Miastenia gravis y enfermedad de Alzheimer: una asociación a estudio / Association between myasthenia gravis and Alzheimer’s disease

Introducción La miastenia gravis (MG) y la enfermedad de Alzheimer (EA) son dos de las enfermedades neurológicas en cuya fisiopatología interviene la acetilcolina en distintos niveles. En la primera, la alteración de este neurotransmisor se produce en la unión neuromuscular, y en la segunda, en el sistema nervioso central. Objetivo Analizar la posible relación entre dichas patologías estudiando la prevalencia y la odds ratio de la EA dentro de los pacientes diagnosticados de MG con respecto a la prevalencia de EA en la población general. Pacientes y métodos Se han examinado datos de las historias clínicas electrónicas del sistema de salud de Castilla-La Mancha utilizando el procesamiento de lenguaje natural a través de la plataforma clínica de inteligencia artificial Savana Manager?. Resultados Se ha identificado a 970.503 pacientes mayores de 60 años, de los que 1.028 tenían diagnóstico de MG. La proporción de pacientes con diagnóstico de EA dentro de este grupo (4,28%) es mayor que en el resto de la población (2,82%; p = 0,0047), con una odds ratio de 1,54 (intervalo de confianza al 95%: 1,13-2,08; p = 0,0051), sin que se encuentren diferencias significativas en el análisis bivariante del resto de los factores de riesgo para EA más importantes conocidos hasta ahora. Conclusiones Nuestros resultados sugieren que podría existir un aumento de la prevalencia de EA en pacientes con MG. (AU)

INTRODUCTION Myasthenia gravis (MG) and Alzheimer’s disease (AD) are two of the most important diseases where the dysregulation of acetylcholine activity plays a crucial role. In the first, this dysregulation happens at the level of the neu­romuscular junction and in the second, in the central nervous system (CNS). AIM To analyze the possible relationship between these two pathologies, analyzing the prevalence and the odds ratio of AD within patients previously diagnosed with MG. We will compare these data with respect to the prevalence of AD in the general population. PATIENTS AND METHODS We examined the data obtained by the electronic medical records of patients in the health care system of Castilla La Mancha using the Natural Language Process provided by a clinical platform of artificial intelligence known as the Savana Manager?. RESULTS We identified 970,503 patients over the age of 60 years, of which 1,028 were diagnosed with MG. The proportion of the patients diagnosed with AD within this group (4.28%) was greater than the rest of the population (2.82%) (p = 0,0047) with an odds ratio of 1.54 (confidence interval at 95% 1.13-2.08; p = 0.0051) without finding significant differences in the bivariate analysis for the rest of the most important actual known risk factors for AD. CONCLUSION. Our results suggest that there might be an increase in the prevalence of AD in patients previously diagnosed with MG. (AU)

Triple-seronegative myasthenia gravis: clinical and epidemiological characteristics / Miastenia gravis triplo-soronegativa: características clínicas e epidemiológicas

Abstract Background Myasthenia gravis (MG) is an autoimmune disease usually caused by antibodies against the acetylcholine receptor (AChR-Abs), muscle-specific tyrosine kinase (MuSK-Abs), or low-density lipoprotein receptor-related protein 4 (LRP4-Abs). However, there are MG patients who do not have these antibodies and are thus said to have triple-seronegative (triple-SN) MG. Objective This study aims to describe the frequency and clinical and epidemiological characteristics of patients with triple-SN MG. Methods This was a retrospective cross-sectional study carried out through the analysis of medical records. Descriptive and analytical statistical analysis was performed comparing subgroups of myasthenic patients, classified according to serological profile. Results The sample population consisted of 93 MG patients: 85 were positive for antibodies, 80 (86%) with AChR-Abs, 5 (5.4%) with MuSK-Abs, and no MG patients with LRP4-Abs. Eight patients (8.6%) had triple-SN MG; they had a median age at disease onset of 30 years (21-45). Their most common initial symptoms were ptosis, diplopia, and generalized weakness. Most patients presented with mild symptoms at their last visit, reflecting a median MG composite scale score of 4 (0-6), and 75% of patients had an adequate response to treatment. Conclusion Our study showed a low frequency of triple-SN MG in Brazilian MG patients. Triple-SN MG was predominant in females, who presented with ptosis, diplopia, and generalized weakness, and most patients had an adequate response to immunosuppressive treatment. There was no significant difference between triple-SN MG and the other subgroups.

Resumo Antecedentes A Miastenia gravis (MG) é uma desordem autoimune geralmente causada por anticorpos antirreceptores de acetilcolina (anti-RACh), tirosina quinase músculo-específica (anti-MuSK) ou proteína 4 relacionada ao receptor de lipoproteína de baixa densidade (anti-LRP4). No entanto, em uma parcela dos pacientes, nenhum destes três anticorpos pôde ser detectado, sendo estes casos denominados "triplo-soronegativos". Objetivo Descrever a frequência, bem como as características clínicas e epidemiológicas dos pacientes com MG triplo-soronegativa. Métodos Consiste em um estudo transversal e restrospectivo, realizado através da análise de prontuários médicos. Foi realizada análise estatística descritiva e analítica entre os subgrupos de pacientes, classificados de acordo com o perfil sorológico. Resultados A população consistiu de 93 pacientes com MG: 85 pacientes apresentavam positividade para anticorpos, sendo 80 (86%) com anticorpos anti-RACh, cinco (5,4%) com anti-MuSK, e não foram encontrados pacientes com anti-LRP4. Oito (8,6%) eram pacientes triplo-soronegativos, que apresentaram idade média de início da doença de 30 anos (21-45), e com sintomas iniciais mais comuns de ptose, diplopia e fraqueza generalizada. 75% dos pacientes triplo-soronegativos apresentaram resposta adequada ao tratamento. Conclusão O estudo demonstrou uma baixa frequência da pacientes com MG triplo-soronegativa na população brasileira. A MG triplo-soronegativa foi predominante nas mulheres, que se apresentaram com ptose, diplopia ou fraqueza generalizada, e a maioria dos pacientes apresentou resposta adequada ao tratamento imunossupressor. Não houve diferença significativa entre a MG triplo-soronegativa e os demais subgrupos.

