Ultra-high-resolution CT of the temporal bone: The end of stapes prosthesis dimensional error and correlation with patient symptoms

PURPOSE

To describe the reliability of ultra-high-resolution computed tomography (UHR-CT) in the measurement of titanium stapes prostheses using manufacturer data as a reference.

MATERIALS AND METHODS

This retrospective study included patients treated by stapedectomy with titanium prostheses who underwent UHR-CT between January 2020 and October 2023. Images were acquired using an ultra-high-resolution mode (slice thickness: 0.25 mm; matrix, 1024 × 1024). Two radiologists independently evaluated the length, diameter, and intra-vestibular protrusion of the prosthesis. Post-operative air-bone gaps (ABGs) were recorded.

RESULTS

Fourteen patients were enrolled (mean age, 44.3 ± 13.8 [SD] years, 9 females), resulting in 16 temporal bone UHR-CTs. The exact length was obtained in 81.3 % (n = 13/16) and underestimated by 0.1 to 0.3 mm in the remaining 18.7 % (n = 3/16) CT scans for both readers (mean misestimation: -0.02 ± 0.06 [SD] mm, overall underestimation of 0.43 %). The exact diameter was reported in 75 % (n = 12/16) and 87.5 % (n = 14/16) of the CT scans for readers 1 and 2, respectively, and was off by 0.1 mm in all discrepancies (mean misestimation: 0.01 ± 0.04 [SD] mm, overall overestimation of 2.43 %). Intravestibular prosthesis protrusion was of 0.5 ± 0.43 [SD] mm (range: 0-1) and 0.49 ± 0.44 [SD] mm (range: 0-1.1) for readers 1 and 2, respectively, and did not correlate with ABGs (r = 0.25 and 0.22; P = 0.39 and 0.47 for readers 1 and 2, respectively). Intra and interobserver agreements were excellent.

CONCLUSION

UHR-CT provides 99.6 % and 97.6 % accuracy for prosthesis length and diameter measurements, respectively.

Congenital Absence of Stapes Suprastructure and Footplate: A Case Report

INTRODUCTION

Congenital ossicular chain anomalies are rare conductive hearing loss conditions that remain difficult to diagnose even with high-resolution computed tomography (CT). The preoperative diagnosis is helpful for surgical planning and counseling patients regarding treatment outcomes.

CASE PRESENTATION

We report a case involving a 14-year-old boy presenting with left conductive hearing loss without history of trauma for 5 years, physical examination showed normal otoscopic examination bilaterally and high-resolution CT showed absent of stapes suprastructure and footplate. Subsequent diagnosis was done via endoscopic middle ear exploration which revealed an absent long process of the incus, stapes suprastructure and footplate, but with intact oval window membrane. The residual incus was removed, and a tragal perichondrium graft was used over the oval window. A total ossicular replacement prosthesis was placed between the malleus and oval window to repair the chain. Postoperatively, the patient had no complications. Preoperative pure tone average revealed an air/bone result of 52/8 dB. Follow-up after surgery at 6 months showed a pure tone average air/bone result of 15/3 dB. The air-bone gap was reduced from 44 to 12 dB.

CONCLUSION

Congenital absence of the stapes suprastructure and footplate remains a rare condition compared to the myriad of middle ear anomalies in the literature.

Study of Morphological and Anthropometric Features of Human Ear Ossicles

To study the morphology and anthropometry of human ear ossicles from cadaveric temporal bone and to study the variations of the human ossicles from ossiculoplasty point of view. 38 sets of ear ossicles were collected, each containing malleus, incus and stapes, from temporal bone dissection done in Vasantrao Pawar medical college, Nashik. They were studied under microscope & anthropometrical, morphological evaluation done. Malleus showed variations in handle where 61% were straight and 39% curved. Weight of malleus ranged from 0.03-0.06 gm. The length ranged from 5.5 to 8.2 mm. Incus showed morphological variation in lenticular process which was present in 73% incii. Weight of incus ranged from 0.04 to 0.09 gm, average length of long process 3.5 mm, width of body 4 mm. In stapes variations was seen with head of stapes which was absent in 21% bones. With increasing awareness about postop hearing status, this study will add up in knowledge of morphological and anthropometric variations that exists in Indian population, help otologists to understand middle ear dynamics better which will improve results of ossiculoplasty.

Utility of machine learning for identifying stapes fixation on ultra-high-resolution CT

PURPOSE

Imaging diagnosis of stapes fixation (SF) is challenging owing to a lack of definite evidence. We developed a comprehensive machine learning (ML) model to identify SF on ultra-high-resolution CT.

MATERIALS AND METHODS

We retrospectively enrolled 109 participants (143 ears) and divided them into the training set (115 ears) and test set (28 ears). Stapes mobility (SF or non-SF) was determined by surgical inspection. In the ML analysis, rectangular regions of interest were placed on consecutive axial slices in the training set. Radiomic features were extracted and fed into the training session. The test set was analyzed using 7 ML models (support vector machine, k nearest neighbor, decision tree, random forest, extra trees, eXtreme Gradient Boosting, and Light Gradient Boosting Machine) and by 2 dedicated neuroradiologists. Diagnostic performance (sensitivity, specificity and accuracy, with surgical findings as the reference) was compared between the radiologists and the optimal ML model by using the McNemar test.

RESULTS

The mean age of the participants was 42.3 ± 17.5 years. The Light Gradient Boosting Machine (LightGBM) model showed the highest sensitivity (0.83), specificity (0.81), accuracy (0.82) and area under the curve (0.88) for detecting SF among the 7 ML models. The neuroradiologists achieved good sensitivities (0.75 and 0.67), moderate-to-good specificities (0.63 and 0.56) and good accuracies (0.68 and 0.61). This model showed no statistical differences with the neuroradiologists (P values 0.289-1.000).

CONCLUSIONS

Compared to the neuroradiologists, the LightGBM model achieved competitive diagnostic performance in identifying SF, and has the potential to be a supportive tool in clinical practice.

Absent Stapedial Tendon: Imaging Features of an Underrecognized Entity : Clinical Neuroradiology

PURPOSE

Congenital absence of the stapedial tendon is a rare entity with characteristic imaging findings, which can go unrecognized due the scarcity of the diagnosis and limited previous description in the imaging literature. We aim to characterize the imaging features of this entity.

METHODS

A series of 9 cases with surgical confirmation of stapedial tendon absence were retrospectively reviewed and the most common abnormalities on high resolution computed tomography (CT) of the temporal bone described.

RESULTS

Congenital fixation of the stapes footplate was present in nearly all cases of stapedial tendon absence (n = 8, 89%), a clinically important association because the stapes footplate abnormality was not detectable on preoperative CT. Absence or hypoplasia of the pyramidal eminence and aperture was identified in almost all cases (n = 8, 89%), which may be the sole imaging finding to suggest stapedial tendon absence and associated stapes footplate fixation prior to surgery.

CONCLUSION

The most reliable indicator of stapedial muscle absence on temporal bone CT is the absence or hypoplasia of the pyramidal eminence and aperture. Importantly, most patients had congenital stapes footplate fixation confirmed intraoperatively with a normal stapes footplate on CT, meaning the pyramidal eminence/aperture abnormality was the only preoperative imaging finding that could have suggested the footplate fixation.

Comparison of dislocation rates of Teflon and Titanium stapes prostheses: a retrospective survival analysis on 855 patients

BACKGROUND

Stapes prosthesis dislocation is the first cause of revision stapes surgery. To our knowledge, there is no data about stability of the incus attachment of manual crimped prosthesis of different materials. This study aimed to compare the dislocation incidence between titanium and fluoroplastic stapes prostheses.

METHOD

A monocentric retrospective cohort study was conducted between January 2013 and June 2022 in a tertiary-care center. All patients that underwent a primary stapes surgery with manually crimped fluoroplastic or titanium prostheses were included. Prosthesis dislocation from the incus was identified intraoperatively or with CT scan. The incidence of stapedial prosthesis dislocation over time was estimated using the Kalbfleisch and Prentice survival analysis method. Other indications for revision surgery prior to prosthesis dislocation were considered as competing events. Differences in the cumulative incidence functions between the fluoroplastic group and the titanium group was assessed using the Gray's test.

RESULTS

Eight hundred and fifty-five patients underwent primary stapes surgery during the study period. Fluoroplastic prosthesis was used in 758 (88.7%) cases and titanium prosthesis in 97 (11.3%) cases. Median follow-up was 51.7 months (28.4-80.1). Dislocation was observed in 23 (3.0%) patients with fluoroplastic prosthesis and none (0.0%) in the titanium group. The probability of prosthesis dislocation at two years after surgery was 3.5% in the Teflon group and 0.0% in the Titanium group. No significant difference was found in the cumulative incidence of prosthesis dislocation between the fluoroplastic group and the titanium group (p = 0.12).

