Virchow-Robin spaces at MR imaging

Magnetic resonance imaging in fungal infections of the brain

An invasive fungal infection is a rare disease that can occur in otherwise healthy individuals. Fungi themselves are universal, and they are overall harmless organisms that cause at most a self-limiting disease in the general population. Immunocompromised individuals, whether iatrogenically, genetically, or acquired, present a group who are especially susceptible to a life-threatening disease from a normally innocuous pathogen. Fungi are normally inhaled and are cleared by pulmonary defense mechanisms in immunocompetent hosts. Invasion begins when these mechanisms fail in depressed immunity. Through bypassing of the pulmonary immune system, fungi can spread hematogenously. Fungal infections of the central nervous system are the most common extrapulmonary manifestation after fungal inhalation. Other risk factors of fungemia include prolonged indwelling catheters, maxillofacial infections, uncontrolled diabetes mellitus, systemic antibiotics, implanted neurosurgical devices, and intravenous drug abuse. Thus, other than direct inoculation via surgical complications or open trauma, central nervous system fungal infections are almost never primary.

MRI-visible perivascular spaces: relationship to cognition and small vessel disease MRI markers in ischaemic stroke and TIA

BACKGROUND

MRI-visible perivascular spaces (PVS) are potential neuroimaging markers of cerebral small vessel disease, but their functional significance and mechanisms remain uncertain. We investigated the association between PVS and cognitive impairment, and other MRI markers of small vessel disease, in a patient cohort of ischaemic stroke/transient ischaemic attack (TIA) referrals.

METHODS

Data were collected from a prospective observational database. Standardised detailed neuropsychological testing was performed. A validated visual rating scale on T2-weighted MRI was used to categorise PVS severity; validated scales were used to assess white matter hyperintensities (WMH), cerebral microbleeds (CMB) and lacunes.

RESULTS

We included 246 patients (45.1% female, mean age 62 years). No significant association between PVS severity grade in any brain region and impairment in any cognitive domain was identified. In multivariable analysis, WMH and hypertension (but not age) were independently associated with basal ganglia PVS severity (OR: 1.27; p<0.0001 and OR: 4.89; p=0.013, respectively). Increasing PVS severity in the basal ganglia was associated with lacunar stroke subtype (p<0.0001). Age and hypertension (but not WMH or lacunar stroke subtype) were independently associated with centrum semiovale PVS severity (OR: 1.19; p=0.013 and OR: 3.71; p=0.007, respectively).

CONCLUSIONS

PVS do not have an independent association with cognitive impairment in patients with ischaemic stroke or TIA. The associations with clinical-radiological factors are consistent with the hypothesis that PVS reflect cerebral small vessel disease; the different associations for basal ganglia and centrum semiovale PVS might indicate different underlying small vessel arteriopathies according to PVS anatomical distribution, but this requires further study.

Spontaneous regression and recurrence of a tumefactive perivascular space

Perivascular spaces can occasionally appear mass-like (tumefactive or giant perivascular space), and can be associated with clinical symptoms. Spontaneous regression of a tumefactive perivascular space is a very rare phenomenon with only two reported cases in the English medical literature. Spontaneous regression of a tumefactive perivascular space along with resolution of clinical symptoms, followed by spontaneous recurrence associated with symptom recurrence is an extremely rare occurrence, which to the best of our knowledge, has not been reported in the medical literature. We describe a case of spontaneous regression of a tumefactive perivascular space, three years after its initial detection, followed by spontaneous recurrence after two years.

Can Isolated Enlarged Virchow-Robin Spaces Influence the Clinical Manifestations of Parkinson's Disease?

Dilated Virchow-Robin (VR) spaces are usually not considered to be symptomatic. We present three cases presenting with atypical clinical features, which otherwise had clinical/imaging findings consistent with idiopathic Parkinson's disease. In all cases, an isolated large VR space in the basal ganglia contralateral to the side of symptom onset was observed. We propose that the atypical features could be associated with the mass effect of a significantly enlarged VR space, which would cause a dysfunction downstream from the presynaptic nigrostriatal dopaminergic system.

Is there a connection between perivascular space and subarachnoid space?

