Cribado auditivo mediante potenciales evocados auditivos de estado estable obtenidos por estimulación simultánea de la vía aérea y la ósea / Hearing screening using auditory steady state responses obtained by simultaneous air- and bone-conduction stimuli

Introducción y objetivos: Minimizar los falsos positivos constituye un objetivo de los programas de cribado auditivo universal. Una manera de lograrlo sería diferenciar entre los trastornos neurosensoriales (verdaderos positivos) y los conductivos transitorios (falsos positivos) mediante un método que permita estudiar la respuesta del sistema auditivo ante la estimulación tanto por vía aérea como por vía ósea. El objetivo de este trabajo es evaluar la eficiencia diagnóstica de una prueba automatizada de cribado basada en el registro de potenciales evocados auditivos de estado estable obtenidos por estimulación simultánea de vía aérea y vía ósea. Métodos: Se estudiaron 80 bebés menores de 2 meses de edad. A todos se les realizó la prueba de cribado, siendo posteriormente citados para el estudio confirmatorio, cuyo resultado se consideró como criterio de verdad del estado audiológico del bebé. Resultados: Con esta prueba se obtuvo una eficiencia diagnóstica equivalente (un 100% de sensibilidad y un 97,7% de especificidad) a la reportada para otras pruebas utilizadas en el cribado (emisiones otoacústicas y potenciales evocados de tronco cerebral), con la ventaja adicional de que la introducción de la vía ósea en el cribado permitió reducir la cifra de falsos positivos del 13,3 al 2,2%. La duración de la prueba fue de 5,3 (± 1,9) min, siendo suficiente en el 34% de los casos una sola repetición para llegar al resultado. Conclusiones: Esta prueba automatizada de cribado basada en el registro de potenciales evocados auditivos de estado estable permitió discriminar entre los trastornos conductivos transitorios y los neurosensoriales, reduciendo así los falsos positivos y elevando la eficiencia diagnóstica de esta metodología (AU)

Introduction and objectives: Minimising false positives rates is an important goal of universal newborn hearing screening programmes. An adequate way for reaching that goal could be differentiating between transient conductive hearing losses (false positives) and permanent sensorineural hearing impairments (true positives) by means of a methodology that studies electrophysiological responses obtained using both air- and bone-conduction stimuli. Our objective was to evaluate the efficiency of an automated hearing screening test based on auditory steady state responses obtained using simultaneous air- and bone-conduction stimuli. Methods: A sample of 80 high risk babies lees than 2 months of born were screened using the automatic screening test. A confirmatory clinical and electrophysiological evaluation was used as the gold standard. Results: The estimated diagnostic efficiency of this screening test was equivalent (100% sensitivity and 97.7% specificity) to the efficiency reported for otoacoustic emissions and automated auditory brainstem responses. The introduction of bone conduction in the screening reduced the false positive rate from 13.3% to 2.2%. The test duration was 5.3 (± 1.9) min. In 34% of babies only one repetition of the test was needed to raising the result. Conclusions: The screening test performed quite well in this initial clinical trial, differentiating transient conductive hearing losses from permanent neurosensory impairments and improving the diagnostic efficiency of auditory steady state responses (AU)

Hearing screening using auditory steady state responses obtained by simultaneous air- and bone-conduction stimuli.

INTRODUCTION AND OBJECTIVES: Minimising false positives rates is an important goal of universal newborn hearing screening programmes. An adequate way for reaching that goal could be differentiating between transient conductive hearing losses (false positives) and permanent sensorineural hearing impairments (true positives) by means of a methodology that studies electrophysiological responses obtained using both air- and bone-conduction stimuli. Our objective was to evaluate the efficiency of an automated hearing screening test based on auditory steady state responses obtained using simultaneous air- and bone-conduction stimuli. METHODS: A sample of 80 high risk babies lees than 2 months of born were screened using the automatic screening test. A confirmatory clinical and electrophysiological evaluation was used as the gold standard. RESULTS: The estimated diagnostic efficiency of this screening test was equivalent (100% sensitivity and 97.7% specificity) to the efficiency reported for otoacoustic emissions and automated auditory brainstem responses. The introduction of bone conduction in the screening reduced the false positive rate from 13.3% to 2.2%. The test duration was 5.3 (± 1.9)min. In 34% of babies only one repetition of the test was needed to raising the result. CONCLUSIONS: The screening test performed quite well in this initial clinical trial, differentiating transient conductive hearing losses from permanent neurosensory impairments and improving the diagnostic efficiency of auditory steady state responses.

