Arsenic Poisoning-Induced Sensorineural Hearing Loss: A Case Report.

Arsenic is frequently used in alternative medicine, and it is critical to promptly identify and treat suspected arsenic toxicity in patients. In a case study, a female patient presented with several symptoms, including nausea, vomiting, bilateral tinnitus, hearing loss, vertigo, and other associated complaints. After admission, the patient showed lethargy, and topical application of Chinese herbal medicine was found on her left breast, along with visible pigmentation on her torso. Examination revealed severe bilateral sensorineural deafness, liver and kidney injury, and pancytopenia. Due to the presence of broken skin, toxicological analysis detected elevated levels of arsenic in both blood (113 ng/mL) and urine (865.4 ng/mL). The patient was diagnosed with arsenic poisoning and received symptomatic treatment, including detoxification. Unfortunately, the patient died due to long-term exposure to arsenic. Therefore, early identification of the etiology is crucial for managing cases of arsenic poisoning.

Pharmacogenetics of aminoglycoside-related ototoxicity: a systematic review.

BACKGROUND: Aminoglycosides (AGs) are important antibiotics in the treatment of Gram-negative sepsis. However, they are associated with the risk of irreversible sensorineural hearing loss (SNHL). Several genetic variants have been implicated in the development of ototoxicity. OBJECTIVES: To evaluate the pharmacogenetic determinants of AG-related ototoxicity. METHODS: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses and was registered on Prospero (CRD42022337769). In Dec 2022, PubMed, Cochrane Library, Embase and MEDLINE were searched. Included studies were those reporting original data on the effect of the AG-exposed patient's genome on the development of ototoxicity. RESULTS: Of 10 202 studies, 31 met the inclusion criteria. Twenty-nine studies focused on the mitochondrial genome, while two studied the nuclear genome. One study of neonates found that 30% of those with the m.1555A > G variant failed hearing screening after AG exposure (level 2 evidence). Seventeen additional studies found the m.1555A > G variant was associated with high penetrance (up to 100%) of SNHL after AG exposure (level 3-4 evidence). Nine studies of m.1494C > T found the penetrance of AG-related SNHL to be up to 40%; however, this variant was also identified in those with SNHL without AG exposure (level 3-4 evidence). The variants m.1005T > C and m.1095T > C may be associated with AG-related SNHL; however, further studies are needed. CONCLUSIONS: This review found that the m.1555A > G and m.1494C > T variants in the MT-RNR1 gene have the strongest evidence in the development of AG-related SNHL, although study quality was limited (level 2-4). These variants were associated with high penetrance of a SNHL phenotype following AG exposure.

Comparison of side effects of different steroids used in intratympanic injections.

OBJECTIVES: This study aimed to compare the side effects of different steroids used in the intratympanic injections (IT). METHODS: One hundred and sixty patients diagnosed with sudden sensorineural hearing loss and undergoing IT were assigned to four groups based on the type or concentration of steroids administered (Group DM5: 5 mg/ml Dexamethasone sodium phosphate; Group DM10: 10 mg/ml Dexamethasone sodium phosphate; Group MP: 40 mg/ml Methylprednisolone sodium succinate; Group BM: 4 mg/ml Betamethasone sodium phosphate). Each group comprised 40 patients, and all participants received IT six times. The study assessed and compared the degrees and duration of pain, dizziness, and tympanic membrane damage following IT. Patients were asked to report the pain they felt using the numeric rating scale (NRS). RESULTS: NRS scores for pain after IT showed significant differences among the four groups (p < 0.001). The average NRS scores for pain in each group were as follows: Group DM5: 1.53 ± 1.04; Group DM10: 1.45 ± 1.30; Group MP: 4.33 ± 2.22; Group BM: 6.03 ± 1.46. The durations of pain after IT also exhibited significant differences among the four groups (p < 0.001), with the longest duration observed in Group MP at 31.93 ± 15.20 min. CONCLUSION: Different types of steroids could lead to varying degrees of pain when used in IT. Betamethasone could cause the most severe pain, and methylprednisolone could result in the longest duration of pain.

Audiologic and vestibular assessment in children and adolescents with transfusion dependent beta thalassemia major: The era of deferasirox film coated tablet.

