Factors Predicting Prolonged Mechanical Ventilation in Guillain-Barré Syndrome.

BACKGROUND: Up to 30% of patients with Guillain-Barré syndrome require mechanical ventilation and 5% die due to acute complications of mechanical ventilation. There is a considerable group of patients that will need prolonged mechanical ventilation (considered as >14 days) and should be considered for early tracheostomy. The objective of this study is to identify risk factors for prolonged mechanical ventilation. METHODS: We prospectively analyzed patients with Guillain-Barré diagnosis with versus without prolonged mechanical ventilation. We considered clinical and electrophysiological characteristics and analyzed factors associated with prolonged mechanical ventilation. RESULTS: Three hundred and three patients were included; 29% required mechanical ventilation. When comparing the groups, patients with prolonged invasive mechanical ventilation (IMV) have a lower score on the Medical Research Council score (19.5 ± 16.2 vs 27.4 ± 17.5, p = 0.03) and a higher frequency of dysautonomia (42.3% vs 19.4%, p = 0.037), as well as lower amplitudes of the distal compound muscle action potential (CMAP) of the median nerve [0.37 (RIQ 0.07-2.25) vs. 3.9 (RIQ1.2-6.4), p = <0.001] and ulnar nerve [0.37 (RIQ0.0-3.72) vs 1.5 (RIQ0.3-6.6), p = <0.001], and higher frequency of severe axonal damage in these nerves (distal CMAP ≤ 1.0 mV). Through binary logistic regression, severe axonal degeneration of the median nerve is an independent risk factor for prolonged IMV OR 4.9 (95%CI 1.1-21.5) p = 0.03, AUC of 0.774, (95%CI 0.66-0.88), p = < 0.001. CONCLUSIONS: Severe median nerve damage is an independent risk factor for prolonged mechanical ventilation.

Examining the Features of Neuroleptic Malignant Syndrome in Anti-NMDA Receptor Encephalitis: A Case-Control Study.

BACKGROUND: Anti-N-methyl-D-aspartate receptor encephalitis (ANMDARE) is a neuroimmunological disorder that frequently improves with immunotherapy. Symptomatic treatment with antipsychotics is common in the early stages when psychiatric symptoms predominate, and their use has been associated with serious side effects including neuroleptic malignant syndrome (NMS). The observation of an adverse response to antipsychotics, raising the suspicion of NMS, has been included as a criterion for possible autoimmune psychosis. METHODS: This case-control study included patients who received antipsychotics before referral to the National Institute of Neurology and Neurosurgery of Mexico, where they were diagnosed as having definite ANMDARE, and patients with ANMDARE who did not receive antipsychotics before referral. The neurologic and systemic features that are used to measure an adverse response to antipsychotics, raising the suspicion of NMS, were measured in both groups, including akinesia, autonomic instability, generalized rigidity, elevated concentrations of creatine phosphokinase, and hyperthermia. A logistic regression analysis was used to determine the relationship between the previous use of antipsychotics and the occurrence of NMS-like reactions. RESULTS: A total sample of 112 patients with definite ANMDARE were included in the study. Fifty patients received antipsychotics before being referred to our institution. In this group, thirty-six patients (72%) were initially classified as having an adverse response, raising the suspicion of NMS, with the following features: akinesia (64%), autonomic instability (58%), generalized rigidity (52%), elevated concentrations of creatine phosphokinase (50%), and hyperthermia (14%). Six patients fulfilled the criteria for NMS (12%). The comparison with patients who did not receive antipsychotics before the clinical assessment did not show a significant difference between groups regarding the frequency of akinesia, autonomic instability, generalized rigidity, elevated concentrations of creatine phosphokinase, or hyperthermia. Among different antipsychotics, only haloperidol was significantly associated with generalized rigidity as compared to patients who did not receive antipsychotics. CONCLUSIONS: Our study supports previous observations about the high frequency of autonomic dysfunction, hyperthermia, tachycardia, rigidity, and elevated creatine phosphokinase levels in patients with anti-NMDAR encephalitis following the administration of antipsychotic medications. Nevertheless, our study does not suggest a causal link between atypical antipsychotics and the onset of these neurological symptoms, as they were equally frequent among the group of patients who did not receive antipsychotic treatment.

Sural nerve involvement in Guillain-Barré syndrome: Clinical and prognostic implications. A prospective cohort.

