Temporal Bone Specimens Research Articles

Face and content validation of additive manufacturing temporal bone specimens.

Face and content validation of additive manufacturing temporal bone specimens.

Impact of cochlear detailed morphology on insertion results and intracochlear trauma of a slim pre-curved electrode array: a micro-CT study.

This study aimed to evaluate the impact of detailed cochlear dimensions, assessed using micro-CT (µCT) imaging, on insertion outcomes and associated trauma with a new slim, precurved electrode array. Eleven temporal bone specimens underwent implantation of a 22-electrode slim precurved array via the round window. High-resolution µCT scans post-implantation enabled visualization of cochlear structures and electrode positioning. Combination with subsequent scans taken after electrodes removal, we analyzed angular insertion depth (AID), insertion length, number of electrodes inserted, cochlear dimensions (specifically cochlear duct length (CDL), basal turn diameter, scala tympani dimension), and intracochlear trauma of fine structures. Statistical analyses were performed to correlate cochlear detailed dimensions and morphology with insertion outcomes and trauma. The mean AID was 351.82°, and the mean insertion length was 21.07mm. CDL showed positive correlations with AID and insertion length. Basal turn diameter (value B) positively correlated with AID and insertion length, unlike value A. Middle-basal turn (M/B) relationships (angle and height) significantly influenced insertion depth. The cochleae with smaller M/B heights and specific angles were more susceptible to insertion trauma. Larger basal turn diameters correlated with increased trauma and electrode translocation into the scala vestibuli. This study highlights the importance of precise cochlear measurements in predicting and optimizing cochlear implant outcomes. Specific cochlear dimensions and anatomical shapes were identified as critical factors affecting insertion depth, trauma risk, and electrode positioning. Utilizing micro-CT provided detailed insights into cochlear anatomy and insertion outcomes, offering valuable data for advancing cochlear implant technology and surgical practices.

Development and Evaluation of a Reusable, Force Measuring Tool for the Robot-Assisted Insertion of Cochlear Implant Electrode Arrays.

Limitations in human kinematics during cochlear implantation induce pressure transients and increased forces on intracochlear structures. Herein, we present a novel head-mounted surgical tool designed for the motorized insertion of cochlear implant electrode arrays. The tool integrates a force measurement feature to overcome the lack of haptic feedback in current robotic solutions. Utilizing a prototype device, we compare force measurements with those exerted on intracochlear structures in a realistic temporal bone model. Furthermore, we test the tool on six temporal bone specimens in a surgical setting to assess its performance in various anatomies. Force measurements exhibit good agreement with intracochlear forces, offering significantly improved resolution over manual, tactile sensing. Successful electrode array insertions in six cadaver specimens affirmed the feasibility of tool setup, motorized insertion and tool removal in different anatomies. The tool allows the robot-assisted insertion of cochlear implant electrode arrays and offers valuable insights during the surgical procedure, demonstrating promise for application in clinical contexts. This instrument has the potential to aid surgeons in achieving atraumatic placement of electrodes, consequently contributing to the improvement of hearing outcomes in cochlear implantation.

Relationship Between Cochlear Lateral Wall Changes and Endolymphatic Hydrops in Otitis Media.

Despite otitis media and various disease processes being associated with endolymphatic hydrops (EH), an exact explanation of the pathophysiology has yet to be reported. This study aimed to investigate the changes in the cochlear lateral wall structures and their potential correlation with the presence and severity of cochlear EH in acute and chronic otitis media cases. The investigations were conducted in both chinchilla animal model and human temporal bone specimens. We studied a total of 15 chinchilla and 25 human temporal bones from our collection, which were categorized into acute otitis media, chronic otitis media (COM), and control groups. Through quantitative analysis, we measured the area of cochlear lateral wall structures and observed the presence and the degree of EH using light microscopy. No significant changes were determined in the area of the spiral ligament (p > 0.05) across the species. However, a significant (p < 0.05) decrease in the mean area of the stria vascularis in the basal turn was identified in COM groups compared to controls of both species. Chinchilla model additionally exhibited pathology extending to the lower mid turn. A negative correlation was found between the mean strial area and the severity of EH in both the animal model and human samples. COM associated with significant changes in the stria vascularis that may lead to significant increase in the degree of EH. The presented animal model exhibited parallel findings with human samples, suggesting its viability as a valuable model for future studies. N/A Laryngoscope, 2024.

