Bilateral intracranial vertebral artery disease in the New England Medical Center, Posterior Circulation Registry

Rescue Endovascular Treatment to Prevent Neurological Deterioration in Acute Symptomatic Bilateral Vertebral Artery Occlusion

Bilateral vertebral artery occlusive disease has been considered as a favorable condition with good collaterals. However, the prognosis of acute ischemic stroke secondary to symptomatic bilateral vertebral artery occlusion (BVAO) and endovascular treatment (EVT) has rarely been reported. We retrospectively selected patients with acute ischemic stroke admitted for symptomatic BVAO between January 2020 and February 2023. All patients with ischemic stroke were evaluated for ischemic lesion and arterial status using brain imaging and angiography. The prognosis of acute stroke with symptomatic BVAO was compared between EVT and conventional treatment. Outcomes were evaluated using modified Rankin Scale (mRS) score at 3 months follow-up. Within the study period, 17 of 2,655 acute ischemic stroke patients were diagnosed with ischemic stroke with symptomatic BVAO. The median age of these patients was 70 (interquartile range 44-89) years, and 13 (76%) were male. Seven patients received emergent EVT with stenting and 10 patients received conventional medical treatment only. Nine of 10 patients with conventional treatment had in-hospital stroke progression and developed new ischemic lesions in the pons and midbrain. Five patients with fetal and hypoplastic posterior communicating artery presented bilateral cerebral peduncular lesions. At 3 months follow-up, 6 patients (35%) had favorable outcomes (mRS 0-2), of which 5 were treated with vertebral artery stenting and 1 received conventional treatment. Ischemic stroke in patients with acute symptomatic BVAO is uncommon. However, stroke progression is common, and the prognosis of most patients is poor. Rescue management such as EVT might be considered for symptomatic BVAO.

Subintimal recanalization for non-acute occlusion of intracranial vertebral artery in an emergency endovascular procedure: A case report

BACKGROUND

Endovascular recanalization of non-acute intracranial artery occlusion is technically difficult, particularly when the microwire enters the subintima. Although the subintimal tracking and re-entry technique has been well established in the endovascular treatment of coronary artery occlusion, there is limited experience with its use in intracranial occlusion due to anatomical variations and a lack of dedicated devices.

CASE SUMMARY

A 74-year-old man was admitted to the hospital two days after experiencing acute weakness in both lower extremities, poor speech, and dizziness. After admission, imaging revealed acute ischemic stroke and non-acute occlusion of bilateral intracranial vertebral arteries (ICVAs). On the fourth day of admission, the patient's condition deteriorated and an emergency endovascular recanalization of the left ICVA was performed. During this procedure, a microwire was advanced in the subintima of the vessel wall and successfully reentered the distal true lumen. Two stents were implanted in the subintima. The patient's Modified Rankin Scale was 1 at three months postoperatively.

CONCLUSION

We present a technical case of subintimal recanalization for non-acute ICVA occlusion in an emergency endovascular procedure. However, we emphasize the necessity for caution when applying the subintimal tracking approach in intracranial occlusion due to the significant dangers involved.

Case Report: Double Micro-Guidewire Technique for Emergent Rescue of Proximal Stent Collapse During Recanalization of Nonacute Occlusion of Vertebral Artery

Cerebral arteries are usually tortuous, and in the treatment of cerebrovascular diseases with stenting, a stent deployed may be collapsed at one end, leading to reduced blood flow and subsequent stent occlusion. Immediate rescuing measures should be implemented to prevent severe ischemic events. In this case report, we present a case with V4 segment occlusion of the right vertebral artery treated with endovascular stent angioplasty. An Enterprise stent deployed at the occlusion segment was collapsed at the proximal end after withdrawal of the delivery system. Immediate rescuing measures were taken by navigating a micro-guidewire through the lateral stent mesh at the proximal end into the stent lumen followed by advancing a second micro-guidewire right through the reopened proximal stent end into the stent lumen for deployment of a supporting balloon-expandable Apollo stent to prevent stent collapse. Follow-up digital subtraction angiography 6 months later demonstrated patent stents and unobstructed blood flow.

Gravitational effects on intracranial pressure and blood flow regulation in young men: a potential shunting role for the external carotid artery

We sought to determine whether gravity-induced changes in intracranial pressure influence cerebral blood flow regulation. Accordingly, nine young healthy men were studied while supine (0°) and during mild changes in hydrostatic pressure induced by head-up tilt at +20° and +10° (HUT+20 and HUT+10) and head-down tilt at -20° and -10° (HDT-20, HDT-10). Blood flows were measured in the internal and external carotid and vertebral arteries (ICA, ECA, and VA). Intraocular pressure (IOP) was measured as an indicator of hydrostatic changes in intracranial pressure. A posture change from HUT+20 to HDT-20 increased IOP by +5.1 ± 1.9 mmHg (P < 0.001) and ECA blood flow (from 61.7 ± 26.1 to 87.6 ± 46.4 mL/min, P = 0.004) but did not affect ICA (P = 0.528) or VA (P = 0.101) blood flow. The increase in ECA flow correlated with the tilt angle and resultant changes in intracranial pressures (by IOP), thus indicating a passive hydrostatic gravitational dependence (r = 0.371, P = 0.012). On the contrary, ICA flow remained constant and thus well protected against moderate orthostatic stress. When ICA flow was corrected for the gravitational changes in intracranial pressures (by IOP), it demonstrated the same magnitude of gravitational dependence as ECA. These findings suggest that passive hydrostatic increases in intracranial pressure outbalance the concurrent increase in arterial feeding pressure to the brain and thus prevent cerebral hyperperfusion during HDT. The mechanism for maintaining constant cerebral flow was by increased ECA flow, thus supporting the role of these vascular beds as a shunting pathway.NEW & NOTEWORTHY We investigated whether gravity-induced changes in intracranial pressure influence cerebral blood flow regulation in young men. We recorded extra- and intracerebral blood flow during changes in posture, and data indicate that the external carotid artery may serve as an overflow pathway to prevent cerebral hyperperfusion during increases in cerebral arterial blood pressure.

