[Dilatation of Virchow-Robin perivascular spaces (types III cerebral lacunae): radio-clinical correlations]

Deregulation of the Glymphatic System in Alzheimer's Disease: Genetic and Non-Genetic Factors

Alzheimer's disease (AD) is the most prevalent form of dementia and is characterized by progressive degeneration of brain function. AD gradually affects the parts of the brain that control thoughts, language, behavior and mental function, severely impacting a person's ability to carry out daily activities and ultimately leading to death. The accumulation of extracellular amyloid-β peptide (Aβ) and the aggregation of intracellular hyperphosphorylated tau are the two key pathological hallmarks of AD. AD is a complex condition that involves both non-genetic risk factors (35%) and genetic risk factors (58-79%). The glymphatic system plays an essential role in clearing metabolic waste, transporting tissue fluid, and participating in the immune response. Both non-genetic and genetic risk factors affect the glymphatic system to varying degrees. The main purpose of this review is to summarize the underlying mechanisms involved in the deregulation of the glymphatic system during the progression of AD, especially concerning the diverse contributions of non-genetic and genetic risk factors. In the future, new targets and interventions that modulate these interrelated mechanisms will be beneficial for the prevention and treatment of AD.

Burden of dilated perivascular spaces in patients with moyamoya disease and moyamoya syndrome is related to middle cerebral artery stenosis

Background and objective

The correlation between intracranial large artery disease and cerebral small vessel disease (CSVD) has become a noteworthy issue. Dilated perivascular spaces (dPVS) are an important marker of CSVD, of which cerebral atrophy has been regarded as one of the pathological mechanisms. DPVS has been found to be associated with vascular stenosis in patients with moyamoya disease (MMD), but the underlying mechanism remains unclear. The purpose of our study was to explore the correlation between the middle cerebral artery (MCA) stenosis and dPVS in the centrum semiovale (CSO-dPVS) in patients with MMD/moyamoya syndrome (MMS) and to determine whether brain atrophy plays a mediating role in this relationship.

Methods

A total of 177 patients were enrolled in a single-center MMD/MMS cohort. Images of their 354 cerebral hemispheres were divided into three groups according to dPVS burden: mild (dPVS 0-10), moderate (dPVS 11-20), and severe (dPVS > 20). The correlations among cerebral hemisphere volume, MCA stenosis, and CSO-dPVS were analyzed, adjusting for the confounding factors of age, gender, and hypertension.

Results

After adjustment for age, gender, and hypertension, the degree of MCA stenosis was independently and positively associated with ipsilateral CSO-dPVS burden (standardized coefficient: β = 0.247, P < 0.001). A stratified analysis found that the subgroup with a severe CSO-dPVS burden exhibited a significantly higher risk of severe stenosis of the MCA [p < 0.001, OR = 6.258, 95% CI (2.347, 16.685)]. No significant correlation between CSO-dPVS and ipsilateral hemisphere volume was found (p = 0.055).

Conclusion

In our MMD/MMS cohort, there was a clear correlation between MCA stenosis and CSO-dPVS burden, which may be a direct effect of large vessel stenosis, without a mediating role of brain atrophy.

Controversies and Misconceptions Related to Cerebrospinal Fluid Circulation: A Review of the Literature from the Historical Pioneers' Theories to Current Models

Models of cerebrospinal fluid (CSF) circulation have been mainly proposed in the last century: CSF goes from the ventricles to the subarachnoidal space (SAS), passing through the aqueduct and the foramen of Luschka and Magendie. Indeed, new models, involving the Virchow-Robin space (VRS) and the perivascular space (PVS), have been proposed. We critically reviewed the literature, in order to clarify the “classical” errors and to discuss the “new” models that are evolving currently. Conclusions of past experiments are often not justified, due to lack of reproducibility and methodological issues. On the other hand, investigation on the microanatomy of Virchow-Robin spaces (VRS) and several new experiments showed a potential pathway for a more complex CSF “circulation,” with chaotic and unpredictable flows. It seems reasonable to elaborate a new model of CSF physiology, including new findings and questioning old certainties. However, proved data are still missing and it is hazardous to come to final conclusions. More studies are needed.

Pulsatile and steady components of blood pressure and subclinical cerebrovascular disease: the Northern Manhattan Study

OBJECTIVES

To assess whether pulse pressure (PP) is associated, independently of mean arterial pressure (MAP), with perivascular spaces (PVS), lacunar lesions presumably ischemic (LPI), and white matter hyperintensity volume (WMHV) seen on brain MRI.