New system for neonatal hearing screening based on auditory steady state responses.

NEURONIC-A 6.0 is a system for objective detection of hearing loss by means of the recording and analysis of auditory steady state responses. The system generates digitally Amplitude Modulated tones of different frequencies, allowing the mix of these and the simultaneous presentation through different transducers (earphone and bone vibrator) at different intensities. The system also includes a procedure for artefacts rejection based on the trajectory of variation of the residual noise through time and quantitative indicators or statistics, calculated in the frequency domain, to control the acquisition of the response process and detect automatically the presence or absence of the same. The whole working procedure is automated, which means that once the recording has started, a final result can be obtained in binary form (pass or fail) without the intervention of the examiner.

Cross-modal plasticity in deaf child cochlear implant candidates assessed using visual and somatosensory evoked potentials.

INTRODUCTION: Cross-modal plasticity has been extensively studied in deaf adults with neuroimaging studies, yielding valuable results. A recent study in our laboratory with deaf-blind children found evidence of cross-modal plasticity, revealed in over-representation of median nerve somatosensory evoked potentials (SEP N20) in left hemisphere parietal, temporal and occipital regions. This finding led to asking whether SEP N20 changes are peculiar to deaf-blindness or are also present in sighted deaf children. OBJECTIVE: Assess cross-modal plasticity in deaf child cochlear implant candidates using neurophysiological techniques (visual evoked potentials and median nerve somatosensory evoked potentials). METHODS: Participants were 14 prelingually deaf children assessed in the Cuban Cochlear Implant Program. Flash visual-evoked potentials and SEP N20 were recorded at 19 scalp recording sites. Topographic maps were obtained and compared to those of control group children with normal hearing. Analysis took into account duration of hearing loss. RESULTS: Topographic maps of flash visual-evoked potentials did not show changes in deaf child cochlear implant candidates. However, SEP N20 from right median nerve stimulation did show changes from expansion of cortical activation into the left temporal region in deaf children aged ≥7 years, which was interpreted as neurophysiological evidence of cross-modal plasticity, not previously described for this technique and type of somatosensory stimulus. We interpret this finding as due in part to duration of deafness, particularly related to handedness, since expansion was selective for the left hemisphere in the children, who were all right-handed. CONCLUSIONS: Cortical over-representation of SEP N20 in the left temporal region is interpreted as evidence of cross-modal plasticity that occurs if the deaf child does not receive a cochlear implant early in life-before concluding the critical period of neural development-and relies on sign language for communication.

Cambios con la edad en la respuesta electrofisiológica de seguimiento a la modulación del estímulo acústico / Maturational changes in the human envelope-following responses

