopathological evidence of superior semicircular canal dehiscence in the left temporal bone; however, a small dehiscence would not be identified on horizontal sections. Microcavitations were observed in the common crus of the left temporal bone.

CONCLUSION

This reports describes the case of a woman who was diagnosed with superior semicircular canal dehiscence postmortem. The presence of microcavitations in the temporal bone is consistent with osteoclastic activity, which may play a role in the development of superior canal dehiscence.

Otopathology Findings in Otosclerosis With Lateral Semicircular Canal Fenestration

A study of clinical records and temporal bone histopathology from a woman with bilateral otosclerosis who was treated with lateral semicircular canal fenestration procedures as well as stapedectomy.

The Size of Internal Auditory Canal Diverticula Is Unrelated to Degree of Hearing Loss

OBJECTIVES

To explore the relationship between hearing loss and the internal auditory canal (IAC) diverticula. To determine whether diverticula exist within or medial to the otic capsule and the prevalence in a control population.

METHODS

Retrospective review of adult patients with radiologic evidence of an IAC diverticulum, no evidence of otosclerosis, and audiometric testing. Analyzed degree of hearing loss and width, length, height, and volume of diverticulum. Hounsfield unit (HU) measurements lateral and medial to the diverticulum.

RESULTS

Pure tone average (PTA), air-bone gap, and WRS (word recognition score) did not correlate with length, width, height, and volume of the diverticula. In patients with a unilateral diverticulum, there was no difference in mean PTA or WRS when comparing the diverticulum and nondiverticulum sides. Mean HU lateral to the diverticulum (2104 HU) was found to be significantly higher than medial to the diverticulum (1818 HU). There is a 5.6% prevalence of IAC diverticula in patients who underwent high-resolution computed tomography (CT) scans for chronic sinusitis (control group).

CONCLUSION

These data support the notion that hearing loss in this population is a product of sampling bias. The size of IAC diverticula does not correlate with the degree of hearing loss, and there is no statistically significant association between sensorineural hearing loss (SNHL) and the presence of an IAC diverticulum. IAC diverticula may exist medial to, rather than within, the otic capsule given the significant difference in mean HUs medial and lateral to the diverticula.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:1011-1015, 2020.

Otopathology in Angiosarcoma of the Temporal Bone

OBJECTIVES/HYPOTHESIS

Investigate the otopathology of angiosarcoma of the temporal bone, which has not been previously described in the literature.

STUDY DESIGN

Postmortem evaluation and literature review.

METHODS

Postmortem histological evaluation of the temporal bones and review of the literature for the treatment and prognosis of this rare disease were performed.

RESULTS

A 50-year-old male with right chronic otitis media presented with progressive hearing loss, disequilibrium, otalgia, and acute facial paresis. Biopsy of the external auditory canal was unrevealing, but specimens from a canal wall down tympanomastoidectomy later showed high-grade angiosarcoma. Magnetic resonance imaging demonstrated an unresectable middle ear and mastoid mass extending superiorly into the temporal lobe. The patient received induction chemotherapy followed by proton beam radiation therapy and concurrent paclitaxel and bevacizumab. His course was complicated by a cerebrospinal fluid leak and cauda equina syndrome from leptomeningeal sarcomatosis. The patient died after developing meningitis and a temporal lobe abscess. Postmortem otopathology revealed persistent angiosarcoma in the internal auditory canal, although none was found in the middle ear or mastoid. There was inflammatory infiltrate throughout the mastoid, with direct extension of neutrophils and bacteria into the cochlea and through the tegmen into the middle cranial fossa.

CONCLUSIONS

Angiosarcoma of the temporal bone can arise in the setting of chronic otitis media. In this case, postmortem temporal bone sections demonstrated viable cancer despite chemoradiation. Inflammatory infiltrates crossing from the middle ear/mastoid into the labyrinth and central nervous system illustrate pathways for the development of otogenic meningitis.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:737-742, 2019.

Third-generation bisphosphonates for cochlear otosclerosis stabilizes sensorineural hearing loss in long-term follow-up

Objective

To assess long‐term hearing outcomes in patients treated with third‐generation bisphosphonates for otosclerosis‐related progressive sensorineural hearing loss (SNHL).

