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1.
J Int Adv Otol ; 15(3): 352-357, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31846911

RESUMO

OBJECTIVES: Jervell and Lange-Nielsen syndrome is a rare autosomal recessive disease characterized by congenital sensorineural deafness and significant QT interval prolongation. Aims were to study the prevalence of long QT in congenital hearing loss, complications encountered, outcomes by Categories of auditory Performance (CAP) scores and Speech Intelligibility Rating (SIR) scores and to create an algorithm with precautions to be followed in Long QT children. MATERIALS AND METHODS: Study was done at Auditory implant center at a tertiary referral care ENT hospital which includes 41 paediatric patients who were diagnosed to have Long QT during preoperative assessment and underwent cochlear implantation. A standard Protocol was followed in all candidates which includes comprehensive targeted history and investigations, preoperative and intraoperative precautions, and the findings were recorded. RESULTS: Preoperative prophylactic Beta blockers, avoiding sympathetic stimulation and drugs prolonging QT interval with rational use of Magnesium Sulphate and standby of defibrillator were the standard precautions practised. Fatal Arrhythmias were encountered intra-operatively in five patients which was treated with cardiac pacing. Cardiac monitoring was done intraoperatively and during switch-on. Significant improvement in CAP and SIR scores were observed at 3 and 6 months when compared to their base line values. CONCLUSION: With special attention to preoperative evaluation, appropriate intraoperative precautions and monitoring, judicious surgical planning and post surgical follow-up cochlear implantation may be performed safely in patients with JLNS with good postoperative results allowing for improved audition.


Assuntos
Implante Coclear/métodos , Surdez/cirurgia , Perda Auditiva Neurossensorial/cirurgia , Síndrome de Jervell-Lange Nielsen/cirurgia , Percepção Auditiva , Pré-Escolar , Surdez/congênito , Surdez/fisiopatologia , Feminino , Perda Auditiva Neurossensorial/congênito , Perda Auditiva Neurossensorial/fisiopatologia , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Síndrome de Jervell-Lange Nielsen/fisiopatologia , Masculino , Estudos Prospectivos , Estudos Retrospectivos , Inteligibilidade da Fala , Resultado do Tratamento
2.
Int Heart J ; 60(5): 1206-1210, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31484877

RESUMO

A 7-year-old female suffering from syncope attacks and deafness was genetically diagnosed with Jervell and Lange-Nielsen syndrome (JLNS). A transvenous-designed shock lead and implantable cardioverter-defibrillator (ICD) were atypically implanted subcutaneously, because the patient's body was small. Six years after implantation, we confirmed the patient's eligibility for a subcutaneous ICD (S-ICD) based on electrocardiogram screening. The implanted ICD system was replaced with a new standard S-ICD system. Implantation of the S-ICD may be considered a reliable and safe option in young patients with JLNS, even if their electrocardiograms show remarkable prolongation of the QT interval and T-wave alternans.


Assuntos
Desfibriladores Implantáveis/efeitos adversos , Eletrocardiografia/métodos , Síndrome de Jervell-Lange Nielsen/diagnóstico , Síndrome de Jervell-Lange Nielsen/terapia , Canal de Potássio KCNQ1/genética , Criança , Remoção de Dispositivo/métodos , Feminino , Seguimentos , Predisposição Genética para Doença , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Linhagem , Retratamento , Síncope/diagnóstico , Síncope/etiologia , Síncope/terapia , Fatores de Tempo , Resultado do Tratamento
3.
Artigo em Chinês | MEDLINE | ID: mdl-31446697

RESUMO

Summary Jervell and Lange-Nielsen syndrome(JLNS) is an autosomal recessive hereditary disease characterized by congenital severe sensorineural hearing loss in both ears and severe arrhythmias with QT interval prolongation. Children with JLNS often exhibit sensorineural hearing loss and are easily misdiagnosed as non-syndromic hearing loss before attack of cardiac event. When a cochlear implant is performed, a fatal arrhythmia is likely to occur during the perioperative period, which seriously threatens the life of the child. It is currently found that the pathogenic genes of JLNS are mainly KCNQ1 and KCNE1. This article reviews the clinical manifestations, pathogenic genes, diagnosis and differential diagnosis, intervention measures of JLNS to further draw the attention to the disease, reduce misdiagnosis, improve the survival rate and quality of life of children with JLNS.