Introducción: La capacidad de detectar cambios temporales en la amplitud de modulación de los sonidos del habla es esencial para el adecuado desarrollo y comprensión del lenguaje. El potencial evocado auditivo de seguimiento a la envolvente (PEA-SE) permite estudiar objetivamente la respuesta auditiva a los cambios en la modulación del estímulo acústico en sujetos que no cooperan con exámenes conductuales. Objetivo: Evaluar posibles cambios maduracionales en los parámetros del PEA-SE durante los 2 primeros años de vida. Métodos: se estudiaron 16 bebés normooyentes (12 recién nacidos y 4 bebés de 2 años de edad). Se registró el PEA-SE obtenido con un ruido blanco al que se le realizó un barrido continuo de modulación entre 20-200Hz a 50dB HL. Resultados: Las principales diferencias con respecto al patrón morfológico descrito en los adultos estuvieron a expensas de las frecuencias inferiores a 50Hz, donde el componente P1, a diferencia del P2, no se registró de forma definida y estable en ninguno de los grupos. Con la edad existe, además, un incremento significativo en la amplitud y detectabilidad del potencial en todas las frecuencias de modulación estudiadas. Conclusiones: Se caracterizan por primera vez las modificaciones del PEA-SE con la maduración del sistema auditivo en seres humanos. Los resultados sugieren que el PEA-SE obtenido entre 80-200Hz podría ser útil para estudiar los cambios maduracionales del procesamiento auditivo temporal en la población infantil(AU)

Introduction: The auditory ability to discriminate rapid changes in the envelope of language sounds is essential for speech comprehension. Human envelope-following responses (EFRs) are useful for objective measurement of temporal auditory processing in subjects who are unable to give accurate behavioural responses (e.g., young children). Objective: To evaluate age-dependent changes in EFRs during the first 2 years of life. Methods: The EFRs were recorded in a sample of 16 well babies distributed into 2 age groups (G1: 12 newborns; G2: 4 babies of 2 years). The EFRs were evoked by white noise carrier stimuli with a sweep of modulation frequencies from 20 to 200Hz presented at 50dB HL. Results: The age-related changes affected both morphology and EFR detectability. The main morphological differences were at the expense of frequencies below 50Hz, where the first component P1 was not well defined in either of the 2 age groups. For all modulation frequencies, age significantly affected EFR amplitude and detectability. Conclusions: The present study provides the first evidence on EFR maturation. Some understanding of normal EFR development would facilitate a better use of this technique in clinically-objective measurement of auditory temporal processing in infants who cannot provide reliable behavioural responses(AU)

Cross-modal plasticity in Cuban visually-impaired child cochlear implant candidates: topography of somatosensory evoked potentials.

INTRODUCTION: Studies of neuroplasticity have shown that the brain's neural networks change in the absence of sensory input such as hearing or vision. However, little is known about what happens when both sensory modalities are lost (deaf-blindness). Hence, this study of cortical reorganization in visually-impaired child cochlear implant (CI) candidates. OBJECTIVE: Assess cross-modal plasticity, specifically cortical reorganization for tactile representation in visually-impaired child CI candidates, through study of topography of somatosensory evoked potentials (SEP). METHODS: From April through September 2005, SEP from median and tibial nerve electrical stimulation were studied in 12 visually-impaired child CI candidates aged 3-15 years and 23 healthy controls. Following placement of 19 recording electrodes using the International 10-20 System , SEP were recorded and then processed. Topographic maps were obtained for SEP N20 (median nerve) and SEP P40 (tibial nerve), permitting assessment of cortical reorganization by comparing visually-impaired, deaf children's maps with those of healthy children by means of visual inspection and statistical comparison using a permutation test. RESULTS: SEP N20 topography was significantly more extensive in visually-impaired child CI candidates than in healthy children. An asymmetrical pattern occurred from the expansion of hand tactile activation into the temporal and occipital regions in the left hemisphere on right median nerve stimulation. This did not occur for SEP P40 on tibial nerve stimulation (right and left). Magnitude of expanded SEP N20 response was related to severity of visual impairment and longer duration of dual sensory loss. CONCLUSIONS: Changes in SEP N20 topography are evidence of cross-modal plasticity in visually-impaired child CI candidates, appearing to result from a complex interaction between severity of visual impairment and duration of multisensory deprivation.

Maturational changes in the human envelope-following responses.

