Series en disnea. Parte 3. Mecanismos, copia eferente o descarga corolaria / Series on Dyspnea. Part 3. Mechanisms, efferent copy or corollary discharge

Todas las teorías sobre los mecanismos de generación de disnea tuvieron defensores y detractores e, interesantemente, con el desarrollo de sofisticadas técnicas neurofisiológicas y de imágenes funcionales ha sido posible jerarquizar cada uno de ellos. Todas han sobrevivido al paso del tiempo y ninguna puede explicar por sí sola la disnea en todas las situaciones clínicas, lo cual habla de la naturaleza compleja y multifactorial del fenómeno. El concepto de inadecuación tensión y longitud halló en las últimas décadas un sustento con nuevas evidencias a su favor. En particular, con el hallazgo de las vías involucradas y con la aplicación de conocimientos neurofisiológicos, la teoría de la inadecuación tensión y longitud se vería refinada con la descarga corolaria o copia eferente. Esta descarga corolaria o copia eferente es un atributo básico del sistema nervioso, que se encuentra en el reino animal, desde los invertebrados a los primates y en la especie humana. Este artículo está dedicado a la historia de la copia eferente y su incorporación como hipótesis para explicar la disnea, la más aceptada en la actualidad.

All the theories about the mechanisms of generation of dyspnea had defenders and detractors and, interestingly, with the development of sophisticated neurophysiological techniques and functional imaging, it has been possible to rank each one of them. All have survived the passage of time and none can singularly explain dyspnea in all clini cal situations, showing the complex and multifactorial nature of the phenomenon. The concept of length-tension inappropriateness has found support in recent decades with new evidence in its favor. Specially with the discovery of the pathways involved and with the application of neurophysiological knowledge, the length-tension inappropriate ness theory would be refined with the corollary discharge or efferent copy. This corol lary discharge or efferent copy is a basic attribute of the nervous system found in the animal kingdom, from invertebrates to primates and in the human species. This article is dedicated to the history of the efferent copy and its incorporation as a hypothesis to explain dyspnea, which is currently the most accepted one.

Hiperacusia en trastornos del espectro autista: una revisión de la literatura / Hyperacusis in autism spectrum disorders: a review of the literature

Resumen La hiperacusia se define como la intolerancia a ciertos sonidos cotidianos que causa angustia y discapacidad significativas en las actividades sociales, ocupacionales, recreativas y otras actividades cotidianas. Los sonidos pueden percibirse como incómodamente fuertes, desagradables, atemorizantes o dolorosos. Se encuentra presente en aproximadamente un 3% población general, y aumenta significativamente en trastornos del espectro autista (TEA), alcanzando entre un 15% a 40%. Los mecanismos fisiopatológicos no son del todo claros, pero se ha propuesto, una alteración en el funcionamiento de mecanismos reflejos y de regulación, tanto a nivel de la vía auditiva periférica, como central, incluyendo estructuras no relacionadas directamente con la vía auditiva. El siguiente texto tiene como objetivo analizar la relación entre hiperacusia y TEA, enfatizando en la frecuencia en que se presentan como comorbilidades, en los posibles mecanismos fisiopatológicos, y en actualizaciones en el abordaje diagnóstico y terapéutico. Se realiza una revisión bibliográfica cualitativa en Pubmed con artículos entre los años 2008-2020 utilizando los términos: "hyperacusis autism", "sistema olivococlear", arrojando 39 artículos, de los cuales se seleccionaron en base a la temática de cada uno, evaluada por los autores. A pesar de una significativa relación entre hiperacusia y TEA, los mecanismos fisiopatológicos de ambas patologías siguen siendo un misterio. Existen estudios que sugieren pruebas de screening no invasivas que relacionan ambas patologías, pero debido a los sesgos de selección, todavía no son factibles de usar en forma universal. El abordaje terapéutico ha sido poco explorado, y no se dispone de fármacos que hayan demostrado su efectividad, por el contrario, algunos de ellos empeoran la sintomatología. Se recomienda al tratante, seguir un camino largo, en conjunto con el paciente, donde las terapias no farmacológicas como la terapia cognitivo conductual han mostrado tener buenos resultados.

Abstract Hyperacusis is defined as intolerance to certain sounds that causes significant distress and disability in social, occupational, recreational and other activities. Sounds can be perceived as uncomfortably loud, unpleasant, frightening, or painful. It is present in approximately 3% of the general population, and increases significantly in autism spectrum disorders (ASD), between 15% and 40%. The pathophysiological mechanisms are not entirely clear, but an alteration in the functioning of reflex and regulatory mechanisms has been proposed, both at the peripheral and central auditory pathways, including structures not directly related to the auditory pathway. The therapeutic approach has been little explored as there are no drugs that have demonstrated their effectiveness, on the contrary, some of them worsen the symptoms. The practitioner is recommended to follow a long path, in conjunction with the patient, where non-pharmacological therapies such as cognitive behavioral therapy have been shown to have good results. The following text shows a review of the literature with articles referring to the subject between the years 2008-2019.

