Pilot trial on awake surgery for low grade AVMs in speech area and systematic review of the literature.

OBJECTIVE: One of the pressing constraints in the treatment for arteriovenous malformations (AVM) is the potential development of new neurological deficits, mainly when the AVM is in an eloquent area. The risk of ischemia when an "en passage" arterial supply is present is not negligible. In this regard, awake surgery holds promise in increasing the safety of low-grade AVMs resection. METHODS: We conducted a pilot trial on 3 patients with low-grade AVMs affecting speech areas to evaluate the safety of awake craniotomy. Each feeder was temporarily clipped before the section. Also, we performed a systematic review to analyze the existing data about the impact of awake surgery in eloquent AVM resection. RESULTS: None of the 3 patients presented with neurological deficits after the procedure. Awake craniotomy was useful in one case, as it allowed the detection of speech arrest during the temporal clipping of one of the feeders. This vessel was identified as an "en passage" vessel, closer to the nidus. The second attempt revealed the feeder of the AVM which was sectioned. Systematic review yielded 7 studies meeting our inclusion criteria. Twenty-six out of 33 patients included in these studies presented with AVM affecting speech area. Only 2 studies included the motor evoked potentials, 6 studies used direct cortical and subcortical stimulation. In all the studies asleep-awake-asleep (AAA) technique was used. CONCLUSIONS: Awake craniotomies are safe procedures and may be helpful in avoiding ischemic complications in low-grade AVMs, either affecting eloquent areas and/or when "en passage" feeders are present.

Modelos experimentales murinos en la esclerosis lateral amiotrófica. Puesta al día / Murine experimental models of amyotrophic lateral sclerosis: An update

Introducción: La esclerosis lateral amiotrófica (ELA) es una enfermedad neurodegenerativa, progresiva y de etiología desconocida caracterizada por la degeneración de motoneuronas superiores e inferiores. Aproximadamente el 90% de los casos de ELA son esporádicos, mientras que el 10% restante se consideran familiares. Independientemente de si son familiares o esporádicas, los pacientes desarrollan una debilidad progresiva, atrofia muscular con espasticidad y contracturas. Por lo general, la esperanza de vida en los pacientes de ELA es de 2 a 5 años. Desarrollo: Los modelos in vivo han ayudado a explicar la etiología y la patogénesis, así como los mecanismos de la ELA. Sin embargo, estos mecanismos no están del todo esclarecidos aún, por lo que los modelos experimentales son fundamentales para continuar con el estudio de los mismos, así como para la búsqueda de posibles dianas terapéuticas. A pesar de que el 90% de los casos son esporádicos, la mayoría de los modelos utilizados hasta la actualidad para estudiar la patogénesis están basados en las mutaciones genéticas asociadas a la enfermedad familiar, lo que provoca que la patogénesis de la ELA esporádica no sea aún conocida. Por tanto, sería fundamental el estudio de la enfermedad en modelos basados en la enfermedad esporádica. Conclusión: En el presente artículo se han revisado los principales modelos experimentales, tanto genéticos como esporádicos, utilizados en el estudio de esta enfermedad, enfocándonos en los que se han desarrollado utilizando el roedor como plataforma experimental.(AU)

Introduction: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease whose aetiology is unknown. It is characterised by upper and lower motor neuron degeneration. Approximately 90% of cases of ALS are sporadic, whereas the other 10% are familial. Regardless of whether the case is familial or sporadic, patients will develop progressive weakness, muscle atrophy with spasticity, and muscle contractures. Life expectancy of these patients is generally 2–5 years after diagnosis. Development: In vivo models have helped to clarify the aetiology and pathogenesis of ALS, as well as the mechanisms of the disease. However, as these mechanisms are not yet fully understood, experimental models are essential to the continued study of the pathogenesis of ALS, as well as in the search for possible therapeutic targets. Although 90% of cases are sporadic, most of the models used to study ALS pathogenesis are based on genetic mutations associated with the familial form of the disease; the pathogenesis of sporadic ALS remains unknown. Therefore, it would be critical to establish models based on the sporadic form. Conclusion: This article reviews the main genetic and sporadic experimental models used in the study of this disease, focusing on those that have been developed using rodents.(AU)

Murine experimental models of amyotrophic lateral sclerosis: an update.