Perivascular spaces (PVSs) surrounding the walls of arteries, arterioles, and venules do not directly communicate with subarachnoid spaces. There are a few reports exhibiting subarachnoid hemorrhage (SAH) and intracerebral hematomas extending to the PVSs by leakage of the leptomeninges that surround arteries. In this report, we present 4 patients of whom 3 had SAH extending into the PVSs in the bilateral basal ganglia and 1 had extension of contrast medium to the PVSs after injection of the contrast medium into the lumbar subarachnoid space. The hemorrhage extending to the PVSs in our 3 patients with SAH could be explained by leakage of the leptomeninges surrounding the arteries. However, how the contrast medium extends to the PVSs is not clear. We think that, although speculative, incomplete or complete defect at the leptomeninges surrounding the arteries resulting in direct continuity between the subarachnoid space and the PVS allows that blood or contrast media to extend to the PVSs.

Mucopolysaccharidoses type I and II: new neuroimaging findings in the cerebellum

BACKGROUND

The neuroimaging literature on mucopolysaccharidoses (MPS) is focusing mostly on supratentorial findings. Our study aims to extend the spectrum of neuroimaging findings in patients with MPS focusing on the cerebellum.

METHODS

Twelve patients were included (7 MPS type I and 5 MPS type II). The median age at last MRI was 9.9 years (mean age 10.1 years, range 1.8-28.8 years). All available brain MR images were retrospectively evaluated for infratentorial and supratentorial abnormalities with semiquantitative analysis and qualitative evaluation.

RESULTS

Infratentorial findings included enlarged perivascular spaces (PVS) in the cerebellum in 7/12, mega cisterna magna in 3/12 and macrocerebellum in 2/12 patients. Enlarged cerebellar PVS developed later than those in the supratentorial brain and showed mild changes in size over time. The macrocerebellum developed progressively and seems to be caused by a thickening of the cortical cerebellar gray matter. Enlarged PVS in the brain stem were found in 10/12 patients. Supratentorial findings included enlarged PVS in all patients. Ventriculomegaly and white matter signal abnormalities were noted in 8/12, cerebral atrophy in 7/12 patients.

CONCLUSION

Involvement of the posterior fossa structures in MPS I and II is not uncommon. Our study revealed two neuroimaging findings that have not been previously described in MPS: enlarged PVS in the cerebellum and a macrocerebellum. The pathogenesis and clinical significance of these new findings remain unclear and should be assessed in a larger cohort of patients.

Illustrated Atlas of Post-AF Ablation Cerebral Abnormalities

Atrial fibrillation (AF) is one of the most common cardiac arrhythmias and relates to high morbidity and mortality due to thromboembolic events, especially ischemic stroke. During the last 15 years, transcatheter ablation has emerged as an effective therapeutic option to treat AF but carries a risk of possible complications. The occurrence of cerebrovascular accidents, both symptomatic and silent, is one of the most frequent and severe. Transcatheter AF ablation entails a relevant risk of silent cerebral ischemia detected by means of magnetic resonance imaging, and many efforts have been directed to improve the safety of this procedure.

Intracerebral hematoma extends via perivascular spaces and perineurium

Intracerebral hemorrhage (ICH) is a devastating disorder associated with high morbidity and mortality. ICH results in the formation of hematoma that affects not only the primary site of injury but also the remote regions. In fact, hematoma can extend via perivascular spaces (also called Virchow-Robin spaces, VRS) and perineurium in an animal model of ICH. In the present study, we used magnetic resonance imaging (MRI) with susceptibility-weighted imaging (SWI) to investigate the characteristics of the perivascular and perineural extensions of hematomas in patients with ICH. A total of 20 ICH patients without secondary subarachnoid and secondary intraventricular hemorrhages were recruited. Brain MRI scans, including SWI, T1, and T2-weighted images, were performed between 17 h to 7 days after the onset of ICH. MRI with SWI revealed that paramagnetic substances spread along the VRS or the perineurium. Such distribution could cause the formation of cerebral microbleeds (CMBs). However, the distribution of remote hemorrhagic lesions varied, depending on the size and location of the original hematoma. The unenhanced CT scans of the 20 patients did not show any hyperdensity around the blood vessels and nerve tracts outside the hematoma. These results indicate the perivascular and perineural extensions of hematomas in patients with ICH, which is formed by the leakage of the original hematoma via the VRS or perineurium. We also provide a new explanation for the series of pathological processes involved in ICH, including the remote effects of hematoma and the formation of CMBs in patients with ICH.

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.

[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.

