Sistema glinfático: aspectos anatómicos, fisiológicos e implicaciones clínicas

Introducción: El sistema glinfático comprende el conjunto de rutas perivasculares tanto arteriales como venosas que se encuentran en estrecha asociación con células astrogliales y que permiten la interacción entre el líquido cefalorraquídeo (LCR) y el líquido intersticial cerebral (LIC), para llevar a cabo procesos como la depuración de los metabolitos de desecho celular, o la distribución de nutrientes, así como contribuir al metabolismo cerebral local, la transmisión de volumen y la señalización paracrina cerebral. Contenidos: Este artículo busca profundizar en los conceptos anatómicos y fisiológicos, hasta el momento descritos, sobre este sistema macroscópico de transporte. Se realiza una búsqueda bibliográfica de revisiones y estudios experimentales sobre la anatomía, la fisiología y las implicaciones fisiopatológicas del sistema glinfático. Conclusiones: La identificación anatómica y funcional del sistema glinfático ha ampliado el conocimiento sobre la regulación del metabolismo cerebral en cuanto a distribución de nutrientes y cascadas de señalización celular. Al establecer una interacción entre el espacio subaracnoideo subyacente y el espacio intersticial cerebral, el sistema glinfático surge como uno de los mecanismos protagonistas de la homeostasis cerebral. La disfunción de esta vía hace parte de los mecanismos fisiopatológicos de múltiples trastornos neurológicos, ya sea por la acumulación de macromoléculas, como ocurre en la enfermedad de Alzheimer, o por la reducción del drenaje de sustancias químicas y citocinas proinflamatorias en patologías como la migraña o el trauma craneoencefálico.

Introduction: The glympathic system comprises the set of perivascular routes, arterials or venous, that are found in close relationship with astroglial cells and allow interaction between the cerebrospinal fluid (CSF) and the interstitial brain fluid (ISF), to carry processes like cell-wasting metabolites depuration, nutrients distribution, as well as make a contribution in the local brain metabolism, volumen transmition and brain paracrine signaling. Contents: This article seeks to deepen in the anatomical and physiological concepts, so far described, about this macroscopic transport system. A bibliographic search of reviews and experimental studies on the anatomy, physiology and pathophysiological implications of the glymphatic system is carried out. Conclusions: Anatomical and functional identification of glympathic system has broaden the knowledge about regulation of brain metabolism on the nutrients distribution and cell signaling cascades. When setting an interaction between the subarachnoid space and the brain interstitial space, the glymphatic system arise as one of the leading mechanisms of brain homeostasis. Disfunction of this pathway makes part of the patophysiological mechanisms of multiple neurological disease, either be by collection of macromolecules as in Alzheimer's disease, or by the reduction of inflammatory cytokines and chemical substances drainage as in migraine or traumatic brain injury (TBI).

Study on imaging features of asymptomatic cerebral small vessel disease and related factors in the elderly population / 中华老年医学杂志

Objective:To investigate the incidence, neuroimaging features, and related factors for asymptomatic cerebral small vessel disease(CSVD)in the elderly population.Methods:A total of 201 elderly people with no neurological disease history who had undergone brain magnetic resonance imaging(MRI)examination from October 2019 to August 2020 were enrolled.We calculated the total CSVD score for each participant based on lacunar infarcts(LIs), white matter hyperintensities(WMH), enlarged perivascular spaces(EPVS), and cerebral microbleeds(CMBs)(0-4 points).CSVD neuroimaging features and the correlation between CSVD markers and clinical variables were analyzed.Results:In this study, 133 cases(66.2%)showed MRI features consistent with CSVD.Of whom, LIs were present in 44(21.9%), high-grade PVWMH in 88(43.8%), high-grade DWMH in 30(14.9%), basal ganglia EPVS in 61(30.3%), and CMBs in 92(45.8%).Total CSVD burden score( OR=1.876, 95% CI: 1.045-3.364, χ2=4.441, P=0.035), PVWMH( OR=2.821, 95% CI: 1.517-5.244, χ2=10.752, P=0.001), DWMH( OR=2.130, 95% CI: 1.108-4.092, χ2=5.145, P=0.023), and EPVS( OR=3.258, 95% CI: 1.675-6.334, χ2=12.129, P=0.000)were associated with hypertension.Total CSVD burden score, PVWMH, DWMH, EPVS, and CMB were correlated with increasing age( P<0.05).LIs was positively correlated with PVWMH( b=0.231, P=0.001), DWMH( b=0.247, P=0.000)and EPVS( b=0.215, P=0.001).There was a positive relationship between PVWMH and DWMH( b=0.546, P=0.000)as well as EPVS( b=0.388, P=0.000).DWMH was also positively correlated with EPVS( b=0.357, P=0.000)and CMB( b=0.177, P=0.009). Conclusions:The incidence of asymptomatic CSVD is high in the elderly population.The total CSVD score is a useful measure to evaluate asymptomatic cerebral small vessel disease in the elderly population.Neuroimaging features of asymptomatic CSVD are mainly correlated with age and hypertension.