INTRODUCTION: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease whose aetiology is unknown. It is characterised by upper and lower motor neuron degeneration. Approximately 90% of cases of ALS are sporadic, whereas the other 10% are familial. Regardless of whether the case is familial o sporadic, patients will develop progressive weakness, muscle atrophy with spasticity, and muscle contractures. Life expectancy of these patients is generally 2 to 5 years after diagnosis. DEVELOPMENT: In vivo models have helped to clarify the aetiology and pathogenesis of ALS, as well as the mechanisms of the disease. However, as these mechanisms are not yet fully understood, experimental models are essential to the continued study of the pathogenesis of ALS, as well as in the search for possible therapeutic targets. Although 90% of cases are sporadic, most of the models used to study ALS pathogenesis are based on genetic mutations associated with the familial form of the disease; the pathogenesis of sporadic ALS remains unknown. Therefore, it would be critical to establish models based on the sporadic form. CONCLUSIONS: This article reviews the main genetic and sporadic experimental models used in the study of this disease, focusing on those that have been developed using rodents.

Exonic variants of the P2RX7 gene in familial multiple sclerosis.

INTRODUCTION: Several studies have analysed the presence of P2RX7 variants in patients with MS, reporting diverging results. METHODS: Our study analyses P2RX7 variants detected through whole-exome sequencing (WES). RESULTS: We analysed P2RX7, P2RX4, and CAMKK2 gene variants detected by whole-exome sequencing in all living members (n = 127) of 21 families including at least 2 individuals with multiple sclerosis. P2RX7 gene polymorphisms previously associated with autoimmune disease. Although no differences were observed between individuals with and without multiple sclerosis, we found greater polymorphism of gain-of-function variants of P2RX7 in families with individuals with multiple sclerosis than in the general population. Copresence of gain-of-function and loss-of-function variants was not observed to reduce the risk of presenting the disease. Three families displayed heterozygous gain-of-function SNPs in patients with multiple sclerosis but not in healthy individuals. We were unable to determine the impact of copresence of P2RX4 and CAMKK2 variants with P2RX7 variants, or the potential effect of the different haplotypes described in the gene. No clinical correlations with other autoimmune diseases were observed in our cohort. CONCLUSIONS: Our results support the hypothesis that the disease is polygenic and point to a previously unknown mechanism of genetic predisposition to familial forms of multiple sclerosis. P2RX7 gene activity can be modified, which suggests the possibility of preventive pharmacological treatments for families including patients with familial multiple sclerosis.

Variant rs4149584 (R92Q) of the TNFRSF1A gene in patients with familial multiple sclerosis.

INTRODUCTION: Genomic studies have identified numerous genetic variants associated with susceptibility to multiple sclerosis (MS); however, each one explains only a small percentage of the risk of developing the disease. These variants are located in genes involved in specific pathways, which supports the hypothesis that the risk of developing MS may be linked to alterations in these pathways, rather than in specific genes. We analyzed the role of the TNFRSF1A gene, which encodes one of the TNF-α receptors involved in a signaling pathway previously linked to autoimmune disease. METHODS: We included 138 individuals from 23 families including at least 2 members with MS, and analyzed the presence of exonic variants of TNFRSF1A through whole-exome sequencing. We also conducted a functional study to analyze the pathogenic mechanism of variant rs4149584 (-g.6442643C > G, NM_001065.4:c.362 G > A, R92Q) by plasmid transfection into human oligodendroglioma (HOG) cells, which behave like oligodendrocyte lineage cells; protein labeling was used to locate the protein within cells. We also analyzed the ability of transfected HOG cells to proliferate and differentiate into oligodendrocytes. RESULTS: Variant rs4149584 was found in 2 patients with MS (3.85%), one patient with another autoimmune disease (7.6%), and in 5 unaffected individuals (7.46%). The 2 patients with MS and variant rs4149584 were homozygous carriers and belonged to the same family, whereas the remaining individuals presented the variant in heterozygosis. The study of HOG cells transfected with the mutation showed that the protein does not reach the cell membrane, but rather accumulates in the cytoplasm, particularly in the endoplasmic reticulum and near the nucleus; this suggests that, in the cells presenting the mutation, TNFRSF1 does not act as a transmembrane protein, which may alter its signaling pathway. The study of cell proliferation and differentiation found that transfected cells continue to be able to differentiate into oligodendrocytes and are probably still capable of producing myelin, although they present a lower rate of proliferation than wild-type cells. CONCLUSIONS: Variant rs4149584 is associated with risk of developing MS. We analyzed its functional role in oligodendrocyte lineage cells and found an association with MS in homozygous carriers. However, the associated molecular alterations do not influence the differentiation into oligodendrocytes; we were therefore unable to confirm whether this variant alone is pathogenic in MS, at least in heterozygosis.

