Transaxonal degenerations of cerebellar connections: the value of anatomical knowledge / Degenerações transaxonais das conexões cerebelares: o valor do conhecimento anatômico

ABSTRACT Transaxonal degenerations result from neuronal death or the interruption of synaptic connections among neuronal structures. These degenerations are not common but may be recognized by conventional magnetic resonance imaging. Objective: The learning objectives of this review include recognition of the imaging characteristics of transaxonal degenerations involving cerebellar connections, the identification of potential encephalic lesions that can lead to these degenerations and correlation of the clinical manifestations with imaging findings that reflect this involvement. Methods: In this report, we review the neuroanatomical knowledge that provides a basis for identifying potential lesions that can result in these degenerations involving cerebellar structures. Results: Hypertrophic olivary degeneration results from an injury that interrupts any of the components of the Guillain-Mollaret triangle. In this work, we describe cases of lesions in the dentate nucleus and central tegmental tract. The crossed cerebellar diaschisis presents specific imaging findings and clinical correlations associated with its acute and chronic phases. The Wallerian degeneration of the middle cerebellar peduncle is illustrated by fiber injury of the pontine cerebellar tracts. A T2-hyperintensity in the dentate nucleus due to a thalamic acute lesion (in ventral lateral nuclei) is also described. Each condition described here is documented by MRI images and is accompanied by teaching points and an anatomical review of the pathways involved. Conclusion: Neurologists and radiologists need to become familiar with the diagnosis of these conditions since their presentations are peculiar and often subtle, and can easily be misdiagnosed as ischemic events, degenerative disease, demyelinating disease or even tumors.

RESUMO Degenerações transaxonais resultam da morte neuronal ou da interrupção de conexões sinápticas entre estruturas neurais. Essas degenerações não são comuns, mas podem ser reconhecidas por imagens de ressonância magnética convencional. Objetivo: Os objetivos de aprendizado desta revisão incluem o reconhecimento das características de imagem de degenerações transaxonais envolvendo conexões cerebelares, a identificação de possíveis lesões encefálicas que podem levar a essas degenerações e a correlação das manifestações clínicas com os achados de imagem que refletem esse envolvimento. Métodos: Neste artigo, revisamos conhecimentos neuroanatômicos que fornecem a base para identificar possíveis lesões que podem resultar nessas degenerações envolvendo estruturas cerebelares. Resultados: A degeneração olivar hipertrófica resulta de uma lesão que interrompe algum dos componentes do triângulo de Guillain-Mollaret. Neste trabalho, descrevemos casos de lesões no núcleo denteado e no trato tegmentar central. A diásquise cerebelar cruzada apresenta achados de imagem específicos e correlações clínicas associadas às suas fases aguda e crônica. A degeneração walleriana dos pedúnculos cerebelares médios é ilustrada pela lesão dos tratos pontino-cerebelares. Uma hiperintensidade em T2 do núcleo denteado devido a uma lesão talâmica aguda (no núcleo ventrolateral) também é descrita. Cada condição aqui descrita é documentada por imagens de ressonância magnética e é acompanhada por pontos didáticos e uma revisão anatômica das vias envolvidas. Conclusão: Neurologistas e radiologistas precisam estar familiarizados com o diagnóstico dessas condições, uma vez que suas apresentações são peculiares e frequentemente sutis, e podem ser facilmente equivocadamente diagnosticadas como lesões isquêmicas, doenças degenerativas, desmielinizantes, ou mesmo tumorais.

Holmes' Tremor Associated with Bilateral Hypertrophic Olivary Degeneration Following Brain Stem Hemorrhage: A Case Report

Holmes' tremor is a condition characterized by a mixture of postural, rest, and action tremors due to midbrain lesions in the vicinity of the red nucleus. Hypertrophic olivary degeneration (HOD) is a rare type of neuronal degeneration involving the dento-rubro-olivary pathway and may present clinically as Holmes tremor. We report on a 59-year-old female patient who developed Holmes tremor in association with bilateral HOD, following brain stem hemorrhage.