Evaluación de la efectividad de la timectomía como tratamiento de la Miastenia Gravis

Objetivo: evaluar efectividad de timectomía como alternativa de tratamiento a la Miastenia Gravis (MG) en nuestro centro, entre 2007 y 2019, y cómo ha impactado en calidad de vida y manejo farmacológico. Material y Método: cohorte retrospectiva de pacientes sometidas a timectomía por equipo Cirugía Torácica del Hospital Gustavo Fricke (HGF) entre 2007 y 2019. Las variables fueron el tratamiento médico y dosis de anticolinesterásicos pre y post timectomía, y la calidad de vida medida a través de la encuesta MG-QOL15. Se utilizaron medidas de desviación estándar y comparaciones estadísticas para el análisis de estas variables, considerando estadísticamente significativo un p < 0,05. Resultados: total de 20 pacientes, mayoría mujeres jóvenes, timectomía vía transesternal. Dosis de anticolinesterásicos mostró disminución estadísticamente significativa de 5,05 a 3,06 pre y post timectomía respectivamente (p < 0,05). Encuesta MG-QOL15 media de 11,9 puntos. Discusión: Se ha demostrado que la timectomía cumple un rol importante en el manejo de la MG, otorgando una superioridad frente al tratamiento médico exclusivo. La Fundación Americana para Miastenia Gravis, recomienda el uso de la encuesta MG-QOL15 como herramienta para evaluar la calidad de vida. Existe poca literatura nacional en relación a este tema. Conclusión: La timectomía, es un procedimiento que mejora la calidad de vida de los pacientes con MG y permite reducir en forma significativa la dosis de fármacos utilizados.

Objective: To evaluate effectivity of thymectomy as an alternative treatment of MG in our center, between 2007 and 2019 and to know how it has impacted in life quality and pharmacological management. Material and Method: cohort study patients treated with thymectomy by Thoracic Surgical team from Gustavo Fricke Hospital between 2007 and 2019. The study variables were medical treatment and anticholinesterases doses before and after the thymectomy, and life quality measured through MG-QOL15 survey. Standard deviation measures and statistics comparisons were used for the analysis of these variables, considering statistically significant a p < 0.05. Results: total of 20 patients, mainly young women, thymectomy through a Trans-sternal approach. Anticholinesterase doses, showed a statistically significant decrease from 5.05 to 3.06 before and after thymectomy (p < 0.05). Discussion: It has been demonstrated that thymectomy plays an important role on the management of MG, giving a mastery against medical exclusive treatment, The American Foundation for Myasthenia Gravis recommends the use of MG-QOL15 survey as an important tool to evaluate life quality. There is a limited amount of national literature related to this topic. Conclusion: Thymectomy is a life quality changing procedure for MG patients and it helps to significantly reduce the drug doses used.

Electrophysiological evaluation of the neuromuscular junction: a brief review / Avaliação eletrofisiológica da junção neuromuscular: breve revisão

Abstract The nerve terminal and muscle membrane compose the neuromuscular junction. After opening the voltage-gated calcium channels, action potentials from the motor axons provoke a cascade for the acetylcholine release from synaptic vesicles to the synaptic cleft, where it binds to its receptor at the muscle membrane for depolarization. Low amplitude compound muscle action potential typically presents in presynaptic disorders, increasing by more than 100% after a 10-second effort in the Lambert-Eaton myasthenic syndrome and less in botulism. Needle electromyography may show myopathic motor unit action potentials and morphological instability ("jiggle") due to impulse blocking. Low-frequency repetitive nerve stimulation (RNS) is helpful in postsynaptic disorders, such as myasthenia gravis and most congenital myasthenic syndromes, where the number of functioning acetylcholine receptors is reduced. Low-frequency RNS with a decrement >10% is abnormal when comparing the 4th to the first compound muscle action potential amplitude. High-frequency RNS is helpful in presynaptic disorders like Lambert-Eaton myasthenic syndrome, botulism, and some rare congenital myasthenic syndromes. The high-frequency RNS releases more calcium, increasing the acetylcholine with a compound muscle action potential increment. Concentric needle records apparent single-fiber action potentials (spikes). A voluntary activation measures the jitter between spikes from two endplates. An electrical activation measures the jitter of one spike (one endplate). The jitter is the most sensitive test for detecting a neuromuscular junction dysfunction. Most neuromuscular junction disorders are responsive to treatment.