CONCLUSIONS

Despite lack of statistical power, our results suggest a trend in a more stable incus attachment of manually crimped titanium stapes prosthesis compared to fluoroplastic over time. Further prospective randomized studies could be valuable to assess our findings.

Diagnostic Value of the Air-Bone Threshold Gap in Stapes Fixation

INTRODUCTION

The Carhart notch is a well-known sign of stapes fixation. However, previous studies have reported that the Carhart notch is not specific to stapes fixation and is also present in other middle ear diseases. Therefore, this study investigated the diagnostic value of threshold gap between air conduction and bone conduction (ABG) for stapes fixation, instead of the bone conduction dip representing the Carhart notch.

METHODS

A total of 199 ears that underwent exploratory tympanotomy were enrolled in this retrospective study. They were categorized into three groups according to surgical findings: stapes fixation (SF), other ossicle fixation (OF), and chain disconnection (CD). Preoperative pure-tone audiograms and impedance audiograms were compared between the groups.

RESULTS

The incidence of the Carhart notch did not differ between the groups. The ABG at 2,000 Hz showed a good diagnostic performance for distinguishing between the SF and CD groups (area under the curve, AUC = 0.816, p < 0.001), but poor performance for distinguishing between the SF and OF groups (AUC = 0.662, p = 0.003). Bone conduction at 2,000 Hz showed a moderate performance for distinguishing between the SF and CD groups (AUC = 0.707, p < 0.001) and did not show statistically significant results for distinguishing between the SF and OF groups (AUC = 0.594, p = 0.080). The tympanic membrane compliance was significantly higher in the CD group than in the SF group (p = 0.001).

CONCLUSIONS

The Carhart notch was not a specific finding of SF. The sensitivity and specificity of ABG ≤15 dB at 2,000 Hz for distinguishing between SF and CD were 60.4% and 89.2%, respectively. To prepare for surgical interventions in patients with conductive hearing loss but a normal tympanic membrane, clinicians should comprehensively consider these results.

Can the unmodified incus be used for a simpler, more cost-effective functional ossicular chain reconstruction? A retrospective clinical study

OBJECTIVE

To evaluate patients' hearing outcomes after ossicular chain reconstruction using unmodified autologous incus.

METHODS

A single-centred, retrospective study of patients who underwent incus interposition between June 2010 and October 2017 was conducted at a Dutch secondary referral centre. This paper describes a chart review of patients who presented with erosion of the long process of the incus due to atelectasis or cholesteatoma who were treated with an unmodified incus interposition. The main outcome measures were: post-operative air-bone gap and level of air-bone gap closure.

RESULTS

Thirty-three ears of 32 patients were included. Follow-up duration ranged from six weeks to seven years. A mean post-operative air-bone gap under 25 dB was considered successful; this was achieved in 25 patients (76 per cent), 20 (91 per cent) in the partial ossicular reconstruction prosthesis group and 5 (45 per cent) in the total ossicular reconstruction prosthesis group. This difference was statistically significant (p = 0.007).

CONCLUSION

Successful preservation and improvement of hearing was observed in most patients. As expected, the closure rate in the partial ossicular reconstruction prosthesis group was better. Longer follow-up studies with larger case numbers are needed to assess whether further reconstruction techniques are necessary.

Rates of Sensorineural Hearing Loss and Revision Surgery After Stapedotomy: A Single-institution Experience Using the Nitinol Prosthesis

Background

Historically, stapedectomy complication rates are quoted as 1% profound postoperative sensorineural hearing loss (SNHL), 5%-10% nonprofound SNHL, and 5%-10% revision surgery.

Objective

We sought to reassess rates of post-stapedotomy complications based on our experience using contemporary surgical technique.

Methods

A retrospective case series was carried out at an academic tertiary referral center. Adult patients undergoing stapedotomy from 2013 to 2020 were included. Primary outcomes were rates of hearing loss and revision surgery. Rates of dizziness, tinnitus, dysgeusia, and proportions of patients who achieved air-bone gap (ABG) closure at 8-12 weeks postoperatively were also assessed.

Results

Four hundred sixty-eight stapedotomies in 399 patients with a median follow-up duration of 99 days (range, 11-5134) were reviewed. One patient (0.21%) suffered profound SHNL and 15 (3.20%) patients suffered nonprofound SNHL. The revision rate for stapedotomies from our institution was 4.49% (21 total revision surgeries). In 277 operations (59.19%), the patient had closure of the ABG within 10 dB. A further 132 (28.21%) had closure of the ABG between 10 and 20 dB. Air pure-tone audiometry scores improved by an average of 25.03 dB. Eighty-three (17.74%) patients complained of postoperative dizziness, which resolved by the time of the first follow-up appointment in all but 26 (5.56%). Seventeen patients (3.63%) complained of tinnitus, and 22 (4.70%) complained of dysgeusia.

Conclusions

SNHL, complications, and revision rates for stapedotomy in the modern era may be substantially lower than those currently presented to patients based on classic techniques and historical data.

Removal and Repositioning of a Piston Wire Prosthesis that Entered the Vestibule Secondary to Trauma in a Patient who Underwent Stapedotomy

Otosclerosis is a common cause of adult-onset hearing impairment, and stapedotomy is often performed as surgical treatment. Several studies have reported the complications of stapedotomy surgery; piston wire prosthesis (PWP) disruption or dislocation secondary to indirect force attributable to head trauma is described in many patients. Most PWPs that get displaced are slanted or are completely dislodged from the stapedotomy site and lodged within the middle ear. PWP dislocation into the vestibule is extremely rare. A 65-year-old woman who was involved in a traffic accident underwent computed tomography, which revealed a right-sided PWP in the vestibule. Two weeks after the accident, we observed conductive hearing loss associated with a large air-bone gap (ABG, 47 dB) accompanied by spontaneous nystagmus directed to the right without any change in nystagmus following changes in head or body position. She underwent endoscopic exploratory tympanotomy under general anesthesia, 23 days after the injury. We gently pulled the PWP from the vestibule and repositioned it at its original site with a length of 5.2 mm on the long process of the incus. Pure tone audiometry performed 8 months postoperatively showed a decrease in the ABG from 47 to 10 dB without any complications.

Comparison of different oval window sealing materials in stapes surgery: systematic review and meta-analysis

OBJECTIVE

To compare the efficacy and safety characteristics of different materials used for oval window sealing during stapedotomy.

METHODS

A systematic review was conducted according to the PRISMA guidelines. Published international English literature from January 1, 2000 to December 2021 was screened, checking for studies that compared different materials utilization in patients undergoing stapedotomy surgery for otosclerosis or congenital stapes fixation. Data related to the efficacy and safety of each material were extracted. The primary outcome measure was the air-bone gap (ABG) closure after surgical intervention.

RESULTS

Six studies were included in the metanalysis. Because of the heterogeneity of the treatments adopted, we assessed the use of the fat compared to all other treatments, and the use of the gelfoam compared to all other treatments. In the former analysis (fat vs others) we did not identify differences in ABG closure between the groups (p = 0.74), with a low heterogeneity of the results (I² = 28.36%; Hedge's g = 0.04, 95% CI - 0.19 0.27); similarly, we did not identify differences between the use of gelfoam and other treatments (p = 0.97), with a low heterogeneity of the results (I² = 28.91%; Hedge's g = 0.00, 95% CI - 0.20 0.21).

CONCLUSIONS

Numerous options are available for oval window sealing during stapedotomy, with acceptable safety and effectiveness profiles. Based on the current data, no definitive recommendation can be made regarding the choice of one material over another, and the convenience of sealing over no sealing at all.

