The Cerebrovascular Side of Plasticity: Microvascular Architecture across Health and Neurodegenerative and Vascular Diseases.

The delivery of nutrients to the brain is provided by a 600 km network of capillaries and microvessels. Indeed, the brain is highly energy demanding and, among a total amount of 100 billion neurons, each neuron is located just 10-20 µm from a capillary. This vascular network also forms part of the blood-brain barrier (BBB), which maintains the brain's stable environment by regulating chemical balance, immune cell transport, and blocking toxins. Typically, brain microvascular endothelial cells (BMECs) have low turnover, indicating a stable cerebrovascular structure. However, this structure can adapt significantly due to development, aging, injury, or disease. Temporary neural activity changes are managed by the expansion or contraction of arterioles and capillaries. Hypoxia leads to significant remodeling of the cerebrovascular architecture and pathological changes have been documented in aging and in vascular and neurodegenerative conditions. These changes often involve BMEC proliferation and the remodeling of capillary segments, often linked with local neuronal changes and cognitive function. Cerebrovascular plasticity, especially in arterioles, capillaries, and venules, varies over different time scales in development, health, aging, and diseases. Rapid changes in cerebral blood flow (CBF) occur within seconds due to increased neural activity. Prolonged changes in vascular structure, influenced by consistent environmental factors, take weeks. Development and aging bring changes over months to years, with aging-associated plasticity often improved by exercise. Injuries cause rapid damage but can be repaired over weeks to months, while neurodegenerative diseases cause slow, varied changes over months to years. In addition, if animal models may provide useful and dynamic in vivo information about vascular plasticity, humans are more complex to investigate and the hypothesis of glymphatic system together with Magnetic Resonance Imaging (MRI) techniques could provide useful clues in the future.

Endovascular therapy in patients with acute intracranial non-terminal internal carotid artery occlusion (ICA-I).

BACKGROUND: Acute intracranial occlusion of the internal carotid artery (ICA) can be distinguished into (a) occlusion of the terminal ICA, involving the proximal segments of the middle or anterior cerebral artery (ICA-L/-T) and (b) non-terminal intracranial occlusions of the ICA with patent circle of Willis (ICA-I). While patients with ICA-L/-T occlusion were included in all randomized controlled trials on endovascular therapy (EVT) in anterior large vessel occlusion, data on EVT in ICA-I occlusion is scarce. We thus aimed to evaluate effectiveness and safety of EVT in ICA-I occlusions in comparison to ICA-L/-T occlusions. METHODS: A large international multicentre cohort was searched for patients with intracranial ICA occlusion treated with EVT between 2014 and 2023. Patients were stratified by ICA occlusion pattern, differentiating ICA-I and ICA-L/-T occlusions. Baseline factors, technical (modified thrombolysis in cerebral infarction (mTICI) scale) and functional outcomes (modified Rankin scale [mRS] at 3 months) as well as rates of (symptomatic) intracranial hemorrhage ([s]ICH) were analyzed. RESULTS: Of 13,453 patients, 1825 (13.6%) had isolated ICA occlusion. ICA-occlusion pattern was ICA-I in 559 (4.2%) and ICA-L/-T in 1266 (9.4%) patients. Age (years: 74 vs 73), sex (female: 45.8% vs 49.0%) and pre-stroke functional independency (pre-mRS ⩽ 2: 89.9% vs 92.2%) did not differ between the groups. Stroke severity was lower in ICA-I patients (NIHSS at admission: 14 [7-19] vs 17 [13-21] points). EVT was similarly successful with respect to technical (mTICI2b/3: 76.1% (ICA-I) vs 76.6% (ICA-L/-T); aOR 1.01 [0.76-1.35]) and functional outcome (mRS ordinal shift cOR 1.01 [0.83-1.23] in adjusted analyses. Rates of ICH (18.9% vs 34.5%; aOR 0.47 [0.36-0.62] and sICH (4.7% vs 7.3%; aOR 0.58 [0.35-0.97] were lower in ICA-I patients. CONCLUSION: EVT might be performed safely and similarly successful in patients with ICA-I occlusions as in patients with ICA-L/-T occlusions.

Type III Percheron's variant in thalamic-mesencephalic infarction: the unexpected anastomosis.

