Modeling, Design, and Evaluation of a Parallel Robot for Cochlear Implant Surgery

A cochlear implant (CI) is a hearing device introduced in the 1980s for profoundly deaf subjects who gained little or no benefit from powerful hearing aids. This device comprises an electrode array inserted in the cochlea, connected to an internal receiver, and an externally worn speech processor. The CI transforms acoustic signals into electrical currents which directly stimulate the auditory nerve. Since the early 1990s, cochlear implantation in children has been developing rapidly. Although it is still difficult to predict how a child will perform with a cochlear implant, the success of cochlear implantation can no longer be denied. In this paper, some recent papers and reports, and the results of the various Nijmegen cochlear implant studies, are reviewed. Issues about selection, examinations, surgery and the outcome are discussed. Overall, our results were comparable with those of other authors. It can be concluded that cochlear implantation is an effective treatment for postlingually deaf as well as prelingually (congenital or acquired) deaf children with profound bilateral sensorineural deafness.

Objective(s):Robotic-assisted electrode array (EA) insertion is a promising technique that may enhance hearing preservation in cochlear implant (CI) surgery. The purpose of our study is to understand the extent to which robotic-assisted EA insertion improves hearing preservation.Methods:Twenty-four adult patients underwent CI surgery with manual EA insertion and 27 adult patients underwent CI surgery with robotic-assisted EA insertion using the iotaSOFT system. The EAs used included the Flex 20/24/26. The primary outcome variable was low frequency pure-tone average (LFPTA), defined as mean audiometric threshold at 125, 250, and 500 Hz. This was measured preoperatively, at initial activation (within 4 weeks of surgery), and subsequently at 2 weeks, 3 months, 6 months, and 1 year. Functional acoustic hearing was defined as LFPTA < 80 dB HL.Results:Seventeen out of 24 patients (71%) in the manual insertion group and 23 out of 27 patients (85%) in the robotic-assisted EA insertion group had preserved functional acoustic hearing (< 80 dB HL) up till 1 year (Fisher’s exact test (two-tailed) is not statistically significant, p = 0.31). The number needed to treat with robotic-assisted EA insertion to prevent one additional negative outcome of loss of functional acoustic hearing would be 7 (1/0.14).Conclusion:Robotic-assisted EA insertion is associated with improved hearing preservation over 1 year compared with manual insertion. Hearing preservation leads to improved outcomes and therefore every effort should be made to preserve the delicate structure and function of the cochlea during EA insertion. Robotic-assisted EA insertion advances that objective.Level of Evidence:III (cohort study).

To describe a method of cochlear implantation in which the opening of the cochlea and the electrode array insertion are performed under water (underwater technique). Retrospective patient review. Academic tertiary referral center. Fifteen implantations in children and adult patients with residual hearing at the frequencies 250, 500, and 1000 Hz on the unaided preoperative pure-tone audiometry were included in this study. Cochlear implantation with a conventional full-length electrode, in which the opening of the cochlea and the electrode array insertion are performed after the tympanic cavity was filled with body-temperature Ringer solution. Changes on residual hearing 6 to 8 weeks after surgery and at subsequent follow-up appointments were analyzed. Preservation of residual hearing was defined as measurable postoperative threshold at the frequencies 250, 500, and 1000 Hz. Overall postimplant hearing preservation 6 to 8 weeks after implantation was achieved in 13 of the patients (87%). Subsequent follow-up was performed on average 15.2 months after surgery (range, 7-32) in 14 out of 15 patients. At this late postoperative evaluation preservation of hearing was recorded in nine patients (64%), whereas in the remaining five patients (36%) no residual hearing was measured. The underwater technique offers a reliable nontraumatic method for electrode array insertions during cochlear implantation. The method respects the physiology of the cochlea und minimizes the pressure variations during cochlear opening and implantation.

