Severely impaired cerebrovascular reserve in patients with cerebral proliferative angiopathy

Cerebral proliferative angiopathy in pediatric age presenting as neurological disorders: A case report

BACKGROUND

Cerebral proliferative angiopathy (CPA) is a rare subtype of arteriovenous malformation. It is extremely rare in pediatric patients and has serious implications for developing children. However, reports of these disorders worldwide are limited, and no uniform reference for diagnosis and treatment options exists. We report the case of a 6-year-old with CPA having predominantly neurological dysfunction and review the literature on pediatric CPA.

CASE SUMMARY

We report the case of a pediatric patient with CPA analyzed using digital subtraction angiography (DSA) who presented initially with a neurological disorder as the main manifestation. This case is the basis for further discussion of the clinical presentation, pathogenesis, diagnosis, and treatment of CPA in children. After the cerebral DSA, the patient was treated conservatively with sedation, fluid replacement, and blood anticoagulation. She could not cooperate with the follow-up magnetic resonance imaging examination because of her young age, and her family declined further treatment because of the surgery’s high risk. She was followed up for 3 months; her symptoms did not worsen.

CONCLUSION

This report of rare pediatric CPA can inform and advance clinical research on congenital cerebrovascular diseases.

Recurrent Intraventricular Haemorrhage in Cerebral Proliferative Angiopathy - A Case Report and Review of the Literature

Cerebral proliferative angiopathy (CPA) is an entity distinct from that of classical arteriovenous malformations. As such, few reports have considered the long-term follow-up of patients with hemorrhage in CPA. Accordingly, herein the authors present a case of recurrent hemorrhage in CPA with 32 years of follow-up and in so doing summarize the literature of hemorrhagic cases in CPA. A 19-year-old presented with focal awareness seizures and diagnostic work-up revealed a left hemispheric vascular lesion. The patient presented again with intracranial hemorrhage at ages 28, 43 and 51. Angioarchitectural workup revealed intermingled brain parenchyma between vascular spaces, absence of dominant feeders and a clear nidus consistent with CPA. The size and diffuse nature of the lesion deemed it inoperable. Given our case and review of the literature it is apparent that CPA has a high risk of re-hemorrhage in the rare event that hemorrhage does occur.

Diffuse cerebral angiomatosis associated to basilar apex aneurysm

BACKGROUND

Diffuse cerebral angiomatosis (DCA) is a diffuse infiltration of normal brain by complex vascular structures. It differs from arteriovenous malformations (AVMs) that are composed of a nidus of vessels through which arteriovenous shunting occurs without interposed functional brain parenchyma. A rare subgroup of AVMs is diffuse with no recognizable nidus with functional neuronal tissue interspersed within the malformed vessels. We present a rare association of DCA and cerebral arterial aneurysm, which dramatically influenced the patient's prognosis.

CASE DESCRIPTION

A 43-year-old male patient with right hemispheric diffuse cerebral angiomatosis presented with a ruptured basilar tip aneurysm that was successfully embolised. Unfortunately, the patient developed a locked-in syndrome.

CONCLUSION

The present report shows a possible association between diffuse cerebral angiomatosis and cerebral aneurysms, but this association appears to be less strong than it is with other AVMs.

A Proposed Algorithm for Managing Cerebral Proliferative Angiopathy

OBJECTIVE

Cerebral proliferative angiopathy (CPA) is a rare disease, characterized by a large vascular nidus, diffuse angiogenesis, and intermingled normal brain tissue. Conservative treatment, endovascular intervention, indirect revascularization, and radiotherapy have been applied to treat this disease. However, some cases deteriorate even after non-conservative treatment, and there has been no standard of treatment for this disease so far. In order to build a better treatment strategy, we review literature, present our case and propose an algorithm for managing CPA.

METHODS

Following the PRISMA principle, we systemically reviewed literature discussing CPA. A case successfully managed with multi-modal treatment is also illustrated.

RESULTS

A total of 23 articles with 74 cases of CPA were found. Thirty-three patients received single-modal management. These 33 cases include 24 receiving endovascular intervention, 7 receiving indirect revascularization, and 2 receiving radiotherapy. Three of the 33 patients deteriorated clinically, and 1 expired. We present a 6-year-old boy with left hemispheric CPA receiving indirect revascularization, followed by 2 consecutive courses of stereotactic radiosurgery targeting arteriovenous shunts in the left basal ganglia and arteriovenous shunts around the olfactory groove. In the follow-up period of more than 4 years, good collateral formation, improved perilesional perfusion, CPA shrinkage, and symptom relief were all achieved.