BACKGROUND: Sural sparing is common in Guillain-Barré syndrome (GBS). However, one third of patients have sural nerve compromise. Its clinical implications associated factors and short-term prognosis are still unknown. The objective of this study is to identify if sural nerve compromise is associated with a worse prognosis and to describe clinical and electrophysiological characteristics in Guillain-Barré syndrome. MATERIALS AND METHODS: We prospectively analyzed patients with Guillain-Barré diagnosis with vs without sural nerve compromise. All patients underwent nerve conduction studies within the first 3 days of hospital admission. Clinical and electrophysiological characteristics were compared between groups. RESULTS: 174 patients were included in this study. Acute inflammatory demyelinating polyneuropathy was the predominant variant (43.7 %). Thirty percent of patients had sural nerve involvement. In the comparative analysis between affected vs unaffected sural groups, age ≥50 years and Guillain-Barré disability score ≥3 demonstrated a statistically significant difference. Regarding short-term recovery period for independent walking, there was no significant difference. In the multivariate analysis, age ≥50 years was identified as independent factors for sural nerve compromise on admission. CONCLUSION: sural nerve compromise occurs in 30 % of patients with GBS and is not associated with a worse functional prognosis. Age ≥50 years was identified as an independent factor for sural nerve compromise.

Dysautonomia and related outcomes in Guillain-Barre syndrome.

BACKGROUND: Guillain-Barre syndrome (GBS) presents an annual incidence of 1.2-2.3 per 100,000. Sympathetic and parasympathetic nervous systems' peripheral control of visceral organs is affected by GBS aberrant immune response. Associated cardiovascular, gastrointestinal, sudomotor, pupillary, and other systems disturbances cause significant morbidity and mortality. This study aims to evaluate the dysautonomia spectrum in GBS patients, its relationship with patient outcomes, and compare it with those without autonomic disturbances. METHODS: We performed an ambispective review study of patients with GBS and dysautonomia admitted to the Institute of Neurology from 2017 to 2021. We recorded demographics, comorbidities, nerve conduction studies, clinical course, hospital complications, and functional outcomes. RESULTS: We included 214 patients, mean age 46.44 ± 16.49 years, 51 (31 %) presented dysautonomia, hypertension in most of the patients 39 (84.8 %), hypotension 35 (76.1 %), tachycardia 35 (76.1 %), enteric dysmotility 35 (76.1 %), and need for vasopressor 27 (58.7 %) were common characteristics. Twenty (39.2 %) with a demyelinating form and twenty (39.2 %) with an axonal motor form. The bivariate analysis report factors associated with dysautonomia, were lower cranial nerves (VII, IX, X) involvement (p = 0.002), need for mechanical ventilation (p = 0.0001) and intensive care (p = 0.0001), higher mEGOS (p = 0.05), EGRIS (p = 0.004), GBS disability score (p = 0.004), and delirium presence (p = 0.001). Kaplan-Meier survival analysis showed that dysautonomic patients needed more days for the independent walk (p = 0.004). There was no associated mortality. CONCLUSIONS: Autonomic dysfunction in GBS significantly affects the peripheral nervous system. With consequently worse functional results. Further investigation needs to clarify whether more aggressive treatment is beneficial in this category of GBS.

Deltoid muscle strength and autonomic dysfunction as independent risk factors for invasive mechanical ventilation in patients with Guillain-Barré syndrome.

BACKGROUND: Almost a third of patients with Guillain-Barré Syndrome (GBS) require mechanical ventilation, increasing mortality by 15-30% and proving poor functional outcomes. The Erasmus GBS Respiratory Insufficiency Score (EGRIS) is the most frequently used scale to assess probability of respiratory insufficiency within the first week of admission. We aim to determine other clinical and electrophysiological prognostic factors for invasive mechanical ventilation (IMV) in patients with GBS. MATERIAL AND METHODS: A cross-sectional ambispective cohort study was carried out in a referral center in Mexico City, from January 2015 to December 2019. Baseline demographics, MRC score, Hughes scale, EGRIS, dysautonomia and nerve conduction studies were performed on admission in GBS patients that required IMV. A multivariable analysis for IMV and a survival analysis for independent walk in prolonged-IMV (>14 days) were performed. RESULTS: Forty-nine (32%) out of 153 GBS patients required IMV. Statistically significant prognostic factors in multivariable analysis were deltoid muscle strength ≤2 [OR 7.1 (1.6-31.1)], EGRIS [OR 2.5 (1.3-4.6)] and autonomic dysfunction [OR 6.6 (2.0-22.0)]. Electrodecrement <1 mV in the compound muscle action potential (CMAP) of distal motor median nerve was more prevalent in prolonged-IMV patients (44.8% vs. 21%, p = .049). A significant minor prevalence of prolonged-IMV patients regain independent walk at 6 months using the Kaplan-Meier method (log rank test p < .001). CONCLUSIONS: We provide new specific clinical (deltoid muscle strength and autonomic dysfunction) and electrophysiological variables to discriminate GBS patients that will require IMV.