Resumo O nervo terminal e a membrana muscular compõem a junção neuromuscular. Após a abertura dos canais de cálcio dependentes de voltagem, os potenciais de ação do axônio motor provocam uma cascata de eventos que libera acetilcolina das vesículas para a fenda sináptica, ligando-se ao receptor na membrana muscular para despolarização. O potencial de ação muscular composto de baixa amplitude ocorre nas desordens pré-sinápticas, aumentando em mais de 100% após esforço de 10 segundos na síndrome miastênica de Lambert-Eaton e menos no botulismo. A eletromiografia pode mostrar potenciais de ação da unidade motora miopáticos e instabilidade morfológica ("jiggle") devido ao bloqueio do impulso. Estimulação nervosa repetitiva (ENR) de baixa frequência é útil nos distúrbios pós-sinápticos, como miastenia gravis e a maioria das síndromes miastênicas congênitas, quando há número reduzido de receptores de acetilcolina funcionantes. ENR de baixa frequência com decremento >10% é anormal comparando-se à amplitude do quarto com o primeiro potencial de ação muscular composto. ENR de alta frequência é útil nas doenças pré-sinápticas, como síndrome miastênica de Lambert-Eaton, botulismo e algumas síndromes miastênicas congênitas raras. ENR de alta frequência libera mais cálcio, aumenta acetilcolina, resultando em incremento do potencial de ação muscular composto. O eletrodo de agulha concêntrico registra potenciais de ação aparente de fibra única (PAAFU). Ativação voluntária mede jitter entre dois PAAFUs (duas junções neuromusculares). Ativação elétrica mede jitter de um PAAFU (uma junção neuromuscular). Jitter é o teste mais sensível para detectar disfunção de junção neuromuscular. A maioria dos distúrbios juncionais é responsiva ao tratamento.

Timectomía toracoscópica en pacientes con Miastenia Gravis juvenil

Objetivo: Describir la evolución clínica postquirúrgica de una serie de casos de pacientes con Miastenia Gravis juvenil (MGJ) tratados con timectomía por toraoscópica videoasistida (TVA) derecha. Materiales y Métodos: Estudio retrospectivo que incluyó 13 pacientes pediátricos con diagnóstico de MGJ sometidos a timectomía toracoscópica derecha en la Unidad Médica de Alta Especialidad Hospital de Pediatría, Centro Médico Nacional Siglo XXI de México, entre marzo de 2016 y abril de 2022. Los pacientes fueron caracterizados clínicamente y la enfermedad fue clasificada de acuerdo a los criterios de Osserman. La evolución postquirúrgica se evaluó con la clasificación de DeFilippi para determinar la proporción de pacientes con mejoría y la remisión completa. Resultados: Los pacientes incluidos fueron, en su mayoría, mujeres (84,6%) con edad promedio al diagnóstico fue de 11,1 ± 3,1 años. Las cuatro clasificaciones de MG fueron incluidas, con mayor proporción de MG generalizada leve (38,5%), seguida de ocular (23,1%) y generalizada moderada grave (23,1%). La evaluación de la progresión postquirúrgica demostró que a los tres meses de seguimiento 92,3% presentó mejorías, incluyendo la disminución del uso de medicamentos. La remisión total solo se registró en uno de los pacientes. Los pacientes que tuvieron cirugía antes de los 12 meses de evolución de la MGJ presentaron mejores resultados post timectomía por TVA. Conclusión: Se demostró la utilidad de timectomía por TVA en pacientes pediátricos mexicanos con MGJ. Nuestra experiencia agrega evidencia de que los pacientes pediátricos se benefician de la timectomía, mejorando su estado clínico y disminuyendo el uso de medicamentos y complicaciones e la enfermedad.

Objective: To describe the post-surgical clinical evolution of a case series of patients with juvenile myasthenia gravis (JMG) treated with right video-assisted thoracoscopic (TVA) thymectomy. Materials and Methods: Retrospective study that included 13 pediatric patients with JMG who underwent right TVA thymectomy at the Siglo XXI National Medical Center of Mexico between March 2016 and April 2022. Patients were clinically characterized, and the disease was classified according to Osserman's criteria. Post-surgical evolution was evaluated using the DeFilippi classification to determine the proportion of patients with improvement and complete remission. Results: The included patients were mostly women (84.6%) with a mean age at diagnosis of 11.1 ± 3.1 years. The four MG classifications were included, with the highest proportion of mild generalized MG (38.5%), followed by ocular (23.1%) and moderate-severe generalized (23.1%). The evaluation of post-surgical progression showed that after three months of follow-up, 92.3% presented improvements, including a decrease in the use of medications. Complete remission was only recorded in one of the patients. Patients who underwent surgery before 12 months of evolution of JMG had better results after TVA thymectomy. Conclusion: The usefulness of TVA thymectomy in Mexican pediatric patients with JMG was demonstrated. Our experience adds evidence that pediatric patients benefit from thymectomy by improving their clinical status and decreasing the use of medications and complications of the disease.

Tratamento manipulativo osteopático em paciente com síndrome da pessoa rígida e miastenia gravis: relato de caso / Osteopathic manipulative treatment in person with stiff person syndrome and myasthenia gravis: case report

