A special form of cerebral lacunae: expanding lacunae

Enlarged tumefactive perivascular, or Virchow-Robin, spaces and hydrocephalus: do we need to treat? Illustrative cases

BACKGROUND

Perivascular spaces (PVSs) are spaces in brain parenchyma filled with interstitial fluid surrounding small cerebral vessels. Massive enlargements of PVSs are referred to as "giant tumefactive perivascular spaces" (GTPVSs), which can be classified into three types depending on their localization. These lesions are rare, predominantly asymptomatic, and often initially misinterpreted as cystic tumor formations. However, there are several reported cases in which GTPVSs have induced neurological symptoms because of their size, mass effect, and location, ultimately leading to obstructive hydrocephalus necessitating neurosurgical intervention. Presented here are three diverse clinical presentations of GTPVS.

OBSERVATIONS

Here, the authors observed an asymptomatic case of type 1 GTPVS and two symptomatic cases of type 3 GTPVS, one causing local mass effect and the other hydrocephalus.

LESSONS

GTPVSs are mostly asymptomatic lesions. Patients without symptoms should be closely monitored, and biopsy is discouraged. Hydrocephalus resulting from GTPVS necessitates surgical intervention. In these cases, third ventriculostomy, shunt implantation, or direct cyst fenestration are surgical options. For patients presenting with symptoms from localized mass effect, a thorough evaluation for potential neurosurgical intervention is imperative. Follow-up in type 3 GTPVS is recommended, particularly in untreated cases. Given the infrequency of GTPVS, definitive guidelines for neurosurgical treatment and subsequent follow-up remain elusive.

Perianeurysmal parenchymal cysts – Case series and literature review

•

Intracranial cysts are associated with a number of vascular lesions.

•

They predominantly occur in larger, partially-thrombosed aneurysms and in older patients.

•

There is a trend towards enlargement over time if untreated and a likelihood of recurrence following treatment.

•

We hypothesise the cysts arise either from dilated Virchow-Robin spaces and/or inflammatory processes.

Lacune and Large Perivascular Space: Two Kinds of Cavities Are of Different Risk Factors and Stroke Risk

BACKGROUND AND PURPOSE

To compare the risk factors and risk of stroke between lacune and large perivascular spaces (PVSs) in a community-based sample.

METHODS

Large PVSs were assessed using 3.0T MRI in a population-based cohort consisting of 1,204 participants. The relationship between cardiovascular risk factors, neuroimaging changes, and incidental stroke risk and the presence of lacune or large PVSs was assessed with univariate and multivariable ordinal logistic regression analysis.

RESULTS

Of the 1,204 study participants (55.7 ± 9.3 years, 37.0% men), a total of 347 large PVSs were detected in 235 (19.5%) subjects, while a total of 219 lacunes were detected in 183 subjects (15.2%). The presence of lacunes was found to be significantly associated with age, male gender, hypertension, and diabetes, whereas only age (p < 0.01) and ApoEε4 carrier status (p < 0.01) were related to the presence of large PVSs. Those who had lacunes detected on MRI at baseline had a significant increased risk of stroke (hazard ratio [HR] 4.68; 95% confidence interval [CI], 1.15-19.07) during the 3-year follow-up independent of age, gender, and other vascular risk factors. However, there was no significant relationship between the presence of large PVSs and incident stroke (HR 3.84; 95% CI, 0.82-18.04).

CONCLUSIONS

The lack of association between large PVSs and cardiovascular risk factors or risk of stroke indicated a nonvascular pathogenic mechanism underlying large PVSs, suggesting the importance of distinguishing large PVSs from lacunes in clinical practice.

Morphology of perivascular spaces and enclosed blood vessels in young to middle-aged healthy adults at 7T: Dependences on age, brain region, and breathing gas

Perivascular spaces (PVSs) are fluid-filled spaces surrounding penetrating blood vessels in the brain and are an integral pathway of the glymphatic system. A PVS and the enclosed blood vessel are commonly visualized as a single vessel-like complex (denoted as PVSV) in high-resolution MRI images. Quantitative characterization of the PVSV morphology in MRI images in healthy subjects may serve as a reference for detecting disease related PVS and/or blood vessel alterations in patients with brain diseases.