Development of an Algorithm for Correct Placement of the Basal Electrode Contact in the Context of Anatomy-Based Cochlear Implantation: A Proof of Concept

Plain Language SummaryTonotopic-matched stimulation of the cochlea is important in the context of anatomy-based cochlear implantation. The basal cochlear implant electrode contact is often placed in a frequency range higher than 10 kHz – when a normal insertion depth is reached – and can therefore be difficult to fit since current audio processors only stimulate for frequencies up to 8.5 kHz. This leads to a mismatch of high frequencies. This study represents a proof of concept for a tonotopic correct insertion and aims to develop an algorithm for a placement of the basal electrode below 8.5 kHz in an experimental setting. Therefore, pre- and postoperative CT scans were performed on 10 human temporal bone specimens. Tonotopic information about the aimed position of basal electrode contact was extracted from the imaging dataset by using 3D-curved multiplanar reconstruction and a newly developed mathematical approach. A specially designed cochlear implant electrode array was inserted in all specimens based on the individually calculated insertion depths. Positioning of the basal electrode contact was reached with only a small mean deviation of 37 ± 399 Hz and 0.06 ± 0.37 mm from the planned frequency of 8.25 kHz. In addition, the inserted electrode array adequately covered the apical regions of the cochleae. Using this algorithm, it was possible to position the basal electrode array contact in an area of the cochlea that can be correctly stimulated by the existing speech processors in the context of tonotopic correct fitting.

Numerical Simulations of the Epley Maneuver With Clinical Implications.

Canalith repositioning procedures to treat benign paroxysmal positional vertigo are often applied following standardized criteria, without considering the possible anatomical singularities of the membranous labyrinth for each individual. As a result, certain patients may become refractory to the treatment due to significant deviations from the ideal membranous labyrinth, that was considered when the maneuvers were designed. This study aims to understand the dynamics of the endolymphatic fluid and otoconia, within the membranous labyrinth geometry, which may contribute to the ineffectiveness of the Epley maneuver. Simultaneously, the study seeks to explore methods to avoid or reduce treatment failure. We conducted a study on the Epley maneuver using numerical simulations based on a three-dimensional medical image reconstruction of the human left membranous labyrinth. A high-quality micro-computed tomography of a human temporal bone specimen was utilized for the image reconstruction, and a mathematical model for the endolymphatic fluid was developed and coupled with a spherical particle model representing otoconia inside the fluid. This allowed us to measure the position and time of each particle throughout all the steps of the maneuver, using equations that describe the physics behind benign paroxysmal positional vertigo. Numerical simulations of the standard Epley maneuver applied to this membranous labyrinth model yielded unsatisfactory results, as otoconia do not reach the frontside of the utricle, which in this study is used as the measure of success. The resting times between subsequent steps indicated that longer intervals are required for smaller otoconia. Using different angles of rotation can prevent otoconia from entering the superior semicircular canal or the posterior ampulla. Steps 3, 4, and 5 exhibited a heightened susceptibility to failure, as otoconia could be accidentally displaced into these regions. We demonstrate that modifying the Epley maneuver based on the numerical results obtained in the membranous labyrinth of the human specimen under study can have a significant effect on the success or failure of the treatment. The use of numerical simulations appears to be a useful tool for future canalith repositioning procedures that aim to personalize the treatment by modifying the rotation planes currently defined as the standard criteria.

Effect of Matrix Size and Acquisition Mode on Image Quality and Radiation Dose of Ultra-High-Resolution CT of the Temporal Bone: An Anatomical Study.

