Medical/Surgical Issues
Thursday, December 11, 2014
Session 1: Pediatric CI: Surgical Considerations & Techniques
ACI2014
Comparison of Forces Required To Traverse the Inter-scalar Partition In Human Cochleae with Surgeon Force Tactile Perception Thresholds
D. Schuster, MD1 , L. B. Kratchman, BS2 , R. F. Labadie, MD,FACS,Ph.D.1,3
1Vanderbilt University Medical Center, Department Of Otolaryngology, Nashville, TN USA ; 2Vanderbilt
University, Department Of Mechanical Engineering, Nashville, TN USA ; 3Vanderbilt University, Department
Of Biomedical Engineering, Nashville, TN USA
Topic: Surgery/Medical
Keywords: Medical/Surgical Issues , Complications
Introduction: Intracochlear trauma represents one potential cause of suboptimal hearing outcomes in cochlear implant (CI) patients. Little is known about the forces required for a CI electrode array to traverse from scala tympani (ST) to scala vestibuli (SV). Additionally, it is unknown whether surgeons can feel such electrode displacement occurring, because there is no data evaluating surgeon tactile perception thresholds performing an analogous task. We aimed to develop methods to measure both the force required to rupture the inter-scalar partition (ISP) of fresh human cochleae and tactile force perception thresholds of surgeons performing a task analogous to CI electrode insertion.
Methods: Fresh (post mortem<120 hours), non-fixed, never-frozen human temporal bones underwent preparation consisting of surgical isolation of the cochleae and exposure of the osseous spiral lamina, basilar membrane and Reissner’s membrane, collectively denoted as the ISP, by removing bone covering scalae tympani and vestibuli without disrupting medial or lateral bony attachments. Each isolated cochlea was mounted to a force sensor, which was used to measure force as a 300 µm diameter ball-tipped probe was advanced at 1mm/sec through the ISP. Independently, surgeons completed force perception testing using Semmes-Weinstein Monofilaments (SWM), which are nylon filaments with calibrated buckling forces. Wearing a single pair of surgical gloves, surgeons were visually blinded and given SWM handles in pairs with each pair consisting of (i) a handle with a SWM and (ii) a negative control (handle without a SWM). Participants advanced the handle towards a flat surface and reported whether they could feel (i) or (ii). This method of two-alternative forced choice combined with a 3-down 1-up staircase (3 correct answers moves to a smaller SWM and 1 incorrect answer moves to a larger SWM) was performed with 25 pairs of SWMs. Each threshold was calculated based on at least 2 complete staircase reversals.
ACI2014
Apical versus Non-Apical Electric Stimulation of the Cochlea
H. Pillsbury, MD1 , M. Dillon,AuD1 , M. Adunka,AuD2 , E. King,AuD2 , O. Adunka, MD1 , C. Buchman, MD1
1University Of North Carolina At Chapel Hill, Otolaryngology/Head And Neck Surgery, Chapel Hill, NC
USA; 2UNC Health Care, Audiology, Chapel Hill, NC USA
Topic: Surgery/Medical
Keywords: Medical/Surgical Issues
Introduction: Postoperative speech perception may be influenced by various factors, including electrode array insertion depth. In theory, a deeper electrode insertion could offer better low-frequency representation although at an increased risk of surgical trauma. Previous studies investigating the effect of electrode insertion depth on postoperative outcomes have yielded conflicting results. These investigations have mostly utilized acute electrode deactivation methods within subjects implanted with deeply inserted electrode arrays. This experimental design suffers from limited listening experience with the modified maps and reduced channel numbers because of deactivation. Generalizations across subjects are further complicated by an inability to control for surgically-induced trauma. Similarly, comparisons across manufacturers have the limitations of differences in electrode array design, number and spacing of active electrodes, and signal coding strategy. The present study aimed to assess the effect of apical cochlear stimulation while controlling for signal coding strategy, electrode number and the presence of surgical resistance and basal buckling.
Methods: Subjects were conventional cochlear implant candidates scheduled to undergo surgery. They were randomly assigned to receive either the standard (26.4 mm) or medium (20.9 mm) electrode array. During the surgical procedure, surgeons indicated the surgical approach, insertion depth, level of resistance experienced during insertion, and evidence of basal buckling. Speech perception was assessed prior to surgery and at 1, 3, 6, 9, and 12 months post-initial activation. Test materials included HINT sentences (quiet, SNR+10), and CNC words.
Results: Thirteen subjects participated, with 7 receiving the standard array and 6 the medium array. There was no difference in age at implantation or duration of deafness. There was a difference between
preoperative unaided CNC word scores, with those implanted with the medium array achieving higher speech perception scores. Postoperatively, all subjects experienced an improvement in aided speech perception abilities in both quiet and noise. Interim analysis necessitated discontinuation of subject enrollment, finding a trend for improved speech perception performance (p=0.07) for the standard array cohort. Inclusion of speech perception results reviewed retrospectively of standard recipients not participating in the study found this difference to be significant.
Conclusion: Electrode insertion depth may influence speech perception acquisition within the first months of listening experience. Additional investigations are needed to determine the influence of electrode length in combination with other medical/surgical and auditory variables.
ACI2014
The Tight Subperiosteal Pocket without Fixation for Internal Receiver-Stimulator Placement During Cochlear Implantation
A. D. Sweeney, MD1 , M. L. Carlson1 , C. V. Valenzuela1 , G. B. Wanna1 , A. Rivas1 , M. L. Bennett1 , D. S. Haynes1
1Vanderbilt University Medical Center, Otolaryngology - Head And Neck Surgery, Nashville, TN USA
Topic: Surgery/Medical
Keywords: Alternative Surgical Approaches , Medical/Surgical Issues
Introduction: In the past decade, reports of cochlear implantation using smaller incisions and less-rigid fixation of the receiver and stimulator (RS) have emerged. More recently, a technique was described in which the receiver and processor were placed into a fitted, subperiosteal pocket in the traditional location without a bony “well” or suture fixation. We sought to examine the physical stability of cochlear implant reciever/stimulators when the devices were placed into a tight subperiosteal pocket without rigid fixation.
Methods: Retrospective series from a single tertiary academic referral center. All primary cochlear implant surgeries utilizing the tight subperiosteal pocket without additional fixation were included. Primary outcome measures included RS migration, prevalence of flap complications and device failure, and time difference comparing the conventional bony well and trough technique to use of a tight subperiosteal pocket.
Results: 223 ears (average age 45.6 years, 27.8% less than 18 years of age) met inclusion criterion and were analyzed. At a mean follow-up of 18.2 months, one patient experienced receiver/stimulator migration; however none have required revision surgery for this reason to date. One patient experienced a hematoma that was managed with observation. One patient developed a surgical site infection that resolved following surgical exploration and intravenous antibiotics. The subperiosteal pocket technique resulted in a 19.2% reduction in total operative time compared to conventional RS placement methods (p<0.01).
Conclusion: The tight subperiosteal pocket without fixation is a safe, durable and time saving technique for RS placement during cochlear implantation. Notably, the prevalence of device migration was exceedingly low, and none have required revision surgery for device drift.
ACI2014
Sonic Weld: A Novel Approach To Anchoring Cochlear Implants, Case Series And Literature Review
M. F. Klein, MD,BS , A. Ho, MD,MBBS(UK), MSc, FRCS (ORL-HNS),1 , B. P. Chang, BS1
1University Of Alberta, Surgery/Otolaryngology/University Of Alberta, Edmonton, AB Canada
Topic: Technology
Keywords: Cochlear Implant Hardware
Introduction: A fundamental component of Cochlear Implant (CI) surgery is the fixation of the
receiver/stimulator (R/S). Without adequate fixation, patients are at risk of device migration, and wound complications. Over the years, many methods of CI fixation have been described. Things to consider when choosing a technique for securing the R/S are the time required to perform the procedure, and the possible complications and their likelihood of occurring.