METHODS

Participants in the Northern Manhattan Study had their blood pressure (BP) taken during their baseline enrollment visit and again during a visit for a brain MRI a mean of 7 years later. We assessed small and large PVS, lacunar LPI, and WMHV on MRI. We examined the association of SBP, DBP, MAP, and PP at baseline with subclinical markers of cerebrovascular disease using generalized linear models and adjusting for vascular risk factors.

RESULTS

Imaging and BP data were available for 1009 participants (mean age 68 ± 8 years, 60% women, 60% Hispanic). DBP was associated with lacunar LPI and WMHV, whereas SBP was associated with small and large PVS. Using MAP and PP together disclosed that the effect size for PP was greater for large PVS, whereas the effect of MAP was greater for lacunar LPI and WMHV. The effects of DBP were flat or negative at any degree of SBP higher than 120 mmHg for small and large PVS, whereas a positive association was noted for lacunar LPI and WMHV with any DBP increase over any degree of SBP.

CONCLUSION

We report here a segregated association between the pulsatile and steady components of the BP with subclinical markers of cerebrovascular disease. These differential associations may reflect the underlying disease of these biomarkers.

Hydrocephalus due to extreme dilation of Virchow-Robin spaces

Virchow-Robin spaces (VRS) are extensions of the subarachnoid space surrounding perforating blood vessels entering the brain parenchyma. VRS are fluid filled, but almost virtual and only visible on MRI of the brain when dilated. Such dilations are commonly asymptomatic. In rare cases, extreme dilations can be observed; the clinical repercussions of which remain unclear. We report the case of a patient presenting symptoms of normal pressure hydrocephalus due to extreme VRS mesencephalon dilations.

Dilatation of Virchow-Robin spaces in children hospitalized at pediatric neurology department

BACKGROUND AND PURPOSE

Dilated Virchow-Robin spaces (dVRs) have been revealed by magnetic resonance imaging (MRI) in patients with various neurological disorders. However, their etiology and clinical importance have not been discovered yet. The aim of the study was to estimate dVRs occurrence in hospitalized children and determine dVRs localization and their association with different nervous system diseases.

MATERIAL AND METHODS

Contrast-enhanced brain MRI examinations with the use of 1.5T GE device were performed in children with different diseases of nervous system, who were hospitalized at Pediatric Neurology Department, Chair of Children and Adolescent Neurology, Jagiellonian University in the years 2010-2011. The mean age of examined children was 11.58 years, and the studied group included 27 boys and 26 girls.

RESULTS

Within two years, MRI examinations of the brain were performed in 1348 children and dVRs were found in 53 of them (3.93%). Among children with dVRs, 15 were diagnosed with headache (28.3%) and 18 with epilepsy (33.96%). Other diagnoses were less frequent and occurred in 37.7%. Generalized dVRs and those localized in the subcortical nuclei were most frequently found.

CONCLUSIONS

Higher incidence of dVRs was found in children with headache and epilepsy. No association was found between localization of dVRs and symptomatology of different nervous system diseases except for large dVRs probably due to the pressure on the surrounding tissues.

Adult symptomatic and growing arachnoid cyst successfully treated by ventriculocystostomy: a new insight on adult arachnoid cyst history

BACKGROUND

Adult arachnoid cysts are known to be stable and asymptomatic but their history remains undefined.

CASE DESCRIPTION

The authors report the case of an 81-year-old woman with progressive hemiplegia and aphasia. CT scan revealed a voluminous left frontotemporal arachnoid cyst with a major mass effect on the midline and contralateral blocked hydrocephalus. Endoscopic ventriculocystostomy was performed with a spectacular neurological improvement.

DISCUSSION AND CONCLUSIONS

Symptomatic adult arachnoid cysts are extremely rare. To our knowledge, no similar clinical case of a growing arachnoid cyst in elderly patients has yet been reported in the literature. The mechanisms of cyst enlargement and decompensation still remain undefined and debated. The possibility of adult arachnoid cyst growth has to be considered in clinical practice. Endoscopic ventriculocystostomy is as effective as in paediatric cases.

[Symptomatic giant Virchow-Robin spaces]

INTRODUCTION

Perivascular spaces, known as Virchow-Robin spaces (VRS), may become massively enlarged but are usually an incidental finding. However, a few reports on patients with unusually large VRS have mentioned association with neurological symptoms. We report a series of three symptomatic patients with extremely wide Virchow-Robin spaces documented on brain magnetic resonance imaging (MRI).

METHODS

We retrospectively analyzed the medical records and brain MRI of three symptomatic patients, who had been diagnosed with VRS widening.