Lesion Topography and Its Correlation With Etiology in Medullary Infarction: Analysis From a Multi-Center Stroke Study in China

Objectives: The lesion topography of medullary infarction (MI) is heterogeneous and its correlation with stroke etiology remains elusive. We aim to clarify the lesion pattern of MI and to assess its correlation with stroke etiology.

Material and Methods: Of 1129 subjects with available DWI in SMART study (a multi-center trial concerning secondary stroke prevention in China) between April 2008 and December 2010, 43 patients with DWI confirmed MI (3.8%) were retrospectively evaluated. Lesions were categorized as lateral and medial medullary infarction (LMI and MMI, 33 and 10 subjects respectively) at 3 levels rostro-caudally and correlated with the stroke etiology. Clinical profiles and long-term prognosis were analyzed.

Results: Large artery atherosclerosis, small vessel occlusion, cardiogenic embolism and artery dissection accounted for 29, 11, 1, and 2 infarcts, respectively. Large artery disease was the most common cause in LMI (24 of 33, 72.7%) whereas small vessel occlusion was not uncommon in MMI (5 of 10, 50.0%). Though the difference of infarct pattern between large artery atherosclerosis and small vessel occlusion was insignificant, two distinct lesion patterns were considered to be relevant: (1) Rostral MMI with continuous medial pontine infarctions were more likely attributed to small vessel occlusion than large artery atherosclerosis. Kameda et al. (2) MMI with ventral to dorsal extension were more often caused by large artery disease than small vessel occlusion. Median NIHSS at admission was 4. During a median follow-up of 17 months, 2 patients died and 2 experienced recurrent ischemic events, 39 of 41 subjects (95.1%) were functional independent (mRS 0–2).

Conclusions: This multi-center study demonstrates that MI has distinct lesion pattern depending on various stroke etiologies and mechanisms. Future investigations with larger sample size should establish the lesion pattern of MI and validate its correlation with the stroke etiology and mechanisms, which might improve stroke management.

Sodium nitroprusside dilates cerebral vessels and enhances internal carotid artery flow in young men

KEY POINTS

Sodium nitroprusside lowers blood pressure by vasodilatation but is reported to reduce cerebral blood flow. In healthy young men sodium nitroprusside reduced blood pressure, total peripheral resistance, and arterial CO₂ tension and yet cerebral blood flow was maintained, with an increase in internal carotid artery blood flow and cerebrovascular conductance. Sodium nitroprusside induces both systemic and cerebral vasodilatation affecting internal carotid artery more than vertebral artery flow.

ABSTRACT

Cerebral autoregulation maintains cerebral blood flow (CBF) despite marked changes in mean arterial pressure (MAP). Sodium nitroprusside (SNP) reduces blood pressure by vasodilatation but is reported to lower CBF, probably by a reduction in its perfusion pressure. We evaluated the influence of SNP on CBF and aimed for a 20% and then 40% reduction in MAP, while keeping MAP ≥ 50 mmHg, to challenge cerebral autoregulation. In 19 healthy men (age 24 ± 4 years; mean ± SD) duplex ultrasound determined right internal carotid (ICA) and vertebral artery (VA) blood flow. The SNP reduced MAP (from 83 ± 8 to 69 ± 8 and 58 ± 4 mmHg; both P < 0.0001), total peripheral resistance, and arterial CO₂ tension (P aC O2; 41 ± 3 vs. 39 ± 3 and 37 ± 4 mmHg; both P < 0.01). Yet ICA flow increased with the moderate reduction in MAP but returned to the baseline value with the large reduction in MAP (336 ± 66 vs. 365 ± 69; P = 0.013 and 349 ± 82 ml min^-1 ; n.s.), while VA flow (114 ± 34 vs. 112 ± 38 and 110 ± 42 ml min^-1 ; both n.s.) and CBF ((ICA + VA flow) × 2; 899 ± 135 vs. 962 ± 127 and 918 ± 197 ml min^-1 ; both n.s.) were maintained with increased cerebrovascular conductance. In conclusion, CBF is maintained during SNP-induced reduction in MAP despite reduced P aC O2 and the results indicate that SNP dilates cerebral vessels and increases ICA flow.

Endovascular recanalization for chronic symptomatic intracranial vertebral artery total occlusion: Experience of a single center and review of literature

OBJECTIVE

The optimal treatment of chronic symptomatic total occlusion of the intracranial vertebral artery (ICVA) remains undefined. We report a single-center experience of endovascular recanalization for patients with chronic symptomatic ICVA occlusion who were refractory to medical therapy.

METHODS

From Jan 2009 to Jan 2017, we retrospectively reviewed 14 consecutive patients presenting with recurrent symptoms attributed to the chronic ICVA occlusion. We searched previous literature using PubMed databases during the same period as comparison.

RESULTS

Eleven patients out of 14 presented initial symptoms to intervention less than 90days. The occlusion course was extrapolated on simultaneous two-vessel injection angiography or high-resolution MR imaging (HRMRI) in 13 cases. Nine patients had the occlusion beyond the origin of posterior inferior cerebellar artery (PICA) and 5 had the occlusion proximal to the PICA origin. The technical success rate of recanalization was 85.7% (12/14). Two patients (14.3%, 2/14) had peri-procedural complications: 1 developed TIA and 1 presented with perforator occlusion syndrome. Using the keyword-based search, we identified 6 studies at the same period. A total of 34 patients underwent recanalization with the successful recanalization rate at 94.1%, peri-procedural complication rate at 17.6% and mortality at 2.9%, respectively.