Purpose: To compare image quality and radiation exposure between super- and ultra-high-resolution helical and super-high-resolution volumetric CT of the temporal bone. Methods: Six cadaveric temporal bone specimens were used to evaluate key temporal bone structures using the following CT reconstruction and acquisition modes: helical and single-volume acquisition modes in super-high resolution (0.25-mm slice thickness, 10242 matrix), and helical mode in ultra-high resolution (0.25-mm slice thickness, 20482 matrix). Two observers performed 5 previously described preoperative measurements, measured noise and signal-to-noise ratios for air, and noise for bone, and rated the visualization of 5 anatomical structures on a 4-point scale, for each reconstruction mode. Radiation dose exposure was recorded for each examination. Results: There was no significant difference between any of the quantitative or qualitative measurements in any of the reconstruction and acquisition modes. There was a slight increase in noise and a decrease in signal-to-noise ratio in the air using the single-volume mode (115 ± 13.1 HU and 8.37 ± 0.91, respectively) compared to the helicoidal super-high-resolution (92.4 ± 11.8 HU and 10.8 ± 1.26, respectively) and helicoidal ultra-high-resolution (91.1 ± 10.7 HU and 10.9 ± 1.39, respectively) modes (P < .002). The volumic CT dose index was 50.9 mGy with helical acquisition and 29.8 mGy with single-volume acquisition mode (P < .0001). Conclusion: The single-volume super-high-resolution acquisition mode allows a reduction in radiation dose exposure without compromising image quality compared to helical scanning, but with a slightly lower signal-to-noise ratio in air with the single-volume mode, while there was no difference in image quality between the helical super- and ultra-high-resolution modes.

Changes in hearing function and intracochlear morphology after electrode array insertion in minipigs

Background In temporal bone specimens from long-term cochlear implant users, foreign body response within the cochlea has been demonstrated. However, how hearing changes after implantation and fibrosis progresses within the cochlea is unknown. Objectives To investigate the short-term dynamic changes in hearing and cochlear histopathology in minipigs after electrode array insertion. Material and Methods Twelve minipigs were selected for electrode array insertion (EAI) and the Control. Hearing tests were performed preoperatively and on 0, 7, 14, and 28 day(s) postoperatively, and cochlear histopathology was performed after the hearing tests on 7, 14, and 28 days after surgery. Results Electrode array insertion had a significant effect for the frequency range tested (1 kHz–20kHz). Exudation was evident one week after electrode array insertion; at four weeks postoperatively, a fibrous sheath formed around the electrode. At each time point, the endolymphatic hydrops was found; no significant changes in the morphology and packing density of the spiral ganglion neurons were observed. Conclusions and Significance The effect of electrode array insertion on hearing and intracochlear fibrosis was significant. The process of fibrosis and endolymphatic hydrops seemed to not correlate with the degree of hearing loss, nor did it affect spiral ganglion neuron integrity in the 4-week postoperative period.

Quantitative analysis of 3D-printed custom ossicular prostheses motion using laser Doppler vibrometry.

&lt;b&gt;&lt;br&gt;Introduction:&lt;/b&gt; In chronic otitis media, the reconstruction of the middle ear&apos;s sound conducting system involves repairing the tympanic membrane and filling the space between ossicular chain remnants. The final shape of the prosthesis is usually determined intraoperatively. However, the ossicular chain may be preoperatively measured using computed tomography (CT) scans, and an individualized prosthesis can be designed. Custom 3D printing seems to be an attractive solution for optimal adjustment.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Aim:&lt;/b&gt; Our study aimed to assess the 3D-printed custom prosthesis movability and compare it to the original ossicular chain.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Material and methods:&lt;/b&gt; Five fresh-frozen temporal bone specimens were used. Using Cone-Beam CT scans, the incus model was designed individually and 3D-printed. The ossicular chain was reconstructed inside the cadaveric temporal bone. Acoustic stimuli were applied to the external ear canal one frequency at a time. The laser Doppler vibrometer (LDV) measured the intact and 3D-printed prosthesis reconstructed ossicular chain vibrations.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Results:&lt;/b&gt; At all stimulation frequencies, there was no significant difference in velocity values between the intact and reconstructed ossicular chain at the intensity of 80 dB SPL. The obtained values of the velocity gain were: -7.9 (SD-19) dB, -6.8 (SD8.12) dB, -10,9 (SD-5.3) dB, -7.4 (SD-8.16) dB for 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, respectively. The vibration threshold shift values ranged between -0.57 dB at 500 Hz and 3.81 dB at 2000 Hz.&lt;/br&gt; &lt;b&gt;&lt;br&gt;Conclusions:&lt;/b&gt; This study analyzed the movability of individualized 3D-printed custom ossicular prostheses using LDV. Compared to the intact ossicular chain, the reconstructed ossicular chain movability was characterized by statistically insignificant reduced movability at all tested frequencies. Because the prosthesis&apos;s new design conception as custom 3D individualized printing allows for patient-specific ossiculoplasty, it represents a promising new direction for ossicular chain reconstruction. It seems to be an attractive solution for prosthesis optimal adjustment and, hopefully, better hearing results.&lt;/br&gt.