Neuroimaging standards for research into small vessel disease and its contribution to ageing and neurodegeneration

Cerebral small vessel disease (SVD) is a common accompaniment of ageing. Features seen on neuroimaging include recent small subcortical infarcts, lacunes, white matter hyperintensities, perivascular spaces, microbleeds, and brain atrophy. SVD can present as a stroke or cognitive decline, or can have few or no symptoms. SVD frequently coexists with neurodegenerative disease, and can exacerbate cognitive deficits, physical disabilities, and other symptoms of neurodegeneration. Terminology and definitions for imaging the features of SVD vary widely, which is also true for protocols for image acquisition and image analysis. This lack of consistency hampers progress in identifying the contribution of SVD to the pathophysiology and clinical features of common neurodegenerative diseases. We are an international working group from the Centres of Excellence in Neurodegeneration. We completed a structured process to develop definitions and imaging standards for markers and consequences of SVD. We aimed to achieve the following: first, to provide a common advisory about terms and definitions for features visible on MRI; second, to suggest minimum standards for image acquisition and analysis; third, to agree on standards for scientific reporting of changes related to SVD on neuroimaging; and fourth, to review emerging imaging methods for detection and quantification of preclinical manifestations of SVD. Our findings and recommendations apply to research studies, and can be used in the clinical setting to standardise image interpretation, acquisition, and reporting. This Position Paper summarises the main outcomes of this international effort to provide the STandards for ReportIng Vascular changes on nEuroimaging (STRIVE).

Perivascular spaces are associated with atherosclerosis: an insight from the Northern Manhattan Study

BACKGROUND AND PURPOSE

Perivascular spaces are potential spaces found between brain blood vessels and surrounding leptomeninges that have been associated with cardiovascular risk factors and dementia, but less is known about their relationship to atherosclerosis. We tested the hypothesis that perivascular spaces are associated with atherosclerosis.

MATERIALS AND METHODS

Participants from the Northern Manhattan Study who remained stroke-free were invited to participate in an MR imaging substudy. Parenchymal hypointensities of <3 mm identified on brain axial T1-weighted MR imaging were scored as perivascular spaces. A semiquantitative score was created to express the degree of brain involvement. Generalized linear models were used to assess statistical associations with carotid plaque as a surrogate marker of atherosclerosis.

RESULTS

The studied sample included 706 participants (mean age, 72.6 ± 8.0 years; 60% women, 61% Hispanic, 68% with hypertension, 19% with diabetes, and 57% with high cholesterol). The perivascular spaces score ranged from 0 to 19 with 52% of the sample having a perivascular spaces score of ≤4. In unadjusted analysis, perivascular spaces were associated with age (β = 0.01 per year, P = < .001), non-Hispanic black race-ethnicity (β = 0.16, P = .02), hypertension (β = 0.24, P = < .001), and carotid plaque (β = 0.22, P < .001). In multivariable analysis, only age (β = 0.01, P = .02), hypertension (β = 0.17, P = .01), and carotid plaque (β = 0.22, P = < .001) remained independently associated with perivascular spaces.

CONCLUSIONS

Perivascular spaces were more frequently found in older participants, in those with hypertension, and in the presence of carotid plaque. These results suggest that mechanisms leading to atherosclerosis might also lead to an increased number of perivascular spaces. These results need confirmation in prospective studies.

Patients profiling for Botox® (onabotulinum toxin A) treatment for migraine: a look at white matter lesions in the MRI as a potential marker

Background

To evaluate if white matter lesions (WML) on MRI can be a potential marker for onabotulinum toxin A (Botox®) treatment success in migraine, given the limited response rate and high costs per treatment.

Methods

Retrospective data base and MRI analysis of 529 migraineurs who received Botox® between 2002 and 2009. Responders were defined as patients who underwent three or more treatments, whereas non-responders had only one or two treatments. MRIs were analysed on axial T2 and coronar FLAIR (fluid attenuated inversion recovery) sequences for the presence of WML. Statistical analysis was done with the Chi-Square-Test and the Mann–Whitney-U-Test.

Results

Of 529 Botox® treated migraineurs, 111 patients had a MRI. Of these 111 patients, 47 were responders, 64 non-responders to Botox®. Response rate to Botox® in migraineurs with WML was 55.3%, in migraineurs without WML 44.7%. In the investigated items “age”, “age at onset”, “gender”, “attack duration”, “frequency”, “aura”, “WML”, “size of WML”, we found no statistical significant difference between the two groups. 55% of the responders and 50% of the non-responders showed WML. All WML were located supratentorially, anteriorly, mostly of small size (3–5 mm).

Conclusion

WML on MRIs cannot serve as a marker to predict a positive response to Botox®.

Enlarged perivascular spaces and cerebral small vessel disease

Background and aims

Enlarged perivascular spaces (also known as Virchow–Robin spaces) on T2-weighted brain magnetic resonance imaging are common, but their etiology, and specificity to small vessel as opposed to general cerebrovascular disease or ageing, is unclear. We tested the association between enlarged perivascular spaces and ischemic stroke subtype, other markers of small vessel disease, and common vascular risk factors.