PURPOSE: Arterial supply of thalamus is complex and highly variable. In particular, the distribution pattern of thalamoperforating arteries received more attention some decades ago than in recent years. METHODS: We are presenting the case of a 46-year-old patient with wake-up drowsiness, complex oculomotor disorder and dysarthria. He was investigated in the acute phase using non-contrast brain Computed Tomography (NCCT), CT Angiography (CTA), and in the following days Digital Subtraction Angiography (DSA) was performed Results. The NCCT showed a subacute ischemic stroke in the right anterior thalamus and rostral midbrain with normal findings on CTA. DSA imaged a variant of thalamic supply (Percheron type III), constituted by perforating branches arising from an artery bridging the P1 segments of both Posterior Cerebral Arteries (PCAs). RESULTS: The thalamus has a complex and variable arterial supply, mainly in the pattern of paramedian thalamic-mesencephalic perforating arteries. The most reported variant is Percheron type IIb and supplies the paramedian thalami and the rostral midbrain. Type IIb occlusion usually causes a bilateral paramedian thalamic stroke, but rostral midbrain and anterior thalamus are involved in 57% and 19% cases. The rarer Type III variant probably prevented the bilateral extension of infarction and involved the territory of tuberothalamic and paramedian perforating arteries. CONCLUSIONS: Currently, DSA allows directly imaging variants in thalamic vascularization and better understanding the stroke mechanisms. In particular, in the presented case, a medium-sized vessel occlusion rather than a small vessel occlusion mechanism might be raised, leading to a different diagnostic pathway.

Two novel compound heterozygous HOXB1 variants in congenital facial palsy: A case report and a brief review of the literature.

Hereditary congenital facial palsy (HCFP) is a medical condition caused by dysfunction of the seventh cranial nerve. HCFP is characterized by feeding difficulties and dysmorphic features in the orofacial region. In some cases hearing loss, strabismus, limb malformations, and musculoskeletal defects may be associated. There are three types of HCFP: HCFP3 (OMIM 614744) results from autosomal recessive pathogenic variants in the HOXB1 gene, while HCFP1 and 2 (OMIM 601471, 604185) are autosomal dominant, genetically less defined conditions. We report on a case of congenital bilateral facial palsy due to two novel compound heterozygous variants in the HOXB1 gene, found by exome sequencing (ES), in a child with facial nerve axonal neuropathy without evidence of nerve hypoplasia on neuroimaging. The results of this report suggest that in individuals with congenital facial paralysis and preserved ocular motor skills, with or without facial nerve hypoplasia and with confirmed facial nerve axonal neuropathy, HOXB1 variants and therefore a diagnosis of HCFP3 should be primarily considered.

Acute Encephalopathies in SARS-CoV-2 Infection: A Clinical and Neuroimaging Perspective.

Neurological manifestations are frequent in patients with SARS-CoV-2 infection and can be correlated with different pathogenic mechanisms which can be divided into two categories: direct invasion of the central nervous system by the virus and indirect effects deriving from the severity of the systemic infection and by the inflammatory response correlated with cytokine storm. Among the neurological manifestations, acute encephalopathy is very frequent and its nomenclature has recently been updated. The occurrence of a condition of altered mental status, reduced consciousness, delirium up to coma represents an element associated with a greater severity of the infection and mortality both in an Intensive Care Unit setting and in an Emergency Department setting. The tissue damage mechanisms found in COVID-19 patients' encephalopathy and neuroimaging patterns, as well as histopathology, are similar to those described in sepsis-associated encephalopathy, further confirming the role of indirect mechanisms, with no CNS invasion by the virus. The available data have some limitations, notably the underuse of diagnostic neuroimaging techniques in severely affected patients, particularly in the first wave of the pandemic.

Pathophysiology of COVID-19-Related Extrapyramidal Disorders.