CONCLUSIONS

Based on our literature review and case, we propose an algorithm for the management of CPA and emphasize that multi-modal treatment is necessary for most CPA cases.

More pronounced hemodynamic alterations in patients with brain arteriovenous malformation–associated epilepsy

OBJECTIVE

Epileptic seizures in patients with brain arteriovenous malformations (bAVMs) may be caused by hemodynamic alterations due to the complex angioarchitecture of bAVMs. In particular, an arterial steal phenomenon and venous outflow disruption may play an etiological role in seizure development but remain challenging to demonstrate quantitatively. Blood oxygenation level–dependent (BOLD) cerebrovascular reactivity (CVR) imaging is an emerging technique that can measure both arterial steal phenomenon (as a paradoxical BOLD signal decrease during a vasodilatory stimulus) and impaired perinidal BOLD-CVR (which has been found in the presence of venous congestion on conventional angiography in bAVM patients with epilepsy). By applying this innovative BOLD-CVR technique, the aim is to better study CVR patterns and their correlation with morphological features on conventional angiography in patients with bAVM with and without epilepsy.

METHODS

Twenty-two patients with unruptured and previously untreated bAVMs (8 with and 14 without epilepsy) were included in this case-control study. Quantitative CVR measurements were derived from BOLD functional MRI volumes using a novel standardized and precise hypercapnic stimulus (i.e., % BOLD/mm Hg CO2). In addition, 22 matched healthy controls underwent an identical BOLD-CVR study. Evaluation of venous congestion was performed on conventional angiography for all patients with bAVM.

RESULTS

Patients with bAVM-associated epilepsy showed impaired whole-brain BOLD-CVR compared to those in the nonepilepsy group, even after correction for AVM volume and AVM grade (epilepsy vs nonepilepsy group: 0.17 ± 0.07 vs 0.25 ± 0.07, p = 0.04). A BOLD-CVR–derived arterial steal phenomenon was observed in 2 patients with epilepsy (25%). Venous congestion was noted in 3 patients with epilepsy (38%) and in 1 patient without epilepsy (7%; p = 0.08).

CONCLUSIONS

These data suggest that whole-brain CVR impairment, and more pronounced hemodynamic alterations (i.e., arterial steal phenomenon and venous outflow restriction), may be more present in patients with bAVM-associated epilepsy. The association of impaired BOLD-CVR and bAVM-associated epilepsy will need further investigation in a larger patient cohort.

Cerebral Proliferative Angiopathy Presenting as Subdural Hematoma: A Case Report and Systematic Literature Review

Cerebral proliferative angiopathy (CPA) is a rare cerebrovascular pathology that presents with unique clinical features due to distinct histologic, angiographic, and pathophysiologic characteristics that separate it from classical arteriovenous malformation. The disorder is characterized by uncontrolled angiogenesis in which functional brain parenchyma is interspersed with abnormal vascular channels without a distinct nidus. Common presenting symptoms include headache, seizures, and stroke-like symptoms. Hemorrhagic presentations are rare in contrast to the typical presentations of classical arteriovenous malformation. Here, we report a young woman with a history of a suspected connective tissue disorder who presented to the emergency department with worsening headaches in a delayed fashion after experiencing minor head trauma and was found to have a left-sided subdural hematoma. Angiography confirmed a diagnosis of CPA after abnormal cortical vasculature was noted during the patient's craniotomy. A systematic review of CPA cases described in the literature was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, with the findings discussed.

Hemorrhagic cerebral proliferative angiopathy in two pediatric patients: case reports

Cerebral proliferative angiopathy (CPA) is an infrequent vascular malformation. It is composed of a nidus, arterial feeders, and venous drainage. Some special features differentiate it from the common arteriovenous malformations (AVM). The nidus has normal cerebral tissue intermingled and occupies a large portion of the brain. There is a frequent transdural arterial supply. Arterial feeders and draining veins are of small caliber concerning the nidus size. Ischemic strokes are the most common clinical event. Intracranial bleeding when occurs has a worse prognosis due to its high recurrence rate. We have presented two cases of CPA in pediatric patients who required surgical resolution of their acute episode.

