Dementia with leucoaraiosis and dural arteriovenous malformation: clinical and PET case study

Reversible Dementia With Bilateral White Matter Changes Caused by Dural Arteriovenous Fistula: Case Report and Review of the Literature

INTRODUCTION

Dural arteriovenous fistula (DAVF) is a vascular malformation. Although rare, DAVFs can represent a potentially reversible cause of dementia. Bilateral white matter changes can be detected on the magnetic resonance imaging of patients with DAVFs. Familiarity with symptoms of DAVFs can reduce the incidence of misdiagnosis of dementia syndrome. This study aimed to explore the clinical manifestation, imaging characteristics, and prognosis of dementia with bilateral white matter changes caused by DAVFs.

CASE REPORT

A 56-year-old man presented with memory deterioration, tinnitus, and weakness in both lower limbs for over 2 months. Magnetic resonance imaging of the brain revealed white matter signal changes in the bilateral ventricles and centrum semiovale, which manifested as low signal on T1-weighted imaging, high signal on T2-weighted imaging, fluid-attenuated inversion recovery, and diffusion-weighted imaging. Digital subtraction angiography revealed DAVFs along the lateral sinus. The patients' condition improved significantly after endovascular embolization of the DAVFs.

CONCLUSIONS

DAVFs presenting with dementia are rare and cases with bilateral white matter alterations can be easily misdiagnosed as other diseases. If the patient has dementia and bilateral alterations in the white matter, a DAVF should be considered. This type of dementia is reversible and may be associated with venous hypertension caused by arteriovenous fistulas. Early digital subtraction angiography is important to reduce misdiagnoses.

Gradual Cerebral Hypoperfusion Impairs Fear Conditioning and Object Recognition Learning and Memory in Mice: Potential Roles of Neurodegeneration and Cholinergic Dysfunction

In the present study, male C57BL/6J mice were subjected to gradual cerebral hypoperfusion by implanting an ameroid constrictor (AC) on the left common carotid artery (CCA) and a stenosis on the right CCA. In the sham group, all surgical procedures were kept the same except no AC was implanted and stenosis was not performed. One month following the surgical procedures, fear conditioning and object recognition tests were conducted to evaluate learning and memory functions and motor functions were assessed using a balance beam test. At the experimental endpoint, mice were perfused and brains were collected for immunostaining and histology. Learning and memory as well as motor functions were significantly impaired in the hypoperfusion group. The immunoreactivity to choline acetyltransferase was decreased in dorsal striatum and basal forebrain of the hypoperfusion group indicating that cholinergic tone in these brain regions was compromised. In addition, an increased number of Fluoro-Jade positive neurons was also found in cerebral cortex, dorsal striatum and hippocampus indicating neurodegeneration in these brain regions. Based on this pattern of data, we argued that this mouse model would be a useful tool to investigate the therapeutic interventions for the treatment of vascular dementia. Additionally, this model could be employed to exploit the effect of microvascular occlusions on cognitive impairment in the absence and presence of Alzheimer's disease pathology.

The neuron-astrocyte-microglia triad in CA3 after chronic cerebral hypoperfusion in the rat: Protective effect of dipyridamole

We investigated the quantitative and morphofunctional alterations of neuron-astrocyte-microglia triads in CA3 hippocampus, in comparison to CA1, after 2 Vessel Occlusion (2VO) and the protective effect of dipyridamole. We evaluated 3 experimental groups: sham-operated rats (sham, n=15), 2VO-operated rats treated with vehicle (2VO-vehicle, n=15), and 2VO-operated rats treated with dipyridamole from day 0 to day 7 (2VO-dipyridamole, n=15), 90days after 2VO. We analyzed Stratum Pyramidalis (SP), Stratum Lucidum (SL) and Stratum Radiatum (SR) of CA3. 1) ectopic neurons increased in SL and SR of 2VO-vehicle, and 2VO-dipyridamole rats; 2) apoptotic neurons increased in SP of 2VO-vehicle rats and dipyridamole reverted this effect; 3) astrocytes increased in SP, SL and SR of 2VO-vehicle and 2VO-dipyridamole rats; 4) TNF-α expression increased in astrocytes, blocked by dipyridamole, and in dendrites in SR of 2VO-vehicle rats; 5) total microglia increased in SL and SR of 2VO-vehicle and 2VO-dipyridamole rats; 6) triads increased in SR of 2VO-vehicle rats and dipyridamole reverted this effect. Microglia cooperated with astrocytes to phagocytosis of apoptotic neurons and debris, and engulfed ectopic non-fragmented neurons in SL of 2VO-vehicle and 2VO-dipyridamole rats, through a new mechanism called phagoptosis. CA3 showed a better adaptive capacity than CA1 to the ischemic insult, possibly due to the different behaviour of astrocytes and microglial cells. Dipyridamole had neuroprotective effects.

