The Effects of Substance Misuse on Auditory and Vestibular Function: A Systematic Review

BACKGROUND

Chronic substance misuse is an ongoing and significant public health concern. Among a myriad of health complications that can occur, substance misuse potentially causes ototoxic effects. Case reports, retrospective chart data, and a few cohort studies suggest that certain prescription opioids and illicit drugs can have either temporary or permanent effects on auditory and/or vestibular function. Given the steady rise of people with a substance-use disorder (SUD), it is of growing importance that audiologists and otolaryngologists have an insight into the potential ototoxic effects of substance misuse.

OBJECTIVES

A systematic review was conducted to (1) synthesize the literature on the illicit drugs, prescription opioids, and alcohol misuse on the auditory and vestibular systems, (2) highlight common hearing and vestibular impairments for each substance class, and (3) discuss the limitations of the literature, the potential mechanisms, and clinical implications for clinicians who may encounter patients with hearing or vestibular loss related to substance misuse, and describe opportunities for further study.

DESIGN

Systematic searches were performed via PubMed, Scopus, and Google Scholar, and the final updated search was conducted through March 30, 2022. Inclusion criteria included peer-reviewed articles, regardless of study design, from inception until the present that included adults with chronic substance misuse and hearing and/or vestibular complaints. Articles that focused on the acute effects of substances in healthy people, ototoxicity from already known ototoxic medications, the relationship between hearing loss and development of a SUD, articles not available in English, animal work, and duplicates were excluded. Information on the population (adults), outcomes (hearing and/or vestibular data results), and study design (e.g., case report, cohort) were extracted. A meta-analysis could not be performed because more than 60% of the studies were single-case reports or small cohort.

RESULTS

The full text of 67 studies that met the eligibility criteria were selected for the review. Overall, 21 studies reported associations between HL/VL related to illicit drug misuse, 28 studies reported HL/VL from prescription opioids, and 20 studies reported HL/VL related to chronic alcohol misuse (2 studies spanned more than one category). Synthesis of the findings suggested that the misuse and/or overdose of amphetamines and cocaine was associated with sudden, bilateral, and temporary HL, whereas HL from the combination of a stimulant and an opioid often presented with greater HL in the mid-frequency range. Reports of temporary vertigo or imbalance were mainly associated with illicit drugs. HL associated with misuse of prescription opioids was typically sudden or rapidly progressive, bilateral, moderately severe to profound, and in almost all cases permanent. The misuse of prescription opioids occasionally resulted in peripheral VL, especially when the opioid misuse was long term. Chronic alcohol misuse tended to associate with high-frequency sudden or progressive sensorineural hearing loss, or retrocochlear dysfunction, and a high occurrence of central vestibular dysfunction and imbalance.

CONCLUSIONS

Overall, chronic substance misuse associates with potential ototoxic effects, resulting in temporary or permanent hearing and/or vestibular dysfunction. However, there are notable limitations to the evidence from the extant literature including a lack of objective test measures used to describe hearing or vestibular effects associated with substance misuse, small study sample sizes, reliance on case studies, lack of controlling for confounders related to health, age, sex, and other substance-use factors. Future large-scale studies with prospective study designs are needed to further ascertain the role and risk factors of substance misuse on auditory and vestibular function and to further clinical management practices.

A Comparison of Montreal Cognitive Assessment Scores among Individuals with Normal Hearing and Cochlear Implants

OBJECTIVES

The Montreal Cognitive Assessment (MoCA) is a cognitive screening tool that has 4 of 10 test items heavily dependent on auditory input, potentially leaving hearing-impaired (HI) individuals at a disadvantage. Previous work found that HI individuals scored lower than normal-hearing (NH) individuals on the MoCA, potentially attributed to the degraded auditory signals negatively impacting the ability to commit auditory information to memory. However, there is no research comparing how cochlear implant (CI) recipients perform on the MoCA relative to NH and HI individuals. This study aimed to (1) examine the effect of implementing three different hearing-adjusted scoring methods for a group of age-matched CI recipients and NH individuals, (2) determine if there is a difference between the two groups in overall scores and hearing-adjusted scores, and (3) compare scores across our CI and NH data to the published HI data for all scoring methods. We hypothesized that (1) scores for CI recipients would improve with implementation of the hearing-adjusted scoring methods over the original method, (2) CI recipients would score lower than NH participants for both original and adjusted scoring methods, and (3) the difference in scores between NH and CI listeners for both adjusted and unadjusted scores would be greater than that reported in the literature between NH and HI individuals due to the greater severity of hearing loss and relatively poor spectral resolution of CIs.

DESIGN

A total of 94 adults with CIs and 105 adults with NH were initially enrolled. After age-matching the two groups and excluding those who self-identified as NH but failed a hearing screening, a total of 75 CI participants (mean age 61.2 y) and 74 NH participants (mean age 58.8 y) were administered the MoCA. Scores were compared between the NH and CI groups, as well as to published HI data, using the original MoCA scoring method and three alternative scoring methods that excluded various auditory-dependent test items.

RESULTS

MoCA scores improved for all groups when two of the three alternative scoring methods were used, with no significant interaction between scoring method and group. Scores for CI recipients were significantly poorer than those for age-matched NH participants for all scoring methods. CI recipients scored better than the published data for HI individuals; however, the HI group was not age matched to the CI and NH groups.

CONCLUSIONS

MoCA scores are only partly affected by the potentially greater cognitive processing required to interpret degraded auditory signals. Even with the removal of the auditory-dependent items, CI recipients still did not perform as well as the age-matched NH group. Importantly, removing auditory-dependent items significantly and fundamentally alters the test, thereby reducing its sensitivity. This has important limitations for administration and interpretation of the MoCA for people with hearing loss.

Deprescription of aspirin for primary prevention is uncommon at discharge in hospitalised patients with gastrointestinal bleeding

BACKGROUND

Guidelines recommend against aspirin for primary prevention of cardiovascular events in individuals with a history of gastrointestinal bleeding (GIB). It is unknown how often patients on primary prevention aspirin hospitalised with GIB have aspirin discontinued at discharge.

AIMS

To determine the rate of aspirin deprescription and explore long-term outcomes in patients taking aspirin for primary prevention of cardiovascular events.

METHODS

We evaluated all patients hospitalised at Yale-New Haven Hospital between January 2014 and October 2021 with GIB who were on aspirin for primary prevention. Our primary endpoint was the frequency of aspirin deprescription at discharge. Our secondary endpoints were post-discharge hospitalisations for major adverse cardiovascular events (MACE) or GIB. Time-to-event analysis was performed using Kaplan-Meier curves and the log-rank test.

RESULTS

We identified 320 patients with GIB on aspirin for primary prevention: median age was 72 (interquartile range [IQR] 61-81) years and 297 (92.8%) were on aspirin 81 mg daily. Only 25 (9.0%) patients surviving their hospitalisation were deprescribed aspirin at discharge. Among 260 patients with follow-up (median 1103 days; IQR 367-1670), MACE developed post-discharge in 2/25 (8.0%) with aspirin deprescription versus 37/235 (15.7%) with aspirin continuation (log-rank p = 0.28). 0/25 patients with aspirin deprescription had subsequent hospitalisation for GIB versus 17/235 (7.2%) who continued aspirin (log-rank p = 0.13).

CONCLUSIONS

Aspirin for primary cardiovascular prevention was rarely deprescribed at discharge in patients hospitalised with GIB. Processes designed to ensure appropriate deprescription of aspirin are crucial to improve adherence to guidelines, thereby improving the risk-benefit ratio in patients at high risk of subsequent GIB hospitalisations with minimal increased risk of MACE.