Dynamic Molecular Markers of Otosclerosis in the Human Cochlea.

To investigate the role and distribution of various molecular markers using immunohistochemistry and immunofluorescence to further elucidate and understand the pathogenesis of otosclerosis. Archival celloidin formalin-fixed 20-micron thick histologic sections from 7 patients diagnosed with otosclerosis were studied and compared to controls. Sections in the mid-modiolar region were immunoreacted with rabbit polyclonal antibodies against nidogen-1, β2-laminin, collagen-IX, BSP, and monoclonal antibodies against TGF β-1 and ubiquitin. Digital images were acquired using a high-resolution light and laser confocal microscope. Nidogen-1, BSP, and collagen-IX were expressed in the otospongiotic regions, and to lesser extent, in the otosclerotic regions, the latter previously believed to be inactive. β2-laminin and ubiquitin were uniformly expressed in both otospongiotic and otosclerotic regions. There was a basal level of expression of all of these markers in the normal hearing and sensorineural hearing loss specimens utilized as control. TGF β -1, however, though present in the otosclerosis bones, was absent in the normal hearing and sensorineural hearing loss controls. Our results propose that the activity and function of TGF-1 may play a key role in the development and pathogenesis of otosclerosis. Further studies utilizing a higher number of temporal bone specimens will be helpful for future analysis and to help decipher its role as a potential target in therapeutic interventions.

Pull-Out Strength of Orthodontic Miniscrews in the Temporal Bone.

Minimally invasive cochlear implant surgery by using a microstereotactic frame demands solid connection to the bone. We aimed to determine the stability of commercially available orthodontic miniscrews to evaluate their feasibility for frame's fixation. In addition, which substitute material most closely resembles the mechanical properties of the human temporal bone was evaluated. Pull-out tests were carried out with five different types of orthodontic miniscrews in human temporal bone specimens. Furthermore, short fiber filled epoxy (SFFE), solid rigid polyurethane (SRPU50), bovine femur, and porcine iliac bone were evaluated as substitute materials. In total, 57 tests in human specimens and 180 tests in the substitute materials were performed. In human temporal bone, average pull-out forces ranged from 220 N to 285 N between screws. Joint stiffness in human temporal bone ranged between 14 N/mm and 358 N/mm. Statistically significant differences between the tested screws were measured in terms of stiffness and elastic energy. One screw type failed insertion due to tip breakage. No significant differences occurred between screws in maximum pull-out force. The average pull-out values of SFFE were 14.1 N higher compared to human specimen. Orthodontic miniscrews provided rigid fixation when partially inserted in human temporal bone, as evidenced by pull-out forces and joint stiffness. Average values exceeded requirements despite variations between screws. Differences in stiffness and elastic energy indicate screw-specific interface mechanics. With proper insertion, orthodontic miniscrews appear suitable for microstereotactic frame anchoring during minimally invasive cochlear implant surgery. However, testing under more complex loading is needed to better predict clinical performance. For further pull-out tests, the most suitable substitute material is SFFE.

Temporal bone histopathology in revision cochlear implantation

An increasing number of young infants, as early as six months of age with congenital hearing loss receive cochlear implantation, and it is probable that many of these patients will require revision surgery later in life. The possibility of explantation of the cochlear electrode and reimplantation may cause damage to the cochlea, compromising the speech perception outcome in revision implant is of concern. There is only one prior temporal bone histopathology study to look at the outcome of revision surgery and no prior study evaluating revision cochlear implantation that used the round window approach. We conducted a histopathological study of four temporal bone specimens from four patients who underwent revision cochlear implantation and when available post-operative speech perception tests were evaluated. In all cases, the reimplanted electrode followed into the same fibrous sheath without evidence of additional intracochlear damage due to revision surgery. The intracochlear damage from the initial cochlear implantation appears to be a more important factor in outcomes rather than changes associated with explantation and reimplantation.