The Stapes in Otosclerosis: Osteoarthritis of an Ear Ossicle

Otosclerosis is a pagetoid proliferation of bone remodeling, vascular proliferation, bone resorption and new bone formation in the tympanic region of the temporal bone. The resulting anklyosis of the stapes footplate as it articulates with the oval window is the most common cause of conductive hearing loss in young to middle aged, predominantly Caucasian individuals. The characteristic histologic features have been well documented by autopsy studies of the temporal bone. Although stapedectomy is the surgical treatment for otosclerosis, the stapes specimen may be submitted for gross examination only or not examined at all. A retrospective study of 73 stapedectomy specimens (2008-2019) not including the stapes footplate. Clinical features from the electronic medical record as well as standard histologic sections from surgical specimens were reviewed. Neither the stapedal head nor crura showed histologic features of otosclerosis. There was mild osteoarthritis affecting the head, possibly as a consequence of persistent ossicular vibration superimposed on the ankylosed rigidity. The most common changes were surface fissuring (65%), cartilaginous erosion (49%) and irregularity of the osteochondral interface (51%). An occasional osteophyte (8%) was observed. The ear ossicles, embryologically analogous to long bones of the extremities, develop via endochondral ossification and exhibit articular surfaces of hyaline cartilage. The present observations suggest that a consequence of otosclerotic ankylosis is osteoarthritis of the stapedal head. In this study, the histological features could not be correlated with the severity of hearing loss or duration of clinical disease.

Conventional approaches versus laser CO2 surgery in stapes surgery: a multicentre retrospective study

PURPOSE

To analyze and compare surgical and audiological outcomes of conventional approaches versus laser CO2 surgery in stapes surgery.

METHODS

333 patients who underwent stapes surgery were enrolled in the study; the patient population was divided into three groups: group 1: 170 patients treated with conventional stapedotomy with manual microdrill (average age 49.13 years); group 2: 119 patients treated with conventional stapedotomy with electrical microdrill (average age 51.06 years); group 3: 44 patients (average age 50.4 years) who underwent CO2 laser stapedotomy. Intra-operative, postoperative outcomes and audiological results were investigated.

RESULTS

The average surgical time of laser CO2 surgery was longer than for other surgical procedures. No statistical differences emerged in post-operative abnormal taste sensation. There was also no difference in postoperative dizziness. Air-bone gap (ABG) went down from 29.7 ± 10 dB (group 1) and 27.32 ± 9.20 (group 2) to 10 ± 6.9 dB (group 1) and 10.7 ± 6.03 dB (group 2). In group 3 the preoperative ABG was lowered from 28.3 ± 10.1 to 11.8 ± 10.9, with a statistical difference in auditory recovery (p = 0.0001); The group of patients treated with laser CO2 showed a percentage of patients with an ABG closure of between 0 and 10 dB higher than in the group treated with manual microdrills (77.2% vs. 60%, respectively; p = 0.03).

CONCLUSION

Overall surgical results of CO2 laser and conventional stapedotomy are comparable without any significant difference; however, the group treated with CO2 laser appears to have a percentage of patients with an ABG closure 0-10 dB higher than the group treated using the conventional technique.

Stapes visualization by ultra-high resolution CT in cadaveric heads: A preliminary study

PURPOSE

This study aimed to assess stapes visualization using an ultra-high resolution computed tomography (U-HRCT).

METHOD

Sixty ears from 30 cadaveric human heads were scanned by both U-HRCT and 128-section multislice CT (MSCT) with clinical parameters. Image quality of the stapes head, anterior and posterior crura, footplate, incudostapedial joint and stapedial muscle within the pyramidal eminence was scored using a 3-point Likert scale. Linear measurements of the stapes configuration were performed on U-HRCT.

RESULTS

The interobserver agreement for image qualitative score on U-HRCT was good to excellent (interobserver agreement coefficients 0.65-0.86). With the exception of the stapes head, U-HRCT achieved significantly higher qualitative scores than MSCT across all anatomical structures (Ps < 0.05). The total height of the stapes was measured to be 3.48 ± 0.33 mm. The height and width of the obturator foramen were 1.77 ± 0.28 mm and 2.19 ± 0.33 mm, respectively. The widths of the anterior and posterior crura were 0.20 ± 0.06 mm and 0.22 ± 0.06 mm, respectively. The thickness of the footplate was 0.22 ± 0.06 mm, and the angle of the incudostapedial joint was 95.91 ± 10.69°.

CONCLUSIONS

U-HRCT is capable of delineating fine structures of the stapes and provides linear data on dimensions of the stapes, which could be helpful for detecting stapes disease and making individualized surgical plans in the clinical setting.

Post-stapedotomy reparative granuloma following use of acellular porcine small intestinal submucosa

PURPOSE

There have been multiple proposed etiologies of reparative granuloma following stapes surgery. In this report, we present the first case of post-stapedectomy reparative granuloma following the use of Biodesign (Cook Medical, Bloomington, IN) otologic graft material, an acellular matrix derived from porcine small intestinal submucosa, and review the literature of post-stapes surgery reparative granuloma.

PATIENT

50-year-old woman who developed a reparative granuloma following stapedotomy with acellular porcine intestinal submucosa presenting with profound hearing loss and vertigo.

INTERVENTION

Middle ear exploration with excision of granuloma and revision stapedotomy.

MAIN OUTCOME MEASURES

Audiologic outcomes as measured by pure-tone air and bone conduction thresholds and word recognition scores. Improvement in vertigo.

MAIN FINDINGS

Surgical excision of the reparative granuloma with revision stapedotomy resolved vertigo. Hearing has improved progressively postoperatively.

CONCLUSIONS

We report the first case of post-stapedotomy reparative granuloma following the use of acellular porcine intestinal submucosa. Although exact etiology cannot be determined from a single case report, this illustrates the need for careful use of novel foreign graft material. This case additionally confirms that removal of granuloma and inciting materials can salvage serviceable hearing.

Totally implantable active middle-ear implants: a large, single-surgeon cohort

OBJECTIVES

This study aimed to evaluate hearing outcomes and device safety in a large, single-surgeon experience with the totally implantable active middle-ear implants.

METHODS

This was a retrospective case series review of 116 patients with moderate-to-severe sensorineural hearing loss undergoing implantation of active middle-ear implants.

RESULTS

Mean baseline unaided pure tone average improved from 57.6 dB before surgery to 34.1 dB post-operatively, signifying a mean gain in pure tone average of 23.5 dB (p = 0.0002). Phonetically balanced maximum word recognition score improved slightly from 70.5 per cent to 75.8 per cent (p = 0.416), and word recognition score at a hearing level of 50 dB values increased substantially from 14.4 per cent to 70.4 per cent (p < 0.0001). Both revision and explant rates were low and dropped with increasing surgeon experience over time.

CONCLUSION

This study showed excellent post-operative hearing results with active middle-ear implants with regard to pure tone average and word recognition score at a hearing level of 50 db. Complication rates in this case series were significantly lower with increasing experience of the surgeon. Active middle-ear implants should be considered in appropriate patients with moderate-to-severe sensorineural hearing loss who have struggled with conventional amplification and are good surgical candidates.

A New Stapes-Head Coupler for the Vibrant Soundbridge System

INTRODUCTION

The Vibrant Soundbridge (MED-EL Medical Electronics, Austria) is an active middle ear implant with a floating mass transducer (FMT) for patients with conductive, sensorineural, or mixed hearing loss. While the FMT is vertically aligned above the stapes head (SH) with the current Vibroplasty Clip coupler (MED-EL Medical Electronics), the new SH coupler was developed to mount the FMT on the inferior side of the stapes and to fit in the reduced middle ear space after canal-wall-down mastoidectomy.

METHODS

Using 11 human cadaveric temporal bones (TBs), placements of the new SH couplers on the stapes were examined, and effective stimuli to the cochlea were evaluated by measuring piston-like motion of the stapes footplate with a current of 1 mA on the FMT. The results were assessed in comparison with the Vibroplasty Clip coupler.

RESULTS

The new SH coupler showed perfect coupling on the stapes in 9 out of 11 TBs. A small gap between the SH and the plate of the connection link part was unavoidable in 2 TBs but had negligible effect on vibrational motion of the stapes. Vibrational motion of the stapes with the new SH coupler was reduced at frequencies above 3 kHz compared to the corresponding motion with the current Vibroplasty Clip coupler, but the relative attenuation over all 11 cadaveric temporal bones was <10 dB.

CONCLUSIONS

The new SH coupler provides an alternative with more stable fixation when placement of the current Vibroplasty Clip coupler is limited due to insufficient space after canal-wall-down mastoidectomy, while still delivering effective stimuli to the cochlea.

Analysis of forces during robot-assisted and manual manipulations of mobile and fixed footplate in temporal bone specimens

PURPOSE

To evaluate the forces involved in different manipulations, manual or robot-assisted, applied to the ossicular chain, on normal temporal bones and on an anatomical model of otosclerosis.