Methods

We prospectively recruited patients with acute stroke, diagnosed and subtyped by a stroke physician using clinical features and brain magnetic resonance imaging. A neuroradiologist rated basal ganglia and centrum semiovale enlarged perivascular spaces on a five-point scale, white matter lesions, recent and old infarcts, and cerebral atrophy. We assessed associations between basal ganglia-, centrum semiovale- and total (combined basal ganglia and centrum semiovale) enlarged perivascular spaces, stroke subtype, white matter lesions, atrophy, and vascular risk factors.

Results

Among 298 patients (mean age 68 years), after adjusting for vascular risk factors and white matter lesions, basal ganglia–enlarged perivascular spaces were associated with increasing age (P = 0·001), centrum semiovale–enlarged perivascular spaces (P < 0·001), cerebral atrophy (P = 0·03), and lacunar stroke subtype (P = 0·04). Centrum semiovale–enlarged perivascular spaces were associated mainly with basal ganglia–enlarged perivascular spaces. Total enlarged perivascular spaces were associated with increasing age (P = 0·01), deep white matter lesions (P = 0·005), and previous stroke (P = 0·006).

Conclusions

Enlarged perivascular spaces are associated with age, lacunar stroke subtype and white matter lesions and should be considered as another magnetic resonance imaging marker of cerebral small vessel disease. Further evaluation of enlarged perivascular spaces in studies of ageing, stroke, and dementia is needed to determine their pathophysiological importance.

MRI white matter lesions in pediatric migraine

OBJECTIVES

Studies have reported an association between migraine and white matter hyperintensities on T2-weighted brain magnetic resonance imaging (MRI) in adults. The aim of the present study was to evaluate white matter MRI brain findings in pediatric patients with migraine.

METHODS

The medical files and imaging scans of all 194 patients who underwent brain MRI at the headache clinic of a tertiary medical center in 2008-2011 were reviewed.

RESULTS

Mean age was 10.9 ± 3.5 years. Migraine was diagnosed in 131 patients and other disorders in 63. In the migraine group, findings on physical and laboratory examinations were within normal range. White matter lesions were identified on MRI scan in 14 children with migraine (10.6%) and none of the children with other disorders ( P  = 0.006). In 13/14 patients, the lesions were focal with a variable distribution; in the remaining patient, confluent periventricular hyperintensities were documented.

CONCLUSIONS

In a headache clinic of a tertiary pediatric medical center, white matter lesions are found in about 10% of pediatric patients with migraine.

Trigeminal neuralgia secondary to giant Virchow-Robin spaces: a case report with neuroimaging

Virchow-Robin spaces are pial-lined, interstitial, fluid-filled structures that accompany penetrating arteries and arterioles as they enter the cerebral substance. Occasionally they may enlarge and become giant Virchow-Robin spaces (GVRS) and produce mass effect. Various neurological symptoms have been described in association with GVRS, however, trigeminal neuralgia has not yet been reported in this context. We present a case of trigeminal neuralgia secondary to dorsal pontine giant Virchow-Robin spaces (GVRS) and highlight the diagnostic radiologic features. Routine 1.5 T MRI sequences were sufficient to diagnose the GVRS and a diffusion tensor imaging (DTI) study revealed distortion of the intrinsic trigeminal pathway. This study highlights the utility of routine MRI to study the intrinsic anatomy of the trigeminal pathway in pathological conditions.

Towards the automatic computational assessment of enlarged perivascular spaces on brain magnetic resonance images: a systematic review

Enlarged perivascular spaces (EPVS), visible in brain MRI, are an important marker of small vessel disease and neuroinflammation. We systematically evaluated the literature up to June 2012 on possible methods for their computational assessment and analyzed confounds with lacunes and small white matter hyperintensities. We found six studies that assessed/identified EPVS computationally by seven different methods, and four studies that described techniques to automatically segment similar structures and are potentially suitable for EPVS segmentation. T2-weighted MRI was the only sequence that identified all EPVS, but FLAIR and T1-weighted images were useful in their differentiation. Inconsistency within the literature regarding their diameter and terminology, and overlap in shape, intensity, location, and size with lacunes, conspires against their differentiation and the accuracy and reproducibility of any computational segmentation technique. The most promising approach will need to combine various MR sequences and consider all these features for accurate EPVS determination.

