Insertion Of Electrode Array Research Articles

Integrated Augmented Reality Feedback for Cochlear Implant Surgery Instruments

In this article, we present a visualization system to provide assistance in cochlear implant surgery which can be seamlessly integrated within the devices that are currently used in surgery. The system is intended to improve tool alignment in positioning and during insertion, with the aim of reducing the problems encountered during perimodiolar electrode array insertion. Our system is composed of a semi-autonomous hand-held surgical tool, coupled with an optical tracker to monitor the tool position and an operating microscope. The microscope live view is overlaid with guidance information in the form of augmented reality to assist the surgeon in positioning the surgical tool and maintain that position during insertion. Our approach shows promising results in tool alignment, which are comparable to the state of the art.

Robot-assisted Cochlear Implant Electrode Array Insertion in Adults: A Comparative Study With Manual Insertion.

To describe the first cochlear array insertions using a robot-assisted technique, with different types of straight or precurved electrode arrays, compared with arrays manually inserted into the cochlea. Retrospective review. Tertiary otologic center. Twenty cochlear implantations in the robot-assisted group and 40 in the manually inserted group. Cochlear implantations using a robot-assisted technique (RobOtol) with straight (eight Cochlear CI522/622, and eight Advanced Bionics Hifocus Slim J) or precurved (four Advanced Bionics Hifocus Mid-Scala) matched to manual cochlear implantations. Three-dimensional reconstruction images of the basilar membrane and the electrode array were obtained from pre- and postimplantation computed tomography. Rate and localization of scalar translocations. For straight electrode arrays, scalar translocations occurred in 19% (3/16) of the robot-assisted group and 31% (10/32) of the manually inserted group. Considering the number of translocated electrodes, this was lower in the robot-assisted group (7%) than in the manually inserted group (16%) (p < 0.0001, χ2 test). For precurved electrode arrays, scalar translocations occurred in 50% (2/4) of the robot-assisted group and 38% (3/8) of the manually inserted group. This study showed a safe and reliable insertion of different electrode array types with a robot-assisted technique, with a less traumatic robotic insertion of straight electrode arrays when compared with manual insertion.

A simple tool to automate the insertion process in cochlear implant surgery

PurposeAutomated insertion of electrode arrays (EA) in cochlear implant surgery is presumed to be less traumatic than manual insertions, but no tool is widely available in the operating room. We sought (1) to design and create a simple tool able to automate the EA insertion process; and (2) to perform preliminary evaluations of the designed prototype.MethodsA first prototype of a tool with maximum simplicity was designed and fabricated to take advantage of hydraulic actuation. The prototype facilitates automated forward motion using a syringe connected to an infusion pump. Initial prototype evaluation included: (1) testing of forward motion at different velocities (2) EA insertion trials into an artificial cochlear model with force recordings, and (3) evaluation of device handling, fixation and positioning using cadaver head specimens and a surgical retractor. Alignment of the tool was explored with CT imaging.ResultsIn this initial phase, the prototype demonstrated easy assembly and ability to respond to hydraulic actuation driven by an infusion pump at different velocities. EA insertions at an ultra-slow velocity of 0.03 mm/s revealed smooth force profiles with mean maximum force of 0.060 N ± 0.007 N. Device positioning with an appropriate insertion axis into the cochlea was deemed feasible and easy to achieve.ConclusionsInitial testing of our hydraulic insertion tool did not reveal any serious complications that contradict the initially defined design specifications. Further meticulous testing is needed to determine the safety of the device, its reliability and clinical applicability.

Simultaneous Intra- and Extracochlear Electrocochleography During Electrode Insertion