Hearing and Vestibular Loss with Misuse of Opioids and Illicit Drugs: A Review of the Literature

BACKGROUND

The purpose of this review was to summarize the literature regarding the effects of opioids and illicit drugs on the auditory and vestibular systems.

METHODS

Data were sourced from published papers reporting hearing loss (HL) and/or vestibular loss (VL) following misuse or overdose of opioids or illicit drugs. Most papers consisted of retrospective single-case reports, with few retrospective reviews or prospective cohort studies. Search terms included variations of HL, VL, opioids, and illicit drugs. Search results yielded 51 articles published between 1976 and 2021. A total of 44 articles were reviewed after excluding studies that were not available in English (n = 3), only described acute effects in healthy cohorts (n = 3) or only described general health aspects in a group on methadone maintenance (n = 1).

RESULTS

Sixteen studies reported ototoxicity from illicit drugs, 27 from prescription opioids, and 1 was unspecified. This review shows that HL associated with amphetamines and cocaine was typically sudden, bilateral, and temporary. HL from cocaine/crack and heroin often presented with greatest losses in the mid-frequency range. HL associated with opioids was typically sudden, bilateral, moderately severe to profound, and in most cases permanent. The literature is sparse regarding VL from illicit drugs and opioids.

CONCLUSION

Practitioners who see patients for sudden or rapidly progressive HL or VL with no apparent cause should inquire about misuse of illicit drugs and opioids, particularly when the HL does not respond to steroid treatment.

Characterizing Polarity Sensitivity in Cochlear Implant Recipients: Demographic Effects and Potential Implications for Estimating Neural Health

Stimulus polarity can affect both physiological and perceptual measures in cochlear-implant recipients. Large differences between polarities for various outcome measures (e.g., eCAP threshold, amplitude, or slope) theoretically reflect poorer neural health, whereas smaller differences reflect better neural health. Therefore, we expect large polarity effects to be correlated with other measures shown to contribute to poor neural health, such as advanced age or prolonged deafness. Our earlier studies using the electrically evoked compound action potential (eCAP) demonstrated differences in polarity effects between users of Cochlear and Advanced Bionics devices when device-specific clinical pulse designs were used. Since the stimuli differed slightly between devices, the first goal of this study was to determine whether small, clinically relevant differences in pulse phase duration (PD) have a significant impact on eCAP polarity effects to potentially explain the device differences observed previously. Polarity effects were quantified as the difference in eCAP thresholds, mean normalized amplitudes, and slope of the amplitude growth function obtained for anodic-first versus cathodic-first biphasic pulses. The results showed that small variations in PD did not explain the observed differences in eCAP polarity effects between devices. Therefore, eCAP polarity sensitivity measures are relatively robust to small differences in pulse parameters. However, it remains unclear what underlies the observed manufacturer differences, which may limit the utility of eCAP polarity sensitivity measures. The second goal was to characterize polarity sensitivity in a large group of CI recipients (65 ears) to relate polarity sensitivity to age and duration of deafness as a proxy for neural health. The same pulse parameters were used for both device groups. The only significant predictors of eCAP polarity effects were age for threshold and amplitude polarity effects for Cochlear recipients and age and duration of deafness for slope for AB recipients. However, three of these four correlations were in the opposite direction of what was expected. These results suggest that eCAP polarity sensitivity measures likely reflect different mechanisms than the effects that age and duration of deafness induce on the peripheral auditory system.

Increased Mortality in Patients Undergoing Inpatient Endoscopy During the Early COVID-19 Pandemic

BACKGROUND AND AIMS

The Coronavirus disease 2019 (COVID-19) pandemic led to the restructuring of most healthcare systems, but the impact on patients undergoing inpatient endoscopic procedures is unknown. We sought to identify factors associated with 30-day mortality among patients undergoing inpatient endoscopy before and during the first wave of the pandemic within an academic tertiary care center.

METHODS

We studied patients who underwent inpatient endoscopic procedures from March 1-May 31 in 2020 (COVID-19 era), the peak of the pandemic's first wave across the care center studied, and in March 1-May 31, 2018 and 2019 (control). Patient demographics and hospitalization/procedure data were compared between groups. Cox regression analyses were conducted to identify factors associated with 30-day mortality.

RESULTS

Inpatient endoscopy volume decreased in 2020 with a higher proportion of urgent procedures, increased proportion of patients receiving blood transfusions, and a 10.1% mortality rate. In 2020, male gender, further distance from hospital, need for intensive care unit (ICU) admission, and procedures conducted outside the endoscopy suite were associated with increased risk of 30-day mortality.

CONCLUSIONS

Patients undergoing endoscopy during the pandemic had higher proportions of ICU admission, more urgent indications, and higher rates of 30-day mortality. Greater proportions of urgent endoscopy cases may be due to hospital restructuring or patient reluctance to seek hospital care during a pandemic. Demographic and procedural characteristics associated with higher mortality risk may be potential areas to improve outcomes during future pandemic hospital restructuring efforts.

The Role of the Gastrointestinal Hospitalist in Optimizing Endoscopic Operations

The gastroenterology (GI) hospitalist model has improved endoscopic operations through improved interdisciplinary coordination, efficiencies introduced in endoscopy unit workflow, and increased patient access to both inpatient and outpatient GI care. The challenges and opportunities associated with a GI hospitalist model and supporting a GI hospitalist team are reviewed, especially in relation to advanced endoscopy. The roles of the GI hospitalist in endoscopy quality measurement and value-based care are also explored. Greater awareness of the GI hospitalist model and tailoring it to fit the needs of the GI practice or endoscopy unit will be key to practice sustainability and growth.

Testing Speech Perception with Cochlear Implants Through Digital Audio Streaming in a Virtual Sound Booth: A Feasibility Study

OBJECTIVE

 For patients who have received cochlear implants (CIs), speech-perception testing requires specialized equipment. This limits locations where these services can be provided, which can introduce barriers for provision of care. Providing speech test stimuli directly to the CI via wireless digital audio streaming (DAS) or wired direct audio input (DAI) allows for testing without the need for a sound booth (SB). A few studies have investigated the use of DAI for testing speech perception in CIs, but none have evaluated DAS. The goal of this study was to compare speech perception testing in CI users via DAS versus a traditional SB to determine if differences exist between the two presentation modes. We also sought to determine whether pre-processing the DAS signal with room acoustics (reverberation and noise floor) to emulate the SB environment would affect performance differences between the SB and DAS.

DESIGN

 In Experiment 1, speech perception was measured for monosyllabic words in quiet and sentences in quiet and in noise. Scores were obtained in a SB and compared to those obtained via DAS with unprocessed speech (DAS-U) for 11 adult CI users (12 ears). In Experiment 2, speech perception was measured for sentences in noise, where both the speech and noise stimuli were pre-processed to emulate the SB environment. Scores were obtained for 11 adult CI users (12 ears) in the SB, via DAS-U, and via DAS with the processed speech (DAS-P).

RESULTS

 For Experiment 1, there was no significant difference between SB and DAS-U conditions for words or sentences in quiet. However, DAS-U scores were significantly better than SB scores for sentences in noise. For Experiment 2, there was no significant difference between the SB and DAS-P conditions. Similar to Experiment 1, DAS-U scores were significantly better than SB or DAS-P scores.

CONCLUSIONS

 By pre-processing the test materials to emulate the noise and reverberation characteristics of a traditional SB, we can account for differences in speech-perception scores between those obtained via DAS and in a SB.

Evidence of Neural Microstructure Abnormalities in Type I Chiari Malformation: Associations Among Fiber Tract Integrity, Pain, and Cognitive Dysfunction

BACKGROUND

Previous case-control investigations of type I Chiari malformation (CMI) have reported cognitive deficits and microstructural white matter abnormalities, as measured by diffusion tensor imaging (DTI). CMI is also typically associated with pain, including occipital headache, but the relationship between pain symptoms and microstructure is not known.

