How differ eCAP types in cochlear implants users with and without inner ear malformations: amplitude growth function, spread of excitation, refractory recovery function.

OBJECTIVES: Inner ear malformations (IEMs) may result in differences in outcomes of cochlear implant user. These differences could be observed in both behavioral and objective tests. eCAP is the most common used objective test in cochlear implants and have different presence rate in cochlear implant users with and without IEMs. This study aims to evaluate eCAP results from CI user with and without IEMs through different recoding methods; amplitude growth function, spreads of excitation and refractory recovery. METHODS: There were 42 CI users (20 IEM&22 normal) above five-years old and with at least one year experience. Three different eCAP measurement was conducted at several intracochlear electrodes. Presence rate, threshold levels and amplitude were compared between groups. RESULTS: For Amplitude growth function measurement, when the percentage of detected eCAP thresholds was analyzed between groups, there was a significant difference only for basal electrode and no significant difference for apical and middle electrodes. Similarly, the presence rate of RecF-eCAP for both groups were in a downward trend from apical to basal. However, there was no significant difference in AGF-eCAP and RecF-eCAP amplitudes between groups for the cochlea's apical, middle and basal region. Although the presence rate of SOE-eCAP was lower for IEM group, there was no significant difference in ECAP amplitudes for all maskers. CONCLUSIONS: It could be inferred that even though the observable eCAP rate differed between these two groups when the observable eCAP was recorded, the IEM group produced eCAP with similar amplitudes to normal cochlea group.

Exploring the microbial landscape: uncovering the pathogens associated with community-acquired pneumonia in hospitalized patients.

Objectives: This study aimed to investigate the etiology, clinical features, and outcomes of community-acquired pneumonia (CAP) in adults. Understanding the causative pathogens is essential for effective treatment and prevention. Design: Between 2016-2018, 518 hospitalized adults with CAP and 241 controls without symptoms were prospectively enrolled. Urine samples were collected for pneumococcal urinary antigen tests and nasopharyngeal swabs for viral and bacterial analysis, combined with routine diagnostic care. Results: Among the included CAP patients, Streptococcus pneumoniae was the most common pathogen, detected in 28% of patients, followed by Haemophilus influenzae in 16%. Viruses were identified in 28%, and concurrent viruses and bacteria were detected in 15%. There was no difference in mortality, length of stay, or symptoms at hospitalization when comparing patients with bacterial, viral, or mixed etiologies. Among the control subjects without respiratory symptoms, S. pneumoniae, H. influenzae, or Moraxella catarrhalis were detected in 5-7%, and viruses in 7%. Conclusion: Streptococcus pneumoniae emerged as the predominant cause of CAP, followed closely by viruses and H. influenzae. Intriguingly, symptoms and outcome were similar regardless of etiology. These findings highlight the complexity of this respiratory infection and emphasize the importance of comprehensive diagnostic and treatment strategies.Clinical Trial Registration: ClinicalTrials.gov, identifier [NCT03606135].

A Prospective Multicenter Case Series Utilizing Intraoperative Neuromonitoring With Evoked Compound Action Potentials to Confirm Spinal Cord Stimulation Lead Placement.

OBJECTIVES: The use of intraoperative neuromonitoring (IONM) has been adapted to address issues of safety and proper lead positioning in spinal cord stimulation. This multicenter case series seeks to incorporate the use of evoked compound action potential (ECAP) and late response (LR) recording and compare it with the results obtained with IONM, specifically electromyography (EMG), for the confirmation of lead placement. This study aimed to establish a correlation between ECAPs, LR, and EMG and publish human recordings of ECAPs and LR during their use with IONM. MATERIALS AND METHODS: Standard neuromonitoring protocols were followed at two institutions, with two separate physicians and with seven patients, as part of a larger ongoing study registered with ClinicalTrials.gov (NCT02924129). Stimulation and recording were performed, top and bottom, on each percutaneous lead. Stimulation amplitude was increased considering ECAP, LR, and EMG thresholds. RESULTS: ECAPs, LRs, and EMG signals were observed in all patients. The onset of LR signals on implanted electrodes and EMG signal on subdermal electrodes was well correlated (rs = 0.94, p < 0.001), with a median LR:EMG value of 1.06 (N = 21). LR:EMG for the top (mean = 0.97, N = 8) vs bottom (mean = 1.15, N = 13) of the lead was compared using a paired Wilcoxon signed rank test and an independent samples Mann-Whitney test, revealing a marginally significant and a statistically significant difference (p = 0.078 and p = 0.015, respectively). Mean LR:ECAP was >2 in all locations and approximately 3.5 overall. LR:ECAP between the top and bottom of the lead was significantly different (Wilcoxon test, p < 0.01, N = 12). CONCLUSIONS: LR correlated with EMG; leads with bilateral (not necessarily symmetric) EMG activity showed LR:ECAP > 1.5. An LR:ECAP of <1, with LR/EMG generated before the ECAP, indicated that the lead is too lateral. The use of ECAP and LR has the potential of maintaining objective lead placement, without the need for needle placement with IONM.