(1) To correlate simultaneously recorded intra- and extracochlear electrocochleography (ECochG) signals during electrode insertion into the cochlea, (2) to track changes in the ECochG signal during insertion and removal of an electrode, and (3) to correlate the findings with the preoperative residual hearing. We hypothesized that intracochlear ECochG recordings show signal changes not reflected in simultaneous extracochlear ECochG recordings. During cochlear implantation in human cochlear implant recipients, a short, slim, custom-made electrode was inserted and removed in a stepwise manner. At each step, ECochG recordings were simultaneously recorded by an extracochlear electrode near the round window and via the inserted electrode. The acoustic stimulus was a 500 Hz tone burst at 110 to 130 dB SPL. The mean amplitude difference between intra- and extracochlear ongoing ECochG responses was 14 dB (range 9 to 24 dB; n = 10) at the beginning of insertion. Intracochlear ECochG responses were larger in all cases. Extracochlear ECochG responses remained stable while intracochlear recordings showed large variations regarding amplitude and phase during the electrode array insertion. Intracochlear signal changes during insertion were reversible with retraction of the electrode. There were only weak to moderate (rs = 0.006 to 0.4), nonsignificant correlations of residual preoperative hearing with maximum amplitudes and amplitude changes during electrode insertion and removal in intracochlear recordings. Signals in intracochlear ECochG recordings are reliably larger than ECochG signals recorded simultaneously from an extracochlear location. Intracochlear ECochG recordings show reversible amplitude and phase changes during insertion, not reflected in simultaneous extracochlear ECochG recordings. Such changes are most likely due to the movement of the recording electrode in relation to the signal generators. Residual high-frequency hearing is associated with larger ECochG signal amplitudes. Modeling of expected intracochlear ECochG changes during electrode insertions may allow detection of cochlear trauma in the future.

Detection of Electrode Proximity to the Cochlea Wall Based on Impedance Variation: a Preliminary Computational Study

The electro anatomy of the cochlea plays a crucial role in hearing, where damage to the cochlea may cause hearing loss. Cochlear implants provide hearing to severe or profound hearing-impaired individuals. The accurate insertion of electrodes into the cochlea is important. If misplaced it may lead to further damage (insertion trauma). Visual inspection of the electrode array insertion is limited and relies on the experience of the surgeon. Assisted real time guidance in positioning the electrode array in the cochlea during insertion is needed. Using an advanced computational model of the cochlea accounting for different tissue layers, impedance variations at different electrode distances from the cochlear wall were simulated. Preliminary simulations suggest that the variations may be used to detect the proximity of the electrodes to the cochlea wall.

Magnetically Steered Robotic Insertion of Cochlear-Implant Electrode Arrays: System Integration and First-In-Cadaver Results.

Cochlear-implant electrode arrays (EAs) must be inserted accurately and precisely to avoid damaging the delicate anatomical structures of the inner ear. It has previously been shown on the benchtop that using magnetic fields to steer magnet-tipped EAs during insertion reduces insertion forces, which correlate with insertion errors and damage to internal cochlear structures. This paper presents several advancements toward the goal of deploying magnetic steering of cochlear-implant EAs in the operating room. In particular, we integrate image guidance with patient-specific insertion vectors, we incorporate a new nonmagnetic insertion tool, and we use an electromagnetic source, which provides programmable control over the generated field. The electromagnet is safer than prior permanent-magnet approaches in two ways: it eliminates motion of the field source relative to the patient's head and creates a field-free source in the power-off state. Using this system, we demonstrate system feasibility by magnetically steering EAs into a cadaver cochlea for the first time. We show that magnetic steering decreases average insertion forces, in comparison to manual insertions and to image-guided robotic insertions alone.

Evaluation of Insertion Forces and Cochlea Trauma Following Robotics-Assisted Cochlear Implant Electrode Array Insertion.

The objective was to evaluate the effect of cochlear implant (CI) insertion technique on electrode insertion forces and intracochlear trauma. We hypothesize that robotics-assisted insertions will reduce insertion forces and intracochlear trauma compared with manual insertions. Variability in CI outcomes exists across patients, implant centers, surgeons, and electrode types. While surgical techniques that reduce electrode insertion trauma are well established, insertion trauma remains one contributing factor to variability in CI outcomes. Previous work demonstrates that micromechanically controlled insertion tools reduce both maximum insertion forces and insertion variability compared with manual insertions. CI electrode insertions were performed either by hand (n = 12) or utilizing a robotics-assisted tool (n = 12) in fresh frozen, human cadaveric cochleae using electrodes from four different CI manufacturers. Electrodes array insertion forces were additionally evaluated in benchtop cochlea models. Following cadaveric insertions, samples were imaged via high resolution x-ray microscopy to evaluate electrode position and intracochlear trauma events based on a modified Eshraghi scale. Electrode array insertions performed by robotics-assisted system showed significantly lower insertion forces and variability. Manual electrode array insertions had a significantly higher overall trauma score of 3.1 ± 2.0 compared with 0.9 ± 1.0 for robotics-assisted insertions. Robotics-assisted insertions had higher rate of basilar membrane elevations while manual insertions showed higher rates of severe trauma events. The robotic-assisted insertion system reduced trauma events associated with CI electrode insertions in cadaveric cochleae compared with manual insertions. Surgical devices which help to precisely and more consistently insert electrodes may improve CI outcomes and hearing preservation.