IntroductionElectrocochleography (ECochG) is increasingly used in cochlear implant (CI) surgery, in order to monitor the effect of insertion of the electrode array aiming to preserve residual hearing. However, obtained results are often difficult to interpret. Here we aim to relate changes in ECochG responses to acute trauma induced by different stages of cochlear implantation by performing ECochG at multiple time points during the procedure in normal-hearing guinea pigs.Materials and methodsEleven normal-hearing guinea pigs received a gold-ball electrode that was fixed in the round-window niche. ECochG recordings were performed during the four steps of cochlear implantation using the gold-ball electrode: (1) Bullostomy to expose the round window, (2) hand-drilling of 0.5–0.6 mm cochleostomy in the basal turn near the round window, (3) insertion of a short flexible electrode array, and (4) withdrawal of electrode array. Acoustical stimuli were tones varying in frequency (0.25–16 kHz) and sound level. The ECochG signal was primarily analyzed in terms of threshold, amplitude, and latency of the compound action potential (CAP). Midmodiolar sections of the implanted cochleas were analyzed in terms of trauma to hair cells, modiolar wall, osseous spiral lamina (OSL) and lateral wall.ResultsAnimals were assigned to cochlear trauma categories: minimal (n = 3), moderate (n = 5), or severe (n = 3). After cochleostomy and array insertion, CAP threshold shifts increased with trauma severity. At each stage a threshold shift at high frequencies (4–16 kHz) was accompanied with a threshold shift at low frequencies (0.25–2 kHz) that was 10–20 dB smaller. Withdrawal of the array led to a further worsening of responses, which probably indicates that insertion and removal trauma affected the responses rather than the mere presence of the array. In two instances, CAP threshold shifts were considerably larger than threshold shifts of cochlear microphonics, which could be explained by neural damage due to OSL fracture. A change in amplitudes at high sound levels was strongly correlated with threshold shifts, which is relevant for clinical ECochG performed at one sound level.ConclusionBasal trauma caused by cochleostomy and/or array insertion should be minimized in order to preserve the low-frequency residual hearing of CI recipients.

Recent advancements toward minimizing surgical trauma and preserving residual hearing during cochlear implantation have promoted the use of intracochlear electrocochleography (ECochG) for intraoperative surveillance. However, variations in the distribution of response generators throughout the cochlea complicate the interpretation of signal changes during electrode array insertion. This exploratory study aimed to investigate whether simultaneous recordings from 2 locations within the cochlea could address this issue. This was done by (1) comparing recordings acquired simultaneously from an apical and a more basal electrode contact during atraumatic electrode array insertions; and (2) comparing these response patterns with preoperative pure-tone audiograms. In 10 standard CI recipients, ECochG recordings were obtained during stepwise insertion of a short-temporary electrode array. Simultaneous intracochlear recordings were acquired from 2 contacts separated by 4.2mm in response to 500Hz tone bursts. For both electrode contacts, the differences between responses to alternating-polarity stimuli, hereafter named "ECochG responses," were derived. After completion of the recordings, the temporary electrode array was removed and a standard CI electrode array inserted. In 6 of 10 participants, ECochG response amplitude decreases of ≥3dB were recorded at the more basal electrode contact. In 4 cases, these amplitude drops were preceded by amplitude drops recorded at the apical electrode contact, with both occurring no more than 1.7mm apart along the cochlear duct. Trauma would be expected to produce a simultaneous amplitude drop-at different recording locations-for both electrodes. In contrast, a drop at the basal electrode that is preceded by a drop in the ECochG recording at the apical electrode, with both drops occurring at approximately the same location, is likely atraumatic. These atraumatic drops may also be associated with large phase shifts. Overall, the ECochG response tracks recorded at the apical and more basal contact were similar, while the ECochG response patterns and audiogram did not show a strong resemblance. The proposed approach could facilitate the detection of ECochG response changes relevant for predicting hearing preservation during cochlear implantation. By distinguishing between simultaneous and sequential amplitude drops, this method could provide additional insights into the atraumatic nature of certain ECochG response changes.

Conclusions: The straight electrode array with length of 31 mm can be fully inserted using round window insertion in cochlear implantation with Mondini’s deformity. It is a safe and effective process, but also a challenging task of the full implantation in children with Mondini’s deformity.Objective: The aim of this study is to discuss whether the straight electrode array with a length of 31 mm could be fully inserted in cochlear implantation with Mondini’s deformity.Methods: A chart review of 30 patients undergoing cochlear implantation with Mondini’s deformity using the electrode array with length of 31 mm was undertaken from January 2012 and December 2015 in Anhui Provincial Hospital.Results: Full insertion of the straight electrode array with length of 31 mm were performed successfully in all patients with Mondini’s deformity using round window insertion. Resistance was not encountered while introducing the electrodes. Ten of 30 patients had cerebrospinal fluid drainage during cochlear implantation. Cerebrospinal fluid drainage was controlled with small pieces of temporalis fascia packing round window in all patients. Intra-operative neural response telemetry was performed in all patients, and results were good. The result of X-ray showed proper placement of the cochlear implant electrode array. During surgery, no patients had experienced any immediate or delayed post-operative complications such as wound infection, intracranial complication, extrusion, or migration of the implant during an average follow-up period of 6–36 months.