CONCLUSION

Our single-center study illustrated the feasibility and safety of ICVA recanalization. Great care should be taken as revascularization is of high risk. When patient selection, occlusion course and stage as well as neuroimaging evaluation are considered, endovascular recanalization may be a useful therapeutic modality.

The Number of Stenotic Intracranial Arteries Is Independently Associated with Ischemic Stroke Severity

Background

The severity of ischemic stroke symptoms varies among patients and is a critical determinant of patient outcome. To date, the association between the number of stenotic intracranial arteries and stroke severity remains unclear.

Aims

We aimed to investigate the association between the number of stenotic major intracranial arteries (NSMIA) and ischemic stroke severity, as well as the degree of stenosis and common stroke risk factors.

Methods

We performed a retrospective analysis of patients with digital subtraction angiography (DSA)-confirmed ischemic stroke. Clinical stroke severity was measured using the National Institutes of Health Stroke Scale (NIHSS). The number of stenotic vessels was counted from the internal carotid arteries and vertebral arteries, bilaterally.

Results

Eighty three patients were recruited from a single center and included in the study. NSMIA was significantly correlated with stroke severity (Pearson Correlation Coefficient = 0.485, P < 0.001), but not with the degree of stenosis (Pearson Correlation Coefficient = 0.01, P = 0.90). Multivariate regression analysis revealed that NSMIA was significantly associated with the NIHSS score after adjusting for stroke risk factors. The adjusted odds ratio (per lateral) was 2.092 (95% CI, 0.865 to 3.308, P = 0.001). The degree of stenosis was also significantly associated with the NIHSS score after adjusting for common risk factors. The odds ratio (per 10%) was 0.712 (95% CI, 0.202 to 1.223, P = 0.007).

Conclusions

The number of stenotic intracranial major arteries is associated with the severity of ischemic stroke independent of the degree of stenosis and other stroke risk factors. To the best of our knowledge, this has not been previosuly studied in great detail using DSA. Our data highlight the importance of examining all major arteries in stroke patients.

Reflux of Anterior Spinal Artery Predicts Recurrent Posterior Circulation Stroke in Bilateral Vertebral Artery Disease

BACKGROUNDS AND PURPOSE

Predictive value of reflux of anterior spinal artery for recurrent posterior circulation ischemia in bilateral vertebral arteries steno-occlusive disease was evaluated.

METHODS

We retrospectively reviewed 55 patients with symptomatic posterior circulation stroke caused by bilateral stenotic (>70%) lesions of the vertebral artery. We investigated any correlation of clinical and angiographic characteristics including collateral flow patterns, with recurrent stroke. Risk factors for poor 3-month functional outcome were also evaluated.

RESULTS

Recurrent posterior circulation stroke was observed in 15 (27.3%) patients. Multivariable analysis using Cox proportional hazards model showed anterior spinal artery reflux as a significant risk factor for stroke recurrence (adjusted hazard ratio, 19.3 [95% confidence interval, 5.35-69.9]; P<0.001). Anterior spinal artery reflux was also correlated with poor functional outcome (modified Rankin Scale score, 3-6; adjusted odds ratio, 7.41 [95% confidence interval, 1.24-44.4]; P=0.028).

CONCLUSIONS

In patients with symptomatic bilateral vertebral artery occlusive disease, anterior spinal artery reflux predicted recurrent posterior circulation stroke and poor functional outcome.

Contemporary Cardiovascular Concerns after Spinal Cord Injury: Mechanisms, Maladaptations, and Management

Cardiovascular (CV) issues after spinal cord injury (SCI) are of paramount importance considering they are the leading cause of death in this population. Disruption of autonomic pathways leads to a highly unstable CV system, with impaired blood pressure (BP) and heart rate regulation. In addition to low resting BP, on a daily basis the majority of those with SCI suffer from transient episodes of aberrantly low and high BP (termed orthostatic hypotension and autonomic dysreflexia, respectively). In fact, autonomic issues, including resolution of autonomic dysreflexia, are frequently ranked by individuals with high-level SCI to be of greater priority than walking again. Owing to a combination of these autonomic disturbances and a myriad of lifestyle factors, the pernicious process of CV disease is accelerated post-SCI. Unfortunately, these secondary consequences of SCI are only beginning to receive appropriate clinical attention. Immediately after high-level SCI, major CV abnormalities present in the form of neurogenic shock. After subsiding, new issues related to BP instability arise, including orthostatic hypotension and autonomic dysreflexia. This review describes autonomic control over the CV system before injury and the mechanisms underlying CV abnormalities post-SCI, while also detailing the end-organ consequences, including those of the heart, as well as the systemic and cerebral vasculature. The tertiary impact of CV dysfunction will also be discussed, such as the potential impediment of rehabilitation, and impaired cognitive function. In the recent past, our understanding of autonomic dysfunctions post-SCI has been greatly enhanced; however, it is vital to further develop our understanding of the long-term consequences of these conditions, which will equip us to better manage CV disease morbidity and mortality in this population.

Bilateral Intracranial Vertebral Artery Stenosis Presenting as Recurrent Prolonged Presyncopal Episodes

Amongst various mechanisms of presyncopal events, posterior circulation disease needs to be considered. This particular mechanism has been underrecognized. We describe a case of a 76-year-old patient with recurrent posterior circulation TIAs, presenting as recurrent prolonged presyncopal events.

Intradural vertebral endarterectomy with nonautologous patch angioplasty for refractory vertebrobasilar ischemia: Case report and literature review

BACKGROUND

The natural history of patients with symptomatic vertebrobasilar ischemic symptoms due to chronic bilateral vertebral artery occlusive disease is progressive, and poses significant challenges when refractory to medical therapy. Surgical treatment options depend largely on location and characteristics of the atheroma (s), and generally include percutaneous transluminal angioplasty (PTA) with or without stent placement, posterior circulation revascularization (bypass), extracranial vertebral artery reconstruction, or vertebral artery endarterectomy.