Coexpresión de NG2/GFAP tras la diferenciación en células transfectadas con las mutaciones de GFAP y en células procedentes de gliomas indiferenciados / NG2 and GFAP co-expression after differentiation in cells transfected with mutant GFAP and in undifferentiated glioma cells

INTRODUCCIÓN: La enfermedad de Alexander es una enfermedad rara causada por mutaciones en el gen que codifica la proteína glial ácida fibrilar (GFAP). En un estudio previo hemos observado que la diferenciación de neuroesferas transfectadas con estas mutaciones genera un tipo celular que comparte la expresión de GFAP y NG2. OBJETIVOS: Determinar el efecto de las mutaciones en marcadores moleculares en comparación con células de glioma diferenciados que expresan simultáneamente GFAP y NG2. MÉTODOS: Se utilizaron muestras de glioblastoma humana (GLM) y neuroesferas procedentes de rata transfectadas con mutaciones de GFAP para el análisis de la expresión tras diferenciación de GFAP y NG2, así como el análisis inmunocitoquímico de diferenciación de ambos tipos celulares y detección de ambas proteínas, junto a nestina, vimentina, Olig2 y caspasa 3 a los 3 y 7 días de diferenciación. RESULTADOS: Tanto las células transfectadas con mutaciones de GFAP como las células procedentes de GLM mostraron un incremento de NG2 y GFAP. Sin embargo, la expresión de células caspasa 3 positiva era marcadamente mayor entre las células transfectadas que entre las células procedentes de GLM. CONCLUSIÓN: Nuestros resultados parecen indicar que la expresión de GFAP no es el único factor que condiciona la muerte celular en la enfermedad de Alexander y que la expresión de caspasa 3 y el potencial papel de la NG2 en incrementar la resistencia a la apoptosis en las células que coexpresan GFAP y NG2 deben ser considerados en la búsqueda de acciones terapéuticas en esta enfermedad

INTRODUCTION: Alexander disease is a rare disorder caused by mutations in the gene coding for glial fibrillary acidic protein (GFAP). In a previous study, differentiation of neurospheres transfected with these mutations resulted in a cell type that expresses both GFAP and NG2. OBJECTIVE: To determine the effect of molecular marker mutations in comparison to undifferentiated glioma cells simultaneously expressing GFAP and NG2. METHODS: We used samples of human glioblastoma (GBM) and rat neurospheres transfected with GFAP mutations to analyse GFAP and NG2 expression after differentiation. We also performed an immunocytochemical analysis of neuronal differentiation for both cell types and detection of GFAP, NG2, vimentin, Olig2, and aspase-3 at 3 and 7 days from differentiation. RESULTS. Both the cells transfected with GFAP mutations and GBM cells showed increased NG2 and GFAP expression. However, expression of caspase-3-positive cells was found to be considerably higher in transfected cells than in GBM cells. CONCLUSIONS: Our results suggest that GFAP expression is not the only factor associated with cell death in Alexander disease. Caspase-3 expression and the potential role of NG2 in increasing resistance to apoptosis in cells co-expressing GFAP and NG2 should be considered in the search for new therapeutic strategies for the disease

Will neurological care change over the next 5 years due to the COVID-19 pandemic? Key informant consensus survey. / ¿Va a cambiar la neurología tras la pandemia de COVID-19 en los próximos 5 años? Estudio de enfoque mediante informadores clave.