Assuntos
Arritmias Cardíacas/patologia , Surdez , Síndrome de Jervell-Lange Nielsen/fisiopatologia , Canal de Potássio KCNQ1/genética , Síndrome do QT Longo/patologia , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Criança , Implante Coclear , Diagnóstico Diferencial , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Qualidade de Vida
4.
Cochlear Implants Int ; 19(6): 350-354, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30227792

RESUMO

Congenital long QT syndrome (cLQTS) is an inherited cardiac ion channelopathy characterized by a long corrected-QT interval on the ECG, associated with a risk of syncope and sudden death as a result of arrhythmias. The archetypal arrhythmia associated with cLQTS is torsade de pointes which may degenerate into ventricular fibrillation. Children with Jervell and Lange-Neilsen syndrome have the combination of cLQTS and congenital sensorineural deafness and may present for cochlear implantation (CI). Sympathetic stimulation and administration of QT-prolonging medications may trigger arrhythmias in children with cLQTS and thus the perioperative period is a time of increased risk of adverse events, with deaths reported in the CI literature. Our Paediatric Cochlear Implant Programme had previously elected to discontinue offering CI to children with cLQTS following a perioperative death. However, subsequent demand for this service by parents led us to develop and introduce a multidisciplinary, evidence-based pathway of care. This pathway modifies the perioperative management of these children to reduce the associated risk. We present the cases of four children with cLQTS who underwent CI in our specialist children's hospital.


Assuntos
Implante Coclear/efeitos adversos , Surdez/cirurgia , Síndrome de Jervell-Lange Nielsen/complicações , Síndrome do QT Longo/complicações , Criança , Surdez/congênito , Feminino , Humanos , Síndrome do QT Longo/congênito , Masculino
5.
Auris Nasus Larynx ; 45(4): 890-893, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29588140

RESUMO

Jervell and Lange-Nielsen syndrome (JLNS), a rare autosomal recessive congenital QT prolongation syndrome, is characterized by cardiac arrhythmias, syncopal episodes, and profound deafness. A cochlear implant (CI) for patients with JLNS is expected to result in hearing improvement. Sometimes, defibrillation is required if a patient experiences lethal arrhythmia. In this paper, we report a pediatric patient with JLNS who received defibrillation after CI surgery in his right ear at the age of 2 years. With intensive care, the post-operative course was uneventful, and the patient acquired satisfactory speech and hearing abilities. Five years after the surgery, he underwent defibrillation because of the incidence of syncopal attack. Thereafter, arrhythmic syncope recurred three times, which necessitated defibrillation therapy. To prevent recurrence of cardiac arrhythmia, he underwent ICD (implantable cardioverter-defibrillator) implantation at the age of 11 years. At present, CI works well and provides good hearing, while syncopal attack is prevented by ICD. From the experience of this case, electronic circuit of CI is thought to tolerate emergency countershock if the speech processor is removed.


Assuntos
Implante Coclear , Implantes Cocleares , Cardioversão Elétrica , Síndrome de Jervell-Lange Nielsen/terapia , Síncope/prevenção & controle , Criança , Desfibriladores Implantáveis , Falha de Equipamento , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Masculino , Síncope/etiologia
6.
Heart Rhythm ; 13(11): 2186-2192, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27451284

RESUMO

BACKGROUND: Patients with Jervell and Lange-Nielsen syndrome (JLNS) exhibit severe phenotypes that are characterized by congenital deafness, very long QT intervals, and high risk of life-threatening arrhythmias. Current treatment strategies include high doses of beta-blocker medication, left cardiac sympathetic denervation, and ICD placement, which is challenging in young children. OBJECTIVE: The purpose of this study was to evaluate the safety and effect of pacing in addition to beta-blocker treatment in children with JLNS. METHODS: All genetically confirmed patients with JLNS born since 1999 in Norway were included in the study. Data on history of long QT syndrome-related symptoms, QT interval, and beta-blocker and pacemaker treatment were recorded. RESULTS: A total of 9 patients with QT intervals ranging from 510 to 660 ms were identified. Eight patients developed long QT syndrome-related symptoms, and 1 patient died before diagnosis. The survivors received beta-blocker medication. Seven patients also received a pacemaker; 1 had a ventricular lead and 6 had atrial leads. The patient with the ventricular lead died during follow-up. The 6 patients with atrial leads survived without events at a mean follow-up of 6.9 years after pacemaker implantation. Two patients received prophylactic upgrade to a 2-chamber ICD. CONCLUSION: No arrhythmic events occurred in 6 very young JLNS patients who received atrial pacing in combination with increased doses of beta-blockers during 7-year follow-up. If confirmed in additional patients, this treatment strategy may prevent life-threatening arrhythmias in this high-risk patient group and may act as a bridge to insertion of a 2-chamber ICD when left cardiac sympathetic denervation is not available.