Surgical complication related to an electrode array in cochlear implantation is rare; however, in cases with cochlear ossification after bacterial meningitis, the electrode array insertion can be problematic. The patient complained of an aggravated hearing impairment after bacterial meningitis. He was performed cochlear implantation. Both intraoperative neural response telemetry (NRT) and impedance telemetry results were normal. However, postoperative transorbital x-ray revealed only partial insertion of the electrode array. Four days after the surgery, he complained dizziness. Postoperative temporal bone CT showed malposition of the electrode array into the vestibule. Revision surgery was performed and a new electrode array was fully inserted after further drilling out into the cochleostomy window. Though intraoperative NRT and impedance telemetry are normal, misdirection of an electrode array can occur. Therefore, it should be considered that intraoperative radiologic examination is used after insertion of an electrode array for assessment of an electrode array location. (J Clinical Otolaryngol 2011;22:86–89)

The round window insertion (RWI) and cochleostomy approaches are the 2 most common surgical techniques used in cochlear implantation (CI). However, there is no consensus on which approach is ideal for electrode array insertion, in part because visualization of intracochlear electrode position is challenging, so postoperative assessment of intracochlear electrode contact is lacking. To measure and compare electrode array position between RWI and cochleostomy approaches for CI insertion. Retrospective case-comparison study of 17 CI users with Med-El standard-length electrode arrays who underwent flat-panel computed tomography scans after CI surgery at a tertiary referral center. The data was analyzed in October 2015. Flat-panel computed tomography scans were collected between January 1 and August 31, 2013, for 22 electrode arrays. The surgical technique was identified by a combination of operative notes and imaging. Eight cochleae underwent RWI and 14 cochleae underwent cochleostomy approaches anterior and inferior to the round window. Interscalar electrode position and electrode centroid distance to the osseous spiral lamina, lateral bony wall, and central axis of the modiolus. Nine participants were men, and 8, women; the mean age was 54.4 (range, 21-64) years. Electrode position was significantly closer to cochlear neural elements with RWI than cochleostomy approaches. Between the 2 surgical approaches, the RWI technique produced shorter distances between the electrode and the modiolus (mean difference, -0.33 [95% CI, -0.29 to -0.39] mm in the apical electrode; -1.42 [95% CI, -1.24 to -1.57] mm in the basal electrode). This difference, which was most prominent in the first third and latter third of the basal turn, decreased after the basal turn. The RWI approach was associated with an increased likelihood of perimodiolar placement. Opting to use RWI over cochleostomy approaches in CI candidates may position electrodes closer to cochlear neural substrates and minimize current spread. These findings need to be interpreted in light of the increased potential for osseous spiral lamina trauma with reduced distances between the electrode array and modiolus.

Abstract. In Russia, more than 40 medical devices with artificial intelligence (AI) are registered in various healthcare fields, and tens of thousands of technologies worldwide utilize AI in medicine. In the US alone, the FDA has approved over 1,000 medical devices with AI and machine learning. No AI-enabled medical devices have yet been registered in Russia in the field of otolaryngology. In other countries, prototypes and registered devices already exist in otolaryngology and cochlear implantation. These devices allow for predicting the effectiveness of cochlear implantation or the possibility of preserving residual hearing, including in cases of inner ear malformations. AI is used for preoperative diagnostics and helps stratify risks. Rapid development of AI systems is occurring in CT and MRI image analysis. Robot-assisted AI-controlled technologies provide high surgical precision and controlled insertion of electrode arrays, resulting in less trauma to the inner ear than traditional surgery. Intraoperative testing methods combined with real-time AI algorithms allow for the detection of electrode array deviations from the optimal trajectory during insertion into the cochlea. CT and MRI image analysis determines the position of the cochlear implant electrode array, which is used to configure the cochlear implant processors. AI systems can use telemetry to assess electrode position, partially replacing radiographic monitoring. Algorithms for automatically determining the electrically evoked compound action potential (ECAP) have been described during speech processor programming. Research has shown that speech intelligibility is significantly improved by using deep neural network preprocessing of speech in noise. AI-powered self-help apps are used in the rehabilitation of patients with cochlear implants. Modern advances in information technology make it possible to significantly automate and improve the efficiency of one of the most complex areas of otolaryngology—cochlear implantation.