INTRODUCTION: The COVID-19 pandemic will give rise to long-term changes in neurological care, which are not easily predictable. MATERIAL AND METHODS: A key informant survey was used to enquire about the changes expected in the specialty over the next 5 years. The survey was completed by heads of neurology departments with broad knowledge of the situation, having been active during the pandemic. RESULTS: Despite a low level of consensus between participants, there was strong (85%) and moderate consensus (70%) about certain subjects, mainly the increase in precautions to be taken, the use of telemedicine and teleconsultations, the reduction of care provided in in-person consultations to avoid the presence of large numbers of people in waiting rooms, the development of remote training solutions, and the changes in monitoring visits during clinical trials. There was consensus that there would be no changes to the indication of complementary testing or neurological examination. CONCLUSION: The key informant survey identified the foreseeable changes in neurological care after the pandemic.

El papel del editor de una revista científica durante la pandemia del Covid-19 / The role of scientific journal editors during the COVID-19 pandemic

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La gestión de la asistencia neurológica en tiempos de la pandemia de Covid-19 / Management of neurological care during the COVID-19 pandemic

INTRODUCCIÓN: La pandemia de Covid-19 ha supuesto la necesidad de tomar decisiones para mantener la asistencia neurológica, sin precedentes. En este artículo se analiza esa toma de decisiones operativas. Desarrollo: Los autores refieren las fórmulas empleadas como son la realización de un plan de reorganización funcional, estrategias para la hospitalización y urgencias, la realización de consultas telefónicas para el mantenimiento de la atención neurológica, la asistencia en un área externa al hospital para pacientes preferentes, las decisiones sobre exploraciones complementarias y tratamientos intrahospitalarios periódicos o implantar un teléfono para la priorización de crisis epilépticas. CONCLUSIÓN: A pesar de la situación de aislamiento, los servicios de neurología deben mantener la atención de sus pacientes a través de distintas fórmulas operativas, que como cualquier elemento de gestión, deberán evaluarse

INTRODUCTION: The COVID-19 epidemic has led to the need for unprecedented decisions to be made to maintain the provision of neurological care. This article addresses operational decision-making during the epidemic. Development: We report the measures taken, including the preparation of a functional reorganisation plan, strategies for hospitalisation and emergency management, the use of telephone consultations to maintain neurological care, provision of care at a unit outside the hospital for priority patients, decisions about complementary testing and periodic in-hospital treatments, and the use of a specific telephone service to prioritise patients with epileptic seizures. CONCLUSION: Despite the situation of confinement, neurology departments must continue to provide patient care through different means of operation. Like all elements of management, these must be evaluated

Management of neurological care during the COVID-19 pandemic. / La gestión de la asistencia neurológica en tiempos de la pandemia de Covid-19.

INTRODUCTION: The COVID-19 epidemic has led to the need for unprecedented decisions to be made to maintain the provision of neurological care. This article addresses operational decision-making during the epidemic. DEVELOPMENT: We report the measures taken, including the preparation of a functional reorganisation plan, strategies for hospitalisation and emergency management, the use of telephone consultations to maintain neurological care, provision of care at a unit outside the hospital for priority patients, decisions about complementary testing and periodic in-hospital treatments, and the use of a specific telephone service to prioritise patients with epileptic seizures. CONCLUSION: Despite the situation of confinement, neurology departments must continue to provide patient care through different means of operation. Like all elements of management, these must be evaluated.

Should we expect neurological symptoms in the SARS-CoV-2 epidemic? / ¿Es esperable que haya cuadros neurológicos por la pandemia por SARS-CoV-2?