CASE DESCRIPTION

We present the case of a 56-year-old male with progressive vertebrobasilar ischemia due to tandem lesions in the right vertebral artery at the origin and intracranially in the V4 segment. The contralateral vertebral artery was occluded to the level of posterior inferior cerebellar artery (PICA) and posterior communicating arteries were absent. Following PTA and stent placement at the right vertebral artery origin, the patient was successfully treated with intradural vertebral artery endarterectomy (V4EA) and patch angioplasty via the far lateral approach. Distal endovascular intervention at the V4 segment proved not technically feasible after multiple attempts.

CONCLUSIONS

V4EA is an uncommonly performed procedure, but may be considered for carefully selected patients. The authors' techniques and indications are discussed. Historical outcomes, relevant anatomic considerations, and lessons learned are reviewed from the literature.

Endovascular recanalization for chronic symptomatic intracranial vertebral artery total occlusion

Purpose. The outcome of recanalization in patients with chronic symptomatic intracranial vertebral artery (ICVA) total occlusion is poor. This paper reports the technical feasibility and long-term outcome of ICVA stenting in patients with chronic symptomatic total occlusion. Methods. Retrospective review of our prospectively maintained intracranial intervention database to identify patients with symptomatic total occlusion of ICVA with revascularization attempted >1 month after index ischemic event. Results. Eight patients (mean age 58 years) were identified. One had stroke and 7 had recurrent transient ischemic attacks. Four had bilateral ICVA total occlusion and 4 had unilateral ICVA total occlusion with severe stenosis contralaterally. Seven of 8 patients underwent endovascular recanalization, which was achieved in 6. Periprocedural complications included cerebellum hemorrhage, arterial dissection, perforation, and subacute in-stent thrombosis which occurred in 3 patients. One patient died of cerebellum hemorrhage. The other patients improved clinically after endovascular therapy. Conclusions. Stent-supported recanalization of ICVA total occlusion is technically feasible, and may become a viable treatment option in selected patients.

Natural history of intracranial atherosclerotic disease

Intracranial atherosclerotic disease was very common among stroke patients of Asians, Blacks, and Hispanics ancestry. Furthermore, stroke patients with intracranial atherosclerosis (ICAS) have higher recurrence rate of cerebral ischemia and death than those without ICAS. However, the natural history of intracranial atherosclerotic disease is still in controversy. Most of the studies were retrospective and randomized controlled trial of drugs. This review summarized the prognosis of symptomatic and asymptomatic intracranial atherosclerotic disease in order to guide clinical decision-making and further clinical research.

Regional neurovascular coupling and cognitive performance in those with low blood pressure secondary to high-level spinal cord injury: improved by alpha-1 agonist midodrine hydrochloride

Individuals with high-level spinal cord injury (SCI) experience low blood pressure (BP) and cognitive impairments. Such dysfunction may be mediated in part by impaired neurovascular coupling (NVC) (i.e., cerebral blood flow responses to neurologic demand). Ten individuals with SCI >T6 spinal segment, and 10 age- and sex-matched controls were assessed for beat-by-beat BP, as well as middle and posterior cerebral artery blood flow velocity (MCAv, PCAv) in response to a NVC test. Tests were repeated in SCI after 10 mg midodrine (alpha1-agonist). Verbal fluency was measured before and after midodrine in SCI, and in the control group as an index of cognitive function. At rest, mean BP was lower in SCI (70 ± 10 versus 92 ± 14 mm Hg; P<0.05); however, PCAv conductance was higher (0.56 ± 0.13 versus 0.39 ± 0.15 cm/second/mm Hg; P<0.05). Controls exhibited a 20% increase in PCAv during cognition; however, the response in SCI was completely absent (P<0.01). When BP was increased with midodrine, NVC was improved 70% in SCI, which was reflected by a 13% improved cognitive function (P<0.05). Improvements in BP were related to improved cognitive function in those with SCI (r(2)=0.52; P<0.05). Impaired NVC, secondary to low BP, may partially mediate reduced cognitive function in individuals with high-level SCI.

Perturbed and spontaneous regional cerebral blood flow responses to changes in blood pressure after high-level spinal cord injury: the effect of midodrine

Individuals with spinal cord injury (SCI) above the T6 spinal segment suffer from orthostatic intolerance. How cerebral blood flow (CBF) responds to orthostatic challenges in SCI is poorly understood. Furthermore, it is unclear how interventions meant to improve orthostatic tolerance in SCI influence CBF. This study aimed to examine 1) the acute regional CBF responses to rapid changes in blood pressure (BP) during orthostatic stress in individuals with SCI and able-bodied (AB) individuals; and 2) the effect of midodrine (alpha1-agonist) on orthostatic tolerance and CBF regulation in SCI. Ten individuals with SCI >T6, and 10 age- and sex-matched AB controls had beat-by-beat BP and middle and posterior cerebral artery blood velocity (MCAv, PCAv, respectively) recorded during a progressive tilt-test to quantify the acute CBF response and orthostatic tolerance. Dynamic MCAv and PCAv to BP relationships were evaluated continuously in the time domain and frequency domain (via transfer function analysis). The SCI group was tested again after administration of 10 mg midodrine to elevate BP. Coherence (i.e., linearity) was elevated in SCI between BP-MCAv and BP-PCAv by 35% and 22%, respectively, compared with AB, whereas SCI BP-PCAv gain (i.e., magnitudinal relationship) was reduced 30% compared with AB (all P < 0.05). The acute (i.e., 0-30 s after tilt) MCAv and PCAv responses were similar between groups. In individuals with SCI, midodrine led to improved PCAv responses 30-60 s following tilt (10 ± 3% vs. 4 ± 2% decline; P < 0.05), and a 59% improvement in orthostatic tolerance (P < 0.01). The vertebrobasilar region may be particularly susceptible to hypoperfusion in SCI, leading to increased orthostatic intolerance.