Using the electrically-evoked compound action potential (ECAP) interphase gap effect to select electrode stimulation sites in cochlear implant users.

Studies in cochlear implanted animals show that the IPG Effect for ECAP growth functions (i.e., the magnitude of the change in ECAP amplitude growth function (AGF) slope or peak amplitude when the interphase gap (IPG) is increased) can be used to estimate the densities of spiral ganglion neurons (SGNs) near the electrode stimulation and recording sites. In humans, the same ECAP IPG Effect measures correlate with speech recognition performance. The present study examined the efficacy of selecting electrode sites for stimulation based on the IPG Effect, in order to improve performance of CI users on speech recognition tasks. We measured the ECAP IPG Effect for peak amplitude in adult (>18 years old) CI users (N= 18 ears), and created experimental programs to stimulate electrodes with either the highest or lowest ECAP IPG Effect for peak amplitude. Subjects also listened to a program without any electrodes deactivated. In a subset of subject ears (11/18), we compared performance differences between the experimental programs to post-operative computerized tomography (CT) scans to examine underlying factors that might contribute to the efficacy of an electrode site-selection approach. For sentences-in-noise, average performance was better when subjects listened to the experimental program that stimulated electrodes with the highest rather than the lowest IPG Effect for ECAP peak amplitude. A similar pattern was noted for transmission and perception of consonant place cues in a consonant recognition task. However, on average, performance when listening to a program with higher IPG Effect values was equal to that when listening with all electrodes activated. Results also suggest that scalar location (scala tympani or vestibuli) should be considered when using an ECAP-based electrode site-selection procedure to optimize CI performance.

Unravelling the temporal properties of human eCAPs through an iterative deconvolution model.

OBJECTIVE: The electrically evoked compound action potential (eCAP) has been widely studied for its clinical value in evaluating cochlear implants (CIs). However, to date, single-fiber recordings have not been recorded from the human auditory nerve, and many unknowns remain about the firing properties that underlie the eCAP in patients with CIs. In particular, the temporal properties of auditory nerve fiber firing might contain valuable information that may be used to estimate the condition of the surviving auditory nerve fibers. This study aimed to evaluate the temporal properties of neural firing underlying human eCAPs with a new deconvolution model. DESIGN: Assuming that each auditory nerve fiber produces the same unitary response (UR), the eCAP can be seen as a convolution of a UR with a compound discharge latency distribution (CDLD). We developed an iterative deconvolution model that derived a two-component Gaussian CDLD and a UR from recorded eCAPs. The choices were based on a deconvolution fitting error minimization routine (DMR). The DMR iteratively minimized the error between the recorded human eCAPs and the eCAPs simulated by the convolution of a parameterised UR and CDLD model (instead of directly deconvolving recorded eCAPs). Our new deconvolution model included two separate steps. In step one, the underlying URs of all eCAPs were derived, and the average of these URs was called the human UR. In step two, the CDLD was obtained by using the DMR in combination with the estimated human UR. With this model, we investigated the temporal firing properties of eCAPs by analysing the CDLDs, including the amplitudes, widths, peak latencies, and areas of CDLDs. The differences of the temporal properties in eCAPs between children and adults were explored. Finally, we validated the two-Gaussian component CDLD model with a multiple-Gaussian component CDLD model. RESULTS: The estimated human UR contained a sharper, narrower negative component and a wider positive phase, compared to the previously described guinea pig UR. Furthermore, the eCAPs from humans could be predicted by the convolution of the human UR with a two-Gaussian component CDLD. The areas under CDLD (AUCD) reflected the number of excited nerve fibers over time. Both the CDLD magnitudes and AUCDs were significantly correlated with the eCAP amplitudes. Furthermore, different eCAPs with the same amplitude could lead to greatly different AUCDs. Significant differences of the temporal properties of eCAPs between children and adults were found. At last, the two-Gaussian component CDLD model was validated as the most optimal CDLD model. CONCLUSION: This study described an iterative method that deconvolved human eCAPs into CDLDs, under the assumption that auditory nerve fibers had the same electrically evoked UR. Based on human eCAPs, we found a human UR that was different from the guinea pig UR. Furthermore, we found that CDLD characteristics revealed age-related temporal differences between human eCAPs. This temporal information may contain valuable clinical information on the survival and function of auditory nerve fibers. In turn, the surviving nerve condition might have prognostic value for speech outcomes in patients with CIs.