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Optimal Timing of DWI for TIA

Hatim Attar, MD

Shono K, Satomi J, Tada Y, Kanematsu Y, Yamamoto N, Izumi Y, et al. Optimal Timing of Diffusion-Weighted Imaging to Avoid False-Negative Findings in Patients With Transient Ischemic Attack. Stroke. 2017

MRI scans are the gold standard imaging modality for diagnosing acute cerebrovascular injury. The purpose of performing them in Transient Ischemic Attack (TIA) patients is to determine presence of infarction, which lends information on prognosis and risk of recurrence. This novel Japanese study has investigated Diffusion Weighted Imaging (DWI) latency from symptom onset and false negative MRI scans in TIA patients. Shono et al have determined the optimal timing of obtaining MRI scans in TIA patients to limit false negative results.

By |August 16th, 2017|clinical|0 Comments

Author Interview: Robert G. Kowalski, MD, MS

Robert G. Kowalski

Robert G. Kowalski

A conversation with Robert G. Kowalski, MD, MS, Principal Investigator, Craig Hospital, and Assistant Clinical Professor of Neurology and PM&R, University of Colorado School of Medicine, about stroke following traumatic brain injury.

Interviewed by José G. Merino, MD, Associate Professor of Neurology, University of Maryland School of Medicine.

They will be discussing the paper, “Acute Ischemic Stroke After Moderate to Severe Traumatic Brain Injury: Incidence and Impact on Outcome,” published in the July issue of Stroke.

Dr. Merino: Thank you for agreeing to the interview. Can you first briefly describe the methods and main findings of the analysis published in Stroke?

Dr. Kowalski: The study was a research collaboration between the Centers for Disease Control and Prevention (CDC) and the Traumatic Brain Injury Model Systems (TBIMS) program. It was led by researchers at Craig Hospital in Englewood, CO. Investigators studied more than 6,400 traumatic brain injury (TBI) patients over a 7.5-year period to evaluate risk factors for onset, incidence, and predictors of outcome in ischemic stroke occurring acutely after TBI. We found that 2.5% of individuals who experience a moderate to severe TBI also suffer an acute ischemic stroke (AIS) at the time of the injury. In half of these cases, the individuals experiencing stroke concurrent with brain trauma were age 40 or younger. Additionally, the study found the risk of acute ischemic stroke immediately following traumatic brain injury was 10 times the risk of ischemic stroke in the general population.

The Complex Relationship Between Statins and Intracerebral Hemorrhage Outcomes

Mark R. Etherton, MD, PhD

Siddiqui FM, Langefeld CD, Moomaw CJ, Comeau MJ, Sekar P, Rosand J, et al. Use of Statins and Outcomes in Intracerebral Hemorrhage Patients. Stroke. 2017

In this entry, I discuss a recent publication by Fazeel Siddiqui and colleagues regarding the use of statins and outcomes after intracerebral hemorrhage (ICH).

The current evidence suggests a complex relationship between serum cholesterol levels, statin use, and outcomes after ICH. Low serum cholesterol levels have been associated with increased incidence of ICH, as well as hematoma expansion. However, a prior meta-analysis demonstrated antecedent statin use was associated with decreased risk of mortality and increased likelihood of a good outcome after ICH (Jung et al. Int J Stroke. 2015). The authors, therefore, set out to investigate the relationship of statin use with ICH outcomes by evaluating 3-month disability, mortality, and hematoma size/expansion.

Author Interview: Philippa Lavallée, MD

A conversation with Philippa Lavallée, MD, Department of Neurology and Stroke Centre, Bichat University Hospital, about the importance of atypical symptoms in patients with TIA.

Interviewed by José G. Merino, MD, FAHA, Associate Professor of Neurology, University of Maryland School of Medicine.

They will be discussing the paper, “Clinical Significance of Isolated Atypical Transient Symptoms in a Cohort With Transient Ischemic Attack,” published in the June 2017 issue of Stroke.

Dr. Merino: Could you please briefly summarize the key findings and put them into context of what was known before you did the study?

Dr. Lavallée: Conventional wisdom considers that some transient symptoms such as diplopia, vertigo, dysarthria and even a sensory deficit limited to one limb or the face are not compatible with the diagnosis of TIA when they occur in isolation. Daily experience in the stroke unit and TIA clinic shows that it is not true. In our study, we enrolled 1,850 patients seen in our TIA clinic who had transient symptoms and found that 10% of the patients with stroke or TIA had one of these isolated atypical symptoms and that 10% of the patients with atypical symptoms had an acute infarct on brain MRI and 18% had an underlying disease that placed them at high risk of stroke recurrence.