Correlation between enlarged perivascular spaces and the imaging markers of cerebrovascular disease in patients with ischemic stroke / 中华行为医学与脑科学杂志

Objective:To explore the correlation between enlarged perivascular spaces and other imaging markers of cerebrovascular disease in patients with ischemic stroke.Methods:Totally 287 patients with ischemic stroke hospitalized in neurology department from January 2018 to January 2019 were selected. According to the severity of EPVS in different parts of the brain, the correlations between the severity of EPVS in different parts of the brain and cerebral microbleeds (CMBs), white matter hyperintensity (WMH), lacunar infarcts (LIs) were analyzed. SPSS 22.0 software was used for analysis. Chi-square test, independent sample t-test, rank-sum test and non parametric Mann-Whitney U test were used for group comparison, and Logistic regression analysis was used for multivariate analysis. Results:EPVS was common and severe in patients with ischemic stroke. Periventricular white matter hyperintensity(PWMH)( β=1.604, P<0.001, OR=4.971, 95% CI=2.015-12.263), CMBs ( β=1.224, P=0.018, OR=3.339, 95% CI=1.232-9.383) and LIs ( β=0.626, P=0.047, OR=1.871, 95% CI=1.009-3.470) were independent risk factors for BG-EPVS. PWMH ( r=0.614), DWMH ( r=0.622), LIs ( r=0.532) were positively correlated with the severity of BG-EPVS (all P<0.01). Conclusion:The imaging makers of CSVD are related to BG-EPVS, which can affect the severity of brain BG-EPVS in patients with ischemic stroke.

Giant perivascular spaces: two case reports

Giant perivascular spaces or Virchow-Robin spaces (VRSs) are uniquely inherent developmental malformation and are generally lined by ependymal or leptomeningeal cells. The cerebral hemispheres with VRSs present multiple cysts of curvilinear, round, oval, or layered configuration, which have the same signal intensity as the cerebrospinal fluid (CSF) and represent extremely dilated VRSs. The cortex became extremely thin with a well-defined margin. Herein, we report two cases of true giant perivascular spaces and present a review of pertinent literature. A patient has multiple cysts in the unilateral and bilateral and has polycystic liver. The clinical presentation, image logical features, and diagnosis are discussed.

Relationship between chronic renal injury and white matter hypertensity, enlarged perivascular spaces in elderly patients / 临床神经病学杂志

Objective To study the relationship between chronic renal injury and white matter hypertensity (WMH), enlarged perivascular spaces (EPVS) in elderly patients.Methods A total of 133 inpatients from 2015 to 2016 without clinical histories of stroke underwent brain MRI scan were enrolled.The degree of WMH and EPVS were evaluated according to Flair and T 2 MRI, respectively.Clinical characteristics including disease history , glomerular filtration rate ( eGFR), urine albumine／creatine ratio ( UACR ) and so on were compared between different degrees of WMH or EPVS.A logistic regression analysis was applied for further analysis.Results Compared with WMH scoring 0 -1 group, eGFR of WMH scoring 2 -3 group was significantly decreased , while UACR was significantly increased ( all P＜0.001).Compared with EPVS scoring 0 -1 group, eGFR of EPVS scoring 2-3 group was significantly decreased , while UACR was significantly increased (all P＜0.001).Logistic regression analysis showed that low eGFR and high UACR were independent risk factors for WMH and EPVS (all P＜0.05).Conclusion Chronic renal injury could be the independent risk factor of higher degree of WMH and EPVS , which would be potential for clinical use.