Coronavirus disease 2019 (COVID-19) has been associated with a variety of neurological manifestations (i.e., anosmia, ageusia, myalgia, headache) and neurological syndromes (i.e., encephalopathy, ischemic and hemorrhagic stroke, myelitis, encephalitis) underlying different pathogenetic mechanisms. COVID-19 has also been associated with various movement disorders including acute or subacute parkinsonism. However, to date, only few cases of parkinsonism linked to COVID-19 have been reported, nevertheless raising the possibility of a post-viral parkinsonian syndrome. Furthermore, various studies in vitro and in animal models have highlighted a close relationship between SARS-CoV-2 virus and α-synuclein, leading to the hypothesis that COVID-19 could represent a factor favoring the long-term development of α-synucleopathies. In this chapter, we will discuss the pathophysiological mechanisms related to movement disorders' manifestations of COVID-19 focusing on the possible overlap between pathogenetic mechanisms of Parkinson's Disease and COVID-19.

Spontaneous Non-Aneurysmal Convexity Subarachnoid Hemorrhage: A Scoping Review of Different Etiologies beyond Cerebral Amyloid Angiopathy.

Spontaneous convexity subarachnoid hemorrhage (cSAH) is a vascular disease different from aneurysmal SAH in neuroimaging pattern, causes, and prognosis. Several causes might be considered in individual patients, with a limited value of the patient's age for discriminating among these causes. Cerebral amyloid angiopathy (CAA) is the most prevalent cause in people > 60 years, but reversible cerebral vasoconstriction syndrome (RCVS) has to be considered in young people. CAA gained attention in the last years, but the most known manifestation of cSAH in this context is constituted by transient focal neurological episodes (TFNEs). CAA might have an inflammatory side (CAA-related inflammation), whose diagnosis is relevant due to the efficacy of immunosuppression in resolving essudation. Other causes are hemodynamic stenosis or occlusion in extracranial and intracranial arteries, infective endocarditis (with or without intracranial infectious aneurysms), primary central nervous system angiitis, cerebral venous thrombosis, and rarer diseases. The diagnostic work-up is fundamental for an etiological diagnosis and includes neuroimaging techniques, nuclear medicine techniques, and lumbar puncture. The correct diagnosis is the first step for choosing the most effective and appropriate treatment.

Rare neurovascular variants that you probably have not seen before.

BACKGROUND: Recognition of neurovascular variants is crucial for safe endovascular and neurosurgical interventions. We aim to review and highlight various uncommon neurovascular variants and anomalies with a discussion of their relevant embryology and pathology. METHODS: A retrospective review of a prospectively maintained neurovascular database was performed to identify uncommon neurovascular variants and anomalies. A pictorial review of these neurovascular findings is provided along with relevant embryological development, clinical significance, and potential pathological associations. RESULTS: A pictorial review of selected neurovascular variants and anomalies is presented. These entities, divided between intra- and extra-cranial findings, include infra-optic origin of the anterior cerebral artery, meningo-ophtalmic artery, duplicated posterior cerebral artery, duplicate middle cerebral artery (MCA), MCA fenestration, twig-like MCA, pure arterial malformation, corkscrew basilar artery, persistent hypoglossal artery, persistent trigeminal artery and its variants, direct branches from the common carotid and cervical internal carotid arteries (ICA) (ascending pharyngeal artery from the ICA, thyroidal arteries from the CCA/brachiocephalic, arteria thyroidea ima), and extra-cranial carotid fenestration. The angiographic findings of these entities are presented with relevant 3D reconstruction and multimodal cross-sectional imaging correlation when available. CONCLUSIONS: This pictorial review highlights uncommon neurovascular variants and anomalies that neuroradiologists, interventionalists, and neurosurgeons should be aware of for accurate diagnosis and safe interventions.

Contrast-Induced Encephalopathy: A Case Series Analysis.

