Four-Point Impedance: A Potential Biomarker for Residual Hearing After Cochlear Implantation.

INTRODUCTION: Preservation of residual hearing after cochlear implantation allows for electroacoustic stimulation, which leads to better music appreciation, noise localization, and speech comprehension in noisy environments. Real-time intraoperative electrocochleography (rt-ECochG) monitoring has shown promise in improving residual hearing rates. Four-point impedance (4PI) is being explored as a potential biomarker in cochlear implantation that has been associated with fibrotic tissue response, hearing loss, and dizziness. In this study, we explore whether monitoring both rt-ECochG intraoperatively and postoperative 4PI improves predictions of the preservation of residual hearing. METHODS: This was a prospective cohort study. Adults with residual acoustic hearing underwent cochlear implantation with intraoperative intracochlear electrocochleography (ECochG) monitoring. The surgeon responded to a drop in ECochG signal amplitude of greater than 30% by a standardized manipulation of the electrode with the aim of restoring the ECochG. At the end of the procedure, the ECochG signal was categorized as being maintained or having dropped more than 30%. 4PI was measured on 1 day, 1 week, and 1 and 3 months after cochlear implantation. Residual hearing was measured by routine pure-tone audiogram at 3 months postoperatively. The ECochG category and 4PI impedance values were entered as factors in a multiple linear regression predicting the protection of residual hearing. RESULTS: Twenty-six patients were recruited. Rt-ECochG significantly predicted residual hearing at 3 months (t test; mean difference, 37.7%; p = 0.002). Inclusion of both 1-day or 3-month 4PI in a multiple linear regression with rt-ECochG markedly improved upon correlations with residual hearing compared with the rt-ECochG-only model (rt-ECochG and 1-d 4PI model, R2 = 0.67; rt-ECochG and 3-mo 4PI model, R2 = 0.72; rt-ECochG-only model, R2 = 0.33). CONCLUSIONS: Both rt-ECochG and 4PI predict preservation of residual hearing after cochlear implantation. These findings suggest that the biological response of the cochlea to implantation, as reflected in 4PI, is an important determinant of residual hearing, independent of the acute effects on hearing during implant surgery seen with rt-ECochG. We speculate that 4PI relates to inflammation 1 day after implantation and fibrosis at 3 months.

Four-Point Impedance and Utricular Dysfunction Is Associated with Postoperative Dizziness after Cochlear Implantation.

INTRODUCTION: Postimplantation dizziness is common, affecting approximately 50% of patients. Theories for dizziness include utricular inflammation, endolymphatic hydrops, and loss of perilymph. Four-point impedance (4PI) is a novel impedance measurement in cochlear implantation that shows potential to predict hearing loss, inflammation, and fibrotic tissue response. Here, we associate 4PI with dizziness after implantation and explore the link with utricular function. METHODS: Subjective visual vertical (SVV) as a measure of utricular function was recorded preoperatively as a baseline. 4PI was measured immediately postinsertion. Ongoing follow-up was performed at 1 day, 1 week, and 1 month, postoperatively. At each follow-up, 4PI, SVV, and the patients' subjective experience of dizziness were assessed. DISCUSSION: Thirty-eight adults were recruited. One-day 4PI was significantly higher in patients dizzy within the next week (254 Ω vs 171 Ω, p = 0.015). The optimum threshold on receiver operating characteristic curve was 190 Ω, above which patients had 10 times greater odds of developing dizziness (Fisher exact test, OR = 9.95, p = 0.0092). This suggests that 4PI varies with changes in the intracochlear environment resulting in dizziness, such as inflammation or hydrops. SVV significantly deviated away from the operated ear at 1 day (fixed effect estimate = 2.6°, p ≤ 0.0001) and 1 week (fixed effect estimate 2.7°, p ≤ 0.001). CONCLUSION: One-day 4PI is a potentially useful marker for detecting postoperative dizziness after cochlear implantation. Of the current theories for postoperative dizziness, inflammation might explain the findings seen here, as would changes in hydrostatic pressure. Future research should focus on detecting and exploring these labyrinthine changes in further detail.

Four-Point Impedance Changes After Cochlear Implantation for Lateral Wall and Perimodiolar Implants.

