Video head impulse test in bilateral vestibulopathy / Teste do impulso efálico com vídeo (vHIT) na vestibulopatia bilateral

Abstract Introduction: Bilateral vestibulopathy is a rare chronic condition with multiple etiologies. Bilateral vestibulopathy is characterized mainly by unsteadiness when walking or standing, which worsens in darkness, as well as oscillopsia. The degree of handicap caused by bilateral vestibulopathy is variable and remains controversial. Objectives: To determine the value of the video Head Impulse Test in quantifying vestibular deficit and to establish its impact on the quality of life. Methods: Twenty patients (mean age, 41.9 years; range 14-80 years) fulfilling the recent Barany criteria of bilateral vestibulopathy, responded to the Situational Vertigo Questionnaire and underwent vestibular examination including fixation, positional tests, oculomotor test battery and video head impulse test. Results: The relation between each of the video head impulse test parameters and the scores from the questionnaire were statistically analyzed. We observed that patients with covert saccades on the video head impulse test were more likely to have a better quality of life than those with both covert and overt saccades, regardless of the vestibulo-ocular reflex gain in each semicircular canal. The presence of covert saccades was found to be associated with an improved quality of life regardless of the severity of vestibule ocular reflex-deficit. Our conclusion was that vestibule ocular reflex gain, measured by video head impulse test, does not quantify the severity of affection of quality of life in patients with bilateral vestibulopathy. Conclusion: Covert saccades are strategies aiming at minimizing the blurring of vision during head movement, that is an adaptive mechanism that improves quality of life. Therefore, we recommend that video head impulse test should be a part of the routine diagnostic workup of bilateral vestibulopathy.

Resumo Introdução: A vestibulopatia bilateral é uma condição crônica rara, com múltiplas etiologias. É caracterizada principalmente por instabilidade ao caminhar ou ficar de pé, que piora na escuridão, e oscilopsia. O grau de deficiência causado pela vestibulopatia bilateral é variável e permanece controverso. Objetivos: Determinar o valor do teste do impulso cefálico na quantificação do déficit vestibular e estabelecer seu impacto na qualidade de vida. Método: Vinte pacientes (média de 41,9 anos; variação de 14 a 80) que atendiam aos critérios recentes da Bárány Society de vestibulopatia bilateral responderam ao Situational Vertigo Questionnaire e foram submetidos a exame vestibular, inclusive fixação, testes posicionais, bateria de testes oculomotores e teste do impulso cefálico com vídeo. Resultados: A relação entre cada um dos parâmetros do teste do impulso cefálico com vídeo e os escores do questionário foram analisados estatisticamente. Observamos que pacientes com sacadas corretivas cobertas do tipo covert no teste de impulso cefálico com vídeo tinham maior probabilidade de ter melhor qualidade de vida do que aqueles com ambas sacadas corretivas cobertas e sacadas corretivas abertas do tipo overt, independentemente do ganho no reflexo vestíbulo-ocular em cada canal semicircular. Verificou-se que a presença de sacadas corretivas do tipo covert está associada a uma melhor qualidade de vida, independentemente da gravidade do déficit no reflexo vestibulo-ocular. Concluímos que o ganho no reflexo vestíbulo-ocular, medido pelo teste do impulso cefálico com vídeo, não quantifica a gravidade do comprometimento da qualidade de vida em pacientes com vestibulopatia bilateral. Conclusão: As sacadas corretivas do tipo covert são estratégias que visam minimizar o embaçamento da visão durante o movimento da cabeça, ou seja, um mecanismo adaptativo que melhora a qualidade de vida. Portanto, recomendamos que o teste do impulso cefálico com vídeo faça parte da rotina de diagnóstico da vestibulopatia bilateral.