INTRODUCTION: There is growing evidence that SARS-CoV-2 can gain access to the central nervous system (CNS). We revise the literature on coronavirus infection of the CNS associated with neurological diseases. DEVELOPMENT: Neurological symptoms were rarely reported in the SARS-CoV and MERS-CoV epidemics, although isolated cases were described. There are also reports of cases of neurological symptoms associated with CoV-OC43 and CoV-229E infection. The presence of neurological lesions, especially demyelinating lesions in the mouse hepatitis virus model, may explain the mechanisms by which coronaviruses enter the CNS, particularly those related with the immune response. This may explain the presence of coronavirus in patients with multiple sclerosis. We review the specific characteristics of SARS-CoV-2 and address the question of whether the high number of cases may be associated with greater CNS involvement. CONCLUSION: Although neurological symptoms are not frequent in coronavirus epidemics, the high number of patients with SARS-CoV-2 infection may explain the presence of the virus in the CNS and increase the likelihood of early- or delayed-onset neurological symptoms. Follow-up of patients affected by the SARS-CoV-2 epidemic should include careful assessment of the CNS.

¿Es esperable que haya cuadros neurológicos por la pandemia por SARS-CoV-2? / Should we expect neurological symptoms in the SARS-CoV-2 epidemic?

INTRODUCCIÓN: Diversas evidencias sugieren que el SARS-CoV-2 puede penetrar en el sistema nervioso central (SNC). Los autores revisan los datos de la literatura sobre los hallazgos de coronavirus en el SNC asociado a enfermedades neurológicas. DESARROLLO: En las distintas epidemias con SARS-CoV y MERS-CoV la presencia de cuadros neurológicos es baja, pero se describen cuadros aislados de pacientes. También existen casos asociados a OC43-CoV y 229E-CoV. La existencia de lesiones neurológicas, especialmente desmielinizantes en el modelo MHV-CoV pueden explicar mecanismos de penetración de los CoV en el SNC y especialmente aquellos relacionados con la respuesta inmune, que puede justificar la existencia de CoV en pacientes con esclerosis múltiple. Los autores revisan aspectos diferenciales de SARS-CoV-2 y se plantean si debido al alto número de infectados, el virus puede afectar de forma mayor al SNC. CONCLUSIÓN: Aunque la presencia de síntomas neurológicos en las epidemias de CoV es baja, la mayor frecuencia de infectados por SARS-CoV-2 podría justificar el paso del virus y la posibilidad de clínica neurológica precoz o tardía con mayor incidencia. El seguimiento de los pacientes de la epidemia debe atender con cuidado a la evaluación del SNC

INTRODUCTION: There is growing evidence that SARS-CoV-2 can gain access to the central nervous system (CNS). We revise the literature on coronavirus infection of the CNS associated with neurological diseases. DEVELOPMENT: Neurological symptoms were rarely reported in the SARS-CoV and MERS-CoV epidemics, although isolated cases were described. There are also reports of cases of neurological symptoms associated with CoV-OC43 and CoV-229E infection. The presence of neurological lesions, especially demyelinating lesions in the mouse hepatitis virus model, may explain the mechanisms by which coronaviruses enter the CNS, particularly those related with the immune response. This may explain the presence of coronavirus in patients with multiple sclerosis. We review the specific characteristics of SARS-CoV-2 and address the question of whether the high number of cases may be associated with greater CNS involvement. CONCLUSIÓN: Although neurological symptoms are not frequent in coronavirus epidemics, the high number of patients with SARS-CoV-2 infection may explain the presence of the virus in the CNS and increase the likelihood of early- or delayed-onset neurological symptoms. Follow-up of patients affected by the SARS-CoV-2 epidemic should include careful assessment of the CNS

Modelos experimentales de desmielinización-remielinización / Experimental models of demyelination and remyelination