BACKGROUND: Hearing impairment has frequently been described in ß-thalassemia patients with a significant impact on the patients' quality of life. Most studies provided evidence of deferoxamine (DFO) dose-related ototoxicity, however, the data is scarce regarding deferasirox (DFX) as a sole iron chelator. AIM: We aimed to assess the prevalence and risk factors of sensorineural hearing loss (SNHL) and vestibular dysfunction in regularly transfused ß-thalassemia patients who had been treated with DFX film coated tablets. METHODS: We conducted a case control study on 57 transfusion dependent ß-thalassemia patients with a mean age of 15.3 years who received DFX FCT as monotherapy for at least one consecutive year, and 57 healthy age and sex-matching controls. Comprehensive audiological evaluations using pure tone audiometry (PTA) and transient evoked otoacoustic emission (TEOAE) as well as vestibular evaluation using Video-nystagmography (VNG) were done. RESULTS: SNHL was identified in 12 patients (21.1 %) using PTA and a statistically significant difference was detected between controls and patients at 6 KHz and 12 KHz frequencies. A higher incidence of SNHL was detected using TEOAE, 22 patients (43.1 %) failed to pass TEOAE, with a statistically significant decrease in the signal at frequencies 1, 4 KHz bilaterally and at frequencies 1.5, 2 KHz in the right ear compared to controls. Canal paresis was detected in 21 (36.8 %) of thalassemic children using bithermal caloric test with significantly more unilateral weakness than control children (P = 0.008). We found no significant correlation between audio-vestibular dysfunction and age, sex, serum ferritin, frequency of blood transfusion and dose of DFX FCT in thalassemic children. CONCLUSION: We conclude that the incidence of SNHL and vestibular dysfunction was high among transfusion dependent ß-thalassemia patients. Therefore, we recommend performing pre-treatment baseline audio-vestibular assessment and yearly audio-vestibular monitoring to early detect high risk patients and initiate timely management to prevent permanent damage.

Hearing results with combination steroid therapy for sudden sensorineural hearing loss.

BACKGROUND: Sudden Sensorineural Hearing Loss was described by Mc. Cabe in 1979 and, since then, many authors have tried to define, explain and correctly treat this disease. The National Institute on Deafness and Other Communication Disorders defines it as sudden sensorineural hearing loss of at least 30 dB in three contiguous audiometric frequencies in a period of 72 hours. Among the therapeutic strategies, corticosteroids have been shown to have the greatest benefit due to their anti-inflammatory and anti-cellular stress effects. OBJECTIVE: To determine the hearing results with combined steroid therapy in patients with sudden sensorineural hearing loss (SSHL), according to the Siegel recovery criteria scale. METHOD: Study carried out in the otorhinolaryngology and head and neck surgery service of the Centro Médico Naval, Ciudad de México, where 150 patients diagnosed with SSHL and who received combined therapy with intratympanic dexamethasone and systemic prednisone were included. RESULTS: Therapeutic effectiveness was demonstrated by correlating therapeutic success in 82% of cases and therapeutic failure in 18% of cases, by correlating it with the Siegel recovery criteria scale. When evaluating the general average of the pure tone average levels at the beginning and 6 weeks after treatment, a statistically significant difference was obtained (p = 0.001). The average of the speech audiometry at the beginning and 6 weeks later had a statistically significant difference (p = 0.001). CONCLUSIONS: Initial combined steroid treatment for SSHL has been shown to have beneficial results according to Siegel recovery criteria scale.

