Variations in cochlear size of cochlear implant candidates

Introduction: The cochlear anatomy varies in each individual, and that has an impact on decisions regarding the insertion of electrodes. The measurement of the cochlear size is the routine examination required to choose the proper cochlear implant (CI) electrodes. Objective: To acquire normative data on the size of the cochlea (length, width, height, scala timpani [ST] height, cochlear duct length [CDL]) of CI candidates in Medan, Indonesia. Methods: This descriptive study was conducted based on high-resolution computed tomography (HRCT) temporal bone data and on HRCT temporal data manipulated to reconstruct three-dimensional (3D) multiplanar images with OsiriX MD DICOM Viewer version 9.5.1 (Pixmeo SARL, Bernex, Geneva, Switzerland) viewer of 18 patients (36 ears) who were CI candidates in Medan, Indonesia, in order to determine cochlear length (A), cochlear width, cochlear height, ST height and CDL, calculated through a simple mathematical function. Results: The average cochlear length (A) was 8.75 mm (standard deviation [SD] = 0.31 mm); the average cochlear width was 6.53 mm (SD = 0.35 mm); the average cochlear height was 3.26 mm (SD = 0.24 mm) and the average ST height at the basal cochlea was 1.00 mm (SD = 0.1mm); and 0.71 mm (SD = 0.1 mm) at the half turn of cochlea. The average total CDL was 32.45 mm (SD = 1.31 mm; range: 30.01-34.83 mm). Conclusion: The cochlear size varies in each individual; therefore, the temporal bone measurement of CI candidates using HRCT is essential: for the selection of suitable implant electrodes; to minimize cochlear damages at the insertion of the electrode arrays; and to maximize the hearing improvements (AU)

Caracterização audiológica de crianças em tratamento oncológico / Audiological characterization of children under oncologic treatment

Objetivo Investigar os efeitos do tratamento oncológico no sistema auditivo de crianças. Métodos A amostra foi constituída por 12 crianças de 2 a 12 anos de idade, com diagnóstico de câncer e indicação para radioterapia associada ou não à quimioterapia. Foram realizadas pesquisas das emissões otoacústicas produto de distorção (EOA-PD) e emissões otoacústicas transientes (EOA-TE), antes e após seis meses de tratamento. Resultados Das 24 orelhas, apenas duas (8,3%) falharam para as EOA-TE e EOA-PD e não foi observada alteração significativa após o tratamento oncológico. Conclusão O tratamento oncológico, durante um período de seis meses, não ocasionou alterações auditivas nesta amostra. .

Purpose To investigate the effects of cancer treatment on the auditory system of children. Methods The study population comprised 12 children, aged 2 to 12 years, who had been diagnosed with cancer and recommended radiotherapy with/without chemotherapy. Distortion product otoacoustic emissions (DP-OAE) and transient evoked otoacoustic emissions OAE (TE-OAE) were measured before treatment and after six months of treatment. Results Out of the 24 ears, only two ears (8.3%) failed the TE-OAE and DP-OAE tests, and no significant change was observed after cancer treatment. Conclusion Cancer treatment over a period of six months did not cause hearing impairment in this group of patients. .

Mass and Stiffness Impact on the Middle Ear and the Cochlear Partition

Mass and stiffness affect on the peculiar characteristics of transmission of the middle ear and the distinctive behavior of the cochlear mechanics. Applying the principle of the mass and stiffness, the band-pass characteristic transfer function of the middle ear has been explained. The greatest transfer function of the middle ear, approximately 24-29 dB, is observed at 1-2 kHz in both cat and human species. However, at lower frequencies, the transfer function was disturbed by the stiffness of the middle ear primarily due to middle ear cavity. At higher frequencies, the transfer function was disturbed by the stiffness of the middle ear primarily due to middle ear bones. Several examples, such as an acoustic reflex, otitis media, and otosclerosis are discussed. For understanding the traveling wave of the basilar membrane, different place tuning at certain stimulus frequencies, contrastingly shaped basilar membrane to the cochlear duct, and the structural and physical characteristics of the whole cochlear partition were reviewed in terms of changing width, mass, and stiffness from the base to apex. Being about ten times wider, more massive, and one hundredfold stiffer at the base than the apex, the nature of the cochlear partition to absorb high-frequency energy changes in fluid pressure declines toward the apex. Consequently, at the base of the cochlea, high frequencies stimuli are decoded while low frequencies stimuli are decoded at the apex of the cochlea. Due to these characteristics of the cochlear partition, the direction of the traveling wave was also proved to be in the fashion of base-to-apex always.