Dural arteriovenous fistula-induced thalamic dementia: report of 4 cases

Nonhemorrhagic neurological deficits are underrecognized symptoms of intracranial dural arteriovenous fistulas (dAVFs) having cortical venous drainage. These symptoms are the consequence of cortical venous hypertension and portend a clinical course with increased risk of neurological morbidity and mortality. One rarely documented and easily misinterpreted type of nonhemorrhagic neurological deficit is progressive dementia, which can result from venous hypertension in the cortex or in bilateral thalami. The latter, which is due to dAVF drainage into the deep venous system, is the less common of these 2 dementia syndromes. Herein, the authors report 4 cases of dAVF with venous drainage into the vein of Galen causing bithalamic edema and rapidly progressive dementia. Two patients were treated successfully with endovascular embolization, and the other 2 patients were treated successfully with endovascular embolization followed by surgery. The radiographic abnormalities and presenting symptoms rapidly resolved after dAVF obliteration in all 4 cases. Detailed descriptions of these 4 cases are presented along with a critical review of 15 previously reported cases. In our analysis of these 19 published cases, the following were emphasized: 1) the clinical and radiographic differences between dAVF-induced thalamic versus cortical dementia syndromes; 2) the differential diagnosis and necessary radiographic workup for patients presenting with a rapidly progressive thalamic dementia syndrome; 3) the frequency at which delays in diagnosis occurred and potentially dangerous and avoidable diagnostic procedures were used; and 4) the rapidity and completeness of symptom resolution following dAVF treatment.

Cerebral hemodynamic disturbance in dural arteriovenous fistula with retrograde leptomeningeal venous drainage: a prospective study using 123I-iodoamphetamine single photon emission computed tomography

OBJECT

The severity of cerebral hemodynamic disturbance caused by retrograde leptomeningeal venous drainage (RLVD) of a dural arteriovenous fistula (dAVF) is related to neurological morbidity and unfavorable outcome. However, the cerebral hemodynamics of this disorder have not been elucidated well. The aim of this study was to assess the relationship between the cerebral venous congestive encephalopathy represented as a high-intensity area (HIA) on T2-weighted MR images and the cerebral hemodynamics examined by 123I-iodoamphetamine (IMP) single photon emission computed tomography (SPECT), as well as the predictive value of 123I-IMP SPECT for the development and reversibility of venous congestion encephalopathy.

METHODS

Based on the pre- and posttreatment T2 HIAs associated with venous congestion encephalopathy, patients were divided into 3 groups: a normal group, an edema group, and an infarction group. The regional cerebral blood flow (rCBF) at the region with RLVD was analyzed by 123I-IMP SPECT, and the results were compared among the groups.

RESULTS

There were 11, 6, and 3 patients in the normal, edema, and infarction groups, respectively. No patients in the normal group showed any symptoms related to venous congestion. In contrast, all patients in the edema and infarction groups developed neurological symptoms. The rCBF in the edema group was significantly lower than that in the normal group, and significantly higher than that in the infarction group. The cerebral vascular reactivity (CVR) of the infarction group was significantly lower than that of the normal and edema groups. After treatment, the neurological signs disappeared in the edema group, but only partial improvement was seen in the infarction group. The rCBF also significantly increased in the normal and edema groups, but not in the infarction group.

CONCLUSIONS

Quantitative rCBF measurement is useful for evaluating hemodynamic disturbance in dAVF with RLVD. The reduction of rCBF was strongly correlated with the severity of venous congestive encephalopathy, and loss of CVR is a reliable indicator of irreversible venous infarction caused by RLVD.

The neuron-astrocyte-microglia triad in a rat model of chronic cerebral hypoperfusion: protective effect of dipyridamole