METHODS

Thirteen cadaveric temporal bones, with mobile footplates or with footplates that were fixed using hydroxyapatite cement, were manipulated, manually or using a robotic arm (RobOtol®). "Short contact" of a mobile footplate was the weakest interaction on the incus. "Long contact" was the same manipulation held for 10 s. "Mobilization" was the smallest visualized movement of the mobile footplate, or the movement necessary to regain mobility of the fixed footplate. A six-axis force sensor (Nano17, ATI) measured the maximal peak of forces, summation of forces applied, and yank.

RESULTS

Maximal forces during short (~4 mN) and long contact (~15 mN) were similar for manual and robot-assisted manipulations. For manual manipulation, yank measured during long contact was twice as high compared to robot-assisted manipulation: 6 ± 2.4 (n = 5) and 3 ± 1.3 mN/s (n = 5), respectively (mean ± SD, p < 0.02). For mobilization of the mobile footplate, maximal forces during mobilization were similar during manual and robot-assisted manipulations, respectively: 12 ± 2.5 (n = 6) and 19 ± 7.6 mN (n = 7). Compared with mobilization of a mobile footplate, mobilization of a fixed footplate required ~ 60 and ~ 27 times higher maximal forces for manual and robot-assisted manipulations, respectively: 724 ± 366.4 and 507 ± 283.2 mN. Yank was twice as high during manual manipulation compared to robot-assisted manipulation (p < 0.05).

CONCLUSION

Robot-assisted manipulation of the ossicular chain was reliable. Our anatomical model of otosclerosis was successfully developed requiring higher forces for stapes mobilization.

Effect of conservation method on ear mechanics for the same specimen

BACKGROUND AND AIMS

As an alternative to fresh temporal bones, Thiel conserved specimens can be used in the study of ear mechanics. Conserved temporal bones do not decay, permit long-term experiments and overcome problems with limited access to fresh (frozen) temporal bones. Air conduction motion of the tympanic membrane (TM), stapes (ST) and round window (RW) in Thiel specimens is similar to that of fresh specimens according to reports in the literature. Our study compares this motion directly before and after conservation for the same specimens.

METHODS

The magnitude of motion of TM, ST and RW elicited by acoustic stimulation via the external auditory canal was measured using single point laser Doppler vibrometry (LDV) accessed through a posterior tympanotomy. For the initial measurements (10 ears), fresh frozen whole heads were thawed for at least 24 h. Afterwards, the entire whole heads were embalmed according to the Thiel embalming method and measurements were repeated 3 and 12 months later.

RESULTS

The magnitudes of TM, ST and RW motion before and after Thiel conservation differed maximally 10 dB on average. A significant increase in TM motion was observed at low frequencies only after long term conservation (12 months). ST motions decreased significantly between 161 and 5300 Hz after 3 months of Thiel conservation. Over the same time period RW motions decreased significantly between 100 and 161 Hz and 489-788 Hz. The ST and RW motions across all measured frequencies were lower after 3 months by 5.7 dB and 7.1 dB, respectively, without further changes after 12 months of conservation. The mean phase shift between ST and RW motion was only 2.1° for frequencies below 450 Hz.

DISCUSSION AND CONCLUSION

Thiel embalming changes motion of TM after long term conservation. ST and RW motion changed mainly after short term conservation. The phase shifts close to 180° between ST and RW motion indicates that the cochlea was still filled with liquid without air bubbles. The results show that Thiel conserved specimens can be used as an alternative model to fresh frozen preparations with some limitations when studying mechanics of the normal human ear, for example, in implant design.

Microdrill in endoscopic stapes surgery: Is it safe?

PURPOSE

To assess the safety of using a microdrill in endoscopic vs microscopic stapes surgery.

MATERIALS AND METHODS

A retrospective review of 29 adult ears with otosclerosis who underwent either an endoscopic or microscopic approach to microdrill stapedotomy.

PRIMARY OUTCOME

Determine if transcanal endoscopic stapes surgery with the microdrill is as safe as microscopic stapes surgery. Secondary outcome: Bone and air pure-tone averages, air-bone gap, speech discrimination, overall surgical cost, and operative time were measured and analyzed. Complications such as post-operative dysgeusia, vertigo, readmission, revision and hearing loss were noted.

RESULTS

29 patients with otosclerosis were retrospectively reviewed, in total 14 endoscopic and 15 microscopic approaches were included, all performed over one-year period. None of the endoscopic surgeries require conversion to the microscope. No statistically significant audiometric differences between the endoscopic vs microscopic approaches in air pure-tone averages and air-bone gap. There were 82.8% air-bone gap closure to <15 dB with no significant difference in the percent of such closures between the endoscopic (85.7%) and microscopic groups (80%, P = .68). Three prostheses were used: 4.25 mm (17.2%), 4.5 mm (58.6%) and the 4.75 mm (24.1%) smart/eclipse. Endoscopic median operative time was 51 min vs 42 min for microscopic approach (P =.004).

CONCLUSIONS

The endoscopic with microdrill approach is criticized to lack depth perception, especially when using a microdrill to perform in stapedotomies. Our study showcases that using the microdrill use produces minimal differences in outcomes, cost, and is a safe modality to stapes surgery in both approaches.

Titanium prostheses versus stapes columella type 3 tympanoplasty: a comparative prospective study

Introduction

Tympanoplasty is a surgical procedure designed to reconstruct the mechanisms of sound transmission in the middle ear.

Objective

Analyze, from an audiological point of view, patients with chronic otitis media undergoing type 3 tympanoplasty major columella with total ossicular replacement titanium prosthesis or with cartilage graft stapes columella.

Methods

This is a prospective analytical study, carried out at the otorhinolaryngology outpatient clinic in a tertiary care hospital, through the evaluation of 26 patients with chronic otitis media who underwent tympanoplasty using different materials for auditory rehabilitation such as titanium prostheses or cartilage autografts.

Results

There was no statistically significant association between the group factors (cartilage or titanium reconstruction) and preoperative variables. There was no statistically significant association between the postoperative characteristics of the patients and the type of reconstruction. Neither subjective improvement (hearing improvement) nor residual perforation were associated with a type of material. The via factor was the only one that showed a statistically significant difference once air-conduction pathway improved more than bone-conduction pathway, decreasing the air-bone gap.

Conclusion

There was no statistical difference between the two groups in relation to the audiometric improvement. There was hearing improvement in both groups. More studies must be done with a longer follow-up to better evaluate the outcome.

Hyperacusis and stapes surgery: An observation in fifty patients after stapedotomy

Objective

To assess hyperacusis after stapedotomy and its possible influencing factors.

Study design

Prospective, interventional, and longitudinal study.

Setting

A tertiary referral center.

Patients

Fifty consecutive patients (35 females, mean age = 46.8 years).

Intervention

All patients underwent stapedotomy. The validated Portuguese version of the “Hyperacusis Questionnaire” (HQ) was administered before and two weeks and one month after surgery.

Results

No hyperacusis was reported by any patient before surgery. At two weeks after surgery, all patients experienced hyperacusis, with a mean HQ at 16.88 ± 6.54 (range 4–25). One month after surgery, hyperacusis had already resolved in most patients. Gender, preoperative presentation or surgeon had no influence on HQ scores (p > 0.05). Patients with previous contralateral stapedotomy showed lower HQ scores (p = 0.001). Audiological parameters improvement measured at one month after surgery (PTA, SRT and contralateral SRT) were associated with HQ higher scores.

Conclusion

This study confirms that hyperacusis is a common complaint after stapedotomy that usually resolves in one month after surgery. The HQ highest scores were registered among patients with the highest audiological gain after surgery. This suggests that hyperacusis may be a positive prognostic factor for audiological success after stapedotomy.

Malleostapedotomy for otosclerosis, our experience of nitinol piston on twelve patients

Objective

Malleostapedotomy allows to completely by-pass the incus in otosclerosis surgery. Recently its use has been rivaled by hydroxyapatite cement for cases of mild and moderate necrosis of the incus. However, it remains gold standard for cases of extensive necrosis, incus dislocation, or epitympanic fixation. Modern heat-crimping pistons make surgery easier and safer. This study focuses on our experience with this technique.

Methods

Retrospective analysis of patient’s files and pre- and post-operative audiograms, for cases of surgically treated otosclerosis with malleostapedotomy.

Results

Twelve patients underwent malleostapedotomy for otosclerosis between 2011 and 2019. Amongst them there were 10 revision surgeries and 2 primary cases. 75% had incus long-process necrosis, 17% had epitympanic fixation and one had a history of incus transposition. Nine patients (75%) had closure of air-bone gap (ABG) of <10 dB (p < 0.001) and 11 (92%) had a threshold of 20 dB (p < 0.001). Mean pre-operative ABG was 31 dB (15 dB–55 dB), and mean post-operative ABG was 7 dB (0 dB–21 dB; p < 0.001). There was no sensorineural hearing loss nor any other post-operative complication.

