Adam de Havenon

Multicontrast High-Resolution Vessel Wall Magnetic Resonance Imaging and Its Value in Differentiating Intracranial Vasculopathic Processes

Background and Purpose— Although studies have attempted to differentiate intracranial vascular disease using vessel wall magnetic resonance imaging (VWI), none have incorporated multicontrast imaging. This study uses T1- and T2-weighted VWI to differentiate intracranial vasculopathies. Methods— We retrospectively reviewed patients with clinically defined intracranial vasculopathies causing luminal stenosis/irregularity who underwent VWI studies. Two blinded experts evaluated T1 precontrast and postcontrast and T2-weighted VWI characteristics, including the pattern of wall thickening; presence, pattern, and intensity of postcontrast enhancement; and T2 signal characteristics. Results— Twenty-one cases of atherosclerosis (intracranial atherosclerotic disease [ICAD]), 4 of reversible cerebral vasoconstriction syndrome, and 4 of vasculitis were identified, with a total of 118 stenotic lesions (81 ICAD, 22 reversible cerebral vasoconstriction syndrome, and 15 vasculitic lesions). There was substantial to excellent inter-reader agreement for the assessment of lesional T2 hyperintensity (&kgr;=0.80), pattern of wall thickening (&kgr;=0.87), presence (&kgr;=0.90), pattern (&kgr;=0.73), and intensity (&kgr;=0.77) of enhancement. ICAD lesions were significantly more likely to have eccentric wall involvement (90.1%) than reversible cerebral vasoconstriction syndrome (8.2%; P<0.001) and vasculitic lesions (6.7%; P<0.001) and were also more likely to have T2 hyperintensity present than the other 2 vasculopathies (79% versus 0%; P<0.001). There were also significant differences in the presence, intensity, and pattern of enhancement between all lesion types. Combining T1 and T2 VWI increased the sensitivity of VWI in differentiating ICAD from other vasculopathies from 90.1% to 96.3%. Conclusions— Multicontrast VWI can be a complementary tool for intracranial vasculopathy differentiation, which often leads to more invasive workups when reversible cerebral vasoconstriction syndrome and vasculitis are in the differential diagnosis.

Posterior reversible encephalopathy syndrome with spinal cord involvement

Objective: To characterize a cohort of patients with the signs and symptoms of posterior reversible encephalopathy syndrome (PRES), but with clinical and radiologic involvement of the spinal cord. Methods: We report 2 cases of PRES with spinal cord involvement and identified an additional 6 cases in the Medline database using various search terms related to “spinal PRES,” “spinal reversible posterior leukoencephalopathy syndrome,” and “spinal hypertensive encephalopathy.” We analyzed the clinical and imaging characteristics of the 8 cases. Results: Average age was 31 years, with 5 male and 3 female patients. All patients had severe acute hypertension and a confluent, expansile central spinal cord T2 hyperintensity spanning at least 4 spinal segments, originating at the cervicomedullary junction. Of 8 patients, 7 had hypertensive retinopathy, a favorable clinical course with only antihypertensive treatment, and resolution of the spinal cord lesions on follow-up imaging. A total of 4 of 8 patients had symptoms referable to the spinal cord lesions and only 1 of 8 had a seizure. Conclusion: In light of the already wide definition of PRES, we propose a new syndrome named PRES with spinal cord involvement (PRES-SCI). Clinicians should suspect PRES-SCI when patients with PRES have neurologic signs referable to the spinal cord, extreme elevation in blood pressure, MRI lesions that extend to the cervicomedullary junction, or grade IV hypertensive retinopathy. These clinical scenarios should prompt a cervical spine MRI to help guide patient management decisions and prognostication. When clinicians evaluate longitudinally extensive spinal T2 hyperintensities, they should consider PRES-SCI, which, if diagnosed, would spare patients the morbidity of a standard myelitis workup and empiric treatment.