Prognostic Implications of Early Albuminocytological Dissociation in Guillain-Barré Syndrome.

BACKGROUND: Half of Guillain-Barré syndrome (GBS) present elevated cerebrospinal fluid (CSF) protein levels within 1 week since symptom onset and 80% within 2 weeks. Our objective was to determine the clinical and prognostic implication of albuminocytological dissociation in early GBS. METHODS: An ambispective cohort study was conducted. Good outcome was considered if the patient was able to walk unaided (Guillain-Barré disability score [GDS] ≤ 2 points) at 3-month follow-up. Patients were classified into two groups: with and without albuminocytological dissociation; we compared clinical and paraclinic characteristics between the groups. We analyzed clinical and electrophysiological factors related to presenting early dissociation through a multivariate model. RESULTS: We included 240 patients who fulfilled Asbury criteria for GBS. On further selection, only 94 patients fulfilled inclusion. Mean age was 45.94 ± 17.1 years and 67% were male. Median time from symptom onset to admission was 5 days (IQR 3-6). Regarding albuminocytological dissociation and electrophysiological variants, we found a significant difference: acute inflammatory demyelinating polyneuropathy (AIDP) [60.6% vs 26.2%, p = 0.002], acute motor axonal neuropathy (AMAN) [21.2% vs 49.1%, p = 0.009] and acute motor sensory axonal neuropathy (AMSAN) [12.1% vs 1.6%, p = 0.05]. We did not observe significant differences in recovery of independent walking in short term between both groups. The presence of conduction block in any variant (OR 3.21, 95% CI 1.12-9.16, p = 0.02) and absence of sural registration (OR 5.69, 95% CI 1.48-21.83, p = 0.011) were independent factors related to early dissociation. CONCLUSIONS: Early dissociation (<7 days) is not associated with any particular clinical feature or unfavorable outcome. It is more common to see in AIDP rather than axonal variants.

Very low peroneal nerve compound muscle action potential amplitude predicts poor outcome in patients with Guillain-Barré syndrome: a prospective cohort.

INTRODUCTION: Twenty percent of patients with Guillain-Barré syndrome (GBS) have poor outcomes despite proper management. The aim of the study was to characterize electrophysiological factors related to poor outcome in patients with GBS. METHODS: We conducted an observational study from a prospective cohort of 91 patients with GBS in a tertiary healthcare center in Mexico, from 2017 to 2019. Demographics and nerve conduction studies were performed on admission, and a 3-month follow-up for GBS disability score was ensued, allocating patients in good (GBS disability score ≤ 2) and poor outcome (GBS disability score ≥ 3) groups. A logistic regression analysis for independent walk at 3 months was performed. Kaplan-Meier estimator curves for independent walk in very low (< 20% LLN) and low-normal ( ≥20% LLN) peroneal nerve CMAPs are presented. RESULTS: From the 91 GBS patients included, 37 (40.6%) did not regain independent walk at 3 months. Axonal variants were more common in the poor outcome group (31.4% vs 59.4%, p = 0.01) as well as AIDP variants with motor conduction block (6.6% vs 42.4%, p = 0.018). Univariable analysis was statistically significant for very low median, ulnar, tibial, and peroneal CMAP amplitudes in poor outcome patients; however, multivariable analysis was only significant for very low peroneal nerve CMAP amplitude (OR 3.6 [1.1-11.5, p = 0.024]). Conversely, a greater proportion of GBS patients with low-normal CMAPs recovered independent walk at 90 days (75% vs 30%, p < 0.001). CONCLUSION: Severe axonal injury of the peroneal nerve, axonal, and AIDP with motor conduction block variants predicts worse functional outcome regarding independent walk at 3 months.

Inpatient Delirium in Guillain-Barré Syndrome: Frequency and Clinical Characteristics in a Mexican Hospital.

