Detection of Extracochlear Electrodes in Cochlear Implants with Electric Field Imaging/Transimpedance Measurements: A Human Cadaver Study.

OBJECTIVES: Extracochlear electrodes in cochlear implants (CI), defined as individual electrodes on the electrode array located outside of the cochlea, are not a rare phenomenon. The presence of extracochlear electrodes frequently goes unnoticed and could result in them being assigned stimulation frequencies that are either not delivered to, or stimulating neurons that overlap with intracochlear electrodes, potentially reducing performance. The current gold-standard for detection of extracochlear electrodes is computed tomography (CT), which is time-intensive, costly and involves radiation. It is hypothesized that a collection of Stimulation-Current-Induced Non-Stimulating Electrode Voltage recordings (SCINSEVs), commonly referred to as "transimpedance measurements (TIMs)" or electric field imaging (EFI), could be utilized to detect extracochlear electrodes even when contact impedances are low. An automated analysis tool is introduced for detection and quantification of extracochlear electrodes. DESIGN: Eight fresh-frozen human cadaveric heads were implanted with the Advanced Bionics HiRes90K with a HiFocus 1J lateral-wall electrode. The cochlea was flushed with 1.0% saline through the lateral semicircular canal. Contact impedances and SCINSEVs were recorded for complete insertion and for 1 to 5 extracochlear electrodes. Measured conditions included: air in the middle ear (to simulate electrodes situated in the middle ear), 1.0% saline in the middle ear (to simulate intraoperative conditions with saline or blood in the middle ear), and soft tissue (temporal muscle) wrapped around the extracochlear electrodes (to simulate postoperative soft-tissue encapsulation of the electrodes). Intraoperative SCINSEVs from patients were collected, for clinical purposes during slow insertion of the electrode array, as well as from a patient postoperatively with known extracochlear electrodes. RESULTS: Full insertion of the cochlear implant in the fresh-frozen human cadaveric heads with a flushed cochlea resulted in contact impedances in the range of 6.06 ± 2.99 kΩ (mean ± 2SD). Contact impedances were high when the extracochlear electrodes were located in air, but remained similar to intracochlear contact impedances when in saline or soft tissue. SCINSEVs showed a change in shape for the extracochlear electrodes in air, saline, and soft tissue. The automated analysis tool showed a specificity and sensitivity of 100% for detection of two or more extracochlear electrodes in saline and soft tissue. The quantification of two or more extracochlear electrodes was correct for 84% and 81% of the saline and soft tissue measurements, respectively. CONCLUSIONS: Our analysis of SCINSEVs (specifically the EFIs from this manufacturer) shows good potential as a detection tool for extracochlear electrodes, even when contact impedances remain similar to intracochlear values. SCINSEVs could potentially replace CT in the initial screening for extracochlear electrodes. Detecting migration of the electrode array during the final stages of surgery could potentially prevent re-insertion surgery for some CI users. The automated detection tool could assist in detection and quantification of two or more extracochlear electrodes

Practicable assessment of cochlear size and shape from clinical CT images

Abstract: There is considerable interpersonal variation in the size and shape of the human cochlea, with evident consequences for cochlear implantation. The ability to characterize a specific cochlea, from preoperative computed tomography (CT) images, would allow the clinician to personalize the choice of electrode, surgical approach and postoperative programming. In this study, we present a fast, practicable and freely available method for estimating cochlear size and shape from clinical CT. The approach taken is to fit a template surface to the CT data, using either a statistical shape model or a locally affine deformation (LAD). After fitting, we measure cochlear size, duct length and a novel measure of basal turn non-planarity, which we suggest might correlate with the risk of insertion trauma. Gold-standard measurements from a convenience sample of 18 micro-CT scans are compared with the same quantities estimated from low-resolution, noisy, pseudo-clinical data synthesized from the same micro-CT scans. The best results were obtained using the LAD method, with an expected error of 8–17% of the gold-standard sample range for non-planarity, cochlear size and duct length

A systematic review on prevention and management of wound infections from cochlear implantation.