Bilateral Hypertrophic Olivary Degeneration in Wilson Disease

Hypertrophic olivary degeneration resulting from lesions of the dento-rubro-olivary pathway, also called Guillain-Mollaret-triangle, has been described previously in a number of cases. Reports about bilateral hypertrophic olivary degeneration of the inferior olivary nuclei are very limited, and the magnetic resonance imaging findings of hypertrophic olivary degeneration in Wilson disease have not yet been described to the best of our knowledge. Herein, we present the first report of bilateral hypertrophic olivary degeneration diagnosed by magnetic resonance imaging in a patient suffering from Wilson disease.

O papel do sistema olivococlear medial em crianças portadoras de TDAH / Role of the medial olivocochlear system among children with ADHD

Crianças portadoras de Transtorno do Déficit de Atenção/Hiperatividade (TDAH) apresentam como um de seus principais sintomas a dificuldade de atenção. Na audição, a Atenção Seletiva que se caracteriza por ser a capacidade de compreender a fala em ambientes ruidosos, pode ser avaliada de várias formas, salientando-se o funcionamento do Sistema Eferente Olivococlear Medial. Este sistema pode ser avaliado pelo exame de emissões otoacústicas (EOA). OBJETIVO: Este trabalho teve por objetivo verificar a ocorrência do efeito de supressão de EOA, caracterizado pela diminuição da amplitude de resposta das emissões otoacústicas evocadas por estímulo transiente (EOAT) em resposta a apresentação de ruído contralateral, em crianças com TDAH (grupo estudo) e normais (grupo controle). Forma de Estudo: Estudo caso-controle. MATERIAL E MÉTODO: Foi realizado um estudo com 20 crianças alocadas em dois grupos de 10 crianças, pareadas por sexo e idade. Foi realizado o exame de EOAET sem e com ruído em ambos os grupos. RESULTADOS: Não houve diferença nas respostas das EOAET sem e com ruído, entre os grupos estudados. CONCLUSÕES: Pôde-se concluir que não há diferenças no funcionamento do Sistema Eferente Olivococlear Medial nas crianças com transtorno do déficit de atenção/hiperatividade em relação às crianças normais.

Attention deficit hyperactivity disorder (ADHD) patients show, as one of the main symptoms, an attentional impairment. Selective attention in the hearing process is the ability to understand speech in a noisy environment, which can be evaluated by several methods. One of the main approaches is the functioning of the Medial Olivocochlear Efferent System, which can be accessed by Transient-Evoked Otoacoustic Emissions (TOAE). OBJECTIVE:This study aimed at evaluating the suppression effect of contralateral noise on TOAE in ADHD (study group) and normal subjects (control group). Study Design: Case-control study. MATERIAL AND METHODS: A study with 20 children distributed in two, age- and gender-matched groups. RESULTS: No differences were found in TOAE responses between the two groups, with and without noise. CONCLUSIONS: We conclude that there were no functional differences in the Medial Olivocochlear Efferent System in the two groups analyzed.

Leber's Hereditary Optic Neuropathy with Olivocerebellar Degeneration due to G11778A and T3394C Mutations in the Mitochondrial DNA

BACKGROUND: Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder with optic nerve atrophy. Although there are no other associated neurological abnormalities in most cases of LHON, cases of "LHON plus" have been reported. CASE REPORT: The proband was a 37-year-old man who had visual and gait disturbances that had first appeared at 10 years of age. He showed horizontal gaze palsy, gaze-evoked nystagmus, dysarthria, and cerebellar ataxia. Brain and orbit MRI disclosed atrophy of the optic nerve and cerebellum, and degenerative changes in the bilateral inferior olivary nucleus. Mutational analyses of mitochondrial DNA identified the coexistence of heteroplasmic G11778A and homoplasmic T3394C mutations. CONCLUSIONS: These results suggest that the combination of G11778A and T3394C mutations leads to an atypical LHON phenotype.