Microsurgical Treatment of Deep and Eloquent AVMs

Over the past 30 years, the treatment of deep and eloquent arteriovenous malformations (AVMs) has moved away from microneurosurgical resection and towards medical management and the so-called minimally invasive techniques, such as endovascular embolization and radiosurgery. The Spetzler-Martin grading system (and subsequent modifications) has done much to aid in risk stratification for surgical intervention; however, the system does not predict the risk of hemorrhage nor risk from other interventions. In more recent years, the ARUBA trial has suggested that unruptured AVMs should be medically managed. In our experience, although these eloquent regions of the brain should be discussed with patients in assessing the risks and benefits of intervention, we believe each AVM should be assessed based on the characteristics of the patient and the angio-architecture of the AVM, in particular venous hypertension, which may guide us to treat even high-grade AVMs when we believe we can (and need to) to benefit the patient. Advances in imaging and intraoperative adjuncts have helped us in decision making, preoperative planning, and ensuring good outcomes for our patients. Here, we present several cases to illustrate our primary points that treating low-grade AVMs can be more difficult than treating high-grade ones, mismanagement of deep and eloquent AVMs at the behest of dogma can harm patients, and the treatment of any AVM should be tailored to the individual patient and that patient's lesion.

A rare case of cerebral proliferative angiopathy with acute cerebral infarction and facial capillary malformation

We are describing a case of a 14-year-old girl who developed acute cerebral infarction which was documented on diffusion-weighted magnetic resonance imaging (DWI). On detailed evaluation, diagnosis of cerebral proliferative angiopathy (CPA) was made. Incidentally, she had capillary malformation on the forehead contralateral to cerebral vascular malformation. To our knowledge, this is the first case of CPA in the literature where DWI abnormality was due to acute cerebral infarction.

Cerebrovascular Reactivity Measurement Using Magnetic Resonance Imaging: A Systematic Review

Cerebrovascular reactivity (CVR) magnetic resonance imaging (MRI) probes cerebral haemodynamic changes in response to a vasodilatory stimulus. CVR closely relates to the health of the vasculature and is therefore a key parameter for studying cerebrovascular diseases such as stroke, small vessel disease and dementias. MRI allows in vivo measurement of CVR but several different methods have been presented in the literature, differing in pulse sequence, hardware requirements, stimulus and image processing technique. We systematically reviewed publications measuring CVR using MRI up to June 2020, identifying 235 relevant papers. We summarised the acquisition methods, experimental parameters, hardware and CVR quantification approaches used, clinical populations investigated, and corresponding summary CVR measures. CVR was investigated in many pathologies such as steno-occlusive diseases, dementia and small vessel disease and is generally lower in patients than in healthy controls. Blood oxygen level dependent (BOLD) acquisitions with fixed inspired CO₂ gas or end-tidal CO₂ forcing stimulus are the most commonly used methods. General linear modelling of the MRI signal with end-tidal CO₂ as the regressor is the most frequently used method to compute CVR. Our survey of CVR measurement approaches and applications will help researchers to identify good practice and provide objective information to inform the development of future consensus recommendations.

The current clinical picture of cerebral proliferative angiopathy: systematic review

BACKGROUND

Cerebral proliferative angiopathy (CPA) is a rare subset of arteriovenous malformations (AVM). It has unique clinical presentation, angiographic characteristics, and pathophysiology which often brings challenges for the treatment. We aimed to define its epidemiology, pathophysiology are unknown, and best management strategies.

METHODS

A systematic review was conducted according to the PRISMA guidelines. MEDLINE was searched for articles regarding CPA. Extracted data included epidemiological, clinical, and angiographical characteristics, treatment, and outcomes. Treatment was classified as conservative, radiosurgery, endovascular, decompression, and indirect vascularization. A meta-analytical approach was employed for description of the data as study-size adjusted percentages or weighted means, as appropriate.

RESULTS

Thirty-three studies were analyzed, rendering a total 95 cases-half of which came from a single study. Patients were predominantly young (mean 23 years old) and female (60.0%) presenting with headaches (44.9%), seizures (37.1%), or transient ischemic attacks (33.7%). Hemorrhage was present in 18.0%, but rebleeding rates were as high as 67%. The majority of nidus were > 6 cm (52.5%) with hemispheric extension (73.0%). Capillary angioectatic appearance (85.7%), transdural supply (62.5%), and deep venous drainage (73.0%) were also frequent features. Most patients were treated conservatively (54.4%), followed by endovascular (34.2%). Indirect vascularization and radiosurgery were attempted in five and two patients, respectively. Mean follow-up was 110.8 patient-years. Neurological status improved in 50.7%, remained stable in 40.2%, and worsened in 9.0%.