To this end, we evaluated the age dependences, spatial heterogeneities, and dynamic properties of PVSV morphological features in 45 healthy subjects (21–55 years old), using an ultra-high-resolution three-dimensional transverse relaxation time weighted MRI sequence (0.41 × 0.41 × 0.4 mm³) at 7T. Quantitative PVSV parameters, including apparent diameter, count, volume fraction (VF), and relative contrast to noise ratio (rCNR) were calculated in the white matter and subcortical structures. Dynamic changes were induced by carbogen breathing which are known to induce vasodilation and increase the blood oxygenation level in the brain.

PVSV count and VF significantly increased with age in basal ganglia (BG), so did rCNR in BG, midbrain, and white matter (WM). Apparent PVSV diameter also showed a positive association with age in the three brain regions, although it did not reach statistical significance. The PVSV VF and count showed large inter-subject variations, with coefficients of variation ranging from 0.17 to 0.74 after regressing out age and gender effects. Both apparent diameter and VF exhibited significant spatial heterogeneity, which cannot be explained solely by radio-frequency field inhomogeneities. Carbogen breathing significantly increased VF in BG and WM, and rCNR in thalamus, BG, and WM compared to air breathing.

Our results are consistent with gradual dilation of PVSs with age in healthy adults. The PVSV morphology exhibited spatial heterogeneity and large inter-subject variations and changed during carbogen breathing compared to air breathing.

Concomitant enlargement of perivascular spaces and decrease in glymphatic transport in an animal model of cerebral small vessel disease

OBJECTIVES

To observe glymphatic transport and evaluate enlarged perivascular spaces (PVSs) in spontaneously hypertensive rats (SHRs).

METHODS

SHRs were used as an animal model of cerebral small vessel disease, and Wistar Kyoto (WKY) rats were used as the control group. Histopathology was used to evaluate the enlargement of PVSs. A fluorescent tracer was infused into the cisterna magna of rats, and the proportion of the brain parenchyma area exposed to the fluorescent tracer was later quantified to evaluate the influx and efflux function of the glymphatic system. The global and polarized expression of aquaporin protein 4 (AQP4) was analyzed by immunofluorescence.

RESULTS

Compared with WKY rats, SHRs exhibited obviously enlarged PVSs and significantly decreased influx and efflux function of the glymphatic system. The results showed a significant decrease in AQP4 polarity in SHRs, but a difference in global AQP4 expression was not observed between SHRs and WKY rats.

CONCLUSIONS

Impaired glymphatic transport may be involved in the pathogenesis of arteriolosclerotic cerebral small vessel disease, and enlarged PVSs may be a manifestation of the impaired glymphatic system.

MRI-based evaluation of structural degeneration in the ageing brain: Pathophysiology and assessment

Advances in MRI technology have significantly contributed to our ability to understand the process of brain ageing, allowing us to track and assess changes that occur during normal ageing and neurological conditions. This paper focuses on reviewing structural changes of the ageing brain that are commonly seen using MRI, summarizing the pathophysiology, prevalence, and neuroanatomical distribution of changes including atrophy, lacunes, white matter lesions, and dilated perivascular spaces. We also review the clinically accessible methodology for assessing these MRI-based changes, covering visual rating scales, as well computer-aided and fully automated methods. Subsequently, we consider novel assessment methods designed to evaluate changes across the whole brain, and finally discuss new directions in this field of research.

A Giant Tumefactive Perivascular Space: A Rare Cause of Obstructive Hydrocephalus and Monoparesis

Cerebral perivascular spaces (PVSs), otherwise known as Virchow-Robin spaces, are interstitial fluid-filled channels, <2 mm in diameter that form around arterial perforators as they course from the cortex into the brain parenchyma. In contrast, a giant tumefactive PVS is a rare entity comprising of clusters of such channels larger than 15mm resembling a neoplastic process as the name suggests. We report a 55-year-old male who presented with unsteady gait, cognitive decline, and left lower limb weakness for 6 months. Magnetic resonance imaging revealed a noncontrast enhancing multicystic intraaxial lesion of the right mesencephalon-diencephalon junction extending into the anterior third ventricle causing obstructive hydrocephalus. A ventriculoperitoneal shunt was inserted with a complete reversal of his neurological symptoms. Such PVSs can easily be misidentified for a cystic tumor, and their unique radiological features are discussed to prevent unnecessary surgery. We also demonstrate that when they cause hydrocephalus and midbrain compression symptoms cerebrospinal fluid shunting alone can result in excellent outcomes.

