Chronic Migraine: An Update on Diagnosis and Management.

Background: Chronic migraine is an under-recognized and under-treated disorder. A greater understanding of the pathophysiology of migraine and transformation to chronic migraine has led to the first targeted treatments for chronic migraine. In this review, we review current approaches to the diagnosis and management of chronic migraine and discuss recent and emerging novel therapies.

Respiratory challenge MRI: Practical aspects.

Respiratory challenge MRI is the modification of arterial oxygen (PaO2) and/or carbon dioxide (PaCO2) concentration to induce a change in cerebral function or metabolism which is then measured by MRI. Alterations in arterial gas concentrations can lead to profound changes in cerebral haemodynamics which can be studied using a variety of MRI sequences. Whilst such experiments may provide a wealth of information, conducting them can be complex and challenging.

Oxygen challenge magnetic resonance imaging in healthy human volunteers.

Oxygen challenge imaging involves transient hyperoxia applied during deoxyhaemoglobin sensitive (T2*-weighted) magnetic resonance imaging and has the potential to detect changes in brain oxygen extraction. In order to develop optimal practical protocols for oxygen challenge imaging, we investigated the influence of oxygen concentration, cerebral blood flow change, pattern of oxygen administration and field strength on T2*-weighted signal. Eight healthy volunteers underwent multi-parametric magnetic resonance imaging including oxygen challenge imaging and arterial spin labelling using two oxygen concentrations (target FiO of 100 and 60%) administered consecutively (two-stage challenge) at both 1.

Derivation and evaluation of thresholds for core and tissue at risk of infarction using CT perfusion.

Background And Purpose: Computed tomography perfusion provides information on tissue viability according to proposed thresholds. We evaluated thresholds for ischemic core and tissue at risk and subsequently tested their accuracy in independent datasets.

Materials And Methods: Tissue at risk was evaluated in patients with persistent arterial occlusions, and ischemic core thresholds in patients with recanalization and major clinical improvement.

Multi-center prediction of hemorrhagic transformation in acute ischemic stroke using permeability imaging features.

Permeability images derived from magnetic resonance (MR) perfusion images are sensitive to blood-brain barrier derangement of the brain tissue and have been shown to correlate with subsequent development of hemorrhagic transformation (HT) in acute ischemic stroke. This paper presents a multi-center retrospective study that evaluates the predictive power in terms of HT of six permeability MRI measures including contrast slope (CS), final contrast (FC), maximum peak bolus concentration (MPB), peak bolus area (PB), relative recirculation (rR), and percentage recovery (%R). Dynamic T2*-weighted perfusion MR images were collected from 263 acute ischemic stroke patients from four medical centers.

Rare neurological diseases: a practical approach to management.

Although neurologists are frequently faced with the management of rare diseases, there is little generic guidance for the approach to management. There are complexities with respect to diagnosis, counselling, treatment and monitoring which are idiosyncratic to rare diseases. Here we use a case report as the basis for discussion of the management of rare neurological diseases.

Multivoxel MR spectroscopy in acute ischemic stroke: comparison to the stroke protocol MRI.

Background And Purpose: Few patients with stroke have been imaged with MR spectroscopy (MRS) within the first few hours after onset. We compared data from current MRI protocols to MRS in subjects with ischemic stroke.

Methods: MRS was incorporated into the standard clinical MRI stroke protocol for subjects <24 hours after onset.

Crossed cerebellar diaschisis: insights into oxygen challenge MRI.

Hyperoxia during T2*-weighted magnetic resonance imaging (oxygen challenge imaging (OCI)) causes T2*-weighted signal change that is dependent on cerebral blood volume (CBV) and oxygen extraction fraction (OEF). Crossed cerebellar diaschisis (CCD), where CBV is reduced but OEF is maintained, may be used to understand the relative contributions of OEF and CBV to OCI results. In subjects with large hemispheric strokes, OCI showed reduced signal change in the contralesional cerebellum (P=0.

Pilot results of in vivo brain glutathione measurements in stroke patients.

Measurement of glutathione concentration for the study of redox status in subjects with neurological disease has been limited to peripheral markers. We recruited 19 subjects with large strokes. Using magnetic resonance spectroscopy we measured brain glutathione concentration in the stroke region and in healthy tissue to calculate a glutathione-ratio.

Systematic review of perfusion imaging with computed tomography and magnetic resonance in acute ischemic stroke: heterogeneity of acquisition and postprocessing parameters: a translational medicine research collaboration multicentre acute stroke imaging study.

Background And Purpose: Heterogeneity of acquisition and postprocessing parameters for magnetic resonance- and computed tomography-based perfusion imaging in acute stroke may limit comparisons between studies, but the current degree of heterogeneity in the literature has not been precisely defined.

Methods: We examined articles published before August 30, 2009 that reported perfusion thresholds, average lesion perfusion values, or correlations of perfusion deficit volumes from acute stroke patients <24 hours postictus. We compared acquisition parameters from published studies with guidance from the Acute Stroke Imaging Research Roadmap(1).

Computed tomography and magnetic resonance perfusion imaging in ischemic stroke: definitions and thresholds.

Objective: Cerebral perfusion imaging with computed tomography (CT) or magnetic resonance (MR) is widely available. The optimum perfusion values to identify tissue at risk of infarction in acute stroke are unclear. We systematically reviewed CT and MR perfusion imaging in acute ischemic stroke.

T2*-weighted magnetic resonance imaging with hyperoxia in acute ischemic stroke.

Objective: We describe the first clinical application of transient hyperoxia ("oxygen challenge") during T2*-weighted magnetic resonance imaging (MRI), to detect differences in vascular deoxyhemoglobin between tissue compartments following stroke.

Methods: Subjects with acute ischemic stroke were scanned with T2*-weighted MRI and oxygen challenge. For regions defined as infarct core (diffusion-weighted imaging lesion) and presumed penumbra (perfusion-diffusion mismatch [threshold = T(max) > or =4 seconds], or regions exhibiting diffusion lesion expansion at day 3), T2*-weighted signal intensity-time curves corresponding to the duration of oxygen challenge were generated.

Brain lesion volume and capacity for consent in stroke trials: potential regulatory barriers to the use of surrogate markers.

Background And Purpose: European directives and legislation in some countries forbid inclusion of subjects incapable of consent in research if recruitment of patients capable of consent will yield similar results. We compared brain lesion volumes in stroke patients deemed to have capacity to consent with those defined as incapacitated.

Methods: Data were obtained from 3 trials recruiting patients primarily with cortical stroke syndromes.