Introdução: Síndrome da Pessoa Rígida (SPR) é uma doença neurológica autoimune rara caracterizada pela rigidez e espasmos musculares episódicos dolorosos, especialmente no tronco e extremidades do corpo, gerando comprometimento funcional importante. Existe uma lacuna de conhecimento sobre os possíveis efeitos do tratamento manipulativo osteopático (TMO) nos sintomas motores de pessoas com SPR. Objetivos: Descrever os efeitos do TMO na tontura, equilíbrio e amplitude de movimento (ADM) cervical em uma pessoa com a SPR e miastenia gravis. Método: Relato de caso baseado no TMO em uma mulher com SPR e miastenia grave. As seguintes avaliações foram utilizadas: Inventário de Brazilian Version of the Dizziness Handicap Inventory (DHI), Fall Efficacy Scale (FES I ­ Brazil), Timed Get Up and Go Test (TUG), Teste de Sentar e Levantar 5 vezes, goniometria dos movimentos da coluna cervical. Resultados: Nenhum resultado expressivo foi obtido pela FES-I (-1,8%) e DHI (0%). Para os testes funcionais (TUG e Sentado para de pé 5 vezes) observamos melhora de 5,8% e 6,7%, respectivamente, após o tratamento. A ADM cervical melhorou substancialmente em todos os movimentos avaliados (flexão: 60%, extensão: 28%, rotação direita: 33%, rotação esquerda:38%, inclinação lateral direita: 77%, inclinação lateral esquerda: 87%). Conclusão: O TMO proposto pareceu ser importante para melhora da ADM cervical no caso relatado. Medo de quedas, impacto da tontura na qualidade de vida e funcionalidade de membros inferiores não demonstrou melhoras após o TMO.

Introduction: Stiff Person Syndrome (SPS) is a rare neurological autoimmune disease characterized by stiffness and painful episodic muscle spasms, especially in the trunk and extremities of the body, causing significant functional impairment in affected individuals. There is a gap in knowledge about the possible effects of an osteopathic manipulative treatment (OMT) on the motor symptoms of people with SPS. Objectives: To describe the effects of an OMT on dizziness, balance deficit, and cervical range of motion (ROM) in a patient with SPS and myasthenia gravis. Methods: This is a case report on an OMT intervention in a woman with SPS and myasthenia gravis. The following assessments were used: Brazilian Version of the Dizziness Handicap Inventory (DHI), Fall Efficacy Scale (FES I ­ Brazil), Timed Get Up and Go Test (TUG), Stand Up Test 5 times, goniometry of cervical movements. Results: No expressive results were obtained for FES I ­ Brazil (-1.8%) and DHI (0%). For the functional tests (TUG and Sit and stand up 5x) we observed an improvement of 5.8% and 6.7%, respectively, after treatment. The cervical ROM improved substantially in all movements tested (flexion: 60%, extension: 28%, right rotation: 33%, left rotation: 38%, right side bending: 77%, left side bending: 87%). Conclusion: The proposed OMT appears to be important for the improvement of cervical ROM in this case. Fear of falls, impact of dizziness on quality of life, and lower limb functionality did not demonstrate meaningful improvements after the OMT.

Miastenia gravis. Actualización diagnóstica y terapéutica / Myasthenia gravis. Update on diagnosis and therapy

La miastenia gravis es una enfermedad autoinmune causada por la presencia de anticuerpos específicos dirigidos a diferentes componentes postsinápticos de la unión neuromuscular, y clínicamente se caracteriza por la presencia de debilidad muscular fatigable. En la etiopatogenia juega un papel central el timo, y los autoanticuerpos patogénicos más frecuentemente detectados están dirigidos al receptor de la acetilcolina. El incremento en el conocimiento de los componentes inmunológicos de la unión neuromuscular en las últimas dos décadas ha sido fundamental para identificar nuevos anticuerpos patogénicos, reducir el porcentaje de pacientes con miastenia seronegativa y proponer una clasificación de los pacientes en subgrupos con interés clínico-terapéutico. Además, en los últimos años hemos asistido al desarrollo de nuevos fármacos destinados al tratamiento de los pacientes con miastenia que muestran refractariedad al tratamiento inmunosupresor convencional (AU)

Myasthenia gravis is an autoimmune disease caused by the presence of specific antibodies targeting different postsynaptic components of the neuromuscular junction, and is clinically characterized by the presence of fatigueable muscle weakness. In the etiopathogenesis plays a central role the thymus and the most frequently detected pathogenic autoantibodies are targeted to the acetylcholine receptor. The increase in the knowledge of the immunological components of the neuromuscular junction in the last two decades has been fundamental to identify new pathogenic antibodies, reduce the percentage of patients with seronegative myasthenia, and propose a classification of patients into subgroups with clinical-therapeutic interest. In addition, in recent years, new drugs have been developed for the treatment of patients with myasthenia gravis that are refractory to conventional immunosuppressive treatment (AU)

El pico flujo espiratorio y la cuenta máxima son marcadores del compromiso respiratorio en la miastenia gravis / Peak expiratory flow and the single-breath counting test as markers of respiratory function in patients with myasthenia gravis

Introducción: La miastenia gravis (MG) es una enfermedad autoinmune mediada por anticuerpos. El cuadro clínico se caracteriza por debilidad muscular fluctuante y fatigable, con frecuente afectación de músculos fonodeglutorios y respiratorios. Dada la severidad que implica el compromiso respiratorio en la MG, su evaluación rutinaria es esencial.Nuestro objetivo fue identificar un marcador semiológico útil en la pesquisa del compromiso respiratorio en pacientes con MG.Métodos: Se realizó un trabajo observacional en pacientes con diagnóstico de MG. Los pacientes fueron evaluados con test de cuenta máxima, pico flujo espiratorio (PEF), cuestionario de disnea modificado (mMRC) y valoración de fuerza del cuello. Los resultados de estos parámetros fueron correlacionados con la medición de CVF (capacidad vital forzada) y presiones bucales estáticas máximas (PiMáx y PeMáx). Resultados:Cuarenta y cinco pacientes con MG fueron incluidos, dos pacientes tenían MGFA grado I, 35 grado II, siete grado III y uno grado IV al momento de la evaluación. Se halló una correlación positiva entre el test de cuenta máxima y la CVF (r = 0,57, p = 0,000), y entre el PEF y la CVF (r = 0,76, p = 0,000). El grado de disnea, según el mMRC, mostró una correlación negativa con la CVF (r =-0,31 p = 0,03). A su vez, el PEF correlacionó con la PeMáx de forma positiva, estadísticamente significativa (r = 0,51, p = 0,002).Conclusiones: El PEF, el test de cuenta máxima y el mMRC fueron útiles para evaluar la función respiratoria en pacientes con MG.(AU)

