RESUMEN

Background: Recent studies using magnetic resonance spectroscopy (1H-MRS) indicate that patients with obsessive-compulsive disorder (OCD) present abnormal levels of glutamate (Glu) and gamma aminobutyric acid (GABA) in the frontal and striatal regions of the brain. These abnormalities could be related to the hyperactivation observed in cortico-striatal circuits of patients with OCD. However, most of the previous 1H-MRS studies were not capable of differentiating the signal from metabolites that overlap in the spectrum, such as Glu and glutamine (Gln), and referred to the detected signal as the composite measure-Glx (sum of Glu and Gln). In this study, we used a two-dimensional JPRESS 1H-MRS sequence that allows the discrimination of overlapping metabolites by observing the differences in J-coupling, leading to higher accuracy in the quantification of all metabolites. Our objective was to identify possible alterations in the neurometabolism of OCD, focusing on Glu and GABA, which are key neurotransmitters in the brain that could provide insights into the underlying neurochemistry of a putative excitatory/inhibitory imbalance. Secondary analysis was performed including metabolites such as Gln, creatine (Cr), N-acetylaspartate, glutathione, choline, lactate, and myo-inositol. Methods: Fifty-nine patients with OCD and 42 healthy controls (HCs) underwent 3T 1H-MRS in the ventromedial prefrontal cortex (vmPFC, 30 × 25 × 25 mm3). Metabolites were quantified using ProFit (version 2.0) and Cr as a reference. Furthermore, Glu/GABA and Glu/Gln ratios were calculated. Generalized linear models (GLMs) were conducted using each metabolite as a dependent variable and age, sex, and gray matter fraction (fGM) as confounding factors. GLM analysis was also used to test for associations between clinical symptoms and neurometabolites. Results: The GLM analysis indicated lower levels of Glu/Cr in patients with OCD (z = 2.540; p = 0.011). No other comparisons reached significant differences between groups for all the metabolites studied. No associations between metabolites and clinical symptoms were detected. Conclusions: The decreased Glu/Cr concentrations in the vmPFC of patients with OCD indicate a neurochemical imbalance in the excitatory neurotransmission that could be associated with the neurobiology of the disease and may be relevant for the pathophysiology of OCD.

RESUMEN

The past 20 years have resulted in unprecedented progress in understanding brain energy metabolism and its role in health and disease. In this review, which was initiated at the 14th International Society for Neurochemistry Advanced School, we address the basic concepts of brain energy metabolism and approach the question of why the brain has high energy expenditure. Our review illustrates that the vertebrate brain has a high need for energy because of the high number of neurons and the need to maintain a delicate interplay between energy metabolism, neurotransmission, and plasticity. Disturbances to the energetic balance, to mitochondria quality control or to glia-neuron metabolic interaction may lead to brain circuit malfunction or even severe disorders of the CNS. We cover neuronal energy consumption in neural transmission and basic ('housekeeping') cellular processes. Additionally, we describe the most common (glucose) and alternative sources of energy namely glutamate, lactate, ketone bodies, and medium chain fatty acids. We discuss the multifaceted role of non-neuronal cells in the transport of energy substrates from circulation (pericytes and astrocytes) and in the supply (astrocytes and microglia) and usage of different energy fuels. Finally, we address pathological consequences of disrupted energy homeostasis in the CNS.

Asunto(s)

RESUMEN

Hay algunas enfermedades secundarias a errores innatos del metabolismo que se asocian a trastornos psiquiátricos o síntomas neurológicos menores. La existencia de algunos pacientes con signos únicamente psiquiátricos representa un desafío diagnóstico y terapéutico. El objetivo del presente artículo es describir 6 enfermedades neurometabólicas tratables que se presentan con síntomas psiquiátricos que camuflan su origen orgánico, con el propósito de que se las tome en cuenta en la consulta psiquiátrica. Se describen los trastornos del metabolismo de la homocisteína y del ciclo de la urea, la enfermedad de Wilson, la enfermedad de Niemann-Pick tipo C, la porfiria aguda y la xantomatosis cerebrotendinosa. El análisis de la literatura lleva a proponer una lista de síntomas psiquiátricos asociados con dichas afecciones, que abarcan desde los cambios insidiosos del afecto y el curso del pensamiento hasta síntomas atípicos, como alucinaciones visuales, efectos paradójicos de los medicamentos antipsicóticos y trastornos del comportamiento de niños y adolescentes que conllevan degradación de la autonomía. Asimismo se listan los signos neurológicos más frecuentemente relacionados, como las alteraciones del estado de conciencia, los trastornos de la conducta motora y el equilibro, la catatonia o el déficit cognitivo progresivo. Se hace hincapié en la importancia de considerar la resistencia al tratamiento antipsicótico como una señal importante para sospechar organicidad y la mejoría significativa de la alteración psiquiátrica cuando se instaura un tratamiento eficaz y precoz.