Efeito inibitório da via eferente auditiva no transtorno de processamento auditivo central / Auditory efferent inhibitory effect in central auditory processing disorder

RESUMO Objetivo verificar e comparar a ocorrência e magnitude do efeito inibitório da via auditiva eferente em crianças e adolescentes com processamento auditivo normal e alterado, identificando um valor de corte para uso na prática clínica. Métodos estudo prospectivo, com amostra composta por 30 crianças de 7 a 14 anos, sendo 15 com avaliação de processamento auditivo normal (grupo controle) e 15 com processamento auditivo alterado (grupo estudo). Ambos os grupos foram submetidos à anamnese e avaliados por meio dos testes de emissões otoacústicas evocadas por estímulos transientes na ausência e presença de ruído contralateral, avaliação audiológica básica e de processamento auditivo. Resultados houve menor ocorrência do efeito inibitório da via eferente no grupo estudo (p-valor=0,038). Os valores médios obtidos no grupo controle foram 0,71 na orelha direita e 0,87 na orelha esquerda e no grupo estudo, 0,55 na orelha direita e 0,41 na orelha esquerda. Os grupos controle e estudo diferiram de modo significativo na orelha esquerda. Conclusão houve redução do efeito inibitório da via eferente em crianças e adolescentes com transtorno de processamento auditivo, sugerindo alteração funcional do sistema eferente olivococlear medial. O valor que separou as crianças com e sem alteração do sistema eferente foi de 0,55 dB na prática clínica, com 70% de sensibilidade e 66,7% de especificidade.

ABSTRACT Purpose Verify and compare the occurrence and magnitude of the inhibitory effect of the efferent auditory pathway in children and adolescents with normal and auditory processing disorder, identifying a cutoff value to use in clinical settings. Methods A prospective study, with a total sample of 30 children aged 7 to 14 years, half with normal auditory processing assessment (Control Group) and the other half with auditory processing disorder (Study Group). Both groups were submitted to anamnesis and evaluated using the otoacoustic emissions tests evoked by transient stimuli in the absence and presence of contralateral noise, basic audiological evaluation and auditory processing. Results The study group presented a lower occurrence of the inhibitory effect of the efferent pathway when compared to the control group (p value=0.038). The mean values ​​obtained for the control group were 0.71 in the right ear and 0.87 in the left ear and for the study group, 0.55 in the right ear and 0.41 in the left ear. The two groups showed a statistically significant difference for the left ear. Conclusion There was a reduction in the inhibitory effect of the efferent pathway in children and adolescents with auditory processing disorder, suggesting a functional change in the medial olivocochlear efferent system. In this study, the cutoff value of 0.55 dB separated children with and without alteration of the efferent system with 70% sensitivity and 66.7% specificity.

Speech-in-noise perception ability can be related to auditory efferent pathway function: a comparative study in reading impaired and normal reading children / Capacidade de percepção da fala no ruído pode estar relacionada à função da via auditiva eferente: estudo comparativo de crianças com dificuldade de leitura e com leitura normal

Abstract Introduction: Deficient auditory processing can cause problems with speech perception and affect the development and evolution of reading skills. The efferent auditory pathway has an important role in normal auditory system functions like speech-in-noise perception, but there is still no general agreement on this. Objective: To study the performance of the efferent auditory system in a group of children with reading impairment in comparison with normal reading and evaluation of its relationship with speech-in-noise perception. Methods: A total of 53 children between the ages of 8-12 years were selected for the study of which 27 were with reading impairment and 26 were normal reading children. Transient evoked otoacoustic emissions suppression and auditory recognition of words-in-noise test were performed for all the children. Results: The average amplitude of transient evoked otoacoustic emissions suppression showed a significant difference between the two groups in the right (p = 0.004) and in the left ear (p = 0.028). Assessment of the relationship between transient evoked otoacoustic emissions suppression and monaural auditory recognition of words-in-noise scores showed a significant moderate negative relationship only in the right ear (p = 0.034, r = −0.41) of the normal reading children. Binaural auditory recognition of words-in-noise scores were significantly correlated with the amplitude of transient evoked otoacoustic emissions suppression in the right ear (p < 0.001, r = −0.75) and in the left ear (p < 0.001, r = −0.64) of normal reading children. In the reading impaired group, ?a weaker correlation was observed between binaural auditory recognition of words-in-noise scores and transient evoked otoacoustic emissions suppression in the right (p = 0.003, r = −0.55) and in the left ear (p = 0.012, r = −0.47). Conclusions: Transient evoked otoacoustic emissions suppression pattern in the reading impaired group was different compared with normal reading children, and this difference could be related to efferent system performance. Words-in-noise scores in children with impaired reading were lower than in normal reading children. In addition, a relationship was found between transient evoked otoacoustic emissions suppression and words-in-noise scores in both normal and impaired reading children.