Prehospital Triage and the Race Against Time

Kevin S. Attenhofer, MD

Schlemm E, Ebinger M, Nolte C, Endres M, Schlemm L. Optimal Transport Destination for Ischemic Stroke Patients with Unknown Vessel Status: Use of Prehospital Triage Scores. Stroke. 2017

The spectrum of acute ischemic stroke (AIS) care begins well before the emergency room. EMS first responders are often the first to examine the patient and consider the diagnosis of stroke. There are multiple triage scores and systems in place to assist EMS. Options include the Cincinnati Prehospital Stroke Scale (CPSS), Face Arm Speech Test (FAST), Los Angeles Prehospital Stroke Screen (LAPSS), etc. Most of these scales focus on identifying common findings of subcortical strokes (facial droop, hemiparesis). In 2014, Spanish researchers created and published the Rapid Arterial Occlusion Evaluation (RACE) Scale, which included cortical, as well as subcortical, exam findings to aid with pre-hospital identification of patients with higher likelihood of having a large vessel occlusion (LVO). In addition to facial palsy and hemiparesis, the RACE scale also scores gaze deviation, aphasia, and agnosia.

Clinical implications of the RACE scale are unclear. One ongoing clinical trial, RACECAT, is comparing direct transfer of patients with a high RACE score (> 4) to an endovascular center versus taking these patients to the closest acute stroke center (without endovascular capabilities) with subsequent “drip and ship” of patients determined to have an LVO. With those results not expected until 2020, Schlemm et al have implemented a conditional probabilistic model to calculate probabilities of good outcome (modified Rankin Scale ≤ 2 after 3 months) for triage of AIS patients with unknown vessel status to either a “mothership” approach (direct to endovascular center) or “drip and ship” approach.

Author Interview: Seung-Hoon Lee, MD, PhD

Seung-Hoon Lee

Seung-Hoon Lee

A conversation with Seung-Hoon Lee, MD, PhD, Professor of Neurology, Seoul National University Hospital, about the role of the susceptibility vessel sign on SWI to predict stroke subtype and recanalization.

Interviewed by José G. Merino, MD, Associate Professor of Neurology, University of Maryland School of Medicine.

They will be discussing the paper, “Prediction of Stroke Subtype and Recanalization Using Susceptibility Vessel Sign on Susceptibility-Weighted Magnetic Resonance Imaging,” published in the June 2017 issue of Stroke.

Dr. Merino: Could you please briefly describe the study and summarize the key findings, putting them into context of what was known before you did the study?

Dr. Lee: I’m glad to talk about our research in this interview. Thrombi in the cerebral arteries appear hypointense on susceptibility-weighted MRI (SWMRI). We call them “the susceptibility vessel sign” (SVS). The methodological strength of this study is that SWI MRI is much more sensitive than GRE and thus can quantify the size of the SVS. In this study, we analyzed the relationship between the size of the SVS, the stroke mechanism, and whether successful recanalization occurred in patients receiving endovascular treatment. Cardiac emboli are large but fragile because they are rich in RBCs but have scant platelets. We hypothesized that because the SVS reflects the red blood cell component of the clot, patients with larger SVS are more likely to have a cardioembolic source and thus more likely to have successful recanalization. We found that as the SVS size increased, the probability of cardioembolic stroke was higher, but that SVS size did not show any positive or negative correlation with successful recanalization. This is probably due to the high recanalization rate with the stent-retrievers, irrespective of stroke etiology. No association between SVS size and recanalization can be partly explained by clot fragility in cardioembolic stroke.

Getting Stroke Patients to the Right Hospital — Fast: The FAST-ED Smartphone App

Neal S. Parikh, MD

Nogueira RG, Silva GS, Lima FO, Yeh Y, Fleming C, Branco D, et al. The FAST-ED App: A Smartphone Platform for the Field Triage of Patients With Stroke. Stroke. 2017

Time is brain, and we know it. Yet, stroke systems of care — particularly in the pre-hospital EMS domain — have yet to adapt to the latest and greatest in stroke: endovascular therapy (EVT). For every 8 or so patients treated with endovascular therapy, one patient achieves functional independence despite having suffered an acute, large-vessel occlusion (LVO).1 It behooves us, then, to develop stroke systems of care that deliver patients efficiently and rapidly to centers that provide EVT without compromising care for the remaining patients who would benefit from prompt IV-TPA. Everyone, from the AHA/ASA to endovascular therapy trialists, recognizes this need.

