Persistent perfusion abnormalities at day 1 correspond to different clinical trajectories after stroke.

BACKGROUND: Perfusion abnormalities after thrombolysis are frequent within and surrounding ischemic lesions, but their relative frequency is not well known. OBJECTIVE: To describe the different patterns of perfusion abnormalities observed at 24 hours and compare the characteristics of the patients according to their perfusion pattern. METHODS: From our thrombolysis registry, we included 226 consecutive patients with an available arterial spin labeling (ASL) perfusion sequence at day 1. We performed a blinded assessment of the perfusion status (hypoperfusion-h, hyperperfusion-H, or normal-N) in the ischemic lesion and in the surrounding tissue. We compared the time course of clinical recovery, the rate of arterial recanalization, and hemorrhagic transformations in the different perfusion profiles. RESULTS: We identified seven different perfusion profiles at day 1. Four of these (h/h, h/H, H/H, and H/N) represented the majority of the population (84.1%). The H/H profile was the most frequent (34.5%) and associated with 3-month good outcome (modified Rankin Scale (mRS): 63.5%). Patients with persistent hypoperfusion within and outside the lesion (h/h, 12.4%) exhibited worse outcomes after treatment (mRS score 0-2: 23.8%) than other patients, were less frequently recanalized (40.7%), and had more parenchymal hematoma (17.8%). The h/H profile had an intermediate clinical trajectory between the h/h profile and the hyperperfused profiles. CONCLUSION: ASL hypoperfusion within the infarct and the surrounding tissue was associated with poor outcome. A more comprehensive view of the mechanisms in the hypoperfused surrounding tissue could help to design new therapeutic approaches during and after reperfusion therapies.

Retrospective Observational Study of Brain MRI Findings in Patients with Acute SARS-CoV-2 Infection and Neurologic Manifestations.

Background This study provides a detailed imaging assessment in a large series of patients infected with coronavirus disease 2019 (COVID-19) and presenting with neurologic manifestations. Purpose To review the MRI findings associated with acute neurologic manifestations in patients with COVID-19. Materials and Methods This was a cross-sectional study conducted between March 23 and May 7, 2020, at the Pitié-Salpêtrière Hospital, a reference center for COVID-19 in the Paris area. Adult patients were included if they had a diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with acute neurologic manifestations and referral for brain MRI. Patients with a prior history of neurologic disease were excluded. The characteristics and frequency of different MRI features were investigated. The findings were analyzed separately in patients in intensive care units (ICUs) and other departments (non-ICU). Results During the inclusion period, 1176 patients suspected of having COVID-19 were hospitalized. Of 308 patients with acute neurologic symptoms, 73 met the inclusion criteria and were included (23.7%): thirty-five patients were in the ICU (47.9%) and 38 were not (52.1%). The mean age was 58.5 years ± 15.6 [standard deviation], with a male predominance (65.8% vs 34.2%). Forty-three patients had abnormal MRI findings 2-4 weeks after symptom onset (58.9%), including 17 with acute ischemic infarct (23.3%), one with a deep venous thrombosis (1.4%), eight with multiple microhemorrhages (11.3%), 22 with perfusion abnormalities (47.7%), and three with restricted diffusion foci within the corpus callosum consistent with cytotoxic lesions of the corpus callosum (4.1%). Multifocal white matter-enhancing lesions were seen in four patients in the ICU (5%). Basal ganglia abnormalities were seen in four other patients (5%). Cerebrospinal fluid analyses were negative for SARS-CoV-2 in all patients tested (n = 39). Conclusion In addition to cerebrovascular lesions, perfusion abnormalities, cytotoxic lesions of the corpus callosum, and intensive care unit-related complications, we identified two patterns including white matter-enhancing lesions and basal ganglia abnormalities that could be related to severe acute respiratory syndrome coronavirus 2 infection. © RSNA, 2020 Online supplemental material is available for this article.

Specificities of arterial spin labeling (ASL) abnormalities in acute seizure.

