Validation method of a middle ear mechanical model to develop a surgical simulator.

Ossicular surgery requires a high dexterity for the manipulation of the fragile and small middle ear components. Currently, the only efficient technique for training residents in otological surgery is through the use of temporal bone specimens, where any existing surgical simulator does not provide useful feedback. The objective of this study was to develop a finite-element model of the human ossicular chain dedicated to surgical simulation and to propose a method to evaluate its behavior. A model was developed based on human middle ear micromagnetic resonance imaging. The mechanical parameters were determined according to published data. To assess its performance, the middle ear transfer function was analyzed. The robustness of our model and the influence of different middle ear components were also evaluated at low frequency by static force pressure simulations. The mechanical behavior of our model in nominal and pathological conditions was in good agreement with published human temporal bone measurements. We showed that the cochlea influences the transfer function only at high frequency and could be omitted from a surgical simulator. In addition, surgeons were able to manipulate the validated middle ear model with a real-time haptic feedback. The computational efficiency of our approach allowed real-time interactions, making it suitable for use in a training simulator.

Is electrode-modiolus distance a prognostic factor for hearing performances after cochlear implant surgery?

The aim of this study was to evaluate electrode array position in relation to cochlear anatomy and its influence on hearing performance in cochlear implantees. Twenty-two patients (25 ears) with Med-El cochlear implants were included in this retrospective study. A negative correlation was observed between electrode-modiolus distance (EMD) at the cochlear base and monosyllabic word discrimination 6 months after implantation. We found no correlation between EMD and hearing outcome at 12 months. The insertion depth/cochlear perimeter ratio appeared to negatively influence the EMD at the base. Indeed, deep insertions in small cochleae appeared to yield smaller EMD and better hearing performance. This observation supports the idea of preplanning the surgery by adapting the electrode array to the length of the available scala tympani.

From conception to application of a tele-operated assistance robot for middle ear surgery.

The authors' goal was to design and evaluate a robot dedicated to middle ear surgery. Specifications for dimensions, forces, and kinematics were collected, based on the otosclerosis procedure. The robot structure has a compact geometry with 3 linear and 3 rotatory motors. It is remotely piloted via a robot-surgeon interface under operative microscope. Ability to reach anatomical targets, to perform stapedectomy, and to place prosthesis in a model of stapedotomy was evaluated by 6 surgeons. Multiple anatomical targets in the middle ear could be successfully reached without damaging surrounding structures. The robot could be used under operative microscope with minimal visual field impairment or jointly with a 4-mm endoscope through the external auditory canal to perform stapedectomy in temporal bone specimens. Prosthesis could be inserted in the stapedotomy model. The assistance robot is the first prototype with 6 degrees of freedom, a kinematic structure, and dimensions optimized for tele-operated middle ear surgery.

Classification of Wideband Tympanometry by Deep Transfer Learning With Data Augmentation for Automatic Diagnosis of Otosclerosis.

Otosclerosis is a common disease of the middle ear leading to stapedial fixation. Its rapid and non-invasive diagnosis could be achieved through wideband tympanometry (WBT), but the interpretation of the raw data provided by this tool is complex and time-consuming. Convolutional neural networks (CNN) could potentially be applied to this situation to help the clinicians categorize WBT data. A dataset containing 135 samples from 80 patients with otosclerosis and 55 controls was obtained. We designed a lightweight CNN to categorize samples into the otosclerosis and control. Receiver operating characteristic (ROC) analysis showed an area under the curve (AUC) of 0.95 ±0.011, and the F1-score was 0.89 ±0.031 ( r=10). The performance was further improved by data augmentation schemes and transfer learning strategies (AUC: 0.97 ±0.010, F1-score: 0.94 ±0.016, , ANOVA). Finally, the most relevant diagnostic features employed by the CNN were assessed via the activation pattern heatmaps. These results are crucial for the visual interpretation of WBT graphic outputs which clinicians use in routine, and for a better understanding of the WBT signal in relation to the ossicular mechanics.