Desórdenes en el espectro de la neuropatía auditiva (DENA) / Auditory neuropathy spectrum disorder (ANSD)

Desórdenes en el espectro de la neuropatía auditiva (DENA) es el término más aceptado en la actualidad para definir la antes llamada neuropatía auditiva o desincronía auditiva. Su prevalencia es difícil de estimar debido a sus múltiples etiologías (hiperbilirrubinemia, enfermedades infecciosas, neuropatías sensoriomotoras, hereditarias y/o isquémico-hipóxicas). Clínicamente se manifiesta con alteraciones auditivas y comunicativas variables, desde una discapacidad leve o sin ella, hasta la sordera funcional profunda, que puede ser fluctuante o permanente. En los métodos diagnósticos no se evidencian los potenciales auditivos del tallo cerebral o se notan marcadamente anormales, y hay presencia de emisiones otoacústicas o de microfónicos cocleares. Para el tratamiento inicial de los desórdenes en el espectro de la neuropatía auditiva se sugiere hacer amplificación con audífonos en los casos leves, reservando el implante coclear para los estados más severos. El objetivo del artículo es hacer una revisión de la literatura acerca de los desórdenes en el espectro de la neuropatía auditiva.

Auditory Neuropathy Spectrum Disorders (ANSD) is the most currently accepted term to define the previously called auditory neuropathy or auditory dyssynchrony. Its prevalence is difficult to estimate due to multiple etiologies (hyperbilirubinemia, infectious diseases and sensory-motor, hereditary and/or ischemic-hypoxic neuropathies). Some individuals with AN have little or no communication difficulties while others are functionally deaf. Within the diagnostic criteria abnormal auditory nerve response in ABR are observed absent or markedly abnormal while otoacoustic emissions (OAEs) or the cochlear microphonic (CM) remain present and normal. Within the management of DENA is suggested that some children with ANSD appear to benefit from amplification and auditory based intervention while others require CI or other implants for the most severe cases. The objective of this article is to review the literature on disorders of the auditory neuropathy spectrum.

Recent Advances in Research of Cochlear Tonotopicity / 대한이비인후과학회지

The ability of to discern distinct sound frequencies is attributed to frequency specificity in various locations in the auditory pathway. The cochlear duct is tonotopically organized along its longitudinal axis so that the basal turn responds to high frequency and the apical turn to low frequency sounds. Since the cochlear duct is comprised of heterogeneous components including sensory hair cells, neurons and other cellular and acellular components, integration of their diverse features is essential for establishment of tonotopicity. Recent studies aim to investigate the molecular mechanisms responsible for the cochlear tonotopicity.

Complicaciones y causas de fallo en cirugía de implante coclear en pacientes del servicio de otorrinolaringología del Hospital Universitario Clínica San Rafael / Complications and causes of failure in cochlear implant surgery patients in the “Hospital Universitario Clínica San Rafael” service

Este estudio corresponde a un análisis descriptivo de los pacientes del Hospital Universitario Clínica San Rafael llevados a cirugía de implante coclear entre enero/2000 a diciembre/2010 y describe la ocurrencia de complicaciones menores y mayores en la cirugía de implante coclear con un mínimo de seguimiento de 12 meses. Las complicaciones de la cirugía de implante coclear se dividen en dos categorías; complicaciones menores y mayores. Las complicaciones menores son aquellas que pueden, o no, producir una disminución en el funcionamiento del implante, pero que se resuelven de manera espontánea o con tratamiento conservador, sin necesidad de realizar una nueva intervención quirúrgica, e incluyen: dolor local, tinnitus, vértigo, alteraciones del gusto, infección, fístula de líquido cefalorraquídeo y parálisis facial. Las complicaciones mayores son aquellas que requieren reintervención quirúrgica o explante. Se logró recopilar la información de 172 pacientes, 88 (51,16%) de sexo masculino y 84 (48,83%) de sexo femenino, con unas edades entre los 3 y los 71 años promedio de 22,1 años. El porcentaje global de complicaciones fue del 22,67% incluyendo las complicaciones menores y mayores, que corresponde a 39 implantes. El porcentaje de fallos es de 3,4%, que representa un total de 6 implantes. El porcentaje de reimplantes es de 5,2% del total, que corresponden a 09 implantes, siendo la causa más común falla técnica del dispositivo (06), seguido por falla por impacto (03). En cuanto a las complicaciones, se presentaron 12 complicaciones mayores que corresponden al 6,97%. El porcentaje de complicaciones menores en nuestro estudio fue de 15,6% (27)...