OBJECTIVE: Monitor four-point impedance in cochlear implant recipients over time and determine if implant type, surgical approach, and electrode positioning affected impedance measurements. STUDY DESIGN: Prospective observational. SETTING: Hospital. PATIENTS: Adult cochlear implant recipients implanted with a perimodiolar or lateral wall cochlear implant. MAIN OUTCOME MEASURES: Mean values for four-point impedances were calculated for all electrode contacts at perioperative and 3 months after surgery. Linear mixed models were applied to the impedance data to compare between implant types and time points. The angular insertion depth and electrode position relative to the medial and lateral wall, commonly termed the Intracochlear Position Index (ICPI), were collected and compared with impedance measurements. RESULTS: Perioperatively, the four-point impedance was similar between implant types, with perimodiolar implants having marginally higher impedance values in the basal region. At 3 months after surgery, impedances significantly increased in the basal half of the electrode array for both implants, with higher impedance values for CI532 implants. There were no significant differences in insertion angle depth between implant types. The ICPI values for the seven most basal electrodes were similar for both implants; however, CI532 arrays were significantly more medially placed along the remaining apical portion of the array, which is expected. ICPI values did not correlate with impedance measurements for either implant. CONCLUSIONS: Four-point impedance increases at 3 months after surgery may reflect fibrous tissue formation after cochlear implantation. The higher impedance values in perimodiolar implants may reflect a more extensive fibrosis formation as a result of surgical approaches used, requiring drilling of the cochlea bone.

Homograft Versus Valves and Valved Conduits for Extensive Aortic Valve Endocarditis with Aortic Root Involvement/Destruction: A Systematic Review and Meta-Analysis.

Aortic valve infective endocarditis is a life-threatening condition. Patients frequently present profoundly unwell and extensive surgery may be required to correct the underlying anatomical deficits and control sepsis. Periannular involvement occurs in more than 10% of patients with aortic valve endocarditis. Complex aortic valve endocarditis has a mortality rate of 10 to 40%. Longstanding surgical dogma suggests homografts represent the optimal replacement option in complex aortic valve endocarditis; however, there is a paucity of evidence and lack of consensus on the optimal replacement choice. A systematic review and meta-analysis was performed utilizing EMBASE, PubMed, and the Cochrane databases to review articles describing homografts versus aortic valve replacement and/or valved conduit graft implantation for complex aortic valve endocarditis. The outcomes of interest were mortality, reinfection, and reoperation. Eleven studies were included in this meta-analysis, contributing 810 episodes of complex aortic valve endocarditis. All included reports were cohort studies. There was no statistically significant difference in overall mortality (risk ratio [RR] 0.99; 95% confidence interval [CI], 0.61-1.59; p = 0.95), reinfection (RR 0.89; 95% CI, 0.45-1.78; p = 0.74), or reoperation (RR 0.91; 95% CI, 0.38-2.14; p = 0.87) between the homograft and valve replacement/valved conduit graft groups. Overall, there was no difference in mortality, reinfection, or reoperation rates between homografts and other valve or valved conduits in management of complex aortic endocarditis. However, there is a paucity of high-quality evidence in the area, and comparison of valve types warrants further investigation.

Metal stents are safe and cost-effective for preoperative biliary drainage in resectable pancreaticobiliary tumours.

BACKGROUNDS: To compare the complication rates and overall costs of self-expandable metal stents (SEMS) and plastic stents (PS) in clinically indicated preoperative biliary drainage (PBD) prior to a pancreatoduodenectomy (PD). METHODS: We conducted an Australian multicentre retrospective cohort study using the databases of four tertiary hospitals. Adult patients who underwent clinically indicated endoscopic PBD prior to PD from 2010 to 2019 were included. Rates of complications attributable to PBD, surgical complications and pre-operative endoscopic re-intervention were calculated. Costing data were retrieved from our Financial department. RESULTS: Among the 157 included patients (mean age 66.6 ± 9.8 years, 45.2% male), 49 (31.2%) received SEMS and 108 received PS (68.8%). Baseline bilirubin was 187.5 ± 122.6 µmol/L. Resection histopathology showed mainly adenocarcinoma (93.0%). Overall SEMS was associated less complications (12.2% vs. 28.7%, p = 0.02) and a lower pre-operative endoscopic re-intervention rate (4.3 vs. 20.8%, p = 0.03) compared with PS. There was no difference in post-PD complication rates. On multivariate logistic regression analysis, stent type was an independent risk factor of PBD complication (OR of SEMS compared to PS 0.24, 95% CI 0.07-0.79, p = 0.02) but not for any secondary outcome measures. Upfront material costs were $56USD for PS and $1991USD for SEMS. Accounting for rates of complications, average costs were similar ($3110USD for PS and $3026USD for SEMS). CONCLUSION: In resectable pancreaticobiliary tumours, SEMS for PBD was associated with reduced risk of overall PBD-related complications and pre-surgical endoscopic reintervention rates and was comparable to PS in terms of overall cost.