Hypoyelination in I-cell disease; MRI, MR spectroscopy and neuropathological correlation

MRI of a female patient with genetically diagnosed I-cell disease at 2weeks, 4 and 8months revealed delayed myelination or hypomyelination with decreased choline on MR spectroscopy. Brain autopsy was performed 2h after death at 14-month-old. Immunoreactivities for myelin basic protein and proteolipid proteins, markers for mature myelin sheath, were reduced in the myelinated fibers and oligodendrocytes in the white matter, indicating the hypomyelination in the central nervous system. I-Cell disease should be added to the list of delayed or hypomyelination conditions, and this neuroimaging finding could be a key for differentiating I-cell disease from the clinically similar disorder of Hurler syndrome characterized by perivascular lacunation.

Leiomyosarcoma Leptomeningeal Brain Metastases

Brain metastases from soft tissue sarcomas (STS) occur late and relatively rarely, most commonly after lung metastases have developed. Furthermore, they are most commonly intraparenchymal in distribution. We describe two cases of histologically confirmed intracranial metastatic soft tissue leiomyosarcomas. In both cases all the nodular metastases measuring 10 mm in diameter or less could be easily detected in the leptomeningeal spaces by MRI. However, as the lesion enlarges it is difficult to recognize the site of origin, and the mass appears and behaves as intra-axial. Lesions located in the leptomeningeal spaces and in the perivascular space can be extremely small, which makes their detection problematic. For this reason we believe that in this context, MRI global gadolinium enhanced imaging using contiguous 1 mm slice thickness acquisition (TR 23 ms, TE 8 ms 512×512 matrix) is preferable, since the patient's management may vary depending on the multiplicity and location of the lesions.

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.

Brain and spinal MR imaging findings in mucopolysaccharidoses: a review

MPS represents a group of rare hereditary disorders characterized by multisystem involvement due to intralysosomal GAG accumulation. Among various tissues, both the central and peripheral nervous system are affected in almost all types of the disease. Thus, brain and spinal MR imaging are valuable tools for the assessment of neurologic involvement, and there is evidence that they might be reliable markers demonstrating disease severity and efficacy of treatment options currently used in patients with MPS. We aimed to review the most prominent MR imaging features of patients with MPS, paying attention to the physiopathologic mechanisms responsible for these alterations. Along with the description of neuroimaging findings, existing data in relation to their correlation with the severity of neurologic involvement is discussed, while another topic of great importance is the effect of various therapeutic regimens in the progression of brain and spinal MR imaging alterations. Finally, recent data concerning MR spectroscopy studies in MPS are also critically discussed.

Higher ambulatory blood pressure relates to enlarged Virchow-Robin spaces in first-ever lacunar stroke patients

Enlarged Virchow-Robin spaces (EVRS) are considered to be a sign of cerebral small vessel disease. Hypertension is an important risk factor for cerebral small vessel disease, whereas ambulatory blood pressure (BP) is the strongest predictor of hypertension-related brain damage. However, the association between ambulatory BP levels and EVRS has never been investigated. The aim of this study was to determine the association between ambulatory BP levels and EVRS. In 143 first-ever lacunar stroke patients, we performed 24-h ambulatory BP monitoring after the acute stroke phase. On brain MRI we counted EVRS in the basal ganglia and the centrum semiovale. We graded the number of EVRS at each level into a three-category severity scale. We assessed the association between BP levels and EVRS by ordinal regression analysis. After adjusting for age, sex, extensive white matter lesions, and asymptomatic lacunar infarcts, higher day systolic (OR 1.21; 95 % CI 1.00–1.46 per 10 mmHg), day diastolic (1.18; 95 % CI 1.02–1.37 per 5 mmHg) and 24-h diastolic (OR 1.18; 95 % CI 1.01–1.37 per 5 mmHg) ambulatory BP levels were associated with EVRS at the basal ganglia level. No relation was found between ambulatory BP levels and EVRS in the centrum semiovale. Higher day ambulatory BP levels are associated with EVRS in the basal ganglia. This association was independent of the presence of extensive white matter lesions and asymptomatic lacunar infarcts. Our results imply that basal ganglia EVRS should be regarded as a separate manifestation of BP-related brain damage.

The reliability of magnetic resonance imaging in traumatic brain injury lesion detection

OBJECTIVE

This study compares inter-rater-reliability, lesion detection and clinical relevance of T2-weighted imaging (T2WI), Fluid Attenuated Inversion Recovery (FLAIR), T2*-gradient recalled echo (T2*-GRE) and Susceptibility Weighted Imaging (SWI) in Traumatic Brain Injury (TBI).