Assuntos
Antagonistas Adrenérgicos beta/administração & dosagem , Arritmias Cardíacas , Estimulação Cardíaca Artificial/métodos , Síndrome de Jervell-Lange Nielsen , Canal de Potássio KCNQ1/genética , Simpatectomia/métodos , Adolescente , Arritmias Cardíacas/genética , Arritmias Cardíacas/prevenção & controle , Criança , Pré-Escolar , Implante Coclear/métodos , Surdez/congênito , Surdez/cirurgia , Desfibriladores Implantáveis , Relação Dose-Resposta a Droga , Eletrocardiografia/métodos , Feminino , Sistema de Condução Cardíaco/efeitos dos fármacos , Sistema de Condução Cardíaco/fisiopatologia , Humanos , Lactente , Síndrome de Jervell-Lange Nielsen/complicações , Síndrome de Jervell-Lange Nielsen/epidemiologia , Síndrome de Jervell-Lange Nielsen/fisiopatologia , Síndrome de Jervell-Lange Nielsen/terapia , Masculino , Mutação , Noruega/epidemiologia , Avaliação de Processos e Resultados em Cuidados de Saúde
7.
Int J Pediatr Otorhinolaryngol ; 79(9): 1544-7, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26205899

RESUMO

OBJECTIVES: To share our experience in cochlear implanted patients with Jervell and Lange-Nielsen syndrome (JLNS), to review the literature results and to disclose precautions which have to be taken dealing with these patients. MATERIALS AND METHODS: Electrocardiograms (ECG) of 503 children with congenital bilateral profound hearing loss which were cochlear implanted in cochlear implant center of a tertiary hospital were evaluated for long QT syndrome. Clinical reports of the patients with JLNS were evaluated and a review of literature performed. RESULTS: The prevalence of disease was 0.79% (four cases) in our center which is in the range of literature reports (0-2.6%). None of our patients had a history of syncopal attack. Two patients (50%) were born from parents with consanguineous marriage. Considering all precautions their cochlear implant surgeries were done uneventfully. A review of the literature has identified sixteen reports on cochlear implantation in a total of 38 children with JLNS. Similar to our cases none of the authors reported cardiac events during device switch-on. Nine available reports about the outcome of cochlear implantation in these patients indicated good auditory outcome. CONCLUSION: It is recommended that all congenitally deaf patients have an ECG taken as a part of the evaluation. As auditory stimuli is reported to be a specific trigger, it is prudent to activate the processor with continuous heart monitoring even though there is no reported cardiac event during device switch-on. Cochlear implantation can be performed relatively safely in these patients if necessary precautions have been taken appropriately and their auditory outcome is good. Triggers of the cardiac events should be avoided throughout their life.


Assuntos
Implante Coclear/efeitos adversos , Implantes Cocleares , Síndrome de Jervell-Lange Nielsen/cirurgia , Criança , Pré-Escolar , Implante Coclear/métodos , Eletrocardiografia , Feminino , Humanos , Lactente , Síndrome de Jervell-Lange Nielsen/complicações , Masculino
8.
Clin Genet ; 86(1): 85-90, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23844633

RESUMO

Long QT syndrome (LQTS), a rare congenital cardiac condition associated with life-threatening ventricular arrhythmias is characterized by a prolonged QT interval on electrocardiograph corrected for heart rate [corrected QT (QTc)]. LQTS has been historically categorized into the autosomal dominant Romano-Ward syndrome (RWS) and the autosomal recessive Jervell and Lange-Nielsen syndrome (JLNS). JLNS is associated with prelingual sensorineural deafness. Both types of LQTS can be caused by mutations in channel genes (e.g. KCNQ1) responsible for potassium homeostasis in cardiac myocytes and cochlea. Autosomal dominant mutations often cause the RWS phenotype and homozygous or compound heterozygous mutations contribute to JLNS. Two First Nations communities in northern British Columbia are affected disproportionately with LQTS largely due to the V205M mutation in KCNQ1, however, the pathology and phenotypic expression for those V205M homozygous has been unknown. Here, we show that four V205M homozygous individuals have a significantly higher 'peak' QTc, and a more severe cardiac phenotype compared with 41 V205M heterozygous carriers and 57 first to third degree relatives without mutations. Given the lack of prelingual deafness the homozygous V205M LQTS patients present with a phenotype more typical of RWS than JLNS.


