Mario Estévez

Mario Estévez
The National Institute of Neurology and Neurosurgery, Havana, Cuba · Clinical Neurophysiology

MD MSc PhD. Dr. Sc.

About

256
Publications
63,909
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Introduction
Mario Estévez-Báez BIRTH DATE: October 9 1942 Camagüey, Cuba. CITIZENSHIP: Cuban MAIL ADDRESS: Ave Casablanca 27 entre 19 Oeste y Ave de Guanabacoa, Guiteras, Habana del Este, La Habana, Cuba.. e-Mail marioestevez@infomed.sld.cu MEDICAL GRADUATION: He graduated as MD at the Faculty of Medicine of the Havana University on December 1966. He obtained a PhD in Medical Sciences in July 1980, at the Institute of Experimental Medicine of the Russian Academy of Medical Sciences of the USSR
Additional affiliations
January 2005 - May 2015
Instituto Nacional de Neurología y Neurocirugía
Position
  • Consultor and Member of the Scientific Committee
May 2002 - December 2004
National Institute of Endocrinology
Position
  • Consultor and Senior Researcher
January 2000 - May 2015
National Institute of Neurology and Neurosurgery
Position
  • Senior Researcher and Consultor
Education
September 1977 - July 1980
He graduated as MD at the Faculty of Medicine of the Havana University on December 1966. He became Specialist in the First degree in General Physiology in the year 1972. Later, he graduated as Specialist in Physiology of the Animals and Men in the late Soviet Union in the year 1980. In the year 1981 he graduated as Specialist in the Second Degree in Cuba as “General Physiologist” according to the standard norms established in Cuba, by the Ministry of Public Health. He obtained the higher scientific category in Cuba: “Senior Researcher”, since 1982 year. • He obtained a PhD in Medical Sciences in July 1980, in the Field of Human Clinical Neurophysiology, at the Institute of Experimental Medicine of the Russian Academy of Medical Sciences of the USSR, under the guidance of the actually unfortunately deceased, on year 2009, Professor and Academic of the Soviet Academy of Sciences, Natalya Petrovna Bechtereva, • In the next year (1981) this scientific degree was homologated by the Academy of Sciences of the Republic of Cuba. • In 1995 received the Honorific degree of Master in Military Sciences, in Cuba. • He was elected as a Corresponding Member of the Internatiional Academy of Astronautics (IAA) in 1991, considering his developments in the field of Biology and Medical Astronautics during the time period from 1980 to 1991. Five years later, he was again elected, but now as a Full Member of the IAA. This condition is conferred for life. • Author of three monographs published in Cuba, the late USSR, and in Brazil. • He has had an active participation in Scientific National and International Congresses, Symposiums, and other scientific public activities. • He was the Head of the Scientific Team who developed more than 13 experiments during the Space Flight of the Cuban Cosmonaut General Arnaldo Tamayo Méndez (1981). • As leader in the field of Spatial Medicine and Biology continued his work until 1991, and was the First and Leader author for the development of a special medical equipment (“Cortex II”), designed for the clinical neurophysiologic assessment of cosmonauts and astronauts during short and long-duration spatial flights, that was used for several years later.
Field of study
  • Human Physiology

Publications

Publications (256)
Chapter
Full-text available
The disorders of consciousness (DOC) discussions are actual and permanent subjects for debate in the media and scientific discussion in any forum. Controversies exist in the use of present-day clinical terminology, including terms that may be pejorative in describing patients. The European Task Force on Disorders of Consciousness has proposed a new...
Preprint
Full-text available
Several reports have been published over recent years about Zolpidem's paradoxical arousing effect in unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS) patients. During Zolpidem pharmacological intervention, we emphasized the importance of using the heart rate variability (HRV) methodology to assess the autonomic in a UWS...
Method
Full-text available
Presentamos este Informe de Trabajo como Tributo a la Memoria del Prof. PROFESOR MARIO ESTÉVEZ BÁEZ) En el transcurso de los últimos tres años este colectivo de trabajo ha logrado asimilar y aplicar de manera creadora un conjunto de métodos para el procesamiento digital de señales biológicas de alto significado clínico-fisiológico para las neuroci...