Computed tomographic 3D analysis of the cochlear aqueduct—potential and limitations of clinical imaging

Background: The cochlear aqueduct (CA), which connects the scala tympani and the subarachnoid space, and its accompanying structures appear to have a significant relevance during cochlear implantation and an accurate visualization in clinical imaging is of great interest. Aims and Objective: This study aims to determine which potential and limitations clinically available imaging modalities have in the visualization of the CA. Methods: Micro-CT, flat-panel volume computed tomography with and without secondary reconstruction (fpVCT, fpVCTseco) and multislice computed tomography (MSCT) of 10 temporal bone specimen were used for 3D analysis of the CA. Results: FpVCTseco proved superior in visualizing the associated structures and lateral portions of the CA, which merge into the basal turn of the cochlea. All clinical imaging modalities proved equal in analyzing the length, total volume of the CA and its area of the medial orifice. Conclusion: The choice of the most accurate clinical imaging modality to evaluate the CA and its associated structures depends on the clinical or scientific question. Furthermore, this study should provide a basis for further investigations analyzing the CA.

Emerging Mechanisms in the Pathogenesis of Menière's Disease: Evidence for the Involvement of Ion Homeostatic or Blood-Labyrinthine Barrier Dysfunction in Human Temporal Bones.

Analysis of human temporal bone specimens of patients with Menière's disease (MD) may demonstrate altered expression of gene products related to barrier formation and ionic homeostasis within cochlear structures compared with control specimens. MD represents a challenging otologic disorder for investigation. Despite attempts to define the pathogenesis of MD, there remain many gaps in our understanding, including differences in protein expression within the inner ear. Understanding these changes may facilitate the identification of more targeted therapies for MD. Human temporal bones from patients with MD (n = 8) and age-matched control patients (n = 8) were processed with immunohistochemistry stains to detect known protein expression related to ionic homeostasis and barrier function in the cochlea, including CLDN11, CLU, KCNJ10, and SLC12A2. Immunofluorescence intensity analysis was performed to quantify protein expression in the stria vascularis, organ of Corti, and spiral ganglion neuron (SGN). Expression of KCNJ10 was significantly reduced in all cochlear regions, including the stria vascularis (9.23 vs 17.52, p = 0.011), OC (14.93 vs 29.16, p = 0.014), and SGN (7.69 vs 18.85, p = 0.0048) in human temporal bone specimens from patients with MD compared with control, respectively. CLDN11 (7.40 vs 10.88, p = 0.049) and CLU (7.80 vs 17.51, p = 0.0051) expression was significantly reduced in the SGN. The results of this study support that there may be differences in the expression of proteins related to ionic homeostasis and barrier function within the cochlea, potentially supporting the role of targeted therapies to treat MD.

Temporal bone phantom for decoupled cochlear implant electrode insertion force measurement

Abstract In research on cochlear implants, preclinical testing of newly developed electrode arrays and surgical tools is an essential procedure, which requires the availability of a suitable testing environment. For this purpose, human temporal bone specimens are most realistic, but their availability is limited and additional parameters such as insertion forces are hardly measurable. Therefore, the aim of this study was to develop a temporal bone phantom with realistic anatomical structures for intracochlear force measurement. The temporal bone was segmented from CBCT data of a human cadaver head. The segmented model was 3D printed with an additional artificial skin layer to enable the simulated use of surgical instruments such as a self-retaining retractor. A mechanically decoupled artificial cochlear model was realistically positioned within the temporal bone and was furthermore attached to a force sensor. The usability of the phantom was evaluated by performing automated EA insertions using an automated hydraulic insertion device. The experiments showed that the insertion forces within the cochlea could be measured without interferences from surrounding structures. Moreover, the artificial skin provided a rigid interface for the insertion tool. The new phantom is a realistic testing and training platform for cochlear implant electrode insertions with the advantage of measureable insertion forces.