Methods: In 2013, fifteen consecutive pediatric patients underwent cochlear implantation completed by the same surgeon, AH, who performed the procedure according to our standard method. Resorbable
biodegradable poly (D,L) lactic acid (PDLLA) pins were used in conjunction with standard methods of securing the R/S. (SonicWeld; KLS Martin – Endobrow Pin). Two pins were used for each patient. The anchored monofilament sutures were then tied over the anterior portion of the R/S. Following the surgery, patients were seen at 3 weeks, 6 weeks, and again at 6 months. The surgical site and incisions were monitored specifically for signs of cochlear implant migration, allergic reaction, infection, and wound dehiscence.
Results: 15 Consecutive patients from January 2013 to April 2014, age 1 year to 11 years old underwent cochlear implantation using this fixation technique. The Sonic Weld pins were easy to use and effective at anchoring the cochlear implants in all fifteen of the patients in our series. Follow-up as described showed no device migration. No adverse reaction, such as infection, allergic reaction or wound dehiscence, was observed. Range of follow-up was from 1 to 8 months. No patients were lost to follow-up. The method was efficient, and was appreciably shorter in duration than previous methods used by our group, with less perceived risk to patients. The patients in the study had no complications or problems (related to the Sonic Weld device or otherwise), and did well postoperatively. No patient had a reaction to the endobrow resorbable fixation pins used.
Conclusion: This is the largest case series to date using this new technology for cochlear implant fixation. The Sonic Weld Endobrow resorbable fixation pins is an effective alternative to current methods used for anchoring cochlear implant devices. A future topic of study may be a time comparison with other methods. Additionally, an analysis of cost may be useful.
ACI2014
Factors Influencing Operative Times for Pediatric and Adult Cochlear Implantation
E. D. Kozin, MD1 , S. Puram, MD,Ph.D.1 , R. Sethi, MD,MPH1 , S. Gulati, BA1 , E. Hight, MS1 , S. Gray, MD1 , M. Cohen, MD1 , D. Lee, MD1
1Harvard Medical School / Massachusetts Eye And Ear Infirmary, Otolaryngology, Boston, MA USA
Topic: Economics and Public Policy
Keywords: Public Policy Concerns, Health Economics
Introduction: Surgical education remains an important mission of academic medical centers. Financial pressures, however, may disincentivize surgical education in favor of improved operating room (OR) efficiency. Few studies have examined operative times for cochlear implantation (CI) in the academic setting with a goal of identifying predictors of case length. Objective: Herein, we aim to 1) compare procedure duration for pediatric and adult cochlear implantation, and 2) assess whether resident participation, among other factors, influences OR efficiency.
Methods: We retrospectively reviewed total OR and procedural times for isolated unilateral implants over a five-year period (2009-2013) in children and adults. We included cases that had electronic data available and supervised or performed by one of 14 surgeons at a single tertiary care center. Total operating and procedural times with and without trainee participation were compared. Multivariable linear regression analyses were also used to identify predictors of procedural time, namely American Society of
Anesthesiologists (ASA) physical classification, age, gender, ethnicity, day of week, pediatric designation, presence of a trainee and surgeon identity.
Results: We identified a total of 455 surgical procedures (n = 35 pediatric, n = 420 adult) cases. Mean total OR time for adults was 192.4 minutes (SD=58.0) vs. 208.1 minutes for pediatric (SD=67.3), p=0.1303. There was no difference in total OR time (196.3 minutes [SD=56.9] with residents, 183.8 [SD=65.0] without, p=0.065). However, resident involvement in CI cases resulted in significantly longer total procedural time (149.9 minutes [SD=54.9] with residents, 136.6 minutes [SD=59.9] without, p<0.05). Surgeon identity was also associated with differences in procedural time (p<0.001). Among all cases, patient age, gender, ASA classification, pediatric designation and day of week had no significance on length of case.
Conclusion: We demonstrate similar total operative times among pediatric and adult cochlear implant cases. Two major predictors of total and procedural OR times are surgeon identity and resident participation. Resident participation resulted in longer procedural time, however, presence of a resident had minimal effect on total OR time. Other factors, including gender, patient age, pediatric designation, ASA classification, and day of week had no effect on case length. Few published data exist on length of cochlear implantation in the pediatric population. Our data may be instructive for comparative analyses and has implications for surgical education and operative planning.
ACI2014
Factors leading to variation in cochlear implantation surgical times
M. L. Bennett, MD,FACS1 , R. Labadie1 , M. Dietrich1
1Vanderbilt University Medical Center, Otology, Nashville, TN USA
Topic: Surgery/Medical
Keywords: Alternative Surgical Approaches
Introduction: Cochlear implantation surgery has changed dramatically over the last 10 years. In addition to surgical incisions becoming smaller, many surgeons have abandoned fixation and well drilling. In academic centers, other factors including both patient comorbidities and the level of resident or fellow participation impact the timing of cochlear implantation. Objective: The objective is to analyze the timing for cochlear implantation, identifying key factors which lengthen or shorten surgical times.
Methods: Retrospective study of 635 consequtive implants over 5 years from 2007 until 2012. Surgeries were performed by 4 surgeon. Patient charts and operative records were analyzed for factors which may contribute to surgical timing including medical comorbidies, level of resident participation, fellow
participation, use of CRNA, and surgical site (outpatient vs inpatient)
Results: The results are currently in analysis. We aim to show for each individual surgeon's surgical times vary depending on resident coverage, resident level of training, use of CRNA, anatomical variations, and medical comorbidities. The initial results show a dramatic initial decrease in surgical times after 10 implants and a subsequent lengthening of surgical times after completion of 50 implants. These timing differences are thought to originate from intial increased competency followed by allowance of increased resident participation.
Conclusion: Many factors affect the operative intervention for cochlear implantation. Using an equation, we can successfully predict proper surgical timing.
ACI2014
Re-implantation in children – 22 year review of aetiology, management and outcomes
C. H. Raine, MD,BS,MS,FRCS1 , J. P. Baren1 , C. Totten1 , J. M. Martin1
1Yorkshire Auditory Implant Service, Bradford, West Yorkshire United Kingdom
Topic: Surgery/Medical
Keywords: Revision Surgery, Re-Implantation, Complications
Introduction: Cochlear implants (CI) are built to high specifications and offer significant benefit to patients with congenital and acquired severe to profound hearing loss. Unfortunately a proportion of CIs require replacement for technical or medical reasons, leading to natural anxieties for patients and their families. Objective: A review of prospectively collected data of children who had required revision surgery resulting in re-implantation. The aim was to analyze demographics, causation and overall outcomes of safety and audiological performance following revision surgery.
Methods: Medical notes of 50 children (under 18 years) requiring re-implantation between 1990-2013 were evaluated for demographic information, indications for initial CI and surgical time intervals for initial and re-implantation surgery. Manufacturer failure analysis reports were reviewed and used to classify the reason for failure according to the European Consensus Statement on Cochlear Implant Failures and Explanation. Results of audiological testing were recorded pre and post re-implantation using the Category of Auditory Performance (CAP) scale, Meaningful Auditory Integration Scale (MAIS) and the McCormick Toy Test.