Chronic cerebral hypoperfusion during aging may cause progressive neurodegeneration as ischemic conditions persist. Proper functioning of the interplay between neurons and glia is fundamental for the functional organization of the brain. The aim of our research was to study the pathophysiological mechanisms, and particularly the derangement of the interplay between neurons and astrocytes-microglia with the formation of "triads," in a model of chronic cerebral hypoperfusion induced by the two-vessel occlusion (2VO) in adult Wistar rats (n = 15). The protective effect of dipyridamole given during the early phases after 2VO (4 mg/kg/day i.v., the first 7 days after 2VO) was verified (n = 15). Sham-operated rats (n = 15) were used as controls. Immunofluorescent triple staining of neurons (NeuN), astrocytes (GFAP), and microglia (IBA1) was performed 90 days after 2VO. We found significantly higher amount of "ectopic" neurons, neuronal debris and apoptotic neurons in CA1 Str. Radiatum and Str. Pyramidale of 2VO rats. In CA1 Str. Radiatum of 2VO rats the amount of astrocytes (cells/mm(2)) did not increase. In some instances several astrocytes surrounded ectopic neurons and formed a "micro scar" around them. Astrocyte branches could infiltrate the cell body of ectopic neurons, and, together with activated microglia cells formed the "triads." In the triad, significantly more numerous in CA1 Str. Radiatum of 2VO than in sham rats, astrocytes and microglia cooperated in the phagocytosis of ectopic neurons. These events might be common mechanisms underlying many neurodegenerative processes. The frequency to which they appear might depend upon, or might be the cause of, the burden and severity of neurodegeneration. Dypiridamole significantly reverted all the above described events. The protective effect of chronic administration of dipyridamole might be a consequence of its vasodilatory, antioxidant and anti-inflammatory role during the early phases after 2VO.

Dural arteriovenous fistula presents like an ischemic stroke

OBJECTIVE

We report the case of a patient with a dural arteriovenous fistula whose neurobehavioral syndrome was indistinguishable from that of an ischemic stroke.

BACKGROUND

Case studies of dural arteriovenous fistulas primarily describe global cognitive changes like dementia, but detailed neurocognitive evaluations of dural arteriovenous fistula patients are rarely reported.

METHOD

We provide a dural arteriovenous fistula case of a patient who presented with aphasia and other symptoms of stroke. Background history, serial neuropsychological data, and angiographic images are presented.

RESULTS AND CONCLUSIONS

Serial neurocognitive data show the extent to which cognitive deficits are reversed with embolization. The case demonstrates that the mechanisms underlying neurocognitive deficits are specific to the fistula's unique hemodynamic features in addition to the location of the dural arteriovenous fistula.

Fistules durales à drainage veineux cortical

Dural fistulas are acquired arteriovenous shunts, accounting for 10-15p.cent of cerebrovascular malformations. Symptoms are commonly tinnitus or intracranial hemorrhage. Rarely, patients with dural fistulas can present with rapid cognitive impairment. We report two women with rapidly evolving dementia. Cerebral angiography revealed dural arteriovenous fistula, with retrograde drainage into cortical veins, related to thrombosis of both transverse sinuses. Intra-arterial and intra-venous endovascular approaches failed to cure the fistula. Venous embolization via a transcranial approach was required to occlude the fistula, leading to resolution of the symptoms. Dural arteriovenous fistulas may lead to dementia with diffuse white matter changes related to venous ischemia, and must be considered as a reversible cause of vascular dementia. A transcranial approach for venous embolization is sometimes required.

Cognitive impairment and chronic cerebral hypoperfusion: what can be learned from experimental models

The relation between chronic cerebral hypoperfusion and cognitive functions has not been completely clarified. The resolution of cerebral hypoperfusion states, such as those induced by arteriovenous malformations or carotid stenosis/occlusion, has been reported to improve mental decline in humans. Subcortical vascular dementia is another human condition supposed to be linked with chronic cerebral hypoxia/ischemia. The extent of this cause/effect relation is, however, difficult to be assessed in humans, where different factors, such as ageing or subtle degenerative processes, can coexist and interact influencing cognitive performances. Experimental studies can help to elucidate this relation because they can use models of pure chronic/moderate cerebral hypoperfusion. An experimental model of chronic ischemia is the bilateral common carotid artery occlusion in the rat. In this paper, we present a review of experimental studies that evaluated cognitive functions in the rat with bilateral common carotid artery occlusion. We then present an experimental model of bilateral common carotid artery occlusion in the rat modified with respect to previous papers regarding both the surgical procedure and the neurocognitive evaluation that is focused on cognitive domains depending on subcortical-frontal circuits. We propose this model to investigate subcortical vascular dementia.

Persistent impairment of gait performances and working memory after bilateral common carotid artery occlusion in the adult Wistar rat

BACKGROUND

The clinical and pathophysiological effects of a chronic reduction of cerebral blood flow in humans are not completely known. We investigated whether rats subjected to bilateral common carotid artery occlusion (bCCA-o) developed focal neurological deficits, gait dysfunction, and working memory alterations.

METHODS

Eighteen male Wistar rats were subjected to bCCA-o, 13 were sham-operated. We assessed sensorimotor functions, gait on a 60 cm-long elevated bridge, and working memory (object recognition and Y maze tests) before and 30, 60, and 90 days after surgery. Histological analysis was performed in a subgroup of 10 rats.