METHODS

Eighteen CMI patients and 18 adult age- and education-matched control participants underwent DTI, were tested using digit symbol coding and digit span tasks, and completed a self-report measure of chronic pain. Tissue microstructure indices were used to examine microstructural abnormalities in CMI as compared with healthy controls. Group differences in DTI parameters were then reassessed after controlling for self-reported pain. Finally, DTI parameters were correlated with performance on the digit symbol coding and digit span tasks within each group.

RESULTS

CMI patients exhibited greater fractional anisotropy (FA), lower radial diffusivity, and lower mean diffusivity in multiple brain regions compared with controls in diffuse white matter regions. Group differences no longer existed after controlling for self-reported pain. A significant correlation between FA and the Repeatable Battery for the Assessment of Neuropsychological Status coding performance was observed for controls but not for the CMI group.

CONCLUSIONS

Diffuse microstructural abnormalities appear to be a feature of CMI, manifesting predominantly as greater FA and less diffusivity on DTI sequences. These white matter changes are associated with the subjective pain experience of CMI patients and may reflect reactivity to neuroinflammatory responses. However, this hypothesis will require further deliberate testing in future studies.

An Electrophysiological Study of Cognitive and Emotion Processing in Type I Chiari Malformation

Type I Chiari malformation (CMI) is a neurological condition in which the cerebellar tonsils descend into the cervical spinal subarachnoid space resulting in cervico-medullary compression. Early case-control investigations have indicated cognitive deficits in the areas of attention, memory, processing speed, and visuospatial function. The present study further examined cognitive and emotional processing deficits associated with CMI using a dual-task paradigm. Nineteen CMI patients were recruited during pre-surgical consultation and 19 matched control participants identified emotional expressions in separate single and asynchronous dual-task designs. To extend earlier behavioral studies of cognitive effects in CMI, we recorded event-related potentials (ERPs) in the dual-task design. Though response times were slower for CMI patients across the two tasks, behavioral and ERP analyses indicated that patients did not differ from matched controls in the ability to allocate attentional resources between the two tasks. P1 ERP component analyses provided no indication of an emotional arousal deficit in our CMI sample while P3 ERP component analyses suggested a CMI-related deficit in emotional regulation. P3 analysis also yielded evidence for a frontalization of neurophysiological activity in CMI patients. Pain and related depression and anxiety factors accounted for CMI deficits in single-task, but not dual-task, response times. Results are consistent with a dysfunctional fronto-parietal attentional network resulting from either the indirect effects of chronic pain or the direct effects of CMI pathophysiology stemming from cervico-medullary compression.

Type I Chiari malformation, RBANS performance, and brain morphology: Connecting the dots on cognition and macrolevel brain structure

BACKGROUND

Idiopathic descent of cerebellar tonsils into the cervical spine in Chiari malformation Type I (CMI) is typically associated with occipital headache. Accumulating evidence from experimental studies suggests cognitive effects of CMI. The aim of the current study was to examine the relationship between cognition and CMI using a battery of standardized neuropsychological and symptom inventory instruments.

METHOD

Eighteen untreated adults with CMI, and 18 gender, age, and education matched healthy controls completed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and standardized measures of pain, mood, and disability. Morphometric measurements of key neural and osseous elements were also obtained from structural brain magnetic resonance images, for correlation with symptom outcomes.

RESULTS

CMI patients exhibited deficits in RBANS attention, immediate memory, delayed memory, and total score. After controlling for pain and associated affective disturbance, the significant group effect for RBANS attention remained. CMI patients also presented seven morphometric differences comprising the cerebellum and posterior cranial fossa compartment that differed from healthy controls, some of which were associated with self-reported pain and disability. Notably, group differences in tonsillar position were associated with self-reported pain, disability, and delayed memory.

CONCLUSION

Adult CMI is associated with domain-specific cognitive change, detectable using a standard clinical instrument. The extent of cognitive impairment is independent of pain or affective symptomatology and may be related to the key pathognomonic feature of the condition. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Internet and Audiology: A Review of the Third International Meeting

PURPOSE

In this introduction, the four members of the scientific committee for the Third International Meeting on Internet and Audiology describe the meeting that took place at the University of Louisville on July 27-28, 2017.

METHOD

This special issue, with a decidedly clinical focus, includes 14 articles that arose from presentations given at the Third International Meeting on Internet and Audiology. All touch upon the theme of innovation as it pertains to teleaudiology and mobile health (mHealth), application of Big Data to audiology, and ethics of internet and telemedicine.

CONCLUSION

Innovations in teleaudiology, mHealth, and Internet-based audiology are developing at a rapid pace and thus research in the field must continue. We invite readers to the next International Meeting on Internet and Audiology that will take place in Southampton, England, June 17-18, 2019.

Techniques for Remotely Programming Children With Cochlear Implants Using Pediatric Audiological Methods via Telepractice

PURPOSE

The purpose of this report is to describe the equipment setup and techniques for successfully testing behavioral thresholds in young children with cochlear implants (CIs) using telepractice. We will also discuss challenges associated with pediatric CI programming that are unique to the use of distance technology, and we will describe ways to overcome those challenges. Last, we will review the results from 2 recent studies specifically targeted toward testing behavioral thresholds in young children with CIs.

METHOD

Conditioned play audiometry or visual reinforcement audiometry was used to measure behavioral thresholds (T levels) for 35 young children with CIs (n = 19 for conditioned play audiometry and n = 16 for visual reinforcement audiometry). Participants were tested in the traditional in-person condition and in the remote condition using an AB-BA study design over 2 visits.

RESULTS

There was no significant difference in T levels between the in-person and remote conditions, indicating that it is feasible to test young children using conventional pediatric testing procedures via remote technology. The primary challenges encountered were in regard to proper camera and video monitor placement at the remote site and the timing of communication between the audiologist and test assistant.

CONCLUSIONS

The results from studies to date suggest that distance technology can be used successfully to program CI sound processors for young children using standard, age-appropriate testing techniques. The alternative of remote testing has substantial implications for reducing time and travel burdens for families, potentially leading to the construction of appropriate maps for young children with CIs in a timelier manner.

Measuring Sound-Processor Thresholds for Pediatric Cochlear Implant Recipients Using Visual Reinforcement Audiometry via Telepractice

PURPOSE

The goal of this study was to test the feasibility of using telepractice for measuring behavioral thresholds (T levels) in young children with cochlear implants (CIs) using visual reinforcement audiometry (VRA). Specifically, we examined whether there were significant differences in T levels, test time, or measurement success rate between in-person and remote test conditions.

METHOD

Data were collected for 17 children, aged 1.1-3.4 years. A within-subject AB-BA (A, in-person; B, remote) study design was used, with data collection typically occurring over 2 visits. T levels were measured during each test session using VRA for one basal, middle, and apical electrode. Two additional outcome measures included test time and response success rate, the latter of which was calculated as the ratio of the number of electrode thresholds successfully measured versus attempted. All 3 outcome measures were compared between the in-person and remote sessions. Last, a parent/caregiver questionnaire was administered at the end of the study to evaluate subjective aspects of remote versus traditional CI programming.

RESULTS

Results showed no significant difference in T levels between in-person and remote test conditions. There were also no significant differences in test time or measurement success rate between the two conditions. The questionnaires indicated that 82% of parents or caregivers would use telepractice for routine CI programming visits some or all of the time if the option was available.

CONCLUSION

Results from this study suggest that telepractice can be used successfully to set T levels for young children with CIs using VRA.