OBJECTIVE OF REVIEW: Surgical site infections are a recognised complication of cochlear implant (CI) surgery with significant morbidity. Our aim was to search for the optimum prevention and management strategy to deal with this issue. TYPE OF REVIEW: Systematic review. SEARCH STRATEGY: A systematic literature search was undertaken from the databases of Embase, CINAHL, MEDLINE® , Web of Science, Scopus and Cochrane Library according to the predefined inclusion and exclusion criteria. EVALUATION METHOD: All relevant titles, abstracts and full-text articles were reviewed by two authors who resolved any differences by discussion and consultation with senior authors. RESULTS: Fourteen articles were included in our review. The overall quality of evidence was low with the vast majority of the studies being retrospective case series and expert opinions. No randomised controlled trials were noted. We found consistent reports that intraoperative prophylactic antibiotics should be given to all patients undergoing CI and that the vast majority of CI wound infections had grown Staphylococcal spp. or Pseudomonas spp. CONCLUSION: Our review has not identified any reliable or reproducible strategies to prevent and deal with wound infections after CI. We strongly encourage further research within this field and would suggest that a consensus of opinions from a multidisciplinary panel of experts may be a pragmatic way forward as an effective guide

Eustachian tube dysfunction: A diagnostic accuracy study and proposed diagnostic pathway.

BACKGROUND AND AIMS: Eustachian tube dysfunction (ETD) is a commonly diagnosed disorder of Eustachian tube opening and closure, which may be associated with severe symptoms and middle ear disease. Currently the diagnosis of obstructive and patulous forms of ETD is primarily based on non-specific symptoms or examination findings, rather than measurement of the underlying function of the Eustachian tube. This has proved problematic when selecting patients for treatment, and when designing trial inclusion criteria and outcomes. This study aims to determine the correlation and diagnostic value of various tests of ET opening and patient reported outcome measures (PROMs), in order to generate a recommended diagnostic pathway for ETD. METHODS: Index tests included two PROMs and 14 tests of ET opening (nine for obstructive, five for patulous ETD). In the absence of an accepted reference standard two methods were adopted to establish index test accuracy: expert panel diagnosis and latent class analysis. Index test results were assessed with Pearson correlation and principle component analysis, and test accuracy was determined. Logistic regression models assessed the predictive value of grouped test results. RESULTS: The expert panel diagnosis and PROMs results correlated with each other, but not with ET function measured by tests of ET opening. All index tests were found to be feasible in clinic, and acceptable to patients. PROMs had very poor specificity, and no diagnostic value. Combining the results of tests of ET function appeared beneficial. The latent class model suggested tympanometry, sonotubometry and tubomanometry have the best diagnostic performance for obstructive ETD, and these are included in a proposed diagnostic pathway. CONCLUSIONS: ETD should be diagnosed on the basis of clinical assessment and tests of ET opening, as PROMs have no diagnostic value. Currently diagnostic uncertainty exists for some patients who appear to have intermittent ETD clinically, but have negative index test results.M.S. received funding from the Cambridge Hearing Trus

Eustachian tube dysfunction: A diagnostic accuracy study and proposed diagnostic pathway

<div><p>Background and aims</p><p>Eustachian tube dysfunction (ETD) is a commonly diagnosed disorder of Eustachian tube opening and closure, which may be associated with severe symptoms and middle ear disease. Currently the diagnosis of obstructive and patulous forms of ETD is primarily based on non-specific symptoms or examination findings, rather than measurement of the underlying function of the Eustachian tube. This has proved problematic when selecting patients for treatment, and when designing trial inclusion criteria and outcomes. This study aims to determine the correlation and diagnostic value of various tests of ET opening and patient reported outcome measures (PROMs), in order to generate a recommended diagnostic pathway for ETD.</p><p>Methods</p><p>Index tests included two PROMs and 14 tests of ET opening (nine for obstructive, five for patulous ETD). In the absence of an accepted reference standard two methods were adopted to establish index test accuracy: expert panel diagnosis and latent class analysis. Index test results were assessed with Pearson correlation and principle component analysis, and test accuracy was determined. Logistic regression models assessed the predictive value of grouped test results.</p><p>Results</p><p>The expert panel diagnosis and PROMs results correlated with each other, but not with ET function measured by tests of ET opening. All index tests were found to be feasible in clinic, and acceptable to patients. PROMs had very poor specificity, and no diagnostic value. Combining the results of tests of ET function appeared beneficial. The latent class model suggested tympanometry, sonotubometry and tubomanometry have the best diagnostic performance for obstructive ETD, and these are included in a proposed diagnostic pathway.</p><p>Conclusions</p><p>ETD should be diagnosed on the basis of clinical assessment and tests of ET opening, as PROMs have no diagnostic value. Currently diagnostic uncertainty exists for some patients who appear to have intermittent ETD clinically, but have negative index test results.</p></div

