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Myers JS, Kin JM, Billi JE, Burke KG, Harrison RV. Development and validation of an A3 problem-solving assessment tool and self-instructional package for teachers of quality improvement in healthcare. BMJ Qual Saf 2021; 31:287-296. [PMID: 33771908 DOI: 10.1136/bmjqs-2020-012105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 02/20/2021] [Accepted: 03/10/2021] [Indexed: 11/04/2022]
Abstract
PURPOSE A3 problem solving is part of the Lean management approach to quality improvement (QI). However, few tools are available to assess A3 problem-solving skills. The authors sought to develop an assessment tool for problem-solving A3s with an accompanying self-instruction package and to test agreement in assessments made by individuals who teach A3 problem solving. METHODS After reviewing relevant literature, the authors developed an A3 assessment tool and self-instruction package over five improvement cycles. Lean experts and individuals from two institutions with QI proficiency and experience teaching QI provided iterative feedback on the materials. Tests of inter-rater agreement were conducted in cycles 3, 4 and 5. The final assessment tool was tested in a study involving 12 raters assessing 23 items on six A3s that were modified to enable testing a range of scores. RESULTS The intraclass correlation coefficient (ICC) for overall assessment of an A3 (rater's mean on 23 items per A3 compared across 12 raters and 6 A3s) was 0.89 (95% CI 0.75 to 0.98), indicating excellent reliability. For the 20 items with appreciable variation in scores across A3s, ICCs ranged from 0.41 to 0.97, indicating fair to excellent reliability. Raters from two institutions scored items similarly (mean ratings of 2.10 and 2.13, p=0.57). Physicians provided marginally higher ratings than QI professionals (mean ratings of 2.17 and 2.00, p=0.003). Raters averaged completing the self-instruction package in 1.5 hours, then rated six A3s in 2.0 hours. CONCLUSION This study provides evidence of the reliability of a tool to assess healthcare QI project proposals that use the A3 problem-solving approach. The tool also demonstrated evidence of measurement, content and construct validity. QI educators and practitioners can use the free online materials to assess learners' A3s, provide formative and summative feedback on QI project proposals and enhance their teaching.
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Affiliation(s)
- Jennifer S Myers
- Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Jeanne M Kin
- Quality, Michigan Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - John E Billi
- Medicine and Learning Health Sciences, Michigan School of Medicine, University of Michigan, Ann Arbor, Michigan, USA.,Health Management and Policy, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA.,Integrative Systems and Design, College of Engineering, University of Michigan, Ann Arbor, Michigan, USA
| | - Kathleen G Burke
- Biobehavioral Health, University of Pennsylvania School of Nursing, Philadelphia, Pennsylvania, USA.,Leonard Davis Institute of Health Economics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Richard Van Harrison
- Learning Health Sciences, University of Michigan Health System, Ann Arbor, Michigan, USA
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Felt BT, Biermann B, Christner JG, Kochhar P, Harrison RV. Diagnosis and management of ADHD in children. Am Fam Physician 2014; 90:456-464. [PMID: 25369623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is the most common behavioral disorder in children, and the prevalence is increasing. Physicians should evaluate for ADHD in children with behavioral concerns (e.g., inattention, hyperactivity, impulsivity, oppositionality) or poor academic progress using validated assessment tools with observers from several settings (home, school, community) and self-observation, if possible. Physicians who inherit a patient with a previous ADHD diagnosis should review the diagnostic process, and current symptoms and treatment needs. Coexisting conditions (e.g., anxiety, learning, mood, or sleep disorders) should be identified and treated. Behavioral treatments are recommended for preschool-aged children and may be helpful at older ages. Effective behavioral therapies include parent training, classroom management, and peer interventions. Medications are recommended as first-line therapy for older children. Psychostimulants, such as methylphenidate and dextroamphetamine, are most effective for the treatment of core ADHD symptoms and have generally acceptable adverse effect profiles. There are fewer supporting studies for atomoxetine, guanfacine, and clonidine, and they are less effective than the psychostimulants. Height, weight, heart rate, blood pressure, symptoms, mood, and treatment adherence should be recorded at follow-up visits.
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Abstract
Heart failure (HF) often presents as dyspnea either with exertion and/or recumbency. Patients also experience dependent swelling and fatigue. Measurement of the left ventricular ejection fraction (LVEF) identifies HF patients who may respond to pharmacologic therapy and/or electrophysiologic device implantation. Angiotension converting enzyme inhibitors, beta blockers, and aldosterone inhibitors can significantly lower the mortality and morbidity of HF in patients with an LVEF less than 35%. Cardiac defibrillators and biventricular pacemakers can also improve outcomes in selected patients with a decreased LVEF. The authors provide a guide for therapeutic decisions based on the inclusion criteria of the major clinical trials.
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Affiliation(s)
- John M Nicklas
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, 1600 East Medical Center Drive, Ann Arbor, MI 48109-5853, USA.
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Allegro J, Papsin BC, Harrison RV, Campisi P. Acoustic analysis of voice in cochlear implant recipients with post-meningitic hearing loss. Cochlear Implants Int 2009; 11:100-16. [PMID: 19810023 DOI: 10.1002/cii.417] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The objective of this study was to evaluate the critical time period between the onset of sensorineural hearing loss and cochlear implantation with respect to normal voice production in children with post-meningitic hearing loss. Acoustic measures of voice production were obtained from ten paediatric cochlear implant recipients with post-meningitic hearing loss. Acoustic measures were obtained utilising the Multi-Dimensional Voice Program and Computerized Speech Laboratory (Kay Elemetrics Corp.). Measures were based on sustained phonation of the vowel /a/. Acoustic parameters included fundamental frequency, short- and long-term frequency perturbation, and short- and long-term amplitude perturbation. Measures of fundamental frequency and short-term frequency and amplitude perturbation were comparable to values of children with normal hearing. Long-term control of frequency was within normal limits for subjects with a period of auditory deprivation of less than four months. Measures of long-term amplitude perturbation were normal for all patients except those with cochlear ossification. Early restoration of auditory feedback with cochlear implantation, the absence of cochlear ossification, residual aided hearing following meningitis, and auditory-verbal therapy were identified as factors in preserving the long-term control of frequency and amplitude in the setting of post-meningitic hearing loss.
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Affiliation(s)
- J Allegro
- Centre for Paediatric Voice and Laryngeal Function and Department of Communication Disorders, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
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Gordon KA, Papsin BC, Harrison RV. Auditory brainstem activity and development evoked by apical versus basal cochlear implant electrode stimulation in children. Clin Neurophysiol 2007; 118:1671-84. [PMID: 17588811 DOI: 10.1016/j.clinph.2007.04.030] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 04/17/2007] [Accepted: 04/30/2007] [Indexed: 11/21/2022]
Abstract
OBJECTIVE The role of apical versus basal cochlear implant electrode stimulation on central auditory development was examined. We hypothesized that, in children with early onset deafness, auditory development evoked by basal electrode stimulation would differ from that evoked more apically. METHODS Responses of the auditory nerve and brainstem, evoked by an apical and a basal implant electrode, were measured over the first year of cochlear implant use in 50 children with early onset severe to profound deafness who used hearing aids prior to implantation. RESULTS Responses at initial stimulation were of larger amplitude and shorter latency when evoked by the apical electrode. No significant effects of residual hearing or age were found on initial response amplitudes or latencies. With implant use, responses evoked by both electrodes showed decreases in wave and interwave latencies reflecting decreased neural conduction time through the brainstem. Apical versus basal differences persisted with implant experience with one exception; eIII-eV interlatency differences decreased with implant use. CONCLUSIONS Acute stimulation shows prolongation of basally versus apically evoked auditory nerve and brainstem responses in children with severe to profound deafness. Interwave latencies reflecting neural conduction along the caudal and rostral portions of the brainstem decreased over the first year of implant use. Differences in neural conduction times evoked by apical versus basal electrode stimulation persisted in the caudal but not rostral brainstem. SIGNIFICANCE Activity-dependent changes of the auditory brainstem occur in response to both apical and basal cochlear implant electrode stimulation.