Função do sistema olivococlear medial em crianças com desvio fonológico / Function of the medial olivocochlear system in children with phonological disorders

OBJETIVO: Verificar se crianças com desvio fonológico apresentam alterações do sistema olivococlear medial. MÉTODOS: Trata-se de estudo prospectivo e transversal. Foram avaliadas 19 crianças normo-ouvintes, de ambos os gêneros, com idades entre 4 e 7 anos, que foram divididas em dois grupos: 11 crianças sem desvio fonológico (grupo controle) e oito com desvio fonológico (grupo estudo). A condição auditiva foi verificada por meio da inspeção visual do meato acústico externo, audiometria tonal liminar e imitanciometria. Foram incluídas em ambos os grupos somente as crianças com limiares tonais iguais ou inferiores a 15 dB, timpanometria tipo A e reflexos acústicos presentes. Para avaliar a função do sistema olivococlear medial procedeu-se à avaliação das emissões otoacústicas evocadas transientes (EOAET) com e sem aplicação de ruído branco na intensidade de 60 dBNA contralateralmente. Os dados foram analisados estatisticamente. RESULTADOS: A ocorrência e a média dos valores de supressão das EOAET das orelhas direita e esquerda não apresentaram diferenças nas frequências de 1, 2, 3 e 4 kHz intragrupos estudo e controle. Na comparação da média e ocorrência do efeito supressor das emissões otoacústicas evocadas transientes entre grupo controle e grupo estudo, também não houve diferenças nas frequências analisadas. CONCLUSÃO: Crianças com desvio fonológico não apresentam alterações do sistema olivococlear medial, aspecto evidenciado pela ocorrência do efeito supressor das emissões otoacústicas evocadas transientes.

PURPOSE: To verify whether children with phonological disorders present alterations in the medial olivocochlear system. METHODS: This is a prospective cross-sectional study in which 19 normal hearing children of both genders, with ages between 4 and 7 years, were divided into two groups: 11 children without phonological disorders (control group) and eight with phonological disorders (study group). The auditory condition was verified by visual examination of the external ear canal, pure tone audiometry, and tympanometry. The study included only children with hearing thresholds below or equal to 15 dB, type A tympanometry, and presence of acoustic reflexes. To evaluate the function of the medial olivocochlear system, it was carried out the evaluation of transient evoked otoacoustic emissions (TEOAE) with and without contralateral white noise at 60 dBHL. Data were statistically analyzed. RESULTS: The occurrence and average values of TEOAE suppression in right and left ears did not present differences in the frequencies of 1, 2, 3 and 4 kHz within groups. In the comparison of the mean and the occurrence of the suppressive effect of TEOAE between control and study groups, there was also no difference in the frequencies analyzed. CONCLUSION: Children with phonological disorders do not present alterations in the medial olivocochlear system, as evidenced by the occurrence of the suppressive effect of transient evoked otoacoustic emissions.

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.

Degeneração olivar hipertrófica após ressecção de metástase cerebelar: relato de caso e revisão da literatura / Hypertrophic olivary degeneration secondary to resection of cerebellar metastasis: case report and literature review

Degeneração olivar hipertrófica resulta de lesão no circuito formado pelos núcleos denteado, rubro e olivar inferior (triângulo de Guillain e Mollaret). Pode ser secundária a hemorragias, trauma, neoplasias, entre outras causas que lesem estruturas desse circuito. Destaca-se a relevância deste relato de caso por apresentar um caso de degeneração olivar hipertrófica bilateral, secundária a insulto em ambos os núcleos denteados após ressecção de metástase.

Hypertrophic olivary degeneration represents the results of a lesionthat damages the neuronal connections between the dentate nucleus of the cerebellum, the red nucleus, and the inferior olivary nucleus (Guillain Mollaret triangle). This entity can occur secondary to hemorrhage, trauma, neoplasm and other causes that candamage structures of this pathway. This is an important case report because of its description of a bilateral hypertrophic olivary degeneration, secondary to injuries in both dentate nucleous after metastatic resection.

Projecting from the superior olivary complex to the inner ear in the cat: a retrograde fluorescent labelling study / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate the distribution and projective feature of cat olivocochlear neurons.</p><p><b>METHODS</b>Eleven adult cats were divided into two groups randomly. The experimental group of eight cats was injected of 1% cholera toxin B (CTB) to the left cochlea, while injected of 5% fluoro gold (FG) to the right cochlea. The control group of three cats was injected of saline to bilateral cochlea. After a survival time of 7 days, serial frozen sections were cut in the cat brainstem. All the sections were processed by immunofluorescent procedure for CTB and FG, and the labeled olivocochlear neurons were observed by fluorescent microscope.</p><p><b>RESULTS</b>In the experimental group, the mean total of olivocochlear neurons labeled by CTB and FG was 3210 +/- 168, including lateral olivocochlear neurons (LOC, 2298 +/- 120) and medial olivocochlear neurons (MOC, 913 +/- 64). The labeled neurons were divided into three different types according to their feature of projection: neurons which only projected to the ipsilateral cochlea, neurons which only projected to the contralateral cochlea, and double-labeled neurons which projected both to the ipsilateral and contralateral cochlea, but the double-labeled neurons comprised 3.9% and 15.1% in the LOC and MOC system respectively. No labeled neurons were found in the control group.</p><p><b>CONCLUSIONS</b>There are three types of neurons in the cat olivocochlear system. The neurons which projected to the bilateral cochlea may distribute both in the LOC and MOC system.</p>