Introduction: Myasthenia gravis (MG) is an antibody-mediated autoimmune disease characterised by fluctuating, fatigable muscle weakness, frequently involving bulbar and respiratorymuscles. Considering the severity of respiratory involvement in MG, routine evaluation ofrespiratory function is essential.The aim of this study was to identify a useful clinical marker of respiratory involvement inpatients with MG. Methods: We performed an observational study of patients with MG. All cases were evaluatedwith the single-breath counting test, peak expiratory flow (PEF), a modified Medical ResearchCouncil dyspnoea scale (mMRC), and a neck strength assessment. The results of these parameters were correlated with forced vital capacity (FVC), maximal inspiratory pressure (MIP), andmaximal expiratory pressure (MEP). Results: The study included 45 patients with MG: 2 patients classified as grade I on the Myasthenia Gravis Foundation of America classification at the time of evaluation, 35 classified asgrade II, 7 classified as grade III, and one classified as grade IV. Positive correlations were foundbetween single-breath counting test scores and FVC values (r = 0.57, p = .000), and betweenPEF and FVC values (r = 0.76, p = .000). Severity of dyspnoea according to the mMRC scaleshowed a negative correlation with FVC values (r = -0.31, p = .03). PEF also showed a significantcorrelation with MEP (r = 0.51, p = .002). Conclusions: PEF, the single-breath counting test, and the mMRC scale are useful measures forevaluating respiratory function in patients with MG.(AU)

Crisis Miasténica: Reporte de Caso y Revisión de la Literatura / Myasthenic Crisis: Case Report and Literature Review

Introducción. La crisis miasténica es la complicación más grave que sufren los pacientes con Miastenia Gravis. Esta enfermedad se caracteriza clínicamente por debilidad muscular generalizada, que particularmente mejora con el reposo y empeora con el ejercicio debido al agotamiento de la conducción nerviosa a nivel post sináptico. El manejo de la crisis miasténica tiene como piedra angular tratar la causa desencadenante, así como utilizar los fármacos de acción rápida y los descritos en la literatura para enfrentar este escenario, como la plasmaféresis, inmunoglobulinas o terapia biológica. Además, es crucial tener un adecuado manejo desde el punto de vista ventilatorio manteniendo la protección pulmonar y sobre todo diafragmática, con las herramientas disponibles en la actualidad al lado de la cama del paciente. Asimismo, el weaning o destete del ventilador mecánico debe llevarse a cabo de manera objetiva y bajo evaluaciones específicas para lograr un desenlace optimo.

Introduction. Myasthenic crisis is the most serious complication suffered by patients with Myasthenia Gravis. This disease is clinically characterized by generalized muscle weakness, which particularly improves with rest and worsens with exercise due to depletion of nerve conduction at the post-synaptic level. The cornerstone of managing myasthenic crisis is treating the triggering cause, as well as using fast-acting drugs and interventions described in the literature to deal with this scenario, such as plasmapheresis, immunoglobulins, or biological therapy. In addition, it is imperative to ensure adecuate management from the ventilatory perspective, preserving lung function and safeguarding the diaphragm with the tools currently available at the patient's bedside. Likewise, weaning from the mechanical ventilator must be conducted objectively and guided by specific evaluations to achieve an optimal outcome.

[Myasthenia gravis. Update on diagnosis and therapy]. / Miastenia gravis. Actualización diagnóstica y terapéutica.

Myasthenia gravis is an autoimmune disease caused by the presence of specific antibodies targeting different postsynaptic components of the neuromuscular junction, and is clinically characterized by the presence of fatigueable muscle weakness. In the etiopathogenesis plays a central role the thymus and the most frequently detected pathogenic autoantibodies are targeted to the acetylcholine receptor. The increase in the knowledge of the immunological components of the neuromuscular junction in the last two decades has been fundamental to identify new pathogenic antibodies, reduce the percentage of patients with seronegative myasthenia, and propose a classification of patients into subgroups with clinical-therapeutic interest. In addition, in recent years, new drugs have been developed for the treatment of patients with myasthenia gravis that are refractory to conventional immunosuppressive treatment.

Miastenia gravis ocular y factores asociados al desarrollo de una generalización secundaria: descripción de una serie española / Ocular myasthenia gravis and risk factors for developing a secondary generalisation: Description of a Spanish series