INTRODUCTION: The auditory ability to discriminate rapid changes in the envelope of language sounds is essential for speech comprehension. Human envelope-following responses (EFRs) are useful for objective measurement of temporal auditory processing in subjects who are unable to give accurate behavioural responses (e.g., young children). OBJECTIVE: To evaluate age-dependent changes in EFRs during the first 2 years of life. METHODS: The EFRs were recorded in a sample of 16 well babies distributed into 2 age groups (G1: 12 newborns; G2: 4 babies of 2 years). The EFRs were evoked by white noise carrier stimuli with a sweep of modulation frequencies from 20 to 200 Hz presented at 50 dB HL. RESULTS: The age-related changes affected both morphology and EFR detectability. The main morphological differences were at the expense of frequencies below 50 Hz, where the first component P1 was not well defined in either of the 2 age groups. For all modulation frequencies, age significantly affected EFR amplitude and detectability. CONCLUSIONS: The present study provides the first evidence on EFR maturation. Some understanding of normal EFR development would facilitate a better use of this technique in clinically-objective measurement of auditory temporal processing in infants who cannot provide reliable behavioural responses.

Localización de los generadores cerebrales del potencial evocado auditivo de estado estable a múltiples frecuencias moduladas a 40 hertzios / Brain sources localizing of multiple frequency auditory steady state response modulated at 40 hertz

Se estudiaron las bases neurales involucradas en la generación de los potenciales evocados auditivos de estado estable, obtenidos por estimulación con tonos modulados en amplitud a 40 hertzios de múltiples frecuencias, para lo cual se diseñó un protocolo de registro de alta resolución espacial, se aplicó el método bayesiano para estimar sus neurogeneradores y se definieron restricciones a priori para focalizar el cálculo inicial de las áreas de activación primaria al sistema auditivo. Los resultados logran activar fuentes generadoras a nivel del lóbulo temporal superior de ambos hemisferios; pero la activación cortical no es simétrica y se registra un efecto de lateralización interhemisférica, con activación del lóbulo temporal superior contralateral al oído estimulado en respuesta a tonos de 500 hertzios, mientras que para los tonos de 4 000 hertzios, el nivel de activación cortical es máximo a nivel del lóbulo temporal superior ipsilateral al oído estimulado. Los presentes resultados obtienen una nueva metodología para la evaluación del sistema auditivo, que puede ser aplicada en la caracterización de la reorganización cortical y neuroplasticidad en hipoacusias neurosensoriales severas y otras deprivaciones sensoriales.

The involved neural bases were studied in the generation of the auditory steady state response, obtained by stimulation with 40 hertz multiple frequency amplitude modulate tones, for which a high space resolution registration protocol was designed, the Bayes`method was applied to estimate their neurogenerators and restrictions were previously defined to focus the initial calculation from the primary activation areas to the auditory system. The results are able to detect generating sources at the level of the upper temporal lobe of both hemispheres; but the cortical activation is not symmetrical and an interhemispheric lateralization effect is registered, with activation of the contralateral upper temporal lobe to the stimulated ear as a response to tones of 500 hertz, while for the tones of 4 000 hertz, the cortical activation level is higher at the level of the ipsilateral upper temporal lobe to the stimulated ear. The present results obtain a new methodology for the evaluation of the auditory system that can be applied in the characterization of the cortical reorganization and neuroplasticity in severe neurosensory hearing loss and other sensory deprivations.

Localización de los generadores cerebrales del potencial evocado auditivo de estado estable a múltiples frecuencias moduladas a 40 hertzios / Brain sources localizing of multiple frequency auditory steady state response modulated at 40 hertz

Se estudiaron las bases neurales involucradas en la generación de los potenciales evocados auditivos de estado estable, obtenidos por estimulación con tonos modulados en amplitud a 40 hertzios de múltiples frecuencias, para lo cual se diseñó un protocolo de registro de alta resolución espacial, se aplicó el método bayesiano para estimar sus neurogeneradores y se definieron restricciones a priori para focalizar el cálculo inicial de las áreas de activación primaria al sistema auditivo. Los resultados logran activar fuentes generadoras a nivel del lóbulo temporal superior de ambos hemisferios; pero la activación cortical no es simétrica y se registra un efecto de lateralización interhemisférica, con activación del lóbulo temporal superior contralateral al oído estimulado en respuesta a tonos de 500 hertzios, mientras que para los tonos de 4 000 hertzios, el nivel de activación cortical es máximo a nivel del lóbulo temporal superior ipsilateral al oído estimulado. Los presentes resultados obtienen una nueva metodología para la evaluación del sistema auditivo, que puede ser aplicada en la caracterización de la reorganización cortical y neuroplasticidad en hipoacusias neurosensoriales severas y otras deprivaciones sensoriales(AU)