BACKGROUND: Contrast-induced encephalopathy (CIE) is a rare adverse event linked to intravascular use of iodine-containing contrast media. The prevalence of CIE could increase in the future due to growing numbers of endovascular procedures. We provide insights from a case series of 7 patients. METHODS: Cases from 3 centers were collected based on existing academic collaborations, and key factors were extracted to illustrate development and management of CIE. RESULTS: In our retrospective case-series analysis of 7 cases from 3 countries, affected patients had an equal distribution of sex (4 women, 3 men) and a median age of 75 (IQR 63-77). Common risk factors included hypertension (5/7), hyperlipidemia (5/7), previous stroke (3/7), and type 2 diabetes (3/7). CIE developed in 3 cases after endovascular thrombectomy (EVT) for stroke, in 2 cases after aneurysm treatment, in 1 case after cardiac catheterization, and in 1 case after diagnostic computed tomography (CT) angiography without an endovascular procedure. The median procedure time was 48 min (IQR 40-81). All patients received non-ionic, low-osmolar contrast agents with volumes ranging from 100-300 ml. Symptom onset was close to contrast administration, with stroke-like neurological deficits being most common (4/7). Prednisolone was the most frequently used medication to treat the symptoms (4/7). Symptom resolution occurred in 4 out of 7 patients within two to several days, and 1 patient died, but without clear connection to CIE. CONCLUSION: CIE is a rare and possibly underrecognized condition, but fortunately, with a favorable outcome in most cases.

Neurovascular Issues in Antiphospholipid Syndrome: Arterial Vasculopathy from Small to Large Vessels in a Neuroradiological Perspective.

Antiphospholipid syndrome (APS) is an autoimmune prothrombotic condition characterized by venous thromboembolism, arterial thrombosis, and pregnancy morbidity. Among neurological manifestations, arterial thrombosis is only one of the possible associated clinical and neuroradiological features. The aim of this review is to address from a neurovascular point of view the multifaceted range of the arterial side of APS. A modern neurovascular approach was proposed, dividing the CNS involvement on the basis of the size of affected arteries, from large to small arteries, and corresponding clinical and neuroradiological issues. Both large-vessel and small-vessel involvement in APS were detailed, highlighting the limitations of the available literature in the attempt to derive some pathomechanisms. APS is a complex disease, and its neurological involvement appears multifaceted and not yet fully characterized, within and outside the diagnostic criteria. The involvement of intracranial large and small vessels appears poorly characterized, and the overlapping with the previously proposed inflammatory manifestations is consistent.

Expanding the Neurological Phenotype of Anderson-Fabry Disease: Proof of Concept for an Extrapyramidal Neurodegenerative Pattern and Comparison with Monogenic Vascular Parkinsonism.

Anderson-Fabry disease (AFD) is a genetic sphingolipidosis involving virtually the entire body. Among its manifestation, the involvement of the central and peripheral nervous system is frequent. In recent decades, it has become evident that, besides cerebrovascular damage, a pure neuronal phenotype of AFD exists in the central nervous system, which is supported by clinical, pathological, and neuroimaging data. This neurodegenerative phenotype is often clinically characterized by an extrapyramidal component similar to the one seen in prodromal Parkinson's disease (PD). We analyzed the biological, clinical pathological, and neuroimaging data supporting this phenotype recently proposed in the literature. Moreover, we compared the neurodegenerative PD phenotype of AFD with a classical monogenic vascular disease responsible for vascular parkinsonism and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). A substantial difference in the clinical and neuroimaging features of neurodegenerative and vascular parkinsonism phenotypes emerged, with AFD being potentially responsible for both forms of the extrapyramidal involvement, and CADASIL mainly associated with the vascular subtype. The available studies share some limitations regarding both patients' information and neurological and genetic investigations. Further studies are needed to clarify the potential association between AFD and extrapyramidal manifestations.

RNF213 Polymorphisms in Intracranial Artery Dissection.

The ring finger protein 213 gene (RNF213) is involved in several vascular diseases, both intracranial and systemic ones. Some variants are common in the Asian population and are reported as a risk factor for moyamoya disease, intracranial stenosis and intracranial aneurysms. Among intracranial vascular diseases, both moyamoya disease and intracranial artery dissection are more prevalent in the Asian population. We performed a systematic review of the literature, aiming to assess the rate of RNF213 variants in patients with spontaneous intracranial dissections. Four papers were identified, providing data on 53 patients with intracranial artery dissection. The rate of RNF213 variants is 10/53 (18.9%) and it increases to 10/29 (34.5%), excluding patients with vertebral artery dissection. All patients had the RNF213 p.Arg4810Lys variant. RNF213 variants seems to be involved in intracranial dissections in Asian cohorts. The small number of patients, the inclusion of only patients of Asian descent and the small but non-negligible coexistence with moyamoya disease familiarity might be limiting factors, requiring further studies to confirm these preliminary findings and the embryological interpretation.