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Affiliation(s)
- K A Gordon
- Cochlear Implant Laboratory, the Hospital for Sick Children, and Department of Otolaryngology-Head and Neck Surgery, University of Toronto, Ontario, Canada.
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Satodia P, James A, Mount RJ, Harrison RV. Real Time Olivocochlear Response Audiometry in Neonates. Paediatr Child Health 2003. [DOI: 10.1093/pch/8.suppl_b.17b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Hilton M, Chen J, Kakigi A, Hirakawa H, Mount RJ, Harrison RV. Middle ear instillation of gentamicin and streptomycin in chinchillas: electrophysiological appraisal of selective ototoxicity. Clin Otolaryngol Allied Sci 2002; 27:529-35. [PMID: 12472526 DOI: 10.1046/j.1365-2273.2002.00614.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The purpose of this study was to investigate selective vestibular ototoxicity of gentamicin and streptomycin in the chinchilla model. In total, 10 chinchillas underwent left middle ear instillation of one of three agents: gentamicin, streptomycin and saline. Electrophysiological data (otoacoustic emissions (OAEs), auditory brainstem evoked response (ABRs), and ice-water electronystagmography were recorded before and after instillation. Animals were sacrificed for temporal bone studies using scanning electron microscopy. Morphological changes in the cochlear and vestibular neuroepithelia were correlated with electrophysiological changes. Widespread ipsilateral cochlear and vestibular neuroepithelial injuries were observed and correlated with loss of OAEs, ABRs and ice-water caloric response. This study provides no evidence of selective vestibular ototoxicity of gentamicin or streptomycin. Morphological damage correlates with, but precedes loss of electrophysiological parameters. Chinchillas, like other small mammals, may not be an ideal model for the study of human ototoxicity.
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Affiliation(s)
- M Hilton
- Department of Otorhinolaryngology, Sunnybrook and Women's College Health Science Centre, University of Toronto, Canada.
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Abstract
We investigate a binary partitioning algorithm in the case of a continuous repeated measures outcome. The procedure is based on the use of the likelihood ratio statistic to evaluate the performance of individual splits. The procedure partitions a set of longitudinal data into two mutually exclusive groups based on an optimal split of a continuous prognostic variable. A permutation test is used to assess the level of significance associated with the optimal split, and a bootstrap confidence interval is obtained for the optimal split.
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Affiliation(s)
- M Abdolell
- Population Health Sciences Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, ON, M5G 1X8, Canada.
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Abstract
The aim of this study was to measure contralateral suppression of distortion product otoacoustic emissions (DPOAE) in real time. A total of 10 human subjects were studied with a novel device to record DPOAE without signal time averaging, using digital narrow band pass filtering. Real time DPOAE levels were recorded at 2f1-f2 using primary tone settings of f2/f1 = 1.22 and L1 = 70 dB SPL, L2 = 65 dB SPL, at five values of f2 between 2.2 and 7.7 kHz. An acoustic stimulus was applied intermittently to the contralateral ear to cause DPOAE suppression. Characteristic features of contralateral suppression were identified and distinguished from small spontaneous variations in the real time DPOAE signal. Magnitude of suppression increased with contralateral stimulus intensity. Onset latency of suppression was around 43 ms (31-95 ms). Potential clinical applications are discussed in the light of these findings, including a role in improving the specificity of neonatal hearing screening.
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Affiliation(s)
- A L James
- Auditory Science Laboratory, Department of Otolaryngology and Brain and Behaviour Division, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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10
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Abstract
Inner hair cell lesions to the basal turn of the cochlea effectively result in a partial deafferentation of the auditory system. At the level of the midbrain (central nucleus of inferior colliculus) cochleotopic maps, based on single unit response characteristic frequency, are changed after such deafferentation. When a cochlear lesion is induced in a neonatal animal (chinchilla), the reorganization of the frequency map is more extensive than that resulting from similar deafferentation in the adult subject. Neonatal cochlear lesions result in an over-representation of sound frequencies corresponding to the border of the cochlear lesion, while similar lesions in the adult do not. The results suggest that significant plasticity exists in the auditory midbrain during early post natal development (even in a precocious species, such as chinchilla); however, this plasticity is largely lost in the mature animal. A conceptual model for the frequency map re-wiring is presented.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, The Hospital for Sick Children, and University of Toronto, Canada.
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Harrison RV, Panesar J, El-Hakim H, Abdolell M, Mount RJ, Papsin B. The effects of age of cochlear implantation on speech perception outcomes in prelingually deaf children. Scand Audiol Suppl 2002:73-8. [PMID: 11409781 DOI: 10.1080/010503901750166727] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We have made a retrospective analysis on 70 prelingually deaf children (78% congenital; age range 2-15 years) followed for up to 5 years post-implant during which both closed set speech perception tests (TAC, WIPI) and open set tasks (PBK, GASP) were administered. We used a binary partitioning algorithm to optimally divide our dataset on the basis of age at implantation This technique achieves an optimal split when the heterogeneity of the data is most reduced (maximal drop in deviance). For the closed set speech perception tests (TAC and WIPI) partitioning best divided-out data at age 4.4 years. For the open set tests optimal division was at a higher age of implantation (GASP word, 5.6 years; PBK word, 8.4 years). Using these partitioning values, we have found statistically significant differences between rate of improvement of scores in the younger implanted children compared with those implanted later.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, The Hospital for Sick Children and University of Toronto, Canada.
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12
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Abstract
Utilizing optical imaging we identified and named the arteries that supply the primary auditory cortex in the chinchilla (Chinchilla laniger). The primary auditory cortex is located 2-3 mm caudal to the medial cerebral artery and is supplied by it. Using corrosion casts and scanning electron microscopy we visualized the capillary networks in the auditory cortex and found regional variations in the densities of the capillary bed. We hypothesize that the uneven capillary densities observed in the auditory cortex correspond to neurologically more active areas.
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Affiliation(s)
- J Panesar
- Department of Otolaryngology, University of Toronto, The Hospital for Sick Children, Ont., Canada
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Chavey WE, Blaum CS, Bleske BE, Harrison RV, Kesterson S, Nicklas JM. Guideline for the management of heart failure caused by systolic dysfunction: part II. Treatment. Am Fam Physician 2001; 64:1045-54. [PMID: 11578026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Several large clinical trials conducted over the past decade have shown that pharmacologic interventions can dramatically reduce the morbidity and mortality associated with heart failure. These trials have modified and enhanced the therapeutic paradigm for heart failure and extended treatment goals beyond limiting congestive symptoms of volume overload. Part II of this two-part article presents treatment recommendations for patients with left ventricular systolic dysfunction. The authors recommend that, if tolerated and not contraindicated, the following agents be used in patients with left ventricular systolic dysfunction: an angiotensin-converting enzyme inhibitor in all patients; a beta blocker in all patients except those who have symptoms at rest; and spironolactone in patients who have symptoms at rest or who have had such symptoms within the past six months. Diuretics and digoxin should be reserved, as needed, for symptomatic management of heart failure. Other treatments or treatment programs may be necessary in individual patients.