Background Delirium has a prevalence of 14%-56% in hospitalized patients. Risk factors include advanced age, invasive mechanical ventilation (IMV), and prolonged intensive care unit stay. Neuropsychiatric symptoms have been reported to be related to autoimmune responses secondary to Guillain-Barré syndrome (GBS) with direct involvement of the central nervous system (CNS) or to delirium. There are few reports of the frequency of delirium in patients with Guillain-Barré syndrome (GBS). Objective To describe the frequency of and the characteristics associated with delirium in patients with GBS. Material and methods A single-center, cross-sectional study was conducted in patients with GBS diagnosis between 2015 and 2019. The diagnosis of delirium was made using the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) criteria. We compared patients with and without delirium. We performed both univariate and multivariate analyses to identify factors associated with delirium. Results A total of 154 patients with GBS were included, of which 20 (12.9%) fulfilled the DSM-5 criteria for delirium. The mean age was 48 ± 18.2 years, the median Medical Research Council (MRC) sum score was 29.3 ± 21.9 points, 65% had bulbar cranial nerve involvement, 80% presented autonomic dysfunction, 85% had ICU stay, and 90% had mechanical ventilation requirement. In the multivariate analysis, the following were the independent factors for the development of delirium: age ≥ 60 (odds ratio (OR): 5.7; 95% confidence interval (CI): 1.3-23.5), time from symptom onset to admission ≤ 3 days (OR: 4.3; 95% CI: 1.1-16.8), autonomic dysfunction (OR: 13.1; 95% CI: 3-56), and intensive care unit stay (OR: 9.5; 95% CI: 2.1-42.6). Conclusion Delirium is not frequent in patients with Guillain-Barré syndrome. Patients with advanced age, rapid motor progression, bulbar cranial nerve involvement, prolonged intensive care unit stay, and mechanical ventilation need are more likely to present delirium.

[Neuropsychiatric aspects of anti-NMDA receptor encephalitis]. / Aspectos neuropsiquiátricos de la encefalitis por anticuerpos contra el receptor NMDA.

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a potentially lethal clinical entity that belongs to the group of antibody-mediated encephalitis against synaptic proteins. It shows IgG antibodies against the NR1 subunit of the NMDA receptor (NMDA-R), which have been associated with psychiatric and neurological symptoms that develop in stages in the course of the disease. The predominance of neuropsychiatric symptoms in the early stages of the disease results in an increased number of patients that search for psychiatric evaluation as their first contact with the health system. For this reason, it is vital for physicians to recognize this entity as an important differential diagnosis in their clinical practice because, despite the severity of this condition, more than 75 % of patients achieve a substantial recovery with appropriate and timely treatment. We present a review of the literature on this disease, with special emphasis on the neuropsychiatric aspects.

La encefalitis por anticuerpos contra el receptor anti-N-metil-D-aspartato (NMDA) es una entidad clínica potencialmente letal perteneciente al grupo de las encefalitis mediadas por anticuerpos contra proteínas sinápticas. En esta se demuestran anticuerpos IgG contra el receptor de NMDA (NMDAr), asociados con síntomas psiquiátricos y neurológicos que se desarrollan por estadios en el curso de la enfermedad. El predominio de síntomas neuropsiquiátricos en las etapas tempranas provoca que un elevado porcentaje de pacientes busquen evaluación psiquiátrica como un primer contacto con el sistema de salud. Por esta razón, es vital que los médicos reconozcan esta entidad como un diagnóstico diferencial importante en la práctica clínica, puesto que, a pesar de la gravedad de esta condición, más de 75 % de los pacientes logra una recuperación sustancial con un tratamiento adecuado y oportuno. Presentamos una revisión de la literatura sobre esta enfermedad, con especial énfasis en los aspectos neuropsiquiátricos.

[Autoinmune psychosis]. / Psicosis autoinmune.