Assuntos
Surdez/patologia , Síndrome de Jervell-Lange Nielsen/genética , Canal de Potássio KCNQ1/genética , Miocárdio/patologia , Fenótipo , Síndrome de Romano-Ward/genética , Colúmbia Britânica , Surdez/etiologia , Eletrocardiografia , Homozigoto , Humanos , Índios Norte-Americanos , Síndrome de Jervell-Lange Nielsen/complicações , Síndrome de Jervell-Lange Nielsen/patologia , Mutação de Sentido Incorreto/genética , Síndrome de Romano-Ward/patologia
9.
Rev. otorrinolaringol. cir. cabeza cuello ; 73(3): 268-270, dic. 2013. ilus
Artigo em Espanhol | LILACS | ID: lil-704561

RESUMO

El síndrome de Jervell y Lange-Nielsen es una forma poco frecuente de síndrome de QT largo. Su herencia es autosómica recesiva y se manifiesta con sordera neurosensorial. Revisamos el caso de una niña de 7 años implantada coclear bilateral. Tras un episodio sincopal se realiza el diagnóstico de síndrome de QT largo, el estudio genético confirma el diagnóstico. Recomendamos realizar electrocardiograma a todos los niños con hipoacusia severa con el objeto de descartar este síndrome.


The Jervell and Lange-Nielsen (JLNS) is an uncommon form of long QT syndrome. His inheritance is autosomal recessive and manifests as a sensorineural deafness. We review the case of a 7 year old girl bilateral cochlear implanted. After a syncope episode, a long QT syndrome was confirmed by genetic study. We recommend electrocardiogram (ECG) to all children with severe hearing loss in order to rule out this syndrome.


Assuntos
Humanos , Feminino , Criança , Síndrome de Jervell-Lange Nielsen/diagnóstico , Síndrome de Jervell-Lange Nielsen/fisiopatologia , Perda Auditiva/etiologia , Síndrome do QT Longo/diagnóstico , Síndrome do QT Longo/fisiopatologia , Síndrome de Jervell-Lange Nielsen/complicações , Eletrocardiografia , Perda Auditiva/cirurgia , Perda Auditiva/genética
10.
Int J Pediatr Otorhinolaryngol ; 77(8): 1303-7, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23809516

RESUMO

INTRODUCTION: Cochlear implantation is a safe surgery for restoration of hearing in profoundly deaf candidates. Profound deafness may at times, manifest as a part of a syndrome associated with cardiac anomalies. Cardiac co-morbidities may influence cochlear implantation in a spectrum of ways from minor intra operative issues to major life threatening complications. Issues related to pre operative, intra operative and post operative care needs to be addressed by an efficient in house cardiologist. OBJECTIVES: Our retrospective study was aimed at analyzing the various cardiac co-morbidities encountered in 30 out of 500 cochlear implantees over a period of 14 years (July 1999-June 2012). This study was focused on developing a profile of cardiac complications influencing cochlear implantation and suggests a protocol for management of various cardiac issues related to cochlear implantation. Our article also reflects the cardiologist's perspective of peri-operative care to be given during cochlear implantation. Relevant literature has been reviewed. METHODS: Case series of 30 profoundly deaf children (below 12 years) who had associated cardiac problems and underwent cochlear implantation in our institution were included in our study. Overall cardiac disease was identified in 30 out of 500 implantees (16.6%) in our experience. The cardiac disease can be categorized into 3 groups: candidates with isolated Patent Ductus Arteriosus (PDA) as Group A (8/30), candidates with syndrome and other anomalies with PDA association as Group B (18/30), and candidates with syndromes without PDA association as Group C (4/30). RESULTS: The overall incidence of cardiac problems in profoundly deaf candidates is identified. Descriptive profile of the same has been created and appropriate management for the same described. CONCLUSIONS: A protocol for management of cardiac co-morbidities influencing cochlear implantation has been designed and detailed insight for the optimal management of these issues has been discussed with cardiologist's perspective.