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El-Hakim H, Levasseur J, Papsin BC, Panesar J, Mount RJ, Stevens D, Harrison RV. Assessment of vocabulary development in children after cochlear implantation. Arch Otolaryngol Head Neck Surg 2001; 127:1053-9. [PMID: 11556852 DOI: 10.1001/archotol.127.9.1053] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVES To assess vocabulary development in children following cochlear implantation and to evaluate the effect of age at implantation on performance. DESIGN Retrospective study (mean follow-up, 3(1/2) years). SETTING Tertiary center. PATIENTS Children with prelingual deafness provided with a cochlear implant between 1988 and 1999, who serially performed the Peabody Picture Vocabulary Test-Revised (60 patients) and the Expressive One-Word Picture Vocabulary Test-Revised (52 patients). The children were subgrouped into those receiving implants at younger than 5 years and at 5 years or older. OUTCOME MEASURES Age-equivalent vocabulary test score and gap index (chronological age minus the age-equivalent score, divided by the chronological age at the time of testing) were calculated. For each test, the following were performed: calculation of rate of change for age-equivalent score; comparison of earliest and latest gap indices means (the cohort and intergroup and intragroup comparison); and multiple regression analysis demonstrating the effect of age at implantation, sex, communication mode, etiology of deafness, and residual hearing on the rate of vocabulary development. RESULTS Expressive and receptive vocabulary development rates were 0.93 and 0.71 (age-equivalent scores per year), respectively. Subgrouped by age at implantation, the children's rates (for both vocabularies) were not statistically different (Peabody Picture Vocabulary Test-Revised, P =.90; Expressive One-Word Picture Vocabulary Test-Revised, P =.23). The global latest gap indices were significantly less than the earliest (Peabody Picture Vocabulary Test-Revised, P =.048; Expressive One-Word Picture Vocabulary Test-Revised, P<.001), indicating an improvement in age-appropriate vocabulary development over time. The age subgroups demonstrated similar results, except for the younger group's receptive gap index. On multiple regression analysis, the significant predictive variables were residual hearing (Expressive One-Word Picture Vocabulary Test-Revised) and male sex and oral communication mode (Peabody Picture Vocabulary Test-Revised). CONCLUSIONS Children with cochlear implants developed their vocabularies at rates that were sufficient to prevent an increase in their gap indices as related to ideal scores at testing. A late age at implantation does not singularly preclude beneficial development of vocabulary.
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Affiliation(s)
- H El-Hakim
- Department of Otolaryngology, The Hospital for Sick Children, Toronto, Ontario.
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Chavey WE, Blaum CS, Bleske BE, Harrison RV, Kesterson S, Nicklas JM. Guideline for the management of heart failure caused by systolic dysfunction: Part I. Guideline development, etiology and diagnosis. Am Fam Physician 2001; 64:769-74. [PMID: 11563568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Over the past decade, the conceptual understanding of heart failure has changed significantly. Several large clinical trials have demonstrated that pharmacologic interventions can dramatically reduce the morbidity and mortality associated with heart failure. These trials have extended the therapeutic paradigm for treating heart failure beyond the goal of limiting congestive symptoms of volume overload. This two-part article presents an evidence-based guideline to assist primary care physicians in evaluating and treating patients with heart failure. Part I describes the new paradigm of heart failure and offers guidance for diagnostic testing. Part II presents a treatment guideline.
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Affiliation(s)
- W E Chavey
- Department of Family Medicine, University of Michigan Medical School, Ann Arbor, USA.
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Gordon KA, Twitchell KA, Papsin BC, Harrison RV. Effect of residual hearing prior to cochlear implantation on speech perception in children. J Otolaryngol 2001; 30:216-23. [PMID: 11771033 DOI: 10.2310/7070.2001.20157] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We examined the impact of residual hearing prior to cochlear implantation on pre- and postimplantation speech perception outcomes in children. Stimulation of the auditory system prior to implantation because of the presence of residual hearing is important for development of the central auditory pathways, whereas, in the absence of such stimulation, the pathways show less development. We hypothesized that children who had some degree of residual hearing preimplantation achieve better speech perception skills than their peers with poorer hearing. From the 133 children followed in our program, we identified 37 children who had an audiometric pure-tone average of better than 95 dB HL in the better ear at any time preimplantation. Psychophysical speech perception measures, the Word Identification Picture Inventory and the Phonetically Balanced Kindergarten list, in these children were compared with those of 96 implanted children who had poorer hearing prior to implantation. Children with more residual hearing showed higher speech perception scores both before implantation and over their first year of implant use than children with poorer hearing, suggesting that there is an advantage in having a greater degree of residual hearing preimplantation. We suggest that this advantage is promoted, in part, by the greater potential for auditory stimulation provided by high-gain hearing aids in children with greater degrees of residual hearing. This advantage appears to be maintained at least over 1 year postimplantation, yet the rates of development of postimplantation speech perception are not different between the groups. We suggest that this may be due to the unique aspects of electrical stimulation from a cochlear implant. Our findings suggest that it is important to minimize the delay of speech perception skills in the preimplantation phase, particularly in children with poor residual hearing. This can be accomplished by implanting children with congenital severe to profound hearing loss at young ages and children with acquired hearing loss soon after the onset. Also, auditory stimulation prior to implantation should be maximized through the consistent use of hearing aids and therapy that emphasizes development of auditory skills.
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Affiliation(s)
- K A Gordon
- Department of Otolaryngology, The Hospital for Sick Children, Toronto, Ontario
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El-Hakim H, Papsin B, Mount RJ, Levasseur J, Panesar J, Stevens D, Harrison RV. Vocabulary acquisition rate after pediatric cochlear implantation and the impact of age at implantation. Int J Pediatr Otorhinolaryngol 2001; 59:187-94. [PMID: 11397500 DOI: 10.1016/s0165-5876(01)00481-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE studies of early vocabulary development after pediatric cochlear implantation show growth rates that approach normality. Do these growth rates continue to rise over time and, therefore, allow a 'catch up' with ideal scores for age, or do they decline after an initial peak. Could age at implantation be a decisive factor in that process? DESIGN retrospective study (mean follow-up 4 years). PATIENTS pre-lingually deaf children implanted between 1988 and1999, who serially performed Peabody Picture Vocabulary Test-Revised (PPVT), (37 patients) and Expressive One-word Picture Vocabulary Test-Revised (EOWPVT), (35 patients). OUTCOME MEASURES the mean rates of age equivalent scores were determined for the whole follow-up period and analyzed further for two post-implant periods (the two halves of follow-up duration of individual patients). After sub-grouping by age at implantation (younger or older than 5 years old), the same analysis was executed for each subgroup. RESULTS the mean EOWPVT rate of the earlier period was higher than that of the later period (1.33 vs. 0.67, P<0.01) and the mean PPVT rate of the earlier period was higher than that of the later period (0.72 vs. 0.5). The latter difference was not statistically significant (P>0.05). Within subgroups by age at implantation, the PPVT mean rates were stable for younger implanted patients (0.56 for both periods) and dropped for the older implanted sub-group (0.87-0.43, P>0.05). The EOWPVT mean rates declined significantly for the older patients group (1.72-0.55, P<0.01) but insignificantly for the younger patients (0.99-0.77, P>0.05). CONCLUSIONS vocabulary acquisition rates decline in the post-implantation period. This is more pronounced with older implanted children and the EOWPVT rates. This information on the time course development of vocabulary after implantation would be valuable in counseling and planning habilitation in addition to candidate selection.
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Affiliation(s)
- H El-Hakim
- Department of Otolaryngology, The Hospital for Sick Children, 555 University Avenue, M5G 1X8, Toronto, Canada.
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Sawada S, Mori N, Mount RJ, Harrison RV. Differential vulnerability of inner and outer hair cell systems to chronic mild hypoxia and glutamate ototoxicity: insights into the cause of auditory neuropathy. J Otolaryngol 2001; 30:106-14. [PMID: 11770952 DOI: 10.2310/7070.2001.20818] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To describe the effects of long-term mild hypoxia and of glutamate poisoning on the functional properties of the cochlea. METHODS Outer hair cell activity was monitored using otoacoustic emissions and cochlear microphonics, and inner hair cell/cochlear afferent function was measured using neural responses (cochlear action potentials or auditory brainstem responses [ABRs]). RESULTS In contrast to the effects of acute anoxia, in which all aspects of cochlear function are simultaneously lost, mild, long-term hypoxia results in a clear differential effect on outer versus inner hair cell systems. During a 2-hour period of mild hypoxia, ABR amplitude and threshold deteriorate significantly, whereas outer hair cell function, as reflected by otoacoustic emissions, shows little or no change. A similar dissociation between inner and outer hair cell function is observed during instillation of glutamate (1-10 mM), where the cochlear microphonic and the otoacoustic emissions are unchanged, whereas cochlear action potential amplitudes are reduced. CONCLUSION These studies demonstrate a difference in vulnerability of inner and outer hair cell systems. The inner hair cell/cochlear afferent system is vulnerable to long-term, mild hypoxia; this may be an etiologic factor in hearing loss of cochlear origin, particularly in high-risk birth infants with auditory neuropathy.