Protocol for a multicentre randomised controlled trial of STeroid Administration Routes For Idiopathic Sudden sensorineural Hearing loss:The STARFISH trial

Idiopathic sudden sensorineural hearing loss (ISSNHL) is the rapid onset of reduced hearing due to loss of function of the inner ear or hearing nerve of unknown aetiology. Evidence supports improved hearing recovery with early steroid treatment, via oral, intravenous, intratympanic or a combination of routes. The STARFISH trial aims to identify the most clinically and cost-effective route of administration of steroids as first-line treatment for ISSNHL. STARFISH is a pragmatic, multicentre, assessor-blinded, three-arm intervention, superiority randomised controlled trial (1:1:1) with an internal pilot (ISRCTN10535105, IRAS 1004878). 525 participants with ISSNHL will be recruited from approximately 75 UK Ear, Nose and Throat units. STARFISH will recruit adults with sensorineural hearing loss averaging 30dBHL or greater across three contiguous frequencies (confirmed via pure tone audiogram), with onset over a ≤3-day period, within four weeks of randomisation. Participants will be randomised to 1) oral prednisolone 1mg/Kg/day up to 60mg/day for 7 days; 2) intratympanic dexamethasone: three intratympanic injections 3.3mg/ml or 3.8mg/ml spaced 7±2 days apart; or 3) combined oral and intratympanic steroids. The primary outcome will be absolute improvement in pure tone audiogram average at 12-weeks following randomisation (0.5, 1.0, 2.0 and 4.0kHz). Secondary outcomes at 6 and 12 weeks will include: Speech, Spatial and Qualities of hearing scale, high frequency pure tone average thresholds (4.0, 6.0 and 8.0kHz), Arthur Boothroyd speech test, Vestibular Rehabilitation Benefit Questionnaire, Tinnitus Functional Index, adverse events and optional weekly online speech and pure tone hearing tests. A health economic assessment will be performed, and presented in terms of incremental cost effectiveness ratios, and cost per quality-adjusted life-year. Primary analyses will be by intention-to-treat. Oral prednisolone will be the reference. For the primary outcome, the difference between group means and 97.5% confidence intervals at each time-point will be estimated via a repeated measures mixed-effects linear regression model

Wideband acoustic immittance measurements in assessing crimping status following stapedotomy : A temporal bone study

Objective: To ascertain if wideband acoustic immitance (WAI) measurements are useful in assessing crimping status following stapedotomy. Design: WAI measurements were obtained using the Mimosa Acoustics HearID system. Wideband chirp sound stimuli and a set of tone stimuli for nine frequencies between 0.2 and 6 kHz were used at 60 dB SPL. Five sets of measurements were performed on each temporal bone: mobile stapes, stapes fixation and stapedotomy followed by insertion of a tightly crimped, a loosely crimped and an uncrimped prosthesis. Study sample: Eight fresh-frozen temporal bones were harvested from human cadaveric donors. Results: At lower frequencies, up to 1 kHz, stapes fixation decreased absorbance. Compared to the baseline absorbance, absorbance with stapes fixation dropped by 6 to 17% in absolute terms from the baseline value (p = 0.027). Absorbance was not affected in higher frequencies (p = 0.725). Stapedotomy changed the absorbance curve significantly compared to the normal condition with an increase of absolute absorbance values by 6 to 36% around 0.25–1 kHz (p-valu

Wideband acoustic immittance measurements in assessing crimping status following stapedotomy : A temporal bone study