Cochlear implantation, the primary treatment for severe to profound hearing loss, relies critically on proper electrode array design and insertion. This systematic review and meta-analysis examined the complications and hearing outcomes of cochlear implantation in ossified cochleae, compared with non-ossified cases, and explored management strategies to enhance surgical success and patient outcomes. A comprehensive literature search was conducted using the PubMed, Scopus, Web of Science, and Cochrane Library databases, following the PRISMA guidelines. We used the following broad search strategy: Ossified OR ossification and cochlear AND implantation or implant. Two independent investigators screened titles, abstracts, and full texts and extracted data. A total of 20 studies and 971 patients were included. Post implantation and intraoperative complications had pooled incidence rates of 13.48% and 7.2%, respectively. Complete electrode insertion was successful in 82.2% of cases, while partial insertion occurred in 22.6%. Hearing performance outcomes [Speech Perception Categories (SPCs), Categories of Audiological Performance Scores (CAPS), Speech reception threshold (SRT), and Speech Intelligibility Rating (SIR)] were significantly better for patients without ossification (SMD=0.35, P =0.005), although word and sentence scores showed no significant differences. Despite adaptations such as modified drilling and electrode arrays, hearing outcomes were inferior compared with non-ossified cochleae in addition to the risk of complications associated with the procedure. These findings underscore the need for continued research to improve outcomes in this patient population and have important implications for surgical planning and patient counseling.

Speech recognition outcomes with a cochlear implant (CI) are highly variable. One factor suggested to correlate with CI-aided speech recognition is frequency-to-place mismatch, or the discrepancy between the natural tonotopic organization of the cochlea and the electric frequency allocation of the CI electrodes within the patient's cochlea. To evaluate the association between frequency-to-place mismatch and speech recognition outcomes in a large cohort of postlingually deafened adult CI users, while controlling for various clinical factors known to be associated with those outcomes. This retrospective cohort study used data from a CI program at a tertiary medical center and included CIs from postlingually deafened adult CI users. After excluding patients whose data were not logged, patients with implantations occurring between 2016 and 2023 were included in the analysis. The data were extracted in November 2023. Results of the Consonant-Nucleus-Consonant (CNC) monosyllabic word recognition test measured in the CI-aided alone condition 1 month, 3 months, 6 months, and 12 months after activation served as the main outcome. The independent variables included frequency-to-place mismatch, electrode array type, mean modiolar distance, electrode position, age at implantation, biological sex, contralateral hearing abilities, time since CI activation (test interval), and daily device use. In 498 CIs from 447 postlingually deafened adults (mean [SD] age, 63.1 [17.1] years; 271 [54.4%] CIs with male users), frequency-to-place mismatch was negatively correlated with CI-aided speech recognition outcomes, but the association was only significant for precurved electrode arrays and not straight electrode arrays. In the linear mixed effects model for straight electrode arrays, only test interval (β = 1.14 [95% CI, 0.90-1.38]) and daily device use (β = 0.90 [95% CI, 0.42-1.38]) were correlated with the improvement of word recognition over the first year of device use. In the model for precurved electrode arrays, mismatch at 1500 Hz (β = -0.011 [95% CI, -0.011 to -0.006]), scalar location (β = 16.37 [95% CI, 9.01 to 23.74]), test interval (β = 1.18 [95% CI, 1.18-1.41]) and daily device use (β = 1.65 [95% CI, 1.15-2.14]) all were significantly associated with the improvement of word recognition over the first year of device use. In this cohort study of postlingually deafened adult CI users, including both straight and precurved electrode arrays, daily device use and time since CI activation were found to be significantly associated with improved CI-aided speech recognition outcomes. Frequency-to-place mismatch at 1500 Hz and scalar location were associated with word recognition only for precurved arrays. These findings suggest that, for patients with straight arrays, any interference produced by frequency-to-place mismatch may be overcome by adaptation, which could be supported by daily device use. However, for patients with precurved arrays, daily device use may not be sufficient to completely overcome electrode placement factors, including scalar location and mismatch.