The Secret “Spice”: An Undetectable Toxic Cause of Seizure

Neurologists and emergency department physicians are frequently involved in the comprehensive evaluation of a first generalized seizure. An important aspect of this evaluation is a detailed history which can identify a provoked seizure secondary to drug toxicity and hence avoid unnecessary treatment with antiepileptic drugs. “Spice” is an umbrella term for a variety of synthetic cannabinoid products whose inhalation has been associated with an increasing number of toxic side effects resulting in emergency department visits. These side effects (including psychosis, tachyarrhythmia, and seizures) are not typically seen with marijuana (Cannabis sativa) use. We report 2 patients with no prior history of neurological disease that experienced their first generalized tonic–clonic seizure after smoking Spice. The mechanism behind the possible proconvulsant effect of synthetic cannabinoids is not known, but it may be due to their effects at the cannabinoid receptor CB1. Although the US Drug Enforcement Administration placed 5 synthetic cannabinoids into schedule 1 for a 12-month period beginning March 2011, new Spice products containing different synthetic cannabinoids continue to emerge. Because synthetic cannabinoids are not detectable on commercial drug screens it is important that neurologists and emergency department physicians consider Spice inhalation in their differential diagnosis of a first generalized seizure.

Advanced imaging in acute ischemic stroke

The evaluation and management of acute ischemic stroke has primarily relied on the use of conventional CT and MRI techniques as well as lumen imaging sequences such as CT angiography (CTA) and MR angiography (MRA). Several newer or less-established imaging modalities, including vessel wall MRI, transcranial Doppler ultrasonography, and 4D CTA and MRA, are being developed to complement conventional CT and MRI techniques. Vessel wall MRI provides high-resolution analysis of both extracranial and intracranial vasculature to help identify previously occult lesions or characteristics of lesions that may portend a worse natural history. Transcranial Doppler ultrasonography can be used in the acute setting as a minimally invasive way of identifying large vessel occlusions or monitoring the response to stroke treatment. It can also be used to assist in the workup for cryptogenic stroke or to diagnose a patent foramen ovale. Four-dimensional CTA and MRA provide a less invasive alternative to digital subtraction angiography to determine the extent of the clot burden and the degree of collateral blood flow in large vessel occlusions. Along with technological advances, these new imaging modalities are improving the diagnosis, workup, and management of acute ischemic stroke- roles that will continue to expand in the future.

Added Value of Vessel Wall Magnetic Resonance Imaging in the Differentiation of Moyamoya Vasculopathies in a Non-Asian Cohort

Background and Purpose— Although studies have evaluated the differential imaging of moyamoya disease and atherosclerosis, none have investigated the added value of vessel wall magnetic resonance imaging (MRI). This study evaluates the added diagnostic value of vessel wall MRI in differentiating moyamoya disease, atherosclerotic-moyamoya syndrome (A-MMS), and vasculitic-MMS (V-MMS) with a multicontrast protocol. Methods— We retrospectively reviewed the carotid artery territories of patients with clinically defined vasculopathies (moyamoya disease, atherosclerosis, and vasculitis) and steno-occlusive intracranial carotid disease. Two neuroradiologists, blinded to clinical data reviewed the luminal imaging of each carotid, evaluating collateral extent and making a presumed diagnosis with diagnostic confidence. After 3 weeks, the 2 readers reviewed the luminal imaging+vessel wall MRI for the presence, pattern and intensity of postcontrast enhancement, T2 signal characteristics, pattern of involvement, and presumed diagnosis and confidence. Results— Ten A-MMS, 3 V-MMS, and 8 moyamoya disease cases with 38 affected carotid segments were included. There was significant improvement in diagnostic accuracy with luminal imaging+vessel wall MRI when compared with luminal imaging (87% versus 32%, P<0.001). The most common vessel wall MRI findings for moyamoya disease were nonenhancing, nonremodeling lesions without T2 heterogeneity; for A-MMS eccentric, remodeling, and T2 heterogeneous lesions with mild/moderate and homogeneous/heterogeneous enhancement; and for V-MMS concentric lesions with homogeneous, moderate enhancement. Inter-reader agreement was moderate to substantial for all vessel wall MRI characteristics (&kgr;=0.46–0.86) and fair for collateral grading (&kgr;=0.35). There was 11% inter-reader agreement for diagnosis on luminal imaging when compared with 82% for luminal imaging+vessel wall MRI (P<0.001). Conclusions— Vessel wall MRI can significantly improve the differentiation of moyamoya vasculopathies when combined with traditional imaging techniques.