The following study corresponds to a descriptive analysis in patients from the Hospital Universitario Clínica San Rafael, which received cochlear implant surgery between january/2000 and december/2010. It describes the incidence of minor and major complications in the cochlear implant surgery, with a minimum follow up of 12 months. The complications of the cochlear implant surgery are divided in to two main categories: minor and major ones. The minor complications are those that can, or cannot, produce a decrease in the performance of the implant; but resolves spontaneously or with medical treatment, without making any surgery. Its clue symptoms involve: local pain, tinnitus, vertigo, taste alterations, infections, CSF fistula and facial paralysis. The major complications require a second surgery intervention or explants. The clinical histories of 172 patients were obtained, in which 88 (51,16%) were men and 84 (48,83%) were women, all with ages that comes from 3 to 71 years giving an average of 22.1 years old. The percentage of global complications was of 22,67% included the minor and major complications, that correspond to 39 implants. The fail percentage is of 3,4%, representing a total of 6 implants. The re-implants percentage corresponds to 5,2% from 9 implants that were in total, leading to the main cause of technical device fail (06), following by a fail for an impact cause (03). There were 12 major complications presented that correspond to 6.97%. The percentage of minor complications on the following study was of 15,6% (27)...

Endolymphatic Hydrops: Pathophysiology and Etiology / 대한이비인후과학회지

Endolymphatic hydrops (EH) represents a histopathologic finding in which the structures bounding the endolymphatic space are distended by an enlargement of endolymphatic volume. EH primarily involves the cochlear duct and saccule but can involve the utricle and ampullae of the semicircular canals. EH is a consistent finding in patients with Meniere's disease, however, the reverse is not true. EH may occur as a consequence of a variety of disorders, including DFNA 9, Alport syndrome, serous labyrinthitis, suppurative labyrinthitis, otosyphilis, temporal bone fracture, surgical trauma, neoplasm, immune disorders, otosclerosis, or Paget's disease. The mechanism of development of hydrops is also unclear. This review provides information to understand the recent pathophysiologic mechanism and causal disoders in EH.

Audiometria de altas frequências no diagnóstico complementar em audiologia: uma revisão da literatura nacional / High-frequency audiometry in audiological complementary diagnosis: a revision of the national literature

A audiometria de altas frequências (AAF) é um exame audiológico importante na detecção precoce de perdas auditivas por lesões na base do ducto coclear. Nos últimos anos, a sua utilização foi facilitada pelo fato de os audiômetros comercializados passarem a incorporar frequências superiores a 8 kHz. Porém, existem diferenças relacionadas aos equipamentos utilizados, às metodologias empregadas e/ou aos resultados e interpretação. Assim, o objetivo deste artigo foi analisar a produção científica nacional sobre a aplicação clínica com AAF, para compreender sua utilização atual. Foram pesquisados textos publicados e indexados nas bases de dados LILACS, SciELO e Medline, num período de tempo de dez anos, utilizando como descritor audiometria de altas frequências/high-frequency audiometry. Encontraram-se 24 artigos científicos nacionais utilizando AAF, cuja população avaliada, em sua maioria, apresentava de 18 a 50 anos de idade; 13 dos estudos determinaram os limiares utilizando como referência decibel nível de audição (dBNA); alguns estudos realizaram a comparação dos limiares auditivos tonais entre grupos para definir a normalidade; os autores relataram diferenças significativas nos limiares auditivos de altas frequências entre as idades. A AAF é utilizada na clínica audiológica para identificação precoce de alterações auditivas e no acompanhamento da audição de sujeitos expostos a drogas ototóxicas e/ou agentes otoagressores.