With the advent of the description of autoimmune encephalitis by different neuronal cell-surface antibodies (anti-NMDAr, among others) and that psychosis may be the only manifestation without neurological symptoms (epilepsy, movement disorders, autonomic dysfunction, altered state of consciousness) in 6.5 % of patients, the term "autoimmune psychosis" has become remarkably interesting among researchers. In 2020, an international consensus for the description and diagnostic approach of autoimmune psychosis was created. Through this consensus, by taking different criteria into account, the definition of autoimmune psychosis was proposed at different degrees of certainty (possible, probable, and defined). The purpose of these criteria is to underpin the autoimmune origin in patients who present psychosis with atypical characteristics, thus justifying the realization of laboratory studies and complementary clinical tests (lumbar puncture, electroencephalogram, and magnetic resonance imaging of the brain); in addition, these criteria are applied in patients with psychosis without neurological symptoms that do not fully meet the criteria of autoimmune encephalitis. As in autoimmune encephalitis, the early initiation of immunotherapy has a direct impact on the functional prognosis of patients, so an early initiation of treatment must be considered in clinical scenarios of probable or definite autoimmune psychosis.

Con el advenimiento de la descripción de las encefalitis autoinmunes por diferentes anticuerpos neuronales de superficie (anti-NMDAr, entre otros) y que la psicosis puede ser la única manifestación sin síntomas neurológicos (epilepsia, alteraciones del movimiento, disautonomías, alteración del despierto) en 6.5 % de los pacientes, el término psicosis autoinmune ha retomado gran interés entre los investigadores. En 2020 se creó un consenso internacional para la descripción del término "psicosis autoinmune" y su abordaje diagnóstico. A través de este consenso, considerando diferentes criterios, se propone la definición de psicosis autoinmune en diferentes grados de certeza (posible, probable y definida). La finalidad de estos criterios es sustentar el origen autoinmune en pacientes que presenta psicosis con características atípicas, justificando así la realización de estudios de laboratorio y gabinete complementarios (punción lumbar, electroencefalograma, imagen de resonancia magnética de encéfalo); además, estos criterios se aplican a pacientes con psicosis sin síntomas neurológicos que no cumplen completamente con los criterios de encefalitis autoinmune. El inicio temprano de la inmunoterapia impacta directamente en el pronóstico funcional de los pacientes; se debe considerar el inicio temprano de tratamiento en cuadros clínicos de psicosis autoinmune probable o definida.

Pharyngeal-Cervical-Brachial Variant of Guillain-Barré Syndrome.

Guillain-Barré syndrome (GBS) represents the main cause of flaccid paralysis worldwide. Although most cases have a typical clinical presentation of symmetric ascending flaccid paralysis with areflexia or hyporeflexia, this disease may present as multiple clinical entities, therefore representing a diagnostic challenge for physicians, who should consider these variants when assessing neuropathies. The pharyngeal-cervical-brachial (PCB) variant of Guillain-Barré syndrome is defined by rapidly progressive oropharyngeal and cervicobrachial weakness associated with hyporeflexia or areflexia in the upper limbs. It is present in 3% of all Guillain-Barré syndrome cases and is characterized by axonal rather than demyelinating neuropathy.  We present a pharyngeal-cervical-brachial variant case in a 55-year-old male who presented to the neurological emergency department with a three-day history of progressive and continuous dysarthria, dysphagia to solids, and tongue numbness, later developing paresthesia and weakness in the upper limbs. On physical examination, slight bilateral facial weakness, limited soft palate elevation, absent gag reflex, and limited tongue lateralization were found. Additionally, weakness was found bilaterally in the upper limbs and the flexor and extensor muscles of the neck with preserved muscle strength in the lower limbs. The patient presented upper limb hyporeflexia with lower limb hyperreflexia. A lumbar puncture was performed, revealing protein levels of 35 mg/dL and no cells in the cerebrospinal fluid. Nerve conduction studies reported acute motor and sensory axonal neuropathy (AMSAN). Management of the patient consisted of IgG administration and nasogastric tube insertion.

Vacuolar Myopathy Associated to CACNA1S Mutation as a Rare Cause of Late-Onset Limb-Girdle Myopathy: A Case Report.

Late-onset limb-girdle myopathies pose a diagnostic challenge. The most common etiologies are inflammatory, followed by genetic and metabolic. Rare cases include limb-girdle dystrophies and permanent myopathies (vacuolar), such as those associated with hypokalemic periodic paralysis (HypoPP). We present the case of a 59-year-old male who initiated with episodic acute severe weakness when he was 11, during which serum potassium levels of <2.5 meq/L were revealed during workup. Potassium reposition reversed these episodes. They occurred every three to five years, and the last episode was five years prior to the current illness. When he was 58, he presented progressive pelvic girdle weakness. On examination, he presented decreased strength in the iliopsoas and quadriceps. The laboratory results showed mildly elevated creatine kinase. Muscle biopsy revealed a vacuolar myopathy, and genetic testing identified a pathogenic variant in the CACNA1S gene, locus 1q32.1 [c.3716G> A (p.Arg1239His), heterozygous state].