CONCLUSIONS

Conservative and endovascular treatments seem adequate interventions, despite limited evidence. Complementary techniques can be used in patients throughout disease history, according to symptom-based, individualized approach. More studies are required for choosing interventions based on reliable long-term results.

Pediatric cerebral proliferative angiopathy presenting infratentorial hemorrhage

Cerebral proliferative angiopathies (CPAs) are distinct vascular malformations with varied clinical presentations and radiological findings from arteriovenous malformations (AVM) (Lasjaunias et al. in Stroke 39(3):878-85, 2008). They usually manifest with seizures if present supratentorial, headache, and progressive neurological deficits due to steal phenomenon or rarely with hemorrhage (Lasjaunias et al. in Stroke 39(3):878-85, 2008). Most of the patients are usually young females. Pediatric cases are extremely rare, with few cases reported till now. Here we report a child who presented with cerebellar bleed and diagnosed as CPA. The child was managed medically, and there was no change in caliber of the vessels after 18 months of follow-up. A short review of cases of CPA in pediatric age group presentations and management was undertaken in this case report.

Feasibility of improving cerebral autoregulation in acute intracerebral hemorrhage (BREATHE-ICH) study: Results from an experimental interventional study

Background

Cerebral autoregulation is impaired in a multitude of neurological conditions. Increasingly, clinical studies are correlating the nature of this impairment with prognostic markers. In acute intracerebral hemorrhage, impairment of cerebral autoregulation has been associated with worsening clinical outcomes including poorer Glasgow Coma Score and larger hematoma volume. Hypocapnia has been shown to improve cerebral autoregulation despite concerns over hypoperfusion and consequent ischemic risks, and it is therefore hypothesized that hypocapnia (via hyperventilation) in acute intracerebral hemorrhage may improve cerebral autoregulation and consequently clinical outcome.

Aims

To assess the feasibility and acceptability of the first cerebral autoregulation-targeted intervention in acute intracerebral hemorrhage utilizing a simple bed-side hyperventilatory maneuver.

Methods

Twelve patients with acute intracerebral hemorrhage within 48 h of onset were enrolled. The experimental setup measured cerebral blood flow velocity (transcranial Doppler), blood pressure (Finometer), and end-tidal CO2 (EtCO2, capnography) at baseline, and in response to hypocapnia (−5 mmHg below baseline) achieved via a 90-s hyperventilatory maneuver. Cerebral autoregulation was evaluated with transfer function analysis and autoregulatory index calculations.

Results

We observed tolerance to the protocol in a cohort of mild (National Institutes of Health Scale 4) supratentorial intracerebral hemorrhage patients with small volume hematomas without intraventricular extension. Importantly, a significant difference was noted between ipsilateral autoregulatory index at baseline 4.8 (1.7) and autoregulatory index during hypocapnic intervention 7.0 (0.8) (p = 0.0004), reflecting improved cerebral autoregulation, though a dose-dependent effect of EtCO2 on autoregulatory index was not observed.

Conclusions

In this small study, there was no observed effect on 14-day death and disability in recruited participants. This is the first report of improvement in cerebral autoregulation in acute intracerebral hemorrhage using a non-invasive interventional maneuver, through induction of hypocapnia via hyperventilation. ClinicalTrials.gov Identifier: NCT03324321 URL: https://clinicaltrials.gov/ct2/show/NCT03324321

The voxel-wise analysis of false negative fMRI activation in regions of provoked impaired cerebrovascular reactivity