Conclusions

Malleostapedotomy is a safe and reliable technique, allowing an ABG closure comparable to conventional incus to vestibule prosthesis. It remains the preferred technique whenever the incus cannot be used.

Stapes stabilizing cartilage graft

PURPOSE

This study aimed to evaluate hearing results in patients with type 3 tympanoplasty using autologous cartilage grafts.

METHODS

The study included patients treated with "stapes stabilizing cartilage graft" (SSCG) and Plastipore partial ossicular replacement prosthesis (PPORP) for hearing reconstruction. Hearing results and complications were assessed and postoperative audiological tests were performed at least 6 months after surgery.

RESULTS

There were 18 patients (5 men, 13 women) in the SSCG group and 12 patients (5 men, 7 women) in the PPORP group. The air conduction threshold changed by 22.4 ± 7.5 dB in the SSCG group, and by 13.2 ± 12.9 dB in the PPORP group (p = 0.022), after hearing reconstruction. The air-bone gap (ABG) changed by 20.1 ± 8.3 dB in the SSCG group and by 16.3 ± 12.3 dB in the PPORP group. Although the change in ABG was greater in the SSCG group than in the PPORP group, the difference was not statistically significant (p > 0.05). No complications were recorded in the SSCG group, whereas two patients experienced a severe vertigo attack after surgery in the PPORP group, which lasted for approximately 2 weeks with conservative management. Extrusion was not encountered in the PPORP group, while extrusion of the titanium partial ossicular replacement prosthesis occurred in one patient in the SSCG group who underwent revision surgery.

CONCLUSIONS

Better hearing outcomes were obtained with SSCG than with PPORP. SSCG can be used as an alternative hearing reconstruction technique in cases of type 3 tympanoplasty.

Promontory osteoma mimicking otosclerosis: case report

OBJECTIVE

This case report presents a middle-ear osteoma mimicking otosclerosis that was located at the promontory. The osteoma was successfully excised using an endoscopic transcanal approach without any complication.

CASE REPORT

A 21-year-old man presented with a 4-year history of progressive conductive hearing loss (47 dB with a 30-dB air-bone gap) with intermittent tinnitus of recent onset in his right ear. Endoscopic transcanal middle-ear exploration showed that an osteoma located on the promontory was restricting the mobility of the stapes by affecting the anterior crus of the stapes. After transcanal resection of the osteoma, pure tone audiometry improved to 23 dB with a 5-dB air-bone gap. Tinnitus resolved spontaneously without any additional treatment.

CONCLUSION

Promontory osteomas, a rare and usually asymptomatic clinical entity, should be taken into consideration in the differential diagnosis in patients with progressive conductive hearing loss and tinnitus with intact stapedial reflexes and normal otoscopic findings.

Anatomic variability of oval window as pertaining to stapes surgery

PURPOSE

The purpose of the study is to study the details of dimensions and shape of oval window in different age groups, sides and genders and their clinical implications. The oval window is a key structure while performing surgeries in relation to stapes. An intricate knowledge of the shape and size of the oval window is important for the reconstruction and fitting of cartilage compatible with the native shape of the oval window.

METHODS

Sixty normal wet cadaveric temporal bones of known age; gender and side were micro-dissected. The maximum height and width of the oval window was measured. The shape of the oval window was noticed.

RESULTS

The mean value for maximum height and width of the oval window was 1.31 ± 0.28 mm and 2.67 ± 0.42 mm, respectively. The height and width of the oval window ranged between 1 mm and 1.5 mm and 2 mm and 3 mm in majority of the cases.  he oval window was found to be oval shaped in 53.3% cases, other shapes such as kidney, D shape, rectangular or trapezoidal were also observed.

CONCLUSIONS

The refined morphometric information of the oval window will help in preoperative assessment and surgical planning of various oval window-related surgical procedures. The knowledge may also help in designing and selecting proper cartilage shoe for the best outcome. Narrow oval window may cause procedural complications and surgeon discomfort in various stapes surgeries.

Results of stapedotomy in otosurgical treatment of adult patients with osteogenesis imperfecta

OBJECTIVE

This is a retrospective study of hearing results and characteristics of osteogenesis imperfecta (OI) patients treated for hearing loss by stapedotomy at tertiary reference center.

METHODS

This study enrolled 20 patients with a clinical diagnosis of OI- (11M:9F). 18 patients (90%) underwent surgery due to hearing loss in the period 2003-16. The audiometric analysis provides the pure tone audiometry results of stapedotomy in adult patients in 2 periods (≤12 months and >12 months). Air-bone gap (ABG), hearing gain (HG), and changes in air and bone conduction thresholds after surgical treatment were analyzed.

RESULTS

In short-time follow-up we noted statistically significant improvement in mean AC thresholds and ABG (p < 0.001 for both), change in mean BC thresholds was statistically negligible. Comparing the observation periods short-term and long-term, it was found that AC thresholds, ABG, HG, ABG closure did not significantly change, although BC thresholds and BC closure deteriorated significantly (p < 0.05).

CONCLUSION

Stapes surgery for OI can be considered as a method of treating the conductive and/or mixed hearing loss suffered by these patients; however, the surgery is more difficult than that for otosclerosis because OI cases often have extremely difficult anatomical conditions. The hearing results of OI stapes surgery differ from typical otosclerosis cases, with the ABG closure not being as good. In addition, sensorineural hearing loss inevitably progresses.

Stapes hypermobility as a possible cause of hyperacusis

OBJECTIVE

Hyperacusis is a reduction of normal tolerances for everyday sounds. Although several publications have been produced demonstrating that minimally invasive surgical procedures may improve patient symptoms, the precise etiology of hyperacusis often remains elusive. This study describes 21 patients, 7 of whom stapes hypermobility is believed to be a mechanical genesis of their hyperacusis symptoms.

STUDY DESIGN

A prospective, repeated-measure single-arm design was used for this study.

SETTING

All patients were evaluated and treated at a tertiary level otologic referral center.

SUBJECTS AND METHODS

21 patients (Cohort A) with severe hyperacusis underwent oval and round window reinforcement. Seven patients (Cohort B) intraoperatively appeared to have subjective hypermobility of the stapes. Additional reinforcement of the stapes superstructure was performed in these patients.

RESULTS

In Cohort A, loudness discomfort level (LDL) values improved on average from 72.7 dB to 81.9 dB. Hyperacusis questionnaire (HQ) scores improved from 30.1 to 14.7. Numeric Rating Scale scores (0-10) decreased from 8.5 to 4.0. In Cohort B, values similarly improved from an average of 72.4 dB to 88.2 dB. HQ scores improved from 35.8 to 18.9. Numeric Rating Scale scores fell from 10.0 to 3.7. Postoperatively there were no complaints of hearing loss. Sixteen out of 21(76%) reported improved quality of life and diminished symptoms of hyperacusis.

CONCLUSION

It is possible that patients suffering from hyperacusis may have a mechanical cause for their symptoms. Further research is necessary to clarify stapes mobility in patients with these symptoms. Excess temporalis tissue reinforcement of the stapes along with round window reinforcement shows promise as a minimally invasive surgical option for patients suffering from hyperacusis.

Multiphoton imaging for morphometry of the sandwich-beam structure of the human stapedial annular ligament

BACKGROUND

The annular ligament of the human stapes constitutes a compliant connection between the stapes footplate and the peripheral cochlear wall at the oval window. The cross section of the human annular ligament is characterized by a three-layered structure, which resembles a sandwich-shaped composite structure. As accurate and precise descriptions of the middle-ear behavior are constrained by lack of information on the complex geometry of the annular ligament, this study aims to obtain comprehensive geometrical data of the annular ligament via multiphoton imaging.

METHODS

The region of interest containing the stapes and annular ligament was harvested from a fresh-frozen human temporal bone of a 46-years old female. Multiphoton imaging of the unstained sample was performed by detecting the second-harmonic generation of collagen and the autofluorescence of elastin, which are constituents of the annular ligament. The multiphoton scans were conducted on the middle-ear side and cochlear side of the annular ligament to obtain accurate images of the face layers on both sides. The face layers of the annular ligament were manually segmented on both multiphoton scans, and then registered to high-resolution μCT images.

RESULTS

Multiphoton scans of the annular ligament revealed 1) relatively large thickness of the core layer compared to the face layers, 2) asymmetric geometry of the face layers between the middle-ear side and cochlear side, and variation of their thickness and width along the footplate boundary, 3) divergent relative alignment of the two face layers, and 4) different fiber composition of the face layers along the boundary with a collagen-reinforcement near the anterior pole on the middle-ear side.