Effect of Stimulus Polarity on Physiological Spread of Excitation in Cochlear Implants

BACKGROUND

Contemporary cochlear implants (CIs) use cathodic-leading, symmetrical, biphasic current pulses, despite a growing body of evidence that suggests anodic-leading pulses may be more effective at stimulating the auditory system. However, since much of this research on humans has used pseudomonophasic pulses or biphasic pulses with unusually long interphase gaps, the effects of stimulus polarity are unclear for clinically relevant (i.e., symmetric biphasic) stimuli.

PURPOSE

The purpose of this study was to examine the effects of stimulus polarity on basic characteristics of physiological spread-of-excitation (SOE) measures obtained with the electrically evoked compound action potential (ECAP) in CI recipients using clinically relevant stimuli.

RESEARCH DESIGN

Using a within-subjects (repeated measures) design, we examined the differences in mean amplitude, peak electrode location, area under the curve, and spatial separation between SOE curves obtained with anodic- and cathodic-leading symmetrical, biphasic pulses.

STUDY SAMPLE

Fifteen CI recipients (ages 13-77) participated in this study. All were users of Cochlear Ltd. devices.

DATA COLLECTION AND ANALYSIS

SOE functions were obtained using the standard forward-masking artifact reduction method. Probe electrodes were 5-18, and they were stimulated at an 8 (of 10) loudness rating ("loud"). Outcome measures (mean amplitude, peak electrode location, curve area, and spatial separation) for each polarity were compared within subjects.

RESULTS

Anodic-leading current pulses produced ECAPs with larger average amplitudes, greater curve area, and less spatial separation between SOE patterns compared with that for cathodic-leading pulses. There was no effect of polarity on peak electrode location.

CONCLUSIONS

These results indicate that for equal current levels, the anodic-leading polarity produces broader excitation patterns compared with cathodic-leading pulses, which reduces the spatial separation between functions. This result is likely due to preferential stimulation of the central axon. Further research is needed to determine whether SOE patterns obtained with anodic-leading pulses better predict pitch discrimination.

Effects of Stimulus Polarity and Artifact Reduction Method on the Electrically Evoked Compound Action Potential

OBJECTIVE

Previous research from our laboratory comparing electrically evoked compound action potential (ECAP) artifact reduction methods has shown larger amplitudes and lower thresholds with cathodic-leading forward masking (CathFM) than with alternating polarity (AltPol). One interpretation of this result is that the anodic-leading phase used with AltPol elicits a less excitatory response (in contrast to results from recent studies with humans), which when averaged with responses to cathodic-leading stimuli, results in smaller amplitudes. Another interpretation is that the latencies of the responses to anodic- and cathodic-leading pulses differ, which when averaged together, result in smaller amplitudes than for either polarity alone due to temporal smearing. The purpose of this study was to separate the effects of stimulus polarity and artifact reduction method to determine the relative effects of each.

DESIGN

This study used a within-subjects design. ECAP growth functions were obtained using CathFM, anodic-leading forward masking (AnodFM), and AltPol for 23 CI recipients (N = 13 Cochlear and N = 10 Advanced Bionics). N1 latency, amplitude, slope of the amplitude growth function, and threshold were compared across methods. Data were analyzed separately for each manufacturer due to inherent differences between devices.

RESULTS

N1 latencies were significantly shorter for AnodFM than for CathFM and AltPol for both Cochlear and Advanced Bionics participants. Amplitudes were larger for AnodFM than for either CathFM or AltPol for Cochlear recipients; amplitude was not significantly different across methods for Advanced Bionics recipients. Slopes were shallowest for CathFM for Cochlear subjects, but were not significantly different among methods for Advanced Bionics subjects. Thresholds with AltPol were significantly higher than both FM methods for Cochlear recipients; there was no difference in threshold across methods for the Advanced Bionics recipients.

CONCLUSIONS

For Cochlear devices, the smaller amplitudes and higher thresholds observed for AltPol seem to be the result of latency differences between polarities. These results suggest that AltPol is not ideal for managing stimulus artifact for ECAP recordings. For the Advanced Bionics group, there were no significant differences among methods for amplitude, slope, or threshold, which suggests that polarity and artifact reduction method have little influence in these devices. We postulate that polarity effects are minimized for symmetrical biphasic pulses that lack an interphase gap, such as those used with Advanced Bionics devices; however, this requires further investigation.

Perceived improvements and challenges following sequential bilateral cochlear implantation in children and adults

OBJECTIVE

Semi-structured interviews were conducted with sequentially implanted bilateral cochlear-implant (biCI) recipients to examine functional aspects of communication that are affected by listening with one versus two CIs.

DESIGN

Participants were 15 adult biCI recipients and parents of 30 children (categorized into three groups by age) with biCIs. All CI users had sequential placement of biCIs with at least six months' experience with the first CI before activation of the second device, and at least three months' experience with both CIs prior to the interview. The parent/paediatric and adult interviews were all conducted by the same examiner. Electronic transcripts of the interview responses were coded for perceived changes or lack thereof in 23 behaviours following biCI. Extent of reported benefit was quantified for each subject within and across these behaviours and at the group level as a function of age.

RESULTS

Most adults and parents of children reported multiple functional changes following biCI use, and changes often translated to enhanced social communication. Nearly all participants were consistent users of biCIs, and were satisfied with their perceived gains in communicating in everyday settings. Most reported ongoing challenges listening in noisy settings. Although many reports on children paralleled those of adults, developmental differences were apparent. Thirteen percent of adults and twenty percent of parents of children in each of the respective groups reported low levels of change.

CONCLUSIONS

Results suggest that many biCI users experience meaningful functional benefits that may be underestimated by traditional outcome measures. We suggest the need to expand measurement approaches to better quantify the nature of these benefits.

What can stimulus polarity and interphase gap tell us about auditory nerve function in cochlear-implant recipients?

Modeling studies suggest that differences in neural responses between polarities might reflect underlying neural health. Specifically, large differences in electrically evoked compound action potential (eCAP) amplitudes and amplitude-growth-function (AGF) slopes between polarities might reflect poorer peripheral neural health, whereas more similar eCAP responses between polarities might reflect better neural health. The interphase gap (IPG) has also been shown to relate to neural survival in animal studies. Specifically, healthy neurons exhibit larger eCAP amplitudes, lower thresholds, and steeper AGF slopes for increasing IPGs. In ears with poorer neural survival, these changes in neural responses are generally less apparent with increasing IPG. The primary goal of this study was to examine the combined effects of stimulus polarity and IPG within and across subjects to determine whether both measures represent similar underlying mechanisms related to neural health. With the exception of one measure in one group of subjects, results showed that polarity and IPG effects were generally not correlated in a systematic or predictable way. This suggests that these two effects might represent somewhat different aspects of neural health, such as differences in site of excitation versus integrative membrane characteristics, for example. Overall, the results from this study suggest that the underlying mechanisms that contribute to polarity and IPG effects in human CI recipients might be difficult to determine from animal models that do not exhibit the same anatomy, variance in etiology, electrode placement, and duration of deafness as humans.

Can we see more Outpatients without More Doctors?

A reduction in the number of return patients attending general cardiology clinics, if achievable without harm, would improve access for newly referred patients. Outpatient clinic letters (525) sent to general practitioners over a threemonth period were reviewed. Simultaneously, physicians’ opinions were collected by questionnaire. A subset of 30 clinic patients who attended three local general practitioners were studied to identify how many were assessed in primary care, and how often, in a six-month period. The hospital records of these patients were reviewed to determine whether information about these visits to the general practitioner was documented in the hospital notes.

From the outpatient clinics the discharge rates were only 26% and the reason for further clinic review was often not clear. The fact that many patients had no intervention or treatment change performed at the clinic (42%) indicates that patients are reviewed to assess symptom change rather than to receive further interventions. The use of fixed times for review appointment (six months or 1 year) suggests that the intervals are determined by habit rather than clinical indication. A high proportion of patients (28/30) were reviewed at least once in primary care by general practitioners between hospital clinic visits and 20/30 were seen three or more times. There was poor documentation of these consultations in the hospital case notes, and so hospital physicians may be unaware that symptoms are under regular review in primary care.