METHODS

Three raters retrospectively scored 56 TBI patients' MR images (12-76 years old, median TBI-MRI interval 7 weeks) on number, volume, location and intensity. Punctate lesions (diameter <10 mm) were scored separately from large lesions (diameter ≥ 10 mm). Injury severity was assessed with the Glasgow Coma Scale (GCS), outcome with the Glasgow Outcome Scale-Extended (GOSE).

RESULTS

Inter-rater-reliability for lesion volume and punctate lesion count was good (ICC = 0.69-0.94) except for punctate lesion count on T2WI (ICC = 0.19) and FLAIR (ICC = 0.15). SWI showed the highest number of lesions (mean = 30.0), followed by T2*-GRE (mean = 15.4), FLAIR (mean = 3.1) and T2WI (mean = 2.2). Sequences did not differ in detected lesion volume. Punctate lesion count on T2*-GRE (r = -0.53) and SWI (r = -0.49) correlated with the GCS (p < 0.001).

CONCLUSIONS

T2*-GRE and SWI are more sensitive than T2WI and FLAIR in detecting (haemorrhagic) traumatic punctate lesions. The correlation between number of punctate lesions on T2*-GRE/SWI and the GCS indicates that haemorrhagic lesions are clinically relevant. The considerable inter-rater-disagreement in this study advocates cautiousness in interpretation of punctate lesions using T2WI and FLAIR.

Late stage infection in sleeping sickness

At the turn of the 19^th century, trypanosomes were identified as the causative agent of sleeping sickness and their presence within the cerebrospinal fluid of late stage sleeping sickness patients was described. However, no definitive proof of how the parasites reach the brain has been presented so far. Analyzing electron micrographs prepared from rodent brains more than 20 days after infection, we present here conclusive evidence that the parasites first enter the brain via the choroid plexus from where they penetrate the epithelial cell layer to reach the ventricular system. Adversely, no trypanosomes were observed within the parenchyma outside blood vessels. We also show that brain infection depends on the formation of long slender trypanosomes and that the cerebrospinal fluid as well as the stroma of the choroid plexus is a hostile environment for the survival of trypanosomes, which enter the pial space including the Virchow-Robin space via the subarachnoid space to escape degradation. Our data suggest that trypanosomes do not intend to colonize the brain but reside near or within the glia limitans, from where they can re-populate blood vessels and disrupt the sleep wake cycles.

Perivascular and perineural extension of formed and soluble blood elements in an intracerebral hemorrhage rat model

The perivascular and perineural extension of hematoma has recently been observed in the brain after intracerebral hemorrhage (ICH), which is formed by the leakage of hematoma via the Virchow-Robin spaces (VRS) and the spaces around the nerve fibers (perineurium). The present study investigated the perivascular and perineural extension of a hematoma by studying the distribution of the formed and soluble blood elements labeled with different fluorescein dyes at different times after ICH in a rat model. The ICH rat model was prepared using a modified double injection method. Autologous blood, which contained fluorescein isothiocyanate (FITC)-labeled RBCs or carboxytetramethylrhodamine (TAMRA)-labeled BSA, was injected into the center of the left caudate nucleus. Brain sections were prepared and observed by overlaying fluorescence and hematoxylin and eosin stained images. The formed blood elements extended mainly into the VRS and perineurium in the perihematomal tissue and ipsilateral brain regions near the hematoma. The soluble blood elements extended more extensively to almost all regions of the brain, including some remote brain areas, such as the contralateral cerebral hemisphere and brainstem. Moreover, the fluorescein dyes were observed in lymph sinuses in the bilateral deep cervical lymph nodes as early as 1 hour after ICH. Lymphostasis, which peaked three days after ICH, was observed in the brain tissues around hematoma. The current findings suggest that the perivascular and perineural extension of hematomas widespread distributes in the central nervous system, and is involved in a series of pathologic processes in ICH, such as the remote effects of a hematoma and lymphatic encephalopathy.

Spontaneous Regression of Dilated Virchow-Robin Spaces

We describe a 28-year-old woman with a dilated perivascular spaces in the right prerolandic district. The purpose of this article is to provide an in-depth overview of the MR imaging features of VR spaces and to describe magnetic resonance imaging evidence of complete regression of dilated perivascular spaces 2.

The Virchow-Robin spaces: delineation by magnetic resonance imaging with considerations on anatomofunctional implications

INTRODUCTION

The Virchow-Robin spaces (V-R spaces) are well-known, but not systematically understood fluid-filled perivascular spaces that allow the convexity and basal perforating vessels to penetrate deep into the cerebral parenchyma.

OBJECTIVE

This study aims to delineate anatomical characteristics of the normal V-R spaces by MR imaging with considerations on clinical and anatomofunctional implications of the V-R spaces.