Posterior fossa giant tumefactive perivascular spaces: 8-year follow-up in an adolescent

Background:

Cystic masses in the posterior fossa are ominous appearing lesions with broad differential diagnosis. Giant tumefactive perivascular spaces (GTPS) are rarely occurring pathological findings in the posterior fossa with unclear etiology and ill-defined long-term prognosis.

Case Description:

We present a case of a 15-year-old male diagnosed with posterior fossa GTPS. The patient remained asymptomatic during the 8-year follow-up after diagnosis with the serial magnetic resonance imaging (MRI) showing no change in the size and morphology of the lesion.

Conclusion:

This case supports prior literature on supratentorial GTPS suggesting that the natural history of GTPS is mostly benign. Identification of GTPS in the posterior fossa could prevent the patient from unnecessary surgery or other aggressive treatment modalities.

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.

Tumefactive perivascular spaces mimicking cerebral edema in a patient with diabetic hyperglycemic hyperosmolar syndrome: a case report

Introduction

Acute cerebral edema is a significant cause of death in patients treated for diabetic ketoacidosis and hyperglycemic hyperosmolar syndrome.

Case presentation

We present the case of a 44-year-old African American woman admitted with acute severe headache and diagnosed with diabetic hyperglycemic hyperosmolar syndrome. Computed tomography of the head showed diffuse leukoencephalopathy, but sparing of the cortex. We were concerned for acute cerebral edema secondary to hyperglycemic hyperosmolar syndrome. Magnetic resonance imaging of the brain showed numerous collections of cystic spaces in the white matter of both hemispheres representing tumefactive perivascular spaces. Her headache improved with correction of the hyperglycemic hyperosmolar state.

Conclusion

Although the clinical presentation and head computed tomography were concerning for cerebral edema, the distinctive features on brain magnetic resonance imaging helped to clarify the diagnosis and differentiate it from other processes.

[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.

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.

Giant tumefactive perivascular spaces that expanded and became symptomatic 14 years after initial surgery

BACKGROUND

Perivascular spaces (PVSs) or Virchow-Robin spaces in the brain are pial-lined interstitial fluid (ISF)-filled structures surrounding the penetrating arteries and arterioles. These spaces appear as 1- to 2-mm in diameter, round, oval, or curvilinear smooth-walled structures on magnetic resonance imaging (MRI). Typical PVSs are asymptomatic. Occasionally, they become enlarged and cause specific clinical manifestations that depend on location and the degree of tissue compression. In this case, they are referred to as giant tumefactive PVSs. To our knowledge, there have been no reported cases in which giant PVSs increased remarkably in number and size during both the natural course and postoperative course. We describe a rare progression of giant tumefactive PVSs 14 years after initial surgery.

CASE DESCRIPTION

On first admission at age 17, endoscopic ventriculocystostomy and third ventriculostomy were performed to relieve hydrocephalus caused by cysts compressing the cerebral aqueduct. Fourteen years later, the multicystic lesion reappeared with an increase in both cyst number and size. The patient showed no hydrocephalus but presented with oculomotor and trochlear nerve palsies, which were caused by a mass effect on the midbrain. Endoscopic ventriculocystostomy was performed and symptoms improved.

CONCLUSION

This is the first case report in which giant PVSs increased significantly in number and size.

Mesencephalic enlarged Virchow-Robin spaces in a 6-year-old boy: a case-based update

BACKGROUND

Perivascular spaces or Virchow-Robin spaces are normal anatomical structures within the brain, typically less than 5 mm in diameter. Rarely, they can reach much larger sizes and adopt bizarre single or multi-cystic configurations, as was the case in the patient that we report on. When there is such markedly gross dilatation, the phenomenon is known as Giant or tumefactive perivascular space enlargement.

CASE REPORT

We report a 6-year-old boy with a multi-cystic mesencephalic lesions presenting with obstructive hydrocephalus secondary to obstruction of the aqueduct of Sylvius due to tumefactive dilatation of Virchow-Robin spaces. The patient underwent an endoscopic fenestration and biopsy of the cystic portion abutting into the ventricular system.

CONCLUSION

In this paper, we discuss the phenomenon of perivascular (Virchow-Robin) spaces and their treatment options and review the relevant literature. To our knowledge, this is the first pediatric case of tumefactive dilatation of the Virchow-Robin spaces causing obstructive hydrocephalus that were directly fenestrated using neuroendoscopy.