Study Design

Retrospective case series review

Methods

We performed a retrospective case series review of patients with otosclerosis and progressive SNHL. Patients were treated with either risedronate or zoledronate after a diagnosis of otosclerosis with a significant SNHL component. Bone conduction pure tone threshold averages (BC‐PTAs) and word recognition scores (WRS) before and after bisphosphonate administration in long‐term follow‐up was analyzed. Significant change in BC‐PTA was defined as greater than 10dB or between 4% and 18% in WRS based on binomial variance.

Results

Seven patients were identified and 14 ears met inclusion criteria. Three patients were female and the mean age was 48.3 ± 10.3 years. The mean duration between treatment with bisphosphonate administration and long‐term post‐treatment follow‐up audiometry was 87.6 ± 18.3 months, with a range of 61.6 to 109.1 months and median of 89.2 months. Analysis using BC‐PTA and WRS demonstrated that 11 ears remained stable while 2 improved and 1 worsened. No patient experienced any major complication as the result of bisphosphonate therapy.

Conclusion

Treatment with third‐generation bisphosphonates is associated with stability in otosclerosis‐related sensorineural hearing over 5‐ to 9‐year period. These results suggest that such medications may prevent the progression of SNHL in patients with otosclerosis.

Level of Evidence

4 (Case series).

Measurement for Detection of Incomplete Partition Type II Anomalies on MR Imaging

BACKGROUND AND PURPOSE

Incomplete partition type II of the cochlea, commonly coexisting with an enlarged vestibular aqueduct, can be a challenging diagnosis on MR imaging due to the presence of a dysplastic spiral lamina-basilar membrane neural complex, which can resemble the normal interscalar septum. The purpose of this study was to determine a reproducible, quantitative cochlear measurement to assess incomplete partition type II anomalies in patients with enlarged vestibular aqueducts using normal-hearing ears as a control population.

MATERIALS AND METHODS

Retrospective analysis of 27 patients with enlarged vestibular aqueducts (54 ears) and 28 patients (33 ears) with normal audiographic findings who underwent MR imaging was performed. Using reformatted images from a cisternographic 3D MR imaging produced in a plane parallel to the lateral semicircular canal, we measured the distance (distance X) between the osseous spiral lamina-basilar membrane complex of the upper basal turn and the first linear signal void anterior to the basilar membrane.

RESULTS

The means of distance X in patients with normal hearing and prospectively diagnosed incomplete partition type II were, respectively, 0.93 ± 0.075 mm (range, 0.8-1.1 mm) and 1.55 ± 0.25 mm (range, 1-2.1 mm; P < .001). Using 3 SDs above the mean of patients with normal hearing (1.2 mm) as a cutoff for normal, we diagnosed 21/27 patients as having abnormal cochleas; 4/21 were diagnosed retrospectively. This finding indicated that almost 20% of patients were underdiagnosed. Interobserver agreement with 1.2 mm as a cutoff between normal and abnormal produced a κ score of 0.715 (good).

CONCLUSIONS

Incomplete partition type II anomalies on MR imaging can be subtle. A reproducible distance X of ≥1.2 mm is considered abnormal and may help to prospectively diagnose incomplete partition type II anomalies.

The pattern and degree of capsular fibrous sheaths surrounding cochlear electrode arrays

An inflammatory tissue reaction around the electrode array of a cochlear implant (CI) is common, in particular at the electrode insertion region (cochleostomy) where mechanical trauma often occurs. However, the factors determining the amount and causes of fibrous reaction surrounding the stimulating electrode, especially medially near the perimodiolar location, are unclear. Temporal bone (TB) specimens from patients who had undergone cochlear implantation during life with either Advanced Bionics (AB) Clarion ™ or HiRes90K™ (Sylmar, CA, USA) devices that have a half-band and a pre-curved electrode, or Cochlear ™ Nucleus (Sydney, Australia) device that have a full-band and a straight electrode were evaluated. The thickness of the fibrous tissue surrounding the electrode array of both types of CI devices at both the lower (LB) and upper (UB) basal turns of the cochlea was quantified at three locations: the medial, inferior, and superior aspects of the sheath. Fracture of the osseous spiral lamina and/or marked displacement of the basilar membrane were interpreted as evidence of intracochlear trauma. In addition, post-operative word recognition scores, duration of implantation, and post-operative programming data were evaluated. Seven TBs from six patients implanted with AB devices and five TBs from five patients implanted with Nucleus devices were included. A fibrous capsule around the stimulating electrode array was present in all twelve specimens. TBs implanted with AB device had a significantly thicker fibrous capsule at the medial aspect than at the inferior or superior aspects at both locations (LB and UB) of the cochlea (Wilcoxon signed-ranks test, p < 0.01). TBs implanted with a Nucleus device had no difference in the thickness of the fibrous capsule surrounding the track of the electrode array (Wilcoxon signed-ranks test, p > 0.05). Nine of fourteen (64%) basal turns of the cochlea (LB and UB of seven TBs) implanted with AB devices demonstrated intracochlear trauma compared to two of ten (20%) basal turns of the cochlea (LB and UB of five TBs) with Nucleus devices, (Fisher exact test, p < 0.05). There was no significant correlation between the thickness of the fibrous tissue and the duration of implantation or the word recognition scores (Spearman rho, p = 0.06, p = 0.4 respectively). Our outcomes demonstrated the development of a robust fibrous tissue sheath medially closest to the site of electric stimulation in cases implanted with the AB device electrode, but not in cases implanted with the Nucleus device. The cause of the asymmetric fibrous sheath may be multifactorial including insertional trauma, a foreign body response, and/or asymmetric current flow.