Functional results of Vibrant Soundbridge middle ear implants in conductive and mixed hearing losses.

OBJECTIVE: Our purpose was to evaluate the results of Vibrant Soundbridge (VSB) in conductive or mixed hearing loss. MATERIALS AND METHODS: Twenty-five adult patients (29 ears) with a mixed or conductive hearing loss and various etiologies were included in this retrospective study. The preoperative ipsilateral pure tone average was 71 ± 3.0 dB, and the average bone conduction threshold was 42 ± 2.8 dB (n = 29). The transducer was placed on the long apophysis of the incus (n = 16), in the round window (n = 10) or on the stapes (n = 3). RESULTS: No complications were noted. The bone conduction threshold remained unchanged. VSB was activated in all cases. The postoperative pure tone average without VSB was 63 ± 3.9 dB (n = 24) and with VSB in free-field condition 24 ± 2.1 dB (n = 22). CONCLUSIONS: VSB is safe and efficacious for auditory rehabilitation in conductive and mixed hearing losses.

Protective effect of systemic administration of erythropoietin on auditory brain stem response and compound action potential thresholds in an animal model of cochlear implantation.

OBJECTIVES: An animal model of cochlear implantation has been developed, and the hearing threshold was evaluated after different surgical procedures. The effect of perioperative systemic administration of erythropoietin on the hearing loss induced by cochlear implantation was tested. METHODS: Twenty-nine guinea pigs with normal hearing underwent implantation of a 254-microm-diameter array through a cochleostomy. The effects on hearing of cochleostomy and transient and long-term array implantation (21 days) were assessed by testing of the auditory brain stem responses and compound action potentials. Eleven implanted animals received intraperitoneal administration of erythropoietin. Selected computed tomographic scans and cochlear histologic studies were performed 1 month after implantation to confirm proper placement of the array. The erythropoietin concentration at the time of surgery was assessed in samples of perilymph, cerebrospinal fluid, and blood. RESULTS: The cochleostomy and transient array insertion had no effect on hearing thresholds. Long-term array implantation induced a stable decrease of hearing threshold (30 dB), a decrease that was reduced by 12 dB in erythropoietin-treated animals. The erythropoietin-treated animals had better hearing preservation at higher frequencies. Fibrosis surrounding the array was seen in both groups. CONCLUSIONS: The hearing loss observed was probably due to the presence of the array in the cochlea. The intraperitoneal injection of erythropoietin improved the hearing threshold shift induced by implantation.

Minimally invasive computer-assisted approach for cochlear implantation: a human temporal bone study.

Computer-assisted navigation systems can now potentially guide the surgeon to the cochlea with a trajectory avoiding the facial nerve through a keyhole approach. Five temporal bone specimens, with 4 titanium screws placed in the mastoid cortex, were studied. Preoperative computed tomographic scan images were loaded on an electromagnetic computer-assisted surgery (CAS) system (Digipointeur, Collin, Bagneux, France). A drill was connected to the CAS to monitor its progression continuously. A conical approach passing through the facial recess and ending in the scala tympani was performed. A 0.5-mm wire was inserted into the cochlea. The keyhole approach was technically feasible in all cases. No facial nerve injury was observed on imaging and dissection control. The wire was positioned in the scala tympani and the position accuracy of the CAS was <0.76 mm on the target in all cases. The CAS system with fiducial markers yielded sufficient precision to allow a minimally invasive approach to the cochlea.

Augmented reality for inner ear procedures: visualization of the cochlear central axis in microscopic videos.

