Abstract Introduction: POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) is a monoclonal gammopathy with polyneuropathy as a mandatory criterion. Objective: To describe potential associations between clinical expression and electrodiagnostic patterns in POEMS syndrome. Method: Observational, retrospective, and cross-sectional study of cases cared in a referral center diagnosed with POEMS syndrome from 2009-2019. Results: Eleven cases (8 men) were analyzed. Median age at diagnosis was 40 years (range: 31–51, mean: 37.19 ± 15.67 years). Mean latency at diagnosis was 9.7 ± 8.37 months. In all subjects, initial clinical manifestation was polyneuropathy. Most patients had an axonal pattern (n = 5), followed by demyelinating (n = 4), and mixed (n = 2). Monoclonal gammopathy was observed in all patients (6 λ, and 5 κ cases, immunoglobulin [Ig] G: 72%, IgA: 18%, IgM: 9%). Medical Research Council sum score was lower in the axonal pattern (median: 37.00, vs. 45.5, p = 0.024). There were no differences in the systemic involvement between electrophysiological patterns. Conclusion: Electrophysiological patterns are unlikely to have a clear extra-neurological clinical correspondence; however this will need to be definitively proven with a larger sample size.

Resumen Introducción: El síndrome POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) es una gammapatía monoclonal con polineuropatía como criterio obligatorio. Objetivo: Describir las potenciales asociaciones entre la expresión clínica y los patrones de electrodiagnóstico en el síndrome POEMS. Método: Estudio observacional, retrospectivo y transversal de los casos atendidos en un centro de referencia con diagnóstico de síndrome de POEMS de 2009 a 2019. Resultados: Se analizó a 11 pacientes (8 hombres). La mediana de la edad al diagnóstico fue de 40 años (rango: 31-51, media: 37.19 ± 15.67 años). La latencia media al diagnóstico fue de 9.7 ± 8.37 meses. En todos la manifestación clínica inicial fue la polineuropatía. La mayoría de los pacientes presentaron un patrón axonal (n = 5), seguido del desmielinizante (n = 4) y mixto (n = 2). La gammapatía monoclonal se observó en todos (6 casos l λ 5 κ, inmunoglobulina [Ig] G: 72%, IgA: 18%, IgM: 9%). El Medical Research Council sum score fue menor en el patrón axonal (medianas: 37.00 vs. 45.5, p = 0.024). No se presentaron diferencias en la afección sistémica entre patrones electrofisiológicos. Conclusión: Es poco probable que los patrones electrofisiológicos tengan una correspondencia clínica extraneurológica clara, sin embargo, esto deberá probarse de forma definitiva con un mayor tamaño de muestra.

Abstract Background: The term sural sparing (SS) consists of the early finding in the nerve conduction studies (NCS) of patients with Guillain-Barré syndrome (GBS) of the preservation or normality of the sural nerve with abnormality in sensory nerves of thoracic limbs. Its pathophysiology lies in the greater vulnerability to demyelinating sensory damage in distal segments of the hand than proximally in the calf. The SS is highly specific of acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and is occasionally found in acute motor/sensory axonal neuropathy (AMAN/AMSAN). Objective: We aim to describe the prevalence of SS among the forms of GBS in patients hospitalized in our institute. Materials and methods: We reviewed 61 cases of confirmed GBS (19 demyelinating, 25 axonal, and 17 unclassified forms) corresponding to the 1999-2017 period. Exclusion criteria were as follows: NCS report not available or performed 21 days after the onset of symptoms, chemotherapy in the past 2 years, and/or previous polyneuropathy. SS was defined as the preserved amplitude in sensory action potentials (SAPs) of the sural nerve with abnormal findings in median and/or ulnar nerve SAPs. Results: Thirty patients (21 men, mean 45.5 ± 21.2 years) met the selection criteria, distributed in 12 AIDP, 3 Miller-Fisher syndromes, 9 AMAN, and 6 AMSAN. The NCS was performed 9.1 ± 6.0 days from debut. There were no significant differences in demographic variables or in the amplitude of SAPs between demyelinating and axonal forms. Two patients with AIDP presented SS (16.7%), which was not observed in any other form of GBS. Conclusion: We conclude that, despite the high specificity of SS for AIDP, its low prevalence and the high prevalence of axonal forms in Mexican population suggest that SS is not a suitable electrophysiological screening parameter for differentiating forms of GBS.