Successful partial cochlear implantation on a patient with relapsing polychondritis

The author reports on a case of relapsing polychondritis in which partial insertion of a cochlear implant has been successful. A woman with known relapsing polychondritis gave a history of increasingly severe auditory loss of sensorineural type occurring bilaterally. Previous repeated treatments with corticosteroids and immunosuppressive medications had been attempted. A right-sided cochlear implantation with partial electrode array insertion was carried out due to the patient's cochlea being obliterated. The outcome was excellent and the improvement in hearing was maintained. Relapsing polychondritis (RP) is a rarely-seen disorder, the aetiology of which is obscure, but which results in inflammation within cartilage throughout the entire body. The cochlea may become obliterated by this process. Cochlear implantation may be needed in such circumstances. The successful outcome in this case shows a potential role for cochlear implantation in individuals with inner ear disorders produced by immune disorders or relapsing polychondritis.

A microfabricated, 3D-sharpened silicon shuttle for insertion of flexible electrode arrays through dura mater into brain

Objective. Electrode arrays for chronic implantation in the brain are a critical technology in both neuroscience and medicine. Recently, flexible, thin-film polymer electrode arrays have shown promise in facilitating stable, single-unit recordings spanning months in rats. While array flexibility enhances integration with neural tissue, it also requires removal of the dura mater, the tough membrane surrounding the brain, and temporary bracing to penetrate the brain parenchyma. Durotomy increases brain swelling, vascular damage, and surgical time. Insertion using a bracing shuttle results in additional vascular damage and brain compression, which increase with device diameter; while a higher-diameter shuttle will have a higher critical load and more likely penetrate dura, it will damage more brain parenchyma and vasculature. One way to penetrate the intact dura and limit tissue compression without increasing shuttle diameter is to reduce the force required for insertion by sharpening the shuttle tip. Approach. We describe a novel design and fabrication process to create silicon insertion shuttles that are sharp in three dimensions and can penetrate rat dura, for faster, easier, and less damaging implantation of polymer arrays. Sharpened profiles are obtained by reflowing patterned photoresist, then transferring its sloped profile to silicon with dry etches. Main results. We demonstrate that sharpened shuttles can reliably implant polymer probes through dura to yield high quality single unit and local field potential recordings for at least 95 days. On insertion directly through dura, tissue compression is minimal. Significance. This is the first demonstration of a rat dural-penetrating array for chronic recording. This device obviates the need for a durotomy, reducing surgical time and risk of damage to the blood-brain barrier. This is an improvement to state-of-the-art flexible polymer electrode arrays that facilitates their implantation, particularly in multi-site recording experiments. This sharpening process can also be integrated into silicon electrode array fabrication.

Investigating variability in cochlear implant electrode array alignment and the potential of visualization guidance.

Background Internal cochlear anatomy is difficult to discern from external inspection, hindering cochlear implant electrode insertion. Methods A user study characterized the repeatability of standard surgical technique and examined the role of visual inspection and guidance cues in reducing electrode array insertion misalignment. Results Without guidance, a large spread in angles of insertion, up to 30°, was observed, highlighting the need for intraoperative guidance. Visual inspection did not significantly improve overall orientation, suggesting the need for alternate intracochlear visualization methods and/or increased training to effectively improve surgeon understanding of the visualized images. Visual cues and guidance software increased repeatability of surgeon performance, reducing one metric of repeatability to ±2°. Conclusions This study establishes a baseline for surgeon variability in cochlear implant insertion and supports the need and lays the groundwork for future intraoperative guidance techniques.

A New Lateral Wall Electrode: Evaluation of Surgical Handling, Radiographic Placement, and Histological Appraisal of Insertion Trauma.

To describe histologic and radiographic findings associated with insertion of a new lateral wall electrode in human temporal bones, as well as quantify the ease of insertion as characterized by multiple cochlear implant surgeons. Multi-institutional cadaveric study. The Slim J electrode was inserted in cadaveric temporal bones via a standard mastoidectomy and facial recess approach. Insertion was performed by five cochlear implant surgeons with no previous experience with the Slim J electrode array. Electrode array insertion was performed via a round window, an extended round window, or a cochleostomy approach. Intracochlear trauma, and angular insertion depth was assessed histologically and radiologically, respectively, after placement of the Slim J electrode array. Scala tympani insertion was accomplished in all 40 specimens. Thirty-eight specimens (95%) showed minimal trauma (Esrhaghi grade 0 or 1). One patient had rupture of basilar membrane (grade 2 trauma) at 380 degrees. One patient had grade 4 trauma with scalar translocation beginning at 210 degrees. The mean angular insertion depth was 416.4 degrees (range: 338.7-509.2 degrees, SD 44 degrees). Surgical handling was described as easy in 38 cases (95%). In a human cadaveric model the lateral wall Slim J electrode produced minimal intracochlear trauma that was positioned completely within the scala tympani in 97.5% of cases.

