Gene Electrotransfer via Conductivity-Clamped Electric Field Focusing Pivots Sensori-Motor DNA Therapeutics: "A Spoonful of Sugar Helps the Medicine Go Down".

Viral vectors and lipofection-based gene therapies have dispersion-dependent transduction/transfection profiles that thwart precise targeting. The study describes the development of focused close-field gene electrotransfer (GET) technology, refining spatial control of gene expression. Integration of fluidics for precise delivery of "naked" plasmid deoxyribonucleic acid (DNA) in sucrose carrier within the focused electric field enables negative biasing of near-field conductivity ("conductivity-clamping"-CC), increasing the efficiency of plasma membrane molecular translocation. This enables titratable gene delivery with unprecedently low charge transfer. The clinic-ready bionics-derived CC-GET device achieved neurotrophin-encoding miniplasmid DNA delivery to the cochlea to promote auditory nerve regeneration; validated in deafened guinea pig and cat models, leading to improved central auditory tuning with bionics-based hearing. The performance of CC-GET is evaluated in the brain, an organ problematic for pulsed electric field-based plasmid DNA delivery, due to high required currents causing Joule-heating and damaging electroporation. Here CC-GET enables safe precision targeting of gene expression. In the guinea pig, reporter expression is enabled in physiologically critical brainstem regions, and in the striatum (globus pallidus region) delivery of a red-shifted channelrhodopsin and a genetically-encoded Ca2+ sensor, achieved photoactivated neuromodulation relevant to the treatment of Parkinson's Disease and other focal brain disorders.

Innominate Artery Pseudoaneurysm Requiring Cartilage Tracheal Repair in a Child.

Mycotic aneurysms are rare but potentially catastrophic. We report a case of an innominate artery pseudoaneurysm in a 4-year-old patient that caused a tracheoinnominate fistula requiring tracheoplasty with a costal cartilage graft and a homograft iliac artery replacement of the diseased innominate artery, with a successful outcome.

Clinical performance, safety, and patient-reported outcomes of an active osseointegrated bone-conduction hearing implant system at 24-month follow-up.

PURPOSE: To investigate 2-year post-operative hearing performance, safety, and patient-reported outcomes of hearing-impaired adults treated with the Osia® 2 System, an active osseointegrated bone-conduction hearing implant that uses piezoelectric technology. METHODS: A prospective, multicenter, open-label, single-arm, within-subject clinical study conducted at three tertiary referral clinical centers located in Melbourne, Sydney and Hong Kong. Twenty adult recipients of the Osia 2 System were enrolled and followed up between 12 and 24 months post-implantation: 17 with mixed or conductive hearing loss and 3 with single-sided sensorineural deafness. Safety data, audiological thresholds, speech recognition thresholds in noise, and patient-reported outcomes were collected and evaluated. In addition, pre-and 6-month post-implantation data were collected retrospectively for this recipient cohort enrolled into the earlier study (ClinicalTrials.gov NCT04041700). RESULTS: Between 6- and 24-month follow-up, there was no statistically significant change in free-field hearing thresholds or speech reception thresholds in noise (p = > 0.05), indicating that aided improvements were maintained up to 24 months of follow-up. Furthermore, improvements in health-related quality of life and daily hearing ability, as well as clinical and subjective measures of hearing benefit remained stable over the 24-month period. No serious adverse events were reported during extended follow-up. CONCLUSIONS: These study results provide further evidence to support the longer term clinical safety, hearing performance, and patient-related benefits of the Osia 2 System in patients with either a conductive hearing loss, mixed hearing loss, or single-sided sensorineural deafness. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04754477. First posted: February 15, 2021.

Post Cochlear Implantation Vertigo: Ictal Nystagmus and Audiovestibular Test Characteristics.