An approach to neck masses in adults.

BACKGROUND: Neck masses in adults are a common presentation for head and neck cancer. Head and neck cancer accounts for 3.4% of all malignancies in Australia, and the incidence of oropharyngeal squamous cell carcinoma is rising. Early diagnosis is essential to prevent worsening prognosis. OBJECTIVE: This article provides a brief overview of neck masses in adults, with a guideline to work-up and management in a primary care setting. DISCUSSION: All neck masses should be considered malignant until proven otherwise. Detailed history and examination is crucial in the initial work-up. Fine-needle aspiration and computed tomography of the neck with contrast make up the mainstay of first-line investigation.

A coenzima Q10 produz efeito sobre a prevenção da miringoesclerose?: Estudo experimental com ratos / Is there any effect of coenzyme Q10 on prevention of myringosclerosis?: Experimental study with rats

Estudos recentes demonstram que a formação de miringoesclerose pode ser reduzida pela aplicação de enzimas e elementos antioxidantes. OBJETIVO: Investigar a eficácia da coenzima Q10 na prevenção de miringoesclerose experimentalmente induzida. MÉTODO: Quarenta e oito ratas Wistar albinas saudáveis sofreram miringotomia e foram divididas aleatoriamente em quatro grupos. O Grupo A não recebeu tratamento algum; o Grupo B recebeu coenzima Q10 por via oral; o Grupo C foi tratado com soro fisiológico tópico; e o Grupo D recebeu coenzima Q10 tópica. No 15º dia de tratamento, as membranas timpânicas foram examinadas por otomicroscopia. As lesões miringoescleróticas foram documentadas de forma semiquantitativa por meio de uma escala de quatro pontos. Após a coleta, as membranas timpânicas foram avaliadas por histopatologia. RESULTADOS: No grupo D (coenzima Q10 tópica) foi observada a ocorrência de otite nos primeiros quatro dias do estudo, o que levou à sua exclusão do estudo. O exame de otomicroscopia não revelou diferenças significativas entre grupos em termos de formação de miringoesclerose (p = 0,241). Diferenças estatisticamente significativas foram observada quando os exames histopatológicos do grupo A foram comparados aos dos grupos B e C (p = 0,004; p < 0,001, respectivamente). Não houve diferença significativa entre os grupos B e C (p = 0,160). CONCLUSÃO: A administração oral de coenzima Q10 não reduziu a formação de miringoesclerose nos ratos submetidos à miringotomia.

Recent studies have shown that the formation of myringosclerosis could be reduced by the application of antioxidant enzymes and elements. OBJECTIVE: The aim of this study was to investigate the effectiveness of coenzyme Q10 on the prevention of experimentally induced myringosclerosis. METHOD: Forty-eight healthy female wistar albino rats were bilaterally myringotomized and divided into four groups randomly. Group A received no treatment, group B was administered oral coenzyme Q10. Group C was treated with topical saline solution, group D received topically coenzyme Q10. On the 15th day of treatment, tympanic membranes were examined by otomicroscopy. Myringosclerotic lesions were documented semiquantitatively by using 4-point scale. After harvesting tympanic membranes were evaluated histopathologically. RESULTS: In group D (topical coenzyme Q10), we observed otitis within the first four days of the study and this group was excluded from the study. Regarding otomicroscopic examinations, there were no significant differences among groups in myringosclerosis formation (p = 0.241). When group A (non treatment) compared to groups B and C regarding histopathologic examination, the results demonstrated statistical significant differences (p = 0.004; p < 0.001), respectively. There was no statisticaly significant difference between groups B and C (p = 0.160). CONCLUSION: Oral administration of coenzyme Q10 did not reduce myringosclerosis formation in myringotomized rats.