This study suggests that a substantial proportion of current cardiology return outpatients do not require regular outpatient review. However, alternative management demands good communication and exchange of information between secondary and primary care, development of formal written discharge planning in outpatient letters and other forms of follow-up.

Effect of stimulus level on the temporal response properties of the auditory nerve in cochlear implants

Electrically evoked compound action potentials (ECAPs) have been used to examine temporal response patterns of the auditory nerve in cochlear implant (CI) recipients. ECAP responses to individual pulses in a pulse train vary across stimulation rates for individual CI users. For very slow rates, auditory neurons have ample time to discharge, recover, and respond to each pulse in the train. As the pulse rate increases, an alternating ECAP-amplitude pattern occurs. As the stimulation rate increases further, the alternating pattern eventually ceases and the overall ECAP amplitudes are diminished, yielding a relatively stochastic state that presumably reflects a combination of adaptation, desynchronization, and facilitation across fibers. Because CIs operate over a range of current levels in everyday use, it is important to understand auditory-nerve responses to pulse trains over a range of levels. The effect of stimulus level on ECAP temporal response patterns in human CI users has not been well studied. The first goal of this study was to examine the effect of stimulus level on various aspects of ECAP temporal responses to pulse-train stimuli. Because higher stimulus levels yield more synchronous responses and faster recovery, it was hypothesized that: (1) the maximum alternation would occur at slower rates for lower levels and faster rates at higher levels, (2) the alternation depth at its maximum would be smaller for lower levels, (3) the rate that produces a stochastic state ('stochastic rate') would decrease with level, (4) adaptation would be greater for lower levels as a result of slower recovery, and (5) refractory-recovery time constants would be longer (slower) for lower levels, consistent with earlier studies. The second goal of this study was to examine how refractory-recovery time constants relate specifically to maximum alternation and stochastic rate. Data were collected for 12 ears in 10 CI recipients. ECAPs were recorded in response to each of 13 pulses in an equal-amplitude pulse train ranging in rate from 900-3500 pps for three levels (low, medium, high). The results generally supported hypotheses 1-4; there were no significant effects of level on the refractory-recovery time constants (hypothesis 5). When data were pooled across level, there was a significant negative correlation between alternation depth and refractory recovery time. Understanding the effects of stimulus level on auditory-nerve responses may provide further insight into improving the use of objective measures for potentially optimizing speech-processing strategies.

Measuring Sound-Processor Threshold Levels for Pediatric Cochlear Implant Recipients Using Conditioned Play Audiometry via Telepractice

PURPOSE

This study evaluated the use of telepractice for measuring cochlear implant (CI) behavioral threshold (T) levels in children using conditioned play audiometry (CPA). The goals were to determine whether (a) T levels measured via telepractice were not significantly different from those obtained in person, (b) response probability differed between remote and in-person conditions, and (c) the remote visit required more time than the in-person condition.

METHOD

An ABBA design (A, in-person; B, remote) was split across 2 visits. Nineteen children aged 2.6-7.1 years participated. T levels were measured using CPA for 3 electrodes per session. A "hit" rate was calculated to determine whether the likelihood of obtaining responses differed between conditions. Test time was compared across conditions. A questionnaire was administered to assess parent/caregiver attitudes about telepractice.

RESULTS

Results indicated no significant difference in T levels between conditions. Hit rates were not significantly different between in-person and remote conditions (98% vs. 97%, respectively). Test time was similar between conditions. Questionnaire results revealed that 100% of caregivers would use telepractice for CI appointments either some or all of the time.

CONCLUSION

Telepractice is a viable option for routine pediatric programming appointments for children using CPA to set behavioral thresholds.

Effects of stimulus level and rate on psychophysical thresholds for interleaved pulse trains in cochlear implants

This study examined channel interactions using interleaved pulse trains to assess masking and potential facilitative effects in cochlear-implant recipients using clinically relevant stimuli. Psychophysical thresholds were measured for two adjacent mid-array electrodes; one served as the masker and the other as the probe. Two rates representative of those found in present-day strategies were tested: 1700 and 3400 pulses per second per channel. Four masker levels ranging from sub-threshold to loud-but-comfortable were tested. It was hypothesized that low-level maskers would produce facilitative effects, shifting to masking effects at high levels, and that faster rates would yield smaller masking effects due to greater stochastic neural firing patterns. Twenty-nine ears with Cochlear or Advanced Bionics devices were tested. High-level maskers produced more masking than low-level maskers, as expected. Facilitation was not observed for sub-threshold or threshold-level maskers in most cases. High masker levels yielded reduced probe thresholds for two Advanced Bionics subjects. This was partly eliminated with a longer temporal offset between each masker-probe pulse pair, as was used with Cochlear subjects. These findings support the use of temporal gaps between stimulation of subsequent electrodes to reduce channel interactions.

Pediatric Cochlear Implant Mapping Via Telepractice

Several studies have empirically examined the feasibility and outcomes of remote programming for adults with cochlear implants. Results indicate that equivalent programming levels can be obtained in both the remote and in-person conditions, suggesting that distance technology is a viable alternative to traditional in-person programming methods. Young children, however, require different audiological testing methods to obtain the behavioral responses necessary for speech-processor programming. No studies have empirically evaluated the use of remote programming with the behavioral methods specific to testing young children. Further, young children present additional challenges to behavioral testing (e.g., ability to condition or cooperate) that can lead to the need for additional visits beyond those required for regular programming. This paper describes the potential benefits of remote programming over those achieved for adults, and describes the study design and preliminary results from our current study aimed at validating the use of remote processor programming for young children with cochlear implants (CIs).

The value of cardiac MRI versus echocardiography in the pre-operative assessment of patients with Duchenne muscular dystrophy

BACKGROUND/PURPOSE

Duchenne Mmuscular Ddystrophy (DMD) related cardiomyopathy is associated with significant perioperative mortality. Cardiac MRI (CMR) has not previously been systematically evaluated as pre-operative assessment tool for heart function in DMD. Our aim was to establish whether CMR versus echocardiography contributes to pre-operative DMD assessment.

METHODS

Case records were retrospectively reviewed of 35 consecutive DMD boys who underwent evaluation for surgical procedures between 2010 and 2013.

RESULTS

Echocardiography revealed a median left ventricular (LV) shortening fraction (SF) of 29/% (range: 7-44). 37% of boys (13/35) had abnormal SF <25%, 66% (23/35) showed hypokinesia and 26% (9/35) had LV dilatation. CMR revealed a median left ventricular ejection fraction (LVEF) of 52% (range: 27-67%). 57% of boys (20/35) had abnormal LVEF <55%, 71% (25/35) had hypokinesia, and 82% late gadolinium enhancement. Extensive versus minimal late gadolinium enhancement was associated with reduced left ventricular ejection fraction (48% vs 58%; p = 0.003) suggesting more severe cardiomyopathy. Although echocardiography shortening fraction correlated with CMR ejection fraction (rs = 0.67; p < 0.001), three-quarter of echocardiography studies had suboptimal scanning windows and in 26% measurements significantly over- or underestimated left-ventricular function compared to CMR.

CONCLUSION

Our findings clearly demonstrate the added value of CMR versus echocardiography in assessing DMD-cardiomyopathy. Particularly when echocardiographic scanning windows are suboptimal, CMR should be considered to allow accurate pre-operative cardiac assessment.