Introducción: La miastenia gravis ocular (MGo) es la forma de presentación de la enfermedad más frecuente. Un porcentaje variable de estos pacientes desarrollan una forma generalizada (MGg), siendo los factores de riesgo de conversión y el efecto protector del tratamiento inmunosupresor objeto de controversia en el momento actual. Pacientes y métodos: Diseñamos un estudio monocéntrico retrospectivo, con el objetivo de describir las características demográficas, clínicas y de laboratorio de una cohorte española de MGo, a partir de una serie de MG registrada en el Hospital Universitario de Albacete desde enero del 2008 hasta febrero de 2020. Resultados: Seleccionamos 62 pacientes con MGo de una cohorte de 91 sujetos con MG (68,1%). La mediana de edad al diagnóstico fue de 68 (RIQ 52-75,3), con predominio de MGo de inicio muy tardío (n = 34, 54,8%) y de varones (n = 38, 61,3%). La diplopía binocular fue el síntoma inicial más frecuente (51,7%). La tasa de conversión a MGg fue del 50% (n = 31), con una mediana de tiempo de seis meses (RIQ 2-12,8). Encontramos asociación significativa entre ser mujer (OR: 5,46, IC 95% 1,16-25-74, p = 0,03) y tener AcAchR (OR: 8,86, IC 95% 1,15-68,41, p = 0,04), con el riesgo de desarrollar una MGg. Conclusiones: La tasa de conversión de MGo en nuestra serie es relativamente elevada. La generalización tiene lugar principalmente durante los primeros dos años de evolución y está asociada al sexo femenino y, sobre todo, a la presencia de AcAchR.(AU)

Introduction: Ocular myasthenia gravis (MG) is the most common phenotype of MG at onset. A variable percentage of these patients develop secondary generalisation; the risk factors for conversion and the protective effect of immunosuppressive treatment are currently controversial. Patients and methods: We designed a retrospective single-centre study with the aim of describing the demographic, clinical, and laboratory characteristics of a Spanish cohort of patients with ocular MG from Hospital Universitario de Albacete from January 2008 to February 2020. Results: We selected 62 patients with ocular MG from a cohort of 91 patients with MG (68.1%). Median age at diagnosis was 68 (IQR, 52-75.3), and men accounted for 61.3% of the sample (n = 38). Most patients presented very late-onset ocular MG (n = 34, 54.8%). Binocular diplopia was the most frequent initial symptom (51.7%). The rate of progression to generalised MG was 50% (n = 31), with a median time of 6 months (IQR, 2-12.8). Female sex (OR: 5.46; 95% CI, 1.16-25-74; p = .03) and anti–acetylcholine receptor antibodies (OR: 8.86; 95% CI, 1.15-68.41; p = .04) were significantly associated with the risk of developing generalised MG. Conclusions: The conversion rate observed in our series is relatively high. Generalisation of MG mainly occurs during the first 2 years of progression, and is strongly associated with female sex and especially with the presence of anti–acetylcholine receptor antibodies.(AU)

Descripción de una serie de pacientes con miastenia gravis refractaria / A series of patients with refractory myasthenia gravis

Introducción: Los avances en el tratamiento de la miastenia gravis (MG) han conseguido mejoría en la calidad de vida y el pronóstico de la mayoría de los pacientes. Sin embargo, un 10-20% presenta la denominada MG refractaria sin alcanzar mejoría, con frecuentes recaídas e importante repercusión funcional. Pacientes y métodos: Se seleccionó a pacientes con MG refractaria a partir de una cohorte de pacientes con MG diagnosticados desde enero del 2008 hasta junio del 2019. Se definió MG refractaria como falta de respuesta al tratamiento con prednisona y al menos 2 inmunosupresores o imposibilidad para la retirada del tratamiento sin recaídas en los últimos 12 meses o intolerancia al mismo con graves efectos secundarios. Resultados: Se registraron 84 pacientes con MG, 11 cumplían los criterios de MG refractaria (13%), con una edad media de 47 ± 18 años; un 64% los pacientes con MG refractaria fueron clasificados como miastenia generalizada de comienzo precoz (p < 0,01) con una mayor proporción de mujeres (p < 0,01). La gravedad de la enfermedad al diagnóstico, así como en el momento del análisis de los datos, fue superior en el grupo de MG refractaria con un mayor número de recaídas en el seguimiento. En el modelo de regresión logística se obtuvo una asociación independiente entre MG-R y el número de reagudizaciones graves. Conclusiones: El porcentaje de pacientes con MG refractaria en nuestra serie (13%) es similar al descrito en estudios previos, con frecuencia mujeres con inicio precoz, formas graves de inicio y reiteradas reagudizaciones con ingreso hospitalario en el seguimiento.(AU)

Introduction: Advances in the treatment of myasthenia gravis (MG) have improved quality of life and prognosis for the majority of patients. However, 10%-20% of patients present refractory MG, with frequent relapses and significant functional limitations. Patients and methods: Patients with refractory MG were selected from a cohort of patients diagnosed with MG between January 2008 and June 2019. Refractory MG was defined as lack of response to treatment with prednisone and at least 2 immunosuppressants, inability to withdraw treatment without relapse in the last 12 months, or intolerance to treatment with severe adverse reactions. Results: We identified 84 patients with MG, 11 of whom (13%) met criteria for refractory MG. Mean (standard deviation) age was 47 (18) years; 64% of patients with refractory MG had early-onset generalised myasthenia (as compared to 22% in the group of patients with MG; P<.01), with a higher proportion of women in this group (P<.01). Disease severity at diagnosis and at the time of data analysis was higher among patients with refractory MG, who presented more relapses during follow-up. Logistic regression analysis revealed an independent association between refractory MG and the number of severe relapses. Conclusions: The percentage of patients with refractory MG in our series (13%) is similar to those reported in previous studies; these patients were often women and presented early onset, severe forms of onset, and repeated relapses requiring hospital admission during follow-up.(AU)

Myasthenia gravis in the complex scenario of LRBA-related immune dysregulation / Miastenia gravis no cenário clínico complexo das imunodesregulações relacionadas ao gene LRBA

Autoimmune diseases have been progressively recognized as a potential complication of primary immunodeficiency, especially for some genetic subtypes of common variable immunodeficiency. Although often associated with other autoimmune disorders, autoimmune myasthenia gravis is occasionally identified as a neuromuscular complication of primary immunodeficiency. We report the case of a Brazilian woman with common variable immunodeficiency-8 due to an LRBA variant, in which myasthenia gravis was identified in association with anti-acetylcholine receptor antibody. Marked clinical improvement occurred after intravenous immunoglobulin therapy.