Resumen Antecedentes: La preservación sural (PS) es muy específica de la polirradiculoneuropatía desmielinizante inflamatoria aguda (PDIA) y se encuentra de modo ocasional en la neuropatía axonal motora/sensorial aguda (NAM/NASA). Objetivo: Describir la prevalencia de PS entre las formas del síndrome de Guillain-Barré (SGB) en pacientes hospitalizados en la institución de los autores. Material y métodos: Se revisaron 61 casos de SGB confirmados (19 formas desmielinizantes, 25 axonales y 17 no clasificadas) correspondientes al período 1999-2017. Resultados: No se observaron diferencias significativas en las variables demográficas o la amplitud de los potenciales de acción sensorial (PAS) entre las formas desmielinizantes y axo-nales. Dos pacientes con PDIA presentaron PS (16.7%), que no se observó en ninguna otra forma del SGB. Conclusión: A pesar de la alta especificidad de PS para PDIA, su baja prevalencia y la elevada prevalencia de formas axonales en la población mexicana sugieren que la PS no es un parámetro de detección electrofisiológico adecuado para diferenciar las modalidades del SGB.

RESUMO A autora argentina Silvina Ocampo (1903-1993) deixou-nos uma vasta obra que é considerada excelente de várias maneiras. Em 1960, publicou um conto, intitulado “El médico encantador" (O médico encantador), na famosa revista literária Sur. O personagem principal desta obra é um médico de família chamado Albino Morgan que possuía uma verdade secreta: em qualquer casa que ele visitava, também entrava toda a diversidade de doenças. O narrador deste conto -um dos seus pacientes- descreve quatro das doenças de Morgan. Estas condições neurológicas imaginárias permitiu a Ocampo explorar as situações improváveis da vida quotidiana.

ABSTRACT The Argentinian author Silvina Ocampo (1903-1993) left us a vast body of works which are considered outstanding in many ways. In 1960, she published a short story, entitled “El médico encantador" (The Charming Physician), in the renowned literary magazine Sur. The central character of this piece is a family doctor named Albino Morgan, who had a secret truth: in any house he visited, all variety of disease also entered. He brought with him the viruses he disseminated. The narrator of this short story—one of his patients—describes four of Morgan's diseases. These imaginary neurological conditions allowed Ocampo to explore improbable situations in everyday life.

Fundamento:O diabetes afeta aproximadamente 250 milhões de pessoas no mundo. A neuropatia autonômica cardiovascular é uma complicação comum do diabetes que leva à hipotensão postural grave, intolerância ao exercício e aumento na incidência de infarto do miocárdio silencioso.Objetivo:Determinar a variabilidade da frequência cardíaca (FC) e da pressão arterial sistólica (PAS) em pacientes diabéticos com diagnóstico recente.Métodos:O estudo incluiu 30 pacientes com diabetes tipo 2 diagnosticado há menos de 2 anos e 30 controles saudáveis. Nós utilizamos o dispositivo Finapres® para medir durante cinco minutos a FC batimento-a-batimento e a pressão arterial (PA) em três condições experimentais: posição supina, em pé e durante respiração rítmica na frequência de 0,1 Hz. Os resultados foram analisados nos domínios do tempo e da frequência.Resultados:Em relação à FC, foram encontradas diferenças estatisticamente significativas nos valores da análise do domínio do tempo, especificamente em valores determinados a curto prazo, tais como o desvio-padrão dos intervalos NN (DPNN), a raiz quadrada da média das diferenças sucessivas (RQMDS) para a FC e o número de pares de NNs sucessivos que diferem em mais de 50 ms (pNN50). Não houve diferença significativa na análise da PA, mas houve uma dominância simpática nas três condições. A sensibilidade do barorreflexo (SBR) esteve diminuída em pacientes com diabetes de início recente, em comparação aos indivíduos saudáveis durante execução da manobra na posição ortostática.Conclusões:Há uma diminuição na variabilidade da FC em pacientes com diabetes tipo 2 de início recente. Não foram observadas alterações na análise da PA na posição supina, mas a SBR apresentou mudança com a manobra em pé provavelmente causada por hiperatividade simpática.