Cochlear implantation is currently regarded as a safe and minimally invasive procedure. However, cochlear implantation can have an impact on vestibular function, despite the lack of correlation between patient symptomatology and damage in vestibular tests. Thus, the present study aims to analyze the presence of hydrops and histological reactions at the level of the vestibule after cochlear implantation with dexamethasone pump delivery in Macaca fascicularis (Mf). A detailed histological study was conducted on a total of 11 Mf. All 11 Mf were divided into three groups: 5 Mf were implanted with an electrode array HL-14 connected to a pump delivering FITC-dextran for 24 h (Group A); 4 Mf were implanted with a CI electrode array attached to a pump for FITC-dextran delivery for 7 days (Group B); and 2 Mf were considered the control group, without any kind of cochlear device implantation (Group C). After drug deliver, the selected macaques were euthanized to collect tissue samples for histological analysis. An experienced observer, focusing on the utricle and saccule areas, conducted a blinded inner ear histology analysis. Surgical procedures were successfully performed in all cases. No signs of cochlear reaction to the device were observed, including neither collapse nor fibrosis. Endolymphatic sinus dilatation was observed in Mf4A and Mf3B, while cochlear hydrops was observed in Mf3A. The mean areas of the utricle and saccule exhibited some statistically significant differences, specifically, in the saccule between groups C and both groups A (p = 0.028) and B (p = 0.029); however, no significant differences were observed between groups A and B or among comparisons of the utricle. A significant concern relates to the safety of cochlear implantation with regard to vestibular preservation and hearing. New advancements in electrode arrays, such as CI devices coupled with delivery pumps, pose a challenge in maintaining minimally traumatic surgical concept-based procedures without affecting the inner ear homeostasis. The implantation of this device may cause vestibular hydrops in the saccule, indicating that the longer the time of substance release, the greater the grade of hydrops evidenced at the saccular level. Apart from this finding, the risk of histological damage to the vestibule is low.

The level of hearing rehabilitation enjoyed by cochlear implant (CI) recipients has increased dramatically since the introduction of these devices. This improvement is the result of continual development of these systems and the inclusion of subjects with less severe auditory pathology. Developments include advanced signal processing, higher stimulation rates, greater numbers of channels, and more efficient electrode arrays that are less likely to produce insertion damage. New directions in the application of CIs, particularly in combined acoustic and electrical stimulation, and increasing performance expectations will place greater demands on future electrode arrays. Specifically, the next generation of arrays must be reliably inserted without damage, must maintain residual acoustic function, and may need to be inserted more deeply. In this study, we measured the mechanical properties of eight clinical and prototype human CI electrode arrays and evaluated insertion trauma and insertion depth in 79 implanted cadaver temporal bones. We found that the size and shape of the array directly affect the incidence of observed trauma. Further, arrays with greater stiffness in the plane perpendicular to the plane of the cochlear spiral are less likely to cause severe trauma than arrays with similar vertical and horizontal stiffness.

Cochlear implants provide hearing perception to people with severe to profound hearing loss. The electrode array (EA) inserted during the surgery directly stimulates the hearing nerve, bypassing the acoustic hearing system. The complications during the EA insertion in the inner ear may cause trauma leading to infection, residual hearing loss, and poor speech perception. This work aims to reduce the trauma induced during electrode array insertion process by carefully designing a sensing method, an actuation system, and data-driven control strategy to guide electrode array in scala tympani. Due to limited intra-operative feedback during the insertion process, complex bipolar electrical impedance is used as a sensing element to guide EA in real time. An automated actuation system with three degrees of freedom was used along with a complex impedance meter to record impedance of consecutive electrodes. Prediction of EA direction (medial, middle, and lateral) was carried out by an ensemble of random forest, shallow neural network, and k-nearest neighbour in an offline setting with an accuracy of 86.86%. The trained ensemble was then utilized in vitro for prediction and correction of EA direction in real time in the straight path with an accuracy of 80%. Such a real-time system also has application in other electrode implants and needle and catheter insertion guidance.

HeadLocNet: Deep convolutional neural networks for accurate classification and multi-landmark localization of head CTs.