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MESH Headings
- Animals
- Cell Hypoxia
- Chinchilla
- Cochlear Microphonic Potentials
- Glutamic Acid/toxicity
- Hair Cells, Auditory, Inner/drug effects
- Hair Cells, Auditory, Inner/physiopathology
- Hair Cells, Auditory, Outer/drug effects
- Hair Cells, Auditory, Outer/physiopathology
- Microscopy, Electron, Scanning
- Otoacoustic Emissions, Spontaneous
- Time Factors
- Vestibulocochlear Nerve Diseases/etiology
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Affiliation(s)
- S Sawada
- Department of Otolaryngology, The Hospital for Sick Children, University of Toronto, Ontario
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Papsin BC, Gysin C, Picton N, Nedzelski J, Harrison RV. Speech perception outcome measures in prelingually deaf children up to four years after cochlear implantation. Ann Otol Rhinol Laryngol Suppl 2000; 185:38-42. [PMID: 11140997 DOI: 10.1177/0003489400109s1216] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- B C Papsin
- Cochlear Implant Program, the Hospital for Sick Children, Toronto, Canada
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Abstract
Cochlear implants have enabled many children with severe to profound sensorineural hearing loss to develop speech perception skills. However, some children experience few gains while others develop high levels of speech perception. We identified potential factors contributing to poor performance with an implant by studying implanted children who do not develop functional speech perception. Five children were identified as developing no open-set word recognition skills after at least 2 years of implant use. This study group was compared to a randomly selected control group (n=10) and an age-matched control group (n=5). Pre-implant factors were examined using a Graded Profile Analysis and post-implant factors were assessed in a retrospective chart review. A greater number of pre-implant concerns were raised in the study group than in randomized controls (P<0.01). Chronological age and duration of deafness were pre-implant concerns in all study group subjects. A greater number of post-implant concerns were found in the study group than in randomly selected controls (P<0.005). We conclude that while appropriate selection of candidates for cochlear implantation is important in predicting speech perception outcomes, post-implant follow-up is also essential and must include regular monitoring of equipment, monitoring of stimulation levels with use of objective measures of stimulation levels if necessary, and consistent habilitation.
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Affiliation(s)
- K A Gordon
- Department of Otolaryngology and the Cochlear Implant Program, The Hospital for Sick Children, 555 University Avenue, M5G 1X8, Toronto, ON, Canada
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21
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Abstract
In the present study, anatomical projections from the medial geniculate body (MGB) to primary auditory cortex (AI) were investigated in normal adult cats and in animals that were neonatally deafened with the ototoxic drug amikacin. Cochleotopic/tonotopic maps in AI (based on neural response characteristic frequency) were obtained with microelectrode recording techniques, and single or multiple injections of retrograde tracers (horseradish peroxidase and fluorescent dyes) were introduced into AI. The AI maps of the amikacin-treated cats had an abnormal cochleotopic organization, such that deprived cortical areas exhibited an expanded representation of intact regions of the damaged cochlea. However, retrograde tracer injections into different regions of AI produced a normal pattern of labeling in the ventral division of the medial geniculate body (MGBv). In both experimental and control animals, the main mass of labeled thalamic cells was found in the MGBv. Different isofrequency contours in AI receive input from different portions of the MGBv. Thus, cell arrays labeled by anterior AI injections were situated medially in MGBv, and injections into posterior AI labeled MGBv more laterally. Furthermore, the deafened cats did not develop a more divergent thalamocortical projection compared with normal control animals, indicating that an abnormal spread of the thalamocortical afferents across the frequency domain in AI (anterior-posterior axis) is not responsible for the altered cochleotopic map in these neonatally deafened animals. The relatively normal thalamocortical projection pattern suggests that, after neonatal cochlear lesions, the major reorganization of cochleotopic maps occurs at subthalamic levels.
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Affiliation(s)
- S G Stanton
- Auditory Science Laboratory, Otolaryngology/Brain and Behavior, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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Stiles RA, Bahl V, Bernstein SJ, Halman LJ, Harrison RV, Standiford CJ. Improving HEDIS measurement: linking managed care organization and health system ambulatory care data. Qual Manag Health Care 2000; 8:40-8. [PMID: 10787506 DOI: 10.1097/00019514-200008020-00005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This article describes one health system's efforts to improve HEDIS measurement by integrating claims information from its managed care organization with data from its medical center's automated billing, scheduling, and clinical information systems. The authors discuss problems encountered while establishing an integrated measurement process and offer suggestions for others considering such an approach.
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Affiliation(s)
- R A Stiles
- University of Michigan Health System in Ann Arbor, USA
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Kakigi A, Hirakawa H, Harel N, Mount RJ, Harrison RV. Tonotopic mapping in auditory cortex of the adult chinchilla with amikacin-induced cochlear lesions. Audiology 2000; 39:153-60. [PMID: 10905401 DOI: 10.3109/00206090009073068] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We have found a reorganization of tonotopic maps (based on neuron response thresholds) in primary auditory cortex of the adult chinchilla after amikacin-induced basal cochlear lesions. We find an over-representation of a frequency that corresponds to the border area of the cochlear lesion. The reorganization observed is similar in extent to that previously seen in a developmental model. The properties of neurons within the over-represented area were investigated in order to determine whether their responses originated from a common input (an indication of true plasticity) or represented only the result of truncating the activity of the sensory epithelium ("pseudo-plasticity"). Some aspects of our data fit with a true plasticity model and indicate the potential for the deafferented cortex of the mature cortex to regain connections with the surviving sensory epithelium.
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Affiliation(s)
- A Kakigi
- Department of Otolaryngology, The Hospital for Sick Children, University of Toronto, Ontario, Canada
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24
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Harel N, Mori N, Sawada S, Mount RJ, Harrison RV. Three distinct auditory areas of cortex (AI, AII, and AAF) defined by optical imaging of intrinsic signals. Neuroimage 2000; 11:302-12. [PMID: 10725186 DOI: 10.1006/nimg.1999.0537] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using pure-tone sound stimulation, three separate auditory areas are revealed by optical imaging of intrinsic signals in the temporal cortex of the chinchilla (Chinchilla laniger). These areas correlate with primary auditory cortex (AI) and two secondary areas, AII and the anterior auditory field (AAF). We have distinguished AI on the basis of concurrent single-unit electrophysiological recording; neurons within the AI intrinsic signal region have short (<15 ms) onset-response latencies compared with neurons recorded in AII and the AAF. Within AI, AII, and AAF we have been able to define cochleotopic or tonotopic organization from the differences in intrinsic signal areas evoked by pure tones at octave-spaced frequencies from 500 Hz to 16 kHz. The maps in AI and AII are arranged orthogonal to each other.