Resumo Introdução: O processamento auditivo deficiente pode causar problemas na percepção da fala e afetar o desenvolvimento e a evolução das habilidades de leitura. A via auditiva eferente tem um papel importante nas funções do sistema auditivo normal, como a percepção da fala no ruído, mas ainda não há um consenso sobre isso. Objetivo: Estudar o desempenho do sistema auditivo eferente em um grupo de crianças com dificuldade de leitura em comparação às com leitura normal e avaliação de sua relação com a percepção da fala no ruído. Método: Foram selecionadas para o estudo 53 crianças entre oito e 12 anos, das quais 27 tinham dificuldade de leitura e 26 apresentavam leitura normal. A avaliação por emissões otoacústicas evocadas transientes e o teste auditory recognition of words-in-noise foram feitos em todas as crianças. Resultados: A amplitude média da supressão das emissões otoacústicas evocadas transientes mostrou diferença significante entre os dois grupos na orelha direita (p = 0,004) e esquerda (p = 0,028). A avaliação da relação entre a supressão das emissões otoacústicas evocadas transientes e os escores monoaurais do teste auditory recognition of words-in-noise mostrou uma relação negativa moderadamente significante apenas na orelha direita (p = 0,034, r = -0,41) das crianças com leitura normal. Os escores binaurais do auditory recognition of words-in-noise foram significantemente correlacionados com a amplitude de supressão das emissões otoacústicas evocadas transientes na orelha direita (p < 0,001, r = -0,75) e na orelha esquerda (p < 0,001, r = -0,64) das crianças com leitura normal. No grupo com dificuldade de leitura, uma correlação mais fraca foi observada entre os escores binaurais do auditory recognition of words-in-noise e supressão das emissões otoacústicas evocadas transientes, na orelha direita (p = 0,003, r = -0,55) e na esquerda (p = 0,012, r = -0,47). Conclusões: O padrão de supressão das emissões otoacústicas evocadas transientes no grupo com dificuldade de leitura foi diferente em comparação com as crianças com leitura normal e essa diferença pode estar relacionada ao desempenho do sistema eferente. Os escores de palavras no ruído em crianças com dificuldade de leitura foram menores do que nas crianças com leitura normal. Além disso, foi encontrada uma relação entre a supressão das emissões otoacústicas evocadas transientes e os escores de palavras no ruído tanto em crianças com leitura normal quanto nas com dificuldade de leitura.

Intraoperative Motor Evoked Potential Improvement in Cervical Spondylotic Myelopathy: Comparison of Cortical Stimulation Parameters

A Patient Diagnosed with Spinocerebellar Ataxia Type 5 associated with SPTBN2: Case Report / 대한소아신경학회지

Spinocerebellar ataxias (SCAs) are autosomal dominant neurodegenerative disorders which disrupt the afferent and efferent pathways of the cerebellum that cause cerebellar ataxia. Spectrin beta non-erythrocytic 2 (SPTBN2) gene encodes the β-III spectrin protein with high expression in Purkinje cells that is involved in excitatory glutamate signaling through stabilization of the glutamate transporter, and its mutation is known to cause spinocerebellar ataxia type 5. Three years and 5 months old boy with delayed development showed leukodystrophy and cerebellar atrophy in brain magnetic resonance imaging (MRI). Diagnostic exome sequencing revealed that the patient has heterozygous mutation in SPTBN2 (p.Glu1251Gln) which is a causative genetic mutation for spinocerebellar ataxia type 5. With the patient's clinical findings, it seems reasonable to conclude that p.Glu1251Gln mutation of SPTBN2 gene caused spinocerebellar ataxia type 5 in this patient.

The Hyperactivity of Efferent Auditory System in Patients with Schizophrenia: A Transient Evoked Otoacoustic Emissions Study

OBJECTIVE: Electrophysiological studies, which are mostly focused on afferent pathway, have proven that auditory processing deficits exist in patients with schizophrenia. Nevertheless, reports on the suppressive effect of efferent auditory pathway on cochlear outer hair cells among schizophrenia patients are limited. The present, case-control, study examined the contralateral suppression of transient evoked otoacoustic emissions (TEOAEs) in patients with schizophrenia. METHODS: Participants were twenty-three healthy controls and sixteen schizophrenia patients with normal hearing, middle ear and cochlear outer hair cells function. Absolute non-linear and linear TEOAEs were measured in both ears by delivering clicks stimuli at 80 dB SPL and 60 dB SPL respectively. Subsequently, contralateral suppression was determined by subtracting the absolute TEOAEs response obtained at 60 dBpe SPL during the absence and presence of contralateral white noise delivered at 65 dB HL. No attention tasks were conducted during measurements. RESULTS: We found no significant difference in absolute TEOAEs responses at 80 dB SPL, in either diagnosis or ear groups (p>0.05). However, the overall contralateral suppression was significantly larger in schizophrenia patients (p<0.05). Specifically, patients with schizophrenia demonstrated significantly increased right ear contralateral suppression compared to healthy control (p<0.05). CONCLUSION: The present findings suggest increased inhibitory effect of efferent auditory pathway especially on the right cochlear outer hair cells. Further studies to investigate increased suppressive effects are crucial to expand the current understanding of auditory hallucination mechanisms in schizophrenia patients.