The involved neural bases were studied in the generation of the auditory steady state response, obtained by stimulation with 40 hertz multiple frequency amplitude modulate tones, for which a high space resolution registration protocol was designed, the Bayes`method was applied to estimate their neurogenerators and restrictions were previously defined to focus the initial calculation from the primary activation areas to the auditory system. The results are able to detect generating sources at the level of the upper temporal lobe of both hemispheres; but the cortical activation is not symmetrical and an interhemispheric lateralization effect is registered, with activation of the contralateral upper temporal lobe to the stimulated ear as a response to tones of 500 hertz, while for the tones of 4 000 hertz, the cortical activation level is higher at the level of the ipsilateral upper temporal lobe to the stimulated ear. The present results obtain a new methodology for the evaluation of the auditory system that can be applied in the characterization of the cortical reorganization and neuroplasticity in severe neurosensory hearing loss and other sensory deprivations(AU)

Criterio de parada de la promediación de la respuesta auditiva de estado estable / Stopping criteria for averaging the multiple auditory steady-state response

Introducción y objetivos: El presente estudio pretende examinar la eficiencia de la técnica de promediación para obtener potenciales evocados auditivos de estado estable en sujetos normoyentes y proveer de un criterio de parada cuantitativo a intensidades cercanas al umbral de audibilidad. Métodos: Una mezcla de 4 tonos continuos (500, 1.000, 2.000 y 4.000 Hz) modulados en amplitud entre 89 y 115 Hz, fueron simultáneamente presentados a ambos oídos a una intensidad de 40 dB HL. Fueron promediados un total de 128 segmentos de registro (23,9 min). Resultados: La técnica de promediación aunque resultó eficiente en la mayoría de los casos, no siempre pudo extraer la señal, incluso después de promediarse durante un período prolongado de tiempo. Se propuso además un análisis del ruido de fondo basado en la evaluación de la varianza del ruido en la vecindad de la señal. Conclusiones: Se proponen parámetros cuantificables para ayudar a establecer un criterio deparada de la promediación durante el registro de los potenciales evocados auditivos de estado estable (AU)

Introduction and objectives: The aim of this study was to examine the efficiency of the averaging technique for estimating multiple auditory steady state responses in normal hearing subjects and to provide quantifiable stopping criteria at near-threshold intensities. Methods: Multiple amplitude-modulated (89-115 Hz) tones (500, 1,000, 2,000 and 4,000 Hz) were simultaneously presented to both ears at a fixed intensity of 40 dB HL. A total of 128 data epochs were averaged (23.9 minutes).Results: The results showed that ‘‘classic’’ ensemble averaging, although accurate and time efficient in most cases, could not extract all near-threshold MSSR from noise, even after recording a considerable number of sweeps. The present study also proposed a different approach to evaluate the background noise based on evaluating the mean of the variance close to the signal. Conclusions: The study proposed quantitative parameters to establish stopping criteria during auditory steady-state recordings (AU)

[Stopping criteria for averaging the multiple auditory steady-state response]. / Criterio de parada de la promediación de la respuesta auditiva de estado estable.