ANTECENDENTES: La Hipoacusia Neurosensorial Súbita Idiopática fue descrita por Mc. Cabe en 1979 y, desde entonces, muchos autores han tratado de definir, explicar y tratar correctamente esta enfermedad. El Nacional Institute on Deafness and Other Communication Disorders la define como pérdida auditiva neurosensorial brusca de al menos 30 dB en tres frecuencias audiométricas contiguas en un periodo de 72 horas. Entre las estrategias terapéuticas, los corticosteroides han demostrado tener mayor beneficio por sus efectos antiinflamatorios y antiestrés celular. OBJETIVO: Determinar los resultados auditivos con la terapia de esteroides combinados en pacientes con hipoacusia neurosensorial súbita idiopática (HNSI), de acuerdo a la escala de criterios de recuperación de Siegel. MÉTODO: Estudio realizado en el servicio de otorrinolaringología y cirugía de cabeza y cuello del Centro Médico Naval, en Ciudad de México, en el que se incluyeron 150 pacientes con diagnóstico de HNSI y que recibieron terapia combinada con dexametasona intratimpánica y prednisona sistémica. RESULTADOS: Se demostró una efectividad terapéutica al correlacionar el éxito terapéutico en el 82% de los casos y un fracaso terapéutico en el 18% de los casos según la escala de criterios de recuperación de Siegel. Al evaluar el promedio general de los niveles de promedio de tonos puros al inicio y 6 semanas posterior al tratamiento se obtuvo una diferencia estadísticamente significativa (p = 0.001). El promedio de las logoaudiometrías al inicio y 6 semanas posterior al tratamiento tuvo una diferencia estadísticamente significativa (p = 0.001). CONCLUSIONES: El tratamiento combinado con esteroides de manera inicial para la HNSI ha demostrado tener resultados benéficos de acuerdo con la escala de criterios de recuperación de Siegel.

Audiological follow-up in transplant patients treated with calcineurin immunosuppressants "Calcineurin inhibitors and Ototoxicity" / Seguimiento audiológico en pacientes trasplantados en tratamiento con inmunosupresores inhibidores de calcineurina

BACKGROUND: Ototoxicity is a side effect of drugs and medications that usually leads to bilateral and symmetric sensorineural hearing loss that commonly affects the high-frequency range initially, with or preceded by tinnitus. Possible ototoxic side effects of calcineurin inhibitor immunosuppressants have been suggested, but this remains unclear. Therefore, this study aims to evaluate audiological changes in patients undergoing transplantation receiving immunosuppressive treatment with calcineurin inhibitors. METHODS: Prospective cohort study. Adult patients undergoing liver or kidney transplantation treated with calcineurin inhibitors were included. Pure-tone audiometry, distortion product otoacoustic emissions, and the Tinnitus Handicap Inventory questionnaire were completed at baseline, one, three, and six months after transplantation. Hearing thresholds were compared and correlated with plasma concentrations of calcineurin inhibitors. RESULTS: Seventeen patients were included, 59% males, with a median age of 54.7 years (29-68 years). Twelve patients underwent liver transplantation, four underwent kidney transplantation, and one patient underwent both. The medianfollow-up was 5.8 months (4-8 months). Significant pure-tone average shifts were observed in two patients. Both cases presented fluctuations in their hearing levels, which were not bilateral or symmetrical and affected the higher frequencies. All patients received tacrolimus within the therapeutic range during the follow-up period. Three different patients exceeded the expected range once; however, they were rapidly corrected and did not correlate with any changes in hearing. CONCLUSIONS: It appears that tacrolimus does not cause hearing loss when levels are within the therapeutic range for a follow-up period of six months post-transplantation.

INTRODUCCIÓN: La ototoxicidad corresponde a un efecto secundario a agentes terapéuticos que se manifiesta como hipoacusia sensorioneural bilateral simétrica de frecuencias agudas. Se postulan posibles efectos ototóxicos de los inmunosupresores inhibidores de la calcineurina, pero hasta la fecha es aún incierto. El objetivo de este estudio fue evaluar los cambios audiológicos en pacientes trasplantados en tratamiento inmunosupresor con inhibidores de calcineurina. MATERIAL Y MÉTODO: Cohorte prospectiva. Se incluyeron pacientes adultos sometidos a trasplante hepático o renal tratados con inhibidores de calcineurina. Se realizó una evaluación otorrinolaringo-lógica pre-trasplante con audiometría tonal, emisiones otoacústicas por producto de distorsión y cuestionario Tinnitus Handicap Inventory. Se realizó una evaluación audiológica de seguimiento uno, tres y seis meses después del trasplante. Se compararon los umbrales auditivos antes y después del inicio del tratamiento inmunosupresor y se correlacionaron con las concentraciones plasmáticas de IC. RESULTADOS: Se incluyeron 17 pacientes, 59% hombres, con una mediana de edad de 54,7 años. La mediana de seguimiento fue 5,8 meses. Se observaron cambios en el promedio tonal puro en dos pacientes, los cuales no seguían un patrón audiométrico sugerente de ototoxicidad. Todos los pacientes recibieron Tacrolimus dentro del rango terapéutico durante el seguimiento. Tres pacientes diferentes excedieron el rango esperado una vez sin embargo, se corrigieron rápidamente y no se correlacionaron con cambios auditivos, puntaje de tinnitus o emisiones otoacústicas. DISCUSIÓN: Impresiona que Tacrolimus no se asocia a hipoacusia cuando los niveles están en rango terapéutico durante un período de seguimiento de seis meses post trasplante.