Some diseases secondary to inborn errors of metabolism are associated with psychiatric, disorders or minor neurological symptoms. The existence of some cases with exclusively psychiatric symptoms represents a diagnostic and therapeutic challenge. The aim of this article is to describe seven treatable neurometabolic disorders that should be taken into account in the psychiatric consultation as they manifest with psychiatric symptoms that mask the organic origin of the disorder. Homocysteine metabolism and urea cycle disorders, Wilson's disease, Niemann-Pick disease Type C, acute porphyria and cerebrotendinous xanthomatosis are described. Following an analysis of the literature, a list of psychiatric symptoms associated with these disorders are proposed, ranging from insidious changes in affective state and thought to atypical symptoms such as visual hallucinations, as well as paradoxical effects of antipsychotics or behavioural disorders in children and adolescents associated with loss of autonomy. The most frequently associated neurological signs, such as alterations in the state of consciousness, motor behaviour and balance disorders, catatonia or progressive cognitive deficit are also listed. Emphasis is placed on the importance of considering resistance to antipsychotic treatment as a warning sign to suspect organicity, as well as the significant improvement in psychiatric impairment when effective and early treatment is established.

Asunto(s)

RESUMEN

Inherited neurometabolic disorders represent a growing group of inborn errors of metabolism that present with major neurological symptoms or a complex spectrum of symptoms dominated by central or peripheral nervous system dysfunction. Many neurological presentations may arise from the same metabolic defect, especially in autosomal-recessive inherited disorders. Motor neuron disease (MND), mainly represented by amyotrophic lateral sclerosis, may also result from various inborn errors of metabolism, some of which may represent potentially treatable conditions, thereby emphasizing the importance of recognizing such diseases. The present review discusses the most important neurometabolic disorders presenting with motor neuron (lower and/or upper) dysfunction as the key clinical and neuropathological feature.

Asunto(s)

RESUMEN

Resumen Las enfermedades neurometabólicas constituyen un grupo de patologías poco frecuentes y en notable expansión, de difícil diagnóstico y complicado manejo. Este artículo pretende desarrollar una orientación práctica frente a la sospecha de una enfermedad metabólica, a partir del análisis de la neuroimagen. Es muy importante para el neuropediatra sospecharlas pero siempre en función de los antecedentes , de los signos y síntomas neurológicos (retardo del desarrollo, déficit cognitivo, epilepsia refractaria, distonía, crisis metabólicas o la presencia de signos extraneurológicos inexplicados), de los hallazgos bioquímicos y de la neuroimagen. En muchas ocasiones los hallazgos son totalmente inespecíficos, sin embargo en otras situaciones la neuroimagen, en especial la resonancia magnética craneal (RM), puede ser muy orientadora o simplemente especí ca de una enfermedad metabólica. El examen pormenorizado de la RM valorando el compromiso de la sustancia blanca, de la sustancia gris, de los ganglios basales o del cerebelo podrá orientar hacia un grupo concreto de enfermedades metabólicas. Además con la RM espectroscópica (RME) y con las técnicas de difusión se pueden orientar/diagnosticar algunos errores Innatos del Metabolismo (EIM), seguir la evolución o incluso valorar la respuesta a la terapia.

Abstract Neurometabolic diseases constitute a group of rare diseases and in remarkable expansion, with difficult diagnosis and complicated management. This article aims to develop a practical orientation to the suspicion of a metabolic disease, based on the neuroimaging analysis. Neurological signs and symptoms (developmental delay, cognitive deficit, refractory epilepsy, dystonia, metabolic crises or the presence of unexplained extraneurologic signs) are very important for the neuropediatrician, but always on the basis of their antecedents, biochemical findings and of neuroimaging. In many cases neuroimaging (specially cranial magnetic resonance) (MRI) ndings are totally non-specific, however in other situations the neuroimaging can be very suspicious or simply specific to a metabolic disease. Detailed examination with MRI of white matter, gray matter, basal ganglia, or cerebellum may be directed towards a speci c group of metabolic diseases. In addition to the spectroscopic MRI and di usion techniques, some EIM can be targeted / diagnosed, follow the evolution or even evaluate the response to therapy.

Asunto(s)

RESUMEN

Resumen Las Enfermedades Neurometabólicas (ENM) son trastornos bioquímicos en la estructura y/o función de proteínas, de origen genético, por mutaciones en el ADN, causando un déficit enzimático con acumulación del sustrato o producción de metabolitos anormales. Consideradas enfermedades raras por su escasa incidencia, en su conjunto constituyen un motivo de admisión, consulta y morbimortalidad infantil frecuente. Las formas clínicas de presentación incluyen la forma de "intoxicación", las que afectan el metabolismo energético y las que afectan las moléculas complejas con compromiso de las organelas celulares (lisosomas, peroxisomas). El diagnóstico preciso y oportuno de las ENM es crucial, especialmente para aquellos trastornos que son tratables o manejables, con menor impacto en los pacientes, evitando no solo la muerte sino secuelas irreversibles. El diagnóstico clínico es el primer paso para su abordaje partiendo de la elaboración de una adecuada historia clínica, recolección detallada de antecedentes familiares y personales, considerando la edad de la aparición de los síntomas, siendo el periodo neonatal donde la mayoría debutan. La exploración física completa por aparatos y sistemas con especial énfasis en el examen neurológico, permite solicitar con mayor precisión los exámenes complementarios correspondientes para realizar una aproximación diagnóstica más acertada. El uso de herramientas diagnósticas mediante programas electrónicos, algunos de ellos disponibles gratuitamente como el Programa NeurometPlus ( www.neurometplus.com ), permite alcanzar de forma rápida y efectiva el diagnóstico más probable, así como manejo médico y tratamiento disponible actual.