Task-evoked Blood-oxygenation-level-dependent (BOLD-fMRI) signal activation is widely used to interrogate eloquence of brain areas. However, data interpretation can be improved, especially in regions with absent BOLD-fMRI signal activation. Absent BOLD-fMRI signal activation may actually represent false-negative activation due to impaired cerebrovascular reactivity (BOLD-CVR) of the vascular bed. The relationship between impaired BOLD-CVR and BOLD-fMRI signal activation may be better studied in healthy subjects where neurovascular coupling is known to be intact. Using a model-based prospective end-tidal carbon dioxide (CO₂) targeting algorithm, we performed two controlled 3 tesla BOLD-CVR studies on 17 healthy subjects: 1: at the subjects’ individual resting end-tidal CO₂ baseline. 2: Around +6.0 mmHg CO₂ above the subjects’ individual resting baseline. Two BOLD-fMRI finger-tapping experiments were performed at similar normo- and hypercapnic levels. Relative BOLD fMRI signal activation and t-values were calculated for BOLD-CVR and BOLD-fMRI data. For each component of the cerebral motor-network (precentral gyrus, postcentral gyrus, supplementary motor area, cerebellum und fronto-operculum), the correlation between BOLD-CVR and BOLD-fMRI signal changes and t-values was investigated. Finally, a voxel-wise quantitative analysis of the impact of BOLD-CVR on BOLD-fMRI was performed. For the motor-network, the linear correlation coefficient between BOLD-CVR and BOLD-fMRI t-values were significant (p<0.01) and in the range 0.33–0.55, similar to the correlations between the CVR and fMRI Δ%signal (p<0.05; range 0.34–0.60). The linear relationship between CVR and fMRI is challenged by our voxel-wise analysis of Δ%signal and t-value change between normo- and hypercapnia. Our main finding is that BOLD fMRI signal activation maps are markedly dampened in the presence of impaired BOLD-CVR and highlights the importance of a complementary BOLD-CVR assessment in addition to a task-evoked BOLD fMRI to identify brain areas at risk for false-negative BOLD-fMRI signal activation.

Cerebral revascularization in cerebral proliferative angiopathy: a systematic review

OBJECTIVE

Cerebral proliferative angiopathy (CPA) is considered a discrete vascular malformation of the brain separate from classical brain arteriovenous malformations (AVMs). It has unique angiographic characteristics and has been hypothesized to result from chronic cortical ischemia and perinidal oligemia. Treatment with cerebral revascularization has been proposed in an attempt to disrupt regional hypoperfusion and interrupt the angiogenesis that defines CPA. A systematic review of the literature pertaining to the role of cerebral revascularization may highlight a treatment paradigm for this rare disease.

METHODS

A systematic review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. MEDLINE and Embase were searched from inception for papers relating to CPA. Included articles were categorized according to methodology (case series or imaging study) and treatment modality (conservative, radiation, endovascular, or revascularization). A synthesis was compiled summarizing the current evidence regarding cerebral revascularization in CPA.

RESULTS

The initial search revealed 43 articles, of which 28 studies met the inclusion criteria. Nine studies were identified that described imaging findings, which suggested hemodynamic dysregulation and perinidal impairments in the cerebrovascular reserve could be identified compared to unaffected hemispheres and classical brain AVMs. Six studies including 7 patients undergoing indirect forms of cerebral revascularization were identified. Clinical and radiological outcomes following revascularization were favorable in all but one study.

CONCLUSIONS

A small body of radiological and clinical studies has emerged, suggesting that CPA is a response to perinidal oligemia. While the long-term clinical efficacy of revascularization remains unclear, early results suggest that this may be a novel treatment paradigm for patients with CPA.

A Novel Stress-Diathesis Model to Predict Risk of Post-operative Delirium: Implications for Intra-operative Management

Introduction: Risk assessment for post-operative delirium (POD) is poorly developed. Improved metrics could greatly facilitate peri-operative care as costs associated with POD are staggering. In this preliminary study, we develop a novel stress-diathesis model based on comprehensive pre-operative psychiatric and neuropsychological testing, a blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) carbon dioxide (CO₂) stress test, and high fidelity measures of intra-operative parameters that may interact facilitating POD. Methods: The study was approved by the ethics board at the University of Manitoba and registered at clinicaltrials.gov as NCT02126215. Twelve patients were studied. Pre-operative psychiatric symptom measures and neuropsychological testing preceded MRI featuring a BOLD MRI CO₂ stress test whereby BOLD scans were conducted while exposing participants to a rigorously controlled CO₂ stimulus. During surgery the patient had hemodynamics and end-tidal gases downloaded at 0.5 hz. Post-operatively, the presence of POD and POD severity was comprehensively assessed using the Confusion Assessment Measure -Severity (CAM-S) scoring instrument on days 0 (surgery) through post-operative day 5, and patients were followed up at least 1 month post-operatively. Results: Six of 12 patients had no evidence of POD (non-POD). Three patients had POD and 3 had clinically significant confusional states (referred as subthreshold POD; ST-POD) (score ≥ 5/19 on the CAM-S). Average severity for delirium was 1.3 in the non-POD group, 3.2 in ST-POD, and 6.1 in POD (F-statistic = 15.4, p < 0.001). Depressive symptoms, and cognitive measures of semantic fluency and executive functioning/processing speed were significantly associated with POD. Second level analysis revealed an increased inverse BOLD responsiveness to CO₂ pre-operatively in ST-POD and marked increase in the POD groups when compared to the non-POD group. An association was also noted for the patient population to manifest leucoaraiosis as assessed with advanced neuroimaging techniques. Results provide preliminary support for the interacting of diatheses (vulnerabilities) and intra-operative stressors on the POD phenotype. Conclusions: The stress-diathesis model has the potential to aid in risk assessment for POD. Based on these initial findings, we make some recommendations for intra-operative management for patients at risk of POD.