Profile and neuropsychological differences in adolescent students with and without dyslexia / Perfil y diferencias neuropsicológicas en alumnos adolescentes con y sin dislexia

Abstract Dyslexia is a problem of increasing prevalence in school-age students. The latest experiences in the application of neuropsychology to education are interesting because they allow for the evaluation of different neuropsychological variables to obtain a better understanding of the learning processes of students in this population for specific subsequent interventions. The purpose of this study was to explore the following neuropsychological variables related to reading in adolescent students with and without dyslexia. The sample consisted of 60 students between 13 and 15 years of age, 30 with dyslexia and 30 without. The King Devick test was used to assess the saccadic eye movements, specifically the fast and automated denomination of digits; the Harris laterality test was used to evaluate functional laterality, and the ENFEN test for executive functions. The results revealed significant differences between the two groups. Students with dyslexia scored lower on the three neuropsychological skills assessed. These findings suggest that students with dyslexia may manifest poorer performance in those neuropsychological skills that are key to reader development.

Resumen La dislexia es un problema que cada vez afecta más al alumnado en edad escolar. Las últimas experiencias de aplicación de la neuropsicología al ámbito educativo resultan interesantes porque van a permitir evaluar distintas variables neuropsicológicas con el objeto de comprender mejor los procesos de aprendizaje del alumnado para plantear posteriormente intervenciones específicas en esta población. El propósito de este estudio fue explorar variables neuropsicológicas relacionadas con la lectura y escritura en estudiantes con y sin dislexia. La muestra estuvo compuesta por 60 estudiantes de entre 13 y 15 años, 30 con dislexia y treinta sin dislexia. La prueba King Devick fue utilizada para valorar los movimientos oculares sacádicos, la prueba de la lateralidad de Harris para evaluar la lateralidad y la prueba ENFEN para las funciones ejecutivas. Los resultados revelaron diferencias significativas entre los dos grupos. Los estudiantes con dislexia obtuvieron puntuaciones más bajas en las tres habilidades neuropsicológicas evaluadas. Estos hallazgos sugieren que los niños con dislexia podrían manifestar un peor desempeño en habilidades neuropsicológicas que son clave para el desarrollo lector y escritor.

The neural mechanisms of voluntary control of saccadic eye movements / 中华行为医学与脑科学杂志

Voluntary control of saccadic eye movements is a kind of saccades controlled by conscious and always used to investigate the brain areas related to saccades and ability of response inhibition and work memory.Researching the neural mechanisms of voluntary control of saccadic eye movements could provide a basis to study the advanced cognitive function of brain and facilitate to explore basic neural mechanisms of abnormal saccadic in brain disorders.As neuroimaging technologies develops,intensive studies about the neural mechanisms of voluntary control of saccadic eye movements have been made great progress.It is showed that several brain areas such as prefrontal cortex,subcortical areas and parietal cortex mainly in participate.These multiple brain regions are involved in voluntary control of saccadic eye movements at different stages.Antisaccades and memory-guided saccades including different brain regions because of their different characteristics of saccadic.The future direction of the research is to combine study with neural imaging technology,and to study more about the brain regions and their functional connectivity involved in voluntary control of saccadic eye movements.

Saccadic eye movements in Parkinson's disease.

This review focuses on saccadic eye movement research in Parkinson’s disease (PD) patients. Results from various studies related to Parkinson disease and saccades have been discussed in terms of various saccadic parameters like latency, amplitude, velocity and gain. Neural circuitry of saccadic eye movements and cognitive processes and it’s relation with altered saccadic performance in Parkinson disease has been discussed here. This article also covers various research paradigms commonly used to study saccades. Eff ects of medication on saccadic parameters in PD patients have also been discussed along with the eff ects of deep brain stimulation of subthalamic nucleus on saccadic performance in PD patients. Literature review was done using online Pubmed search engine and National Medical Library.