Nonstenotic Culprit Plaque: The Utility of High-Resolution Vessel Wall MRI of Intracranial Vessels after Ischemic Stroke.

Intracranial atherosclerotic disease (ICAD) accounts for 9–15% of ischemic stroke in the United States. Although highly stenotic ICAD accounts for most of the strokes, it is assumed that nonstenotic ICAD (nICAD) can result in stroke, despite being missed on standard luminal imaging modalities. We describe a patient with nICAD who suffered recurrent thromboembolic stroke and TIA but had a negative conventional stroke workup. As a result, they were referred for high-resolution magnetic resonance imaging (HR-MRI) of the arterial vessel wall, which identified a nonstenotic plaque with multiple high-risk features, identifying it as the etiology of the patients thromboembolic events. The diagnosis resulted in a transition from anticoagulation to antiplatelet therapy, after which the patients clinical events resolved. HR-MRI is an imaging technique that has the potential to guide medical management for patients with ischemic stroke, particularly in cryptogenic stroke.

Association of Collateral Blood Vessels Detected by Arterial Spin Labeling Magnetic Resonance Imaging With Neurological Outcome After Ischemic Stroke

Importance Robust collateral blood vessels have been associated with better neurologic outcome following acute ischemic stroke (AIS). The most commonly used methods for identifying collaterals are contrast-based angiographic imaging techniques, which are not possible in all patients after AIS. Objective To assess the association between the presence of collateral vessels identified using arterial spin labeling (ASL) magnetic resonance imaging, a technique that does not require exogenous administration of contrast, and neurologic outcome in patients after AIS. Design, Setting, and Participants This retrospective cohort study examined 38 patients after AIS admitted to a tertiary academic medical center between 2012 and 2014 who underwent MRI with ASL. Main Outcomes and Measures According to a prespecified hypothesis, ASL images were graded for the presence of collaterals by 2 neuroradiologists. Modified Rankin Scale (mRS) scores at discharge and other composite data were abstracted from the medical record by a neurologist blinded to radiologic data. Results Of the 38 patients, 19 (50.0%) were male, and the mean (SD) age was 61 (20) years. In 25 of 38 patients (65.8%), collaterals were detected using ASL, which were significantly associated with both a good outcome (mRS score of 0-2 at discharge; P = .02) and a 1-point decrease in mRS score at discharge (odds ratio, 6.4; 95% CI, 1.7-23.4; P = .005). In a multivariable ordinal logistic regression model, controlling for admission National Institutes of Health Stroke Scale score, history of atrial fibrillation, premorbid mRS score, and stroke parent artery status, there was a strong association between the presence of ASL collaterals and a 1-point decrease in the mRS score at discharge (odds ratio, 5.1; 95% CI, 1.2-22.1; P = .03). Conclusions and Relevance Following AIS, the presence of ASL collaterals is strongly associated with better neurological outcome at hospital discharge. This novel association between ASL collaterals and improved neurologic outcome may help guide prognosis and management, particularly in patients who are unable to undergo contrast-based radiological studies.

Added Value of Vessel Wall Magnetic Resonance Imaging for Differentiation of Nonocclusive Intracranial Vasculopathies.