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Affiliation(s)
- N Harel
- Auditory Science Laboratory, Brain and Behaviour/Otolaryngology, Toronto, Ontario, M5G 1X8, Canada
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25
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Abstract
We used an optical technique to study haemodynamic changes associated with acoustically driven activity in auditory cortex of the chinchilla. Such changes are first detectable c. 0.5 s after stimulation, peak at 2-3 s, and decay within a further 3-6 s. This intrinsic signal imaging reveals activity in separate cortical areas, including primary auditory cortex (AI), secondary auditory cortex (AII) and an anterior auditory field (AAF). We have measured the timing of haemodynamics associated with each area, and find that AI has a different time course from AII and AAF; its haemodynamic change recovers more rapidly. We also show that within AI and AII, place specific activity related to acoustic stimulus frequency can be resolved by this optical imaging method. Our results show the close association between blood flow change and the local metabolic demands of neural activity. The data provide information about the potential of other functional imaging methods (e.g. PET, fMRI) which rely on activity related haemodynamic events.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, Hospital for Sick Children, University of Toronto, Ontario, Canada
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Sonnad SS, Harrison RV, Standiford CJ, Bernstein SJ. Issues in the development, dissemination, and effect of an evidence-based guideline for managing sore throat in adults. Jt Comm J Qual Improv 1999; 25:630-40. [PMID: 10605653 DOI: 10.1016/s1070-3241(16)30477-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND In October 1995 the University of Michigan Healthcare System initiated a program to develop and implement guidelines for primary care in an effort to improve the quality and cost-effectiveness of care for common conditions associated with wide variations in clinical practice. One of these conditions was Group A beta-hemolytic streptococcus (GABHS), present in 5% to 20% of adults complaining of sore throat. METHODS A draft guideline was developed on the basis of a theoretical model of sore throat management, local data, and research evidence. The guideline was revised to reflect physicians' beliefs and practices regarding sore throat management. Guideline recommendations depended only on the number of clinical signs experienced by the patient and included testing only if it was likely to provide additional information about the probability of GABHS. Data on pre- and postdissemination data on patients presenting with sore throat were collected. RESULTS When physicians believed testing or antibiotics were unnecessary, only 7% of patients demanded screening and only 6% of patients wanted antibiotics. Physician beliefs about a patient's need for testing agreed with guideline recommendations in 63% of patients both before and after guideline dissemination. DISCUSSION Disseminating locally modified, evidence-based guidelines may not be sufficient to produce practice changes. If the guideline had been followed, the amount of testing would have been reduced by 17% and the appropriateness of testing improved for 32% of sore throat patients. The results indicate the need for implementation efforts that go beyond presenting evidence, even when that evidence is from both the literature and the local practice setting.
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Affiliation(s)
- S S Sonnad
- Consortium for Health Outcomes, Innovation, and Cost-Effectiveness Studies, University of Michigan, Ann Arbor 48109-0331, USA.
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27
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Chen JM, Kakigi A, Hirakawa H, Mount RJ, Harrison RV. Middle ear instillation of gentamicin and streptomycin in chinchillas: morphologic appraisal of selective ototoxicity. J Otolaryngol 1999; 28:121-8. [PMID: 10410341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
OBJECTIVE To determine selective cochlear and vestibular ototoxicity of two aminoglycoside antibiotics (gentamicin and streptomycin) in the chinchilla model. Middle ear application of these agents mirrors the clinical practice of chemical vestibular ablation used in Meniere's disease. BACKGROUND Middle ear instillation of gentamicin or streptomycin has become a popular form of vestibular ablative treatment for disabling Meniere's disease. The vestibular selectivity of these two drugs applied in this fashion has clinical support but is not fully established in humans. Our understanding in this regard has largely been limited to animal models exposed to systemic infusion of aminoglycosides. METHOD Ten chinchillas underwent left middle ear instillation of one of three agents using variable dosing schedules: gentamicin (n = 6), streptomycin (n = 2), and saline (n = 2) as control. Animals were sacrificed for temporal bone studies using scanning electron microscopy. Morphologic changes in the cochlear and vestibular neuroepithelia were identified. RESULTS Widespread cochlear and vestibular neuroepithelial injuries were observed with both gentamicin and streptomycin. Contralateral ototoxicity was variable and not related to the total dose of drug delivered. The effect of these two aminoglycosides on the dark cells of the vestibular system appeared negligible. CONCLUSION We were unable to confirm the selective damage of vestibular end-organ in the chinchilla by either gentamicin or streptomycin, a phenomenon that is generally perceived to occur in humans. Chinchillas, like other small mammals, may not be an ideal model for the study of human ototoxicity.
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Affiliation(s)
- J M Chen
- Department of Otolaryngology, University of Toronto, Ontario
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28
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Raveh E, Mount RJ, Harrison RV. Increased otoacoustic-emission amplitude secondary to cochlear lesions. J Otolaryngol 1998; 27:354-60. [PMID: 9857322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
OBJECTIVE The measurements of transient evoked otoacoustic emissions and distortion-product otoacoustic emissions are being used increasingly, both as an objective hearing test clinically, and as a research tool to investigate the micromechanical aspects of cochlear function. We hypothesized that localized damage in the apical or middle cochlear turns may have an influence on the micromechanics and the function of adjacent, apparently normal cochlea. For that purpose, we used an animal model of localized apical and middle-turn cochlear lesions. METHOD Extent of damage was assessed by scanning electron microscopy and the function of the damaged cochlea by change in the otoacoustic emission (OAE) levels. RESULTS We found that localized damage to the apical or middle turn may be accompanied by an increase in OAE measured from adjacent apparently normal cochlea. CONCLUSION Explanations to this phenomenon are suggested, and possible clinical associations such as to Meniere's disease and to sudden hearing loss are reviewed.
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MESH Headings
- Animals
- Auditory Perception/physiology
- Chinchilla
- Cochlea/injuries
- Cochlea/pathology
- Cochlea/physiopathology
- Cochlear Diseases/pathology
- Cochlear Diseases/physiopathology
- Cochlear Microphonic Potentials/physiology
- Disease Models, Animal
- Evoked Potentials, Auditory/physiology
- Hair Cells, Auditory, Inner/pathology
- Hair Cells, Auditory, Inner/physiopathology
- Hair Cells, Auditory, Outer/pathology
- Hair Cells, Auditory, Outer/physiopathology
- Hearing/physiology
- Hearing Loss, Sudden/physiopathology
- Meniere Disease/physiopathology
- Microscopy, Electron, Scanning
- Otoacoustic Emissions, Spontaneous/physiology
- Reaction Time
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Affiliation(s)
- E Raveh
- Department of Otolaryngology, Hospital for Sick Children, University of Toronto, Ontario
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29
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Harrison RV, Ibrahim D, Mount RJ. Plasticity of tonotopic maps in auditory midbrain following partial cochlear damage in the developing chinchilla. Exp Brain Res 1998; 123:449-60. [PMID: 9870604 DOI: 10.1007/s002210050589] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
There is substantial reorganization of the midbrain (inferior colliculus) tonotopic map following neonatally induced partial cochlear lesions in the chinchilla. The most obvious feature of this remapping is a large "iso-frequency" region in the ventral sector of the central nucleus of inferior colliculus (ICC). Neurons in this region exhibit similar threshold and tuning properties, with a common characteristic frequency which corresponds to the high-frequency audiometric cutoff. This overrepresented frequency range also corresponds to the high-frequency border of the cochlear lesion. Alterations to the tonotopic map corresponding to lower frequencies, in more dorsal regions of ICC, depend on the extent and degree of the cochlear lesion. When there is minimal damage to apical (low-frequency) cochlear areas, the dorsal ICC has relatively normal frequency representations. With more extensive apical cochlear lesions there is a corresponding disruption of ICC tonotopic representation of the low frequencies. We conclude that the tonotopic map within the ICC can become (re)organized postnatally according to the abnormal pattern of neural activity from the auditory periphery. Similar reorganization can be expected to occur in human infants with a partial cochlear hearing loss from birth.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, Hospital for Sick Children, Toronto, Canada.
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30
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Harrison RV, Cullen JR, Takeno S, Mount RJ. The neonatal chinchilla cochlea: morphological and functional study. Scanning Microsc 1998; 10:889-94. [PMID: 9813648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The developmental time scale of the cochlea varies from species to species. We investigate here the condition of the neonatal cochlea in the chinchilla, a species increasingly used in auditory research. We have examined the morphology of cochlear hair cells using scanning microscopy, and the development of auditory function during the first postnatal month by monitoring auditory brainstem evoked responses (ABR). We find that although there were some outer hair cell kinocilia present in middle and apical areas, the hair cells otherwise were mature at 24 hours after birth. Furthermore, cochlear auditory thresholds are adult-like at birth. However, whilst there was little change in ABR thresholds over one month, there is evidence of continued maturation of the central auditory system as shown by the shortening of the PI-P5 latency from 9.1 ms to 7.7 ms.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, Hospital for Sick Children, Toronto, Canada.