INTRODUCTION AND OBJECTIVES: The aim of this study was to examine the efficiency of the averaging technique for estimating multiple auditory steady state responses in normal hearing subjects and to provide quantifiable stopping criteria at near-threshold intensities. METHODS: Multiple amplitude-modulated (89-115 Hz) tones (500, 1,000, 2,000 and 4,000 Hz) were simultaneously presented to both ears at a fixed intensity of 40 dB HL. A total of 128 data epochs were averaged (23.9 minutes). RESULTS: The results showed that "classic" ensemble averaging, although accurate and time-efficient in most cases, could not extract all near-threshold MSSR from noise, even after recording a considerable number of sweeps. The present study also proposed a different approach to evaluate the background noise based on evaluating the mean of the variance close to the signal. CONCLUSIONS: The study proposed quantitative parameters to establish stopping criteria during auditory steady-state recordings.

Estudio neuropsicologico de niños de 8 a 15 años que presentan descargas paroxisticas subclinicas lateralizadas y bajo rendimiento escolar / Neuropsychological study od 8 to 15year-old children with lateralised sub-clinical paroxysmal discharges and poor academic achievement

Introducción. Se han observado descargas paroxísticas en niños no epilépticos que presentan, al mismo tiempo, trastornos de aprendizaje. Objetivos. En este trabajo nos proponemos determinar si dicha asociación entre descargas subclínicas (DSC) y trastornos de aprendizaje refleja déficit neuropsicológicos concretos y, particularmente, si los posibles déficit se definen en función del hemisferio cerebral en el que se localiza la actividad paroxística. Pacientes y métodos. Realizamos una evaluación neuropsicológica a 17 niños de edades comprendidas entre los 8 y los 15 años, con trastorno inespecífico del aprendizaje, que presentaban descargas paroxísticas subclínicas localizadas en el hemisferio izquierdo (nueve casos) o en el hemisferio derecho (ocho casos). Resultados. Los niños que presentaban la actividad paroxística en el hemisferio izquierdo obtuvieron resultados semejantes a los niños que la presentaban en el derecho, salvo en las pruebas que evalúan habilidades visoconstructivas, en las que sus puntuaciones fueron superiores, y en las pruebas sobre funciones ejecutivas, en las cuales mostraron déficit que no se observaron en los niños que presentaban, la actividad paroxística en el hemisferio derecho. Conclusiones. Interpretamos que la presencia de DSC en el hemisferio izquierdo refleja un proceso de maduración cerebral más lento o deficitario, que podría compensarse con un programa adecuado de intervención neuropsicológica

Estudio neuropsicologico de niños de 8 a 15 años que presentan descargas paroxisticas subclinicas lateralizadas y bajo rendimiento escolar / Neuropsychological study od 8 to 15year-old children with lateralised sub-clinical paroxysmal discharges and poor academic achievement

Introducción. Se han observado descargas paroxísticas en niños no epilépticos que presentan, al mismo tiempo, trastornos de aprendizaje. Objetivos. En este trabajo nos proponemos determinar si dicha asociación entre descargas subclínicas (DSC) y trastornos de aprendizaje refleja déficit neuropsicológicos concretos y, particularmente, si los posibles déficit se definen en función del hemisferio cerebral en el que se localiza la actividad paroxística. Pacientes y métodos. Realizamos una evaluación neuropsicológica a 17 niños de edades comprendidas entre los 8 y los 15 años, con trastorno inespecífico del aprendizaje, que presentaban descargas paroxísticas subclínicas localizadas en el hemisferio izquierdo (nueve casos) o en el hemisferio derecho (ocho casos). Resultados. Los niños que presentaban la actividad paroxística en el hemisferio izquierdo obtuvieron resultados semejantes a los niños que la presentaban en el derecho, salvo en las pruebas que evalúan habilidades visoconstructivas, en las que sus puntuaciones fueron superiores, y en las pruebas sobre funciones ejecutivas, en las cuales mostraron déficit que no se observaron en los niños que presentaban, la actividad paroxística en el hemisferio derecho. Conclusiones. Interpretamos que la presencia de DSC en el hemisferio izquierdo refleja un proceso de maduración cerebral más lento o deficitario, que podría compensarse con un programa adecuado de intervención neuropsicológica(AU)