Preclinical evaluation of a tool for insertion force measurements in cochlear implant surgery

PurposeTrauma that may be inflicted to the inner ear (cochlea) during the insertion of an electrode array (EA) in cochlear implant (CI) surgery can significantly decrease the hearing outcome of patients with residual hearing. Interaction forces between the EA and the cochlea are a promising indicator for the likelihood of intracochlear trauma. However, insertion forces have only been measured in laboratory setups. We recently developed a tool to measure the insertion force during CI surgery. Here, we present the first ex vivo evaluation of our tool with a focus on usability in the standard surgical workflow.MethodsTwo CI surgeons inserted commercially available EAs into three temporal bone specimens. The insertion force and the orientation of the tool were recorded together with camera footage. The surgeons answered a questionnaire after each insertion to evaluate the surgical workflow with respect to CI surgery.ResultsThe EA insertion using our tool was rated successful in all 18 trials. The surgical workflow was evaluated to be equivalent to standard CI surgery. Minor handling challenges can be overcome through surgeon training. The peak insertion forces were 62.4 mN ± 26.7 mN on average. Peak forces significantly correlated to the final electrode insertion depth, supporting the assumption that the measured forces mainly correspond to intracochlear events and not extracochlear friction. Gravity-induced forces of up to 28.8 mN were removed from the signal, illustrating the importance of the compensation of such forces in manual surgery.ConclusionThe results show that the tool is ready for intraoperative use. In vivo insertion force data will improve the interpretability of experimental results in laboratory settings. The implementation of live insertion force feedback to surgeons could further improve residual hearing preservation.

Drilling accuracy evaluation of a mouldable surgical targeting system for minimally invasive access to anatomic targets in the temporal bone.

Minimally invasive cochlear implant surgery using a micro-stereotactic surgical targeting system with on-site moulding of the template aims for a reliable, less experience-dependent access to the inner ear under maximal reduction of trauma to anatomic structures. We present an accuracy evaluation of our system in ex-vivo testing. Eleven drilling experiments were performed on four cadaveric temporal bone specimens. The process involved preoperative imaging after affixing the reference frame to the skull, planning of a safe trajectory preserving relevant anatomical structures, customization of the surgical template, execution of the guided drilling and postoperative imaging for determination of the drilling accuracy. Deviation between the drilled and desired trajectories was measured at different depths. All drilling experiments were successfully performed. Other than purposely sacrificing the chorda tympani in one experiment, no other relevant anatomy, such as facial nerve, chorda tympani, ossicles or external auditory canal were harmed. Deviation between the desired and achieved path was found to be 0.25 ± 0.16mm at skulls' surface and 0.51 ± 0.35mm at the target level. The closest distance of the drilled trajectories' outer circumference to the facial nerve was 0.44mm. We demonstrated the usability for drilling to the middle ear on human cadaveric specimen in a pre-clinical setting. Accuracy proved to be suitable for many applications such as procedures within the field of image-guided neurosurgery. Promising approaches to reach sufficient submillimetre accuracy for CI surgery have been outlined.

Morphometric Analysis and Linear Measurements of the Scala Tympani and Implications in Cochlear Implant Electrodes.

The objective of this study was to perform detailed height and cross-sectional area measurements of the scala tympani in histologic sections of nondiseased human temporal bones and correlate them with cochlear implant electrode dimensions. Previous investigations in scala tympani dimensions have used microcomputed tomography or casting modalities, which cannot be correlated directly with microanatomy visible on histologic specimens. Three-dimensional reconstructions of 10 archival human temporal bone specimens with no history of middle or inner ear disease were generated using hematoxylin and eosin histopathologic slides. At 90-degree intervals, the heights of the scala tympani at lateral wall, midscala, and perimodiolar locations were measured, along with cross-sectional area. The vertical height of the scala tympani at its lateral wall significantly decreased from 1.28 to 0.88 mm from 0 to 180 degrees, and the perimodiolar height decreased from 1.20 to 0.85 mm. The cross-sectional area decreased from 2.29 (standard deviation, 0.60) mm 2 to 1.38 (standard deviation, 0.13) mm 2 from 0 to 180 degrees ( p = 0.001). After 360 degrees, the scala tympani shape transitioned from an ovoid to triangular shape, corresponding with a significantly decreased lateral height relative to perimodiolar height. Wide variability was observed among the cochlear implant electrode sizes relative to scala tympani measurements. The present study is the first to conduct detailed measurements of heights and cross-sectional area of the scala tympani and the first to statistically characterize the change in its shape after the basal turn. These measurements have important implications in understanding locations of intracochlear trauma during insertion and electrode design.