Síndrome de opsoclonus-mioclonus / Opsoclonus-myoclonus syndrome

El síndrome opsoclonus- mioclonus es una rara entidad, que en niños se caracteriza por: irritabilidad, movimientos oculares caóticos con componentes verticales, horizontales, rotatorios (opsoclonus), mioclonus y ataxia. Se asocia en un alto porcentaje de casos con neuroblastoma aunque otras etiologías son también reconocidas (infecciosa-parainfecciosa, tóxicos). Un mecanismo autoinmune se considera responsable de la disfunción de estructuras en el tronco cerebral y cerebelo, que explicarían algunos de los síntomas cardinales (opsoclonus-mioclonus, ataxia). Sin embargo los signos de compromiso encefalopáticos y el elevado porcentaje de pacientes con secuelas neurocognitivas y psiquiátricas hablarían a favor de una disfunción más amplia. El tratamiento con esteroides, ACTH y drogas inmunomoduladoras e inmunosupresoras es actualmente utilizado, sin embargo es necesario realizar estudios prospectivos con protocolos terapéuticos uniformes para definir si el uso prolongado de estas drogas influencian favorablemente la evolución en este grupo de pacientes.

The opsoclonus-myoclonus syndrome in children is a rare entity which is characterized by irritability, chaotic ocular movements with vertical, horizontal, rotatory components (opsoclonus) along with myoclonus and ataxia. In a high proportion of cases, it is associated with neuroblastoma although other etiologies involving infectious or toxic agents have been reported. An autoimmune mechanism would be responsible for the dysfunction of structures in brain stem and cerebellum thus explaining some of the cardinal symptoms such as opsoclonus, myoclonus and ataxia. However, encephalopathic symptoms and the high percentage of patients with neurocognitive and psychiatric sequels are in favor of a wider dysfunction. Treatment with steroids, ACTH, immunomodulatory or immunosuppressive drugs is being used although prospective studies are needed to determine whether the prolonged use of these drugs influences favorably the evolution of these patients.

Asociación entre la alteración de los movimientos oculares sacádicos y la esquizofrenia: un estudio de casos y controles / Altered Saccadic Eye Movements in Schizophrenia: A Case-Control Study

Contexto: Los pacientes con diagnóstico de esquizofrenia presentan alteraciones en los movimientos oculares, principalmente en los movimientos sacádicos; ésto se plantea como un marcador biológico de la enfermedad. Objetivo: Evaluar la alteración de los movimientos oculares sacádicos como marcadores biológicos en sujetos con diagnóstico de esquizofrenia. Metodología: Estudio de casos y controles en 50 pacientes con diagnóstico de esquizofrenia y 48 controles sanos emparejados por edad y sexo. Se diseñó un instrumento electrónico y un software para realizar la prueba electrooculográfi ca y analizar las señales mediante algoritmos computacionales. A cada participante se le realizó una entrevista psiquiátrica estructurada, un electrooculograma y una evaluación optométrica. Se caracterizó la señal electrooculográfi ca, identifi cando las regiones donde ocurrían las sacadas o saltos. De estas regiones se obtuvieron valores para los parámetros: amplitud, duración, ganancia, latencia y velocidad pico. Se hizo un análisis estadístico de variación con el método ANOVA de una vía o con el método no parámetrico de Kruskal-Wallis, cuando los datos no tenían distribución normal. Resultados: Se observaron diferencias estadísticamente signifi cativas entre ambos grupos únicamente para el parámetro “latencia” en amplitudes visuales mayores de 45 grados y en la realización del movimiento antisacádico para amplitudes visuales de 10 y 20 grados, patrones reportados por otros investigadores.

Context: Altered saccadic eye movements are considered biological markers of schizophrenia. Objective: To evaluate alterations of saccadic eye movements as biological markers in subjects diagnosed with schizophrenia. Methodology: Case-Control study in 50 patients diagnosed with schizophrenia and 48 healthy control subjects paired by age and gender. An electronic device and software were designed to perform the electro-oculographic test and to analyze the signals using computational algorithms. A structured psychiatric interview, an electro-oculogram and an optometric test were performed on all the participants. The electro-oculographic signal was then characterized, identifying the regions where the saccadic leaps occurred. Within these regions the parameters amplitude, duration, gain, latency and peak velocity were measured. A statistical analysis was performed using the one way ANOVA or the Kruskall-Wallis when the data did not have a normal distribution. Results: Statistically signifi cant differences were observed between both groups only for the “latency” in visual amplitudes larger than 45 degrees and in the anti-saccadic movement in visual amplitudes between 10 and 20 degrees, patterns that have been reported by other researchers.