Feasibility of Flat Panel Detector CT in Perfusion Assessment of Brain Arteriovenous Malformations: Initial Clinical Experience

The different results from flat panel detector CT in various pathologies have provoked some discussion. Our aim was to assess the role of flat panel detector CT in brain arteriovenous malformations, which has not yet been assessed. Five patients with brain arteriovenous malformations were studied with flat panel detector CT, DSC-MR imaging, and vessel-encoded pseudocontinuous arterial spin-labeling. In glomerular brain arteriovenous malformations, perfusion was highest next to the brain arteriovenous malformation with decreasing values with increasing distance from the lesion. An inverse tendency was observed in the proliferative brain arteriovenous malformation. Flat panel detector CT, originally thought to measure blood volume, correlated more closely with arterial spin-labeling-CBF and DSC-CBF than with DSC-CBV. We conclude that flat panel detector CT perfusion depends on the time point chosen for data collection, which is triggered too early in these patients (ie, when contrast agent appears in the superior sagittal sinus after rapid shunting through the brain arteriovenous malformation). This finding, in combination with high data variability, makes flat panel detector CT inappropriate for perfusion assessment in brain arteriovenous malformations.

Development of Abnormal Hemispheric Vascular Networks Mimicking Cerebral Proliferative Angiopathy in a Child Originally Diagnosed with Deep-Seated Arteriovenous Fistula

Cerebral proliferative angiopathy (CPA), which is characterized by diffuse vascular abnormalities with intermingled normal brain parenchyma, is a rare clinical entity distinct from classical cerebral arteriovenous malformations. Its pathology at initial state and subsequent course of progression has totally been undetermined. We herein presented a case of a child who was initially diagnosed with deep-seated arteriovenous fistula (AVF), and ultimately developed symptomatic CPA-like vascular lesion over a long period of clinical follow-up. A 7-month-old boy was incidentally found to have an AVF in the right basal ganglia and conservatively followed up. Serial magnetic resonance angiograms revealed the gradual proliferation and enlargement of pial and medullary vessels surrounding the AVF. Seven years later, he had a transient ischemic attack followed by intraventricular hemorrhage. A catheter angiogram showed a diffuse large vascular malformation composed of 2 distinct structures, including AVF in the right basal ganglia and the surrounding proliferated pial and medullary arteries in the right hemisphere. Single-photon emission computed tomography with N-isopropyl[123I]-p-iodoamphetamine revealed apparent hemodynamic compromise on the right hemisphere. Targeted embolization of the pseudoaneurysm originating from the right A1 perforator was performed to prevent rebleeding without complications. The patient had no further cerebrovascular events. Perinidal hypoperfusion induced by a deep-seated AVF could be one of the underlying pathologies of progressive angiogenic activity. This is the first case showing the development of abnormal hemispheric vascular networks mimicking CPA, which offers insight into the pathogenesis of this new entity.

Neuroimaging Assessment of Cerebrovascular Reactivity in Concussion: Current Concepts, Methodological Considerations, and Review of the Literature

Concussion is a form of traumatic brain injury (TBI) that presents with a wide spectrum of subjective symptoms and few objective clinical findings. Emerging research suggests that one of the processes that may contribute to concussion pathophysiology is dysregulation of cerebral blood flow (CBF) leading to a mismatch between CBF delivery and the metabolic needs of the injured brain. Cerebrovascular reactivity (CVR) is defined as the change in CBF in response to a measured vasoactive stimulus. Several magnetic resonance imaging (MRI) techniques can be used as a surrogate measure of CBF in clinical and laboratory studies. In order to provide an accurate assessment of CVR, these sequences must be combined with a reliable, reproducible vasoactive stimulus that can manipulate CBF. Although CVR imaging currently plays a crucial role in the diagnosis and management of many cerebrovascular diseases, only recently have studies begun to apply this assessment tool in patients with concussion. In order to evaluate the quality, reliability, and relevance of CVR studies in concussion, it is important that clinicians and researchers have a strong foundational understanding of the role of CBF regulation in health, concussion, and more severe forms of TBI, and an awareness of the advantages and limitations of currently available CVR measurement techniques. Accordingly, in this review, we (1) discuss the role of CVR in TBI and concussion, (2) examine methodological considerations for MRI-based measurement of CVR, and (3) provide an overview of published CVR studies in concussion patients.