Efferent inhibition of otoacoustic emissions in preterm neonates / Inibição eferente das emissões otoacústicas em neonatos prematuros

ABSTRACT INTRODUCTION: Abnormalities in auditory function of newborns may occur not only because of preterm birth, but also from the use of medications and from diseases related to prematurity. OBJECTIVE: To analyze the inhibitory effect from stimulation of the olivocochlear efferent system on transient evoked otoacoustic emissions in preterm neonates, comparing these data with those from full-term neonates. METHODS: This was a prospective, cross-sectional, contemporary cohort study with 125 neonates, pooled into two groups: full-term (72 full-term neonates, 36 females and 36 males, born at 37-41 weeks of gestational age); and preterm (53 neonates, 28 males and 25 females, born at ≤36 weeks of gestational age, evaluated at the corrected gestational age of 37-41 weeks). Otoacoustic emissions were recorded using linear and nonlinear click-evoked stimuli, with and without contralateral stimulation. RESULTS: The inhibitory effect of the efferent pathway in otoacoustic emissions was different (p = 0.012) between groups, and a mean reduction of 1.48 dB SPL in full-term births and of 1.02 dB SPL in preterm births was observed for the non-linear click-evoked stimulus. CONCLUSION: The results suggest a reduced inhibitory effect of the olivocochlear efferent system on otoacoustic emissions in preterm neonates.

RESUMO Introdução: Alterações na função auditiva de recém-nascidos prematuros podem ocorrer não só devido ao nascimento antecipado, mas também pelo uso de medicamentos e por doenças relacionadas à prematuridade. Objetivo: Analisar o efeito inibitório da estimulação do sistema eferente olivo coclear sobre a amplitude das emissões otoacústicas evocadas transientes em recém-nascidos prematuros, comparando esses dados aos de recém-nascidos a termo. Método: Estudo prospectivo, de coorte contemporânea com corte transversal, com 125 recémnascidos, distribuídos em dois grupos: a termo (72 recém-nascidos a termo, 36 feminino e 36 masculino, nascidos entre 37-41 semanas de idade gestacional), e pretermo (53 recém-nascidos, 28 masculino e 25 feminino, nascidos com idade gestacional ≤ 36 semanas avaliados entre 37-41 semanas de idade gestacional corrigida). As emissões otoacústicas foram registradas a partir de estímulos clique lineares e não lineares, com e sem estimulação contralateral. Resultados: O efeito inibitório da via eferente nas otoemissões foi diferente (p = 0,012) entre os grupos, sendo observada uma redução média de 1,48 dB SPL nos nascimentos a termo e 1,02 dBSPL no grupo pretermo para o estímulo clique não-linear. Conclusão: Os resultados sugerem efeito inibitório do sistema eferente olivococlear reduzido sobre as emissões otoacústicas em recém-nascidos prematuros.

Estudio de Estimulación Magnética Transcraneal en pacientes con depresión y trastornos del sueño / Transcranial Magnetic Stimulation in patients suffering from depression and sleep disorders

Introducción: la Estimulación Magnética Transcraneal (EMT) es una técnica neurofsiológica, que permite la inducción de una corriente en el cerebro de forma segura y no invasiva. Está basada en los principios de inducción electromagnética descubiertos por el investigador Michael Faraday hace dos siglos. Recién en 1984, Anthony Barker y su equipo de trabajo desarrollaron un estimulador que permitía despolarizar neuronas en la corteza motora y provocar movimientos contralaterales al activar vías corticoespinales, a partir de lo cual se ha logrado su aplicación en clínica psiquiátrica para diferentes trastornos. La EMTr puede utilizarse como complemento de otros métodos neurocientífcos en el estudio de vías motoras centrales, para el estudio de la excitabilidad cortical y en el mapeo de funciones cerebrales corticales, pudiendo combinar la capacidad de resolución temporal y espacial y la potencialidad de activar o interferir en funciones cerebrales. Materiales y métodos: los pacientes fueron seleccionados de acuerdo al diagnóstico bajo la patología F 33 ­ F 51 por el personal del servicio y remitidos a la unidad de Estimulación Magnética Transcraneal. Se les realizó exámenes complementarios como: TAC de cráneo, electroencefalograma, valoración psicológica pre y post EMTr, dentro de un protocolo estrictamente aplicado, sin el cual no se decide proceder a este tratamiento. Resultados: en el presente estudio no se hizo diferenciaciones entre el tipo de depresión y tampoco en lo relacionado a los trastornos del ritmo del sueño. Se encontró satisfacción en la mayoría de pacientes, sometidos a este tratamiento y muchos mejoraron su depresión y calidad de sueño con la estimulación repetitiva, proponiéndose como una nueva opción de tratamiento no farmacológico ni psicoterapéutico; además es accesible a todo tipo de población, siempre y cuando se cuenta con la infraestructura tecnológica para este procedimiento.