METHODS

In this prospective study with 3T magnetic resonance (MR) imaging, the whole extent of the intracranial V-R spaces was classified into basal, cortical, subcortical, paraventricular, and brainstem segments, on the basis of the topological difference in 105 control subjects. Morphological characteristics in each segment of the V-R spaces are described. For comparison with the neuroimaging appearance, V-R spaces were histologically examined in cadaveric human brains. The physiological functions of the V-R spaces and pathognomonic implications of unusually dilated, but asymptomatic, V-R spaces encountered in five subjects are discussed.

RESULTS

The V-R spaces were found to form a complicated, while anatomically highly consistent, intraparenchymal canal network distributed over the whole cerebral hemispheres and connect the cerebral convexity, basal cistern, and ventricular system.

CONCLUSION

The V-R spaces may be essential for drainage routes of cerebral metabolites, additional buoyancy for the brain, and maintenance of homogenous intracranial pressure. MR imaging may be more advantageous in depicting the V-R spaces than histological examination.

Diffusion tensor imaging and tractography of the corticospinal tract in the presence of enlarged Virchow-Robin spaces

BACKGROUND AND PURPOSE

We report a patient with abnormal diffusion tensor imaging (DTI) and tractography of the corticospinal tract caused by mass effect from adjacent enlarged Virchow-Robin spaces.

METHODS

DTI was performed using 25 noncollinear directions. Fractional anisotropy (FA) and mean diffusivity (MD) maps were generated. Region-of-interest measurements of the corticospinal tracts were organized in histograms, and comparisons were made between sides. Statistical analysis consisted of a Wilcoxon rank-sum nonparametric test and a two-sample test of proportions to compare the relative percentage of voxels >.8.

RESULTS

The patient had no signs or symptoms of motor weakness. The corticospinal tract adjacent to the enlarged Virchow-Robin spaces showed significant changes in the proportion of FA > .8, distribution of FA and distribution of MD (P < .001).

CONCLUSIONS

Diffusion tensor changes may be caused by enlarged Virchow-Robin spaces in the absence of clinical signs or symptoms. We hypothesize that the DTI changes are due to alterations in the extravascular extracellular space. Tensor changes should be interpreted with caution in patients with space occupying mass lesions such as brain tumors.

Assessment of the Virchow-Robin Spaces in Alzheimer disease, mild cognitive impairment, and normal aging, using high-field MR imaging

BACKGROUND AND PURPOSE

VRSs are the perivascular spaces surrounding the deep perforating arteries in the brain. Although VRS variations with age and disease pathologies have been reported previously, the radiologic characteristics of the VRS in relation to AD are poorly understood. This study investigated the prevalence, spatial distribution, and severity of the VRS in AD, MCI, and older adults who were CN. It also investigated the relationship of the VRS to white matter changes.

MATERIALS AND METHODS

Structural MR imaging data were acquired from 158 participants (AD = 37, MCI = 71, CN = 50, mean age = 74.97 ± 7.20 years) who had undergone T1WI at 3T. The severity of VRS in the white matter, basal ganglia, hippocampus, and brain stem structures was evaluated by using a semiquantitative scale, adapted from existing rating scales. A VRS total score summarizing the subscales was calculated to assess the whole-brain VRSs.

RESULTS

VRSs were observed in multiple brain regions of all participants, typically presented as <2-mm well-margined symmetric round-, oval- and linear-shaped hypointensities on T1WI. The VRS total score increased with leukoaraiosis, atrophy, and advanced age (P < .001). Individuals with AD and MCI showed greater levels of VRS than control subjects. The VRS total score discriminated individuals with AD and those who were CN with an accuracy of 0.79 (95% CI, 0.69-0.89).

CONCLUSIONS

VRSs are common in older adults and are more severe in AD and MCI than in CN. Whether increased VRSs can be reliably used to aid in AD diagnosis warrants further investigation.

Silent Brain Infarcts

Background and Purpose—

Silent brain infarcts (SBIs) have been recognized as common lesions in elderly subjects and their diagnosis relies on brain imaging. In this study, we aimed to evaluate the different MRI parameters and criteria used for their evaluation in the literature to better understand the variation across studies and related limitations.

Method—

Original MRI studies of SBI performed in human populations and reported in the English literature were reviewed. Analyses were restricted to population-based studies or studies in which at least 50 subjects with SBI were detected. The MRI parameters as well as the MRI criteria of SBI (size, signal characteristics, and criteria for differentiation of dilated Virchow-Robin spaces) were described and analyzed.