Cerebral proliferative angiopathy: Clinical, angiographic features and literature review

PURPOSE

Here we present our experience with five cerebral proliferative angiopathy (CPA) patients to better delineate the clinical and angiographic features as well as the treatment selection of this disease.

METHODS

Between October 2008 and October 2012, five consecutive patients diagnosed with CPA were admitted to our department in our hospital. All the five patients received magnetic resonance imaging, digital subtraction angiography, and positron emission computed tomography (PET) to definitively confirm this disease. We also collected 15 previously published instances of CPA to analyze the characteristics of this rare entity.

RESULTS

As to the five patients, three were female and two were male, between the ages of 4 and 52 years with a mean age of 24.8±20.6 years. The PET results showed that perfusion was decreased over the affected hemispheres in all five patients. As to the treatment, only one patient received encephalo-duro-arterio-synangiosis (EDAS) revascularization surgery. The other four patients were conservatively observed. During the follow-up period (range 3-6 years, mean 4±1.9 years), the patient who underwent EDAS surgery manifested relief of clinical symptoms. In the conservative series, the symptoms in two patients aggravated and suffered permanent neurologic deficits.

CONCLUSION

CPA is a rare entity. Natural history has showed this disease is not stable and may progress at a certain time point. The EDAS procedure may be a treatment for CPA-related oligemia since there is currently little data and follow-up available.

On the optimization of imaging protocol for the mapping of cerebrovascular reactivity

BACKGROUND

To devise an improved blood-oxygen-level-dependent (BOLD) imaging protocol for cerebrovascular reactivity (CVR) measurement that can remove a known artifact of negative values.

METHODS

Theoretical and simulation studies were first performed to understand the biophysical mechanism of the negative CVR signals, through which improved BOLD sequence parameters were proposed. This was achieved by equating signal intensities between cerebrospinal fluid and blood, by means of shortening the echo time (TE) of the BOLD sequence. Then, 10 healthy volunteers were recruited to participate in an experimental study, in which we compared the CVR results of two versions of the optimized ("Opt1" and "Opt2") protocols with that of the standard protocol at 3 Tesla. Two sessions were performed for each subject to test the reproducibility of all three protocols.

RESULTS

Experimental results demonstrated that the optimized protocols resulted in elimination of negative-CVR voxels. Quantitative CVR results were compared across protocols, which show that the optimized protocols yielded smaller CVR values (Opt1: 0.16 ± 0.01 %BOLD/mmHg CO2 ; Opt2: 0.15 ± 0.01 %BOLD/mmHg CO2 ) than (P < 0.001) the standard protocol (0.21 ± 0.01 %BOLD/mmHg CO2 ), but the CNR was comparable (P = 0.1) to the standard protocol. The coefficient-of-variation between repetitions was found to be 5.6 ± 1.4%, 6.3 ± 1.6%, and 6.9 ± 0.9% for the three protocols, but there were no significant differences (P = 0.65).

CONCLUSION

Based on the theoretical and experimental results obtained from this study, we suggest that the use of a TE shorter than those used in fMRI is necessary to minimize negative artifact in CVR results.

Encephaloduroarteriosynangiosis for cerebral proliferative angiopathy with cerebral ischemia