Background:Diabetes affects approximately 250 million people in the world. Cardiovascular autonomic neuropathy is a common complication of diabetes that leads to severe postural hypotension, exercise intolerance, and increased incidence of silent myocardial infarction.Objective:To determine the variability of heart rate (HR) and systolic blood pressure (SBP) in recently diagnosed diabetic patients.Methods:The study included 30 patients with a diagnosis of type 2 diabetes of less than 2 years and 30 healthy controls. We used a Finapres® device to measure during five minutes beat-to-beat HR and blood pressure in three experimental conditions: supine position, standing position, and rhythmic breathing at 0.1 Hz. The results were analyzed in the time and frequency domains.Results:In the HR analysis, statistically significant differences were found in the time domain, specifically on short-term values such as standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), and number of pairs of successive NNs that differ by more than 50 ms (pNN50). In the BP analysis, there were no significant differences, but there was a sympathetic dominance in all three conditions. The baroreflex sensitivity (BRS) decreased in patients with early diabetes compared with healthy subjects during the standing maneuver.Conclusions:There is a decrease in HR variability in patients with early type 2 diabetes. No changes were observed in the BP analysis in the supine position, but there were changes in BRS with the standing maneuver, probably due to sympathetic hyperactivity.

A variabilidade cardiovascular (VCV) tem sido avaliada em doentes parkinsonianos em vários países e apresenta diferenças étnicas. Objetivo Investigar a variabilidade da frequência cardíaca (VFC) e a variabilidade da pressão arterial (VPA) em doentes parkinsonianos mexicanos. Método Comparamos VFC e VPA entre o grupo de estudo e controles jovens (CJ), a fim de estimar a magnitude da diferença. CVV foi estudada no domínio do tempo e da frequência durante repouso supino (RS), ortostase ativa (OA) e respiração controlada. Estas medições foram comparadas com aquelas de 20 CJ. Resultados Nosso estudo mostrou diminuição em quase todos os parâmetros da VFC em doentes parkinsonianos. A diminuição dos parâmetros da VPA foi encontrada com menos frequência. Conclusão Nossos resultados indicam que a VFC é prejudicada na doença de Parkinson. Alguns parâmetros do VPA também são reduzidos.

Cardiovascular variability (CVV) has been evaluated in patients with Parkinson's disease (PD) in other countries and exhibit ethnic differences. Objective We investigated heart rate variability (HRV) and blood pressure variability (BPV) in Mexican patients with PD. Method We further compared HRV and BPV between this group and young healthy controls (YHC) in order to estimate, for the first time in our country, the magnitude of the difference. Twenty patients were examined. Time- and frequency-domain CVV parameters were studied during supine rest (SR), active standing (AS) and controlled breathing. These measurements were compared to those of 20 YHC. Results In the three conditions tested, our study showed a decrease in almost all HRV parameters in PD patients; on the contrary, decreased BPV parameters were found less frequently and only during SR and AS. Conclusion Our results indicate that HRV is impaired in PD. Some BPV parameters are also diminished.

Apesar da resposta circulatória ao estresse ortostático já foi estudada em pacientes com doença de Parkinson sem hipotensão ortostática típica (PD-TOH), não há uma resposta inicial que é exclusivamente associada com o ortostase ativa (AS). Portanto, buscou-se avaliar esta resposta e compará-la à observada em jovens saudáveis (YHC). Método Em 10 PD-TOH pacientes (8 homens, 60±7 anos, Hoehn e Yahr ≤3) as mudanças na pressão arterial sistólica (PAS) e da frequência cardíaca que ocorrem nos primeiros 30 segundos (seg) de pé foram examinados. Ambos parâmetros foram monitorizados continuamente através do método Peňáz e os critérios de Wesseling. Os pontos de amostragem foram escolhidos com base em estudos anteriores. Estes pontos foram comparados com os de 10 YHC (32±8 anos). Resultados O principal achado deste estudo foi o aumento do tempo entre o início de AS e rebote sistólica no grupo PD-TOH (24±4 vs 19±3 seg, p<0,05). Conclusão Este atraso pode refletir uma latência prolongada na resposta da resistência vascular mediado pelo barorreflexo, mas outros estudos são necessários para confirmar esta hipótese preliminar.