CONCLUSION AND OUTLOOK

Multiphoton microscopy is a feasible approach to obtain the detailed three-dimensional features of the human stapedial annular ligament along its full boundary. The detailed description of the sandwich-shaped structures of the annular ligament is expected to contribute to modeling of the human middle ear for precise simulation of middle-ear behavior. Further, established methodology in this study may be applicable to imaging of other middle-ear structures.

Dexamethasone and Dexamethasone Phosphate Entry into Perilymph Compared for Middle Ear Applications in Guinea Pigs

Dexamethasone phosphate is widely used for intratympanic therapy in humans. We assessed the pharmacokinetics of dexamethasone entry into perilymph when administered as a dexamethasone phosphate solution or as a micronized dexamethasone suspension, with and without inclusion of poloxamer gel in the medium. After a 1-h application to guinea pigs, 10 independent samples of perilymph were collected from the lateral semicircular canal of each animal, allowing entry at the round window and stapes to be independently assessed. Both forms of dexamethasone entered the perilymph predominantly at the round window (73%), with a lower proportion entering at the stapes (22%). When normalized by applied concentration, dexamethasone phosphate was found to enter perilymph far more slowly than dexamethasone, in accordance with its calculated lipid solubility and polar surface area properties. Dexamethasone phosphate therefore has a problematic combination of kinetic properties when used for local therapy of the ear. It is relatively impermeable and enters perilymph only slowly from the middle ear. It is then metabolized in the ear to dexamethasone, which is more permeable through tissue boundaries and is rapidly lost from perilymph. Understanding the influence of molecular properties on the distribution of drugs in perilymph provides a new level of understanding which may help optimize drug therapies of the ear.

Ossicular chain mobilisation versus reconstruction in surgery for isolated malleus and/or incus fixation: systematic review and meta-analysis

OBJECTIVE

To compare post-operative audiometric outcomes for the two prevailing surgical approaches for isolated malleus and/or incus fixation: ossicular mobilisation with preservation of the ossicular chain, and disruption and reconstruction of the ossicular chain.

METHODS

A search was conducted, in December 2016, of PubMed, Scopus, and Cumulative Index to Nursing and Allied Health Literature articles written in English. Papers presenting original data regarding post-operative audiometric outcomes in patients who underwent surgical treatment for malleus and/or incus fixation with a mobile and intact stapes were included. A risk of bias assessment was performed on the 14 selected papers and a tier system was developed. Meta-analysis was accomplished by comparing pooled rates of surgical success by chi-square test and calculating odds ratios by logistical regression. Analysis was performed using Revman5 and R software.Results and conclusionAnalysis of the literature revealed no differences in audiometric outcomes between ossicular chain mobilisation and ossicular chain reconstruction in patients with isolated malleus and/or incus fixation. A large, prospective study comparing both short- and long-term hearing results for ossicular chain mobilisation and ossicular chain reconstruction in this population may identify whether a difference in outcomes exists between the two approaches.

Classification of facial nerve aberration in congenital malformation of middle ear: Implications for surgery of hearing restoration

Objectives

Facial nerve aberration is the most troublesome situation in congenital malformations of middle ear. The aim of our study is to investigate its imaging and clinical features as well as relevant choice of surgical techniques for hearing improvement.

Methods

A retrospective study involving review of clinical data of 227 patients (256 ears) with congenital middle ear anomaly was undertaken, including preoperative computed tomography (CT) data, surgical records and videos.

Results

Aberration involving intratemporal facial nerve was found in 82/256 ears (32.03%) with congenital middle ear anomaly. The most common forms of aberration included overhanging over the oval window (50/82 ears, 60.98%), bifurcation (3/82 ears, 3.66%) and transverse over the promontory (3/82 ears, 3.66%), counting for 68.29% (56/82) of the cases with facial nerve aberration. Concomitant stapes malformation was found in 76/82 ears (92.68%) and atresia or stenosis of the oval window in 27/82 ears (32.93%). In 9/82 ears (10.98%) both stapes and oval window was absent. Elective surgeries for the purpose of hearing improvement included stapodotomy + piston implantation, labyrinthotomy, labyrinthotomy + total ossicular replacement prosthesis (TORP) implantation and Vibrant Soundbridge (VSB) implantation.

Conclusion

The majority of facial nerve aberration in congenital malformation of middle ear involves displacement of facial nerve, in addition to concomitant malformations of the stapes and/or oval window, which may influence the choice of surgery for hearing improvement. VSB implantation may be considered as a useful option.

History of Otosclerosis and Stapes Surgery

The current advancements in otosclerosis therapy cannot be fully appreciated without studying the history, rediscovery, and modification of a once-forgotten procedure. The evolution of stapes surgery can be best summarized into 4 noteworthy eras: the preantibiotic era (which was forgotten and then rediscovered), the fenestration era (mainstreamed by Julius Lempert), the mobilization era (led by Samuel Rosen), and the modern stapedectomy era (revived and revolutionized by John Shea). Each era is unique with its own challenges and ingenious techniques to overcome what used to be among the leading causes of deafness.

Tympanometry and isolated fracture of the stapes

INTRODUCTION

Temporal bone fractures are frequently associated with ossicular dislocations or fractures, most commonly involving the incus. To our knowledge, isolated fracture of the posterior crus of the stapes has not been previously reported.

CASE REPORT

A 20-year-old man consulted for persistent left hypoacusis several months after a head injury. Initial computed tomography of the temporal bone showed a simple temporal bone fracture with no other associated abnormalities. The diagnosis of stapes fracture was suggested by increased compliance on tympanometry, leading to a second thin-section temporal bone computed tomography, which suggested a fracture of the posterior crus of the stapes. Endaural surgical exploration confirmed the diagnosis and allowed placement of ionomer cement in the posterior crus.

DISCUSSION

The possibility of ossicular dislocation or fracture must be considered in patients with persistent conductive hearing loss associated with increased compliance on tympanometry, even when computed tomography of the temporal bone does not show dislocation of the ossicular chain or ossicular fracture. Hearing rehabilitation can be performed by hearing aid or surgical reconstruction of the ossicles.

Gentamicin Applied to the Oval Window Suppresses Vestibular Function in Guinea Pigs

Intratympanic gentamicin therapy is widely used clinically to treat the debilitating symptoms of Ménière's disease. Cochleotoxicity is an undesirable potential side effect of the treatment and the risk of hearing loss increases proportionately with gentamicin concentration in the cochlea. It has recently been shown that gentamicin is readily absorbed through the oval window in guinea pigs. The present study uses quantitative functional measures of vestibular and cochlea function to investigate the efficacy of treating the vestibule by applying a small volume of gentamicin onto the stapes footplate in guinea pigs. Vestibular and cochlea function were assessed by recording short latency vestibular evoked potentials in response to linear head acceleration and changes in hearing threshold, respectively, 1 and 2 weeks following treatment. Histopathology was analyzed in the crista ampullaris of the posterior semi-circular canal and utricular macula in the vestibule, and in the basal and second turns of the cochlea. In animals receiving gentamicin on the stapes footplate, vestibular responses were significantly suppressed by 72.7 % 2 weeks after treatment with no significant loss of hearing. This suggests that the vestibule can be treated directly by applying gentamicin onto the stapes footplate.

Perilymph pharmacokinetics of locally-applied gentamicin in the guinea pig

Intratympanic gentamicin therapy is widely used clinically to suppress the vestibular symptoms of Meniere's disease. Dosing in humans was empirically established and we still know remarkably little about where gentamicin enters the inner ear, where it reaches in the inner ear and what time course it follows after local applications. In this study, gentamicin was applied to the round window niche as a 20 μL bolus of 40 mg/ml solution. Ten 2 μL samples of perilymph were collected sequentially from the lateral semi-circular canal (LSCC) at times from 1 to 4 h after application. Gentamicin concentration was typically highest in samples originating from the vestibule and was lower in samples originating from scala tympani. To interpret these results, perilymph elimination kinetics for gentamicin was quantified by loading the entire perilymph space by injection at the LSCC with a 500 μg/ml gentamicin solution followed by sequential perilymph sampling from the LSCC after different delay times. This allowed concentration decline in perilymph to be followed with time. Gentamicin was retained well in scala vestibuli and the vestibule but declined rapidly at the base of scala tympani, dominated by interactions of perilymph with CSF, as reported for other substances. Quantitative analysis, taking into account perilymph kinetics for gentamicin, showed that more gentamicin entered at the round window membrane (57%) than at the stapes (35%) but the lower concentrations found in scala tympani were due to greater losses there. The gentamicin levels found in perilymph of the vestibule, which are higher than would be expected from round window entry alone, undoubtedly contribute to the vestibulotoxic effects of the drug. Furthermore, calculations of gentamicin distribution following targeted applications to the RW or stapes are more consistent with cochleotoxicity depending on the gentamicin concentration in scala vestibuli rather than that in scala tympani.