RESULTS

No rat showed sensorimotor alterations after surgery. Although gait performances of both bCCA-o and sham-operated rats declined over time, the differences reached statistical significance only for the bCCA-o group (mean+/-SE: 26.8+/-5.0; 22.4+/-4.9; 24.5+/-5.5 cm at 30, 60, and 90 days, respectively) in comparison with baseline (52.9+/-5.2 cm; P<0.05). At 60 and 90 days, bCCA-o rats in comparison with sham-operated rats showed decreased performances on object recognition (discrimination index: 0.15+/-0.03 vs. 0.29+/-0.05 at 60 days and 0.10+/-0.04 vs. 0.41+/-0.07 at 90 days; P<0.05) and on Y maze test (alternating rats: 9.9 vs. 85.7% at 60 days and 16.6 vs. 100% at 90 days; P<0.01). In none of the animals were cerebral infarcts detected. Selective neuronal necrosis was observed in the cortex and hippocampus of both bCCA-o and sham-operated rats without any obvious difference.

CONCLUSIONS

bCCA-o in the Wistar rat induces persistent and progressive gait and working memory impairment without producing sensorimotor deficit or cerebral infarcts. This model may help to elucidate some physiopathological aspects of neurological impairment associated with states of cerebral chronic ischemia.

Ageing of the brain

The brains of individuals who are cognitively normal show age-related changes that include an overall reduction in the brain volume and weight and enlargement of the brain ventricles. These changes are partly the result of nerve cell loss but accurate estimates of neuronal loss are notoriously difficult to make. There is loss of synapses and dendritic pruning in the aged brain but in selected areas rather than globally. Neurofibrillary tangles and senile plaques are the neuropathological hallmark of Alzheimer's disease in which they are more abundant and widespread than in the brains of intellectually intact elderly people. Alzheimer's disease has, therefore, been regarded as accelerated brain ageing, however, since there is a strong genetic contribution to developing the disease it implies that it may not be the inevitable, even if frequent, consequence of old age. The interplay between genetic and environmental factors probably determines the degree of pathological brain ageing and whether or not individuals develop dementia.

Diffuse white matter changes caused by dural arteriovenous fistula

We present two patients with progressive dementia who showed diffuse white matter changes on magnetic resonance imaging (MRI) associated with dural arteriovenous fistula (DAVF) involving the transverse-sigmoid sinuses. Angiography of both patients revealed that DAVF was associated with multiple occlusive changes in the dural venous sinus. The associated occlusive changes isolated the straight sinus and the DAVF from the other venous sinuses, and concentrated the drainage of the DAVF in the straight sinus. We postulate that the venous hypertension of the straight sinus resulted in the venous ischemia of the white matter, diffuse white matter changes on MRI, and progressive neurological signs including dementia. Treatment of the DAVF reversed white matter changes and neurological signs. Associated with the venous sinus occlusions, the DAVF caused dementia with diffuse white matter changes due to the venous ischemia.

Dural arteriovenous malformation manifesting as dementia due to ischemia in bilateral thalami. A case report

BACKGROUND

Although dementia is one of the curable manifestations of a dural arteriovenous malformation (AVM), the pathophysiology remains unclear.

CASE DESCRIPTION

We describe an elderly patient who had an AVM in the tentorium and manifested signs of dementia from ischemia, predominantly in the bilateral thalami. Intravascular embolization of the dural AVM resulted in amelioration of signs of dementia, and this improvement was consistent with that of neuroradiological and hemodynamic conditions in the thalami.

CONCLUSION

The coincidental improvement of CBF in the thalami and signs of dementia after embolization of the AV shunt supports the concept of primary participation of the thalami in the pathophysiology of dementia of vascular origin in our patient.

Intracranial dural arteriovenous fistula (DAVF) presenting progressive dementia and parkinsonism

We studied three patients with dural arteriovenous fistula (DAVF). Major symptoms were progressive dementia and parkinsonism, both of which progressed in step-wise fashion. Two of the three patients showed diffuse cerebral white matter lesions on brain CT and MRI. Progressive dementia and parkinsonism in our patients could be caused by diffuse cerebral parenchymal disturbance: impaired cerebral circulation due to severe venous hypertension. DAVF is important for the differential diagnosis in patients with progressive dementia and parkinsonism.

Positron emission tomography in vascular dementia

BACKGROUND

Vascular dementia (VaD) is an ill-defined entity. It is not known how acute brain failure related to stroke becomes chronic leading to dementia.

PURPOSE

The present study investigates whether positron emission tomography (PET) can detect different metabolic patterns in VaD.