Post Hybrid Cochlear Implant Hearing Loss and Endolymphatic Hydrops

OBJECTIVE

To evaluate for potential causes of delayed loss of residual hearing that variably occurs with hybrid cochlear implants.

STUDY DESIGN

Histopathological evaluation of 29 human temporal bone (HTB) with cochlear implant (CI).

SETTING

The Neurotology and House HTB Laboratory of UCLA (House-UCLA).

SUBJECTS AND METHODS

HTB from CI patients from the House-UCLA HTB Laboratory (n = 28) and one courtesy of Massachusetts Eye and Ear Infirmary (MEEI). Histopathological analysis to identify the location of cochleostomy, fibrosis, and bone formation in the scala vestibuli and tympani, and endolymphatic hydrops. Spiral ganglion neuron counts were obtained. Statistical analysis compared presence of cochleostomy and location with the histopathological findings.

RESULTS

Seventeen of 29 bones with fibrosis in the scala vestibule (SV) and tympani had evidence of a cochleostomy involving the SV containing the ductus reunions, all of which had hydrops. Ten of 11 bones had no SV fibrosis, and a cochleostomy limited to the scala tympani, of which all had no hydrops. One HTB had moderate SV fibrosis not involving the ductus reuniens, and was without hydrops. One HTB had a SV cochleostomy but the electrode ruptured Reissner's membrane, and was without hydrops. Cochleostomy was significantly associated with SV fibrosis and hydrops (p < 0.01), those without hydrops had no SV atrophy (p < 0.01). Round window insertion was associated with no fibrosis and no hydrops.

CONCLUSION

We hypothesize that cochleostomies involving scala vestibuli incite fibrosis, compromising the ductus reuniens, causing hydrops which may cause the delayed loss of residual low frequency hearing in CI.

Delayed loss of hearing after hearing preservation cochlear implantation: Human temporal bone pathology and implications for etiology

After initially successful preservation of residual hearing with cochlear implantation, some patients experience subsequent delayed hearing loss. The etiology of such delayed hearing loss is unknown. Human temporal bone pathology is critically important in investigating the etiology, and directing future efforts to maximize long term hearing preservation in cochlear implant patients. Here we present the temporal bone pathology from a patient implanted during life with an Iowa/Nucleus Hybrid S8 implant, with initially preserved residual hearing and subsequent hearing loss. Both temporal bones were removed for histologic processing and evaluated. Complete clinical and audiologic records were available. He had bilateral symmetric high frequency severe to profound hearing loss prior to implantation. Since he was implanted unilaterally, the unimplanted ear was presumed to be representative of the pre-implantation pathology related to his hearing loss. The implanted and contralateral unimplanted temporal bones both showed complete degeneration of inner hair cells and outer hair cells in the basal half of the cochleae, and only mild patchy loss of inner hair cells and outer hair cells in the apical half. The total spiral ganglion neuron counts were similar in both ears: 15,138 (56% of normal for age) in the unimplanted right ear and 13,722 (51% of normal for age) in the implanted left ear. In the basal turn of the implanted left cochlea, loose fibrous tissue and new bone formation filled the scala tympani, and part of the scala vestibuli. Delayed loss of initially preserved hearing after cochlear implantation was not explained by additional post-implantation degeneration of hair cells or spiral ganglion neurons in this patient. Decreased compliance at the round window and increased damping in the scala tympani due to intracochlear fibrosis and new bone formation might explain part of the post-implantation hearing loss. Reduction of the inflammatory and immune response to cochlear implantation may lead to better long term hearing preservation post-implantation.