OBJECTIVE: To investigate ictal nystagmus and audiovestibular characteristics in episodic spontaneous vertigo after cochlear implantation (CI). STUDY DESIGN: Retrospective and prospective case series. PATIENTS: Twenty-one CI patients with episodic spontaneous vertigo after implantation were recruited. INTERVENTIONS: Patient-initiated home video-oculography recordings were performed during one or more attacks of vertigo, using miniature portable home video-glasses. To assess canal and otolith function, video head-impulse tests (vHITs) and vestibular-evoked myogenic potential tests were conducted. MAIN OUTCOME MEASURES: Nystagmus slow-phase velocities (SPVs), the presence of horizontal direction-changing nystagmus, and post-CI audiovestibular tests. RESULTS: Main final diagnoses were post-CI secondary endolymphatic hydrops (48%) and exacerbation of existing Ménière's disease (29%). Symptomatic patients demonstrated high-velocity horizontal ictal-nystagmus (SPV, 44.2°/s and 68.2°/s in post-CI secondary endolymphatic hydrop and Ménière's disease). Direction-changing nystagmus was observed in 80 and 75%. Two were diagnosed with presumed autoimmune inner ear disease (SPV, 6.6°/s and 172.9°/s). One patient was diagnosed with probable vestibular migraine (15.1°/s).VHIT gains were 0.80 ± 0.20 (lateral), 0.70 ± 0.17 (anterior), and 0.62 ± 0.27 (posterior) in the implanted ear, with abnormal values in 33, 35, and 35% of each canal. Bone-conducted cervical and ocular vestibular-evoked myogenic potentials were asymmetric in 52 and 29% of patients (all lateralized to the implanted ear) with mean asymmetry ratios of 51.2 and 35.7%. Reversible reduction in vHIT gain was recorded in three acutely symptomatic patients. CONCLUSION: High-velocity, direction-changing nystagmus time-locked with vertigo attacks may be observed in post-CI implant vertigo and may indicate endolymphatic hydrops. Fluctuating vHIT gain may be an additional marker of a recurrent peripheral vestibulopathy.

Cochlear Implant Adult Speech Perception Outcomes: Seniors Have Similar Good Outcomes.

OBJECTIVE: The primary aim was to analyze the speech perception outcomes of patients with cochlear implants 65 years and older, compared with those younger than 65 years. The secondary aim was to analyze if preoperative hearing levels, severe compared with profound, had an effect on speech perception outcomes in senior citizens. STUDY DESIGN: Retrospective case review of 785 patients, between 2009 and 2016. SETTING: A large cochlear implant program. PATIENTS: Cochlear implant adult recipients younger than 65 years and 65 years and older at the time of surgery. INTERVENTIONS: Therapeutic-cochlear implant. MAIN OUTCOME MEASURES: Speech perception outcomes, using City University of New York (CUNY) sentences and Consonant-Nucleus-Consonant (CNC) words. Outcomes were measured preoperatively and postoperatively at 3, 6and 12 months for cohorts younger than 65 years and 65 years and older. RESULTS: Adult recipients younger than 65 years compared with those 65 years and older had comparable outcomes for CUNY sentence scores outcomes ( p = 0.11) and CNC word scores ( p = 0.69). The preoperative four-frequency average severe hearing loss (HL) cohort was significantly better compared with the profound HL cohort, for both the CUNY sentence scores ( p < 0.001) and CNC word scores ( p < 0.0001). The four-frequency average severe HL cohort had better outcomes irrespective of age. CONCLUSIONS: Senior citizens have similarly good speech perception outcomes as adults younger than 65 years. Those with preoperative severe HL have better outcomes than profound loss. These finds are reassuring and can be used when counseling older cochlear implant candidates.

Distance and Socieoeconomic Status as Barriers to Cochlear Implantation.

OBJECTIVE: To assess the distance burden for access to cochlear implant (CI)-related services and to assess whether socioeconomic disadvantage or level of education and occupation influenced uptake of CIs. STUDY DESIGN: Retrospective case review. SETTING: A CI services provider operating across multiple centers. PATIENTS: All patients undergoing CI surgery in a 2-year period between March 2018 and February 2020. INTERVENTIONS: Diagnosis of hearing loss, CI surgery, and subsequent habilitation and mapping. MAIN OUTCOME MEASURES: Distance traveled by patients to their audiological diagnostic, CI surgery hospital, and habilitation sites; subjects' index of relative socioeconomic advantage and disadvantage (IRSAD) and index of education and occupation (IEO). RESULTS: n = 201 children and n = 623 adults. There was a significant difference across IRSAD domains for children (p < 0.0001) and adults (p < 0.0001), and IEO in children (p = 0.015) and adults (p < 0.0001) when tested for equal proportions. The median driving distance from home to the diagnostic audiological site for children was 20 km (mean, 69 km; range, 1-1184 km; upper quartile, 79 km; lower quartile, 8 km). There was no significant difference between the driving distances from home to the CI surgery hospital site, or the mapping/habilitation sites between children and adults. There was no correlation for age at first surgery and either IRSAD/IEO. CONCLUSIONS: The burden of distance for access to CI in Australia is significant for the upper quartile who may not live within the large city centers. Greater consideration needs to be given regarding barriers to CI for those in lower socioeconomic and educational groups to ensure equity of access across different socioeconomic and educational level backgrounds.