Audiological follow-up in transplant patients treated with calcineurin immunosuppressants "Calcineurin inhibitors and Ototoxicity".

BACKGROUND: Ototoxicity is a side effect of drugs and medications that usually leads to bilateral and symmetric sensorineural hearing loss that commonly affects the high-frequency range initially, with or preceded by tinnitus. Possible ototoxic side effects of calcineurin inhibitor immunosuppressants have been suggested, but this remains unclear. Therefore, this study aims to evaluate audiological changes in patients undergoing transplantation receiving immunosuppressive treatment with calcineurin inhibitors. METHODS: Prospective cohort study. Adult patients undergoing liver or kidney transplantation treated with calcineurin inhibitors were included. Pure-tone audiometry, distortion product otoacoustic emissions, and the Tinnitus Handicap Inventory questionnaire were completed at baseline, one, three, and six months after transplantation. Hearing thresholds were compared and correlated with plasma concentrations of calcineurin inhibitors. RESULTS: Seventeen patients were included, 59% males, with a median age of 54.7 years (29-68 years). Twelve patients underwent liver transplantation, four underwent kidney transplantation, and one patient underwent both. The medianfollow-up was 5.8 months (4-8 months). Significant pure-tone average shifts were observed in two patients. Both cases presented fluctuations in their hearing levels, which were not bilateral or symmetrical and affected the higher frequencies. All patients received tacrolimus within the therapeutic range during the follow-up period. Three different patients exceeded the expected range once; however, they were rapidly corrected and did not correlate with any changes in hearing. CONCLUSIONS: It appears that tacrolimus does not cause hearing loss when levels are within the therapeutic range for a follow-up period of six months post-transplantation.

Intoxicación por monóxido de carbono: una causa rara de hipoacusia neurosensorial reversible / Reversible sensorineural hearing loss following carbon monoxide poisoning

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The Effects of Riluzole on Cisplatin-induced Ototoxicity

Abstract Introduction Riluzole (2-amino-6-trifluoromethoxy benzothiazole) is known as a neuroprotective, antioxidant, antiapoptotic agent. It may have beneficial effects on neuronal cell death due to cisplatin-induced ototoxicity. Objective To evaluate the effect of riluzole on cisplatin-induced ototoxicity in guinea pigs. Methods Twenty-four guinea pigs, studied in three groups, underwent auditory brainstem response evaluation using click and 8 kHz tone burst stimuli. Subsequently, 5 mg/kg of cisplatin were administered to all animals for 3 days intraperitoneally (i.p.) to induce ototoxicity. Half an hour prior to cisplatin, groups 1, 2 and 3 received 2 ml of saline i.p., 6 mg/kg of riluzole hydrochloride i.p., and 8 mg/kg of riluzole hydrochloride i.p., respectively, for 3 days. The auditory brainstem responses were repeated 24 hours after the last drug administration. The cochleae were analyzed by transmission electron microscopy (TEM). Results After drug administiration, for 8,000 Hz stimulus, group 1 had significantly higher threshold shifts when compared with groups 2 (p < 0.05) and 3 (p < 0.05), and there was no significant difference in threshold shifts between groups 2 and 3 (p > 0.05). Transmission electron microscopy findings demonstrated the protective effect of riluzole on the hair cells and the stria vascularis, especially in the group treated with 8 mg/kg of riluzole hydrochloride. Conclusion We can say that riluzolemay have a protective effect on cisplatin- induced ototoxicity. However, additional studies are needed to confirm these results and the mechanisms of action of riluzole.