Results: The overall rate of re-implantation was 10.4% (50/479 patients). This reflects the proportion of children undergoing re-implantation rather than the percentage of devices re-implanted from the population. Two children experienced simultaneous implant failures and one child underwent two re-implantation operations. Classification of device failure was documented as category C (device out of specification) in 76% patients, category B2 (performance decrement, device in specification) in 20% and category D (medical reason for explanation) in 4% of children. The median time to implant failure was 1.98 years and the time interval between confirmation of failure and revision surgery was 0.1 months. There was a notable history of trauma (11 patients; 22%), which typically occurred in a younger age group at both initial device implantation (Median age 2.36 v 3.16 years, P=0.019) and at the time failure was confirmed (Median age 3.94 v 5.61 years, P=0.007). CAP scores remained stable or improved at 6 months following re-implantation in 93% patients, with a reduction by one CAP point observed in 3 children. The MAIS score calculated at school was significantly improved following re-implantation (P=0.019), however there was no difference in the McCormick Toy Test score. No surgical complications were encountered.
Conclusion: Results confirm that cochlear re-implantation is a safe procedure and allows for continuing auditory development in children. Providers need to plan and budget for increasing need for re-implantation as the service provision increases. Learning: Once a CI failure is recognized timely intervention is required especially with unilaterally implanted patients. There are no significant surgical issues with re-implantation.
Session 2: Advancements in Implant Surgery
ACI2014
Robot Assisted Minimally Invasive Cochlear Implantation: Redundancy and Safety
B. Bell, Ph.D.1 , J. Anso1 , N. Gerber1 , T. Williamson1 , K. Gavaghan1 , S. Weber1 , M. D. Caversaccio2
1University Of Bern, ARTORG Center For Biomedical Engineering, Bern, BE Switzerland ; 2University Of
Bern, Department Of ENT, Head, And Neck, Surgery, Bern, BE Switzerland
Topic: Surgery/Medical
Keywords: Robotic Surgery, Computer Assisted Surgery , Alternative Surgical Approaches
Introduction: Alternative blind (minimally invasive) approaches to reach the cochlea (varia, suprameatal) could put the facial nerve unduly at risk. The robotic approach of the University of Bern leverages all information available from the preoperative scan together with process data to ensure the highest probability of a safe surgery. Objective: To report on the redundancy and safety aspects available through process- and neuromonitoring- based estimation of the drill bit relative to the facial nerve in the context of robot assisted, minimally invasive cochlear implantation.
Methods: The robot assisted direct cochlear access (DCA) approach utilizes four small titanium screws in the mastoid posterior to the external auditory canal for use as registration markers. Efficient and accurate planning based on low-dose cone beam CT (CB-CT) data is achieved using a custom-developed planning software. Using this software, the surgeon can efficiently plan a safe and effective trajectory to a desired location on the cochlea. Intra-operatively, the robot arm is mounted directly on the OR table, and the head is fixed non-invasively. A tracking reference is fixed rigidly to the skull, and the position of the head is
registered relative to the robot using the implanted screws. Once registered, the robot automatically moves to the correct drilling axis. A tracking system sends the accurate position of the drill relative to the patient, which allows a dynamic and precise control.
Results: The technical accuracy of the system was previously shown to be on average 0.15 ± 0.08 mm in a laboratory setting using 8 whole head cadaver head specimens. This high accuracy is only one of the aspects of the system which contribute to the safety and reliability of the approach. Process-based pose estimation is a method which can determine the position of a tool within the mastoid by using the drill force history and bone density information to estimate the position of the tool to an accuracy of 0.38 ± 0.16 mm. This estimate is independent of tracking and registration errors, and thus provides redundancy and increased safety. A second safety system, integrated neuromonitoring, utilizes an optimized stimulation probe to detect the proximity of the FN. This system is currently under evaluation in an animal study to determine its effectiveness and reliability.
Conclusion: The high accuracy of the robot assisted approach together with redundant position estimation and real-time facial nerve stimulation offers a robust platform for further research into minimally invasive access to the cochlea for electrode insertion and prepares the way for novel skull-base and otology techniques. The combination of multiple sensor and control technologies provides redundancy regarding facial nerve safety.
ACI2014
Assessment Of The Intra-cochlear Position And Stability Of The Cochlear Implant Electrode Based On Fusion Of MRI And Cone Beam CT
R. J. Stokroos1 , G. Dees1 , M. Van Hoof1
1Maastricht University Medical Center, Department Of Otolaryngology Head And Neck Surgery, Maastricht,
LIMBURG Netherlands
Topic: Surgery/Medical Keywords: Radiology/Imaging
Introduction: One of the important aspects related to the performance with a cochlear implant (CI) is the achievement of consistent electrical coverage with the electrode. Ideally, we would be able to accurately assess the position of the CI electrode in relation to the inner cochlear structures. In our experience, the best segmentation of the scalae is achieved using MRI, which is not possible after CI surgery. Cone Beam CT (CBCT) does provide accurate information about the position of the electrode but the delineation of the scalae is limited by electrode scattering. Here we present an open-source approach that combines CBCT imaging together with MRI. By superimposition of registered volumes with sub voxel accuracy (< 0.2 millimetres), one can benefit from the advantages of both modalities. Repeating the CBCT over time also allows the clinician to diagnose problems such as migration when they arise. The application of this toolset is investigated and applied to investigate the position and stability of a new mid-scalar electrode (Advanced Bionics LLC, Valencia, USA).
Methods: Pre-operatively, a high resolution MRI was made of the cochlea. Surgery was performed with a mid-scalar electrode and afterwards the first CBCT scan was made and registered to the MRI. After 3 months the second CBCT scan was made, registered to the first CBCT and the migration in millimetres was calculated. Registration and segmentation was performed using the open-source packages 3D slicer 4.1 and BRAINSFit.
Results: Superimposition of CBCT with MRI allows for the assessment of the CI electrodes in 3 dimensions. The application of this toolset is illustrated in cases where inner-cochlear abnormalities such as fibrosis affect the position of the electrode which were previously missed on either modality alone. Also the preliminary data of the stability of the mid-scalar electrode will be presented.
Conclusion: In our experience, fusion of CBCT and MRI, is a useful tool for clinicians interested in cochlear implant electrode position after surgery. It is possible to visually and analytically evaluate and benchmark the position of electrodes in representative cochleae, that is in vivo and in cases of inner-ear pathology.
ACI2014
Minimally Invasive Image-guided Cochlear Implantation For Pediatric Patients
R. Balachandran, Ph.D.1 , F. A. Reda2 , J. H. Noble2 , G. S. Blachon1 , B. M. Dawant2 , J. Fitzpatrick2 , R. F. Labadie1
1Vanderbilt University Medical Center, Otolaryngology, Nashville, TN USA ; 2Vanderbilt University,
Electrical Engineering And Computer Science, Nashville, TN USA
Topic: Surgery/Medical
Keywords: Robotic Surgery, Computer Assisted Surgery , Alternative Surgical Approaches
Introduction: A minimally-invasive approach to perform a cochlear implantation (CI) is to drill a narrow, linear path from the lateral skull to the cochlea. To safely drill a path, we can utilize image processing techniques to plan the safe path that targets the cochlea and avoids damage to vital structures such as the facial nerve and custom microstereotactic frame that attaches to bone-implanted markers to constrain the drill along the desired path. Objective: To verify the feasibility of the minimally invasive image-guided CI technique for pediatric patients.
Methods: With institutional review board approval, three fiducial markers were bone-implanted surrounding the mastoid region after the postauricular skin incision was made for a standard CI procedure in the operating room. A low dose CT scan was acquired following which the surgeon performed the
mastoidectomy procedure. In parallel with the mastoidectomy, the CT scan was processed to automatically segment the relevant structures including the labyrinth, scala tympani, scala vestibuli, facial nerve, chorda tympani, external auditory canal, and ossicles. A safe linear trajectory was then computed that targets the scala tympani portion of the cochlea avoiding damage to vital structures. Immediately after this path planning, a custom microstereotactic frame was designed and fabricated such that the frame would mount on the three bone-implanted markers and constrain a drill passing through it along the planned trajectory. The frame was then sterilized and made available to the surgeon before cochleostomy was performed. Prior to cochleostomy, the surgeon mounted the microstereotactic frame on the bone-implanted markers, passed a sham drill bit through the frame, and verified if the drill would safely target the cochlea. An endoscope was used to visualize the drill path.