Management of Recurrent and Delayed Post-Tonsillectomy and Adenoidectomy Hemorrhage in Children.

OBJECTIVE: To review our experience on post-tonsillectomy and/or adenoidectomy hemorrhage (PTAH) at a tertiary pediatric referral hospital and to evaluate the management and risk factors for recurrent postoperative hemorrhage and for delayed bleeding after day 14. METHODS: A retrospective chart review was performed for all pediatric patients admitted to The Children's Hospital at Westmead for PTAH between July 01, 2014, and June 30, 2019. Patients with recurrent hemorrhage and those with bleeding after day 14 were selected for subanalysis. RESULTS: Of the 291 patients admitted for PTAH, 31 (11%) patients had recurrent postoperative hemorrhage, and 11 (4%) patients had delayed bleeding after day 14. Surgical intervention for cessation of hemorrhage was required in 88 (30%) patients, including 2 patients who required return to the theater more than once. Nine (3%) patients received blood transfusions. The average number of days between bleeding episodes was 4 days. Recurrent postoperative hemorrhage occurred in 8.5% of patients who were managed operatively at their first presentation compared to 11.4% of patients who were managed nonoperatively (odds ratio: 1.1; 95% confidence interval 0.43-2.8). No association was found between abnormal coagulation profile, surgical indication, and risk of delayed postoperative hemorrhage. CONCLUSIONS: Recurrent or delayed postoperative hemorrhage represents a small proportion of children with postoperative bleeding and cannot be reliably predicted. Management of first presentations with either a conservative or a surgical approach is reasonable since the risk of recurrent of PTAH may be unrelated to the choice of management at initial presentation. Careful preoperative counseling of patients and their families is important to help set expectations in the event of PTAH.

Clinical Performance, Safety, and Patient-Reported Outcomes of an Active Osseointegrated Steady-State Implant System.

OBJECTIVE: To investigate the clinical performance, safety, and patient-reported outcomes of an active osseointegrated steady-state implant system that uses piezoelectric technology. STUDY DESIGN: A prospective, multicenter, open-label, single-arm, within-subject clinical investigation. SETTING: Three tertiary referral clinical centers located in Melbourne, Sydney, and Hong Kong. PATIENTS: Twenty-nine adult subjects, 24 with mixed hearing loss or conductive hearing loss and 5 with single-sided sensorineural deafness. INTERVENTION: Implantation with the Cochlear Osia 2 System. MAIN OUTCOME MEASURES: Audiological threshold evaluation and speech recognition in quiet and in noise. Patient satisfaction and safety. RESULTS: At 6-month follow-up after surgery, a mean improvement in pure-tone average of 26.0 dB hearing level and a mean improvement of 8.8 dB signal-to-noise ratio in speech reception threshold in noise was achieved with the investigational device as compared with the unaided situation. Usability of the investigational device was rated 71.4/100 mm for sound processor retention and 81.4/100 mm for overall comfort using a visual analog scale. CONCLUSION: These outcomes confirm the clinical safety, performance, and benefit of an innovative active transcutaneous bone conduction implant using a piezoelectric transducer design in subjects with conductive hearing loss, mixed hearing loss, or single-sided sensorineural deafness.

Misplaced Cochlear Implant Electrodes Outside the Cochlea: A Literature Review and Presentation of Radiological and Electrophysiological Findings.