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31
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Kakigi A, Hirakawa H, Harel N, Mount RJ, Harrison RV. Basal cochlear lesions result in increased amplitude of otoacoustic emissions. Audiol Neurootol 1998; 3:361-72. [PMID: 9732130 DOI: 10.1159/000013806] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We have measured the changes in transient otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) during and after ototoxic amikacin treatment in an animal (chinchilla) model. TEOAE and DPOAE were recorded from 6 adult chinchillas over a 6-week time course starting just before a 5-day or 7-day treatment period with amikacin sulphate (400 mg/kg/day, i.m.). After final recordings, cochlear morphology was assessed by scanning electron microscopy. Generally, both DPOAE and TEOAE amplitudes change during and after treatment in a systematic fashion. High-frequency components change first, followed by lower-frequency components. We note that there is often a long latency to the onset of changes in otoacoustic emissions (OAE), and that these changes can continue for weeks after treatment. Most importantly we report that when the basal region of the cochlea is damaged in the frequency region above the OAE recording bandwidth (0.6-6 kHz for TEOAE; 1-6.7 kHz for DPOAE), we often find an increase in OAE amplitudes. More specifically, we note that as a cochlear lesion progresses apically, there is often a transient increase in a frequency-specific OAE before it reduces or is lost. Our results suggest that the increase in OAE amplitudes precedes the expression of detectable cochlear pathology.
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Affiliation(s)
- A Kakigi
- Department of Otolaryngology, Auditory Science Laboratory, University of Toronto and Hospital for Sick Children, Toronto, Canada
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Abstract
OBJECTIVE We describe an animal model of auditory neuropathy in which subjects have extensive, scattered inner haircell loss but with a relatively intact outer haircell population. DESIGN Such a pattern of cochlear haircell damage can be produced in the chinchilla by treatment with the anticancer agent carboplatin. RESULTS In these subjects, otoacoustic emissions (OAEs) and cochlear microphonics remain normal while auditory brain stem evoked potential (ABR) thresholds are significantly elevated. However, in the same subjects, central auditory neurons (in the inferior colliculus) have response thresholds that are considerably lower (by up to 50 dB) than ABR thresholds. These findings parallel the characteristics of auditory neuropathy in humans, in which absent or abnormal ABRs are recorded in patients with only mild to moderate audiometric thresholds and preserved OAEs. CONCLUSIONS We suggest that scattered inner haircell lesions also can result from long-term cochlear hypoxia, and we propose that this is a likely candidate for the etiology of many types of auditory neuropathy in human subjects.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, University of Toronto and The Hospital For Sick Children, Ontario, Canada
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Kakigi A, Hirakawa H, Harel N, Mount RJ, Harrison RV. Comparison of distortion-product and transient evoked otoacoustic emissions with ABR threshold shift in chinchillas with ototoxic damage. Auris Nasus Larynx 1998; 25:223-32. [PMID: 9799987 DOI: 10.1016/s0385-8146(98)00034-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
In this study we compare distortion product otoacoustic emissions (DPOAEs), transient evoked otoacoustic emissions (TEOAEs) and ABR threshold shifts in an animal model (chinchilla) of cochlear hearing loss. Subjects were treated with an aminoglycoside (amikacin) to produce basal cochlear lesions of various degree. DPOAE and TEOAE were measured throughout the treatment period and until hearing thresholds stabilized. ABR thresholds to tone pip stimuli were determined. Cytocochleograms of cochleas were prepared using scanning microscopy. DPOAEs (2f1-f2) were compared to fast Fourier transform (FFT)-analyzed TEOAEs components in the 1-, 2-, and 4-kHz frequency regions. Both types of emission were compared with corresponding ABR thresholds. There was no significant linear correlation between these different measures of cochlear function. Moreover, the amplitudes of DPOAEs reflected smaller regions of cochlear outer hair cell (OHC) damage better than TEOAEs. These results suggest that DPOAEs can be used to more accurately monitor hair cell function at specific hearing locations than TEOAEs.
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MESH Headings
- Amikacin/toxicity
- Animals
- Anti-Bacterial Agents/toxicity
- Audiometry, Evoked Response
- Auditory Threshold/drug effects
- Brain Stem/drug effects
- Chinchilla
- Evoked Potentials, Auditory, Brain Stem/drug effects
- Fourier Analysis
- Hair Cells, Auditory, Outer/drug effects
- Hair Cells, Auditory, Outer/pathology
- Hearing Loss, Sensorineural/chemically induced
- Hearing Loss, Sensorineural/pathology
- Microscopy, Electron, Scanning
- Otoacoustic Emissions, Spontaneous/drug effects
- Signal Processing, Computer-Assisted
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Affiliation(s)
- A Kakigi
- Department of Otolaryngology, Hospital for Sick Children, University of Toronto, Canada
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Takeno S, Wake M, Mount RJ, Harrison RV. Degeneration of spiral ganglion cells in the chinchilla after inner hair cell loss induced by carboplatin. Audiol Neurootol 1998; 3:281-90. [PMID: 9705525 DOI: 10.1159/000013800] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The anticancer drug carboplatin has been used to generate inner hair cell (IHC) lesions in the cochlea of chinchillas. This has provided a valuable model for the study of the relative roles of IHCs and outer hair cells (OHCs). In the present study, we examined the pathological and temporal relationships between the degeneration of the cochlear IHCs and type I spiral ganglion cells (SGCs). A single intravenous dose of 200 mg/m2 carboplatin produced extensive IHC loss with no apparent effect on the OHCs. The auditory brainstem response threshold was significantly elevated by 2 weeks following treatment and remained stable through 12 weeks. Elevated thresholds were well correlated with morphological lesions. On the other hand, the SGC population progressively decreased from 2 to 12 weeks after treatment, to about half of the control density values. A positive correlation existed between the density of SGC and the number of surviving IHCs. These results indicate that selective damage to IHCs causes a distinct loss of SGCs.
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Affiliation(s)
- S Takeno
- Department of Otolaryngology, Hiroshima University, School of Medicine, Hiroshima, Japan
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Abstract
We have assessed sound frequency and intensity responses in primary auditory cortex of the (ketamine) anesthetized chinchilla using optical imaging of intrinsic signals. Temporal cortex was exposed via a 10-mm craniotomy and a windowed chamber was mounted. A 4-second period of gated tones (10 ms rise/fall; 50 ms plateau; 10/s) was presented to the contralateral ear at levels between 0 and 80 dB SPL. The cortical surface was illuminated with 540 nm light and video images captured in 0.5-second bins for 7.5 s (Imager 2001; Optical Imaging). Intrinsic signals were first apparent 0.5-1 s after stimulus onset, and were maximal after 3-4 s; they decayed over several seconds. The cortical area in which intrinsic activity was detected corresponded closely with electrophysiologically defined AI cortex. Intrinsic signals can reliably be detected to stimuli at 30-40 dB SPL, and in general, the area of intrinsic signal activity tends to expand with increasing stimulation level. Using stimulation levels of 80 dB SPL, we show that low-frequency stimuli (0.5-1 kHz) evoke intrinsic signals in anterior areas whilst posterior areas are activated by high-frequency stimuli (e.g. 16 kHz). Thus a low- to high-frequency tonotopic organization is seen along this axis.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, University of Toronto, Canada.
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Abstract
Inner and outer haircells are destroyed within one day following perfusion of the perilymphatic spaces with water, otherwise the structural integrity of the cochlea and the organ of Corti are preserved. This technique is a reliable method to create an acute unilateral deafness model for investigations of auditory function.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, The Hospital for Sick Children, Toronto, Ont., Canada
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Abstract
We have measured transient-evoked and distortion-product otoacoustic emissions (OAEs) in the chinchilla and compared them in the awake and anesthetized animal (using either ketamine or barbiturate agents). We report a significant increase in OAE amplitudes during anesthesia, particularly using ketamine. These effects are most evident for transient-evoked otoacoustic emissions (TEOAEs) as measured in the non-linear mode. Our data support the hypothesis that tonic activity levels in cochlear efferents may be reduced by anesthetic effects, either directly or indirectly (e.g., by general reductions in descending pathway activity), and that reduced cochlear efferent activity will result in the observed increase of OAE amplitudes.