High-frequency audiometry (HFA) is an important audiological test for early detection of hearing losses caused by leasions in the base of the cochlear duct. In recent years, its use was facilitated because audiometers began to identify frequencies higher than 8 kHz. However, there are differences related to the equipment used, the methodologies followed, and/or to the results and their interpretation. Therefore, the aim of this study was to analyze the national scientific production regarding HFA clinical application, to better understand its current use. Articles published and indexed in LILACS, SciELO and Medline databases in the last ten years were researched, using as keyword audiometria de alta frequência/high-frequency audiometry. Twenty-four Brazilian scientific papers using HFA were found; most studies evaluated participants with ages ranging from 18 to 50 years; 13 studies used decibel hearing level (dBHL) to determine the thresholds; a few studies compared tonal auditory thresholds between groups to define normality; the authors reported significant differences in high frequency auditory thresholds among age ranges. HFA is used in audiological clinic for early identification of auditory alterations and in the auditory follow-up of subjects exposed to ototoxic drugs and/or otoagressive agents.

Identification of genes concordantly expressed with Atoh1 during inner ear development / 대한해부학회지

The inner ear is composed of a cochlear duct and five vestibular organs in which mechanosensory hair cells play critical roles in receiving and relaying sound and balance signals to the brain. To identify novel genes associated with hair cell differentiation or function, we analyzed an archived gene expression dataset from embryonic mouse inner ear tissues. Since atonal homolog 1a (Atoh1) is a well known factor required for hair cell differentiation, we searched for genes expressed in a similar pattern with Atoh1 during inner ear development. The list from our analysis includes many genes previously reported to be involved in hair cell differentiation such as Myo6, Tecta, Myo7a, Cdh23, Atp6v1b1, and Gfi1. In addition, we identified many other genes that have not been associated with hair cell differentiation, including Tekt2, Spag6, Smpx, Lmod1, Myh7b, Kif9, Ttyh1, Scn11a and Cnga2. We examined expression patterns of some of the newly identified genes using real-time polymerase chain reaction and in situ hybridization. For example, Smpx and Tekt2, which are regulators for cytoskeletal dynamics, were shown specifically expressed in the hair cells, suggesting a possible role in hair cell differentiation or function. Here, by reanalyzing archived genetic profiling data, we identified a list of novel genes possibly involved in hair cell differentiation.

Expression of Aquaporin-2 in the Inner Ear of Water-Deprived Guinea Pigs / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Although the role of aquaporin-2 (AQP2) in the kidney has been well defined, its role in the inner ear remains to be determined. The present study was to investigate the effect of water deprivation on the expression of AQP2 in the inner ear. MATERIALS AND METHOD: Healthy male guinea pigs weighing 250 g were used. The experimental group underwent water restriction and the control underwent water loading with sucrose-containing water for 3 days. Concentrations of plasma arginine-vasopressin (AVP) were determined and electrocochleography (ECoG) recordings were made. An RT-PCR, real-time PCR and Westernblotting analysis were used for quantitative analysis of AQP2 mRNA and AQP2 protein expression. Immunohistochemistry was also used to evaluate the distribution of AQP2 water channel proteins in the inner ear. RESULTS: AQP2 was mainly expressed in the epithelium of endolymphatic sac, spiral limbus, spiral ligament and stria vascularis of scala media. The concentrations of plasma AVP were 9.2+/- 0.8 pg/mL in the experimental group and 0.78+/-0.3 pg/mL in the control. The summation potential/ action potential (SP/AP) ratio in ECoG was markedly increased in the experimental group (0.55 in the experimental and 0.29 in the control). RT-PCR and real time PCR as well as Western blot analysis showed that the level of AQP2 mRNA and protein in the cochlea and endolymphactic sac of the water-deprived group was significantly higher than those in the control group. CONCLUSION: These data suggest that AQP2 is one of the important water channels in fluid homeostasis in the inner ear. Moreover, the volume of endolymphatic space can be increased via AVP-AQP2 system in response to water deprivation.

Morphologic Change of the Vestibular Organ in the Na+-K+-2Cl- Cotransporter Deficiency Mouse