HYPOTHESIS: It is possible to detect when misplacement and malposition of the cochlear implant (CI) electrode array has occurred intraoperatively through different investigations. We aim to explore the literature surrounding cochlear implant misplacements and share our personal experience with such cases to formulate a quick-reference guide that may be able to help cochlear implant teams detect misplacements early. BACKGROUND: Misplacement and malposition of a cochlear implant array can lead to poor hearing outcomes. Where misplacements go undetected during the primary surgery, patients may undergo further surgery to replace the implant array into the correct intracochlear position. METHODS: Systematic literature review on cochlear implant misplacements and malpositions and a retrospective review of our program's cases in over 6,000 CI procedures. RESULTS: Twenty-nine cases of CI misplacements are reported in the English literature. Sixteen cases of cochlear implant misplacements are reported from our institution with a rate of 0.28%. A further 12 cases of intracochlear malpositions are presented. The electrophysiological (CI electrically evoked auditory brainstem response, transimpedance matrix) and radiological (X-ray and computed tomography scan) findings from our experience are displayed in a tabulated quick-reference guide to show the possible characteristics of misplaced and malpositioned cochlear implant electrode arrays. CONCLUSION: Both intraoperative electrophysiological and radiological tests can show when the array has been misplaced or if there is an intracochlear malposition, to prompt timely intra-operative reinsertion to yield better outcomes for patients.

To Use the Back-up Cochlear Implant or Not? Using Intra-operative Impedance to Guide Your Decisions.

INTRODUCTION: Intra-operative electrophysiological testing is being increasingly used to determine device functionality. Impedance abnormalities (open or short circuits) measured at time of surgery pose a dilemma: is it likely to resolve or is it a permanent fault? There is little in the literature on how to manage these intraoperative finding and if, at time of surgery, the back-up device should be used. METHODS: We routinely undertake impedance testing twice intraoperatively, as well as at switch on, 1 and 3 months postoperatively. Retrospective impedance thresholds were analysed for one surgeon's cases between January 2018 and December 2019. RESULTS: There were 235 cochlear implants performed for 217 patients (5,020 electrode contacts) analysed. Thirty-three electrodes had abnormal impedance thresholds on first intraoperative cycle of testing, 76% resolving with the second testing cycle electrode contacts that demonstrated abnormal impedance during both intraoperative test cycles were 16.54 times (95%CI 2.55-107.13, p = 0.003) more likely to be abnormal at three months. Fifty percent resolved by switch on. The intraoperative abnormalities made up 26% of electrode abnormalities seen at 3 months postoperatively. DISCUSSION: This study demonstrates the utility of 2 cycles of intraoperative impedance testing, with persistently abnormal electrodes having 16 times the likelihood of persistent abnormalities of impedance, and 50% resolution. These persistent intra-operative abnormal electrodes are responsibly for 26% of electrode abnormalities at 3 months. This information is useful for the surgeon when considering use of the backup cochlear implant device.

Impact of Cochlear Implantation on Canal and Otolith Function.

OBJECTIVE: To quantify the impact of cochlear implantation (CI) on all five vestibular end-organs and on subjective ratings of post-CI dizziness. METHODS: Seventy-two patients undergoing unilateral CI were recruited for the study. All participants completed pre- and post-CI three-dimensional video head-impulse tests (3D vHITs) to assess semicircular-canal (SC) function, air- and bone-conducted (AC and BC) cervical and ocular vestibular-evoked myogenic potentials (cVEMPs and oVEMPs) to assess otolith-function and the dizziness handicap inventory (DHI) to measure self-perceived disability. RESULTS: Nineteen percent of patients reported new or worsened dizziness postsurgery. Post-CI abnormalities (new lesions and significant deteriorations) were seen in the AC cVEMP (48%), AC oVEMP (34%), BC cVEMP (10%), and BC oVEMP (7%); and lateral (L) (17%), posterior (P) (10%), and anterior (A) (13%) SC vHITs. CI surgery was more likely to affect the AC cVEMP compared with the other tests (χ2 test, p < 0.05). Fifty percent of patients reported no dizziness pre- and postsurgery. In the implanted ear, normal pre-CI vHIT gain was preserved in lateral semicircular canal (LSC) (69%), anterior semicircular canal (ASC) (74%), and posterior semicircular canal (PSC) (67%), and normal reflex amplitudes were found in AC cVEMP (25%), AC oVEMP (20%), BC cVEMP (59%), and BC oVEMP (74%). Statistically significant decreases were observed in LSC vHIT gain, AC cVEMP amplitude, and AC oVEMP amplitude postsurgery (p < 0.05). There was a significant moderate positive correlation between change in DHI scores and the summed vestibular deficit postsurgery (r(51) = 0.38, p < 0.05). CONCLUSION: CI can impact tests that assess all five vestibular end-organs and subjective ratings of dizziness. These results support pre and post-surgical vestibular testing and assist preoperative counseling and candidate selection.