Morphological and Morphometrical Study of the Human Ossicular Chain: A Review of the Literature and a Meta-Analysis of Experience Over 50 Years

The ossicular chain has been known for 500 years and yet there are a small number of morphometrical studies. We reviewed the whole literature that is available online regarding the human ossicular chain from an anatomist perspective and correlated the data from all the papers that showed any relevance. Inclusion and exclusion criteria were developed a priori. A thorough description of all ossicular differences has been made and we present their variations in dimensions trying to associate measurements obtained with race. This research included papers spreading on a horizon of over 50 years of worldwide experience. Statistical analysis revealed that there is a great difference in measurements and the results cannot be sufficiently associated. The explanation of this variation in the measurements obtained might be due to errors in the procedure. We conclude that ossicular chain reveals a great variety, and propose that a measurement protocol for auditory ossicles must be widely performed.

[Stapes surgery for otosclerosis using a new titanium prosthesis with a superelastic nitinol clip: First experiences]

BACKGROUND

Coupling of the prosthesis to the long process of the incus is a critical step in stapes surgery. We report first experiences with the NiTiFLEX® stapes prosthesis, a further development of the Soft CliP® stapes prosthesis (Kurz, Dusslingen, Germany). Instead of pure titanium, the CliP® now consists of nitinol, a superelastic nickel-titanium alloy. This further reduces the pressure exerted on the long process of the incus, aiming to improve coupling and minimize the risk of incus luxation.

METHODS

In a monocentric, retrospective cohort study, we evaluated air-bone gap reduction (4PTA0.5-4 kHz), understanding of monosyllables at 65 and 80 dB SPL stimulation levels, and adverse effects, such as changes in bone conduction (4PTA0.5-4 kHz). During a 12-month period (May 2014 to April 2015), stapes surgery was performed in 21 otosclerosis patients using the NiTiFLEX® prosthesis. The footplate was perforated using a CO2 laser (scanning mode; 0.7 mm; 20-21 W) in almost all cases. The diameter of the titan piston was 0.4 mm. Immersion at an angle of almost 90° thus results in a gap between the footplate perforation and the piston of 0.15 mm. Positioning onto the long incus process was performed with a 90°microhook (0.6 mm).

RESULTS

In all cases the NiTiFLEX® stapes prosthesis was inserted without complications. The mean bone conduction threshold did not change significantly postoperatively and the mean air-bone gap (4PTA0.5-4 kHz) improved on average from 29.0 to 9.5 dB HL. Handling of the prosthesis was rated as very good.

CONCLUSION

The limited experience of this study suggests that the NiTiFLEX® stapes prosthesis is a successful further development of the Soft CliP® technique with very good intraoperative handling qualities. While long-term results from larger studies are needed, this case series demonstrates that the hearing outcome is comparable to other prostheses.

Comparative anatomy of the middle ear ossicles of extant hominids--Introducing a geometric morphometric protocol

The presence of three interconnected auditory ossicles in the middle ear is a defining characteristic of mammals, and aspects of ossicle morphology are related to hearing sensitivity. However, analysis and comparison of ossicles are complicated by their minute size and complex three-dimensional shapes. Here we introduce a geometric morphometric measurement protocol for 3D shape analysis based on landmarks and semilandmarks obtained from μCT images and apply it to ossicles of extant hominids (great apes and humans). We show that the protocol is reliable and reproducible over a range of voxel resolutions, and captures even subtle shape differences. Using this approach it is possible to distinguish the hominid taxa by mean shapes of their malleus and incus (p < 0.01). The stapes appears less diagnostic, although this may in part be related to the small sample size available. Using ancestral state estimation, we show that, within hominids, Homo sapiens is derived with respect to its malleus (short manubrium, long corpus, head anterior-posterior flattened, articular facet shape), incus (wide intercrural curvature, long incudal processes, articular facet shape) and stapes (high stapes with kidney-shaped footplate). H. sapiens also shows a number of plesiomorphic shape traits whereas Gorilla and Pan possess a number of autapomorphic characteristics. The Pongo ossicles appear to be close to the plesiomorphic hominid condition. The malleus shows little difference in size among hominids, and allometry is thus of little importance. In contrast, the incus and stapes are more variable in size, and their shape is more strongly related to size differences. Although the form-function relationships in the middle ear are not fully understood, some aspects of ossicle morphology suggest that interspecific differences in hearing capacities are present among hominids. Finally, the results of this study provide a comparative framework for morphometric studies analyzing ossicles of extinct hominids, with a bearing on taxonomy, phylogeny and auditory function.

Congenital anomalies of the incudostapedial joint

OBJECTIVE

To describe congenital anomalies of the incudostapedial joint (ISJ) and to discuss the possible unique embryogenesis of the ISJ based on the two anomalies that were encountered.

SETTING

Tertiary care medical center.

SUBJECTS AND METHODS

Retrospective review of the medical records of all patients with ISJ anomalies.

RESULTS

Four patients presented with congenital hearing loss. Upon further workup, we observed a preserved incudostapedial joint (ISJ) with deficiencies of the incus and stapes in three cases. Our fourth case demonstrated the inverse pattern of the congenital anomalies in which the ISJ was missing with an intact proximal incus and stapes crura. Three patients opted for surgical intervention with improvement in hearing. One case preferred hearing amplification over surgery.

CONCLUSION

Isolated ISJ malformations are uncommon potential causes of congenital conductive hearing loss. Although numerous patterns of ossicular anomalies have been reported in the literature, our case series is the first to demonstrate both the absence of the ISJ in one patient and the presence of the ISJ in the presence of missing stapes crura and incus body in other patients. Though limited by the small number of cases, the inverse relationship of the single case compared to the three other cases, suggests a possible independent embryological development pathway for the ISJ. Therefore, an embryological explanation of the defects should be considered. Additionally, surgical intervention can improve hearing outcomes for patients with isolated ISJ anomalies.

Obliquity of the stapes in otosclerosis: intra-operative observations and implications in stapes surgery

OBJECTIVE

To establish the prevalence of stapes obliquity as observed in otosclerosis patients during stapes surgery by a simple method of intra-operative measurement.

DESIGN

Prospective observational study.

RESULTS

Intra-operative measurements showed that the mean distance (± standard deviation) between the horizontal segment of the facial nerve and stapes crura in 10 cases of otosclerosis was 0.74 mm (± 0.21 mm), whereas in 10 cases of non-otosclerosis the same distance was 0.20 mm (± 0.00). There was no gap (0 mm) between the stapes crura and inferior border of the oval window niche in otosclerotic ears, whereas in non-otosclerotic ears the same distance was 0.13 mm (± 0.05 mm). The differences were statistically significant (p < 0.0001).

CONCLUSION

Obliquity and downward displacement of the stapes occurs in otosclerosis. It has diagnostic value as a new clinical sign in otosclerosis. The findings correlate with late complications and failures in stapes surgery. Methods to avoid these have been suggested.

Parameters for novel incus replacement prostheses

Prostheses replacing the incus in its normal position and equipped with two joints might transfer sound as effectively as the intact ossicular chain and allow adjustment to quasi-static pressure changes. A prerequisite for prostheses development is the access to dimensions and distances of the ossicular chain which are necessary to conceptualize shape and size. Fifteen cadaveric human temporal bone specimens were investigated by means of micro-CT followed by 3D analysis. Each specimen was scanned three times: after removal of incus, after additional removal of the malleus head, and after approaching the umbo to the promontory. Artificial umbo medialization as a surrogate for quasi-static pressure changes leads to relevant variations in the distance between the upper part of the malleus and the stapes. Prostheses replacing the incus in its normal position should be equipped with a sliding ball joint or similar construction to allow adjustment to quasi-static pressure changes.