Pitch ranking, electrode discrimination, and physiological spread of excitation using current steering in cochlear implants

The first objective of this study was to determine whether adaptive pitch-ranking and electrode-discrimination tasks with cochlear-implant (CI) recipients produce similar results for perceiving intermediate "virtual-channel" pitch percepts using current steering. Previous studies have not examined both behavioral tasks in the same subjects with current steering. A second objective was to determine whether a physiological metric of spatial separation using the electrically evoked compound action potential spread-of-excitation (ECAP SOE) function could predict performance in the behavioral tasks. The metric was the separation index (Σ), defined as the difference in normalized amplitudes between two adjacent ECAP SOE functions, summed across all masker electrodes. Eleven CII or 90 K Advanced Bionics (Valencia, CA) recipients were tested using pairs of electrodes from the basal, middle, and apical portions of the electrode array. The behavioral results, expressed as d', showed no significant differences across tasks. There was also no significant effect of electrode region for either task. ECAP Σ was not significantly correlated with pitch ranking or electrode discrimination for any of the electrode regions. Therefore, the ECAP separation index is not sensitive enough to predict perceptual resolution of virtual channels.

The relation between auditory-nerve temporal responses and perceptual rate integration in cochlear implants

The purpose of this study was to examine auditory-nerve temporal response properties and their relation to psychophysical threshold for electrical pulse trains of varying rates ("rate integration"). The primary hypothesis was that better rate integration (steeper slope) would be correlated with smaller decrements in ECAP amplitude as a function of stimulation rate (shallower slope of the amplitude-rate function), reflecting a larger percentage of the neural population contributing more synchronously to each pulse in the train. Data were obtained for 26 ears in 23 cochlear-implant recipients. Electrically evoked compound action potential (ECAP) amplitudes were measured in response to each of 21 pulses in a pulse train for the following rates: 900, 1200, 1800, 2400, and 3500 pps. Psychophysical thresholds were obtained using a 3-interval, forced-choice adaptive procedure for 300-ms pulse trains of the same rates as used for the ECAP measures, which formed the rate-integration function. For each electrode, the slope of the psychophysical rate-integration function was compared to the following ECAP measures: (1) slope of the function comparing average normalized ECAP amplitude across pulses versus stimulation rate ("adaptation"), (2) the rate that produced the maximum alternation depth across the pulse train, and (3) rate at which the alternating pattern ceased (stochastic rate). Results showed no significant relations between the slope of the rate-integration function and any of the ECAP measures when data were collapsed across subjects. However, group data showed that both threshold and average ECAP amplitude decreased with increased stimulus rate, and within-subject analyses showed significant positive correlations between psychophysical thresholds and mean ECAP response amplitudes across the pulse train. These data suggest that ECAP temporal response patterns are complex and further study is required to better understand the relative contributions of adaptation, desynchronization, and firing probabilities of individual neurons that contribute to the aggregate ECAP response.

Pitch ranking, electrode discrimination, and physiological spread-of-excitation using Cochlear's dual-electrode mode

This study compared pitch ranking, electrode discrimination, and electrically evoked compound action potential (ECAP) spatial excitation patterns for adjacent physical electrodes (PEs) and the corresponding dual electrodes (DEs) for newer-generation Cochlear devices (Cochlear Ltd., Macquarie, New South Wales, Australia). The first goal was to determine whether pitch ranking and electrode discrimination yield similar outcomes for PEs and DEs. The second goal was to determine if the amount of spatial separation among ECAP excitation patterns (separation index, Σ) between adjacent PEs and the PE-DE pairs can predict performance on the psychophysical tasks. Using non-adaptive procedures, 13 subjects completed pitch ranking and electrode discrimination for adjacent PEs and the corresponding PE-DE pairs (DE versus each flanking PE) from the basal, middle, and apical electrode regions. Analysis of d' scores indicated that pitch-ranking and electrode-discrimination scores were not significantly different, but rather produced similar levels of performance. As expected, accuracy was significantly better for the PE-PE comparison than either PE-DE comparison. Correlations of the psychophysical versus ECAP Σ measures were positive; however, not all test/region correlations were significant across the array. Thus, the ECAP separation index is not sensitive enough to predict performance on behavioral tasks of pitch ranking or electrode discrimination for adjacent PEs or corresponding DEs.

Effect of ECAP-based choice of stimulation rate on speech-perception performance

OBJECTIVES

The objective determination of an optimal stimulation rate for CI users could save time and take the uncertainty out of choosing a rate based on patient preference. Electrically evoked compound action potential (ECAP) temporal response patterns vary across stimulation rates and cochlear regions, and could be useful in objectively predicting an optimal rate. Given that only one rate of stimulation can be used for current CI devices, we propose two potential ways to investigate whether a rate that produces stochastic ECAP responses (termed stochastic rate) can be used to predict an optimal stimulation rate. The first approach follows that of , which compared performance across three cochlear regions using limited electrode sets. This approach, which has inherent limitations, may provide insight into the effects of region-specific stochastic rates on performance. The second, more direct, approach is to compare speech perception for full-array maps that each uses a stochastic rate from a different region of the cochlea. Using both of these methods in a set of two acute experiments, the goal of the present study was to assess the effects of stochastic rate on speech perception.

DESIGN

Speech-perception stimuli included the Hearing in Noise Test (HINT sentences), Consonant-Nucleus-Consonant (CNC) phonemes, and Iowa Medial Consonants. For Experiment 1, 22 ears in 20 CI recipients were tested in three map conditions (basal-only, middle-only, and apical-only electrode sets) using the subject's daily-use stimulation rate to first explore the level of performance possible with region-specific maps. A one-way repeated-measures analysis of variance (RM ANOVA) was used to examine the effect of electrode region on performance. A subset of nine subjects was tested with three additional maps (basal-only, middle-only, and apical-only electrode sets) using the region-specific stochastic rate, as measured in a previous study. A two-way RM ANOVA was used to assess the effects of electrode region and per-channel stimulation rate on performance for this subgroup. For Experiment 2, the same subset of nine subjects was tested with four full-array maps that each used either the daily-use stimulation rate or one of the stochastic rates. A one-way RM ANOVA was used to examine the effect of stimulation rate on performance.

RESULTS

For Experiment 1, average performance with the daily-use rate and the stochastic rate was significantly better using the middle electrode set for HINT sentences and CNC phonemes. Perception of medial consonants was similar using the basal and middle electrode sets, and both of these were better than consonant perception with the apical region. For the subgroup of subjects tested with both the daily and stochastic rates, results revealed that stimulation rate did not have a significant effect on performance. For Experiment 2, results revealed no significant differences in performance using full-array maps with different stochastic rates or with the daily-use rate.

CONCLUSIONS

Speech-perception scores were higher using the middle electrode set than with the basal or apical sets; however, this may have resulted from less spectral compression for the middle-region map. The effect of using stochastic rate as an optimal stimulation rate requires further investigation. A longer acclimatization period may be more likely to show differences in performance using stochastic rates versus daily-use rates.

ECAP spread of excitation with virtual channels and physical electrodes

The primary goal of this study was to evaluate physiological spatial excitation patterns for stimulation of adjacent physical electrodes and intermediate virtual channels. Two experiments were conducted that utilized electrically evoked compound action potential (ECAP) spread-of-excitation (SOE) functions obtained with the traditional forward-masking subtraction method. These two experiments examined spatial excitation patterns for virtual-channel maskers and probes, respectively. In Experiment 1, ECAP SOE patterns were obtained for maskers applied to physical electrodes and virtual channels to determine whether virtual-channel maskers yield SOE patterns similar to those predicted from physical electrodes. In Experiment 2, spatial separation of SOE functions was compared for two adjacent physical probe electrodes and the intermediate virtual channel to determine the extent to which ECAP SOE patterns for virtual-channel probes are spatially separate from those obtained with physical electrodes. Data were obtained for three electrode regions (basal, middle, apical) for 35 ears implanted with Cochlear (N = 16) or Advanced Bionics (N = 19) devices. Results from Experiment 1 showed no significant difference between predicted and measured ECAP amplitudes for Advanced Bionics subjects. Measured ECAP amplitudes for virtual-channel maskers were significantly larger than the predicted amplitudes for Cochlear subjects; however, the difference was <2 μV and thus is likely not clinically significant. Results from Experiment 2 showed that the probe set in the apical region demonstrated the least amount of spatial separation amongst SOE functions, which may be attributed to more uniform nerve survival patterns, closer electrode spacing, and/or the tapered geometry of the cochlea. As expected, adjacent physical probes demonstrated greater spatial separation than for comparisons between each physical probe and the intermediate virtual channel. Finally, the virtual-channel SOE functions were generally weighted toward the basal electrode in the pair.