BACKGROUND AND OBJECTIVES: The Na+-K+-2Cl- cotransporter-1 (NKCC1) is a member of the cation-coupled chloride transporter that participates in salt transport and cell volume regulation in diverse tissues. NKCC1 deficient mice exhibit deafness, and have structural alterations in the cochlea. In addition to hearing loss, NKCC1-deficient mice show a shaker-waltzer behavior, which suggests a vestibular system defect. This study investigated the morphology of the vestibular system of NKCC1-deficient mice. In addition, this study evaluated whether NKCC1 mRNA and its protein are expressed in human vestibular end organs. MATERIALS AND METHOD: NKCC1-deficient and wild type mice aged 4~5 weeks were sacrificed. Their heads were cut in the midsagittal plane, fixed and decalcified. For light microscopy, 5 m sections were cut, and stained with hematoxylin and eosin. Human vestibular end organs were harvested during acoustic tumor surgery via translabyrinthine approach. Some of these end organs were used for the total mRNA extraction and the remainder was used for immunostaining. RT-PCR was performed for NKCC1. RESULTS: The scala media of the cochlear of the NKCC1-deficient mice were collapsed but the bony labyrinth of the cochlea appeared unaffected. However, the semicircular canals (SCCs) were much smaller than those in the wild type. Furthermore, the SCCs were completely missing in some NKCC1-deficient mice. NKCC1 mRNA was expressed in both human macula and crista ampullaris and its protein was expressed mainly in the transitional and dark cell area of the human crista ampullaris. CONCLUSION: NKCC1 may be essential for maintaining the vestibular morphology and its function in mice and NKCC1 is well expressed in human vestibular end organs.

Morphologic Change of the Vestibular Organ in the Na+-K+-2Cl- Cotransporter Deficiency Mouse

BACKGROUND AND OBJECTIVES: The Na+-K+-2Cl- cotransporter-1 (NKCC1) is a member of the cation-coupled chloride transporter that participates in salt transport and cell volume regulation in diverse tissues. NKCC1 deficient mice exhibit deafness, and have structural alterations in the cochlea. In addition to hearing loss, NKCC1-deficient mice show a shaker-waltzer behavior, which suggests a vestibular system defect. This study investigated the morphology of the vestibular system of NKCC1-deficient mice. In addition, this study evaluated whether NKCC1 mRNA and its protein are expressed in human vestibular end organs. MATERIALS AND METHOD: NKCC1-deficient and wild type mice aged 4~5 weeks were sacrificed. Their heads were cut in the midsagittal plane, fixed and decalcified. For light microscopy, 5 m sections were cut, and stained with hematoxylin and eosin. Human vestibular end organs were harvested during acoustic tumor surgery via translabyrinthine approach. Some of these end organs were used for the total mRNA extraction and the remainder was used for immunostaining. RT-PCR was performed for NKCC1. RESULTS: The scala media of the cochlear of the NKCC1-deficient mice were collapsed but the bony labyrinth of the cochlea appeared unaffected. However, the semicircular canals (SCCs) were much smaller than those in the wild type. Furthermore, the SCCs were completely missing in some NKCC1-deficient mice. NKCC1 mRNA was expressed in both human macula and crista ampullaris and its protein was expressed mainly in the transitional and dark cell area of the human crista ampullaris. CONCLUSION: NKCC1 may be essential for maintaining the vestibular morphology and its function in mice and NKCC1 is well expressed in human vestibular end organs.

Morphological Changes of Cochlear Structures after Cisplatin Administration / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Cisplatin is frequently used in the treatment of various forms of malignancies. It's therapeutic efficacy, however, is limited due to the occurrence of sensorineural hearing loss. Little is known about the course of hearing loss after cessation of cisplatin administration. We observed the cochlear duct morphology with normal and cisplatin treated animals. MATERIALS AND METHODS: Healthy rats (strain Sprague-Dawly, weighting 80-100 mg) were used for all experiments. Total 15 rats were selected. They were divided into two groups, a treated group and a control. Four survival groups (n=3, respectively) were assigned as the treated group. After treatment with cisplatin, each survival group was sacrificed 1, 4, 10, 20 days. Except for the normal control (n=3), twelve animals were treated with cisplatin by daily I.P. injection of 1.5 mg/kg for 8 consecutive days. RESULTS: One day after cessation of cisplatin administration, outer hair cells (OHCs) loss and stria vascularis were degenerated especially in the basal turn. At 4, 10, 20 days, the OHCs and stria vascularis morphology of the survival group were similar to those of the survival group at one day. CONCLUSION: Our findings suggest cisplatin ototoxicity is predominantly involved in the basal turn of cochlear duct. This finding was significantly correlated with high frequency hearing loss of cisplatin ototoxicity.