Minimally invasive endoscopic management of subglottic stenosis in children: success and failure

OBJECTIVE

To assess the efficacy and safety of endoscopic management of subglottic stenosis both as a primary and as an adjunctive treatment in the pediatric population.

METHODS

Retrospective review of pediatric patients with subglottic stenosis undergoing endoscopic airway procedures at a tertiary care pediatric medical center. Outcomes were assessed by systematic review to determine the success and failure of the endoscopic approach.

RESULTS

Forty patients (22 male, 18 female) underwent endoscopic interventions for a diagnosis of subglottic airway stenosis between 2003 and 2006. Age ranged from 22 days old to 20 years old. Recorded degree of subglottic stenosis ranged from 10% to 99%. Fifty-three percent (21/40) had a history of prematurity, and 40% (16/40) had secondary airway diagnoses. Twenty-four patients underwent an endoscopic intervention initially (including laser or dilation, with or without topical mitomycin treatment), including four patients who underwent tracheostomy prior to the first endoscopic intervention. Sixteen underwent laryngotracheoplasty initially, including ten patients who underwent tracheostomy prior to the laryngotracheoplasty. Endoscopic treatment resulted in resolution of symptoms, and/or decannulation, and no further need for an open procedure in 58% of patients. Of the 24 patients undergoing endoscopic interventions initially, 14 patients underwent two or more endoscopic interventions, and 10 patients subsequently required tracheostomy or laryngotracheoplasty. When endoscopic procedures were used as an adjunct to laryngotracheoplasty, 60% (12/20) had resolution of symptoms, underwent decannulation, and did not require tracheostomy or revision laryngotracheoplasty.

CONCLUSIONS

The endoscopic approach can be successful in the management of properly selected patients with subglottic stenosis, either as the initial treatment modality or as an adjunctive treatment in cases of re-stenosis after open airway surgery. The likelihood of success with a minimally invasive procedure as the primary treatment decreases with worsening initial grade of subglottic stenosis.

When the bell tolls on Bell's palsy: finding occult malignancy in acute-onset facial paralysis

PURPOSE

This study reports 4 cases of occult parotid malignancy presenting with sudden-onset facial paralysis to demonstrate that failure to regain tone 6 months after onset distinguishes these patients from Bell's palsy patients with delayed recovery and to propose a diagnostic algorithm for this subset of patients.

MATERIALS AND METHODS

A case series of 4 patients with occult parotid malignancies presenting with acute-onset unilateral facial paralysis is reported.

RESULTS

Initial imaging on all 4 patients did not demonstrate a parotid mass. Diagnostic delays ranged from 7 to 36 months from time of onset of facial paralysis to time of diagnosis of parotid malignancy. Additional physical examination findings, especially failure to regain tone, as well as properly protocolled radiologic studies reviewed with dedicated head and neck radiologists, were helpful in arriving at the diagnosis.

CONCLUSION

An algorithm to minimize diagnostic delays in this subset of acute facial paralysis patients is presented. Careful attention to facial tone, in addition to movement, is important in the diagnostic evaluation of acute-onset facial paralysis.

Investigating Murray's law in the chick embryo

According to the optimization principle known as Murray's law, the blood vessel geometry at a bifurcation satisfies the relation alpha = (D3(1) + D3(2))/D3(0) = 1, where D0, D1, and D2 are the diameters of the parent and two daughter vessels, respectively. Previous investigations have shown that mature blood vessels adhere to this law fairly closely. The purpose of this study was to test Murray's law in the developing extraembryonic blood vessels of 2-4 day-old chick embryos. Vessel diameters were measured manually using image analysis software. The measurements for the group of all vessels at all studied stages (n = 449) gave alpha = 1.01+/-0.34 (mean +/- SD), and the value of alpha is similar at all stages. These results indicate that Murray's law holds in the chick embryo, even before medial smooth muscle becomes functional, suggesting that blood vessels follow the same basic morphogenetic rules throughout life.