Mutação mitocondrial C1494T, deficiência auditiva e uso de antibióticos aminoglicosídeos / C1494T mitochondrial dna mutation, hearing loss, and aminoglycosides antibiotics

Tendo em vista a complexidade do mecanismo da audição, não é difícil compreender que a deficiência auditiva possa resultar de ampla variedade de anomalias geneticamente determinadas, bem como de diversos fatores ambientais. Mutações específicas no gene 12S rRNA em DNA mitocondrial são responsáveis por perda da audição não-sindrômica de herança materna, e pelo aumento da susceptibilidade ototóxica dos antibióticos aminoglicosídeos. Objetivo: Neste trabalho, nós avaliamos a presença da mutação C1494T entre os indivíduos ouvintes e com deficiência auditiva que utilizaram aminoglicosídeos e os que não tiveram contato com o antibiótico. Material e método: Foram estudados 20 pacientes com deficiência auditiva neurossensorial não-sindrômica sem histórico de sensibilização aos aminoglicosídeos e 40 recém-nascidos, prematuros e de alto-risco que utilizaram a droga ototóxica, dos quais 20 eram ouvintes e 20 com perda auditiva. As amostras foram analisadas por PCR-RFLP com a enzima de restrição Hph I. Forma de estudo: Experimental. Resultados: A mutação mitocondrial C1494T no gene 12S rRNA não foi detectada em nenhuma das amostras analisadas. Conclusão: Nossos dados sugerem que a deficiência auditiva dos indivíduos analisados não está relacionada com a ototoxicidade da mutação C1494T, demonstrando que esta mutação não é frequente em nossa população.

In view of the complex mechanism of hearing, it is not difficult to understand that hearing impairment may result from a wide variety of genetically determined anomalies and various environmental factors. Specific mutations in the mitochondrial DNA 12S rRNA gene are responsible for maternally inherited non-syndromic hearing loss, and for increased susceptibility to the ototoxicity of aminoglycoside antibiotics. AIM: To asses the presence of C1494T mutation among individuals with normal hearing and hearing impairment who used aminoglycosides and those who had not had contact with the antibiotic. Material and method: The study was composed of 20 patients with nonsyndromic sensorineural hearing loss without prior use of aminoglycosides and 40 premature and high-risk newborns who used ototoxic drugs, of whom 20 had good hearing and 20 had hearing loss. The samples were analyzed by PCR-RFLP with the restriction enzyme Hph I. Study design: Experimental. Results: The mitochondrial 12S rRNA C1494T mutation was not detected in any of the samples analyzed. Conclusion: Our data suggest that the hearing loss of the individuals we analyzed was not related to the ototoxicity of mutation C1494T, showing that this mutation is not frequent in our population.

Estudo da ototoxicidade em trabalhadores expostos a organofosforados / Ototoxicity study in workers exposed to organophosphate

A exposição ocupacional e ambiental aos agrotóxicos evidencia-se como um grave problema de Saúde Pública em nosso país. Entre os sintomas apresentados, a tonteira se destaca, em decorrência de uma provável ação tóxica. OBJETIVO: O objetivo do estudo é caracterizar os resultados do exame vestibular de trabalhadores rurais expostos ocupacionalmente e ambientalmente aos agrotóxicos organofosforados. MATERIAL E MÉTODO: Foi realizado um estudo de coorte com corte transversal em 18 trabalhadores rurais de Teresópolis, RJ. A faixa etária variou de 16 a 59 anos com uma média de 39,6 anos, sendo 5 trabalhadores do sexo masculino e 13 do sexo feminino. Foram utilizados três questionários com perguntas relacionadas à saúde geral e auditiva e perguntas específicas à tonteira e suas relações com o trabalho. Todos os trabalhadores passaram por uma avaliação clínica e realizaram os exames vectoeletronistagmografia e audiometria. RESULTADOS: Os resultados mostraram que 16 trabalhadores apresentaram alterações do equilíbrio corporal de tipo periférico irritativo e 7 trabalhadores apresentaram perdas auditivas do tipo neurossensorial, sugerindo que os agrotóxicos induzem alterações do sistema vestibular através de uma intoxicação lenta e silenciosa. CONCLUSÕES: O olhar clínico sobre esta população exposta a substâncias neuro-ototóxicas requer uma abordagem interdisciplinar, assegurando uma intervenção terapêutica e preventiva eficaz.