Abstract Neurometabolic Disorders are conditions caused by alterations in the biochemical structure and function of proteins resulting from changes in DNA, causing a lack or dysfunction of an enzyme leading to an accumulation of a substrate or production of abnormal metabolites. Though considered rare diseases, due to low incidence, together they constitute a frequent cause for pediatric admissions and consultations with significant morbidity and mortality in childhood. Neurometabolic disorders may be classified as disorders of intoxication, energy metabolism, or those disorders affecting complex molecules compromising the cellular organelles (lysosomes and peroxisomes). A timely and precise diagnosis is crucial especially in treatable conditions in order to avoid irreversible sequelae and even death. When encountering a child with a potential neurometabolic disorder, making a clinical diagnosis is the rst step which should include an adequate clinical history, taking into consideration the age of onset of symptoms, and a detailed family history. The neonatal period is when the majority of these conditions make their debut. A complete physical exam with special emphasis on the neurological exam allows for greater precision to help guide the complementary exams that correspond to each condition in order to reach the most probable diagnosis. The use of diagnostic tools including electronic programs and databases, some of which are free of charge such as NeurometPlus ( www.neurometplus.com ), allow a quick and effective diagnosis, along with a guide for medical management and current treatment regimens available.

Asunto(s)

RESUMEN

Pregnancy is a critical period for brain metabolic programming, being affected by individual environment, such as nutrition, stress, and physical exercise. In this context, we previously reported a cerebral antioxidant upregulation and mitochondrial biogenesis in the offspring delivered from exercised mothers, which could provide neuroprotection against neonatal insults. Hypoxia-ischemia (HI) encephalopathy is one of the most studied models of neonatal brain injury; disrupting motor, cognitive, and learning abilities. Physiopathology includes oxidative stress, allied to mitochondria energy production failure, glutamatergic excitotoxicity, and cell death. In this study we evaluated the effect of maternal swimming during pregnancy on offspring׳s brain oxidative status evaluated fourteen days after HI stablishment. Swimming exercise was performed by female adult rats one week before and during pregnancy, in controlled environment. Their offspring was submitted to HI on postnatal day 7, and the brain samples for biochemical assays were obtained in the weaning. Contrary to our expectations, maternal exercise did not prevent the oxidative alterations observed in brain from HI-rats. In a general way, we found a positive modulation in the activities of antioxidant enzymes, measured two weeks after HI, in hippocampus, striatum, and cerebellum of pups delivered from exercised mothers. Reactive species levels were modulated differently in each structure evaluated. Considering the scenery presented, we concluded that HI elicited a neurometabolic adaptation in both brain hemispheres, particularly in hippocampus, parietal cortex, and cerebellum; while striatum appears to be most damaged. The protocol of aerobic maternal exercise was not enough to fully prevent HI-induced brain damages.

Asunto(s)

RESUMEN

In recent years increasing evidence has emerged suggesting that oxidative stress is involved in the pathophysiology of a number of inherited metabolic disorders. However the clinical use of classical antioxidants in these diseases has been poorly evaluated and so far no benefit has been demonstrated. l-Carnitine is an endogenous substance that acts as a carrier for fatty acids across the inner mitochondrial membrane necessary for subsequent beta-oxidation and ATP production. Besides its important role in the metabolism of lipids, l-carnitine is also a potent antioxidant (free radical scavenger) and thus may protect tissues from oxidative damage. This review addresses recent findings obtained from patients with some inherited neurometabolic diseases showing that l-carnitine may be involved in the reduction of oxidative damage observed in these disorders. For some of these diseases, reduced concentrations of l-carnitine may occur due to the combination of this compound to the accumulating toxic metabolites, especially organic acids, or as a result of protein restricted diets. Thus, l-carnitine supplementation may be useful not only to prevent tissue deficiency of this element, but also to avoid oxidative damage secondary to increased production of reactive species in these diseases. Considering the ability of l-carnitine to easily cross the blood-brain barrier, l-carnitine supplementation may also be beneficial in preventing neurological damage derived from oxidative injury. However further studies are required to better explore this potential.

Asunto(s)

RESUMEN

Neurometabolic disorders constitute an expanding and complex field in which it is difficult to diagnose and to acquire a specific education and training. This article tries to develop a practical orientation in the suspicion, clinical exam, biochemical studies and neuroimaging techniques for the detection of inborn errors of metabolism. It is very important for the neuropediatrician to suspect metabolic diseases depending on some of the most frequent unexplained neurological disturbances and symptoms as psychomotor delay, mental retardation, refractory epilepsy, dystonia, metabolic crisis or other extraneurological signs. It is important the diagnosis related to the new emergent therapeutic options, genetic counseling and prenatal diagnosis.

Asunto(s)