Brain involvement in Alström syndrome

BACKGROUND

Alström Syndrome (AS) is a rare ciliopathy characterized by cone-rod retinal dystrophy, sensorineural hearing loss, obesity, type 2 diabetes mellitus and cardiomyopathy. Most patients do not present with neurological issues and demonstrate normal intelligence, although delayed psychomotor development and psychiatric disorders have been reported. To date, brain Magnetic Resonance Imaging (MRI) abnormalities in AS have not been explored.

METHODS

We investigated structural brain changes in 12 genetically proven AS patients (mean-age 22 years; range: 6-45, 6 females) and 19 matched healthy and positive controls (mean-age 23 years; range: 6-43; 12 females) using conventional MRI, Voxel-Based Morphometry (VBM) and Diffusion Tensor Imaging (DTI).

RESULTS

6/12 AS patients presented with brain abnormalities such as ventricular enlargement (4/12), periventricular white matter abnormalities (3/12) and lacune-like lesions (1/12); all patients older than 30 years had vascular-like lesions. VBM detected grey and white matter volume reduction in AS patients, especially in the posterior regions. DTI revealed significant fractional anisotropy decrease and radial diffusivity increase in the supratentorial white matter, also diffusely involving those regions that appeared normal on conventional imaging. On the contrary, axial and mean diffusivity did not differ from controls except in the fornix.

CONCLUSIONS

Brain involvement in Alström syndrome is not uncommon. Early vascular-like lesions, gray and white matter atrophy, mostly involving the posterior regions, and diffuse supratentorial white matter derangement suggest a role of cilia in endothelial cell and oligodendrocyte function.

Cerebral autoregulation in the vertebral and middle cerebral arteries during combine head upright tilt and lower body negative pressure in healthy humans

The majority of cerebral autoregulation research has focused on the middle cerebral artery. However, many symptoms of presyncope indicate posterior cerebral hypoperfusion. To address this issue, we measured cerebrovascular reactivity, cerebral blood flow velocity and dynamic cerebral autoregulation in the middle cerebral artery and vertebral arteries during orthostatic stress to presyncope in 9 healthy subjects. There was no significant difference in either the decline in cerebral blood flow velocity or indices of dynamic cerebral autoregulation between the middle cerebral and vertebral arteries prior to or during presyncope. In conclusion, there is no significant difference in regulation of blood flow between the vertebral artery and middle cerebral artery in healthy subjects. Further study is required to determine whether or not a difference exists in syncopal patient populations.

Diagnosis of intracranial atherosclerosis

IMPORTANCE OF THE FIELD

Intracranial atherosclerosis is quickly becoming the most common stroke mechanism worldwide. Accurate diagnosis is important in making treatment decisions.

AREAS COVERED IN THE REVIEW

In this article the clinical and radiographic diagnosis of intracranial atherosclerosis is reviewed. An overview is provided of widely available invasive and non-invasive methods for the detection of intracranial atherosclerosis, including transcranial Doppler, magnetic resonance and computed tomography angiography, as well as conventional angiography.

WHAT THE READER WILL GAIN

The reader will become familiar with the advantages and limitations of various imaging modalities used in the diagnosis of intracranial atherosclerosis.

TAKE HOME MESSAGE

Non-invasive imaging modalities have a high negative predictive value in detecting intracranial atherosclerosis. The gold standard for confirmation of the diagnosis remains catheter angiography.

Rotational vertebrobasilar ischemia due to vertebral artery dynamic stenoses complicated by an ostial atherosclerotic stenosis

Abstract

We describe a patient with rotational vertebrobasilar ischemia (RVBI) due to vertebral artery (VA) compressive stenoses during neck rotation, complicated by an ostial atherosclerotic stenosis (OAS). Referred for ‘near-syncopal spells’, inquiry revealed a symptom-complex consistent with vertebrobasilar transient ischemic attacks (TIAs) provoked by head rotation. VA dynamic angiography with imaging via prevertebral subclavian injections in neck-rotated positions while reproducing symptoms, demonstrated two compressive stenoses not present in the neck-neutral position, establishing the diagnosis of RVBI due to CT-demonstrated cervical spondylosis. There was an occluded contralateral VA, isolated posterior circulation, and absent vertebral collateral flow. Disabling symptoms persisted despite using a cervical collar. Surgical decompression of the dynamic stenoses would not address the OAS, was considered high risk, and absence of a suitable donor artery precluded distal VA reconstruction. RVBI resolved with ostial stent placement by improving perfusion pressure across the compressive stenoses. To our knowledge, this is the first report of RVBI in which the affected VA had an obstructive atherosclerotic stenosis in addition to the characteristic rotation-induced dynamic stenoses, and the first report of stent placement in the culprit artery to treat this disorder. Diagnosis depends on recognizing the association of symptoms with positional neck changes and VA dynamic angiography demonstrating the compressive stenosis while reproducing symptoms. This case illustrates the management complexities when there are coexisting abnormalities, emphasizing the need to individualize treatment. RVBI is a potentially correctable cause of TIAs and particularly relevant due to the aging population which has a significant incidence of both degenerative cervical and atherosclerotic cerebrovascular disease.

Brainstem ischemia, steno-occlusive pathology of the vertebral arteries, and alterations in the circadian blood pressure pattern: a case report

We report the case of a patient with vertebrobasilar steno-occlusive pathology associated with ischemic brainstem symptomatic lesions related to abnormal decrease in blood pressure (BP). A 63-year-old man presented vertigo and persistent gait impairment as a result of a posterior cerebellar infarction and, during hospitalization, experienced a new episode of cerebral ischemia in the territory of the anterior cerebellar artery. Cerebral angiography showed occlusion of the left vertebral artery and two severe stenoses of the right vertebral artery, and 24-hour dynamic BP monitoring evidenced severe postprandial hypotension. Medical treatment was not effective so he underwent an endovascular procedure. This report documents the importance of BP monitoring for a better understanding of the pathophysiology of posterior ischemic strokes and, above all, for a more reliable prognosis and therapy.