ABSTRACT Introduction: transcranial magnetic stimulation (TMS) is a neurophysiological technique that allows electric currents induction into the brain in a safe and noninvasive way. TMS is based on electromagnetic induction discovered by Faraday two centuries ago. Only in 1984, Anthony Barker and his team developed a stimulator that allowed depolarization of neurons in the motor cortex causing contralateral movements by activating corticospinal pathways, from which it has achieved its application on different conditions in psychiatric clinic. TMS can be used with other neuroscientifc methods to combine the ability of temporal and spatial resolution and the potentiality to activate or interfere brain functions when studying central motor pathways, cortical excitability and brain cortical function mapping. Materials and methods: for the study, patients were selected under pathology F33 and F51, diagnosed by medical service personnel and sent to the Magnetic Stimulation Unit. Additional tests such as head CT, EEG, psychological evaluation pre and post rTMS (repetitive TMS) were performed within a strict protocol. If some of the tests could not be carried out, the treatment did not proceed. Results: in this study, differences on type of depression or sleep rhythm disorders were not made. Our results showed that satisfaction was found in the majority of patients undergoing this treatment and many of them even improved with repetitive stimulation their depression and sleep quality, thus, proposing an alternate non-pharmacological or psychotherapeutic treatment. Besides, it is accessible to most people, as long as the technological infrastructure for this procedure is set up.

Perioperative management of elderly patients undergoing surgery with regional anesthesia

Regional anesthesia can reduce deep vein thrombosis and pulmonary embolism by suppression of the stress responses caused by surgery via the blocking of the afferent and efferent pathways of nerve conduction. It is also effective for control of acute postoperative pain, and compared to general anesthesia, it reduces bleeding during surgery and postoperative respiratory complications. The functional reserves of important organs are reduced in elderly patients although the progression and degree are different from patient to patient. Thus, it is important that safe and appropriate perioperative care including anesthesia be delivered only after a thorough evaluation of the current status of an elderly patient. In this regard, regional anesthesia is worth performing for elderly patients considering its characteristic advantages over general anesthesia. Peripheral nerve blocks using ultrasound are another alternative in elderly patients who might have difficulty undergoing regional or general anesthesia.

Desde la corteza auditiva a la cóclea: progresos en el sistema eferente auditivo / From auditory cortex to cochlea: progress in the auditory efferent system

El sistema eferente auditivo está constituido por el sistema olivococlear y por vías descendentes que provienen de la corteza auditiva y se dirigen a la cóclea. El sistema olivococlear se divide en una porción medial y una lateral, con neuronas que inervan a las células ciliadas externas y a fibras del nervio auditivo respectivamente. El principal neurotransmisor de las sinapsis olivococleares es acetilcolina, y tanto las células ciliadas externas como las fibras del nervio auditivo poseen receptores para esta molécula. El sistema eferente córtico-coclear se origina en la capa V y VI de la corteza auditiva y proyecta a los colículos inferiores y complejo olivar superior, donde a través del sistema olivococlear se conecta con el órgano receptor auditivo. En este artículo se revisan importantes hallazgos obtenidos en los últimos años que involucran (i) nuevos neurotransmisores y receptores del sistema eferente auditivo; (ii) vías descendentes de la corteza auditiva y su rol fisiológico sobre las respuestas cocleares y (iii) rol del sistema eferente auditivo en patologías audiológicas y neuropsiquiátricas.

The auditory efferent system is composed by the olivocochlear fibers and descending projections that originate in the auditory cortex and end in the cochlea. The olivocochlear system is divided into a medial and lateral division, with fibers directed to the outer hair cells and to the auditory nerve fibers respectively. It is known that acetylcholine is the main neurotransmitter of the olivocochlear synapses and that outer hair cells and auditory nerve fibers have receptors to this molecule. The cortico-cochlear efferent system originates in layers V and VI of the auditory cortex. These descending projections are directed to the inferior colliculus and superior olivary complex, a site in which the olivocochlear fibers emerge and connect the brain with the cochlear receptor. In this article recent discoveries obtained in the last years are reviewed: (i) new neurotransmitters and receptors of the olivocochlear system; (ii) anatomy and physiology of descending pathways from the auditory cortex to the cochlea and, (iii) clinical role of auditory efferents in audiological and neuropsychiatric pathologies.