Immunoreactivity of Calcium-Binding Proteins in the Central Auditory Nervous System of Aged Rats

OBJECTIVE: While many factors contribute to aging, changes in calcium homeostasis and calcium related neuronal processes are likely to be important. High intracellular calcium is toxic to cells and alterations in calcium homeostasis are associated with changes in calcium-binding proteins, which confine free Ca2+. We therefore assayed the expression of the calcium binding proteins calretinin and calbindin in the central auditory nervous system of rats. METHODS: Using antibodies to calretinin and calbindin, we assayed their expression in the cochlear nucleus, superior olivary nucleus, inferior colliculus, medial geniculate body and auditory cortex of young (4 months old) and aged (24 months old) rats. RESULTS: Calretinin and calbindin staining intensity in neurons of the cochlear nucleus was significantly higher in aged than in young rats (p<0.05) The number and staining intensity of calretinin-positive neurons in the inferior colliculus, and of calbindin-positive neurons in the superior olivary nucleus were greater in aged than in young rats (p<0.05). CONCLUSION: These results suggest that auditory processing is altered during aging, which may be due to increased intracellular Ca2+ concentration, consequently leading to increased immunoreactivity toward calcium-binding proteins.

Distribution of projection neurons of the superior olivary complex in the auditory brainstem in cats / 中南大学学报(医学版)

OBJECTIVE@#To investigate the distribution and morphology of olivocochlear neurons of superior olivary complex in cats.@*METHODS@#Eight adult cats were divided into 2 groups randomly. Cholera toxin B subunit was injected to the left cochlea and fluoro-gold was injected to the right cochlea in the experimental group (n=5). Saline was injected to bilateral cochlea in the control group (n=3). Brainstem tissue was sectioned serially. All of the sections were immunohistochemically treated with ABC and stained with DAB, and then the labelled olivocochlear neurons were observed.@*RESULTS@#The labelled olivocochlear neurons in the experimental group were 2 518 in total. Of them, the number of lateral olivocochlear (LOC) neurons was 1 738 (69.0%), mainly located in the middle of the pons, predominantly projected ipsilaterally. The total of medial olivocochlear (MOC) neurons was 780 (31%), mainly located in dorsomedial periolivary nucleus, medial nucleus of the trapezoid body and ventral nucleus of the trapezoid body, mainly distributed in the rostral extent of the pons, predominantly projected contralaterally.@*CONCLUSION@#In the distribution of olivocochlear neurons in cats, LOC neurons mainly project to the ipsilateral. While the projection of MOC neurons is predominantly contralateral, the distribution of MOC neurons is more adjacent to the rostral extent of the pons than LOC neurons.

Astragalus membranaceus promote expression of insulin-like growth factor 1 in rat model of olivo-cerebellar degeneration / 中国中药杂志

<p><b>OBJECTIVE</b>To observe the effect of Astragalus membranaceus (AM) on insulin-like growth factor 1 (IGF-1) expression in a rat model of olivo-cerebellar degeneration and assess the neuroprotective actions of AM meanwhile.</p><p><b>METHOD</b>Rats model of olivo-cerebellar degeneration was established by using 3-acetylpyridine. The effect of AM on the expression of Calbindin D-28K in inferior olive (IO) neurons by immunohistochemistry, the serum IGF-1 level by Elisa, the IGF-1 mRNA level in the cerebellum by RT-PCR were detected respectively.</p><p><b>RESULT</b>AM effectively improve the serum IGF-1 level, Cerebellar IGF-1 mRNA level and the survival of the 10 neurons in a rat model of olivo-cerebellar degeneration, even at a lower dose (9 g x kg(-1)), and the effect was in a dose-dependent manner.</p><p><b>CONCLUSION</b>AM could effectively upregulate the IGF-1 expression in the rat model of olivo-cerebellar degeneration, and have neuroprotective effect on IO neurons.</p>