Results: Thirteen pediatric patients in the age range 1.5 to 8 years participated in this validation study. A safe trajectory was planned for all the patients, and the validation with the custom microstereotactic frame was performed on nine patients. Two patients had malformed cochlea, and the technique provided confirmation of the location for cochleostomy to the surgeon.
Conclusion: It is feasible to perform cochlear implantation using a minimally invasive approach on pediatric patients using image-guided surgical techniques.
ACI2014
Retrofacial Approach to Access The Round Window For Cochlear Implantation Of Malformed Ears
H. G. Rizk, MD1 , B. O'Connell, MD1 , S. Stevens, MD1 , T. Meyer, MD,Ph.D.1
1Medical University Of South Carolina, Otolaryngology- Head Neck Surgery, Charleston, Sc USA
Topic: Surgery/Medical
Keywords: Inner Ear Malformation, Alternative Surgical Approaches , Difficult or atypical patients
Introduction: Cochlear implant surgery is fairly standardized. However, surgeons can be faced with difficult anatomy especially in patients with malformed ears. In difficult cases, a non-traditional approach might be necessary to obtain access to the inner ear in hopes of full implantation and a positive outcome. Objective: Describe and illustrate an alternative approach to the facial recess for cochlear implantation. Identify possible candidates for this approach.
Methods: Retrospective review of two children (3 ears) with malformed temporal bones with inaccessible round windows in which a retrofacial approach was utilized to access the posterior mesotympanum and visualize the round window.
Results: We implanted three ears in two patients with multiple external and middle ear malformations with an aberrant facial nerve or posteriorly-displaced round window niche. The standard facial recess approach did not allow visualization of the round window in one patient, and a bifurcated facial nerve blocked entry in the other. We resorted to a retrofacial approach to access the posterior mesotympanum and proceeded with the surgery through an anterior and inferior cochleostomy or through the round window.
Conclusion: In cases with an aberrant facial nerve or inaccessible round window through a facial recess, the retrofacial approach is a good alternative. It requires a certain level of expertise and familiarity with temporal bone anatomy. The decision to use an unusual approach should be considered prior to surgery, but the ultimate decision might need to be made intraoperatively.
ACI2014
Use of the Flexible CO2 Laser in Hearing Preservation Cochlear Implant Surgery: A Review of the
University of Cincinnati Experience
R. N. Samy, MD,FACS1 , J. S. Golub1 , J. J. Kuhn1
1University Of Cincinnati, Otolaryngology, Cincinnati, OH USA
Topic: Surgery/Medical
Keywords: Hearing Preservation , Complications , Alternative Surgical Approaches
Introduction: Use of the Flexible CO2 Laser in Hearing Preservation Cochlear Implant Surgery: A Review of the University of Cincinnati Experience Ravi N. Samy, MD, FACS, Justin S. Golub, MD, Jeffrey J. Kuhn, MD OBJECTIVES: 1. Explain how to use the CO2 flexible laser to assist with cochlear implant electrode insertion and attempt reduction of insertional trauma 2. Review soft surgery techniques and how to maximize hearing preservation by minimizing intracochlear trauma whether using round window or cochleostomy electrode insertion Introduction: Cochlear implants (CI) have clearly gained acceptance worldwide to treat profound hearing loss in children and adults. As their performance has improved, their indications have been liberalized. Superior CI performance relies not only on advancements in electrode design and processing algorithms but also on proper insertion techniques. Soft surgery techniques are important to treat patients with residual hearing, whether using short or long electrodes or
Hybrid/electroacoustic systems.
Methods: A retrospective review of all adult patients undergoing cochlear implantation with the use of a flexible CO2 laser system over the past 4 years (n=90). Hearing outcomes (hearing preservation and HINT/AzBio scores) and surgical complications were reviewed.
Results: The CO2 laser assisted with both cochleostomy and round window insertions. There were no facial nerve injuries or other surgical complications attributed to the use of the laser. The laser was used with all 3 FDA approved manufacturers’ devices and a variety of electrodes (MedEl, Advanced Bionics, and
Cochlear). The laser was also used in 2 revision surgeries and with both cochleostomy and round window approaches.
Conclusion: The CO2 flexible laser appears safe and is potentially advantageous in cochlear implant surgery. While there are cost considerations with use of the laser, it may be advantageous in hearing preservation and soft surgery techniques. It is possible that with further refinements, the laser may be as useful in CI surgery as it is in stapedotomies.
ACI2014
Insertion Under Water: Cooling the Temporal Bone for Insertion of a New Experimental Shape Memory Cochlear Implant Electrode
O. Majdani, MD,Ph.D.1 , T. H. Lenarz1 , L. Harbach1 , N. Pawsey2 , B. Waldmann2 , T. H. Rau1
1Hannover Medical School, Dept. Of Otolaryngology, Hannover, LOWER SAXONY Germany ; 2Cochlear
Ltd., Sydney, NSW Australia
Topic: Surgery/Medical
Keywords: Alternative Surgical Approaches , Hearing Preservation
Introduction: Currently for residual hearing preservation CI surgery different straight electrodes are used. These are positioned at the lateral wall of the cochlea. Perimidiolar position has been found to result in improved battery life. In addition the stimulation can be more efficient as contacts are closer to the spiral ganglion cells. Furthermore precurled elecrode moves deeper into the cochlea comparing to a same length straight electrode, resulting in higher coverage of the cochlea. Objective: We aimed to include an initially straight inlay of shape memory alloy (NiTinol) into the electrode carrier of the Hybrid-L24 electrode
(Cochlear Ltd., Sydney, Australia). After insertion the straight shaped electrode is designed to curl by shape memory activation at body temperature.
Methods: Different shaped Nitinol-wires were produced. An iterative process for finding the best shape (diameter, length) and alloy for the Nitinol Inlay has been followed. Experiments were performed in a water bath with controlled temperature. The temperature range between the start and finishing phase of the curling of the Nitinol was is around 12°-15°C. The starting temperature of the insertion was defined to be around room temperature (20°C) to avoid a premature curling of the electrode. To provide this condition a sealed temporal bone was placed in the temperature controlled water bath (37°C). A thermometer was placed in the tympanum through the facial recess. The mastoid and tympanum were filled with cool (6°C) water. Insertions of the regular electrodes under cool water were performed to examine the feasibility of underwater insertion.
Results: The first version of the Nitinol inlay had a good ability of the electrode to transform into the memorized curved shape at 37°C. However these began curling even before insertion. The NiTinol alloy was changed to achieve a higher transformation temperature. The premature transformation could be prevented, thus the insertion process was straightforward. However an incomplete curving of the electrode was achieved at 37° C. With filling the mastoid and middle ear with cool (6°C) water, the temperature in Tympanum could be reduced to 14.4°C. After removing the cool water, the temperature raised: It took around 60s to reach 20°C, around 120s to reach 24°C and 300s to reach 30°C. Insertion of Hybrid-L electrodes were performed by 3 different skilled CI surgeons through the round window membrane. All insertions were successful and uneventful.