Postural control and central motor pathway involvement in type 2 diabetes mellitus: dynamic posturographic and electrophysiologic studies

Postural instability causes limitations in daily activities of diabetic patients. There is paucity of data regarding central motor pathway involvement in these patients and its relation to postural control. To evaluate postural control and central motor pathway involvement in type 2 diabetic patients. The study included 30 type 2 diabetic patients and 15 healthy, age and sex matched control subjects. Both groups were subjected to physical and full neurological examination, in addition to electrophysiological study including peripheral conduction study and MEPs recorded from the feet muscles. Total neuropathy score was calculated. In addition, dynamic posturographic tests were performed including sensory organization test and MCT. Most of the dynamic posturographic parameters were significantly impaired in diabetic patient group. There were significant abnormalities in most of the parameters of the peripheral conduction study of the patients compared to the controls. According to the Total neuropathy score, 20 patients had peripheral neuropathy. In addition, there was significant prolongation of the left CMCT, decreased left MEP amplitude and increased MEP resting motor threshold on both sides in the patients compared to the control group. Dynamic posturographic parameters showed correlation with most of the parameters of the peripheral conduction study and few of the MEP parameters. Logistic regression analysis showed peripheral neuropathy as the main factor implicated in postural instability in these patients. However, significant correlation was found between MEP amplitude and MCT composite score in patients without peripheral neuropathy. Although type 2 diabetic patients had prolonged CMCT, decreased amplitude and increased resting motor threshold of the MEP response, peripheral neuropathy was the main factor implicated in postural instability. However, the central motor pathway changes documented could be implicated as a possible cause

Effects of etomidate on descending activation of motoneurons in neonatal rat spinal cord in vitro / 生理学报

Descending activation pathways in spinal cord are essential for inducing and modulating autokinesis, but whether the effects of general anesthetic agents on the descending pathways are involved in initiation of skeletal muscle relaxation or not, as well as the underlying mechanisms on excitatory amino acid receptors still remain unclear. In order to explore the mechanisms underlying etomidate's effects on descending activation of spinal cord motoneurons (MNs), the conventional intracellular recording techniques in MNs of spinal cord slices isolated from neonatal rats (7-14 days old) were performed to observe and analyze the actions of etomidate on excitatory postsynaptic potential (EPSP) elicited by electrical stimulation of the ipsilateral ventrolateral funiculus (VLF), which was named VLF-EPSP. Etomidate at 0.3, 3.0 (correspond to clinical concentration) and 30.0 µmol/L were in turn perfused to MN with steadily recorded VLF-EPSPs. At low concentration (0.3 µmol/L), etomidate increased duration, area under curve and/or half-width of VLF-EPSP and N-methyl-D-aspartate (NMDA) receptor-mediated VLF-EPSP component (all P < 0.05), as well as amplitude, area under curve and half-width of non-NMDA receptor-mediated VLF-EPSP component (all P < 0.05), or decreased amplitude and area under curve of VLF-EPSP, its NMDA receptor component, and non-NMDA receptor component (all P < 0.05). However, at 3.0 and 30.0 µmol/L, it was only observed that etomidate exerted inhibitory effects on amplitude and/or duration and/or area under curve of VLF-EPSP (P < 0.05 or P < 0.01) with concentration- and time-dependent properties. Moreover, NMDA receptor-mediated VLF-EPSP component was more sensitive to etomidate at ≥ 3.0 µmol/L than non-NMDA receptor-mediated VLF-EPSP component did. As a conclusion, etomidate, at different concentrations, exerts differential effects on VLF-EPSP and glutamate receptors mediating the synaptic transmission of descending activation of MNs in neonatal rat spinal cord in vitro.

Efecto de supresión eferente de las emisiones otoacústicas transientes y discriminación de habla en ruido / Efferent suppression of transient-evoked otoacoustic emissions and speech discrimination in noise

El tracto olivo-coclear medial ha sido ampliamente estudiado en animales de experimentación y clínicamente en humanos. Se ha sugerido que una de sus funciones se relaciona con la discriminación del habla en presencia de ruido de fondo. Actualmente no se cuenta con estudios sistemáticos de las posibles correlaciones entre el efecto de supresión eferente y el rendimiento en tareas de discriminación de habla en ruido. Por lo anterior, en nuestro laboratorio estamos investigando los valores del efecto de supresión y cómo estos pueden relacionarse con tareas de discriminación del habla. En el presente artículo se reportan los resultados de un estudio piloto en esta materia. Un grupo de 45 sujetos adultos y auditivamente normales fueron estudiados. Los procedimientos incluyeron emisiones otoacústicas transientes, efecto de supresión de las emisiones otoacústicas transientes, reflejos acústicos ipsi y contralaterales (para las frecuencias 0.5, 1, 2 y 4 KHz) y la prueba de HINT. No se encontraron diferencias estadísticamente significativas para el efecto de supresión eferente entre ambos oídos. Por otra parte, no se observaron correlaciones entre la amplitud del efecto de supresión y los valores obtenidos en la prueba de HINT para las subpruebas de habla en ruido. Se discuten los hallazgos encontrados y la necesidad de futuras investigaciones.