Abstract Number ‐ 119: Stent‐Coil Embolization Of A High Riding Jugular Bulb For Symptomatic Pulsatile Tinnitus

Introduction Tinnitus affects millions of people worldwide and in a significant number of people, tinnitus can be severe enough to impact day‐to‐day life. Various diseases can manifest with tinnitus, including atherosclerotic disease, AVMs, Meniere’s disease, IIH, medication toxicity, and neoplasms. Jugular bulb diverticula are a significant contributor to the incidence of persistent tinnitus. One study of 1579 temporal bone specimens, 8.2% were found to have high‐riding jugular bulbs. Other sources demonstrate a prevalence of 6% in the population. Another study demonstrated a high‐riding jugular bulb in 2.4‐7% of temporal bones, a 5 times higher prevalence of a high‐jugular bulb in patients with ear related symptoms, and tinnitus in 22% of patients in a 730 cohort who presented to otolaryngology. We present 3 cases of jugular bulb diverticula causing debilitating tinnitus and their subsequent treatment with stent‐assisted coiling. Methods Retrospective chart review of patients who presented with symptoms of pulsatile tinnitus, noted to have a jugular bulb diverticulum on cerebral venogram, who underwent stent‐assisted coil embolization. Results A 71‐year‐old male with a history of migraines presented with nausea and right‐sided tinnitus that worsened on lying down. The persistence of symptoms prompted further investigation with a catheter venogram which demonstrated a high‐riding right jugular bulb measuring 10.37 mm x 8.61 mm. The patient underwent stent‐assisted coiling and embolization with improvement in his symptoms. A 57‐year‐old male with recent history of right ischemic infarct secondary to intracranial atherosclerosis had worsening left sided pulsatile tinnitus over one year to the point where it prevented sleep, waking him hourly. A CT‐Venogram revealed a left jugular bulb diverticulum measuring 5.33×5.02 mm. A cerebral angiogram and venogram confirmed this diagnosis and ruled out an AVM/dAVF. Stent‐assisted coiling resulted in immediate relief. The above patients were treated with a Zilver stent (Cook Medical, Bloomington, IN) and Target Coils (Stryker Neurovascular, Kalamazoo, MI). A 40‐year‐old woman presented with severe abrupt‐onset pulsatile right‐sided tinnitus and associated hearing loss, without any associated relieving factors. Due to the severity of her symptoms, she goes to counseling. A cerebral venogram revealed a right internal jugular diverticulum measuring 6.73 mm x 14.5 mm, without any associated dural sinus stenosis. She is scheduled for stent assisted coil embolization. Conclusions High‐riding jugular bulb or jugular diverticulum should be suspected as a potential and treatable cause of pulsatile tinnitus when other diagnoses have been ruled out. Our case series demonstrates that stent assisted coil embolization is safe and effective in relieving tinnitus and hearing loss, which can be debilitating in many cases.

Excursus in Chorda-Facial Angle Variation in Cochlear Implant Surgery: Cadaveric Temporal Bone Study.

Facial recess approach through posterior tympanotomy is the most common & best appraoch for facilitating Cochlear Implant surgery through the round window. Sacrificing Chorda tympani nerve can be avoided by proper understanding of the anatomy of the Facial Recess & Chorda-Facial angles. Hence it is important to know the Chorda-Facial angle to prevent injury in Facial recess approach during Cochlear Implant surgery. Objective This study is done to know the Chorda-Facial angle variation with Round Window visibility during the Facial recess approach which is of relevance in Cochlear Implant surgery. Methods Thirty adult normal wet human cadaveric temporal bones were studied by performing by Posterior Tympanotomy & Facial Recess approach by using ZEISS microscope. Photographs were taken by digital camera of 26 megapixel, imported into computer, then Chorda-Facial angle were measured by Digimizer software & mean angle was calculated. Results The mean angle between the facial nerve & chorda tympani nerve was 20.232°. Bifurcation of chorda tympani nerve at the level of origin itself from the vertical segment of facial nerve was found in 6 Temporal bones out of 30. Round window visibility was noted in all 30 temporal bone specimens (100%). Conclusion The wide Chorda-Facial angle variations, especially the narrowest angle should be known to the otologist in particular to the Cochlear Implant surgeon, which may help avoid inadvertent damage to the CTN in facial recess approach during Cochlear Implant surgery & use diamond burr size of 0.6mm or 0.8mm.