Objective: To ascertain if wideband acoustic immitance (WAI) measurements are useful in assessing crimping status following stapedotomy. Design: WAI measurements were obtained using the Mimosa Acoustics HearID system. Wideband chirp sound stimuli and a set of tone stimuli for nine frequencies between 0.2 and 6 kHz were used at 60 dB SPL. Five sets of measurements were performed on each temporal bone: mobile stapes, stapes fixation and stapedotomy followed by insertion of a tightly crimped, a loosely crimped and an uncrimped prosthesis. Study sample: Eight fresh-frozen temporal bones were harvested from human cadaveric donors. Results: At lower frequencies, up to 1 kHz, stapes fixation decreased absorbance. Compared to the baseline absorbance, absorbance with stapes fixation dropped by 6 to 17% in absolute terms from the baseline value (p = 0.027). Absorbance was not affected in higher frequencies (p = 0.725). Stapedotomy changed the absorbance curve significantly compared to the normal condition with an increase of absolute absorbance values by 6 to 36% around 0.25–1 kHz (p-valu

A systematic review of the effect of different crimping techniques in stapes surgery for otosclerosis.

OBJECTIVES/HYPOTHESIS To evaluate the effect of crimping techniques in stapes surgery for otosclerosis patients measured by hearing outcomes on pure-tone audiometry. DATA SOURCES PubMed, EMBASE, and the Cochrane Library. METHODS A systematic search was conducted. Studies comparing the effect of different crimping methods on pure-tone audiometric results in patients undergoing stapes surgery for otosclerosis were included. Relevance and risk of bias were assessed. Absolute risks and risk differences, means and mean differences, and 95% confidence intervals were extracted or calculated for the primary and secondary outcomes, which were air-bone gap closure to 10 dB or less, mean postoperative air-bone gap, and postoperative sensorineural hearing loss. RESULTS Twenty-two studies with moderate or high risk of bias were included for data extraction. Air-bone gap closure to 10 dB or less was assessed in 17 studies and mean postoperative air-bone gap in 20 studies. The hearing outcomes did not consistently favor one crimping method. However, the differences that were statistically significant were consistently in favor of heat crimping over manual and no crimping (difference in air-bone gap closure to 10 dB or less ranged between 22% and 42% in these studies and difference in mean postoperative air-bone gap between 2.8 dB and 7.4 dB) and in favor of manual crimping over no crimping (30% difference in air-bone gap closure to 10 dB or less and difference in mean postoperative air-bone gap between 2.6 dB and 6.0 dB). CONCLUSION Moderate to high risk of bias and inconsistent results characterize the current evidence

A systematic review of the effect of different crimping techniques in stapes surgery for otosclerosis.

OBJECTIVES/HYPOTHESIS To evaluate the effect of crimping techniques in stapes surgery for otosclerosis patients measured by hearing outcomes on pure-tone audiometry. DATA SOURCES PubMed, EMBASE, and the Cochrane Library. METHODS A systematic search was conducted. Studies comparing the effect of different crimping methods on pure-tone audiometric results in patients undergoing stapes surgery for otosclerosis were included. Relevance and risk of bias were assessed. Absolute risks and risk differences, means and mean differences, and 95% confidence intervals were extracted or calculated for the primary and secondary outcomes, which were air-bone gap closure to 10 dB or less, mean postoperative air-bone gap, and postoperative sensorineural hearing loss. RESULTS Twenty-two studies with moderate or high risk of bias were included for data extraction. Air-bone gap closure to 10 dB or less was assessed in 17 studies and mean postoperative air-bone gap in 20 studies. The hearing outcomes did not consistently favor one crimping method. However, the differences that were statistically significant were consistently in favor of heat crimping over manual and no crimping (difference in air-bone gap closure to 10 dB or less ranged between 22% and 42% in these studies and difference in mean postoperative air-bone gap between 2.8 dB and 7.4 dB) and in favor of manual crimping over no crimping (30% difference in air-bone gap closure to 10 dB or less and difference in mean postoperative air-bone gap between 2.6 dB and 6.0 dB). CONCLUSION Moderate to high risk of bias and inconsistent results characterize the current evidence