Bilateral vertebral artery occlusion with retrograde basilary flow in three cases of giant cell arteritis

Vertebrobasilar ischaemia is a rare life-threatening complication in giant cell arteritis (GCA). We report three patients with bilateral vertebral artery occlusion. Neurovascular imaging, including CT-angiography, MR-angiography and colour-coded duplex sonography revealed flow reversal in the basilar artery as well as inflammation of the vertebral vessel wall. The first patient died from massive brainstem infarction, the other two patients survived the initial inflammatory phase of GCA. No stroke recurrence at 12 months' follow-up on warfarin and steroid treatment was observed. Bilateral distal vertebral artery occlusion and retrograde basilar artery flow persisted.Outcome in these patients is dependant on potent immunosuppression, concurrent atherosclerotic steno-occlusive disease and presence and/or rapid development of sufficient collateral pathways into the vertebrobasilar circulation. The identification of patients with high risk of ischaemia due to compromised vertebrobasilar flow may be important to select adjunct treatment to immunosuppression, such as anticoagulation in GCA.

Prognostic value of CT angiography in patients with suspected vertebrobasilar ischemia

BACKGROUND

The outcome of vertebrobasilar ischemia depends on the clinical presentation and the presence or absence of vascular occlusion. The aim of our study was to analyze the CT angiography (CTA) predictors of outcome in patients with suspected vertebrobasilar ischemia.

METHODS

We studied patients with suspected acute vertebrobasilar ischemia between April 2002 and January 2006 and had CTA done within 24 hours of symptom onset. We reviewed the final diagnosis and 3-month follow-up and analyzed the clinical and CTA predictors of outcome.

RESULTS

Of the 133 patients, 21(15%), 18 (13%), and 16 (12%) had occlusion of basilar artery (BA), vertebral artery (VA), and posterior cerebral artery (PCA) respectively. The final diagnosis was stroke in 98 (73.6%), transient ischemic attack (TIA) in 10 (7.5%), and nonischemic in 25 (18.8%). No vascular occlusion was seen on CTA in patients with TIA and nonischemic diagnosis. At 3-month follow-up, we found a mortality rate of 10.6% and good functional outcome in 71.4%. The predictors of death in the multivariable analysis were the presence of BA occlusion (odds ratio[OR] 6.7, 95% CI, 1.4-30.6) and baseline National Institutes of Health Stroke Scale (NIHSS) (OR 1.14, 95% CI, 1.06-1.2). When patients with basilar occlusion were excluded, the presence of VA occlusion (OR 6.5, 95% CI, 1.34-31.4), age (OR 1.09, 95% CI, 1.03-1.14), and baseline NIHSS (OR 1.1, 95% CI, 1.03-1.18) predicted poorer outcome.

CONCLUSIONS

The presence or absence of a vascular occlusion is a critical factor for prognosis in suspected acute vertebrobasilar ischemia and is correlated with the location of occlusion.

Bilateral vertebral artery disease: transcranial Doppler assessment of the hemodynamic vulnerability to changes in posture

Posture changes may cause hemodynamic ischemic events, particularly in severe vertebrobasilar artery disease. It may be difficult and not without risk to prove this vulnerability to changes in posture during angiography. Therefore, TCD monitoring with passive tilting (PT) was used to evaluate cerebral hemodynamics distally to severe bilateral vertebral artery disease (BVAD). PCA flow velocity changes and dynamic cerebral autoregulation (DCA) were analyzed in supine and upright position. Despite a significant autoregulatory deficit distally to BVAD, the posterior cerebral blood supply seemed to be sufficiently maintained as long as systemic blood pressure changes were within normal limits. Posterior cerebral flow velocities, however, were significantly diminished when PT detected a systemic hypotension in upright position. This study proves the feasibility to combine PT and TCD monitoring of the PCA in patients with BVAD. In vertebrobasilar artery disease, the examination of spontaneous and tilt-induced autoregulatory responses could support the evaluation of a risk for hemodynamic ischemia.

Atherosclerosis in the vertebral artery: an intrinsic risk factor in the use of spinal manipulation?

The presence of atherosclerotic plaques and their influence on the vertebral artery is of clinical importance within the scope of spinal manipulation. Manipulation may stimulate the development of atherosclerotic plaques, could detach an embolus with ensuing infarction, injure the endothelium or may directly cause a dissection in the presence of atherosclerotic plaques. In order to identify the sites and frequency of atherosclerotic plaques and to determine its relation to the tortuous course of the vertebral artery, a cadaveric study was performed. The vertebral arteries of 57 human cadavers were studied. The vertebral artery was virtually divided into four segments: the pre-vertebral (V1), the vertebral (V2), the atlanto-axial (V3), and the intracranial segment (V4). Abnormalities in the origin and course of the vertebral artery were noted, along with any associated osseous, or cartilaginous anomalies in the neck. After dissection, the artery was opened and macroscopically screened for the presence of atherosclerotic plaques. In 22.8% of the cases, no atherosclerotic plaques were present. In 35.1% of the cases, the atherosclerotic plaques were unilateral, of which 60.0% was on the left side, 40.0% on the right side, and in 42.1%, the occurrence was bilateral. Atherosclerotic plaques were significantly more present in the V3 segment than in the V1 (0.007) and V2 segment (0.049). In the V1 (P=0.008) and V2 segment (P=0.002), there was a correlation between a tortuous course of the vessel and the occurrence of atherosclerotic plaques. In individuals with marked atherosclerotic disease, stretching and compression effects of rotational manipulative techniques on atherosclerotic vessels impose a further risk factor for vertebrobasilar insufficiency. As direct evidence of atherosclerotic plaques are rarely available, therapists should avoid manipulative techniques at all levels of the cervical spine in the presence of any indirect sign of atherosclerotic disease or in the presence of calcified arterial walls or tortuosities of the vessels visible on routinely available X-ray images of the cervical or thoracic spine. It is strongly recommended, that if any doubt exists about the nature of a clinical presentation, vigorous manual procedures should be avoided until either the diagnosis is definitive or gentle manual therapy has proven effective.