Cerebral proliferative angiopathy (CPA) is a rare clinical entity. This disorder is characterized by diffuse vascular abnormalities with intermingled normal brain parenchyma, and is differentiated from classic arteriovenous malformations. The management of CPA in patients presenting with nonhemorrhagic neurological deficits due to cerebral ischemia is challenging and controversial. The authors report a case of adult CPA with cerebral ischemia in which neurological deficits were improved after encephaloduroarteriosynangiosis (EDAS). A 28-year-old man presented with epilepsy. Magnetic resonance imaging and angiography showed a diffuse vascular network (CPA) in the right hemisphere. Antiepileptic medications were administered. Four years after the initial onset of epilepsy, the patient's left-hand grip strength gradually decreased over the course of 1 year. The MRI studies showed no infarcts, but technetium-99m-labeled ethyl cysteinate dimer ((99m)Tc-ECD) SPECT studies obtained with acetazolamide challenge demonstrated hypoperfusion and severely impaired cerebrovascular reactivity over the affected hemisphere. This suggested that the patient's neurological deficits were associated with cerebral ischemia. The authors performed EDAS for cerebral ischemia, and the patient's hand grip strength gradually improved after the operation. Follow-up angiography studies obtained 7 months after the operation showed profound neovascularization through the superficial temporal artery and the middle meningeal artery. A SPECT study showed slight improvement of hypoperfusion at the focal region around the right motor area, indicating clinical improvement from the operation. The authors conclude that EDAS may be a treatment option for CPA-related hypoperfusion.

Functional imaging of cerebral perfusion

The functional imaging of perfusion enables the study of its properties such as the vasoreactivity to circulating gases, the autoregulation and the neurovascular coupling. Downstream from arterial stenosis, this imaging can estimate the vascular reserve and the risk of ischemia in order to adapt the therapeutic strategy. This method reveals the hemodynamic disorders in patients suffering from Alzheimer's disease or with arteriovenous malformations revealed by epilepsy. Functional MRI of the vasoreactivity also helps to better interpret the functional MRI activation in practice and in clinical research.

Acute hemiparesis in a child as a presenting symptom of hemispheric cerebral proliferative angiopathy

A 9-year-old girl with a several-month history of unilateral intermittent headaches presented to the hospital with worsening headaches and unsteadiness. Neurologic exam was positive for a mild right hemiparesis and right homonymous hemianopsia. Noncontrast computed tomography revealed an engorged sagittal and straight sinus with prominent cortical veins concerning an arteriovenous malformation and the patient was admitted to the pediatric intensive care unit. Computed tomography angiogram demonstrated a left hemispheric vascular malformation, without evidence of dural arteriovenous fistula on conventional angiogram consistent with a diagnosis of cerebral proliferative angiopathy. There was no evidence of infarct on magnetic resonance imaging, and the patient's symptoms were completely resolved within 24 hours. Cerebral proliferative angiopathy is a rare but important vascular malformation distinct from classic arteriovenous malformations that may present with stroke-like symptoms in childhood.

CO2 blood oxygen level-dependent MR mapping of cerebrovascular reserve in a clinical population: safety, tolerability, and technical feasibility

PURPOSE

To evaluate the safety, tolerability, and technical feasibility of mapping cerebrovascular reactivity (CVR) in a clinical population by using a precise prospectively targeted CO(2) stimulus and blood oxygen level-dependent (BOLD) magnetic resonance (MR) imaging.

MATERIALS AND METHODS

A chart review was performed of all CVR studies from institutional review board-approved projects at a tertiary care hospital between January 1, 2006, and December 1, 2010. Informed consent was obtained. Records were searched for the incidence of adverse events and failed examinations. CVR maps were evaluated for diagnostic quality by two blinded observers and were categorized as good, diagnostic but suboptimal, or nondiagnostic. Outcomes were presented as raw data and descriptive statistics (means ± standard deviations). Intraclass correlation coefficient was used to determine interobserver variability.

RESULTS

Four hundred thirty-four consecutive CVR examinations from 294 patients (51.8% female patients) were studied. Patient age ranged from 9 to 88 years (mean age, 45.9 years ± 20.6). Transient symptoms, such as shortness of breath, headache, and dizziness, were reported in 48 subjects (11.1% of studies) during hypercapnic phases only. There were no neurologic ischemic events, myocardial infarctions, or other major complications. The success rate in generating CVR maps was 83.9% (364 of 434). Of the 70 (16.1%) failed examinations, 25 (35.7%) were due to discomfort; eight (11.4%), to head motion; two (2.9%), to inability to cooperate; seven (10.0%), to technical difficulties with equipment; and 28 (40.0%), to unknown or unspecified conditions. Among the 364 remaining successful examinations, good quality CVR maps were obtained in 340 (93.4%); diagnostic but suboptimal, in 12 (3.3%); and nondiagnostic, in 12 (3.3%).

CONCLUSION

CVR mapping by using a prospectively targeted CO(2) stimulus and BOLD MR imaging is safe, well tolerated, and technically feasible in a clinical patient population.