Background and Purpose— Our goal is to determine the added value of intracranial vessel wall magnetic resonance imaging (IVWI) in differentiating nonocclusive vasculopathies compared with luminal imaging alone. Methods— We retrospectively reviewed images from patients with both luminal and IVWI to identify cases with clinically defined intracranial vasculopathies: atherosclerosis (intracranial atherosclerotic disease), reversible cerebral vasoconstriction syndrome, and inflammatory vasculopathy. Two neuroradiologists blinded to clinical data reviewed the luminal imaging of defined luminal stenoses/irregularities and evaluated the pattern of involvement to make a presumed diagnosis with diagnostic confidence. Six weeks later, the 2 raters rereviewed the luminal imaging in addition to IVWI for the pattern of wall involvement, presence and pattern of postcontrast enhancement, and presumed diagnosis and confidence. Analysis was performed on per-lesion and per-patient bases. Results— Thirty intracranial atherosclerotic disease, 12 inflammatory vasculopathies, and 12 reversible cerebral vasoconstriction syndrome patients with 201 lesions (90 intracranial atherosclerotic disease, 64 reversible cerebral vasoconstriction syndrome, and 47 inflammatory vasculopathy lesions) were included. For both per-lesion and per-patient analyses, there was significant diagnostic accuracy improvement with luminal imaging+IVWI when compared with luminal imaging alone (per-lesion: 88.8% versus 36.1%; P<0.001 and per-patient: 96.3% versus 43.5%; P<0.001, respectively). There was substantial interrater diagnostic agreement for luminal imaging+IVWI (&kgr;=0.72) and only slight agreement for luminal imaging (&kgr;=0.04). Although there was a significant correlation for both luminal and IVWI pattern of wall involvement with diagnosis, there was a stronger correlation for IVWI finding of lesion eccentricity and intracranial atherosclerotic disease diagnosis than for luminal imaging (&kgr;=0.69 versus 0.18; P<0.001). Conclusions— IVWI can significantly improve the differentiation of nonocclusive intracranial vasculopathies when combined with traditional luminal imaging modalities.

Determinants of the impact of blood pressure variability on neurological outcome after acute ischaemic stroke

Introduction Increased blood pressure variability (BPV) is detrimental after acute ischaemic stroke, but the interaction between BPV and neuroimaging factors that directly influence stroke outcome has not been explored. Methods We retrospectively reviewed inpatients from 2007 to 2014 with acute anterior circulation ischaemic stroke, CT perfusion and angiography at hospital admission, and a modified Rankin Scale (mRS) 30–365 days after stroke onset. BPV indices included SD, coefficient of variation and successive variation of the systolic blood pressure between 0 and 120 hours after admission. Ordinal logistic regression models were fitted to mRS with predictor variables of BPV indices. Models were further stratified by CT perfusion volumetric measurements, proximal vessel occlusion and collateral score. Results 110 patients met the inclusion criteria. The likelihood of a 1-point rise in the mRS increased with every 10 mm Hg increase in BPV (OR for the 3 BPV indices ranged from 2.27 to 5.54), which was more pronounced in patients with larger ischaemic core volumes (OR 8.37 to 18.0) and larger hypoperfused volumes (OR 6.02 to 15.4). This association also held true for patients with larger mismatch volume, proximal vessel occlusion and good collateral vessels. Conclusions These results indicate that increased BPV is associated with worse neurological outcome after stroke, particularly in patients with a large lesion core volume, concurrent viable ischaemic penumbra, proximal vessel occlusion and good collaterals. This subset of patients, who are often not candidates for or fail acute stroke therapies such as intravenous tissue plasminogen activator or endovascular thrombectomy, may benefit from interventions aimed at reducing BPV.

Increased Blood Pressure Variability Is Associated with Worse Neurologic Outcome in Acute Anterior Circulation Ischemic Stroke

Background. Although research suggests that blood pressure variability (BPV) is detrimental in the weeks to months after acute ischemic stroke, it has not been adequately studied in the acute setting. Methods. We reviewed acute ischemic stroke patients from 2007 to 2014 with anterior circulation stroke. Mean blood pressure and three BPV indices (standard deviation, coefficient of variation, and successive variation) for the intervals 0–24, 0–72, and 0–120 hours after admission were correlated with follow-up modified Rankin Scale (mRS) in ordinal logistic regression models. The correlation between BPV and mRS was further analyzed by terciles of clinically informative stratifications. Results. Two hundred and fifteen patients met inclusion criteria. At all time intervals, increased systolic BPV was associated with higher mRS, but the relationship was not significant for diastolic BPV or mean blood pressure. This association was strongest in patients with proximal stroke parent artery vessel occlusion and lower mean blood pressure. Conclusion. Increased early systolic BPV is associated with worse neurologic outcome after ischemic stroke. This association is strongest in patients with lower mean blood pressure and proximal vessel occlusion, often despite endovascular or thrombolytic therapy. This hypothesis-generating dataset suggests potential benefit for interventions aimed at reducing BPV in this patient population.