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MESH Headings
- Acoustic Stimulation
- Adjuvants, Anesthesia/administration & dosage
- Anesthesia, General
- Anesthetics, Dissociative/pharmacology
- Animals
- Atropine/administration & dosage
- Barbiturates/pharmacology
- Chinchilla
- Cochlea/drug effects
- Cochlea/innervation
- Evoked Potentials, Auditory, Brain Stem/drug effects
- Evoked Potentials, Auditory, Brain Stem/physiology
- Ketamine/pharmacology
- Neurons, Efferent/drug effects
- Otoacoustic Emissions, Spontaneous/drug effects
- Otoacoustic Emissions, Spontaneous/physiology
- Sodium Chloride/administration & dosage
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Affiliation(s)
- N Harel
- Department of Physiology, University of Toronto, Ontario, Canada
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Abstract
The purpose of this study was to investigate the effect of sectioning the crossed olivocochlear bundle (COCB) on transient evoked otoacoustic emissions (TEOAEs) in anesthetized adult chinchillas. Of particular interest is the role of cochlear efferents to the outer haircells (OHCs) and how they control mechanisms responsible for otoacoustic emissions. Specifically the experiment addressed whether a tonic level of inhibitory control is reduced by COCB section. The nonlinear component of TEOAEs was measured before and after COCB section. Analysis was made of the 1, 2, 3, 4, and 5 kHz frequency components and of the total emission, as quantified by fast Fourier transform (FFT) of the raw (time domain) response. After COCB section, the amplitude of the total response and of the 2, 3, 4, and 5 kHz components increased whereas the amplitude of the 1 kHz component decreased. The results indicate that COCB section reduces inhibitory control of the OHC mechanisms responsible for nonlinear TEOAE generation. It is not clear whether the nerve section eliminates a spontaneous level of activity in COCB efferents, or whether it results in the interruption of a stimulus-evoked feedback loop.
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Affiliation(s)
- A Kakigi
- Department of Otolaryngology, The Hospital for Sick Children, Toronto, Ont., Canada
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Harrison RV, Nedzelski J, Picton N, Papsin BC, Russell S, Margar-Bacal F, Ross D, Papaioannou V, Gordon K, Lockyer L, Ingrams J, Barnett S. The Paediatric Cochlear Implant Program at the Hospital for Sick Children, Toronto. J Otolaryngol 1997; 26:180-7. [PMID: 9176802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Ontario has a province-wide program for provision of cochlear implants. Toronto's Hospital for Sick Children is one of three designated centres that service the paediatric population. This cochlear implant program was established in 1989. Since that time, 37 children (as of May 1996) have been provided with cochlear implants. The program also services Ontario residents who were implanted elsewhere. In the following, we provide a detailed description of the program, including the processes through which children are selected as candidates, the follow-up studies that we carry out, and the roles of various health care professionals involved. We present a demographic survey of our patient population to date, and discuss some of the important issues relating to candidacy.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, Hospital for Sick Children, University of Toronto, Ontario
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Abstract
Using single-unit electrophysiological methods we have mapped sound frequency (or cochleotopic) representation in the auditory cortex of the chinchilla. We describe the surgical approach to expose this area. We report on maps from six subjects and note a considerable variation in shape between individuals. In general, the primary area has a cochleotopic/tonotopic organization in which low frequencies are represented rostrally and higher frequencies caudally. Neurons in the primary area have latency and tuning properties comparable to other mammalian species. A region anterior to the primary (AI) auditory are has a reverse tonotopic map and may be analogous to the anterior auditory field (AAF) reported in other species.
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Affiliation(s)
- R V Harrison
- Department of Otolaryngology, Hospital for Sick Children, Toronto, Ont., Canada.
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41
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Abstract
The anti-cancer drug carboplatin has been used to generate inner hair cell (IHC) lesions in the cochleae of chinchilla. This model has provided a valuable physiological tool for the study of the auditory system, particularly concerning the relative roles of IHCs and outer hair cells (OHCs). We recorded responses to contralateral sound stimuli of single units (SU) in the central nucleus (CN) of the inferior colliculus (IC) from normal and carboplatin treated animals. Normal single unit thresholds and frequency tuning curves (FTCs) were found, despite gross IHC damage within the cochleae of carboplatin treated animals. No evoked afferent responses could be detected in CN regions which represented cochlear loci where total IHC loss had occurred. Normal frequency selectivity in the auditory system is possible with small numbers of surviving IHCs provided OHCs remain normal.
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Affiliation(s)
- M Wake
- Department of Otolaryngology-Head and Neck Surgery, Wolverhampton Hospital, U.K
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42
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Abstract
Otoacoustic emissions (OAEs) are considered to originate from active cochlear processes involving the outer hair cells (OHC). These emissions are suppressed by activity in the efferent olivocochlear bundle (OCB) and following OHC damage caused by noise exposure or ototoxic drugs. Temporary enhancement of OAEs may occur following noise exposure, and permanent enhancement of emissions has been associated with primary afferent dysfunction in the auditory system. This suggests that there are active adaptation processes in the cochlea exist that could potentially compensate for loss of afferent input. We have used the anti-cancer drug carboplatin to induce selective inner hair cell (IHC) lesions in the cochleae of chinchilla and measured the elevation of auditory thresholds that occurred using brainstem responses (ABR). Following carboplatin treatment click evoked otoacoustic emissions (CEOAEs) were amplified from cochlear frequency regions, which demonstrated extensive IHC damage but apparently normal OHCs. These results support the theory that OHCs cells are involved in the production of these cochlear emissions but also provides further evidence that active adaptation processes exist in the cochlea. It is postulated that loss of afferent input reduces the activity in the medial efferent OCB resulting in de-suppression of OHC contractility. Enhanced OHC contractility could then produce amplification of CEOAEs.
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Affiliation(s)
- M Wake
- Department of Otolaryngology-Head and Neck Surgery, Wolverhampton Hospital, U.K
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Harrison RV, Stanton SG, Mount RJ. Effects of chronic cochlear damage on threshold and frequency tuning of neurons in AI auditory cortex. Acta Otolaryngol Suppl 1995; 519:30-5. [PMID: 7610889 DOI: 10.3109/00016489509121867] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We describe the effects of long-term cochlear lesions on the frequency response properties of AI cortical neurons in the cat. Young animals were treated with amikacin to produce bilateral, basal to mid-turn cochlear lesions. After 12-24 months the response properties of single neurons or small unit clusters in primary auditory cortex were recorded in anesthetized animals. Responses to stimulus frequency and intensity were mapped in detail and frequency threshold curves (FTCs) and Q10dB values were derived. Subsequent to recording experiments, scanning electron microscopy of the sensory epithelium was used to characterize the degree and extent of the cochlear damage. In normal control animals, Q10dB values were, on average, lower than those derived by others from cochlear nerve fibre recordings in the same species. In amikacin-treated animals, deterioration was evident in the threshold and tuning properties of cortical neurons, particularly in those cells whose input originated in damaged cochlear regions. Often, neurons associated with 'normal' cochlear areas (as assessed by scanning microscopy) also had poor frequency tuning compared with controls. As an animal model of sensorineural hearing loss, we consider the cat with long-term cochlear lesions to be more appropriate than animals with acute or short-term pathology. We also suggest that in making physiological-psychophysical correlations, neural responses from the central auditory system (e.g. cortex) should perhaps be given more consideration than data derived at the cochlear level.