Ear Abnormalities Among Children with Fetal Alcohol Spectrum Disorder: A Systematic Review and Meta-Analysis.

OBJECTIVE: To systematically review and conduct meta-analysis on studies that report the type and prevalence of functional and structural ear abnormalities among children with prenatal alcohol exposure and/or fetal alcohol spectrum disorder (FASD). STUDY DESIGN: MEDLINE, PubMed, Embase, Web of Science, PsycINFO, ERIC, CINAHL, and Maternity and Infant Care were searched from 1806 through March 2021. Reference lists of relevant articles were manually searched. Studies reporting on functional and/or structural ear abnormalities among children (<18 years) with prenatal alcohol exposure and/or FASD were eligible. Data extraction and quality assessment were performed by one reviewer and independently checked by another. A random effects meta-analysis was conducted. RESULTS: A total of 31 studies met the inclusion criteria and 25 were included in the meta-analyses, representing a total of 843 children with prenatal alcohol exposure and 1653 children with FASD. Functional ear abnormalities with the highest pooled prevalence were chronic serous otitis media (88.5%; 95% CI, 70.4%-99.3%), abnormal auditory filtering (80.1%; 95% CI, 76.5%-84.3%), and unspecified conductive hearing loss (68.0%; 95% CI, 51.9%-82.2%). Structural ear abnormalities with the highest pooled prevalence were microtia (42.9%; 95% CI, 26.8%-59.7%), railroad track ear (16.8%; 95% CI, 8.1%-27.7%), and misplaced ear (12.3%; 95% CI, 7.6%-17.9%). CONCLUSIONS: Our findings highlight the importance of examining the ears during assessment for FASD, and the need for public health messaging regarding the harms of prenatal alcohol exposure.

Intraoperative Cochlear Implant Reinsertion Effects Evaluated by Electrode Impedance.

OBJECTIVES: To assess the effect on impedance levels of intraoperative reinsertion of a cochlear implant (CI) array compared with matched controls. STUDY DESIGN: Retrospective patient review. SETTING: Cochlear implant center. PATIENTS: CI recipients in the Sydney Cochlear Implant Centre (SCIC) database who required intraoperative array reinsertion and matched controls. Exclusion criteria; known preceding meningitis or labyrinthitis ossificans; electrode array buckling; incomplete "final" insertion. INTERVENTION: Cochlear implantation. MAIN OUTCOME MEASURES: Impedance values measured intraoperatively, at switch on, 3 months, 6 months, and 12 months postoperatively were analyzed. The Generalized Estimating Equation (GEE) Model was used to compare cases with controls for each device, at each time point, and for each channel. RESULTS: Thirty-one reinsertion cases identified; six CI 422 arrays; 14 CI 24RE (ST) arrays, and 11 CI 512 arrays. No increase in impedance levels was found in the reinsertion cases when compared with their matched controls. The only statistical difference in impedance was seen in the CI 422 cohort at switch on with the reinsertion cases having lower impedances (p = 0.03). CONCLUSION: This is the first study to examine impedance values in patients who underwent intraoperative CI array reinsertion and to compare them with the impedances of matched controls. No significant increase found in impedances between our reinsertion cases and matched controls, suggesting the reinsertion did not result in any additional trauma or inflammation. This has implications for surgery both in routine cases such as a faulty electrode and also for future design of mechanisms for delivery of intracochlear therapies.

Comparison of electrode impedance measures between a dexamethasone-eluting and standard Cochlear™ Contour Advance® electrode in adult cochlear implant recipients.