The medial olivo-cochlear bundle has been widely studied in experimental animals and clinically, in human subjects. It has been suggested that one of the functions of this bundle relates to the discrimination of speech in the presence of background noise. No systematic studies of possible associations between the efferent suppression of otoacustic emissions (OAEs) and performance on speech-in-noise tasks has been carried out. For this reason, we are investigating the amplitude of the efferent suppression of OAEs and how this may be associated with performance on speech-in-noise tasks. The results of a pilot study on this topic are addressed in this manuscript. A total of 45 normal-hearing adult subjects were studied. Transient-evoked OAEs (TEOAEs), the efferent suppression of TEOAEs, ipsi and contralateral acoustic reflexes (0.5, 1, 2, and 4 HHz) were obtained and the hearing-in-noise-test (HINT) was administered to all the subjects selected. No significant differences were found in the efferent suppression of TEOAEs between ears. No significant correlations between results for the efferent suppression of TEOAEs and those for the HINT were found. These results and the need for further research are discussed.

Associação entre funções da via auditiva eferente e genotoxicidade em adultos jovens / Association between auditory pathway efferent functions and genotoxicity in young adults

Funções da via auditiva eferente incluem a modulação das células ciliadas externas, proteção contra ruído e melhora na detecção da fonte sonora em ambientes ruidosos. Genotoxicidade são danos ao DNA. OBJETIVOS: Analisar associação entre funções da via auditiva eferente com marcadores genotóxicos. Adicionalmente, considerou-se tabagismo e gênero como principais variáveis intervenientes. MATERIAL E MÉTODO: Estudo prospectivo-clínico, quantitativo, transversal, contemporâneo. Foi realizada uma análise da função da via auditiva eferente e indicadores de genotoxicidade em 60 voluntários adultos jovens. RESULTADOS: Idade média dos voluntários foi de 24,86±3,68 anos; 30 do gênero masculino e 30 do gênero feminino, 15 de cada gênero tabagistas e 15 não tabagistas; indivíduos do gênero masculino tabagistas apresentaram maior ocorrência de efeito de supressão das EOAEPDs nas frequências de 2000 e 6000Hz na orelha do lado esquerdo; mulheres tabagistas apresentaram maior prevalência de queixa de dificuldade de ouvir em ambiente ruidoso; indivíduos tabagistas e mulheres apresentaram maiores danos ao DNA; indivíduos com queixas de dificuldade auditiva e zumbido apresentaram maiores índices de genotoxicidade. CONCLUSÕES: Em adultos jovens normo-ouvintes que referem queixas relacionadas às funções da via auditiva eferente, como zumbido e dificuldade auditiva, já é possível observar associação com genotoxicidade considerando interações entre gênero e tabagismo.

Efferent auditory pathways modulate outer hair cells of the cochlea, protect against noise, and improve the detection of sound sources in noisy environments. Genotoxicity is DNA damage. AIM: To study the association between auditory pathway efferent functions with genotoxic markers. The study also considered smoking and gender as two main variables. METHODS: A prospective-clinical, quantitative, cross-sectional, contemporary study. The function of efferent auditory pathways and genotoxicity tests in 60 healthy young subjects were assessed. RESULTS: The mean age of subjects was 24.86 years +/- 3.68 years; there were 30 males and 30 females, 15 of each gender smokers and 15 non-smokers. Male smokers had a higher incidence of DPOEA suppression effect at 2000 and 6000 Hz in the left ear; female smokers had a higher prevalence of complaints of difficulty to hear in noisy environments; smokers and women had a higher mean DNA damage; subjects with complaints of hearing loss and tinnitus had higher genotoxicity. CONCLUSIONS: In young normal-hearing adults that complain about efferent auditory pathways functions, such as tinnitus and hearing impairment, there are possible associations with genotoxicity; interactions between gender and smoking are considered.

Motor Evoked Potentials of the Upper Extremities in Healthy Children

OBJECTIVE: To evaluate and compare the organization of descending motor pathways to upper extremity muscles among healthy children. METHOD: The healthy children were 16 males and 7 females aged 1-19 years (average, 9 years), and eight healthy adults were enrolled as the control group. Transcranial magnetic stimulation was applied to bilateral motor cortices, and motor evoked potentials (MEPs) were recorded using surface electrodes from the first dorsal interossei (FDI), the biceps brachii (BIC), and the deltoid (DEL) muscles. The onset latency, central motor conduction time (CMCT), and amplitude were obtained during a relaxed state. RESULTS: MEPs of FDI were obtained from subjects aged 13 months. The frequency of obtaining MEPs in proximal and distal muscles increased with age, although there was a less frequent incidence of obtaining MEPs in the proximal BIC and DEL muscles compared with those in the distal FDI muscle. MEP amplitudes increased with age, whereas latencies were relatively constant. CMCTs showed a similar pattern of maturation, and adult values were obtained by 13-years-of-age. CONCLUSION: These results suggest that the proximal and distal muscles of the upper extremities show different maturation and organization patterns.