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Affiliation(s)
- R V Harrison
- Research Institute, Hospital for Sick Children, Toronto, Canada
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Mount RJ, Takeno S, Wake M, Harrison RV. Carboplatin ototoxicity in the chinchilla: lesions of the vestibular sensory epithelium. Acta Otolaryngol Suppl 1995; 519:60-5. [PMID: 7610893 DOI: 10.3109/00016489509121871] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Carboplatin (cis-Diammine-1,1-cyclobutane dicarboxylate platinum II; CBDCA) is a second generation platinum analog with less nephrotoxicity and cochlear ototoxicity than cisplatin, the first generation platinum chemotherapeutic agent. Studies in many animal species have indicated that carboplatin ototoxicity is expressed as damage to cochlear outer hair cells. The lesion is similar, though less severe, than that resulting from cisplatin intoxication. Recent investigations by our laboratory have demonstrated a species-specific ototoxicity of carboplatin in the chinchilla cochlea. Contrary to other animal models, the inner hair cells are the focus of damage; the outer hair cells often sustain little or no damage. Clinical evidence points to vestibular dysfunction in some patients treated with platinum-containing anti-tumoural agents. However, no morphological studies have shown degeneration of the sensory cells in the vestibular labyrinth resulting from carboplatin treatment. The objective of the present study was to determine whether, in view of its unique toxicity in the chinchilla, carboplatin has any toxic effect on the vestibular end organs. Preliminary investigations of the vestibule by light and scanning electron microscopy indicate that sensory cell cilia became exfoliated or deformed in the crista, utricle and in one instance in the saccule. In general the pattern of damage is similar to that caused by other known ototoxic agents including aminoglycosides and cisplatin.
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Affiliation(s)
- R J Mount
- Department of Otolaryngology, Hospital for Sick Children, Toronto, Ontario, Canada
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Macdonald MR, Harrison RV, Wake M, Bliss B, Macdonald RE. Ototoxicity of carboplatin: comparing animal and clinical models at the Hospital for Sick Children. J Otolaryngol 1994; 23:151-9. [PMID: 8064951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Carboplatin was introduced to the paediatric population as an alternative chemotherapeutic agent in the management of various malignant neoplasms, including sarcomas of the head and neck, in the hope that it would have fewer side effects than pre-existing agents. While many investigators have considered the ototoxicity of this drug only incidentally, others have presumed it to be of negligible importance. A recent animal model of its use has demonstrated damage to the inner hair cells of the cochlea, particularly at the basal turn, with a corresponding high incidence of hearing loss. Similarly, 11 of 22 patients who received this agent at the Hospital for Sick Children over the past 2 years demonstrated a sensorineural hearing loss in the 4 to 12 kHz range. This complication occurred as early as after the first dose and was generally progressively worse with subsequent doses. Consequently, we recommend careful audiologic monitoring of children receiving this agent.
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Affiliation(s)
- M R Macdonald
- Department of Otolaryngology, Hospital for Sick Children, Toronto, Ontario
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46
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Abstract
The ototoxicity of carboplatin, a second generation anti-cancer agent, was examined using the chinchilla as an animal model. In animals treated with a clinical therapeutic dose (400 mg/m2), the dominant degenerative change is to inner hair cells (IHCs). This is in sharp contrast to most other ototoxic agents, which damage primarily the outer hair cells (OHCs). Functional changes to the cochlea have been evaluated in carboplatin treated subjects by recording cochlear action potentials (CAP) and cochlear microphonics (CM); cochlear lesions were evaluated using scanning electron microscopy. In carboplatin treated animals, CAP thresholds to tone-pip stimuli were elevated in proportion to IHC damage in corresponding cochlear regions. In contrast, CM amplitudes and 'thresholds' remained close to normal in most cases, reflecting the preservation of OHCs in the basal turn. These results indicate a high degree of independence between the inner and outer hair cell systems in the cochlear transduction mechanism. We suggest that this species-specific preparation with selective IHC loss will provide a valuable tool for studying, separately, the role of OHCs in both afferent and efferent cochlear function.
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Affiliation(s)
- S Takeno
- Department of Otolaryngology, Hospital for Sick Children, Toronto, Ontario, Canada
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Takeno S, Harrison RV, Mount RJ, Wake M, Harada Y. Induction of selective inner hair cell damage by carboplatin. Scanning Microsc 1994; 8:97-106. [PMID: 7973504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Carboplatin (diammine [1,1 cyclobutane dicarboxylato (2)-0,0'] platinum) is an anti-cancer agent which can be toxic to the inner ear. We have explored the nature of this ototoxicity in the chinchilla. In this species, initial degenerative changes appear to be restricted to the inner hair cell (IHC) regions of the organ of Corti. This finding is intriguing and unusual since all other known ototoxic drugs, such as aminoglycosides, are predominantly associated with outer hair cell damage. In the present study, the mechanism of ototoxicity was investigated by comparing two different routes of carboplatin administration. Carboplatin was administered either intravenously (i.v.) or intraperitoneally (i.p.). The mode of administration influenced electrophysiological and morphological changes. Hearing thresholds were elevated in the i.v. group significantly more than in the i.p. group at all tested frequencies. The degree of hair cell damage was evaluated by scanning electron microscopy at four frequency regions in each cochlea. IHC damage in the i.v. group was significantly more severe than in the i.p. group. Carboplatin effects on a different species, the guinea pig, were also determined to clarify interspecies differences. In the guinea pig, outer hair cell damage occurred sporadically and inner hair cells remained intact. In contrast, chinchilla inner hair cells are susceptible to the ototoxic effects of carboplatin. The degree of hair cell damage appears to be dependent on the peak level of carboplatin rather than on the total dose. This animal model provides a new tool for the investigation of inner and outer hair cell function.
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MESH Headings
- Animals
- Carboplatin/administration & dosage
- Carboplatin/toxicity
- Chinchilla
- Electrophysiology
- Evoked Potentials, Auditory, Brain Stem
- Guinea Pigs
- Hair Cells, Auditory, Inner/drug effects
- Hair Cells, Auditory, Inner/physiopathology
- Hair Cells, Auditory, Inner/ultrastructure
- Hearing/physiology
- Injections, Intraperitoneal
- Injections, Intravenous
- Microscopy, Electron, Scanning
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Affiliation(s)
- S Takeno
- Department of Otolaryngology, Hospital for Sick Children, Toronto, Canada
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48
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Harrison RV, Stross JK. Requirements for speakers at "promotional" educational activities versus independent CME activities. Acad Med 1993; 68:841-842. [PMID: 8216651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Nagasawa A, Harrison RV, Mount RJ, Harada Y. Three-dimensional cytoskeletal structures of the chinchilla organ of Corti: scanning electron microscopy application of the polyethylene glycol method. Scanning Microsc 1993; 7:897-906. [PMID: 8146617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We describe the application of a polyethylene glycol (PEG) embedding technique to examine the sensory and supporting structures of the inner ear. The chinchilla organ of Corti was exposed by cracking PEG embedded cochleas. A range of PEG molecular weights (2000-8000) were utilized; PEG 2000, with a melting point of 57 degrees C was preferred. After removal of the PEG, the three-dimensional aspects of intracellular structures were observed using scanning electron microscopy. Filamentous elements in the hair cell cuticular plate and in the supporting cells were clearly observed, as was the meshwork of cross-linked actin filaments in the cuticular portion of sensory hair cells. Microtubule and microfilament alignment patterns in pillar and Deiters cells were also clearly demonstrated. Characteristic structures in the outer hair cell synaptic region, such as the post-synaptic cistern and synaptic body, were well preserved using the PEG method.
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Affiliation(s)
- A Nagasawa
- Department of Otolaryngology, University of Toronto, Canada
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Edwards JR, Harrison RV. Job demands and worker health: three-dimensional reexamination of the relationship between person-environment fit and strain. J Appl Psychol 1993; 78:628-48. [PMID: 8407706 DOI: 10.1037/0021-9010.78.4.628] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The most influential study of the person-environment (P-E) fit approach to stress was conducted by J. R. P. French, R. D. Caplan, and R. V. Harrison (1982). Unfortunately, this study operationalized fit using various transformations of difference scores, thereby introducing numerous substantive and methodological problems. In the present study, the authors reanalyze data from French et al., using a procedure described by J. R. Edwards (in press) that avoids problems with difference scores and captures the underlying three-dimensional relationship between E, P, and strain. Results resolve ambiguities in the French et al. findings and identify relationships between E, P, and strain that, although consistent with P-E fit theory, cannot be adequately represented by fit measures such as those used by French et al. Implications for P-E fit research are discussed.
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Affiliation(s)
- J R Edwards
- Darden Graduate School of Business Administration, University of Virginia
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