Assuntos
Implante Coclear , Surdez/complicações , Surdez/terapia , Permeabilidade do Canal Arterial/complicações , Síndrome de Jervell-Lange Nielsen/complicações , Estenose da Valva Pulmonar/complicações , Criança , Protocolos Clínicos , Implantes Cocleares , Surdez/patologia , Permeabilidade do Canal Arterial/cirurgia , Feminino , Humanos , Hipertensão Pulmonar/complicações , Hipertensão Pulmonar/cirurgia , Síndrome de Jervell-Lange Nielsen/cirurgia , Masculino , Assistência Perioperatória , Estenose da Valva Pulmonar/cirurgia , Estudos Retrospectivos
11.
Cardiol Young ; 23(4): 530-9, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23668803

RESUMO

OBJECTIVE: To report the autosomal dominant inheritance of the Jervell and Lange-Nielsen syndrome in a highly inbred family, the initiation of Torsades de Pointes, and the natural history of the syndrome based on a 16-year follow-up of the kindred. METHOD: A family tree was constructed that included 66 blood relatives from three successive generations. Electrocardiograms were obtained from 59 living members including the proband, four members from a nuclear family, and 54 from the extended family. Evoked response audiometry was recorded for the proband and the nuclear family. All 59 family members were followed up regularly for 16 years. RESULTS: A total of 24 living members were affected--QTc: 480-680 ms. The proband had long QTc, bilateral high-tone sensorineural deafness, recurrent syncope, and Torsades de Pointes. The asymptomatic father had long QTc and unilateral high-tone sensorineural deafness that involved specifically the left ear. One asymptomatic sibling of the proband had long QTc and normal hearing. The mother and another sibling were asymptomatic; QTc and hearing were normal in both. A total of 21 affected members from the extended family had only long QTc, and all were asymptomatic. There were three congenitally deaf first cousins who had recurrent syncope and adrenergic-triggered sudden death. In all, seven of 10 parents had consanguineous marriage to a first cousin. Each affected offspring had at least one affected parent. The severely symptomatic proband who received only ß-blocker therapy and the 23 affected members without antiadrenergic therapy, all remained asymptomatic throughout the 16-year follow-up period. CONCLUSION: Jervell and Lange-Nielsen syndrome was inherited as autosomal dominant in this kindred. The majority of the affected members had a mild phenotype. The severity of auditory and cardiac phenotypes corresponded.


Assuntos
Consanguinidade , Parada Cardíaca/genética , Síndrome de Jervell-Lange Nielsen/genética , Torsades de Pointes/genética , Adolescente , Adulto , Doenças Assintomáticas , Criança , Pré-Escolar , Morte Súbita Cardíaca/etiologia , Progressão da Doença , Eletrocardiografia , Feminino , Seguimentos , Perda Auditiva Neurossensorial/etiologia , Perda Auditiva Neurossensorial/genética , Parada Cardíaca/etiologia , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Síndrome de Jervell-Lange Nielsen/fisiopatologia , Masculino , Pessoa de Meia-Idade , Linhagem , Fenótipo , Síncope/etiologia , Síncope/genética , Síncope/fisiopatologia , Torsades de Pointes/etiologia , Torsades de Pointes/fisiopatologia
13.
J Laryngol Otol ; 122(3): 314-7, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17498328

RESUMO

Jervell, Lange-Nielsen syndrome is a condition that causes profound hearing loss and disruption of the normal cardiac rhythm. This disorder is a form of long QT syndrome, a cardiac disorder that causes the cardiac muscle to take longer than usual to recharge between beats. A retrospective case study was performed to document cochlear implantation in three profoundly deaf children (two of them siblings) with Jervell, Lange-Nielsen syndrome. We discuss diagnosis and management of this syndrome and also the long-term performance of cochlear implantation in these Iranian patients, referring especially to the role of the ENT specialist in diagnosis and treatment. The collected data show that cochlear implantation can be relatively safely performed in patients with Jervell, Lange-Nielsen syndrome and that these children received significant benefit from cochlear implantation.