Ipsilateral Axial Lateropulsion as an Initial Symptom of Lateral Medullary Infarction: a Case Report

The dorsolateral medullary syndrome (Wallenberg's syndrome) is produced by infarction of a wedge of lateral medulla posterior to the inferior olivary nucleus, and is usually caused by vertebral artery occlusion. Ipsilateral axial lateropulsion as an initial symptom of vertebral artery occlusion is rare, and the responsible anatomical structure is still uncertain. Here we describe a patient presenting with ipsilateral axial lateropulsion as an initial symptom of vertebral artery occlusion.

Percepção auditiva em síndrome de Alport / Auditory perception in Alport's Syndrome

A síndrome de Alport é caracterizada por comprometimentos auditivos, renal, e visual. Objetivo deste estudo é caracterizar as EOAT e a atividade do SOEM (efeito de supressão) em indivíduos com Síndrome de Alport. MATERIAL E MÉTODO: Foram avaliados dez indivíduos com diagnóstico de síndrome de Alport. Foi realizado estudo prospectivo. Foi realizado registro das EOAT na ausência e na presença de estimulação acústica contralateral com a utilização do programa de computador ILO 92 - Otodynamics. RESULTADOS: As amplitudes de resposta das EOAT foram presentes para a resposta global (A) e por faixa de freqüência em 1000, 1500, 2000 e 3000 Hz, em 4 (40 por cento) dos indivíduos e ausentes em 6 (60 por cento) dos indivíduos com perda auditiva. Foram ausentes as respostas na freqüência de 4000 Hz, nas orelhas direita e esquerda. Esses achados são compatíveis com o nível de audição (em dBNA) avaliados. Os indivíduos com resposta global presente em EOAT apresentaram supressão dessa resposta na presença de ruído. CONCLUSÃO: Indivíduos com síndrome de Alport apresentam resultados de EOAT compatíveis com a perda auditiva. Ocorreu o efeito de supressão, sugerindo que a perda auditiva é predominantemente originada por uma disfunção coclear.

Alport's Syndrome is characterized by the presence of renal, hearing and visual disorders. Objective: To characterize the TOAE and the MOES activity (suppression effect) in individuals with Alport's Syndrome. MATERIAL AND METHOD: This is a prospective study of a sample included ten individuals with a diagnosis of Alport's Syndrome. MOES recording was made in the presence and absence of contralateral stimulation (CLS) stimulation using the computer software ILO 92 - Otodynamics. RESULTS: TOAE was present in the global response (A) and in frequency ranges of 1000, 1500, 2000 and 3000 Hz in 4 individuals (40 percent), and absent in 6 individuals (60 percent) with hearing loss. We observed no responses at 4000 Hz in the right and left ears. Individuals that presented global responses to TOAE also suppressed that response when there was noise. CONCLUSION: The suppression effect also occurs with TOAE, suggesting that the hearing loss is predominantly the result of cochlear dysfunction.

Mudanças das emissões otoacústicas por transientes na supressão contralateral em lactentes / Changes in transient evoked otoacoustic emissions contralateral suppression in infants

TEMA: tem sido sugerido que a função do sistema olivo coclear medial (SOCM) pode ser avaliada pelo efeito de supressão das emissões otoacústicas por transientes (EOAT). O ruído competitivo tem um efeito inibitório no funcionamento das células ciliadas externas reduzindo o nível das emissões otoacústicas. Apesar de não haver crescimento pós natal da cóclea, o crescimento da orelha média e o desenvolvimento do processamento auditivo continuam após o nascimento. OBJETIVO: analisar as mudanças no SOCM relacionadas à idade por meio da supressão das EOAT em lactentes saudáveis. MÉTODO: 25 lactentes a termo sem indicadores de risco auditivo foram avaliados em dois momentos: ao nascimento e no sexto mês de vida. Nas duas idades as EOAT foram captadas no modo "Quickscreen", estímulo clique não linear a 78dB peNPS, nas duas orelhas, com e sem ruído contralateral apresentado a 60dB NPS. RESULTADOS: a análise dos dados por meio da ANOVA revelou significante supressão contralateral das EOAT em ambos grupos, porém tanto os níveis das EOAT quanto a magnitude da supressão contralateral das EOAT foram menores no sexto mês de vida quando comparados com a fase neonatal (p<0,01). O efeito de supressão das EOAT no período neonatal foi 2,81dB (± 0,19dB) e no sexto mês de vida foi 1,41dB (± 0,29dB). CONCLUSAO: a magnitude da supressão das EOAT diminuiu do nascimento ao sexto mês de idade. A associação entre a estimulação acústica contralateral e um sistema, disponível comercialmente, rápido na medida das EOAT possibilita o monitoramento não invasivo dos mecanismos eferentes auditivos e parece ser clinicamente promissor na avaliação do estado coclear e do desenvolvimento da função eferente auditiva de lactentes de risco.