Article
PurposeCardiac autonomic dysfunction in idiopathic Parkinson’s disease (PD) manifests as reduced heart rate variability (HRV). In the present study, we explored the deceleration capacity of heart rate (DC) in patients with idiopathic PD, an advanced HRV marker that has proven clinical utility.Methods Standard and advanced HRV measures derived from...
Article
Full-text available
We read with interest the paper by Chien et al.1 demonstrating that many autistic people present small fiber pathology, which provides structural and physiologic evidence for the involvement of peripheral sensory nerves in autism. The authors remarked that the brain responses to peripheral nociceptive stimulation of autistic people indicated an alt...
Article
Full-text available
Objective: To assess and compare the functional state of the autonomic nervous system in healthy individuals with patients in coma using measures of heart rate variability (HRV), and to evaluate its efficiency in predicting mortality. Methods: Time, informational, and frequency domain HRV indices were calculated from 7 minutes of free of artefacts...
Article
Full-text available
Aim: Identify the main methodological challenges of EEG signal processing with alternative methods. Methods: The nonlinear, non-Gaussian, and non-stationary properties of the brain processes generating the EEG in healthy subjects are a truly controversial topic. For patients with disorders of consciousness these condition cannot obviously be ruled...
Book
Full-text available
La presente obra constituye una compilación de diferentes trabajos que fueron realizados por un grupo de científicos cubanos de diferentes instituciones, que contribuyeron a consolidar criterios acerca de la temática abordada y de los procedimientos metodológicos que debían aplicarse para el procesamiento y análisis de las señales registradas, toma...
Preprint
Considering the properties of the empirical mode decomposition to extract from a signal its natural oscillatory components known as intrinsic mode functions (IMFs), the spectral analysis of these IMFs could provide a novel alternative for the quantitative EEG analysis without a priori establish more or less arbitrary band limits. This approach has...
Preprint
Full-text available
The fast Fourier transform (FFT), has been the main tool for the EEG spectral analysis (SPA). However, as the EEG dynamics shows nonlinear and non-stationary behavior, results using the FFT approach may result meaningless. A novel method has been developed for the analysis of nonlinear and non-stationary signals known as the Hilbert-Huang transform...
Preprint
Full-text available
To the Editor: In a recently published issue of Pediatric Critical Care Medicine, Piantino et al (1) demonstrated that in children with brain injury, lower heart rate variability (HRV) is an early indicator of autonomic system failure, and it predicts progression to brain death. But we propose to consider some methodologic and standardized procedur...
Article
A 15- year- old patient with sickle cell disease with recessive homozygous haemoglobin S/HbSS suffered several crises developmentally after the last of which the patient fell into coma. CT scan then revealed a large infarct of the right cerebral hemisphere. Three weeks after the event, the patient began to demonstrate spontaneous eye opening and sp...
Thesis
Full-text available
Background: The nonlinear, non-Gaussian, and non-stationary properties of the brain processes generating the EEG in healthy subjects are a truly controversial topic. For this reason, the use of traditional methods for the EEG analysis using frequency domain methods based in the Fast Fourier Transform are specially limited when applied to the study...
Article
Full-text available
Purpose Cardiac autonomic dysfunction manifests as reduced heart rate variability (HRV) in idiopathic Parkinson’s disease (PD), but no significant reduction has been found in PD patients who carry the LRRK2 mutation. Novel HRV features have not been investigated in these individuals. We aimed to assess cardiac autonomic modulation through standard...
Article
Full-text available
We compare and discuss three cases including: a clearly brain-dead patient, a vegetative state/unresponsive wakefulness syndrome (VS/UWS) patient and a patient diagnosed as brain-dead (BD) demonstrating some but not all clinical features of a BD state. Two of the patients demonstrated clear presentation allowing for an effective determination of st...
Article
Full-text available
Primary objective: The objective of this study is to assess the functional state of the autonomic nervous system in healthy individuals and in individuals in coma using measures of heart rate variability (HRV) and to evaluate its efficiency in predicting mortality. Design and methods: Retrospective group comparison study of patients in coma clas...