OBJECTIVE: To compare the difference in electrode impedance across discrete time points to 24 months post-activation for two groups of adult cochlear implant recipients, one using an investigational perimodiolar (Contour Advance®) array augmented with 40% concentration weight per weight (w/w) dexamethasone (the Drug Eluting Electrode, 'DEE' Group), and the other the commercially available Contour Advance ('Control' Group). DESIGN: Ten adult subjects were implanted with the DEE and fourteen with the Control. Electrode impedances were measured intra-operatively, one-week post-surgery, at initial activation (approximately two-weeks post-surgery), and at approximately one, three, six, 12 and 24 months post-activation. Two different impedance measurements were obtained: 1) in MP1+2 mode using Custom Sound programming software; and 2) 4-point impedance measures utilising BP+2 stimulation mode with recording on non-stimulating electrodes. Data were analysed with respect to both impedance averaged across all electrodes, and impedance for electrodes grouped into basal, middle and apical sections. RESULTS: Group mean MP1+2 impedance for the DEE was significantly lower than for the Control at all post-operative time points examined, and for each of the basal, middle and apical cochlear regions. Group mean 4-point impedance was significantly lower for the DEE than the Control in the basal region at six, 12 and 24 months post-activation and in the middle region at 12- and 24-months post-activation. The pattern of change in MP1+2 impedance differed significantly in the early post-operative period prior to device activation. A significant 4.8 kOhm reduction in impedance between surgery and one-week was observed for the DEE group but not for the Control. A 2.0 kOhm increase between the one and two week post-operative time points was observed for the Control but not for the DEE group. CONCLUSION: While rates of adoption of different surgical approaches differed between the groups and this may have had a confounding effect, the results suggest that passive elution of dexamethasone from the investigational device was associated with a change in the intracochlear environment following surgical implantation of the electrode array, as evidenced by the lower electrode impedance measures.

Cochlear Implant Outcomes in Patients With Severe Compared With Profound Hearing Loss.

OBJECTIVE: To compare the speech perception outcomes for patients with preoperative severe versus profound hearing loss with a cochlear implant (CI). STUDY DESIGN: Retrospective patient review. SETTING: Cochlear implant program. PATIENTS: Cochlear implant adult recipients (16 yr and above) having surgery between 2008 and 2015 with speech perception results and four frequency averaged severe (70-89 dBHL) or profound (90 dBHL and above) hearing loss. Prelingual deaf adults were included in the data. INTERVENTION: Cochlear implant. MAIN OUTCOME MEASURES: Speech perception scores with CUNY sentences and monosyllabic (CNC/CVC) word scores at preoperative and 3, 6, and 12 months postoperatively testing. Mann-Whitney U test was performed to compare outcomes of the two groups. Interquartile comparisons were also made. RESULTS: The severe group had significantly better speech perception than the profound hearing loss group for CUNY sentences and CNC/CVC word scores preoperatively (p < 0.001) (p < 0.001), at 6 months (p < 0.001) (p < 0.001), and at 12 months (p < 0.01) (p < 0.001), respectively. At 3 months there was no significant difference. The number of patients in each severe or profound group at the different time points ranged from 92 to 367 patients for CUNY sentences and from 52 to 216 patients for the word scores. The 12 months' lower quartile score for CUNY sentences for severe and profound groups was 83% and 75% respectively. The lower quartile score for words was 32% and 26% respectively. CONCLUSION: Adult CI recipients showed marked improvements in speech perception with a CI. Those with severe hearing loss have significantly better outcomes compared with profound hearing loss patients. These outcomes can inform CI candidacy evaluation criteria.

Neurotrophin gene augmentation by electrotransfer to improve cochlear implant hearing outcomes.