The effect of technology and testing environment on speech perception using telehealth with cochlear implant recipients

PURPOSE

In this study, the authors evaluated the effect of remote system and acoustic environment on speech perception via telehealth with cochlear implant recipients.

METHOD

Speech perception was measured in quiet and in noise. Systems evaluated were Polycom visual concert (PVC) and a hybrid presentation system (HPS). Each system was evaluated in a sound-treated booth and in a quiet office.

RESULTS

For speech in quiet, there was a significant effect of environment, with better performance in the sound-treated booth than in the office; there was no effect of system (PVC or HPS). Speech in noise revealed a significant interaction between environment and system. Subjects' performance was poorer for PVC in the office, whereas performance in the sound-treated booth was not significantly different for the two systems. Results from the current study were compared to results for the same group of subjects from an earlier study; these results suggested that poorer performance at remote sites in the previous study was primarily due to environment, not system.

CONCLUSIONS

Speech perception was best when evaluated in a sound-treated booth. HPS was superior for speech in noise in a reverberant environment. Future research should focus on modifications to non-sound-treated environments for telehealth service delivery in rural areas.

Use of telehealth for research and clinical measures in cochlear implant recipients: a validation study

PURPOSE

The goal of this study was to compare clinical and research-based cochlear implant (CI) measures using telehealth versus traditional methods.

METHOD

This prospective study used an ABA design (A = laboratory, B = remote site). All measures were made twice per visit for the purpose of assessing within-session variability. Twenty-nine adult and pediatric CI recipients participated. Measures included electrode impedance, electrically evoked compound action potential thresholds, psychophysical thresholds using an adaptive procedure, map thresholds and upper comfort levels, and speech perception. Subjects completed a questionnaire at the end of the study.

RESULTS

Results for all electrode-specific measures revealed no statistically significant differences between traditional and remote conditions. Speech perception was significantly poorer in the remote condition, which was likely due to the lack of a sound booth. In general, subjects indicated that they would take advantage of telehealth options at least some of the time, if such options were available.

CONCLUSIONS

Results from this study demonstrate that telehealth is a viable option for research and clinical measures. Additional studies are needed to investigate ways to improve speech perception at remote locations that lack sound booths and to validate the use of telehealth for pediatric services (e.g., play audiometry), sound-field threshold testing, and troubleshooting equipment.

Longitudinal functional performance among children with cochlear implants and disabilities: a prospective study using the Pediatric Evaluation of Disability Inventory

OBJECTIVE

Functional outcomes are important in children with cochlear implants (CI) and additional disabilities as studies on auditory skill and speech/language development may not identify functional benefits from implantation. This study sought to measure functional performance skills of young children with developmental disabilities post-CI.

METHODS

Eight children with cognitive disabilities undergoing cochlear implantation were enrolled in a prospective study of language and functional abilities; 6 with 1 year follow-up were included in the analysis. Functional performance was measured using Pediatric Evaluation of Disability Inventory (PEDI), providing standardized (mean: 50) and scaled scores (range: 0-100) of functional domains: Self-Care, Mobility and Social Function. The PEDI was administered pre-implant, 6 and 12 months post-implantation along with language testing at the same intervals.

RESULTS

All children had cognitive disability; 5 also had motor delay. The ages at CI ranged from 13.8 to 134 months. For functional abilities, children did not make significant changes in domain-specific standard scores over 1 year. Children made progress in scaled scores by 1-year post-implant. The largest increase for all domains occurred in the first 6 months (7-11.5 point increase). For language abilities, children made a median 5.5-month increase in receptive language age (p=0.06) and 5-month increase in expressive language age (p=0.03) in the first year post-CI with no change in language quotients. Receptive language level was significantly (p<0.05) associated with increasing scores in the domains of Self-Care and Social Function.

CONCLUSIONS

This is the first study to measure daily functional abilities in children with implants and disabilities using a standardized tool. Although our small group of complex children did not have an increase in standard scores (gap-closing trajectories), they made progress in skill development on scaled scores. Receptive language appears to play a key role in social functioning in this population. Functional assessments are informative for treatment planning and identifying specific areas to target intervention.

Temporal response properties of the auditory nerve: data from human cochlear-implant recipients

The primary goal of this study was to characterize the variability in auditory-nerve temporal response patterns obtained with the electrically evoked compound action potential (ECAP) within and across a relatively large group of cochlear-implant recipients. ECAPs were recorded in response to each of 21 pulses in a pulse train for five rates (900, 1200, 1800, 2400, and 3500 pps) and three cochlear regions (basal, middle, and apical). An alternating amplitude pattern was typically observed across the pulse train for slower rates, reflecting refractory properties of individual nerve fibers. For faster rates, the alternation ceased and overall amplitudes were substantially lower relative to the first pulse in the train, reflecting cross-fiber desynchronization. The following specific parameters were examined: (1) the rate at which the alternating pattern ceased (termed stochastic rate), (2) the alternation depth and the rate at which the maximum alternation occurred, and (3) the average normalized ECAP amplitude across the pulse train (measure of overall adaptation/desynchronization). Data from 29 ears showed that stochastic rates for the group spanned the entire range of rates tested. The majority of subjects (79%) had different stochastic rates across the three cochlear regions. The stochastic rate occurred most frequently at 2400 pps for basal and middle electrodes, and at 3500 pps for apical electrodes. Stimulus level was significantly correlated with stochastic rate, where higher levels yielded faster stochastic rates. The maximum alternation depth averaged 19% of the amplitude for the first pulse. Maximum alternation occurred most often at 1800 pps for basal and apical electrodes, and at 1200 pps for middle electrodes. These differences suggest some independence between alternation depth and stochastic rate. Finally, the overall amount of adaptation or desynchronization ranged from 63% (for 900 pps) to 23% (for 3500 pps) of the amplitude for the first pulse. Differences in temporal response properties across the cochlea within subjects may have implications for developing new speech-processing strategies that employ varied rates across the array.

Evaluating the Feasibility of Using Remote Technology for Cochlear Implants

The use of remote technology to provide cochlear implant services has gained popularity in recent years. This article contains a review of research evaluating the feasibility of remote service delivery for recipients of cochlear implants. To date, published studies have determined that speech-processor programming levels and other objective tests (electrode impedance and electrically evoked compound action potentials) are equivalent to those obtained in the face-to-face condition. Despite these promising findings, speech perception using remote technology has proven to be more challenging. Previous investigations have evaluated speech perception with recipients of cochlear implants using videoconference (Polycom) equipment in nonsound-treated rooms (due to lack of access to audiological sound booths in rural areas). Results have revealed poorer speech perception scores using remote technology compared to face-to-face results. Additionally, it has been shown that Polycom transmission of a speech stimulus does not cause significant compression for adequate evaluation; rather, poorer results are due to testing performed in nonsound-treated environments. Based on the literature, telepractice is a feasible option for cochlear implant service delivery. Barriers to the wide-spread use of remote services for recipients of cochlear implants include a uniform system for the evaluation of speech perception, validation of services for pediatric recipients and initial activations, license reciprocity, and reimbursement for services.