Prognostic Factors in Elderly Patients With Guillain-Barré Syndrome: Does Age Matter?

INTRODUCTION: Twenty to 40% of Guillain Barré syndrome (GBS) patients will not be able to walk independently despite effective treatment. Older patients carry additional risks for worse outcomes. METHODS: A single center, ambispective cohort study was performed. Only subjects ≥18 years with a 3-month follow-up were included. Elderly patients were considered as a whole if ≥ 60 years. Demographics, CSF and nerve conduction studies were compared. A binomial logistic regression and Kaplan-Meier analyses were carried out to estimate good prognosis (Hugues ≤2) at 3-month follow-up. RESULTS: From 130 patients recruited, 27.6% were elderly adults. They had a more severe disease, higher mEGOS and more cranial nerve involvement. Age ≥70 years, invasive mechanical ventilation and axonal subtype, portrayed an unfavorable 3-month outcome. Further analysis demonstrated an earlier recovery in independent walk at 3 months for patients <70 years. CONCLUSIONS: Elderly patients with GBS have a more severe disease at admission and encounter worse prognosis at 3-month follow-up, especially those above 70 years.

[Obesity in adulthood is associated with the severity of asthma, but not with asthma control]. / La obesidad en adultos está asociada con la gravedad del asma, pero no con el control del asma.

BACKGROUND: The impact of obesity on the severity of asthma continues to be a cause of controversy. OBJECTIVE: To compare the severity of asthma and asthma control in obese patients with non-obese patients. METHODS: A cross-sectional study which included 188 patients with asthma, of ≥ 18 years of age, who were selected consecutively. The patients were categorized and compared based on the presence or absence of obesity. In order to establish an association between variables, logistic regression analyses were performed. RESULTS: In total, 111/188 of the patients had obesity; these patients were older than those without obesity (35.9 ± 15.3 years vs. 44.4 ± 13.8 years, p <0.001). No significant difference was observed in the groups regarding sex, total IgE serum concentration, peripheral blood eosinophil count, personal history of atopic diseases, frequency of allergic sensitization, hospitalization for asthma, and asthma control. Overall, obesity was significantly associated with moderate-severe asthma (OR = 1.82, p = 0.047), but not with asthma control (p = 0.094). CONCLUSIONS: Our results suggest that patients with asthma and obesity are older and that their pulmonary function is worse, which is reflected in a greater level of severity of asthma.

Antecedentes: El impacto de la obesidad sobre la gravedad del asma contiúa siendo motivo de controversia. Objetivo: Comparar la gravedad y el control del asma entre pacientes con obesidad y sin obesidad. Métodos: Estudio transversal que incluyó a 188 pacientes con asma, con edad ≥ 18 años, seleccionados consecutivamente. Los pacientes fueron categorizados y comparados de acuerdo con la presencia de obesidad o no. Para establecer asociación entre variables se realizó análisis de regresión logística. Resultados: En total, 111 pacientes tenían obesidad; su edad fue mayor que la de los pacientes sin obesidad (35.9 ± 15.3 años versus 44.4 ± 13.8 años, p < 0.001). No se observó diferencia significativa entre los grupos respecto a sexo, concentración sérica total de IgE, número de eosinófilos en sangre periférica, historia personal de enfermedad atópica, frecuencia de sensibilización alérgica, hospitalización por asma y control del asma. En general, la obesidad se asoció significativamente con el asma moderada o grave (RM = 1.82, p = 0.047), pero no lo hizo con el control del asma (p = 0.094). Conclusiones: Nuestros resultados sugieren que los pacientes con asma y obesidad tienen mayor edad y peor función pulmonar, la cual se reflejada en mayor gravedad del asma.

Rituximab in Refractory Myasthenia Gravis: Experience in a Single Healthcare Center in Mexico.