Conference Paper
Full-text available
Objective: To assess and compare the functional state of the autonomic nervous system in healthy individuals with patients in coma using measures of heart rate variability (HRV), and to evaluate its efficiency in predicting mortality. Methods: Time, informational, and frequency domain HRV indices were calculated from 7 minutes of free of artefacts...
Conference Paper
Full-text available
Objective: To assess and compare the functional state of the autonomic nervous system in healthy individuals with patients in coma using measures of heart rate variability (HRV), and to evaluate its efficiency in predicting mortality. Methods: Time, informational, and frequency domain HRV indices were calculated from 7 minutes of free of artefacts...
Presentation
Full-text available
Aim: Identify the main methodological challenges of EEG signal processing with alternative methods. Methods: The nonlinear, non-Gaussian, and non-stationary properties of the brain processes generating the EEG in healthy subjects are a truly controversial topic. For patients with disorders of consciousness these condition cannot obviously be ruled...
Article
Full-text available
The paper assesses the functional state of the autonomic nervous system in healthy individuals and with patients in coma using measures of heart rate variability (HRV), in predicting mortality. Stepwise multiple regression logistic analysis (SMRLA), followed by ROC curve analysis were applied to evaluate predictions. HRV reduction with a progressiv...
Conference Paper
Full-text available
Background: The nonlinear, non-Gaussian, and non-stationary properties of the brain processes generating the EEG in healthy subjects are a truly controversial topic. For patients with disorders of consciousness these condition cannot obviously be ruled out. For this reason the use of traditional methods for the EEG analysis using frequency domain m...
Chapter
Full-text available
The disorders of consciousness (DOC) discussions are actual and permanent subjects for debate in the media and scientific discussion in any forum. Controversies exist in the use of present-day clinical terminology, including terms that may be pejorative in describing patients. Thw European Task Force on Disorders of Consciousness has proposed a new...
Article
Full-text available
Key autonomic functions are in continuous development during adolescence which can be assessed using the heart rate variability (HRV). However, the influence of different demographic and physiological factors on HRV indices has not been fully explored in adolescents. In this study we aimed to assess the effect of age, gender, and heart rate on HRV...
Article
Full-text available
We recently reported a case (case 3 in our article) contributing to the discussion of using ancillary tests in brain death. This case showed brain death clinical features leading to a death certification. We studied the case 9 months later. We found preservation of intracranial structures, with a huge lesion at the brainstem. Conceptually, brain de...
Article
Full-text available
Lewis commented on the results of Machado et al., (2018) studying Jahi’s McMath's brain. Preservation of intracranial structures, both in the brainstem and cerebral hemispheres were documented nine months after a cardiac arrest. Conceptually, a brain-dead patient has a complete absence of intracranial cerebral blood flow. Hence, this contradicts a...
Article
Full-text available
Bernat defended the whole-brain concept of brain death (BD) and the US President's Commission recommended its adoption. Wijdicks stated, “the irreversible absence of functions of the brainstem is the necessary and sufficient component of brain death.” This view fully pertains to brainstem death, and not to the whole brain criterion. The American Ac...
Data
Summary of the calculations related with the adjustment procedure used in this study to cope with the effect of different confounding factors. Abbreviations of HRV indices are the same described in Material and Methods; F(m,n), F-Statistic for m,n respective degrees of freedom; P, associated probability to the corresponding F-Statistic values; K, V...
Data
Summary of the calculations related with the adjustment procedure used in this study to cope with the effect of different confounding factors. Abbreviations of HRV indices are the same described in Material and Methods; F(m,n), F-Statistic for m,n respective degrees of freedom; P, associated probability to the corresponding F-Statistic values; K, V...
Presentation
Full-text available
Objective: To determine the relationship between the anatomic (AC) vs. functional (FC) connectivity, considering short-range and long-range brain networks. Background: In a recent published paper (Machado et al., 2013), we showed that in autistics studied with video without audio tasks vs. video without audio tasks, tended to show lower coherence v...