INTRODUCCIÓN: El uso de modelos experimentales en animales permite aumentar el conocimiento sobre la patología del sistema nervioso central. Sin embargo, en la esclerosis múltiple, no existe un modelo que permita una visión general de la enfermedad, de forma que es necesario utilizar una variedad de modelos que abarquen los distintos cambios que se producen. DESARROLLO: Se revisan los distintos modelos experimentales que pueden ser utilizados en la investigación en la esclerosis múltiple, tanto in vitro como in vivo. En relación a los modelos in vitro se analizan los distintos cultivos celulares y sus potenciales modificaciones así como los modelos en rodajas. En los modelos in vivo, se analizan los modelos de base inmune-inflamatoria como la encefalitis alérgica experimental en los distintos animales, además de las enfermedades desmielinizantes por virus. Por otro lado, se analizan los modelos de desmielinización-remielinización incluyéndose las lesiones químicas por cuprizona, lisolecitina, bromuro de etidio, así como el modelo de zebrafish y los modelos transgénicos. CONCLUSIONES: Los modelos experimentales nos permiten acercarnos al conocimiento de los diversos mecanismos que ocurren en la esclerosis múltiple. La utilización de cada uno de ellos depende de los objetivos de investigación que planteen

INTRODUCTION: Experimental animal models constitute a useful tool to deepen our knowledge of central nervous system disorders. In the case of multiple sclerosis, however, there is no such specific model able to provide an overview of the disease; multiple models covering the different pathophysiological features of the disease are therefore necessary. DEVELOPMENT: We reviewed the different in vitro and in vivo experimental models used in multiple sclerosis research. Concerning in vitro models, we analysed cell cultures and slice models. As for in vivo models, we examined such models of autoimmunity and inflammation as experimental allergic encephalitis in different animals and virus-induced demyelinating diseases. Furthermore, we analysed models of demyelination and remyelination, including chemical lesions caused by cuprizone, lysolecithin, and ethidium bromide; zebrafish; and transgenic models. CONCLUSIONS: Experimental models provide a deeper understanding of the different pathogenic mechanisms involved in multiple sclerosis. Choosing one model or another depends on the specific aims of the study

Experimental models of demyelination and remyelination. / Modelos experimentales de desmielinización-remielinización.

INTRODUCTION: Experimental animal models constitute a useful tool to deepen our knowledge of central nervous system disorders. In the case of multiple sclerosis, however, there is no such specific model able to provide an overview of the disease; multiple models covering the different pathophysiological features of the disease are therefore necessary. DEVELOPMENT: We reviewed the different in vitro and in vivo experimental models used in multiple sclerosis research. Concerning in vitro models, we analysed cell cultures and slice models. As for in vivo models, we examined such models of autoimmunity and inflammation as experimental allergic encephalitis in different animals and virus-induced demyelinating diseases. Furthermore, we analysed models of demyelination and remyelination, including chemical lesions caused by cuprizone, lysolecithin, and ethidium bromide; zebrafish; and transgenic models. CONCLUSIONS: Experimental models provide a deeper understanding of the different pathogenic mechanisms involved in multiple sclerosis. Choosing one model or another depends on the specific aims of the study.

NG2 and GFAP co-expression after differentiation in cells transfected with mutant GFAP and in undifferentiated glioma cells. / Coexpresión de NG2/GFAP tras la diferenciación en células transfectadas con las mutaciones de GFAP y en células procedentes de gliomas indiferenciados.

INTRODUCTION: Alexander disease is a rare disorder caused by mutations in the gene coding for glial fibrillary acidic protein (GFAP). In a previous study, differentiation of neurospheres transfected with these mutations resulted in a cell type that expresses both GFAP and NG2. OBJECTIVE: To determine the effect of molecular marker mutations in comparison to undifferentiated glioma cells simultaneously expressing GFAP and NG2. METHODS: We used samples of human glioblastoma (GBM) and rat neurospheres transfected with GFAP mutations to analyse GFAP and NG2 expression after differentiation. We also performed an immunocytochemical analysis of neuronal differentiation for both cell types and detection of GFAP, NG2, vimentin, Olig2, and caspase-3 at 3 and 7 days from differentiation. RESULTS: Both the cells transfected with GFAP mutations and GBM cells showed increased NG2 and GFAP expression. However, expression of caspase-3-positive cells was found to be considerably higher in transfected cells than in GBM cells. CONCLUSIONS: Our results suggest that GFAP expression is not the only factor associated with cell death in Alexander disease. Caspase-3 expression and the potential role of NG2 in increasing resistance to apoptosis in cells co-expressing GFAP and NG2 should be considered in the search for new therapeutic strategies for the disease.