On my count, this is at least the fifth publication in Stroke in 2017 that seeks to meet this need. Others have queried whether the direct-to-mothership model is superior to the drip-and-ship model,2 whether the volume of EVT cases at an individual center impacts outcomes,3 and whether computer modeling can be used to define the catchment area of a hub.4 This all boils down to the key quandary: How should EMS triage and transport patients from the field?

Predicting Hemorrhagic Transformation Following tPA Using CT and CT Perfusion Images

Sami Al Kasab, MD

Batchelor C, Pordeli P, d’Esterre CD, Najm M, Al-Ajlan FS, Boesen ME, et al. Use of Noncontrast Computed Tomography and Computed Tomographic Perfusion in Predicting Intracerebral Hemorrhage After Intravenous Alteplase Therapy. Stroke. 2017

Intracerebral hemorrhage (ICH) is a known complication of intravenous alteplase. The rates of symptomatic intracerebral hemorrhage following intravenous alteplase administration have varied between 1-4% depending on the definition used and the study.

In this study, Drs. Connor et al analyze the association between multimodal CT imaging parameters, including NCCT hypo attenuation degree, vlCBV, impaired blood-brain barrier permeability surface product, clinical and laboratory data at baseline, early reperfusion status, and development of parenchymal hemorrhage (PH) on follow-up imaging. All patients received NCCT, CT angiography, and CT perfusion at baseline. A 24 to 48 hour scan (either NCCT or MRI) was obtained. Imaging analyses were performed by readers blinded to other imaging and patient outcomes. All NCCT were scored for ASPECTS scores, the degree of hypo attenuation within the ischemic region using a 3-point grading system. Functional parametric maps of cerebral blood flow (CBF), CBV, Tmax, and a modified CTP algorithm for permeability calculations were used.

Resistant Atherosclerosis

Philip Chang, MD

Spence JD, Solo K. Resistant Atherosclerosis: The Need for Monitoring of Plaque Burden. Stroke. 2017

In this study, Spence and Solo demonstrated that measurement of LDL-C levels is likely inadequate to assess a patient’s response to statin therapy. In their database of 4512 patients with 2 measurements of LDL-C and 2 carotid duplex scans measuring total plaque area, they found that neither LDL-C levels nor change in LDL-C levels predicted carotid artery plaque burden or progression of plaque area. Interestingly, they found that in the 6% of patients with low LDL-C levels (<38mg/dL), almost half experienced progression of their plaque burden. In addition, they found that it was not uncommon for patients with LDL-C levels of over 70mg/dL to experience plaque regression. This suggests that merely relying on an LDL-C level to predict plaque burden is insufficient.

Carotid Stenting vs. Endarterectomy: Vascular Anatomy Predicts Stroke Risk

Hatim Attar, MD

Müller MD, Ahlhelm FJ, von Hessling A, Doig D, Nederkoorn PJ, Macdonald S, et al. Vascular Anatomy Predicts the Risk of Cerebral Ischemia in Patients Randomized to Carotid Stenting Versus Endarterectomy. Stroke. 2017

There has been a longstanding debate on management of patients with carotid disease. In the ICSS study, patients were randomly assigned to Carotid Artery Stent (CAS) vs. Carotid Endarterectomy (CEA). CAS was related to higher peri-procedural stroke risk, but both therapies were equally effective in long-term stroke prevention. This study is a post-hoc analysis on a sub group of the ICSS study, providing the first randomized trial on vascular anatomy as an independent procedural risk factor for stroke during CAS and CEA. Studies have been completed assessing vascular anatomy for procedural risks with CAS, but none have compared the risk between CAS and CEA, making this study unique and its results invaluable.

In the ICSS MRI subgroup, brain MRI was performed before and 1-3 days after CAS or CEA; primary outcome was new diffusion restricted lesions. Patients in this study underwent Contrast Enhanced Magnetic Resonance Angiography (CE- MRA) or Computed Tomographic Angiography (CTA) to define vascular anatomy. Vascular anatomy was objectified with measurable criteria. Aortic arches were divided into three types based on origins of supra aortic arteries, and angles between all large vessels were defined, as shown below in the images.

 The authors validated the inter-rater reliability on reading these anatomic parameters. Associations were made between the laterality, stenosis length and degree, plaque ulcerations and vasculature angles.

There were 184 patients with vessel imaging; 97 were assigned to CAS, 87 to CEA. Procedural cerebral ischemia was found in 49 of the CAS group (51%), with only 14 after CEA (16%). After correcting for age, only two factors were found to be statistically significant in the CAS group—aortic arch configuration type 2 and 3, and larger ICA angulation (≥ 60 degrees).