Presentation
Full-text available
4th International Congress on Minimally Invasive Neurosurgery (ISMINS) April 19-21, 2018, Moscow, Russia Title: Monitoring methods in noninvasive neurosurgery: methodological challenges. Goals: Analysis of some methodological challenges of physiologic monitoring in noninvasive neurosurgery and assessment of alternatives to cope with them. Methods...
Article
Full-text available
Sutton and Clauss presented a detailed review about the effectiveness of zolpidem, discussing recoveries from brain damage due to strokes, trauma and hypoxia. A significant finding has been the unexpected and paradoxical increment of brain activity in vegetative state/unresponsive wakefulness syndrome (VS/UWS). On the contrary, zolpidem is consider...
Article
Full-text available
“The irreversible absence of functions of the brainstem is the necessary and sufficient component of brain death.” This view fully pertains to brainstem death, and not to the whole brain criterion. The American Academy of Neurology summit concluded that ,“Brain death is defined by irreversible loss of consciousness and brainstem function,” accordin...
Article
Full-text available
We compare and discuss three cases including: a clearly brain-dead patient, a vegetative state/unresponsive wakefulness syndrome (VS/UWS) patient and a patient diagnosed as brain-dead (BD) demonstrating some but not all clinical features of a BD state. Two of the patients demonstrated clear presentation allowing for an effective determination of st...
Article
Full-text available
Practice guideline summary: Reducing brain injury following cardiopulmonary resuscitation: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology Calixto Machado, Senior Professor and Researcher of Neurology, Mario Estevez, Cuba; Gerry Leisman, Israel Institute of Neurology and Neur...
Article
Full-text available
Reports in the literature about the very high frequency (VHF) range (0.4-0.9 Hz) of heart rate variability (HRV) are scanty. Its presence in cardiac transplanted patients and other conditions associated to reduced vagal influence to the heart encouraged us to explore this spectral band in healthy subjects and in patients with a definite diagnosis o...
Technical Report
Full-text available
El método de Hilbert-Huang (HH) constituye un novedoso abordaje para el análisis espectral de diferentes señales que puedan estar asociadas con fenómenos no gaussianos, no lineales y no estacionarios, como es el caso del electroencefalograma (EEG). En este trabajo se presentan los fundamentos concretos por los que se considera útil para su apli...
Technical Report
Full-text available
El análisis espectral constituye un método extensamente utilizado para el procesamiento digital de diferentes señales de interés como el EEG, el ECG y la variabilidad de la frecuencia cardiaca. Los procedimientos más utilizados están asociados a los métodos de Fourier, que estrictamente hablando, requieren que los procesos estudiados sean gaussiano...
Technical Report
Full-text available
El método de Hilbert-Huang (HH) constituye un novedoso abordaje para el análisis espectral de diferentes señales de interés como el EEG, el ECG y la variabilidad de la frecuencia cardiaca, que revisten particular interés para la neurología y otras ramas de las neurociencias. Este método fue creado con el objetivo de hacer posible el estudio de fenó...
Technical Report
Full-text available
El método de Hilbert-Huang (HH) constituye un novedoso abordaje para el análisis espectral de diferentes señales que puedan estar asociadas con fenómenos no gaussianos, no lineales y no estacionarios, como es el caso de la variabilidad de la frecuencia cardiaca. En este trabajo se presentan algunos de los principales elementos de carácter metodológ...
Method
Full-text available
Presents a code that is able to use any user-defined resolution to obtain the Hilbert Marginal Spectrum and a smoothed version of the HMS. The code is copyrighted and can be used only for Educational or Academic purposes.
Article
Full-text available
Graf et al. published an interesting review on autism spectrum disorder (ASD), emphasizing the term "autism epidemic," [1] supported by an editorial. [2] Among other factors, increasing ASD diagnoses can be attributed to broader diagnostic criteria and the recognition of ASD existence differentiated from other neurodevelopmental diseases. [2-4] One...