PURPOSE: Arterial spin labeling (ASL) is a non-invasive tool measuring cerebral blood flow (CBF) and is useful to assess acute neurological deficit. While acute stroke presents as hypoperfused vascular territory, epileptic activity causes cortical hyperperfusion. Other neurological conditions exhibit hyperperfusion, like migraine or secondary "luxury perfusion" in strokes. Our objectives were to evaluate the usefulness and potential specificities of ASL in acute seizure and correlate it with electroencephalogram. MATERIALS AND METHODS: Amongst a cohort of patients with neurological deficit, addressed for suspicion of stroke, we retrospectively reviewed 25 consecutive patients with seizures who underwent magnetic resonance imaging (MRI) with ASL and electroencephalography (EEG). We compared them with a control group of patients with migraine and stroke secondary re-perfusion, exhibiting ASL hyperperfusion. RESULTS: Lateralized cortical hyperperfusion (high relative CBF) was observed in all patients. Good topographic correlation with EEG was found in 18 patients (72%). Eight (32%) had hyperperfusion of ipsilateral pulvinar, 5 (20%) had hyperperfused contralateral cerebellar hemisphere, 16 (64%) presented diffusion abnormalities and 20 (80%) had underlying epileptogenic lesions. Pulvinar hyperperfusion was not observed in the control group, nor were diffusion abnormalities in migrainous patients. Contralateral cerebellar hyperperfusion was observed in two migrainous patient, without associated pulvinar activation, whereas all patients with cerebellar hyperperfusion in the study group had associated pulvinar activation. CONCLUSIONS: Elevated CBF can be observed in the epileptogenic zone, ipsilateral pulvinar and contralateral cerebellum (diaschisis) in seizure. These abnormalities seem specific when compared with other causes of hyperperfusion. Arterial spin labeling can be highly effective in the differential diagnosis of strokes.

Influence of MVC on Temporal and Spectral Features of Simulated Surface Electromyographic Signals.

The main aim of the present study was to examine the effect of the maximum voluntary contraction (MVC) on the mean absolute value (MAV) and on the median frequency (MDF) of simulated surface electromyographic (sEMG) signals generated in a cylindrical, multilayer, volume conductor constituted by bone, muscle, fat, and skin layers and detected by the longitudinal single (LSD) and double (LDD) differential systems. The study was made for two values (5 and 10 mm) of the interelectrode distances (IED) and three values (20, 25, and 30 Hz) of the peak firing rate (PFR) of the first recruited motor unit (MU) in the case of narrow (30%) and broad (70%) recruitment ranges (RRs) of MU when the MVC level varied from 10% to 100% in steps of 10%. The results show that an increase of MVC level leads to an increase of MAV and a decrease of MDF of the simulated sEMG signals. Moreover, for the same RR of MU, the MAV values were larger for the large IED and the large PFR. However, with the MDF values, inverse results were obtained.

Relationship between watershed infarcts and recent intra plaque haemorrhage in carotid atherosclerotic plaque.

OBJECTIVE: Watershed infarcts (WSI) are thought to result from hemodynamic mechanism, but studies have suggested that microemboli from unstable carotid plaques may distribute preferentially in watershed areas, i.e., between two cerebral arterial territories. Intraplaque haemorrhage (IPH) is an emerging marker of plaque instability and microembolic activity. We assessed the association between WSI and IPH in patients with recently symptomatic moderate carotid stenosis. METHODS AND RESULTS: We selected 65 patients with symptomatic moderate (median NASCET degree of stenosis = 31%) carotid stenosis and brain infarct on Diffusion-Weighted Imaging (DWI) on Magnetic Resonance Imaging (MRI) from a multicentre prospective study. Fourteen (22%) had WSI (cortical, n = 8; internal, n = 4; cortical and internal, n = 2). Patients with WSI were more likely to have IPH than those without WSI although the difference was not significant (50% vs. 31%, OR = 2.19; 95% CI, 0.66-7.29; P = 0.20). After adjustment for degree of stenosis, age and gender, the results remained unchanged. CONCLUSION: About one in fifth of brain infarcts occurring in patients with moderate carotid stenosis were distributed in watershed areas. Albeit not significant, an association between IPH--more generally plaque component--and WSI, still remains possible.