BACKGROUND: Ten to fifteen percent of patients with myasthenia gravis (MG) have treatment-refractory disease. In short series and case reports, rituximab has proven to be effective in refractory MG. METHODS: A retrospective, longitudinal study was conducted. Recruitment was performed in an MG cohort from a single third-level healthcare center in Mexico. The selection included refractory MG patients that were treated with rituximab. Response after rituximab therapy was assessed with MG composite score (MGCS) and prednisone dose reduction at 6, 12, and 18 months after initiation. Wilcoxon signed-rank test was used to evaluate differences between related groups for non-continual variables. P<0.05 was considered statistically significant. RESULTS: Ten patients (7%) fulfilled criteria for refractory MG, and eight of them were treated with rituximab. The mean age at MG diagnosis was 25.5 (±2) years, with a female predominance (75%). All our patients (100%) had positive acetylcholine receptor (AchR) antibodies. The median MG duration was six years (interquartile range [IQR] 4.2-6) before rituximab initiation. All patients were previously treated with azathioprine and 50% additionally with cyclophosphamide. The median prednisone doses before rituximab treatment and 18-month follow-up were 50 mg (IQR 30-50 mg) and 10 mg (IQR 0-20 mg), respectively (p=0.011). The median baseline MGCS and at 18-month follow-up were 19.5 (IQR 11-31) and 6 (IQR0-16), respectively (p = 0.012). CONCLUSION: Rituximab appears to be associated with clinical improvement and prednisone dose reduction in Latin-American patients diagnosed with anti-AchR MG. Our findings need to be interpreted in light of the limitations mentioned.

Classic and overlapping Miller-Fisher syndrome: clinical and electrophysiological features in Mexican adults.

Classic and overlapping Miller-Fisher syndrome (MFS) have divergent clinical courses. Few studies have addressed the electrophysiological evaluation of MFS patients, most of them carried out in Asia. This work describes and compares their clinical and neurophysiological characteristics. From a Guillain-Barré syndrome (GBS) patient cohort, we made a selection of twenty MFS cases. We defined classic and overlapping MFS, as stated by Wakerley et al. (Nat Rev Neurol 10(9):537-544, 2014). We describe and compare clinical, biochemical, and electrodiagnostic parameters between groups. Seventy-five percent were men, mean age was 42.2 ± 13.6 years, and 45% had a Hughes score ≥ 3. MFS/GBS was the most frequent clinical subtype with 50%. Almost one-third had unaltered electrophysiological studies. Comparative analysis between groups showed statistically significant differences in length of stay, dysautonomia presence, and treatment type. Kaplan-Meier survival analysis showed that 100% of the patients had an independent walk at 3 months. This study reports Mexican MFS patient's characteristics and represents the most extensive case series in Latin America. We observed a high proportion of overlapping syndromes, a good recovery profile, and no significant severe complications.

Advances in imaging technologies for the assessment of peripheral neuropathies in rheumatoid arthritis.

Peripheral neuropathy in patients with rheumatoid arthritis is associated with a maladaptive autoimmune response that may cause chronic pain and disability. Nerve conduction studies are the routine method performed when rheumatologists presume its presence. However, this approach is invasive, may not reveal subtle malfunctions in the early stages of the disease, and does not expose abnormalities in structures surrounding the nerves and muscles, limiting the possibility of a timely diagnosis. This work aims to present a narrative review of new technologies for the clinical assessment of peripheral neuropathy in Rheumatoid Arthritis. Through a bibliographic search carried out in five repositories, from 1990 to 2020, we identified three technologies that could detect peripheral nerve lesions and perform quantitative evaluations: (1) magnetic resonance neurography, (2) functional magnetic resonance imaging, and (3) high-resolution ultrasonography of peripheral nerves. We found these tools can overcome the main constraints imposed by the previous electrophysiologic methods, enabling early diagnosis.

Mirtazapine Risk of Hyponatremia and Syndrome of Inappropriate Antidiuretic Hormone Secretion in Adult and Elderly Patients: A Systematic Review.