Conclusion: By replacing the stiffener of a conventional Hybrid-L electrode with a shape memory actuator (Nitinol), a more perimodiolar position could be achieved. For keeping the electrode straight prior to
ACI2014
Modern Aspects of Surgical Approach and Wound Closure in Cochlear Implantation
P. Agha-Mir-Salim, MD,Ph.D.1 , A. Mller1
1Vivantes Klinikum Im Friedrichshain Berlin, ENT Clinic Hearing Center Berlin, Berlin, BERLIN Germany
Topic: Surgery/Medical
Keywords: Medical/Surgical Issues , Revision Surgery, Re-Implantation , Young and Very Young Children
Introduction: Minimal invasive cochlear implantation has especially in pediatric cases various advantages and only low complication rates. Most of the performed surgical approaches are directly through all layers over the implant case and have a visible scar. Simultaneous intraoperative electrophysiological measures are frequently impossible during the wound closure. Objective: We introduce and discuss our experience with a modified retroauricular “Berliner approach”, periosteal flap and three layer wound closure with skin glue. This short retroauricular skin incision and wound closure in 3 layers with overlapping flaps allow simultaneous electrophysiological measurements. The intraoperative handling and postoperative care had to be evaluated and compared to standard procedures.
Methods: 59 cases with bilateral cochlear implantation at the age of 5 months to 16 years were included. We evaluated intraoperative problems with a simultaneous wound closure and measurements. The postoperative results such as postoperative complication rate, visibility and character of the scar were analyzed. Prospectively we recorded in 5 cases intraoperative handling and wound closure time.
Results: The mean mastoid exposure time was 12 minutes. The mean wound closure time was 16 min. In all cases intraoperative audiological measurements were performed simultaneously to the wound closure. Postoperatively only a few patients needed more than one control. In no case sutures needed to be removed. Wound healing was always uncomplicated.
Conclusion: This modified minimal invasive “Berliner approach” for cochlear implantation is a safe procedure and minimizes again the postoperative care. Especially sutures become unnecessary avoiding any inconvenience for parents and patients. Intraoperative simultaneous electrophysiological measures and wound closure were possible in all cases leading to a shorter surgical exposure time.
Session 3: Imaging and Cochlear Implants
ACI2014
Evaluation of a Magnetic Resonance Imaging Only Protocol in the Assessment of Children with Sensorineural Hearing Loss Prior to Cochlear Implantation
S. L. Cushing, MD1,2,5 , K. A. Gordon,M. Aud.1,2,3,5 , A. L. James1,2,5 , V. Papaioannou3 , S. L. Blaser4,5 , B. C. Papsin1,2,5
1Hospital For Sick Children, Archie's Cochlear Implant Laboratory, Toronto, Ontario Canada ; 2Hospital For
Sick Children, Otolaryngology Head And Neck Surgery, Toronto, Ontario Canada ; 3Hospital For Sick
Children, Department Of Communication Disorders, Toronto, Ontario Canada ; 4Hospital For Sick Children,
Division Of Pediatric Neuroradiology, Toronto, Ontario Canada ; 5University of Toronto, Department Of
Otolaryngology Head And Neck Surgery, Toronto, Ontario Canada
Topic: Surgery/Medical
Keywords: Radiology/Imaging , Medical/Surgical Issues
Objectives: We have previously examined and reported on the overlap between high resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in detecting abnormalities related to deafness in the precochlear implant pediatric population. This study led to a diagnostic algorithm that included routine MRI with selective HRCT based on risk factors. The current study aims to evaluate the efficacy of this diagnostic algorithm for the pre-operative assessment of children with profound sensorineural hearing loss (SNHL) prior to cochlear implantation (CI).
Methods: The radiologic imaging paradigm at our institution was retrospectively evaluated in all children undergoing evaluation for CI between January 2012 and June 2014 (n=152). During this time our evaluative protocol shifted to an MRI only paradigm with selective HRCT. This decision was made on the basis of cost and anesthesia time saving as well as reduction in radiation exposure and redundancy of imaging and these variables that will be evaluated in the current study.
Results: During the two and a half year period of the study, 152 children were evaluated for CI. MRI alone was performed in 145 cases while HRCT was performed subsequent to MRI in 3 cases due to the detection a small auditory nerve within the internal auditory canal. HRCT was preemptively ordered in conjunction with MRI in 4 cases due to specific risk factors including a known diagnosis of CHARGE Syndrome, history of meningitis and bilateral atresia. The MRI only paradigm allowed us to avoid radiation exposure in 145 children in addition to incurring a cost savings of over 50,000.00 US $ per annum and a significant reduction in wait times for imaging. The absence of HRCT imaging did not lead to additional surgical complications in this group.
ACI2014
Rapid High-Resolution Magnetic Resonance Imaging in Young Infants Without Sedation
J. A. Germiller, MD,Ph.D.1,3 , L. Bilaniuk2 , K. Kazahaya1,3
1Children's Hospital Of Philadelphia, Otolaryngology, Philadelphia, PA USA ; 2Children's Hospital Of
Philadelphia, Neuroradiology, Philadelphia, PA USA ; 3University Of Pennsylvania, Otolaryngology,
Philadelphia, PA USA
Topic: Surgery/Medical
Keywords: Radiology/Imaging , Medical/Surgical Issues
Introduction: High-resolution magnetic resonance imaging (MRI) has become widespread in the evaluation of pediatric cochlear implant candidates. It plays a critical role in the pre-operative evaluation, detecting inner ear malformations and cochlear nerve deficiency. Unfortunately, MRI protocols are lengthier than CT scan protocols, and thus, historically, MRI has required sedation in children. At our institution we have developed a rapid (approximately 7-minute), dedicated inner ear MRI protocol, which has allowed us to begin performing the procedure without sedation in young infants, during natural sleep. Objective: To describe our experience with unsedated, natural-sleep MRI for infants with sensorineural hearing loss (SNHL).
Methods: Patients who presented for evaluation of SNHL prior to 6 months of age, and who had minimal co-morbidities, were offered an attempt at an unsedated MRI using a 3D volumetric, T2-weighted, turbo spin-echo (TSE) MRI of the temporal bones under natural sleep. If infants remained asleep, then an additional 7-8 minute sequence (3D-CISS) was added. Medical and audiologic data, the success of the unsedated attempt, MRI diagnostic quality, scan time, and findings were reviewed.
Results: Fifteen infants underwent an attempt at unsedated MRI. Mean age at imaging was 3.3 months (range, 1-7 months). Twelve patients had bilateral SNHL, and 3 unilateral SNHL. Overall, 12 of the 15 (80%) infants were successfully scanned without sedation. Ten of the 12 bilateral patients (83%) were successful, and 2 of the 3 unilateral patients were successful. Scan times ranged from 6-10 minutes. Scan quality was excellent, and all scans were diagnostic. Findings were 9 with normal anatomy, and 1 each had bilateral enlarged vestibular aqueduct, bilateral incomplete partitioning, and unilateral cochlear nerve aplasia. All 12 infants slept well beyond their 7-minute protocol, in fact, remaining asleep at least 15 minutes. This allowed the technologist to perform the optional 7-8 minute CISS protocol in all cases. The 3 failures were due to infants waking up at the outset of the scanning. All 3 had significant hearing - one was unilateral, and the other 2 had bilateral moderate SNHL. All 3 were successfully re-imaged under sedation after 6 months of age.
Conclusion: High quality inner ear MRI, without sedation, is possible in young infants under 6
months. Short scan times are essential (< 15 minutes). Success is likely even in infants with unilateral or moderate hearing loss, but is somewhat more likely in bilateral profound deafness, likely because these infants are less likely to wake from the noise of the MRI scanner. Parents should be
counseled appropriately about success rates, and the possible need to re-schedule at a later date under sedation.