Human Otopathology of Cochlear Implant Drill-out Procedures.

Human otopathology following drill-out procedures for cochlear implantation (CI) in cases with labyrinthitis ossificans (LO) has not been previously described. This study uses the high sensitivity of histopathology to (1) evaluate surgical drill-out technique with associated intracochlear findings and (2) quantify spiral ganglion neuron populations in a series of patients with LO who underwent CI. Retrospective otopathology study. Otopathology laboratory. Temporal bone (TB) specimens from cases with evidence of preoperative intracochlear fibroossification that required a drill-out procedure for CI electrode array insertion were included. All cases were histopathologically evaluated and 3-dimensional reconstructions of the cochleae were performed to interpret drilling paths and electrode trajectories. Five TB specimens were identified, of which 4 underwent drill-out of the basal turn of the cochlea and 1 underwent a radical cochlear drill-out. In multiple TBs, drilling was imprecise with resultant damage to essential structures. Two TBs showed injury to the modiolus, which was associated with substantially decreased or even absent neuronal populations within these areas. In addition, 2 cases with inadequate drill-out or extensive LO of the basal turn resulted in extracochlear placement of electrode arrays into the vestibule due to persistent obstruction within the basal turn. Otopathology highlights the challenges of drill-out procedures in cases of LO. Imprecise drilling paths, due to distortion of normal cochlear anatomy, risk injury to the modiolus and adjacent neurons as well as extracochlear placement of electrode arrays, both of which may contribute to poorer hearing outcomes.

Changes of Electrocochleographic Responses During Cochlear Implantation Presented at the Annual Meeting of ADANO 2016 in Berlin.

To assess by electrocochleography (ECoG) at which times during cochlear implantation changes of cochlear function occur. Tone bursts with a frequency of 500 or 750 Hz were used as acoustic stimuli. The recording electrode was placed on the promontory and left in an unchanged position for all ECoG recordings. Eight subjects were included. After opening the cochlea, an increase of the amplitude of the ECoG signal was detectable in four subjects (mean change 3.9 dB, range from 0.2 to 10.8 dB). No decreases were detectable after opening the cochlea or during the first half of the insertion of the CI electrode array (mean change 0.5 dB, range from -2.2 to 1.6 dB). During the second half of the insertion, the amplitude of the ECoG signal decreased in four subjects (mean change -2.5 dB, range from -0.04 to -4.8 dB). If a decrease occurred during the second half of the insertion, then the decrease continued in the earliest phase after insertion of the CI electrode array (mean change -2.1 dB, range from -0.5 to -5.8 dB). Pressure changes inside the cochlea can lead to an increase of ECoG signals after opening the cochlea. If detectable, then a decrease of ECoG signals occurs during the second half of the insertion of the CI electrode array and continues in the earliest phase after completed insertion. These findings suggest that cochlear trauma occurs toward the end of the insertion and that trauma-dependent postoperative mechanisms contribute to postoperative hearing loss.

Investigating the Effect of Cochlear Size in Insertion of Electrode Depth in Patients with Cochlear Implantation evaluated by CT-Scan

Background Cochlear implant surgery is an invasive procedure for patients with bilateral Sensorineural hearing loss and may cause some risks such as cochlear damage. We aimed to evaluate the effectiveness of cochlear measures obtained by computed tomography (CT) scan in predicting depth of cochlear implant insertion. Materials and Methods This study was conducted in a retrospective and cross-sectional study on 39 patients undergoing cochlear implantation with MED-EL Device. High-resolution radiographs provided preoperative by CT-Scan were used to determine electrode array insertion depth and diameter of the cochlea’s basal turn. The insertion was considered deep when the electrode was placed at least 22 mm into the cochlea. Demographic data, CT-Scan results and cochlear implantation outcomes (deep or shallow) were evaluated. Data were analyzed by SPSS22 software and the significance level was less than 0.05. Results The mean age of patients was 8.026±1.77 years. The depth of insertion of the electrode in 34 (87.18%) patients was deep and in 5 (12.82%) patients was shallow that the difference was statistically significant (P<0.05). Mean size of cochlear in deep group was significantly higher than shallow group (5.89±0.39 vs. 5.2±0.25 mm respectively). There was a significant relationship between age and gender of patients in deep group, which females and patients with lower age reported a higher level of shallow insertion. Conclusion The results of present study showed the efficacy of using CT-Scan before surgery to predict the depth of implant placement and help it to select the appropriate prosthesis.