This Review outlines the development of DNA-based therapeutics for treatment of hearing loss, and in particular, considers the potential to utilize the properties of recombinant neurotrophins to improve cochlear auditory (spiral ganglion) neuron survival and repair. This potential to reduce spiral ganglion neuron death and indeed re-grow the auditory nerve fibres has been the subject of considerable pre-clinical evaluation over decades with the view of improving the neural interface with cochlear implants. This provides the context for discussion about the development of a novel means of using cochlear implant electrode arrays for gene electrotransfer. Mesenchymal cells which line the cochlear perilymphatic compartment can be selectively transfected with (naked) plasmid DNA using array - based gene electrotransfer, termed 'close-field electroporation'. This technology is able to drive expression of brain derived neurotrophic factor (BDNF) in the deafened guinea pig model, causing re-growth of the spiral ganglion peripheral neurites towards the mesenchymla cells, and hence into close proximity with cochlear implant electrodes within scala tympani. This was associated with functional enhancement of the cochlear implant neural interface (lower neural recruitment thresholds and expanded dynamic range, measured using electrically - evoked auditory brainstem responses). The basis for the efficiency of close-field electroporation arises from the compression of the electric field in proximity to the ganged cochlear implant electrodes. The regions close to the array with highest field strength corresponded closely to the distribution of bioreporter cells (adherent human embryonic kidney (HEK293)) expressing green fluorescent reporter protein (GFP) following gene electrotransfer. The optimization of the gene electrotransfer parameters using this cell-based model correlated closely with in vitro and in vivo cochlear gene delivery outcomes. The migration of the cochlear implant electrode array-based gene electrotransfer platform towards a clinical trial for neurotrophin-based enhancement of cochlear implants is supported by availability of a novel regulatory compliant mini-plasmid DNA backbone (pFAR4; plasmid Free of Antibiotic Resistance v.4) which could be used to package a 'humanized' neurotrophin expression cassette. A reporter cassette packaged into pFAR4 produced prominent GFP expression in the guinea pig basal turn perilymphatic scalae. More broadly, close-field gene electrotransfer may lend itself to a spectrum of potential DNA therapeutics applications benefitting from titratable, localised, delivery of naked DNA, for gene augmentation, targeted gene regulation, or gene substitution strategies.

Cochlear Implant Outcomes in Large Vestibular Aqueduct Syndrome-Should We Provide Cochlear Implants Earlier?

OBJECTIVE: Examine postoperative speech perception outcomes in a large vestibular aqueduct syndrome (LVAS) patients at a major cochlear implantation center. STUDY DESIGN: Retrospective analysis of the Sydney Cochlear Implant Centre (SCIC) database and medical records from January 1994 to December 2015 was performed. SETTING: Tertiary referral center. PATIENTS: Patients with a diagnosis of LVAS who received a cochlear implant (CI). Only those with speech perception outcomes recorded at least 12 months post implant were included in our analysis. INTERVENTION(S): Therapeutic. MAIN OUTCOME MEASURE(S): Postoperative speech perception scores. RESULTS: Between 1994 and 2015, 176 adult and pediatric patients with a diagnosis of LVAS underwent cochlear implantation at SCIC. Postoperative Bamford-Kowal Bench (BKB) sentence test scores were obtained for 97 patients. The postoperative median BKB score was 93% with a lower quartile score of 85% and an upper quartile score of 98%. Smaller numbers were available for post-CI City University of New York (CUNY) and Consonant-Nucleus-Consonant (CNC) word scores yet similar excellent results were seen. CONCLUSIONS: Our study results suggest the CI should be considered when BKB scores have dropped to 85%. We suggest that rather than LVAS cases representing a challenge to cochlear implantation, they are amongst the best candidates for surgery, and should receive a CI at an earlier stage in hearing loss, when they have better speech perception. This allows stable hearing to be established earlier along with excellent speech perception outcomes.

Bilateral duplication of the internal auditory canals and bilateral cochlear implant outcomes and review.

OBJECTIVES: Bilateral duplication of the internal auditory canal (IAC) is rare and is associated with profound sensorineural hearing loss. The present study aims to review our experience with bilateral cochlear implantation (CI) in children with a duplication of the IAC and to review the literature. METHODS: The Sydney Cochlear Implant Centre database was searched for children with duplication of the internal auditory canal. Data was collected regarding clinical history, MRI and CT findings, auditory brainstem responses (ABR), tympanometry and otoacoustic emissions (OAE), visually reinforced orientation audiometry, auditory brainstem response, electrocochleography (ECochG), transtympanic electrical auditory brainstem response (ABR), aided cortical evoked potentials (CAEP) and intraoperative neural response telemetry (NRT) and CI evoked electrical auditory brainstem testing. RESULTS: two children with bilateral duplication of the IAC were identified who successfully underwent bilateral cochlear implantation. Audiological development was monitored for 2 and 3 years respectively, both children could spontaneously verbalise and displayed Categories of Auditory Performance (CAP) score of 5 and 6 respectively. CONCLUSION: Children with duplication of the IAC, with accompanying cochlear nerve dysplasia (CND) can benefit from CI surgery, and verbal receptive and expressive language is possible.