CASE REPORTS

In all three patients, the unusual widening of the VRS was located within the subcortical white matter with asymmetric distribution. Their neurological symptoms were epilepsy and neurological deficits which correlated well with the lesions seen on the MRI. Two patients had associated white matter hyperintensities: in the first case associated gliosis and in the second case, with vascular leukoencephalopathy.

CONCLUSIONS

Enlarged symptomatic VRS are rare. The underlying pathophysiological mechanisms remain uncertain. We report three cases with symptomatic giant dilatation of the Virchow-Robin spaces.

Giant Dilatations of Virchow-Robin Spaces in the Midbrain

Virchow-Robin spaces are lesions often seen in the brain parenchyma but their etiopathogenesis remains unsettled. Giant Virchow-Robin spaces placed in the midbrain are extremely rare. We describe three patients with a diagnosis of giant Virchow-Robin spaces in the midbrain, and their clinical and radiologic findings. We reviewed the literature in terms of the etiopathology, anatomic and radiologic appearance and differential diagnosis of the giant Virchow-Robin spaces. The diagnostic role of the high Tesla magnetic resonance devices and new sequences techniques such as three dimensional isotropic acquisition and diffusion tensor imaging were also evaluated in this case series.

Lobar Dementia due to Extreme Widening of Virchow-Robin Spaces in One Hemisphere

Widened perivascular spaces known as Virchow-Robin spaces (VRS) are often seen on MRI and are usually incidental findings. It is unclear if enlarged VRS can be associated with neurological deficits. In this report, we describe a case of lobar dementia associated with unusual VRS widening in one cerebral hemisphere. A 77-year-old woman, seen at a memory clinic, presented with progressive cognitive decline, left hemianopsia, and mild pyramidal signs on the left side. On MRI, unusually wide VRS were visible, predominantly in the right centrum semiovale and the right temporo-occipital white matter. The clinical syndrome was consistent with the extent and location of the abnormally dilated VRS. The high MR signal in white matter bridges between the VRS suggested parenchymal damage, possibly representing gliotic white matter. No evidence for another etiology was found on cerebral MRI and rCBF SPECT. As a conclusion, enlarged VRS in one cerebral hemisphere may be associated with cognitive change and neurological deficits.

MR imaging of midbrain pathologies

The spectrum of pathologic processes affecting the midbrain features some differences to other brain areas. The midbrain is exposed to traumatic alterations due to its position between the tentorial edges, and some neurodegenerative and metabolic-toxic diseases may typically involve the midbrain. Isolated midbrain ischemia is rare, whereas the midbrain is typically part of the "top of the basilar" syndrome. Primary midbrain tumors are also infrequent and often show a benign clinical course. Apart from multiple sclerosis other inflammatory autoimmune processes and some infectious agents predominantly affect the brainstem including the midbrain. This review discusses the different pathologic processes of the midbrain, i.e., infarction, hemorrhage and trauma, inflammation, toxic and metabolic diseases, neurodegeneration, neoplastic diseases, as well as pathologies typically involving the perimesencephalic cisterns.

Perivascular space and neurological disorders

Perivascular space (PVS) is a crevice between two slices of cerebral pia maters, filled with tissue fluid, which be formed by pia mater emboling in the surrounding of cerebral perforating branch (excluding micrangium). Normal PVS (diameter < 2 mm) can be found in almost all healthy adults; however enlarged PVS (diameter > 2 mm) has correlation with neurological disorders probably. The article reviews the formation mechanism, imageology characteristics and the relation with neurological disorders of PVS, which is beneficial to the research of some neurological disorders etiopathogenesis and treatment.

[Giant cystic widening of Virchow-Robin spaces, case report]

INTRODUCTION

Virchow-Robin spaces are very well-known anatomical and radiological entities. However, the observation of giant cystic widening of Virchow-Robin spaces is anecdotic. We report herein the case of a patient presenting with giant cystic widening of Virchow-Robin spaces located in both cerebral hemispheres.

OBSERVATION

A 26-year-old female presented with numbness of left arm and then, of both arms. CT scan showed many hypodensities located in the two hemispheres. Neurologic examination was normal. MR imaging allowed the diagnosis of giant cystic widening Virchow-Robin spaces in T2, T2*, T1 gadolinium and Flair weighted images. Neuropsychological investigations were normal.

CONCLUSION

Giant cystic widening of Virchow-Robin spaces are extremely rare entities. MR imaging helps the diagnosis. Only extreme dilatation of Virchow-Robin perivascular spaces close to ventricular system must be watched and treated in case of an obstructive hydrocephalus risk. When located in cerebral hemispheres, these dilatations are mostly asymptomatic and must not be confused with a cystic tumoral disease.