Occupational and environmental exposure to agricultural pesticides represent an important health care problem in our country. Among the symptoms presented, dizziness stands out, because of a probable toxic action. AIM: The goal of our study was to characterize vestibular test results from rural workers occupationally and environmentally exposed to organophosphates used in agricultural pesticides. MATERIALS AND METHODS: We carried out a cohort cross-sectional study with 18 rural workers from Teresópolis, RJ. Age ranged between 16 and 59 years, with a mean value of 39.6 years, 5 were males and 13 females. We used three questionnaires with questions associated with general and auditory health, and more specific questions about dizziness and its association with work. All workers underwent clinical evaluation, audiometry and vectoelectronystagmography. RESULTS: results showed that 16 workers had irritative peripheral body balance disorder and 7 workers had sensorineural hearing loss, thus suggesting that agricultural pesticides cause vestibular alterations through a slow and silent intoxication. CONCLUSIONS: medical care for this population exposed to neurotoxic substances require an interdisciplinary approach, to guarantee efficient preventive and therapeutic measures.

Rastreamento da mutação mitocondrial A1555G em pacientes com deficiência auditiva sensorioneural / Screening of the mitochondrial A1555G mutation in patients with sensorineural hearing loss

A mutação mitocondrial A1555G é a principal alteração associada à surdez ocasionada pelo uso de aminoglicosídeos. OBJETIVO: Investigar a prevalência da mutação A1555G em pacientes com deficiência auditiva sensorioneural com e sem uso de antibióticos aminoglicosídeos. MATERIAL E MÉTODO: Estudo em amostras de 27 pacientes com surdez, como casos, e em 100 neonatos, com audição normal, como grupo controle. O DNA foi extraído de leucócitos de amostras de sangue e "primers" específicos foram utilizados para amplificar o gene do citocromo b e a região que abrange a mutação A1555G do DNA mitocondrial, usando as técnicas da Reação em Cadeia da Polimerase e do Polimorfismo no Comprimento de Fragmentos de Restrição. DESENHO CIENTÍFICO: Estudo de casos em corte transversal. RESULTADOS: A região do gene do citocromo b foi amplificada, sendo confirmada a presença do DNA mitocondrial em todas as 127 amostras do estudo. A mutação A1555G não foi identificada nos 27 pacientes com deficiência auditiva e no grupo controle (100 neonatos). CONCLUSÕES: Os resultados são concordantes com estudos que relatam que a mutação A1555G não é prevalente nas Américas. Há interesse na determinação da real prevalência dessa mutação e na investigação de outras mutações que possam ocasionar deficiência auditiva associada ou não ao uso de aminoglicosídeos na população brasileira.

The A1555G mitochondrial mutation is the main alteration associated with aminoglycoside-induced deafness. AIM: to investigate the prevalence of the A1555G mutation in patients sensorineural hearing loss patients with and without aminoglycosides antibiotic use. MATERIAL AND METHOD: a study of 27 cases with deafness as the sample, and 100 neonates with normal hearing as the control group. DNA was extracted from blood leukocyte samples, and specific oligonucleotide primers were designed to amplify the cytochrome b gene and the region which encloses the A1555G mutation of the mitocondrial DNA using the polymerase chain reaction and restriction fragment length polymorphism. DESIGN: a cross-sectional case study. RESULTS: a region of the cytochrome b gene was amplified and the presence of the mtDNA was confirmed in all of the 127 cases. The A1555G mutation was not found in any of the 27 patients with hearing loss or the control group with 100 neonates. CONCLUSION: the results agree with studies stating that the A1555G mutation is not prevalent in the Americas. There is interest in establishing the real prevalence of this mutation and to investigate other mutations that may cause hearing loss, associated or not with the use of aminoglycosides, in the Brazilian population.

Monitorización de la ototoxicidad por fármacos con productos de distorsión / Monitoring drug ototoxicity With distorsion products