Conference Paper
Cardiac autonomic neuropathy (CAN) is a complication of diabetes with a long asymptomatic phase that is associated with high morbidity and mortality. Early identification of CAN in Type 1 diabetes mellitus (T1DM) may be possible using heart rate variability (HRV). However, the power of HRV analysis to identify CAN depends on the selection of suitab...
Article
Heart rate variability (HRV) analysis is a relevant tool for the diagnosis of cardiovascular autonomic neuropathy (CAN). To our knowledge, no previous investigation on CAN has assessed the complexity of HRV from an ordinal perspective. Therefore, the aim of this work is to explore the potential of permutation entropy (PE) analysis of HRV complexity...
Poster
To evaluate the performance of a combination of heart rate variability complexity features as a prodromal biomarker of spinocerebellar ataxia type 2
Article
Full-text available
The AAN guidelines affirm that brain death (BD) is based on a clinical diagnosis. When clinical examination is hampered, ancillary testing should be used. [1] Greer et al. reported that ancillary tests were mandatory in 6.5% and EEG was listed in 78.8% of US institutions. [2] In several countries, EEG is mandatory for BD diagnosis. [3] Ancillary te...
Article
Full-text available
Introduction: Autistic spectrum disorder (ASD) can be better understood by examining its nature by analyzing brain connectivity. Objective: To better understand the nature of brain connectivities in autistics electrophysiologically. Methods: Brain connectivity can be subdivided into structural or anatomical connectivity (AC) and functional connec...
Article
Full-text available
lntroduction: Autistic spectrum disorder (ASD) can be better understood by examiningits nature by analyzing brainconnectivity. Objective:To better understand the nature of brainconnectivities inautistics electrophysiologically. .Methods:Brain connectivity can be subdivided into structural or anatomical connectivity (AC) and functional connectivi...
Conference Paper
Full-text available
Heartbeat time series are clinically relevant biosignals as they hold substantial information regarding cardiovascular neuroregulatory mechanisms. Disorders of cardiovascular autonomic regulation occur during the pathogenesis of several diseases and are clinically important because of its life threatening consequences. Heart rate variability (HRV)...
Thesis
Full-text available
Antecedentes: El trastorno del espectro autista (TEA) es complejo trastorno del neurodesarrollo que se caracteriza clínicamente por dificultades de la interacción social, alteraciones del lenguaje, variados estereotipos de comportamiento, y déficits cognitivos. Hoy en día muchos autores consideran a TEA como una “epidemia” a nivel mundial. Muchos a...
Chapter
Full-text available
By definition, persistent vegetative state (PVS) cases should be isolated from the outer world. Consequently, one of the most essential challenges in patients with severe brain damage is to assess their residual conscious perception of the environment. Moreover, other key point is to evaluate whether these responses also endow autonomic changes wit...
Conference Paper
Full-text available
The traditional methods used to assess the neurophysiological status of the brain function in patients with disorders of consciousness or brain death, include the electroencephalography (EEG) and the magneto-encephalography (MEG). Also, the study of heart rate variability (HRV) has been used in these patients. The procedures applied for the quantit...
Conference Paper
Full-text available
Introduction: Recently, two papers were published (Chia-Chi et al. 2014) describing a new spectral heart rate variability (HRV) band with limits from 0.4-1.0 Hz, the very high frequency band (VHF). Authors studied the influence of paced respiration and head-up tilt in 15 healthy subjects and concluded that "VHF is as a potential indication of autor...
Article
Full-text available
To develop a method to correct the nonlinear effect of the heart rate (HR) on different heart rate variability (HRV) indices of heart rate variability. The study included 265 healthy participants (17–69 years old), a group of 36 type 1 diabetes mellitus patients, including 15 patients with positive diagnosis of cardiovascular autonomic neuropathy (...
Book
Full-text available
Este libro es el resultado de una acuciosa investigación realizada en la Ataxia Espinocerebelosa tipo 2 (SCA-2); lo que permitió determinar la presencia de neuropatía autonómica cardiovascular (NACv) en enfermos y presintomáticos para la SCA2. La NACv puede ser fácilmente diagnosticada mediante la realización de pruebas sencillas, incruentas y poco...