An Unusual Cause of Blepharospasm

We describe a rare case of multiple dilated Virchow-Robin spaces in the brainstem in a patient presenting initially with blepharospasm with subsequent spread to involve the face and neck. On magnetic resonance imaging (MRI), these lesions demonstrated an isointense signal to cerebrospinal fluid on all sequences with no mass effect or enhancement. Although rare, this condition should be considered part of the differential diagnosis when evaluating cystic abnormalities in the brainstem. This is the first reported case of blepharospasm with subsequent orofacial and neck dystonia caused by dilated Virchow-Robin spaces. The imaging findings and differential diagnoses are discussed.

Giant tumefactive perivascular spaces manifesting as chorea bilaterally

Virchow-Robin (VR) spaces or perivascular spaces (PVSs) of the brain are pial-lined interstitial fluid-filled structures that accompany penetrating arteries and arterioles for a variable distance as they descend into the cerebral substance. VR spaces can be identified on magnetic resonance (MR) images obtained in patients of all ages in many areas of the brain. Infrequently, these become remarkably enlarged, and can assume configurations that may be mistaken for a more clinically significant disease, such as a cystic neoplasm or parasitic infections like cysticercosis. We report the first MR imaging description of a case of giant tumefactive (PVSs) manifesting as chorea bilaterally.

Developmental dilatation of Virchow-Robin spaces: a genetic disorder?

In childhood, widening of Virchow-Robin spaces is rarely secondary to specific progressive disorders, but more often appears in poorly characterized developmental conditions. From data collected in a neuropediatric department, we examined whether clinical data associated with "constitutional widening of Virchow-Robin spaces" allowed delineation of recognizable entities. Signs in 10 patients, mostly boys, suggested nonspecific cerebral dysfunctions, e.g., developmental delay, nonspecific epilepsy, headaches, or benign macrocephaly. Spaces were sometimes round, subsequently mimicking microcystic malacic lesions. In two patients, abnormal magnetic resonance imaging signals were evident in white matter contiguous to widened perivascular spaces, suggesting a broader disorder of fluid exchanges. Four cases occurred in two sibships. In two families, other patients exhibited early developmental difficulties. Long-term clinical and magnetic resonance imaging surveillance will clarify which cases of primary Virchow-Robin space dilatation imply a benign prognosis. Performance of magnetic resonance imaging on any relative exhibiting minor neuropsychologic handicaps would permit estimations of real genetic incidence.

Virchow-Robin spaces at MR imaging

Virchow-Robin (VR) spaces surround the walls of vessels as they course from the subarachnoid space through the brain parenchyma. Small VR spaces appear in all age groups. With advancing age, VR spaces are found with increasing frequency and larger apparent sizes. At visual analysis, the signal intensity of VR spaces is identical to that of cerebrospinal fluid with all magnetic resonance imaging sequences. Dilated VR spaces typically occur in three characteristic locations: Type I VR spaces appear along the lenticulostriate arteries entering the basal ganglia through the anterior perforated substance. Type II VR spaces are found along the paths of the perforating medullary arteries as they enter the cortical gray matter over the high convexities and extend into the white matter. Type III VR spaces appear in the midbrain. Occasionally, VR spaces have an atypical appearance. They may become very large, predominantly involve one hemisphere, assume bizarre configurations, and even cause mass effect. Knowledge of the signal intensity characteristics and locations of VR spaces helps differentiate them from various pathologic conditions, including lacunar infarctions, cystic periventricular leukomalacia, multiple sclerosis, cryptococcosis, mucopolysaccharidoses, cystic neoplasms, neurocysticercosis, arachnoid cysts, and neuroepithelial cysts.

Giant mesencephalothalamic virchow-robin spaces causing obstructive hydrocephalus. A case report

Virchow-Robin spaces accompany arteries for a variable distance into the brain substance. They are usually small but can be identified on high resolution MRI images in patients of all age groups. We report a rare case of a 40-year-old woman with giant mesencephalothalamic Virchow-Robin spaces which caused hydrocephalus requiring CSF diversion. After right ventriculoperitoneal shunt the patient recovered completely.