The vertebral artery: a review of anatomical, histopathological and functional factors influencing blood flow to the hindbrain

An uncompromised blood flow to the brain is essential for normal neurological function. If the blood supply to the hindbrain, via the paired vertebral arteries, is reduced sufficiently, signs and symptoms of tertebrobasilar ischaemia may result. There are several factors that may cause a reduction in vertebral artery blood flow. These include exostoses, such as the retroarticular canal and lateral bridge of the atlas vertebra that may cause compression of the related part of the vertebral artery; or atherosclerosis of the artery wall occluding the vessel lumen. Functional factors, such as sustained end-of-range rotation of the cervical spine, may cause distortion of the vertebral artery in the suboccipital region, which may be reflected as decreased blood flow in the suboccipital and intracranial parts of the artery. A combination of such factors is likely to cause reduced blood flow to the hindbrain. It is the purpose of this review to highlight some of the factors that may compromise vertebral artery blood flow and, therefore, to provide some evidence on which to base our professional practice.

Impact of vertebral artery disease on dynamic cerebral autoregulation

OBJECTIVES

This study applied dynamic cerebral autoregulation (DCA) testing distally to severe bilateral vertebral artery disease (BVAD).

METHODS

Using continuous monitoring of beat-to-beat blood pressure and transcranial Doppler of the posterior cerebral arteries (PCA) were examined in 20 patients with BVAD and 22 controls. DCA testing was based on the 'high-pass filter model', which predicts a positive phase relationship between spontaneous oscillations (M-waves 3-9 cpm and R-waves 9-20 cpm) in blood pressure and cerebral blood flow velocity.

RESULTS

In patients with BVAD, DCA testing detected autoregulatory deficits of different degrees. The lowest M-wave phase shift angles were found in the PCA territory distally to intracranial BVAD.

CONCLUSION

This study suggests that DCA testing of the PCA could help to quantify the hemodynamic impact of BVAD. It highlights the relevance of functional TCD sonography as a useful diagnostic tool for the hemodynamic evaluation of vertebrobasilar disease.

Spectrum of the Posterior Inferior Cerebellar Artery Territory Infarcts

BACKGROUND AND PURPOSE

The clinical, etiological and stroke mechanisms are defined well before but the detailed clinical and etiologic mechanisms regarding to all clinical spectrum of posterior inferior cerebellar artery (PICA) infarcts were not systematically studied by diffusion-weighted imaging (DWI).

METHODS

Seventy-four patients with PICA territory ischemic lesion proved by DWI with decreased apparent diffusion coefficient and FLAIR (fluid attenuation inversion recovery) included in our Registry, corresponding to 2% of 3,650 patients with ischemic stroke, were studied. The presence of steno-occlusive lesions in the posterior circulation were sought by magnetic resonance angiography, and reviewed with a three-dimensional rotating cineangiographic method.

RESULTS

We found six subgroups of PICA territory infarcts according clinico-topographical relationship: (1) 9 patients with lesion in the territory lateral branch of PICA; (2) 23 patients with an infarct in the territory of medial branch of PICA; (3) 9 patients with a lesion involving both medial and lateral branches of the PICA; (4) 9 patients with cortical infarcts at the boundary zones either between medial and lateral branches of the PICA or between PICA and m/l superior cerebellar artery (SCA); (5) 10 patients with a lesion at the deep boundary zones either between medial and lateral PICA, or between PICA and medial/lateral SCA; (6)14 patients with concomitant multiple lesions in the PICA and in other vertebrobasilar artery territories. The main cause of PICA infarcts was extracranial large-artery disease in 30 patients (41%) patients, cardioembolism and in situ branch disease in 15 patients (20%) each.

CONCLUSIONS

Multiple PICA territory lesions on DWI were not uncommon and could be caused by multiple emboli originating from break-up of atherosclerotic plaque in the subclavian/innominate-vertebral arterial system. DWI findings of single or multiple small lesions could account for some cases with transient and subtle cerebellar symptoms which have been considered before as 'vertebrobasilar insufficiency' without morphologic lesion. Different clinical-DWI correlations allow us to determine better definition of the topographical and etiological spectrum of acute PICA territory lesions, which was previously defined by pathological and conventional MRI studies.

Transcranial color-coded sonography for vertebrobasilar disorders in end-stage renal disease

Because vertebrobasilar arterial disorders seem to be common in patients with end-stage renal disease, a neuroradiological evaluation of vertebrobasilar circulation is necessary for patients with possible vertebrobasilar insufficiency. In three patients on maintenance hemodialysis, contrast-enhanced transcranial color-coded real-time sonography (TCCS) through a suboccipital window delineated occlusion of bilateral vertebral arteries with reversal of the basilar artery, reversal of the left vertebral artery mimicking left subclavian steal phenomenon, and dolichoectasia of the basilar artery and bilateral vertebral arteries with signals of turbulent flow. TCCS has several advantages over computed tomographic angiography and magnetic resonance angiography, including the direction of blood flow, handy performance even during hemodialysis, and contrast agent free from nephrotoxicity. Thus, TCCS is useful in the evaluation of intracranial circulation in patients with end-stage renal disease.