Off label use of devices and drugs in interventional radiology

AIM

To establish how often off-label device and drug use occurs in interventional radiology (IR) in a UK tertiary referral hospital and consider the wider implications for the interventional radiologist.

MATERIALS AND METHODS

Prospective data were collected during interventional procedures for 1 working week in a university hospital. Out-of-hours procedures and procedures outside the department were excluded. Operators were asked to record the drugs and devices used, the indication, and method of use. The instructions for use/summary of product characteristics were then studied for each device/drug used to assess if the use was on or off-label.

RESULTS

During the study period 52 cases were performed and data were available on 26 cases (50%). In 22 of the 26 cases (84%) there was evidence of off-label use of devices or drugs. Off-label use of drugs included treatment of venous malformations with Fibrovein(©) (sodium tetradecyl sulphate), which is licensed for the treatment of varicose veins in the leg, and intra-arterial injection of heparin, which is licensed for intravenous and subcutaneous use. Off-label device use included placing vascular sheaths in the urinary tract, using angiographic catheters to guide wires in the urinary tract, using sheaths for thrombosuction, reshaping of the tip of most guidewires, and using angioplasty balloons to dislodge the arterial plug at fistula thrombectomy.

CONCLUSION

Off-label device and drugs use is common in a UK tertiary hospital IR department and literature suggests this is common in the wider IR community. There are important clinical and legal implications for off-label use for patients and physicians.

Adverse drug reactions: mothers talk

Focal points

Psychophysical and physiological measures of electrical-field interaction in cochlear implants

The primary purpose of this study was to determine whether the electrically evoked compound action potential (ECAP) can be used to predict psychophysical electrical-field interaction patterns obtained with simultaneous stimulation of intracochlear electrodes. The second goal was to determine whether ECAP patterns are affected by recording location because differences might influence the relation between ECAP and psychophysical measures. The third goal was to investigate whether symmetrical threshold shifts are produced with phase inversion of the interaction stimulus. Nine adults with Advanced Bionics cochlear implants participated. ECAP and psychophysical thresholds were obtained for basal, middle, and apical probe electrodes in the presence of a subthreshold interaction stimulus delivered simultaneously to each of seven to eight interaction electrodes per probe. The results showed highly significant correlations between ECAP and psychophysical threshold shifts for all nine subjects, which suggests that the ECAP can adequately predict psychophysical electrical-field interaction patterns for subthreshold stimuli. ECAP thresholds were significantly higher for recordings from the basal (versus apical) side of the probe, which suggests that recording location may affect relations between ECAP and psychophysical measures. Interaction stimulus phase inversion generally produced symmetrical threshold shifts for psychophysical measures but not for half of ECAP measures.

A re-evaluation of the relation between physiological channel interaction and electrode pitch ranking in cochlear implants

Spatial excitation patterns in cochlear implant users can be measured with the electrically evoked compound action potential (ECAP). This study examined whether the relative separation of ECAP excitation patterns for two electrodes was correlated with the ability to discriminate those electrodes on the basis of pitch. Significant correlations were found for nine of the ten subjects. Electrodes with significant relative overlap of ECAP spatial excitation patterns were generally more difficult to distinguish on the basis of pitch. Pitch-ranking ability and overlap of ECAP patterns were both affected by the relative separation between electrodes in each pair. With increased separation between electrodes, pitch ranking improved significantly, and ECAP spatial excitation patterns showed significantly less overlap.

Electrophysiologic channel interaction, electrode pitch ranking, and behavioral threshold in straight versus perimodiolar cochlear implant electrode arrays

The primary goal of this study was to examine electrophysiologic measures of channel interaction, electrode pitch discrimination ability using a pitch-ranking task, and behavioral threshold levels in individuals implanted with a straight electrode array versus a perimodiolar array. It was hypothesized that perimodiolar arrays should yield lower thresholds, less channel interaction as measured with the electrically evoked compound action potential (ECAP), and better electrode pitch-ranking ability. Results from ten adult Nucleus 24 recipients (N=5 straight array, N=5 perimodiolar Contour array) showed no significant difference in threshold between the two electrode designs; however, there was significantly better electrode pitch-ranking ability and less channel interaction as measured with the ECAP for perimodiolar electrodes. Additionally, there was a significant positive correlation between behavioral threshold and width of the ECAP interaction function for Contour group data. There was no significant correlation between behavioral threshold and electrode pitch-ranking ability. These data suggest that electrode design and/or perimodiolar position may reduce physiologic channel interaction in the cochlea and improve electrode pitch discrimination ability; however, this positive finding did not translate into significantly better speech perception ability for Contour subjects.

The relation between electrophysiologic channel interaction and electrode pitch ranking in cochlear implant recipients

The primary goal of this study was to examine the relation between electrophysiologic measures of channel interaction and the ability to discriminate pitch between electrodes in a psychophysical pitch-ranking task. It was hypothesized that cochlear implant recipients should perform better on an electrode pitch-ranking task when using electrodes with less channel interaction as measured with the electrically evoked compound action potential (ECAP). The width of the ECAP channel interaction function was compared with the slope of the pitch-ranking function for 10 adult Nucleus 24 recipients. Results showed no significant correlation between electrode pitch-ranking ability and width of the ECAP channel interaction function for individual subjects or for group data. Additionally, there was no significant correlation between speech perception performance and either pitch-ranking ability or width of the ECAP channel interaction function. These results suggest that the width of the ECAP interaction function may not be an accurate predictor of the ability to discriminate between electrodes on the basis of pitch.

Sensitivity and specificity of averaged electrode voltage measures in cochlear implant recipients

OBJECTIVE

The primary purpose of this study was to evaluate the diagnostic accuracy of averaged electrode voltages (AEVs) for identifying malfunctioning electrodes in cochlear implant users.

DESIGN

AEVs were measured using common ground (N = 33 ears) and monopolar stimulation modes (N = 40 ears) in adult subjects implanted with the Nucleus 24M or Nucleus 24R(CS) cochlear implant. AEV measures were then compared with common ground electrode impedance measures as well as to subjective judgments of electrode sound quality to determine the sensitivity and specificity of AEVs.

RESULTS

Results showed excellent specificity for both modes of AEV testing: 97.9% for common ground and 99.8% for monopolar. Sensitivity for common ground AEV testing was 91.7%; however the sensitivity of monopolar AEVs was very poor, at 7.7%. Monopolar AEVs accurately identified open circuits but missed all short circuits. These results are consistent with the sensitivity of impedance measures made with each of the two stimulation modes.

CONCLUSIONS

Common ground AEVs are more reliable than monopolar AEVs for identifying malfunctioning electrodes.

Pancreatic hamartoma

Pancreatic hamartoma is a rare benign lesion and may be mistaken for a malignancy, as demonstrated by two cases. The first case was a 29-year-old man who presented with a 7-month history of intermittent upper abdominal pain, nausea and vomiting and a 15-kg weight loss. CT and MRI revealed a mass in the head of the pancreas. The second case was a 62-year-old man who presented with a 2-year history of intermittent abdominal pain, vomiting and a 25-kg weight loss. Although positron emission tomography was normal, CT revealed thickening of the duodenal wall and endoluminal ultrasonography revealed a tumour in the head of the pancreas. Both patients recovered from uneventful Kausch-Whipple pancreatoduodenectomy (in the first patient, it was pylorus-preserving), and in each case the histological diagnosis was hamartoma. Pancreatic hamartoma can present with vague, non-specific symptoms which, despite modern diagnostic tools, can be difficult to diagnose. Surgical resection with histopathological examination is required to confirm the diagnosis.