Bilateral Hypertrophic Degeneration of the Inferior Olivary Nucleus secondary to Infarction of the Brainstem and Cerebellum: A Case Report

Hypertrophic olivary degeneration (HOD) is regarded as a secondary degenerative change subsequent to the formation of lesions in the "Guillain-Mollaret Triangle," and this is the result of the loss of transsynaptic neurologic input to the inferior olivary nucleus. HOD usually occurs unilaterally, but bilateral hypertrophic olivary degeneration is known to be rare. We experienced one case of this lesion, and we report here on the bilateral HOD that was secondary to infarction of the brainstem and cerebellum.

Bilateral olivary hypertrophy after unilateral cerebellar infarction: case report

Relatamos um caso de hipertrofia olivar bilateral e tremor cerebelar após infarto cerebelar unilateral. A degeneração olivar hipertrófica (DOH) é associada ao aumento de sinal no núcleo olivar inferior (NOI), em sequências pesadas em T2. A DOH tem sido mais frequentemente observada ipsilateralmente a lesões do trato tegmentar central ou contralateralmente a lesões do núcleo denteado ou do pedúnculo cerebelar superior. A inervação bilateral de cada NOI por ambos os núcleos denteados pode ter sido responsável pelas características clínicas e radiológicas neste paciente de 63 anos.

The Effect of Acetylcholine on the Potassium Currents and Length of Outer Hair Cell / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Inner hair cells (IHCs) of the organ of Corti change the external sound stimulus into the electrical signal and transmit this signal to the auditory cortex through afferent nerve fibers. Outer hair cells (OHCs) control the sound transmission function of IHC. OHCs respond with a somatic shape change to alterations in their membrane potential and this electromotile response is believed to provide mechanical feedback to the basilar membrane. Efferent nerve fibers which arise from the superior olivary nucleus in the midbrain and transmit to OHCs through medial olivocochlear bundle use acetylcholine (ACh) as a neurotransmitter. The cholinergic response of OHCs' alpha-9 nicotinic ACh receptor increase the Ca2+ influx, which control OHCs' electromotility by changing a membrane potential. In this research, the effect of ACh on the K+ current in OHC of guinea pig was studied, and the change of OHC length by ACh was studied. MATERIALS AND METHODS: Using the extracted OHC from a guinea pig potassium currents induced by ACh were recorded using the whole-cell patch clamp technique. The change of OHC length when ACh was applied was observed. RESULTS: 1) ACh increases voltage-dependent K+ current in OHC. 2) In the condition, which Ca2+-dependent K+ current is blocked by removing Ca2+ from intra-cellular fluid, ACh has no effect on K+ current in OHC. 3) ACh increases OHC length. CONCLUSION: These experimental results show that ACh from the medial olivocochlear efferent system regulates mobility of OHC, increases the Ca2+-dependent K+ currents in OHC.

A Case of Dystonic Tremor with Left Hemiparesis in Cervicomedullary Infarction

The development of involuntary movement by the lesion in the brainstem and spinal cord has been rarely reported. We report a 56-year-old man who suffered from bilateral dystonic tremor and left hemiparesis by an acute cervicomedullary infarction. The patient had acute infarcted lesion on the anterior-medial cervicomedullary junction located at the inferior olivary nucleus. Current study suggests that the involvement of inferior olivary nucleus in lower medulla could be a cause to develop dystonic tremor by cervicomedullary lesions.