PURPOSE: Visualization of the cochlea is impossible due to the delicate and intricate ear anatomy. Augmented reality may be used to perform auditory nerve implantation by transmodiolar approach in patients with profound hearing loss. METHODS: We present an augmented reality system for the visualization of the cochlear axis in surgical videos. The system starts with an automatic anatomical landmark detection in preoperative computed tomography images based on deep reinforcement learning. These landmarks are used to register the preoperative geometry with the real-time microscopic video captured inside the auditory canal. Three-dimensional pose of the cochlear axis is determined using the registration projection matrices. In addition, the patient microscope movements are tracked using an image feature-based tracking process. RESULTS: The landmark detection stage yielded an average localization error of [Formula: see text] mm ([Formula: see text]). The target registration error was [Formula: see text] mm for the cochlear apex and [Formula: see text] for the cochlear axis. CONCLUSION: We developed an augmented reality system to visualize the cochlear axis in intraoperative videos. The system yielded millimetric accuracy and remained stable throughout the experimental study despite camera movements throughout the procedure in experimental conditions.

Relation between renin-angiotensin-aldosterone system and otosclerosis: a genetic association and in vitro study.

OBJECTIVE/HYPOTHESIS: Angiotensin II (Ang II) may be implicated in the regulation of bone remodeling, and its activity is related to several gene polymorphisms including AGT M235T for plasmatic and tissular concentrations of angiotensinogen (AGT), ACE I/D for the angiotensin-converting enzyme activity, and AT(1)R A/C(1166) for the Ang II receptor function. The objective of this study was to investigate the implication of this hormone in otosclerosis. STUDY DESIGN: Prospective case-control study. METHODS: The above-mentionedpolymorphisms were investigated in 186 patients with otosclerosis and 526 healthy controls, both groups originated from the French Caucasian population. Primary cell cultures of stapedial bone from patients with otosclerosis (n = 6) and control subjects (n = 5) were investigated for the messenger ribonucleic acid expressions of Ang II receptors (Types 1 and 2) and cellular AGT and the effect of Ang II (10(-7) mol/L, 24 h) on the alkaline phosphatase activity and the interleukin-6 secretion in the culture media. RESULTS: A significant association was found between otosclerosis and the AGT M235T and the ACE I/D polymorphisms. Higher proportions of TT (29% versus 16%; p < 0.01) and DD (50% versus 38%; p < 0.05) genotypes were observed in cases versus controls. No association was found between the AT(1)R A/C(1166) polymorphism and otosclerosis. Ang II receptor Types 1 and 2 and AGT were detected in the cultures. Ang II increased the in vitro secretion of interleukin-6 and decreased the alkaline phosphatase activity only in otosclerotic cells. CONCLUSION: These observations suggest a relation between the local renin angiotensin system activity and otosclerosis, opening new therapeutic insights.

Diode laser in otosclerosis surgery: first clinical results.

OBJECTIVE: To evaluate the functional results of otosclerosis surgery using diode laser. STUDY DESIGN: Retrospective cohort analysis. PATIENTS: One hundred seven patients operated on for otosclerosis with a diode laser (119 ears, all primary cases) and 141 patients operated on with a conventional technique (141 ears, all primary cases). Revision cases using the diode laser were also described. METHODS: Preoperative tomographic computed scan findings and intraoperative observations were collected. Pure-tone and vocal audiometry was performed preoperatively and postoperatively (at 3 mo and 1 yr). RESULTS: In the laser group, the air-bone gap was 29 +/- 0.8 dB (n= 112) preoperatively and 9 +/- 0.6 dB (n = 58) at 1 year. Air conduction was improved by 22 +/- 1.7 dB at 1 year (n = 58). In the conventional group, the air-bone gap was 32 +/- 0.9 dB (n=127) preoperatively and 10 +/- 0.6 dB (n = 127) at 1 year. Air conduction was improved by 25 +/- 1.1 dB (n = 127) at 1 year. No difference of hearing gain was observed between the 2 groups at 1 year. A decreased rate of footplate fracture was observed with the diode laser (3.6%) compared with the conventional technique (21.3%). CONCLUSION: Diode laser is a reliable and safe device for otosclerosis surgery. The functional results were similar to those reported in other series.