Assuntos
Implante Coclear/reabilitação , Perda Auditiva Neurossensorial/etiologia , Síndrome de Jervell-Lange Nielsen/complicações , Distúrbios da Fala/terapia , Pré-Escolar , Implante Coclear/métodos , Feminino , Perda Auditiva Neurossensorial/cirurgia , Humanos , Lactente , Síndrome de Jervell-Lange Nielsen/cirurgia , Masculino , Estudos Retrospectivos , Resultado do Tratamento
14.
Arch Mal Coeur Vaiss ; 100(5): 359-64, 2007 May.
Artigo em Francês | MEDLINE | ID: mdl-17646758

RESUMO

UNLABELLED: Data on the Jervell and Lange-Nielsen syndrome (JLN), the long QT syndrome (LQTS) variant associated with deafness and caused by homozygous or compound heterozygous mutations on the KCNQ1 or on the KCNE1 genes encoding the IKs current, are still largely based on case reports. We analyzed data from 186 JLN patients obtained from the literature (31%) and from individual physicians (69%). Most patients (86%) had cardiac events and 50% were symptomatic already by age 3. Their QTc was markedly prolonged (557 +/- 65 ms). Most of the arrhythmic events (95%) were triggered by emotions or exercise. Females are at lower risk for cardiac arrest and sudden death (CA/SD). A QTc>550 ms and history of syncope during the first year of life are independent predictors of subsequent CA/SD. Most mutations (90.5%) are on the KCNQ1 gene; mutations on the KCNE1 gene are associated with a more benign course. beta-blockers have only partial efficacy as 51% of the patients had events despite therapy and 29% had CA/SD. CONCLUSIONS: JLN syndrome is a most severe variant of LQTS, with a very early onset, major QTc prolongation, and is not well responsive to beta-blockers. Subgroups at relatively lower risk for CA/SD are identifiable and include females, patients with a QTc pound550 ms, without events in the first year of life, and with mutations on KCNE1. Early therapy with ICDs has to be considered.


Assuntos
Síndrome de Jervell-Lange Nielsen/complicações , Adolescente , Antagonistas Adrenérgicos beta/uso terapêutico , Adulto , Fatores Etários , Criança , Pré-Escolar , Morte Súbita Cardíaca/etiologia , Eletrocardiografia , Emoções , Exercício Físico/fisiologia , Feminino , Parada Cardíaca/etiologia , Humanos , Lactente , Síndrome de Jervell-Lange Nielsen/tratamento farmacológico , Síndrome de Jervell-Lange Nielsen/genética , Canal de Potássio KCNQ1/genética , Masculino , Mutação/genética , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Estudos Retrospectivos , Fatores Sexuais , Síncope/etiologia
16.
Am J Physiol Cell Physiol ; 292(1): C591-602, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17005601

RESUMO

Cochlear marginal cells and vestibular dark cells transport potassium into the inner ear endolymph, a potassium-rich fluid, the homeostasis of which is essential for hearing and balance. We have formulated an integrated mathematical model of ion transport across these epithelia that incorporates the biophysical properties of the major ion transporters and channels located in the apical and basolateral membranes of the constituent cells. The model is constructed for both open- and short-circuit situations to test the extremes of functional capacity of the epithelium and predicts the steady-state voltages, ion concentrations, and transepithelial currents as a function of various transporter and channel densities. We validate the model by establishing that the cells are capable of vectorial ion transport consistent with several experimental measurements. The model indicates that cochlear marginal cells do not make a significant direct contribution to the endocochlear potential and illustrates how changes to the activity of specific transport proteins lead to reduced K(+) flux across the marginal and dark cell layers. In particular, we investigate the mechanisms of loop diuretic ototoxicity and diseases with hearing loss in which K(+) and Cl(-) transport are compromised, such as Jervell and Lange-Nielsen syndrome and Bartter syndrome, type IV, respectively. Such simulations demonstrate the utility of compartmental modeling in investigating the role of ion homeostasis in inner ear physiology and pathology.


Assuntos
Cóclea/metabolismo , Modelos Biológicos , Potássio/metabolismo , Vestíbulo do Labirinto/metabolismo , Síndrome de Bartter/complicações , Síndrome de Bartter/metabolismo , Transporte Biológico , Fenômenos Biofísicos , Biofísica , Proteínas de Transporte/metabolismo , Cloretos/metabolismo , Cóclea/citologia , Cóclea/fisiologia , Simulação por Computador , Eletrofisiologia , Endolinfa/metabolismo , Perda Auditiva/etiologia , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Síndrome de Jervell-Lange Nielsen/metabolismo , Reprodutibilidade dos Testes , Inibidores de Simportadores de Cloreto de Sódio e Potássio/envenenamento , Estria Vascular/citologia , Estria Vascular/metabolismo , Vestíbulo do Labirinto/citologia
17.
J Med Assoc Thai ; 86(12): 1149-55, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-14971523