Doenças autoimunes foram progressivamente reconhecidas como complicações potenciais das imunodeficiências primárias, especialmente para alguns subtipos genéticos das imunodeficiências comuns variáveis. Embora se associe comumente a outras doenças autoimunes, a Miastenia gravis autoimune adquirida foi raramente associada como complicação neuromuscular de imunodeficiências primárias. É descrito neste artigo o caso de paciente brasileira do sexo feminino com diagnóstico de Imunodeficiência Comum Variável tipo 8 por variante no gene LRBA, na qual foi identificada Miastenia gravis em associação a anticorpos antirreceptor de acetilcolina. Ela evoluiu com marcante melhora clínica após a introdução de terapêutica com imunoglobulina endovenosa.

Epidemiología de la miastenia gravis en la provincia de Ourense (Galicia, noroeste de España) / Epidemiology of myasthenia gravis in the province of Ourense (Galicia, Spain)

Introducción: La miastenia gravis (MG) es un enfermedad autoinmune que afecta a la transmisión nerviosa a nivel de la unión neuromuscular causando debilidad muscular típicamente fluctuante. Los estudios epidemiológicos constatan un aumento de las tasas de prevalencia de la MG y es especialmente evidente en la población anciana.ObjetivoRealizar un estudio epidemiológico retrospectivo para conocer las tasas de incidencia y prevalencia en la provincia de Ourense (Galicia) caracterizada por el envejecimiento poblacional.Material y métodosLos pacientes fueron reclutados de nuestra base de datos clínica de enfermedades neuromusculares y a través de la búsqueda de pacientes con prescripción activa de bromuro de piridostigmina. La tasa de incidencia se estimó entre los años 2009-2018. Se estableció la fecha de prevalencia al 31/12/2018. El censo de la provincia de Ourense al 1/1/2019 era de 307.651 habitantes, de los que 96.544 (31,4%) tenían una edad ≥ de 65 años.ResultadosSe identificaron 80 casos de MG. La prevalencia fue de 260 casos/1.000.000 habitantes (IC95%: 202,7-316,4), y en la población ≥ 65 años de 517,9/1.000.000 habitantes (IC95%: 363,2-672,9). La incidencia acumulada en el periodo de estudio fue de 15,4 casos/1.000.000 habitantes-año. El inicio precoz (≤ 50 años) ocurrió en el 29,1% de los casos.ConclusiónLa prevalencia de la MG en nuestra área sanitaria es de las más altas entre las cifras previamente reportadas, y es una enfermedad muy prevalente en la población anciana. (AU)

Introduction: Myasthenia gravis (MG) is an autoimmune disease affecting nerve transmission at the level of the neuromuscular junction, and typically causes fluctuating muscle weakness. Epidemiological studies show an increase in MG prevalence, particularly among the older population.ObjectiveWe performed a retrospective epidemiological study to determine the incidence and prevalence of MG in the province of Ourense (Galicia, Spain), characterised by population ageing.Material and methodsPatients were selected from our clinical neuromuscular diseases database by searching for patients with an active prescription for pyridostigmine bromide. Incidence was estimated for the period 2009-2018. We calculated prevalence at 31/12/2018. According to census data for the province of Ourense, the population on 1/1/2019 was 307,651, of whom 96,544 (31.4%) were aged ≥ 65 years.ResultsWe identified 80 cases of MG, with a prevalence rate of 260 cases/1 000 000 population (95% CI, 202.7-316.4), rising to 517.9/1 000 000 population in those aged ≥ 65 (95% CI, 363.2-672.9). Cumulative incidence in the study period was 15.4 cases per 1 000 000 person-years. Early onset (≤ 50 years) was recorded in 29.1% of cases.ConclusionThe prevalence of MG in our health district is one of the highest published figures, and the disease is highly prevalent in the older population. (AU)

Peak expiratory flow and the single-breath count test as markers of respiratory function in patients with myasthenia gravis.

INTRODUCTION: Myasthenia gravis (MG) is an antibody-mediated autoimmune disease characterised by fluctuating, fatigable muscle weakness, frequently involving bulbar and respiratory muscles. Considering the severity of respiratory involvement in MG, routine evaluation of respiratory function is essential. The aim of this study was to identify a useful clinical marker of respiratory involvement in patients with MG. METHODS: We performed an observational study of patients with MG. All cases were evaluated with the single-breath count test, peak expiratory flow (PEF), a modified Medical Research Council dyspnoea scale (mMRC), and a neck strength assessment. The results of these parameters were correlated with forced vital capacity (FVC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP). RESULTS: The study included 45 patients with MG: 2 patients classified as grade I on the Myasthenia Gravis Foundation of America classification at the time of evaluation, 35 classified as grade II, 7 classified as grade III, and one classified as grade IV. Positive correlations were found between single-breath count test scores and FVC values (r = 0.57, P = .000), and between PEF and FVC values (r = 0.76, P = .000). Severity of dyspnoea according to the mMRC scale showed a negative correlation with FVC values (r = -0.31, P = .03). PEF also showed a significant correlation with MEP (r = 0.51, P = .002). CONCLUSIONS: PEF, the single-breath count test, and the mMRC scale are useful measures for evaluating respiratory function in patients with MG.