While the circulatory response to orthostatic stress has been already evaluated in Parkinson's disease patients without typical orthostatic hypotension (PD-TOH), there is an initial response to the upright position which is uniquely associated with active standing (AS). We sought to assess this response and to compare it to that seen in young healthy controls (YHC). Method In 10 PD-TOH patients (8 males, 60±7 years, Hoehn and Yahr ≤3) the changes in systolic blood pressure (SBP) and heart rate that occur in the first 30 seconds (sec) of standing were examined. Both parameters were non-invasively and continuously monitored using the volume-clamp method by Peñáz and the Physiocal criteria by Wesseling. The choice of sample points was prompted by the results of previous studies. These sample points were compared to those of 10 YHC (8 males, 32±8 years). Results The main finding of the present investigation was an increased time between the AS onset and SBP overshoot in PD-TOH group (24±4 vs. 19±3 sec; p<0.05). Conclusion This delay might reflect a prolonged latency in the baroreflex-mediated vascular resistance response, but more studies are needed to confirm this preliminary hypothesis.

Poucas descobertas tiveram um impacto tão grande e tamanha relevância para a Medicina clínica como a medição não-invasiva da pressão arterial diastólica. Vários fisiologistas e clínicos talentosos estavam, sem sucesso, em busca de um método não-invasivo para determinar a pressão diastólica. No entanto, a quantificação da pressão arterial diastólica não foi conseguida por qualquer um desses pesquisadores clínicos ou fisiológicos, mas por uma figura improvável e inesperada: Nikolai Sergeevich Korotkoff (1874-1920), um jovem cirurgião do exército russo, trabalhando em condições precárias sob as dificuldades de diversas guerras. É fácil descartar o feito de Korotkoff como uma descoberta fortuita semelhante à de Alexander Fleming na descoberta da penicilina. No entanto, a recente teoria do cisne negro de Nassim N. Taleb pode servir para ilustrar sua descoberta de uma nova e, talvez, surpreendente, forma.

Very few discoveries have had such a large impact on and relevance to clinical medicine as the noninvasive measurement of the diastolic blood pressure. A number of gifted physiologists and clinicians were ineffectively in search of a noninvasive method to determine the diastolic pressure. Nonetheless, the quantification of the diastolic BP was not achieved by any of these clinical or physiological researchers, but by an unlikely and unexpected figure: Nikolai Sergeevich Korotkoff (1874-1920), a young Russian army surgeon, working under precarious conditions in the hardship of diverse wars. It is easy to dismiss the achievement of Korotkoff as a serendipitous discovery, similar to that of Alexander Fleming in the discovery of penicillin. However, Nassim N. Taleb's recent black swan theory may serve to illustrate his discovery in a new and, perhaps, surprising way.

The baroreceptor reflex is poorly known by most physicians even though is fundamental in stabilizing the blood pressure on a beat to beat basis and is crucial for survival. Its fascinating history is briefy reviewed in this article. In 1852 Claude Bernard discovered that the sympathetic nerves of the neck innervate the blood vessels of the skin of the rabbit. Edgar Douglas Adrian in 1932 demonstrated that the sympathetic nerves that innervate the blood vessels discharge spontaneously at a rate of 4-6 per second and thus discovered the physiological basis of the vasomotor tone. In the XIX century Ludwig Traube and Karl Constantine Ewald Hering discovered that blood pressure fluctuates synchronously with respiratory movements and Sigmund Mayer observed that there are also slow non respiratory fluctuations of blood pressure. In 1921 Heinrich Ewald Hering found that high pressure baroreceptors are located in the carotid sinuses and demonstrated that the stimulation of the afferent nerve that innervates it induces bradycardia and hypotension. These studies were further advanced by Corneille Heymans who won the Nobel Prize for these studies in 1938. Later Cowley and Guyton produced sino-aortic denervation in dogs and thereby could demonstrate the fundamental importance of the baroreceptor reflex in the stabilization of blood pressure.