Statin use and long-term risk of recurrent intracerebral haemorrhage: the MUCH-Italy.

BACKGROUND: Whether statin use after spontaneous intracerebral haemorrhage (ICH) increases the risk of recurrent ICH is uncertain. METHODS: In the setting of the Multicentric Study on Cerebral Haemorrhage in Italy we followed up a cohort of 30-day ICH survivors, consecutively admitted from January 2002 to July 2014, to assess whether the use of statins after the acute event is associated with recurrent cerebral bleeding. RESULTS: 1623 patients (mean age, 73.9±10.3 years; males, 55.9%) qualified for the analysis. After a median follow-up of 40.5 months (25th to 75th percentile, 67.7) statin use was not associated with increased risk of recurrent ICH either in the whole study group (adjusted HR, 0.99; 95% CI 0.64 to 1.53) or in the subgroups defined by haematoma location (deep ICH, adjusted HR, 0.74; 95% CI 0.35 to 1.57; lobar ICH, adjusted HR, 1.09; 95% CI 0.62 to 1.90), intensity of statins (low-moderate intensity statins, adjusted HR, 0.93; 95% CI 0.58 to 1.49; high-intensity statins, adjusted HR, 1.48; 95% CI 0.66 to 3.31) and use of statins before the index event (adjusted HR, 0.66; 95% CI 0.38 to 1.17). CONCLUSIONS: Statin use appears to be unrelated to the risk of ICH recurrence.

Reperfusion therapies in patients with acute ischaemic stroke and atrial fibrillation: data on safety and effectiveness from a multi-centre cohort study.

BACKGROUND: Intravenous thrombolysis (IVT) and/or endovascular therapy (EVT) are currently considered best practices in acute stroke patients. Data regarding the efficacy and safety of reperfusion therapies in patients with atrial fibrillation (AF) are conflicting as regards haemorrhagic transformation, mortality, and functional outcome. This study sought to investigate for any differences, in terms of safety and effectiveness, between AF patients with acute ischaemic stroke (AIS) treated and untreated with reperfusion therapies. METHODS: Data from two multicenter cohort studies (RAF and RAF-NOACs) on consecutive patients with AF and AIS were analyzed to compare patients treated and not treated with reperfusion therapies (IVT and/or EVT). Multivariable logistic regression analysis was performed to identify independent predictors for outcome events: 90-day good functional outcome and mortality. A propensity score matching (PSM) analysis compared treated and untreated patients. RESULTS: Overall, 441 (25.4%) were included in the reperfusion-treated group and 1,295 (74.6%) in the untreated group. The multivariable model suggested that reperfusion therapies were significantly associated with good functional outcome. Rates of mortality and disability were higher in patients not treated, especially in the case of higher NIHSS scores. In the PSM comparison, 173/250 patients (69.2%) who had received reperfusion therapies had good functional outcome at 90 days, compared to 146/250 (58.4%) untreated patients (p = 0.009, OR: 1.60, 95% CI:1.11-2.31). CONCLUSIONS: Patients with AF and AIS treated with reperfusion therapies had a significantly higher rate of good functional outcome and lower rates of mortality compared to those patients with AF and AIS who had undergone conservative treatment.

Persistent intracranial steno-occlusion from calcified embolism: a treatment challenge.

INTRODUCTION: Calcified arterial cerebral embolism is a rare occurrence among large and medium vessel occlusions causing ischemic stroke and its diagnosis and treatment is a challenge. The sources of calcified embolism might be a calcific atheroma from the aortic arch and carotid artery, but also heart valve disease has been reported in the literature. Calcified embolism is frequently simultaneous on multiple vascular territories. The prognosis of patients is usually poor, including patients treated by using endovascular thrombectomy (EVT) and this diagnosis could be easily missed in the acute phase. In addition, the optimal secondary prevention has not been yet fully stated. METHODS: We are presenting two cases of acute stroke due to calcified embolism in the middle cerebral artery (MCA) coming from a complicated carotid atheroma, non-stenosing in the first case (a 49 years old man) and stenosing in the second case (a 71 years old man) without clinical indications to intravenous thrombolysis and/or EVT, extensively investigated in the acute phase and followed-up for over 12 months with a favorable clinical course and the persisting steno-occlusion in the involved MCA. In both cases, antiplatelet treatment and targeting of vascular risk factors were done without recurrences in the follow-up period. DISCUSSION: Cerebral calcified embolism has been reported in 5.9% of cases of acute ischemic stroke in a single center series and only in 1.2% of a large retrospective cohort of EVT-treated patients. In both series the prognosis was poor and only one third of EVT-treated patients had functional independence at 3-months follow-up. The natural history of these subtype of ischemic stroke is relatively poorly understood and both etiological diagnosis and treatment have not yet defined. It is possible that some cases might be underdiagnosed and underreported. CONCLUSIONS: Calcified cerebral embolism is a rare cause of stroke, but it is largely underreported and both acute phase and secondary preventive treatment have to be defined.