Imágenes en anatomía coclear TC y RM / Cochlear anatomy CT and MR imaging

Los autores ofrecen un breve repaso de anatomía normal de la cóclea con imágenes de TC y RM a fin de posibilitar una más acabada identificación de hallazgos patológicos en pacientes con hipoacusia perceptiva

Estudio descriptivo asobre la evolución madurativa de la función latencia-intensidad a la onda y su valor en el diagnóstico diferencial objetivo de las hipoacusias / Description study about the evolution madurative of the function latent-intensity to the wave and his value in the diferential diagnostic objective of the hypoacusias

El propósito del trabajo es el de estudiar la evolución madurativa de la función latencia-intensidad a la onda V, evaluar su valor en el diagnóstico diferencial objetivo de las hipoacusias, y también determinar su comportamiento en pacientes normales y con hipoacusia, obteniendo de esta forma myor conocimiento e información sobre esta función de los Potenciales Evocados Auditivos de Trono Cerebral (P.E.A.T.C). Las variables consideradas son evolución madurativa de la función latencia-intensidad a la onda V y valor en el diagnóstico diferencial objetivo de las hipoacusias. Se trabaja con una muestra constituída por 377 casos (oídos) con audición normal, hipocusia de conducción, coclear y retrocolear que se registran entre el mes de Enero del año 1991 hasta Mayo de 1997, en los archivos del Instituto de Neurociencias San Lucas de la ciudad de Rosario. El tipo de estudio es descriptivo, longitudinal y ex-post-facto. Las conclusiones a las que se arriban son que, la función latencia-intensidad estimada, muestra los cambios madurativos: los valores de latencia van disminuyendo desde el nacimiento hasta alcanzar los valores de latencia adultos. Estos se obtienen a la edad comprendida entre mayores de un ño y hasta dos años. La función latencia-intensidad presenta un desplazamiento en forma gradual y el comportamiento no se encuentra alterado debido a que el mismo es similar en todas las edades. El valor de la función latencia-intensidad estimada es el de poder utilizarla en el diagnóstico diferencial objetivo de las hipoacusias con un determinado nivel de confianza

El órgano auditivo de la lagartija Sceloporus torcuatus: estudio anatómico y funcional / The hearing organ of lizard Sceloporus torcuatus: an anatomical and physiological study

Se hace una breve descripción de la anatomía del oído externo y de la fisiología auditiva de Sceloporus torcuatus. Se señala que la depresión formada por el conducto auditivo externo esta parcialmente cubierta por escamas de mayor tamaño que las normales, las que además tienen forma diferente al resto de las escamas de la región, por lo que se les dio un nombre especial, denominándolas escamas frontales del oído externo. Se describe detalladamente el conducto coclear, poniendo énfasis en la histología del mismo. También se describen algunos epitelios, tales como los de la papila basilar (órgano de la audición), las manchas de la lagena y la pared vestibular del conducto coclear, esta última se ha considerado en otros reptiles como tejido secreto. La similitud morfológica entre la pared vestibular del conducto coclear de esta especie, la estría vascular de los mamíferos y el tegumento vasculoso de las aves, sugiere semejanzas funcionales de estas estructuras. Se usaron potenciales evocados auditivos del tallo cerebral para estudiar esta especie reptiliana. Se encontró (con clics) el umbral de potenciales de estímulos auditivos a 40 dB

Early development of the spiral ganglion and organ of corti in albino rat embryos

This work was done to study the early development of the spiral ganglion and the cochlear duct in albino rat embryos in an attempt to clarify the relation between the cytodifferentiation of the organ of Corti and its innervation. Thirty rat embryos ranging in age from 12.5 days to full-term, were used in this study. The results of this work suggest a notion of a double origin of the spiral ganglion from both neural crest and otocyst and also support the tonotopic organization of the central auditory pathway explaining the tonotopic processing of the complex sounds. Moreover, the neural crest throughout the prenatal period continues to contribute schwannoblasts to the spiral ganglion and their peripheral and central nerve projections initiating the early myelination of the auditory pathway. On the other hand, the results of this work indicate that the whole cochlear duct is developed from a single mitotic center located on the anteromedial wall of otocyst. The rapid growth and coiling of the cochlear duct occurs at the early stages of development as a result of the early innervation of the anteromedial wall of otocyst through the mitotic center. The subsequent innervation of the presumptive sensory cells within the medial wall of the completely coiled cochlear duct usually associated with the early appearance of undifferentiated multilayered organ of Corti. In later stages of development, the maturation of the spiral ganglion and organ of Corti seems to follow a sequential and interdependent process of differentiation related to: 1] stratification of the peripheral and central nerve projections; 2] mesenchymal clearance of perilymphatic spaces and formation of the scala vestibuli and scala tympani; 3] maturation of Reissner's membrane, stria vascularis and spiral lamina. Concerning formation of the tectorial membrane, the results of this work point out to the involvement of the cells of the great epithelial ridge in secretion of the main portion of the tectorial membrane. However, the cells of the small epithelial ridge represent a minor source for secretion of the tectorial membrane at its early stages of development