ACI2014
Predicting Depth of Electrode Insertion by Cochlear Measurements on CT Scans
S. I. Angeli, MD
1University Of Miami, Otolaryngology/School Of Medicine, Miami, FL USA
Topic: Surgery/Medical
Keywords: Medical/Surgical Issues , Radiology/Imaging
Introduction: A deep insertion of an electrode array into the apical segment of the cochlea is desirable for a maximal range of frequency stimulation. However, a deep insertion is not always possible. The Med-El cochlear implant system provides a test electrode to help electrode length selection: two separate insertions into the cochlea are required, one with the test electrode and a second one with the electrode array that matches the depth obtained with the test electrode. This double insertion may result in unnecessary trauma to the cochlea. The objective of this study is to predict depth of insertion by analysing the preoperative CT scan. Subjects: Adult and children who underwent cochlear implantation with a Med-El device in the period 2010-2014. Inclusion criteria included available preoperative high resolution CT scan. Subjects with labyrinthitis ossificans, cochlear hypoplasia or major inner ear malformations were excluded
Methods: Retrospective review of CT scans and operative reports. Several CT measurements of the cochlea were obtained. The insertion was considered deep when a full insertion of a Flex28 array was obtained, or when no more than one contact remained outside the cochlea when using a standard array. In contrast, an insertion was not considered deep when a medium length or a Flex24 array were used, or when more than one contact of a standard length or a Flex28 array remained outside the cochlea. Student’s T test was used to compare cochlear measurements between the groups of patients with and without deep insertion.
Results: Cochlear height measured on coronal views was associated with a deep insertion. Of 27 cases of deep insertion, the mean cochlear height was 6.26 mm (SD=0.8 mm). In contrast, the mean cochlear height of 8 cases without a deep insertion was 5.79 mm (SD=0.3 mm) (p=0.003).
Conclusion: Direct measurements of CT scans of the cochlea can predict the depth of insertion and help the selection of the appropriate electrode array preoperatively.
ACI2014
Safety And Imaging Quality Of MRI In Patients With Cochlear Implants Without Internal Magnet Removal
M. L. Carlson, MD1 , B. A. Neff1 , M. J. Link1 , J. I. Lane1 , R. E. Watson1 , C. L. Driscoll1
1Mayo Clinic, Rochester, MN USA
Topic: Surgery/Medical
Keywords: Medical/Surgical Issues, Radiology/Imaging
Introduction: The primary objective of the current study is to evaluate the safety and image quality of 1.5 Tesla MRI in patients with cochlear implants and retained internal magnets.
Methods: Retrospective case series at a tertiary academic referral center including all cochlear implant recipients who underwent 1.5 Tesla MRI without internal magnet removal, following application of a tight headwrap. Primary outcome measures included patient tolerance, complications, and characteristics of imaging artifact.
Results: Eighteen ears underwent a total of 31 MRI scans. One patient did not tolerate imaging with the headwrap in place and required magnet removal. One subject experienced 2 separate episodes of 180-degree magnet flipping requiring surgical repositioning under local anesthesia. Two patients were
discovered to have the magnet flipped 90-degrees after imaging, standing on end. In both cases the magnet could be reseated by applying gentle firm pressure to the scalp over the magnet. These two patients continue to use their device without difficulty and did not require surgical replacement. In patients receiving head MRI, the ipsilateral internal auditory canal and cerebellopontine angle could be visualized without difficulty in 91% of cases. There were no episodes of cochlear implant device failure or soft tissue complications.
Conclusion: 1.5 Tesla MRI is safe and well tolerated by most patients with cochlear implants. In nearly all cases, imaging artifact does not impede evaluation of the ipsilateral skull base. A small percentage of subjects may experience magnet displacement despite tight headwrap application. If a 180-degree flip of the internal magnet occurs, a trial of reversing the external magnet can be considered. In cases of partial displacement (such as standing on end), an attempt at reseating can be made by applying gentle firm pressure to the scalp over the internal magnet. If conservative measures fail, the magnet should be
surgically repositioned under local anesthesia to minimize interruption of device use and to prevent potential scalp complications.
ACI204
Comparison of Thinning vs Non-Thinning Techniques for Placement of Ponto Osseointegrated Auditory Implants in Children
K. W. Chang, MD1
1Stanford University, Otolaryngology, Palo Alto, CA USA
Topic: Other Implantable Devices
Keywords: Future of Implantable Devices
Introduction: The technique of placing osseointegrated auditory implants has gradually evolved over the years from significant alterations to the scalp flap with use of the dermatome, to a simpler linear incision with thinning, to minimal incision non-thinning techniques. Objective: To determine whether there are any significant advantages or drawbacks to the small-incision non-thinning technique for placing Ponto bone anchored implants in children.
Methods: Children between the ages of 6 and 12 (n=17) receiving Ponto osseointegrated auditory implants were retrospectively reviewed for indications, surgical results, and soft tissue complications.
Results: 7 cases were done with the small incision non-thinning technique and 10 cases with a more traditional linear incision with soft tissue thinning. The non-thinning technique resulted in fewer complications, better cosmetic appearance, as well as significantly reduced operative times.
Conclusion: The small-incision non-thinning single-stage technique has become our preferred method of placing osseointegrated auditory implants.
ACI2014
The Ideal Insertion Vector for Cochlear Implantation - Variations of a Theme
H. A. Breinbauer-Krebs, MA1,2,3 , P. K. Plinkert1 , M. J. Praetorius1
1University Of Heidelberg Medical Center, Dept. Of Otolaryngology, Div. Of Otology, Heidelberg, Germany ;
2Universidad De Chile, Servicio Otorrinolaringolog Santiago, Chile ; 3Clca Alemana De Santiago, Santiago,
Chile
Topic: Surgery/Medical
Keywords: Medical/Surgical Issues , Radiology/Imaging , Robotic Surgery, Computer Assisted Surgery
Introduction: Whereas through cochleostomy or round window approaches, the angle or vector of insertion after this first entry point appears to be related to intracochlear damage, which in turn may correlate with anatomical and functional results in cochlear implants.
Methods: Three dimensional reconstructions of temporal bones of 50 cochlear implant candidates (for a total of 100 ears) were assessed. The spatial orientation of an ideal insertion vector for both a cochleostomy and a round window approach were estimated.
Results: A difference as large as 60° was found between subjects for an ideal insertion vector. From an intraoperative perspective, this variability involves pushing the electrodes “as near from the buttress” or “as near from the emergence of the corda tympani” as possible, depending on the case.
Conclusion: The orientation of the basal turn, and the corresponding ideal electrode insertion vector, varies largely among subjects. A proper pre-operative estimation on a case to case scenario for this feature may lead to technique adaptation during insertion, which may contribute to minimizing electrode insertion trauma and eventually optimizing anatomical and functional results.
ACI2014
Delivering Audible Signal to the Surgeon in Image-Guided Otologic Surgery
N. Matsumoto, MD,Ph.D.1 , B. Cho, Ph.D.2 , M. Hashizume, MD,Ph.D.2 , S. Komune, MD,Ph.D.1
1Kyushu University, Dept. Of Otorhinolaryngology, Fukuoka, Fukuoka Japan ; 2Kyushu University, Dept. Of
Advanced Medical Initiatives, Fukuoka, Fukuoka Japan
Topic: Surgery/Medical
Keywords: Robotic Surgery, Computer Assisted Surgery
Introduction: Image-guided surgery (IGS) system locates a surgical tool and projects its position onto the patient’s radiographic image. Conventional IGS provides visual information on the computer screen. Therefore, the surgeon in the otologic surgery must switch his/her focus between the microscope and the computer screen to identify the position of the drill, causing temporary interruptions of the drilling procedure especially when the drill is near a critical structure. To solve this problem, a system that warns the surgeon by audible signals was developed to deliver image-guided information without distracting the surgeon from the surgical microscope.