Hyponatremia is the most common fluid and electrolyte imbalance in hospitalized patients. Among hyponatremia causes, syndrome of inappropriate antidiuretic hormone secretion is a condition characterized by excessive release of antidiuretic hormone from the pituitary gland or nonpituitary sources. One of the most common drugs associated with hyponatremia is selective serotonin reuptake inhibitors, especially in elderly patients. Therefore, distinct therapeutic alternatives are essential for patients having risk factors for hyponatremia or syndrome of inappropriate antidiuretic hormone secretion development.  The present article aims to review the available literature evaluating mirtazapine-induced hyponatremia or syndrome of inappropriate antidiuretic hormone secretion in adult or elderly patients in order to determine the incidence of these adverse effects and analyze the existence of any correlation between the administered dose of mirtazapine and serum sodium levels. A systematic search was conducted, using key terms from the research topic, their synonyms, and Boolean/logic operators. From this evidence pool, inclusion and exclusion criteria were applied. We abstracted population characteristics and clinical endpoints. Relevant data from selected studies was abstracted and subject to statistical analysis.  A total sample size of 30,851 patients treated with mirtazapine was included. Mirtazapine-induced hyponatremia incidence was 3.26% (95% CI 3.06-3.45%), with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) the most probable underlying cause. Among case series and case reports evaluated (n=7), hyponatremia and SIADH were more frequent in female patients (71.4%) and the most frequent clinical manifestations included confusion (57%), somnolence (42%), and altered speech (28%). Mean serum sodium levels were (117 mEq/L, ranging from 113-130 mEq/L). The average time lapse between mirtazapine administration and clinical findings was 34 days. The Spearman's rank correlation coefficient between mirtazapine dosage and serum sodium levels was -0.3181 with a p-value >0.05.  In conclusion, mirtazapine presents a moderate risk of hyponatremia and should be considered as an alternative therapy in patients requiring antidepressants with risk factors for this preventable adverse effect.

Electrophysiological subtypes and associated prognosis factors of Mexican adults diagnosed with Guillain-Barré syndrome, a single center experience.

BACKGROUND: The clinical characteristics of electrophysiological subtypes and prognostic factors of Mexican adults diagnosed with Guillain-Barré Syndrome (GBS) have not been described. MATERIALS AND METHODS: A single center, ambispective, cohort study was performed (2015-2019). GBS was defined following the Asbury and Cornblath criteria. Electrodiagnosis was made according to Hadden criteria. Clinical, biochemical and electrodiagnostic parameters were described, compared and analyzed using a multivariate model. Only patients who completed a 3-month follow-up were included. RESULTS: 137 GBS patients (92 males; mean age 46.6 ± 16.6).132 (96.3%) underwent an electrodiagnostic assessment.68 (51.5%) were classified as axonal GBS, with further classified into two groups: acute motor axonal neuropathy (AMAN) 45.4%, and acute motor and sensory axonal neuropathy (AMSAN) 8,6%. The following characteristics were lower in the AMAN group: Medical Research Counsel sumscore (MRC) 30.1 ± 16.3 vs 36.4 ± 14.4, unilateral facial palsy 10% vs 25.9% and albuminocytologic dissociation 41.3% vs. 71.7%.Multivariate analysis found AMAN as an independent predictor of an unfavorable outcome OR: 3.34 (p = 0.03) CONCLUSIONS: AMAN subtype is the most frequent presentation of GBS in Mexican adult patients and an independent predictor of inability to walk independently at 3 months after discharge.

Intravenous cyclophosphamide monthly pulses in refractory myasthenia gravis.

INTRODUCTION: Refractory myasthenia gravis (MG) is defined as a failure to respond adequately to conventional therapies, the inability to reduce immunosuppressive therapy without clinical relapse or the need for ongoing rescue therapy, severe adverse effects from immunosuppressive therapy (treatment intolerant) or frequent myasthenic crisis even on therapy. Cyclophosphamide (CYC) is a DNA alkylating agent that causes important interference in transcription processes and DNA replication, it has been used in refractory MG with controversial results. We aim to determine the efficacy of CYC in refractory MG in the Mexican population. METHODS: In an observational, longitudinal retrospective study, we identified eight refractory MG patients treated with 30-50 mg/kg monthly CYC for at least 6 months. The efficacy was assessed by Osserman scale considering significant improvement a ≥ 1 point reduction and Myasthenia Gravis Composite Scale. The relapse-free and remission-free period were also calculated using the Kaplan-Meier statistic. RESULTS: Clinical improvement was achieved in 75% of the patients. According to the Kaplan-Meier analysis, the median progression-free survival (PFS) was 9 (6.2-11.5) months and the median time to progression (TTP) was 4 (1-8) months. Response was independent of patient's characteristics, except for the MG age of onset (p = 0.0025). CONCLUSIONS: CYC was effective in all patients with refractory MG for a mean of 9 months, with worsening thereafter, which could be associated with low cumulative dose. The symptomatic improvement with CYC was noted within the 1st month. We conclude that CYC is effective as an induction to remission therapy, although our data suggest it is not effective as a long-term therapy.