Epidemiology of myasthenia gravis in the province of Ourense (Galicia, Spain).

INTRODUCTION: Myasthenia gravis (MG) is an autoimmune disease affecting nerve transmission at the level of the neuromuscular junction, and typically causes fluctuating muscle weakness. Epidemiological studies show an increase in MG prevalence, particularly among the older population. OBJECTIVE: We performed a retrospective epidemiological study to determine the incidence and prevalence of MG in the province of Ourense (Galicia, Spain), characterised by population ageing. MATERIAL AND METHODS: Patients were selected from our clinical neuromuscular diseases database by searching for patients with an active prescription for pyridostigmine bromide. Incidence was estimated for the period 2009-2018. We calculated prevalence at 31/12/2018. According to census data for the province of Ourense, the population on 1/1/2019 was 307 651, of whom 96 544 (31.4%) were aged ≥ 65 years. RESULTS: We identified 80 cases of MG, with a prevalence rate of 260 cases/1 000 000 population (95% CI, 202.7-316.4), rising to 517.9/1 000 000 population in those aged ≥ 65 (95% CI, 363.2-672.9). Cumulative incidence in the study period was 15.4 cases per 1 000 000 person-years. Early onset (≤ 50 years) was recorded in 29.1% of cases. CONCLUSION: The prevalence of MG in our health district is one of the highest published figures, and the disease is highly prevalent in the older population.

Ocular myasthenia gravis and risk factors for developing a secondary generalisation: description of a Spanish series.

INTRODUCTION: Ocular myasthenia gravis (MG) is the most common phenotype of MG at onset. A variable percentage of these patients develop secondary generalisation; the risk factors for conversion and the protective effect of immunosuppressive treatment are currently controversial. PATIENTS AND METHODS: We designed a retrospective single-centre study with the aim of describing the demographic, clinical, and laboratory characteristics of a Spanish cohort of patients with ocular MG from Hospital Universitario de Albacete from January 2008 to February 2020. RESULTS: We selected 62 patients with ocular MG from a cohort of 91 patients with MG (68.1%). Median age at diagnosis was 68 (IQR, 52-75.3), and men accounted for 61.3% of the sample (n = 38). Most patients presented very late-onset ocular MG (n = 34, 54.8%). Binocular diplopia was the most frequent initial symptom (51.7%). The rate of progression to generalised MG was 50% (n = 31), with a median time of 6 months (IQR, 2-12.8). Female sex (OR: 5.46; 95% CI, 1.16-25-74; P= .03) and anti-acetylcholine receptor antibodies (OR: 8.86; 95% CI, 1.15-68.41; P = .04) were significantly associated with the risk of developing generalised MG. CONCLUSIONS: The conversion rate observed in our series is relatively high. Generalisation of MG mainly occurs during the first 2 years of progression, and is strongly associated with female sex and especially with the presence of anti-acetylcholine receptor antibodies.

Manifestaciones neurológicas en una paciente con lupus eritematoso sistémico / Neurological manifestations in a patient with systemic lupus erythematosus

El lupus eritematoso sistémico es una enfermedad inflamatoria sistémica cuyo proceso inflamatorio genera un importante número de manifestaciones clínicas articulares y extraarticulares. Entre las manifestaciones extraarticulares destaca la afectación neurológica, y el compromiso puede ser tanto a nivel del sistema nervioso central o periférico. El objetivo de la presente investigación es presentar el caso de una paciente de 56 años de edad, con diagnóstico de lupus eritematoso sistémico de 18 años de evolución quien presentó un cuadro crónico de cefalea, neuropatía periférica y miastenia gravis como manifestaciones neurológicas de la enfermedad. Con el tratamiento de ciclofosfamida y el aumento de la dosis de esteroide, en la actualidad la paciente se encuentra estable. El reporte de este caso hace hincapié en la importancia que revisten las manifestaciones neurológicas como parte de las manifestaciones extraarticulares de esta enfermedad, ya que este tipo de afección es determinante en el curso del lupus eritematoso sistémico y en la calidad de vida de los pacientes(AU)

Systemic lupus erythematosus is a systemic inflammatory disease whose inflammatory process generates a significant number of articular and extra-articular clinical manifestations. Within the extra-articular manifestations, neurological involvement stands out, among others, the commitment can be both at the level of the central or peripheral nervous system. The objective of the present investigation is to present the case of a 56-year-old patient, diagnosed with systemic lupus erythematosus of 18 years of evolution and who has presented chronic symptoms of headache, peripheral neuropathy and myasthenia gravis as neurological manifestations of the illness. The report of this case is considered important to publicize the importance of neurological manifestations as part of the extra-articular manifestations of this disease; this type of condition is decisive in the course of the disease and in the quality of life of patients(AU)

Orbital amyloid tumor associated with myasthenia gravis.

We present a case of a 53-year-old female with an 11 year history of myasthenia gravis (MG) with palpebral ptosis in the left eye which had become more marked over the previous year. Examination revealed a painless left orbital mass causing ptosis. The tumor was surgically removed and histopathology revealed deposits of a hyaline substance which when stained with Congo Red had an apple-green birefringence with polarized light, typical of amyloid. In the absence of amyloid deposits elsewhere in the body, amyloid tumor (AT) was diagnosed. No myelo- or lymphoproliferative syndromes, systemic involvement by amyloidosis or any autoimmune disease were found. The evolution and aesthetic results where satisfactory. Only two cases of orbital AT associated with MG have been described previously; however, in one of the cases, the symptoms of the AT had led to a false diagnosis of MG.