Methods: We developed and integrated a safe drilling distance alarm module into an otological
IGS navigation system based on a free open source software platform (3D Slicer). The coordinates of the three safe regions were segmented preoperatively for the facial nerve and the cochlea. Each safe region had safety margin of 2, 4, or 6 mm from the facial nerve or the cochlea. In the operating room, the closest distance between the drill tip and the surface of the facial nerve or the cochlea was continuously monitored. When the drill tip entered any of the safe regions, the navigation system generated auditory signals that differed in each safe region. Specifically, the computer generated 300 Hz tone when the drill entered the 6 mm region, 600 Hz tone when the drill entered the 4 mm region, and 900 Hz tone when the drill entered the 2 mm region. Visual information was also provided on the computer screen, with more details including the absolute values of the distance to the facial nerve or the cochlea. To evaluate the effectiveness of the system, a resident in training performed phantom experiments for maintaining a 2-mm safe margin from the facial nerve when drilling bone models, with and without the navigation system. The error of the safe margin was measured on postoperative CT images. In real surgery, we evaluated the feasibility of the system in comparison with conventional facial nerve monitoring.
Results: The navigation accuracy measured as the target registration error was submillimeter. In the phantom study, the resident successfully accomplished the task with smaller chance of facial nerve injury when our proposed system was used. The clinical feasibility of the system was confirmed in three cochlear implantations.
Conclusion: The IGS system that can deliver information to the surgeon with audible signals could assist surgeons without interrupting the microscopic procedure. This system would solve the common difficulty with image-guided otologic surgery that the otologist must focus both on the microscope and the image-guidance information when drilling near a critical structure.
Session 4: Electrode and Device Considerations
ACI2014
Hearing Preservation After Partial Deafness Cochlear Implantation with Different Electrodes in Children
with Substantial Residual Hearing
P. H. Skarzynski, MD,Ph.D.1,2,3 , A. Lorens, MS,Ph.D.1 , A. Walkowiak, MS1 , M. Matusiak, MD,Ph.D.1 , H. Skarzynski, MD,Ph.D.,Prof.1
1Institute Of Physiology And Pathology Of Hearing, World Hearing Center, Warsaw, MAZOWIECKIE
Poland;2Medical University Of Warsaw, Warsaw, MAZOWIECKIE Poland ; 3Institute Of Sensory Organs,
Kajetany, MAZOWIECKIE Poland
Topic: Audiology
Keywords: Residual Hearing
Introduction: Low frequencies are crucial for fine time structure information delivery, which is especially important for appropriate language development in children, but also for music perception and
intonation. Objective: Cochlear implantation aiming preservation of low frequency residual hearing requires special atraumatic approach. 6 steps surgical procedure for partial deafness treatment was designed and applied for this purpose being applicable in adults as well as in children.
Methods: 219 children with audiometric criteria for low frequency hearing threshold (EC- 500Hz < 30dB) underwent cochlear implantation with Nucleus CI422, Flex electrodes from MEDEL cochlear implant. Minimal invasive surgical procedure with round window approach for partial deafness treatment was applied in every case. In all implanted patients steroids were administered peri-operatively and up to 14th day after implantation
Results: By understanding preservation of hearing as the elevation of hearing threshold in tonal audiometry no greater than 10dB - in 91% of implanted cases substantial preoperative hearing was preserved in low and middle frequencies postoperatively. Over 36 months of follow up thresholds were estimated as stable within given conditions in 87% of cases. Speech audiometry tests showed significant improvement of performance both in AAST and SA.
Conclusion: Straight and flexible electrodes are proved to be a good solution for cochlear implantation aiming preservation of hearing in low frequencies. Partial deafness cochlear implantation surgery in children gives possibility for successful preservation of low frequency hearing, and combined electric - acoustic stimulation. Pre-operative assessment is indispensable.
ACI2014
Impact of Placing a Modiolar Hugging Array and Slim Straight Array in Opposite Ears of the Same Pediatric Patient
L. R. Park,Au.D.1 , J. Roche1 , H. F. Teagle,Au.D.1 , J. Woodard,Au.D.1 , E. Gagnon,Au.D.1 , C. Buchman1
1University Of North Carolina At Chapel Hill, Otolaryngology/Head And Neck Surgery, Chapel Hill, NC USA
Topic: Audiology
Keywords: Binaural Hearing , Outcomes , Residual Hearing
Introduction: There is an increasing interest in preserving residual hearing during cochlear
implantation. The ever evolving landscape of cochlear implants presents the possibility of inserting a hearing preservation electrode when a child has already received a contour electrode in the opposite ear during an earlier surgery. Differing electrode arrays in the same patient may present challenges in terms of programming, sound quality, speech understanding, and even battery life. It is important to investigate outcomes in these patients to determine the feasibility of such interventions. The purpose of this study was to examine differences and similarities in outcomes between the ears of bilaterally implanted children who received modiolar hugging and slim straight arrays in opposite ears.
Methods: Outcome data were analyzed for 10 children who received a modiolar hugging array in one ear and a slim straight array in another ear in sequential surgeries. Data were collected regarding differences in word recognition, impedance changes, surgical differences, preservation of residual hearing, battery life, electrical compound action potential thresholds at and post-surgery, electrical threshold charge level, and comfort charge level.
Results: While there were differences between ears and variability among subjects, none of the differences were substantial enough to impact everyday use and performance with bilateral cochlear implants.
Conclusion: Sequential cochlear implant surgery with placement of modiolar and slim straight arrays in opposite ears is a viable intervention for pediatric bilateral cochlear implant candidates.
ACI2014
Surgical Survey on the Usability and Applicability of the HiFocus Mid-Scala Electrode
M. L. Bush, MD1, M. Adkins,AuD1 , E. Bero,AuD2 , D. Gazibegovic3
1University Of Kentucky, Department Of Otolaryngology - Head And Neck Surgery, Lexington, KY USA;
2Advanced Bionics LLC, Valencia, CA USA; 3Advanced Bionics AG, STĆA, MEILEN Switzerland
Topic: Surgery/Medical
Keywords: Medical/Surgical Issues , Hearing Preservation
Introduction: Soft surgical techniques are designed to minimize damage to delicate cochlear structures during cochlear implantation. Location and technique of electrode insertion play a vital role in hearing preservation. With developments in electrode design, there has been resurgence of round window electrode insertion. However, the unfavorable anatomy and orientation of the round window may complicate
atraumatic electrode insertion. Additionally, the location of the electrode within the cochlea may play a role in long-term hearing preservation. The HiFocus Mid-Scala electrode has been designed to (1) to provide optimal placement within the cochlea to minimize trauma to the modiolus and the lateral wall structures and (2) to give surgical flexibility in the location and method of electrode insertion. Objective: An
electronic surgical survey was designed to capture information regarding use of the mid-scala electrode and insertion tools by a large group of surgeons for a broad population of cochlear implant recipients of differing ages. The data provide understanding regarding flexibility of the electrode and insertion tools to support differing surgical techniques based on anatomical factors. The data also indicate the type and frequency of surgical techniques applicable with the electrode, and provide selection, acceptance, and use preferences from cochlear implant surgeons.
Methods: The survey is being conducted in multiple implant centers in Europe, North America, and Asia. Three questionnaires are used: the first collects data on surgeon experience and electrode preferences; the second provides data about electrode insertions for specific individual surgical cases; and a third final survey summarizes overall surgeon experience with the mid-scala array across a number of surgical cases. Audiologic outcomes from mid-scala recipients from one implant center were analyzed.