Role of deep brain stimulation therapy in the magnetic resonance-guided high-frequency focused ultrasound era: current situation and future prospects.

Introduction: Deep brain stimulation (DBS) is a well-established treatment of movement disorders; but recently there has been an increasing trend toward the ablative procedure magnetic resonance-guided focused ultrasound (MRgFU). DBS is an efficient neuromodulatory technique but associated with surgical complications. MRIgFUS is an incision-free method that allows thermal lesioning, with fewer surgical complications but irreversible effects.Areas covered: We look at current and prospective aspects of both techniques. In DBS, appropriate patient selection, improvement in surgical expertise, target accuracy (preoperative and intraoperative imaging), neurophysiological recordings, and novel segmented leads need to be considered. However, increased number of older patients with higher comorbidities and risk of DBS complications (mainly intracranial hemorrhage, but also infections, hardware complications) make them not eligible for surgery. With MRgFUS, hemorrhage risks are virtually nonexistent, infection or hardware malfunction are eliminated, while irreversible side effects can appear.Expert commentary: Comparison of the efficacy and risks associated with these techniques, in combination with a growing aged population in developed countries with higher comorbidities and a preference for less invasive treatments, necessitates a review of the indications for movement disorders and the most appropriate treatment modalities.

La alteración de la mielina en la enfermedad de Alexander / Myelin changes in Alexander disease

Introducción: La enfermedad de Alexander (AxD) es una leucodistrofia. Su base patológica, junto a la pérdida de mielina, es la aparición de los cuerpos de Rosenthal, que son inclusiones citoplasmáticas en células astrocitarias. Mutaciones en el gen que codifica la GFAP se han identificado como una base genética para AxD. Sin embargo, no se conoce el mecanismo por el cual estas variantes producen la enfermedad. Desarrollo: La hipótesis más extendida es que AxD se desarrolla por un mecanismo por ganancia de función debido al incremento de GFAP. Sin embargo, este mecanismo no explica la pérdida mielínica, dado que los modelos experimentales que expresan GFAP normal o mutada no generan alteración mielínica. En la presente revisión se analizan otras posibilidades que permitan justificar dicha alteración, como son alteraciones epigenéticas, inflamatorias, la existencia de células NG2 (+)-GFAP (+) o cambios postraslacionales sobre la GFAP al margen de la mayor expresión. Conclusiones: Las diferentes hipótesis analizadas pueden explicar la alteración de la mielina que aparece en los pacientes y que pueden presentarse asociadas y abren la posibilidad de plantear terapéuticas basadas en estos mecanismos

Introduction: Alexander disease (AxD) is a type of leukodystrophy. Its pathological basis, along with myelin loss, is the appearance of Rosenthal bodies, which are cytoplasmic inclusions in astrocytes. Mutations in the gene coding for GFAP have been identified as a genetic basis for AxD. However, the mechanism by which these variants produce the disease is not understood. Development: The most widespread hypothesis is that AxD develops when a gain of function mutation causes an increase in GFAP. However, this mechanism does not explain myelin loss, given that experimental models in which GFAP expression is normal or mutated do not exhibit myelin disorders. This review analyses other possibilities that may explain this alteration, such as epigenetic or inflammatory alterations, presence of NG2 (+) - GFAP (+) cells, or post-translational modifications in GFAP that are unrelated to increased expression. Conclusions:The different hypotheses analysed here may explain the myelin alteration affecting these patients, and multiple mechanisms may coexist. These theories raise the possibility of designing therapies based on these mechanisms