PATIENTS AND METHODS

Four groups of stroke patients were selected. The PET findings of 14 stroke patients with multiple large infarcts and dementia (MID) and 14 without dementia (MS) were compared. Sixteen stroke patients with lacunes, leukoaraiosis and dementia (LD) were assessed against nine without dementia (LS). The PET examination utilised the 15-O-steady-state technique in order to determine regional cerebral blood flow (rCBF), regional oxygen extraction rate (rOER) and regional cerebral metabolic rate for oxygen (rCMRO2) in different pre-established cortical, subcortical and cerebellar regions.

RESULTS

Decreased coupled mean rCBF and rCMRO2 with comparable rOER values were observed in all cerebral regions except in the cerebellum of the MID compared to the MS group. In the LD group mean rCBF and rCMRO2 were decreased with increased rOER in all cerebral regions except in the cerebellum compared to the LS group.

CONCLUSIONS

The PET findings in demented patients with multiple large infarcts are in agreement with the concept of multi-infarct dementia. In demented patients with lacunes and leukoaraiosis, the PET pattern suggests a state of misery perfusion not only in the deep structures but also in the whole cerebral cortex. The present PET study argues that there are at least two possible mechanisms that can explain the occurrence of VaD in stroke patients.

Changes in the ageing brain in health and disease

The brains of individuals, who are cognitively normal, show age-related changes that include an overall reduction in brain volume and weight, which are associated with gyral atrophy and widening of the sulci of the cerebral cortex, and enlargement of the brain ventricles. These changes are partly the result of nerve cell loss but accurate estimates of neuronal loss are notoriously difficult to make. Microscopically, there are increasing amounts of the age-related pigment, lipofuscin, granulovacuolar degeneration in neurones, Hirano bodies, variable amounts of diffuse deposits of beta-amyloid in the parenchyma, the presence of neurofibrillary tangles mainly confined to the hippocampus and amygdala, and sparse numbers of senile plaques in these brain regions and also in other cortical areas. Of these changes, neurofibrillary tangles and senile plaques are the neuropathological hallmark of Alzheimer's disease in which they are more abundant and widespread. Alzheimer's disease has therefore been regarded as accelerated brain ageing; however, the realization that there is a strong genetic contribution to developing the disease at least implies that it may not be the inevitable, even if frequent, consequence of old age. Understanding the molecular basis of plaque and tangle formation is advancing greatly and is the main focus of research into the cellular and molecular changes observed in the ageing brain.

Three-vessel study of cerebral blood flow using phase-contrast magnetic resonance imaging: effect of physical characteristics

The development of phase-contrast magnetic resonance imaging (P-C MRI) provides a noninvasive method for measurement of volumetric blood flow (VFR). We performed P-C MRI to study the effects of physical characteristics on cerebral blood flow. VFR of the left and right internal carotid arteries and basilar artery were measured using P-C MRI and total cerebral blood flow (tCBF) was calculated by summing up the VFR values in the three vessels. Moreover, we investigated the changes in these blood flows as influenced by age, head size, height, weight, body surface area, and handedness. The blood flows were 142 +/- 58 ml/min (mean +/- standard deviation) in the basilar artery; and 229 +/- 86 ml/min in the left, and 223 +/- 58 ml/min in the right internal carotid artery; and tCBF was 617 +/- 128 ml/min. Significant increases were observed in head size-related change of VFR in the basilar artery (p = .028) and height-related change of tCBF (p = .045). The other characteristics did not significantly influence any VFR. The results suggest that head size and height may reflect CBF, and that these effects should be considered when changes of CBF are diagnosed. Phase-contrast MRI is useful for a noninvasive and rapid analysis of cerebral VFR and has potential for clinical use.

Progressive neurologic impairment from an arteriovenous malformation vascular steal

Approximately 15% of all cerebral arteriovenous malformations (AVMs) present with progressive neurologic deficits, the pathogenic mechanism of which has not been established. One suggestion is that AVMs by expanding over time compress normal surrounding cerebral parenchyma and thereby cause progressive neurologic impairment. Alternatively, a vascular steal results in progressive ischemia of normal cerebral tissue. Because the area occupied by the AVM and the area of observed blood flow reductions in all reported patients have overlapped, delineating the relative contribution of local compression from that of vascular steal has not been possible. We present a 7-month-old girl and a 7-year-old boy with AVMs restricted to the diencephalon who had progressive cognitive impairment and dystrophic cerebral hemispheral calcification (in the 7-month-old girl) indicating diffuse cerebral cortical involvement remote from the AVM. These patients provide evidence for vascular steal, and not local compression, as the primary mechanism underlying a progressive neurologic course associated with some AVMs.