Role of CT and MRI in Assessment of Temporal Bone Pre and Post Cochlear Implantation

Background: MDCT and MRI plays a critical role in evaluation and management of different causes of hearing loss which require many therapeutic techniques including cochlear implantation. MDCT has proven its efficacy in the postoperative imaging of cochlear implant patients. CT confirms the intracochlear position of the implant. It has also been shown that malpositioning and kinking can be detected by CT imaging. Aim of the Work: To evaluate the role of various imaging modalities (CT and MRI) in pre and postoperative evaluation of cochlear implant candidates. Patients and Methods: The study included a total of 20 patients referred to the Radiodiagnosis Department from the E.N.T Department in EL-Galaa Military Hospital. The patients had bilateral severe to profound sensorineural hearing loss (SNHL). CT and MRI were done for assessment of the cochlear state prior to the cochlear implantation operation. Postoperative CT was done to underline the position of implanted electrode. Results: The study was performed on 8 males (40%) and 12 females (60%). Only 17 patients (85%) underwent cochlear implantation, the other 3 cases (15%) were diagnosed as Michel deformity, Cochlear hypoplasia and Labyrinthine ossificans. Full electrode array insertion was reported in all cases underwent of cochlear implantation. Conclusion: Preoperative CT and MRI assessment is critical for determining implant candidacy. Postoperative CT confirms the intracochlear position of the implant

Anisotropic etching in (3 1 1) Si to fabricate sharp resorbable polymer microneedles carrying neural electrode arrays

Polymer microneedles that get resorbed after insertion in the body have several interesting applications, for example in the insertion of ultra-flexible electrode arrays in neural tissue. In this work, we explore the use of molds created by etching in (3 1 1) silicon as a basis for the fabrication of such microneedles. Such molds can be etched anisotropically to much sharper angles compared to standard (1 0 0) silicon. It is demonstrated that sharp poly lactic-co-glycolic acid (PLGA) microneedles can be fabricated using the molds. It is also shown that by simple thermal bonding the fabricated PLGA microneedles can be combined with a ultra-flexible polyimide-based thin-film electrode array.

Role of computed tomography and magnetic resonance imaging in the assessment of temporal bone pre-cochlear and postcochlear implantation

Introduction Multidetector computed tomography (CT) and MRI play a critical role in the evaluation and management of different causes of hearing loss, which require many therapeutic techniques including cochlear implantation. Multidetector CT has proven its efficacy in the postoperative imaging of cochlear implant patients. CT confirms the intracochlear position of the implant. It has also been shown that malpositioning and kinking can be detected by CT imaging. Aim of the work To evaluate the role of various imaging modalities (CT and MRI) in the preoperative and postoperative evaluation of cochlear implant candidates. Patients and methods The study included a total of 20 patients referred to the Radiodiagnosis Department from the ENT Department in Al Galaa Military Hospital. CT and MRI were performed for the assessment of the cochlear state before cochlear implantation operation. Postoperative CT was done to underline the position of the implanted electrode. Setting and design This study involves prospective, randomized, controlled trials. Ethics Informed consent from a parent or guardian. Results This study included 20 patients with bilateral severe to profound sensorineural hearing loss. The study was performed on eight (40%) men and 12 (60%) women. Only 17 (85%) patients underwent cochlear implantation, the other three (15%) cases were diagnosed as Michel deformity, Cochlear hypoplasia, and Labyrinthine ossificans. Full electrode array insertion was reported in all cases who underwent cochlear implantation. Conclusion Preoperative CT and MRI assessment is critical for determining implant candidacy. Postoperative CT confirms the intracochlear position of the implant.