RESUMO

OBJECTIVES: To survey the prevalence of the long QT syndrome (LQTS), especially Jervell-Lange-Nielsen syndrome (JLNS), in Thai children (The first such study). BACKGROUND: LQTS is a rare inherited disease with a prevalence of 0.21 per cent in children with congenital deafness from other reports. These patients carry a high risk of recurrent syncope and fatal ventricular arrhythmia. STUDY DESIGN: Cross-sectional survey from January 2000 to August 2000. METHOD: A total of 276 children with congenital sensori-neural hearing loss were included. A questionnaire was employed and all children were examined by a pediatric cardiologist to rule out organic heart disease. EKGs were obtained and QTc intervals were blindly measured using standard methods in L2, V5 or any other leads with the longest QTc interval by three pediatric cardiologists. If QTc interval is prolonged, additional EKG (up to 3) were done to confirm the finding. Schwartz criteria was used to identify index cases with LQTS after repeated EKGs, and exercise stress tests. Also, echocardiography were done in patients suspected of having LQTS. RESULTS: A total of 14 children needed a third EKG and more work ups due to persistent long QTc interval after 2 consecutive EKG studies with QTc intervals ranged from 456 msec to 466 msec, and Schwartz score from 1.5 to 2.5. There were 6 twins and no triplets in the study. Finally, two subjects (not twins or siblings) had persistent prolonged QTc intervals after 3 EKG studies. After the exercise stress test, both still had a prolonged QTc interval, not corrected to the normal QTc interval even at the exercise peak. There was no cardiac abnormality either structurally or functionally from the 2D echocardiogram and Doppler color flow study. CONCLUSION: The possible prevalence of JLNS was 0.7 per cent (2/276). Both children were in the low-risk group for having LQTS.


Assuntos
Perda Auditiva Neurossensorial/congênito , Perda Auditiva Neurossensorial/complicações , Síndrome de Jervell-Lange Nielsen/complicações , Síndrome de Jervell-Lange Nielsen/epidemiologia , Adolescente , Adulto , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Masculino , Prevalência , Tailândia/epidemiologia
18.
Pediatr Ann ; 32(11): 751-6, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22111157

RESUMO

The majority of cases of sudden, unexpected death in athletes are related to cardiovascular anomalies. Some of these anomalies may be diagnosed with a preparticipation examination including a thorough history of previous symptoms that would suggest a cardiovascular diagnosis. In addition, a complete and thorough family history should be obtained, not only from the athlete but also from the athlete's parents. If any family members have the diagnosis of HCM or prolonged Q-T syndrome, a history of sudden, unexpected death, or have used a pacemaker, this should be a possible clue for diagnosis. Once a cardiovascular diagnosis is made, the athlete should be subject to the accepted guidelines for participation in athletics and competitive sports.


Assuntos
Morte Súbita/etiologia , Cardiopatias/complicações , Esportes , Adolescente , Cardiomiopatia Hipertrófica/complicações , Anomalias dos Vasos Coronários/complicações , Morte Súbita Cardíaca/etiologia , Eletrocardiografia , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Síndrome de Marfan/complicações
19.
Int J Pediatr Otorhinolaryngol ; 66(3): 213-21, 2002 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-12443809

RESUMO

A case of familial prolonged QT interval and congenital sensorineural hearing loss is described emphasising the diagnostic and management implications. Jervell and Lange-Nielsen syndrome is important because of its potential association with sudden death in children with congenital sensorineural deafness. It is known to be associated with mutations of the genes KCNQ1 (KVQTI) and KCNE1 (Isk). The underlying molecular abnormality leads to cardiac and cochlear dysfunction through a potassium channel defect. All children with congenital sensorineural hearing loss who have suffered unexplained syncopal attacks or convulsions should be screened for this syndrome. There is also a strong case for including a 12 lead ECG as part of the investigative work up of all children with congenital sensorineural deafness in whom a firm aetiology has not been established.


Assuntos
Implante Coclear/métodos , Predisposição Genética para Doença , Perda Auditiva Neurossensorial/genética , Perda Auditiva Neurossensorial/cirurgia , Síndrome de Jervell-Lange Nielsen/genética , Adolescente , Audiometria , Limiar Auditivo , Criança , Seguimentos , Perda Auditiva Neurossensorial/diagnóstico , Humanos , Síndrome de Jervell-Lange Nielsen/complicações , Masculino , Linhagem , Medição de Risco , Resultado do Tratamento
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