Results: Data from 23 surgeons representing 13 implant centers and over 100 surgeries have been collected. Regarding cochlear implant position, the majority of participating surgeons preferred mid-scalar location (65%) over lateral wall (4%), perimodiolar (4%), or variable location (26%). The round window (43.4%) was the preferred insertion location compared with cochleostomy and extended round window and the majority of surgeons preferred free-hand insertion (83%) over the use of insertion tools. The ability to use soft surgical techniques was the most reported reason for using the HiFocus mid-scala
electrode. Minimal deviations from preferred insertion location and technique were reported by surgeons. Case reports with associated audiologic outcomes for mid-scala recipients will be reported.
Conclusion: The mid-scala electrode design effectively supports surgeon preferences for soft-surgery techniques, including round window insertions. The electrode also allows for flexibility in surgical technique depending upon individual patient anatomical constraints.
ACI2014
Electrode and Access Variables in Cochlear Implantation
S. McMenomey1 , J. Roland1 , D. Friedmann1 , L. Zhao1
1New York University School Of Medicine, Otolaryngology, New York, NY USA
Topic: Surgery/Medical
Keywords: Medical/Surgical Issues , Hearing Preservation
Introduction: Numerous published manuscripts detail results of studies related to electrode characteristics and cochlear access. There is no consistent data that provides absolute evidence that one approach (cochleostomy vs round window) or one electrode type is superior to all others. This presentation will outline the current published work on the subject and provide observations from our electrode research laboratory.
Methods: A literature review on the subject will be presented. Additionally, recent studies from our laboratory of electrode insertion dynamics, electrode insertion forces on the cochlear walls and histologic analysis post insertion will be presented. Straight and coiling perimodiolar electrodes were reviewed.
Results: Cochlear access is a variable, as are electrode type and insertion forces, in intracochlear position and intracochlear trauma. Additionally, the angle of electrode insertion, with relation to the basal turn of the cochlea, affects results. Discussion: Angle of insertion, insertion speed, insertion technique, cochlear access and electrode type affect outcomes.
Conclusion: Attention to the variables studied in this report is essential for optimal cochlear implant electrode insertion and outcomes. There are many ways to provide patients with an implant that will provide enhanced auditory performance. By understanding the details of each electrode design, insertion technique and cochlear access, one can provide the best outcomes.
ACI2014
Stimulating Multiple Electrodes Improves Rate Pitch Perception for Cochlear Implant Users
R. T. Penninger1,2 , E. Kludt1,2 , W. Nogueira1,2 , A. Buechner1,2
1Medical University Hannover, Department Of Otolaryngology, Hannover, 30625 Germany ; 2Cluster Of
Excellence "Hearing4all", Hannover, 30625 Germany
Topic: Technology
Keywords: Cochlear Implant Hardware , Sound Coding , Speech Coding Strategies
Introduction: The coding of pitch in modern cochlear implant devices is challenging for recipients as it is mainly based on place pitch, which is subject to the location of a finite number of electrodes on an array. The coding of pitch via temporal cues in the stimulation may help to improve pitch perception since most cochlear implant subjects are able to perceive rate changes on a single electrode up to around 300 Hz. Some optimally performing subjects are able to perceive temporal pitch up to 1000 Hz. However,
performance varies highly between subjects and depends on the selected electrodes. The objective of this study was to test if stimulating multiple electrodes with temporal pitch improves pitch ranking performance.
Methods: 10 cochlear implant subjects were asked to pitch rank stimuli presented with direct electrical stimulation. The pulses were presented on one, three, six or eleven electrodes. Their frequency ranged from 100 up to 500pps. In one of the conditions the current amplitude of each pulse was randomly varied
between 0 and 100%.
Results: Listeners show the “classic” performance pattern in most presentation modes with very good performance at the lowest standard rates and deteriorating performance to near chance level at the highest rate tested. Performance with eleven electrodes was overall significantly better than performance with one or three electrodes.
Conclusion: Improving temporal pitch perception by stimulating multiple electrodes might be an important factor to better understanding of the mechanisms behind temporal pitch perception and it could lead to improved language and music perception.
ACI2014
Hearing Outcomes Among Children with a Slim Perimodiolar Electrode Array
D. P. Sladen, Ph.D. , M. DeJong,Au.D.1 , A. Breneman,Au.D.1 , L. Belf,Au.D1 , A. Olund,Au.D.1 , C. Beatty, MD1 ,
A. Peterson, MA1 , B. Neff, MD1 , C. Driscoll, MD1
1Mayo Clinic, Rochester, MN USA
Topic: Audiology
Keywords: Outcomes, Residual Hearing
Introduction: Hearing preservation is a desirable outcome after pediatric cochlear implant surgery. If maintained, postoperative hearing allows access to electroacoustic stimulation (EAS). Though not fully explored in children, EAS among adult patients improves speech in noise understanding, music enjoyment and localization. Objective:: The aim of this study was to determine the rate of hearing preservation among children implanted with a thin, perimodiolar electrode array. If hearing was preserved, was it also functional such that a hearing aid or EAS could be used on the ipsilateral side of implantation?
Methods: This quasi-retrospective analysis of children implanted with a thin peri modiolar electrode array included 15 children implanted between 2012 and 2013. Behavioral hearing thresholds for frequencies between 125 and 1500 Hz were captured preoperatively, and 3-months post-operatively.
Results: To date, 40% of the children have been tested. Of this subgroup, all had less than a 15 dB shift in hearing levels, and all had functional hearing for use of EAS. Data collection is ongoing.
Conclusion: Preliminary results suggest that hearing preservation is possible among pediatric patients. Data collection is ongoing and will be discussed in detail.
ACI2014
Impact of Electrode Design and Surgical Approach on Scalar Location and Outcomes in Cochlear Implantation
G. B. Wanna, MD,FACS1 , J. H. Noble, Ph.D.1 , M. L. Carlson, MD1 , R. H. Gifford, Ph.D.1 , M. S. Dietrich, Ph.D.1 , D. S. Haynes, MD,FACS1 , B. M. Dawant, Ph.D.1 , R. F. Labadie, MD,FACS,Ph.D.1
1Vanderbilt University Medical Center, Otology-Neurotology, Nashville, TN USA
Topic: Surgery/Medical
Keywords: Robotic Surgery, Computer Assisted Surgery , Hearing Preservation , Radiology/Imaging
Introduction: Three surgical approaches: cochleostomy (C), round window (RW), and extended round window (ERW); and two electrodes types: lateral wall (LW) and perimodiolar (PM), account for the vast majority of cochlear implantations. The goal of this study was to analyze the relationship between surgical approach and electrode type with final intracochlear position of the electrode array and subsequent hearing outcomes
Methods: One hundred postlingually implanted adult patients were enrolled in the study. From the postoperative scan, intracochlear electrode location was determined and using rigid registration, transformed back to the preoperative computed tomography which had intracochlear anatomy (scala tympani and scala vestibuli) specified using a statistical shape model based on 10 microCT scans of human cadaveric cochleae. Likelihood ratio chi-square statistics were used to evaluate for differences in electrode placement with respect to surgical approach (C, RW, ERW) and type of electrode (LW, PM).
Results: Electrode placement completely within the scala tympani (ST) was more common for LW than were PM designs (89% vs. 58%; P < 0.001). RW and ERW approaches were associated with lower rates of electrode placement outside the ST than was the cochleostomy approach (9%, 16%, and 63%, respectively; P < 0.001). This pattern held true regardless of whether the implant was LW or PM. When examining electrode placement and hearing outcome, those with electrode residing completely within the ST had better consonant-nucleus-consonant word scores than did patients with any number of electrodes located outside the ST (P = 0.045).
Conclusion: These data suggest that RW and ERW approaches and LW electrodes are associated with an increased likelihood of successful ST placement. Furthermore, electrode position entirely within the ST confers superior audiological outcomes.