128-multidetector CT: For assessment of optimal depth of electrode array insertion in cochlear implant operations

ObjectiveTo assess the diagnostic reliability of MDCT in pre-operative evaluation of cochlear implant candidates and post-operative, estimation of depth of insertion. Material and methodsThe study includes 40 patients (18 males and 22, females); classified into 2 groups: group A (20 patients): cochlear, implant device was Nucleus-22. Group B (20 patients): device was MED-EL.Cochlear length (CL) and cochlear height (CH) were measured pre-operatively by 128-multidetector CT. Electrode length (EL) and insertion, depth angle (α) were measured post-operatively by MDCT. ResultsGroup A: mean CL was 9.1 mm ± 0.4 SD; mean CH was 4.1 ± 0.3 SD; mean EL was 18 ± 2.7 SD; mean α angle was 299.05 ± 37 SD. Significant, statistical correlation (P < 0.05) was found between preoperative CL and, post-operative EL. Significant statistical correlation was found between, EL and α angle (r2 = 0.7). Group B: mean CL was 9.1 mm ± 0.3 SD; mean CH, was 4.1 ± 0.4 SD; mean EL was 27 ± 2.1 SD; mean α angle was 287.6 ± 41.7, SD. Significant statistical correlation was found between CL and EL & α angle. ConclusionCochlear length is a reliable prognostic parameter in, prediction of the depth of electrode array insertion.

Safety Studies for a 44-Channel Suprachoroidal Retinal Prosthesis: A Chronic Passive Study.

Following successful clinical outcomes of the prototype suprachoroidal retinal prosthesis, Bionic Vision Australia has developed an upgraded 44-channel suprachoroidal retinal prosthesis to provide a wider field of view and more phosphenes. The aim was to evaluate the preclinical passive safety characteristics of the upgraded electrode array. Ten normal-sighted felines were unilaterally implanted with an array containing platinum electrodes (44 stimulating and 2 returns) on a silicone carrier near the area centralis. Clinical assessments (color fundus photos, optical coherence tomography, full-field electroretinography, intraocular pressure) were performed under anesthesia prior to surgery, and longitudinally for up to 20 weeks. Histopathology grading of fibrosis and inflammation was performed in two animals at 13 to 15 weeks. Eight animals showed safe electrode array insertion (good retinal health) and good conformability of the array to the retinal curvature. Eight animals demonstrated good mechanical stability of the array with only minor (<2 disc diameters) lateral movement. Four cases of surgical or stability complications occurred due to (1) bulged choroid during surgery, (2) hemorrhage from a systemic bleeding disorder, (3) infection, and (4) partial erosion of thin posterior sclera. There was no change in retinal structure or function (other than that seen at surgery) at endpoint. Histopathology showed a mild foreign body response. Electrodes were intact on electrode array removal. The 44-channel suprachoroidal electrode array has an acceptable passive safety profile to proceed to clinical trial. The safety profile is expected to improve in human studies, as the complications seen are specific to limitations (anatomic differences) with the feline model.

Incomplete and false tract insertions in cochlear implantation: retrospective review of surgical and auditory outcomes.

To evaluate incidence, demographics, surgical, and radiological correlates of incomplete and false tract electrode array insertions during cochlear implantation (CI). To evaluate outcomes in patients with incomplete electrode insertion (IEI). Retrospective analysis. Otology and skull base center. Charts of 18 patients (19 ears) with incomplete or false tract insertions of the electrode array were evaluated who underwent CI, with at least 1 year follow-up (from 470 cases). Demographic findings, etiologies, pre-operative radiologic findings, operative records, post-operative plain radiographic assessment for extent of electrode insertion, and switch-on mapping were evaluated. Audiological outcomes were evaluated using maximum and last recorded vowel, word, sentence, and comprehension scores for patients with IEI. Incidence of insertional abnormalities was 4.25% with 17 instances of incomplete and 2 cases of insertion into superior semicircular canal. Mean age and duration of deafness were 55.18 ± 4.62 and 22.12 ± 5.71years. Etiologies in the IEI group were idiopathic, otosclerosis, meningitis, chronic otitis media (COM), temporal bone fractures, and Neurofibromatosis-2. 29.4% cases had cochlear luminal obstruction. Mean radiological and active electrophysiological length of insertion was 20.49 ± 0.66 and 19.49 ± 0.88mm, respectively. No significant correlation was observed between audiological outcomes and insertional length except in time to achieve maximum word scores (p=0.04). Age at implantation had significant correlations with last recorded word and comprehension scores at mean follow-up of 42.9 months, and with time to achieve maximum auditory scores. IEI during cochlear implantation using straight electrodes can occur with or without cochlear luminal obstruction. Age plays an important role in the auditory rehabilitation in this patient subset.