Differential DAergic Control of D1 and D2 Receptor Agonist Over Locomotor Activity and GABA Level in the Striatum

The basal ganglia, a group of nuclei, are associated with a variety of functions, including motor control. The striatum, which is the major input station of the basal ganglia in the brain, is regulated in part by dopaminergic input from the substantia nigra. The striatum is made up 96% of medium spiny neurons which are GABAergic cells. GABAergic cells are known to contain DA receptors which divide into two main branches- the D1 receptor (D1R)-expressing direct pathway and the D2 receptor (D2R)-expressing indirect pathway. The role of these two efferent pathways has not been clear in control of motor behaviors. To establish the influence of the different DA subtypes on GABAergic systems in the striatum, D1 selective receptor agonist (SKF 38393) and D2 selective receptor agonist (Quinpirole) were administered to mice. SKF 38393 and quinpirole were administered intraperitoneally in a volume of 0, 1, 5, 10 (mg/kg) and motor activity was assessed for 60 min immediately after the injection of DA agonists. Mice were sacrificed after behavioral test and the striatum in the brain were dissected for analysis of GABA level with HPLC. Both SKF 38393 and quinpirole dose-dependently increased locomotor activity but, GABA level in the striatum was clearly different in two agonists. These findings provide insight into the selective contributions of the direct and indirect pathways to striatal GABAergic motor behaviors.

Axonal sprouting of somatostatin positive interneurons in the hippocampus in epileptic rats / 中南大学学报(医学版)

OBJECTIVE@#To investigate the axonal sprouting of somatostatin(SS) positive interneurons in temporal lobe epilepsy.@*METHODS@#6-8 week-old healthy male SD rats were divided randomly into an epileptic group (treated by lithium and pilocarpine intraperitoneal injection) and a control group (by lithium and normal sodium intraperitoneal injection). Each group was randomly divided into 5 subgroups at 1,7,15,30, amd 60 d after the injection. Immunohistochemistry method was used to detect the number changes of SS or neuronal nuclei (NeuN) positive neurons in different domains of the hippocampus at different time points in each group, and the coexpression of SS positive interneurons combined with NeuN was detected by double immunofluorescence to observe the dynamic changes and axonal sprouting of SS positive interneurons.@*RESULTS@#The number of SS neurons in the experimental group exceeded that in the control group in the CA1 area at 60 d post-status epileptieus SE (P<0.01), and numerous SS positive fibers were seen throughout the layers of the CAl area at 60 d post-SE. NeuN positive neurons in the stratum oriens and stratum radiatum layers in the initiation site of the CA1 area were beyond normal at 60 d post-SE. The number of double labeled SS interneurons gradually rose at 15 d in stratum oriens of CA1, and even exceeded that of the controls in the stratum oriens and stratum radiatum layers of CA1 at 60 d.@*CONCLUSION@#The numerous SS positive fibers throughout the layers of the CAl area at 60 d post-SE come from the increased interneurons in the stratum oriens and stratum radiatum layers of CA1 area. The pathological axonal sprouting may play an important role in the generation and compensation of temporal lobe epilepsy.

Muerte encefálica: la necesidad de una causa suficiente y necesaria: a propósito de un caso de deseferentación completa por síndrome de Guillain Barré / Brain death: the need for sufficient and necessary cause: apropos of a complete deseferentation case from Guillain Barre syndrome

La muerte encefálica es una causa válida en la certificación del deceso de un paciente, especialmente en condiciones de donación de órganos. Existen escasas situaciones en las que el legislador ha propuesto la realización de exámenes complementarios para su certificación. Presentamos el caso de un paciente con un síndrome de Guillain Barré, que llegó a simular un estado de muerte encefálica, debido al compromiso motor completo, incluyendo musculatura ocular intrínseca. La falta de una condición suficiente y necesaria para declarar la muerte del paciente lleva a la solicitud de exámenes complementarios, en este caso un electroencefalograma, los que determinan la normalidad de la actividad eléctrica cerebral. Se recalca la necesidad de cumplir estrictamente los criterios para determinar la muerte encefálica y el no inhibirse de solicitar exámenes complementarios en condiciones de duda, aún cuando la ley no siempre lo contemple.

Brain death is a valid cause of death certification in a patient, especially in terms of organ donation. There are few situations in which the legislator has proposed further examination for certification. We report the case of a patient with Guillain Barré syndrome, which came to simulate a state of brain death due to motor impairment in full, including intrinsic ocular muscles. The lack of a necessary and sufficient condition for declaring the patient's death led to request additional examinations, in this case an electroencephalogram, which determine the normality of brain electrical activity. It emphasizes the need to comply strictly with the criteria for determining brain death and not to request additional examinations inhibited in a position of doubt, even though the law does not always contemplated.