New England Medical Center Posterior Circulation Stroke Registry II. Vascular Lesions

Among 407 New England Medical Center Posterior Circulation Registry (NEMC-PCR) patients, the extracranial (ECVA) and intracranial vertebral arteries (ICVA) were the commonest sites of severe occlusive disease followed by the basilar artery (BA). Severe occlusive lesions were found in >1 large artery in 148 patients; 134 had unilateral or bilateral severe disease at one arterial location. Single arterial site occlusive disease occurred most often in the ECVA (52 patients, 15 bilateral) followed by the ICVA (40 patients, 12 bilateral) and the BA (46 patients). Involvement of the ICVAs and the BA was very common and some patients also had ECVA lesions. Hypertension, smoking, and coronary and peripheral vascular disease were most prevalent in patients with extracranial disease while diabetes and hyperlipidemia were more common when occlusive lesions were only intracranial. Intra-arterial embolism was the most common mechanism of brain infarction in patients with ECVA and ICVA occlusive disease. ICVA occlusive lesions infrequently caused infarction limited to the proximal territory (medulla and posterior inferior cerebellum). BA lesions most often caused infarcts limited to the middle posterior circulation territory (pons and anterior inferior cerebellum). Posterior cerebral artery occlusive lesions were predominantly embolic. Penetrating artery disease caused mostly pontine and thalamic infarcts. Prognosis was poorest in patients with BA disease. The best prognosis surprisingly was in patients who had multiple arterial occlusive lesions; they often had position-sensitive transient ischemic attacks during months or years.

New England medical center posterior circulation stroke registry: I. Methods, data base, distribution of brain lesions, stroke mechanisms, and outcomes

Among 407 New England Medical Center Posterior Circulation Registry (NEMC-PCR) patients, 59% had strokes without transient ischemic attacks (TIAs), 24% had TIAs before strokes, and 16% had only posterior circulation TIAs. Embolism was the commonest stroke mechanism accounting for 40% of cases (24% cardiac origin, 14% arterial origin, 2% had potential cardiac and arterial sources). In 32%, large artery occlusive lesions caused hemodynamic brain infarction. Stroke mechanisms in the posterior and anterior circulation are very similar. Infarcts most often included the distal posterior circulation territory (rostral brainstem, superior cerebellum and occipital and temporal lobes), while the proximal (medulla and posterior inferior cerebellum) and middle (pons and anterior inferior cerebellum) territories were equally involved. Infarcts that included the distal territory were twice as common as those that included the proximal or middle territories. Most distal territory infarcts were attributable to embolism. Thirty day mortality was low (3.6%). Embolic stroke mechanism, distal territory location, and basilar artery occlusive disease conveyed the worst prognosis.

Risk factors for occlusive lesions of intracranial arteries in stroke-free Japanese

The aim of this study was to identify relevant risk factors for occlusive lesions of the intracranial arteries in stroke-free population. The subjects of this study were 425 patients without a history of stroke or transient ischemic attack and without any abnormality on a neurological examination who consecutively visited a neurology clinic between January 1994 and June 2001 requesting medical evaluation for possible cerebrovascular diseases. Subjects included 245 men and 180 women ranging in age from 33 to 89 years (mean+/-SD=64.0+/-10.0 years). We performed cervical and intracranial magnetic resonance angiography (MRA) in all subjects. Using a validated rating scheme of MRA for occlusive lesions, we evaluated the degree of stenoses in the extracranial portion of the internal carotid artery (ICA) and the intracranial arteries including the intracranial portion of the ICA, middle cerebral artery (MCA) stem, intracranial portion of the vertebral artery (VA), and basilar artery (BA). More than 25% stenoses were regarded as significant lesions in this study. Multiple logistic regression analyses showed that significant and independent predictors for extracranial ICA lesions were age, hyperlipidemia, and ischemic heart disease (IHD), those for intracranial ICA lesions were age, hypertension, diabetes mellitus, and IHD, those for MCA lesions were age and hypertension, those for intracranial VA lesions were hyperlipidemia and IHD, and those for BA lesions were hypertension and diabetes mellitus. The present study suggested that atherosclerosis of the intracranial VA was related to hyperlipidemia and IHD as was the case for the extracranial carotid artery, whilst atherosclerosis of other sites of intracranial arteries was associated with hypertension and diabetes mellitus in stroke-free Japanese.

Complete Nonvisualization of Basilar Artery on MR Angiography in Patients with Vertebrobasilar Ischemic Stroke: Favorable Outcome Factors

BACKGROUND

In vertebrobasilar ischemic stroke, magnetic resonance angiography (MRA) occasionally fails to visualize the basilar artery, but in these patients, little attention has been given to establishing correlations between the clinical and the radiological findings. Our aim was to identify clinical or radiological measures that could assist in predicting a favorable clinical outcome.

METHODS

Risk factors, clinicoradiological features, and functional outcomes were assessed in 40 patients with vertebrobasilar ischemic stroke whose basilar arteries were absent on MRA. The presence of potential feeding arteries to the posterior circulation was recorded from a review of the MRA data. To permit quantitative analysis of the images, a potential feeding artery score (PFAS; range: 0-8) was established. One point was assigned when a signal was seen from an intracranial vertebral artery, a posterior inferior cerebellar artery, a superior cerebellar artery, or a posterior cerebral artery. On MRI, the location of the infarction was classified as involving the proximal, middle, and distal territories of the intracranial posterior circulation. The infarctions were also categorized as single- or multi-sector infarctions, and according to whether more than one penetrating or branch artery was involved. Clinical outcomes were classified as favorable (modified Rankin Scale = 0-2) or poor (modified Rankin Scale = 3-6).

RESULTS

The clinical outcome was favorable in 30% (n = 12) of patients, and poor in 70% (n = 28). A transient ischemic attack preceded the stroke in 48% of patients, especially those with a favorable outcome (67%). Patients with a favorable outcome had a higher PFAS (p = 0.036) and an increased incidence of single-sector infarction (p = 0.049).

CONCLUSIONS

Our study suggests that a higher PFAS, accompanied by a single-sector infarction, is a predictor of improved clinical outcome in patients with vertebrobasilar ischemic stroke in which the basilar artery was absent on MRA.