Cerebellar mutism syndrome caused by bilateral cerebellar hemorrhage in adults: a case report and review of the literature.

Cerebellar mutism syndrome (CMS) is a frequent complication of surgical intervention on posterior fossa in children. It has been only occasionally reported in adults and its features have not been fully characterized. In children and in young adults, medulloblastoma is the main reason for neurosurgery. A single case of postsurgical CMS is presented in an adult patient with a cerebellar hemorrhage and a systematic review of the published individual cases of CMS in adults was done. Literature review of individual cases found 30 patients, 18/30 (60%) males, from 20 to 71 years at diagnosis. All but one case was post-surgical, but in one of the post-surgical cases iatrogenic basilar artery occlusion was proposed as cause for CMS. The causes were: primary tumors of the posterior fossa in 16/22 (72.7%) metastasis in 3/30 (10%), ischemia in 3/30 (10%) cerebellar hemorrhage in 3/30 (10%), and benign lesions in 2/30 (6.7%) patients. 8/30 patients (26.7%) were reported as having persistent or incomplete resolution of CMS within 12 months. CMS is a rare occurrence in adults and spontaneous cerebellar hemorrhage has been reported in 3/30 (10%) adult patients. The generally accepted hypothesis is that CMS results from bilateral damage to the dentate nucleus or the dentate-rubro-thalamic tract, leading to cerebro-cerebellar diaschisis. Several causes might contribute in adults. The prognosis of CMS is slightly worse in adults than in children, but two thirds of cases show a complete resolution within 6 months.

Characteristics and outcomes of cerebral venous thrombosis associated with COVID-19.

INTRODUCTION: Previous reports and meta-analyses derived from small case series reported a mortality rate of up to 40% in patients with coronavirus disease 2019 associated cerebral venous thrombosis (COVID-CVT). We assessed the clinical characteristics and outcomes in an international cohort of patients with COVID-CVT. PATIENTS AND METHODS: This was a registry study of consecutive COVID-CVT patients diagnosed between March 2020 and March 2023. Data collected by the International Cerebral Venous Thrombosis Consortium from patients with CVT diagnosed between 2017 and 2018 served as a comparison. Outcome analyses were adjusted for age and sex. RESULTS: We included 70 patients with COVID-CVT from 23 hospitals in 15 countries and 206 controls from 14 hospitals in 13 countries. The proportion of women was smaller in the COVID-CVT group (50% vs 68%, p < 0.01). A higher proportion of COVID-CVT patients presented with altered mental state (44% vs 25%, p < 0.01), the median thrombus load was higher in COVID-CVT patients (3 [IQR 2-4] vs 2 [1-3], p < 0.01) and the length of hospital stay was longer compared to controls (11 days [IQR 7-20] vs 8 [4-15], p = 0.02). In-hospital mortality did not differ (5/67 [7%, 95% CI 3-16] vs 7/206 [3%, 2-7], aOR 2.6 [95% CI 0.7-9]), nor did the frequency of functional independence after 6 months (modified Rankin Scale 0-2; 45/58 [78%, 95% CI 65-86] vs 161/185 [87%, 81-91], aOR 0.5 [95% CI 0.2-1.02]). CONCLUSION: In contrast to previous studies, the in-hospital mortality rate and functional outcomes during follow-up did not differ between COVID-CVT patients and the pre-COVID-19 controls.