Development and Integration of the Ear

The perception of our environment via sensory organs plays a crucial role in survival and evolution. Hearing, one of our most developed senses, depends on the proper function of the auditory system and plays a key role in social communication, integration, and learning ability. The ear is a composite structure, comprised of the external, middle, and inner ear. During development, the ear is formed from the integration of a number of tissues of different embryonic origin, which initiate in distinct areas of the embryo at different time points. Functional connections between the components of the hearing apparatus have to be established and maintained during development and adulthood to allow proper sound submission from the outer to the middle and inner ear. This highly organized and intimate connectivity depends on intricate spatiotemporal signaling between the various tissues that give rise to the structures of the ear. Any alterations in this chain of events can lead to the loss of integration, which can subsequently lead to conductive hearing loss, in case of outer and middle ear defects or sensorineural hearing loss, if inner ear structures are defective. This chapter aims to review the current knowledge concerning the development of the three ear compartments as well as mechanisms and signaling pathways that have been implicated in the coordination and integration process of the ear.

Biomechanical strength of glass ionomer cement in incudostapedial rebridging

OBJECTIVE

To study the biomechanical properties of glass ionomer cement used for incudostapedial rebridging.

METHODS

Two groups were established based on the size of the gap between the incus and stapes (1.0 mm in group 1 and 2.0 mm in group 2). Glass ionomer cement was applied to the gaps, and compression tests were performed. Maximum force was measured at the fracture point, and was divided by the cross-sectional area to obtain the maximum compressive strength.

RESULTS

No significant difference was found in the maximum force for the two groups (p = 0.312). The glass ionomer cement diameter was significantly higher in group 2 than in group 1 (p = 0.006). The maximum compressive strength was significantly higher in group 1 than in group 2 (p = 0.042).

CONCLUSION

The fragility of bone cement used in this study was 25.5 per cent higher for a 2 mm gap than for a 1 mm gap. We speculate that the use of bone cement may be safer for the repair of smaller incudostapedial defects.

Transverse fracture of the stapes anterior crus caused by the blast pressure from a land mine explosion

Stapes fractures without other ossicle problems are rare and ossicle problems due to explosion pressure are also rare. We describe a very rare case of stapes anterior crural fracture resulting from a land mine explosion. As this case suggests, a close examination of the ossicles is necessary during an exploration tympanotomy.

The effect of stapes fixation on hearing results in tympanosclerosis treated by mobilization

We aimed to investigate the effect of stapes fixation on hearing results in patients who underwent mobilization surgery due to tympanosclerosis (TS). Seventy-nine patients were retrospectively analyzed and divided into two groups. Forty-four (55.7%) patients with mobile stapes were classified as group 1, and 35 (44.3%) patients with fixed stapes were classified as group 2. Improvement of the air-bone gap (ABG) to become less than 20 dB and the pure-tone average (PTA) by at least 10 dB postoperatively were accepted as success criteria. The PTA and ABG levels were significantly improved in both groups. The pre- and post-operative PTAs were 46.57 ± 15.55 and 25.84 ± 15.47 dB, respectively, in group 1 (p = 0.001). The pre- and post-operative PTAs were 55.64 ± 12.69 and 36.20 ± 14.47 dB, respectively, in group 2 (p = 0.001). The pre- and post-operative ABG levels were 35.36 ± 10.53 and 16.91 ± 8.54 dB, respectively, in group 1 (p = 0.001). The pre- and post-operative ABG levels were 41.68 ± 8.78 and 22.20 ± 10.03 dB, respectively, in group 2 (p = 0.001). A gain ≥10-dB in the PTA in groups 1 and 2 was found in 34 (77.2 %) and 23 (65.7%) patients, respectively, and the difference between the groups was not significant (p = 0.684). The post-operative AGB in groups 1 and 2 was less than 20 dB in 32 (72.7%) and 21 (60%) patients, respectively, and the difference between the groups was not significant (p = 0.733). No significant negative effect of stapes fixation on post-operative hearing results in TS was detected. Successful results can be obtained with a mobilization procedure, even if the stapes is fixed.

A case of the vibrant soundbridge stapes coupler in patients with mixed hearing loss

The Vibrant Soundbridge (VSB) with stapes clip coupler placement at the stapes head has been used successfully to treat mixed hearing loss. Coupling between the floating mass transducer of the VSB and the stapes head is technically less demanding than incus vibroplasty and is more likely to generate a positive outcome without significantly changing residual hearing or resulting in medical or surgical complications. A 65-year-old man with bilateral mixed hearing loss and chronic otitis media underwent vibroplasty with a stapes clip coupler. Speech discrimination scores in both quiet and noise environments showed better functional gain with the VSB than with the use of a conventional hearing aid. The results of the present case show the feasibility of implanting a VSB with a stapes coupler in patients with mixed hearing loss due to chronic otitis media.

The Correlation Between Pre and Postoperative Hearing Level with High Resolution Computed Tomography (HRCT) Findings in Congenital Canal Atresia (CAA) Patients

In managing patient with congenital congenital aural atresia (CAA), preoperative high resolution computed tomography (HRCT) scan and hearing assessment are important. A grading system based on HRCT findings was first introduced by Jahrsdoefer in order to select appropriate candidates for operation and to predict the postoperative hearing outcome in CAA patients. The score of eight and more was considered as a good prognostic factor for hearing reconstruction surgery. However previously in our center this score was not used as the criteria for surgical procedure. This study was conducted at Center A to evaluate the correlation between pre and postoperative hearing level with HRCT based on a Jahrsdoefer grading system in patients with CAA. All records and HRCT films with CAA from January 1997 until December 2007 at Center A were evaluated. The demographic data, operative records, pre and post operative hearing levels and HRCT findings were analyzed. Hearing level in this study was based on a pure tone average of air-bone gap at 500 Hz, 1 kHz and 2 kHz or hearing level obtained from auditory brainstem response eudiometry. This study was approved by Research Ethics Committee (code number, FF-197-2008). Thirty-two ears were retrospectively evaluated. The postoperative hearing level of 30 dB and less was considered as successful hearing result postoperatively. Of the six ears which underwent canalplasty, three had achieved successful hearing result. However, there was no significant correlation between preoperative hearing level (HL) with HRCT score and postoperative HL with HRCT score at 0.05 significant levels (correlation coefficient = -0.292, P = 0.105 and correlation coefficient = -0.127, P = 0.810) respectively. Hearing evaluation and HRCT temporal bone are two independent evaluations for the patients with CAA before going for hearing reconstructive surgery.

The discovery of stapes

Giovanni Filippo Ingrassia revisited and redefined some of Galeno's reports, and was recognized as one of the leading Italian Physicians of the 16th century. Ingrassia principally studied the skull, and gave very important contributions to otorhinolaryngology, including the discovery of the stapes. He also isolated the inferior nasal concha from the maxillary bone, described the frontal sinus, the pterygopalatine fossa and several foramina of the skull. Ingrassia firstly attributed a sensorial function to the middle ear bones, which he called fifth particular function. He also added some details to the description of the VIII cranial nerve, which introduces the concept of bone conducting sound. The most important discovery in Ingrassia's study about the hearing organ was the first description of the third bone of the ossicular chain that he called "stapes". Ingrassia should thus be reconsidered under a new light for his important discovery and for his intuitions about the stapes and its role in hearing. It is appropriate for a Sicilian physician to be placed at his rightful place side-by-side with Eustachio and Valsalva in the history of otology.

Middle ear exploration results in suspected otosclerosis cases: are ossicular and footplate area anomalies rare?

INTRODUCTION

Otosclerosis is a disease of bony labyrinth. Structural changes in the labyrinth often cause ossicular fixation, and thus conductive hearing loss. The purpose of this study was to evaluate middle ear exploration findings and frequency of ossicular and footplate area anomalies in patients with suspected otosclerosis referred to Amiralmomenin and Golsar Hospitals in Rasht, Iran.

MATERIALS AND METHODS

In 47 patients undergone middle ear exploration in Amiralmomenin and Golsar hospitals from April 2001 to March 2011, the intraoperative findings, and other data were extracted from the medical records of the patients. The data was analyzed using SPSS 17 software.

RESULTS

Frequency of fixation of stapes, malleus, and incus by age and sex in patients undergoing middle ear exploration showed that stapes had been fixed in 39 patients, malleus in 6 patients, and incus in 21 patients. Analysis of data showed that there was no significant association between sex and age with fixation of any of ossicles (P>0/05). Middle ear anomalies were seen in 16 cases (34.0%). Overhanging of facial nerve in 4 cases, thick stapedial crura in 5 cases, and perilymph gusher in 2 cases were the most frequent anomalies.

CONCLUSION

This study show that the results of middle ear explorations in our patients in the north of Iran is somehow different from the typical otosclerotic cases, although the frequency of ossicular anomalies is better to be evaluated and compared in different areas of Iran, and other countries.