Daño auditivo inducido por ruido: revisión en 90 pacientes de alto riesgo / Noise induced injury. A 90 patients survey

Se estudiaron 90 pacientes expuestos a ambiente ruidoso, sin protección auditiva. Fueron clasificados en tres grupos: El primero con exposición hasta 60 decibeles, el segundo entre 60 y 90 decibeles y el tercero con exposición superior a los 90 decibeles. En el grupo I no se encontraron pacientes con daño auditivo. En el grupo 2 registro un 12.5 por ciento de incidencia de trauma acústico. En el grupo 3 se detectó un 46.6 por ciento de incidencia de trauma acústico. Con base en estos datos, concluimos que el daño auditivo tiene una relación directa con la intensidad del ruido. La susceptibilidad individual es otro factor determinante para el desarrollo de estas lesiones

Intoxicación del oído interno con gentamicina en la hidropesía endolinfática / Inner ear intoxication with gentamicyn in endolymphatic hydrops

Se presenta la experiencia clínica en la intoxicación del oído interno con gentamicina en 10 enfermos portadores de hidropesía edolinfática invalidante. A todos los enfermos se les instiló sulfato de gentamicina en el oído medio en dosis que varían entre 6 y 72 mg con un promedio de 27.1 mg. El 90 por ciento de ellos tuvo un buen resultado, quedando el 60 por ciento asintomático y un 30 por ciento con sintomatología mínima. El otro 10 por ciento no mejoró, permaneciendo su sintomatología sin variación. La audición cayó entre 10 y 20 dB en un 30 por ciento de los pacientes. No hubo cofosis por el tratamiento. En el largo plazo estos buenos resultados no varían

Resultados de la detección de anticuerpos anticocleares en diversas patologías del oído / Results of anticochlear antibodies detection in some ear diseases

Se presentan los resultados de aplicar un método de detección de anticuerpos anticocleares a 212 persona, 186 de ellas portadoras de hipoacusias atribuída a diversos cuadros clínicos y 26 normales. Se empleó la técnica de inmunofluorescencia indirecta, utilizando como antígeno material membranosoobtenido del conducto coclear humano de cadáveres frescos con menos de 6 horas de deceso. En 31 hipoacusias sensorioneurales, de las cuales 24 tenían un inicio y curso clínico que indicaban una posible etiología autoinmune y 7 que se presentaban asociadas a un cuadro sistémico de reconocida etiología autoinmune, la positividad en la detección de anticuerpos anticocleares se encontró en 17 de ellas (54.8 por ciento ). En 25 hipoacusias catalogadas como hidropesías endolinfáticas retardadas sean ipsi como contralaterales, la prueba fue positiva en 13 (52 por ciento ). En estos dos grupos los porcentajes son significativamente semejantes lo que sugiere una etipatogenia similar (p<0.01). En 47 hidropesias endolinfáticas idiopáticas o enfermedad de Meniere la prueba fue positiva en 12 (25.5 por ciento ). En 26 pacientes que presentaron una sordera súbita sensorioneural la prueba fue positiva en 8 (32 por ciento ). Otros 42 pacientes portadores de una hipoacusia sensorioneural no clasificable tuvieron una prueba positiva en 8 de ellos (19 por ciento ). La prueba fue también positiva en 2 de 8 hipoacusias consideradas congénitas y en 2 de 4 otoesclerosis. Cuatro hipoacusias consideradas como presbiacusia tuvieron la prueba negativa. Ninguno de los 26 sujetos sanos presentó la prueba positiva. Esto significa que la prueba de detección de anticuerpos anticocleares tiene una sensibilidad de 54.8 por ciento , una especificidad de 100 por ciento , un valor predictivo positivo de 100 por ciento y un valor predictivo negativo de 65 por ciento . Se concluye que no sólo la denominada enfermedad autoinmune del oído interno sería atribuíble a un fenómeno de autoinmunidad, sino que otros cuadros clínicos podrían tener una etiopatogenia similar