Result—

Magnetic field strength, slice thickness, and gap between slices greatly varied among the 45 articles included in this review. The MRI definition of SBI was inconsistent across studies. In half of them, SBI was defined as hypointense on T1 and hyperintense on T2-weighted images. Exclusion criteria for dilated Virchow-Robin spaces were used only in 7 studies.

Conclusions—

The variation in MRI characteristics and diagnostic criteria for SBI represent a major limitation for interpretation and comparison of data between studies. Efforts are needed to reach unified imaging criteria for SBI.

Frequency and location of dilated Virchow-Robin spaces in elderly people: a population-based 3D MR imaging study

BACKGROUND AND PURPOSE

dVRS have been previously associated with aging and cerebrovascular diseases. However, little is known about their prevalence and topographic distribution in the general elderly population.

MATERIALS AND METHODS

dVRS were evaluated by using high-resolution 3D MR imaging in 1826 subjects enrolled in the 3C-Dijon MR imaging study. On T1-weighted MR imaging, dVRS were detected according to 3D imaging criteria and rated by using 4-level severity scores based in the BG or in the WM. The number and anatomic location of large dVRS (≥3 mm) were recorded.

RESULTS

dVRS were observed in the BG or WM in every subject. The severity of dVRS was significantly associated with higher age in both the BG and WM, whereas sex was related to the severity of dVRS only in the BG. Large dVRS were detected in 33.2% of participants. Status cribrosum was found in 1.3% of participants. dVRS were also highly prevalent within the hippocampus (44.5%) and hypothalamus (11.6%).

CONCLUSIONS

dVRS are always detected in the BG or WM in elderly people, and large dVRS are also prevalent. The topographic distribution of dVRS is not uniform within the brain and may depend on anatomic or pathologic characteristics interacting with aging and sex.

Hippocampal Asymmetry with Hippocampal Sulcus Remnants in a Patient with Mild Cognitive Impairment

A 65-year-old woman underwent MRI for a mild cognitive impairment (MCI) at Mini-Mental State Examination (MMSE). MRI showed hippocampal sulcus remnants bilaterally, although they were larger on the right, and left hippocampal atrophy with increased left fimbrio-subicular distance (right side: 1.2 mm; left side: 2.0 mm). The meaning of these findings in relation to clinical aspects is discussed and reviewed according to data from the literature.

Features of Virchow-Robin spaces in newly diagnosed multiple sclerosis patients

BACKGROUND

Virchow-Robin spaces (VRSs) are perivascular pia-lined extensions of the subarachnoid space around the arteries and veins as they enter the brain parenchyma. These spaces are responsible for inflammatory processes within the brain.

OBJECTIVES

This study was designed to shed more light on the location, size and shape of VRSs on 3mm slice thickness, 1.5 Tesla MRI scans of newly diagnosed MS patients in Isfahan, Iran and compare the results with healthy age- and sex-matched controls.

METHODS

We evaluated MRI scans of 73 MS patients obtained within 3 months of MS onset and compared them with MRI scans from 73 age- and sex-matched healthy volunteers. Three mm section proton density, T2W and FLAIR MR images were obtained for all subjects. The location, size and shape of VRSs were compared between the two groups.

RESULTS

The total number of VRSs was significantly more in the MS group (p<0.001). The distribution of VRSs were significantly more located in the high convexity areas in the MS group (p<0.001), while there was no significant differences in other regions. The round shaped VRSs were significantly more detected on MRI scans of MS patients, and curvilinear shapes were significantly more frequently observed in healthy volunteers, however there were no significant differences for oval shaped VRSs between the two groups. The number of VRSs with the size over than 2mm were significantly more observed in the MS groups compared to controls. We also observed some differences in the characteristics of VRSs between the genders in the MS group.

CONCLUSION

The results of this study shed more light on the usefulness of VRSs as an MRI marker for the disease. In addition, according to our results VRSs might also have implication to determine the prognosis of the disease. However, larger studies with more advanced MRI techniques are required to confirm our results.

Differential diagnosis of T2 hyperintense brainstem lesions: Part 1. Focal lesions

Brainstem lesions can be classified as focal or diffuse. Magnetic resonance imaging is the most suitable imaging modality for evaluating these lesions. As a rule, focal lesions are not large and have well-defined margins. Causes include tumors, vascular malformations, demyelinating diseases, brain abscesses, hypertrophic olivary degeneration, and dilated Virchow-Robin spaces. Differential diagnoses of these numerous entities mandates a review of magnetic resonance imaging findings in conjunction with epidemiologic aspects, clinical features, and other medical test results.

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.