A case of disseminated polycystic dilated perivascular spaces presenting with dementia and parkinsonism

The perivascular spaces (PVSs) of the brain are lined with pia and contain interstitial fluid. In general, PVSs are small, asymptomatic, and identifiable at all ages. When PVSs are significantly enlarged, they can produce various clinical manifestations such as headache and dizziness. A 67-year-old man was admitted with cognitive impairment and gait disturbance with a 5-month history. Brain MRI showed multiple cystic PVSs in periventricular and subcortical white matter of both hemispheres. Medication with dopaminergic agents produced a moderate clinical improvement, while anticholinesterase was not effective. This case suggests that disseminated polycystic dilated PVSs may present with dementia and Parkinsonism.

Virchow-Robin spaces on magnetic resonance images: normative data, their dilatation, and a review of the literature

INTRODUCTION

Virchow-Robin spaces (VRS) are perivascular spaces in the brain and can be visualized on magnetic resonance images (MRI). We attempt to provide a better understanding of the significance of VRS for pathological and physiological processes by reviewing the literature, presenting normative data for the first time, and proposing a definition for the dilatation of the VRS on MRI that is based on shape rather than size.

METHODS

We evaluated the VRS in 125 healthy subjects (age range 1-30 years) using high-resolution 3D images, and in 36 patients (age range 2-16 years) with normal MRI, using routine clinical sequences.

RESULTS

VRS were visible in all high-resolution images of the 125 healthy subjects. Two of them revealed dilated VRS, giving a prevalence of 1.6%. VRS could be visualized in 29 (80%) of the 36 paediatric clinical scans; none was dilated. It was demonstrated that the visibility of VRS on MRI is sequence-dependent.

CONCLUSION

From the results of this study and the literature on the nature and pathology of VRS, we conclude that VRS on MR images of healthy individuals are normal findings, even if they are dilated. A judgement on whether dilated VRS in an individual patient is a normal variant or part of a disease process can be made by taking into account the appearance of the adjacent tissue on MRI and the clinical context.

Enlarged perivascular spaces mimicking multicystic brain tumors

✓ The authors present two cases in which enlarged Virchow—Robin spaces were located in the basal ganglia and the thalamomesencephalic region. The incidence of such huge cystic lesions is extremely rare. The expanding nature of these lesions, demonstrated by the patients' progressive symptoms due to compression of the adjacent brain parenchyma and obstructive hydrocephalus, mimicked that of brain tumors. The two patients were successfully treated by neuroendoscopic cystocisternostomy or ventriculocystostomy. To the authors' knowledge there have been only two published reports on expanding Virchow—Robin spaces that produced a compressive effect or consequent hydrocephalus and were directly fenestrated using neuroendoscopic techniques. Neuroendoscopy appears to offer an effective surgical option in the treatment of symptomatic Virchow—Robin spaces.

MR imaging of normal perivascular space expansion at midbrain

BACKGROUND AND PURPOSE

A previous investigation of the MR imaging findings in the midbrain reported expanded perivascular (PV) spaces in only the ponto-mesencepalic junction (PMJ) in 20% of healthy subjects, whereas pathologically expanding PV spaces have been reported at the mesencephalo-diencephalic junction (MDJ) as multi-lobulated, cystic lesions with signal intensity compatible with that of CSF that cause aqueductal stenosis. To clarify the anatomical distinctions between normally expanded and pathologically expanding PV spaces, we defined their distribution in the normal midbrain by using high-spatial-resolution MR imaging.

METHODS

Heavily T2-weighted MR imaging was performed in 115 adult subjects with neurologic complaints without cerebral disease. Histologic studies were performed from two normal midbrain blocks.

RESULTS

Expanded PV spaces were visible at the PMJ in 87% of subjects and at the MDJ in 63% of subjects. On axial images, ovoid or linear lesions with signal intensity compatible to CSF were present behind the cerebral peduncle at both the PMJ and MDJ. These areas varied from less than 1 mm to 5 mm (maximum diameter on coronal sections). Histologic studies confirmed the distribution of expanded PV spaces, as noted on MR images.

CONCLUSION

This study, by using high-spatial-resolution MR imaging, revealed that expanded PV spaces were visible at the PMJ and MDJ. Our finding of expanded PV spaces normally present at the MDJ may be related to pathologically expanding PV spaces, which should be kept in mind as a differential diagnosis for intraparenchymal cystic lesions in the midbrain with signal intensity compatible to CSF.