El reflejo barorreceptor es poco conocido por la mayoría de los médicos a pesar de que es fundamental en la estabilización de la presión arterial latido a latido y es crucial para la supervivencia. Su fascinante historia es brevemente revisada en este artículo. En 1852 Claude Bernard descubrió que los nervios simpáticos del cuello inervan los vasos sanguíneos de la piel. En 1932 Edgar Douglas Adrian demostró que los nervios simpáticos que inervan los vasos sanguíneos de la piel descargan en forma espontánea a una frecuencia de cuatro a seis por segundo y de esta forma encontró las bases fisiológicas del tono vasomotor. En el siglo XIX Ludwig Traube y Karl Constantine Ewald Hering descubrieron que la presión arterial fluctúa sincrónicamente con la respiración y Sigmund Mayer observó que también existían oscilaciones más lentas no relacionadas con la respiración. En 1921 Heinrich Ewald Hering mostró la existencia de barorreceptores de alta presión en los senos carotideos y probó que la estimulación de los nervios aferentes que inervan estos receptores induce bradicardia e hipotensión. Estos estudios fueron más tarde avanzados por Corneille Heymans quien ganó el premio Nobel por estos estudios en 1938. En la época de los setentas Cowley y Guyton produjeron denervación sino-aórtica en los perros y de esta manera demostraron la importancia fundamental del reflejo barorreceptor en la estabilización de la presión arterial.

In the XIX century Claude Bernard discovered the action of the nervous system on the peripheral circulation. In the first half of the XX century Ewald Hering discovered the baro-receptor and the reflex control of the heart rate and blood pressure. Cowley and Guyton demonstrated that that sino-aortic denervation induces persistent changes in the blood pressure in the dog. The autonomic nervous system is mainly responsible for the regulation of the circulation and blood pressure in the short term on a beat to beat basis. It controls the vasomotor tone, the heart rate and the cardiac output. With the advent of non invasive methods that measure the blood pressure on a beat to beat basis (Finapres) and with the methods of measurement of the variability of the blood pressure in the frequency domain (spectral analysis) we can currently measure many variables including heart rate, blood pressure, stroke volume, peripheral resistances and the baroreceptor sensitivity and make some inferences about their control mechanisms. These variables can be measured at rest in the supine position, standing up, during rhythmic breathing and during the Valsalva maneuver. In this article we present a review of the neural control of the blood pressure and heart rate.

En el siglo XIX, Claude Bernard descubrió la acción del sistema nervioso sobre el control de la circulación periférica. A principios del siglo XX, Ewald Hering descubrió el barorreceptor arterial y estudió el control reflejo de la frecuencia cardiaca y de la tensión arterial. Cowley y Guyton demostraron que la denervación de los barorreceptores de la carótida y de la aorta produce cambios persistentes en la tensión arterial en el animal experimental. El sistema nervioso autónomo es el principal regulador neural de la circulación y de la tensión arterial a corto plazo y latido a latido y ejerce su función mediante diversos reflejos que regulan el tono vasomotor, la frecuencia cardiaca y el gasto cardiaco. Con los nuevos métodos no invasivos que miden la tensión arterial latido a latido como el Finapres y con los métodos de medición de la variabilidad espectral de la frecuencia cardiaca y la tensión arterial, es posible en la actualidad medir muchas de las variables que regulan la circulación periférica y la tensión arterial. En este trabajo se presenta una revisión del control neural de la tensión arterial y de la frecuencia cardiaca, una breve reseña histórica y datos obtenidos con la medición de la tensión arterial latido a latido de manera no invasiva utilizando el sistema conocido como Finapres.