El registro de Productos de Distorsión Acústica es considerado en la actualidad un método audiológico objetivo para evaluar de forma rápida el estado funcional de la cóclea, teniendo interés su uso en la monitorización de la otoxicidad medicamentosa. En este trabajo hemos estudiado una muestra de 40 oídos de pacientes que tomaron un antibiótico aminoglucósido, la tobramicina, realizando dos controles secuenciales con Productos de Distorsión 2fl-f2, deforma previa y posterior a la toma del fármaco, observando disminuciones significativas en las amplitudes de los DP-Gramas en los registros obtenidos. Al mismo tiempo hemos evaluado la influencia que sobre su registro pueda tener la presencia de una hipoacusia neurosensorial previa a la toma de fármaco al dividir a los pacientes en dos grupos: normooyentes y con hipoacusia neurosensorial. Simultáneamente hemos valorado estos pacientes con audiometría tonal, comparando los resultados de las dos técnicas empleadas. Como conclusión, hemos observado la escasa repercusión que el fármaco ha ejercido sobre los umbrales audiométricos, siendo patentes los cambios en el registro de los Productos de Distorsión (AU)

Distortion products are currently considered an objective method for rapidly evaluating the functional status of the cochlea, which is interesting for the monitoring of drug ototoxicity. We studied 40 ears from patients who had received an ototoxic drug, tobramycin. Two consecutive measurements were made using distortion products 2f1-f2, before and after taking the ototoxic agent. A significant reduction was observed in the amplitudes of the DP-grams. At the same time, we evaluated the influence of previous hearing loss on the DP-grams and divided the patients into two groups: normal hearing and sensorineural hearing loss. Patients were evaluated at the same time by conventional audiometry to compare the effect of tobramycin on both tests. To conclude, tobramycin had little effect on audiometric thresholds, but produced an evident change in the amplitude of the distortion products (AU)

Hipoacusia neurosensorial reversible por intoxicación con monóxido de carbono / Reversible neurosensorial hearing loss of intoxication with carbon monoxide

Se presenta el caso de una paciente de 35 años que sufrió una intoxicación crónica por monóxido de carbono (CO), con una sobreexposición final de tipo agudo, por lo cual requirió un tratamiento médico de urgencia y que desarrolló un compromiso otológico bilateral fundamentalmente neurosensorial, de tipo reversible y con compromiso principalmente de los tonos agudos. La intoxicación por CO, es una patología que rara vez se relaciona con alteraciones a nivel del oído. Las intoxicaciones agudas, que son las más frecuentemente diagnosticadas debido a lo evidente y dramático de su sintomatología, no presentan daño coclear presuntamente por el corto tiempo de exposición al CO. Distinto es el caso de la intoxicación de tipo crónica, en la cual la sintomatología es tan inespecífica y solapada que no se sospecha su presencia, unido a las características del gas el cual es inodoro, incoloro e insípido y no irritativo, por lo que ingresa en grandes cantidades al organismo por las vías respiratorias sin que la persona se percate de ello. Por este motivo generalmente es subdiagnosticada. Los estudios realizados en ratas, cobayos y las experiencias de intoxicaciones en humanos han demostrado que produce alteraciones cocleares reversibles

Regeneraçäo de Células após Ototoxicidade com Aminoglicosídeo na Cóclea de Aves / Hair Cell Regeneration in the Avian Cochlea after Ototoxicity with Aminoglycoside

Introduçäo: As células ciliadas podem ser lesada por inúmeros agentes, incluindo os antibióticos aminoglicosídeos. Na cóclea das aves, a perda das células ciliadas pode ser reposta por regeneraçäo. Objetivos: Os objetivos da pesquisa foram estudar o processo de regeneraçäo em aves e a progressäo temporal das lesöes provocadas pela gentamicina. Material e método: No estudo, foi administrada gentamicina em dose única subcutânea de 125 e 250 mg/kg respectivamente, em um e outro grupos de pintos de três dias. As cócleas foram processadas, para anáIise em microscopia eletrônica de varredura, no 1§, 3§, 5§ e 20§ dias após a injeçäo. A sequência celular de degeneraçäo e regeneraçäo foi estudada. No 20§ dia, a maior parte da área cóclear lesada havia sido reposta por células ciliadas e de suporte regeneradas. Estereocílios e microvilos foram observados na superfície apical das células ciliadas regeneradas

Ototoxicidade após o uso tópico de neomicina em pacientes com queimaduras / Ototoxicity after the topic use of neomycin in burned patients

Os utores relatam quatro casos de queimaduras extensas que, após utilizaçäo de creme de neomicina nas áreas cruentas, apresentaram ototoxicidade com graus variáveis de perda auditiva. Discutem o diagnóstico diferencial e alertam para o perigo da absorçäo de medicamentos usados por via tópica