Enlarged perivascular spaces and vascular cognitive impairment / 国际脑血管病杂志

As an imaging manifestation of cerebral small vascular disease,the relationship between enlarged perivascular spaces (EPVS) and cognitive impairment has attracted much attention.Clinical studies have shown that EPVS may be present in the general population and in patients with cognitive impairment caused by neurodegenerative or cerebrovascular diseases.Further studies have showed that EPVS may be an independent risk factor for cognitive impairment.This article reviews the pathogenesis of cognitive impairment in individuals with EPVS.

Total Cerebral Small-Vessel Disease Score is Associated with Mortality during Follow-Up after Acute Ischemic Stroke

BACKGROUND AND PURPOSE: The recently developed total cerebral small-vessel disease (CSVD) score might appropriately reflect the total burden or severity of CSVD. We investigated whether the total CSVD score is associated with long-term outcomes during follow-up in patients with acute ischemic stroke. METHODS: In total, 1,096 consecutive patients with acute ischemic stroke who underwent brain magnetic resonance imaging were enrolled. We calculated the total CSVD score for each patient after determining the burden of cerebral microbleeds (CMBs), high-grade white-matter hyperintensities (HWHs), high-grade perivascular spaces (HPVSs), and asymptomatic lacunar infarctions (ALIs). We recorded the date and cause of death for all of the patients using data from the Korean National Statistical Office. We compared the long-term mortality rate with the total CSVD score using Cox proportional-hazards models. RESULTS: CMBs were found in 26.8% of the subjects (294/1,096), HWHs in 16.4% (180/1,096), HPVSs in 19.3% (211/1,096), and ALIs in 38.0% (416/1,096). After adjusting for age, sex, and variables that were significant at p<0.1 in the univariate analysis, the total CSVD score was independently associated with long-term death from all causes [hazard ratio (HR)=1.18 per point, 95% confidence interval (CI)=1.07–1.30], ischemic stroke (HR=1.20 per point, 95% CI=1.01–1.42), and hemorrhagic stroke (HR=2.05 per point, 95% CI=1.30–3.22), but not with fatal cardiovascular events (HR=1.17 per point, 95% CI=0.82–1.67). CONCLUSIONS: The total CSVD score is a potential imaging biomarker for predicting mortality during follow-up in patients with acute ischemic stroke.

Alargamento unilateral dos espaços perivasculares observados à ressonância magnética em um caso de hipomelanose de Ito: qual o valor deste achado? / The unilateral enlargement of the perivascular spaces on magnetic resonance imaging in a case of hypomelanosis of Ito: which the value of this finding?

Hipomelanose de Ito é uma síndrome neurocutânea rara, ligada ao cromossomo X, de caráter dominante, caracterizada por manchas hipopigmentadas seguindo as linhas de Blaschko, dispostasem espirais e estrias, que estão presentes ao nascimento ou surgem nos primeiros meses de vida.O envolvimento cerebral é frequente e representado por retardo mental e convulsões. Anormalidadesmusculoesqueléticas, dentárias, cardíacas, gastrintestinais ou urinárias podem estar presentes.A avaliação por imagem é normal em até 25% dos casos, porém o alargamento dos espaçosperivasculares, dentre outras apresentações de imagem, pode estar presente. Assim sendo, o diagnóstico diferencial com patologias tumorais e não-tumorais deve ser estabelecido.

Hypomelanosis of Ito is a rare neurocutaneous syndrome, X-linked,dominant, characterized by hypopigmented lesions of skin alongthe Blaschko lines. Skin lesions usually are present at birth orappear early in life. The cerebral involvement is frequent and represented by mental retardation and seizures. Skeletal Muscleabnormalities, dental, cardiac, gastrointestinal or urinary may bepresent. The imaging evaluation is normal up to 25% of the casesbut the enlargement of perivascular spaces, among other imagespresentations, may be present, thus the differential diagnosis oftumor and non-tumor, should be established.