Giant tumefactive perivascular spaces

BACKGROUND AND PURPOSE

The brain perivascular spaces (PVSs) are pial-lined, interstitial fluid-filled structures that accompany penetrating arteries. When enlarged, they may cause mass effect and can be mistaken for more ominous pathologic processes. The purpose of this study was to delineate the broad clinical and imaging spectrum of this unusual condition.

METHODS

Thirty-seven cases of giant PVSs were identified from 1988 to 2004 and were retrospectively reviewed. Clinical data collected included patient demographics, presenting symptoms, and follow-up. Histopathologic data were reviewed when available. Images were evaluated for size and location of the giant PVSs, associated mass effect, hydrocephalus, adjacent white matter changes, and contrast enhancement.

RESULTS

There were 24 men and 13 women with an age range of 6-86 years, (mean 46 years). The most common presenting feature was headache (15 patients). Thirty-two cases had multilocular clusters of variably sized cysts. Five lesions were unilocular. All lesions had signal intensity comparable to CSF and did not enhance. The most common location for the giant PVSs was the mesencephalothalamic region (21/36). Fourteen were located in the cerebral white matter; two were in the dentate nuclei. Nine giant mesencephalothalamic PVSs had associated hydrocephalus, which required surgical intervention.

CONCLUSION

Giant tumefactive PVSs most often appear as clusters of variably sized cysts that are isointense relative to CSF and do not enhance. They are most common in the mesencephalothalamic region and may cause hydrocephalus. Although they may have striking mass effect, giant PVSs should not be mistaken for neoplasm or other diseases.

Surgical considerations regarding giant dilations of the perivascular spaces

Object. Dilations of brain perivascular spaces (PVSs), also known as Virchow—Robin spaces, are routinely identified on magnetic resonance imaging studies of the brain and recognized as benign normal variants. Giant dilations occur only rarely and can be easily misdiagnosed as central nervous system tumors. The relevant surgical literature was reviewed to help establish indications for surgical intervention in these typically benign lesions.

Methods. Giant dilations of the PVSs in 12 patients who had undergone surgery for several different indications were identified. Both clinical and radiographic presentations of these patients were reviewed along with the surgical procedures.

Conclusions. Dilations of the PVSs can become giant lesions that may necessitate surgical intervention to relieve mass effect or hydrocephalus. The relationship of these lesions to neurological symptoms such as tremor and seizures remains unclear.

Expanding Virchow Robin spaces in the midbrain causing hydrocephalus

We describe a patient who showed cystic lesions in the midbrain and obstructive hydrocephalus. MR imaging features corresponded to abnormal dilatation of perivascular spaces. Similar clinical and MR imaging findings were described in previous reports of patients presenting with mesencephalo-thalamic expanding lacunae; the diagnosis of some of those cases was confirmed at postmortem examination This condition is extremely rare but should be part of a differential diagnosis when evaluating cystic abnormalities in this area of the brain.

Expanding lacunae causing triventricular hydrocephalus. Report of two cases

Two patients are reported in whom the presence of triventricular hydrocephalus and aqueductal obstruction or stenosis due to multiple expanding lacunae in the mesencephalothalamic region possibly corresponds to abnormally dilated perivascular spaces. Placement of a ventriculoperitoneal cerebrospinal fluid (CSF) shunt in one patient and the performance of a third ventricle cisternotomy in the other reversed the hydrocephalic syndrome, but did not modify the complex neuroophthalmological disturbance and rubral tremor presumably related to the compressive effects of the lacunae on adjacent parenchyma. In one patient the number and size of the lacunae were increased 4 years after CSF shunt placement. A review of the literature revealed two cases in which magnetic resonance imaging demonstrated a similar, poorly understood pathological condition.

[Electrophysiologic study in a patient presenting with expanding cerebral lacunae]

A 42-year-old man was affected with multiple cerebral lesions suggesting expanding lacunae. He had suffered for about 15 years of headaches and blurred vision. Neurological examination showed a Parinaud syndrome and a skew deviation. Magnetic resonance imaging showed an enlargement of the third and lateral ventricles and multiple intraparenchymatous lesions with a signal similar to that of the cerebrospinal fluid. These lesions were located in the mesencephalon and right thalamic region. Important discrepancies between the topography of the lesion and the clinical data were observed. Neurological examination, ocular movements during wake and neuropsychological testing suggested sub-cortical dysfunction. These results suggest functional rather than lesional repercussion of expansive lacunae.