Neuroimaging of stroke: a review

Cost burden of neuroimaging during one-time admission for first-ever acute stroke in Nigeria

Objectives:

To determine the cost burden of Neuroimaging and its contribution to direct total hospitalization costs (HCs) during one-time admission for first-ever stroke.

Methods:

The clinical characteristics, direct itemised costs and total HCs for 170 consecutive patients with first-ever stroke, admitted at our public tertiary health facility over a 15-month period were evaluated.

Results:

The records of 170 stroke subjects were reviewed. The median total HCs for one-time admission per stroke patient was $183.30 with a median daily cost of $15.86. Median cost of radiological investigations was the highest among the categorized hospital costs. Among the radiological investigations, neuroimaging accounted for at least 99% of cost to patients.

Conclusion:

The financial burden of radiological investigations, particularly neuroimaging, is high during one-time admission of patients with first-ever stroke in our environment.

Acute Ischaemic Stroke: Management, Recent Advances and Controversies

Acute ischaemic stroke is a major cause of death and disability. It may become an enormous burden to the patients themselves, their families as well as the health care systems. Patients at risk of airway, breathing and circulatory compromise should receive prompt resuscitation. Vital parameters and neurological status should be closely monitored. Attentions to blood pressure, temperature and sugar profile are important. The significance of early and correct diagnosis and subsequent treatment cannot be over-emphasised. There have been tremendous recent advances in different treatment modalities in acute stroke management. Various recanalisation modalities include intravenous and/or intra-arterial thrombolysis, acute defibrinogenation, anti-platelet treatment and anticoagulation. Carotid endarterectomy and endovascular strategies are recommended in selected patients. Advanced neuro-imaging techniques and neuroprotectants are being evaluated. Multidisciplinary stroke teams have been shown to improve patient survival and functional outcome. Pre-defined algorithms and protocols should be in place to expedite smooth and effective delivery of stroke service. Future directions should be aimed at exploring safer recanalisation modalities and extending the limit of the current 3-hour treatment window for thrombolysis.

Hemorrhagic cerebrovascular disease

Primary or nontraumatic spontaneous intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes, and has a poor prognosis. ICH has a mortality rate of almost 50% when associated with intraventricular hemorrhage within the first month, and 80% rate of dependency at 6 months from onset. Neuroimaging is critical in identifying the underlying etiology and thus assisting in the important therapeutic decisions. There are several imaging modalities available in the workup of patients who present with ICH, including computed tomography (CT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA). A review of the current imaging approach, as well as a differential diagnosis of etiologies and imaging manifestations of primary versus secondary intraparenchymal hemorrhage, is presented. Active bleeding occurs in the first hours after symptom onset, with early neurologic deterioration. Identifying those patients who are more likely to have hematoma expansion is an active area of research, and there are many ongoing therapeutic trials targeting this specific patient population at risk.

Dodecafluoropentane Emulsion (DDFPe) Decreases Stroke Size and Improves Neurological Scores in a Permanent Occlusion Rat Stroke Model

Background:

Dodecafluoropentane emulsion (DDFPe), given IV one hour after stroke, has been shown to greatly reduce the percent stroke volume (%SV) in rabbits. With repeated doses its effect continued for 24 hours.

Purpose:

Test DDFPe as neuroprotective agent in permanent occlusion rat stroke models in Sprague Dawley (SD) and Spontaneously Hypertensive Rats (SHR) measuring both %SV and neurological assessment scores (NAS).

Methods:

The male rats received either saline (control), or one or four doses (1x or 4x) of DDFPe (0.6ml/kg IV) one hour post stroke. Treatment groups were SD (n=26) (control, 1x and 4x; n=12, 7 and 7) and SHR (n=14) (control, 1x and 4x; n=7, 3 and 4). The 4x doses were given at 1.5 hour intervals. At six hours post stroke, the rats received a NAS using standard tests for balance, reflexes, and motor performance. Then rats were euthanized and brains removed for TTC evaluation of %SV.

Results:

For %SV analysis strain differences were not significant therefore strains were combined. DDFPe significantly decreased %SV in 1x and 4xDDFPe groups compared to control groups (2.59±1.81 and 0.98±0.88 vs. 9.24±6.06, p≤0.001 each; p≤0.0001 for the overall test for treatment effect). The 1x versus 4xDDFPe groups were not significantly different (p=0.40). In NAS analysis both strains showed significant improvement with 4xDDFPe therapy vs. controls, (SD: 5.00+2.45 vs. 9.36+3.56, p=0.01; SHR: 7.75+4.43 vs. 12.14+3.08, p=0.05). Differences between the 1x DDFPe group and controls were not significant (SD: 8.43+3.69; SHR: 9. 33+3.51).

Conclusion:

DDFPe treatment provides significant neuroprotection when assessed six hours post stroke.

Nanotechnology for the detection and therapy of stroke

Over the years, nanotechnology has greatly developed, moving from careful design strategies and synthesis of novel nanostructures to producing them for specific medical and biological applications. The use of nanotechnology in diagnostics, drug delivery, and tissue engineering holds great promise for the treatment of stroke in the future. Nanoparticles are employed to monitor grafted cells upon implantation, or to enhance the imagery of the tissue, which is coupled with a noninvasive imaging modality such as magnetic resonance imaging, computed axial tomography or positron emission tomography scan. Contrast imaging agents used can range from iron oxide, perfluorocarbon, cerium oxide or platinum nanoparticles to quantum dots. The use of nanomaterial scaffolds for neuroregeneration is another area of nanomedicine, which involves the creation of an extracellular matrix mimic that not only serves as a structural support but promotes neuronal growth, inhibits glial differentiation, and controls hemostasis. Promisingly, carbon nanotubes can act as scaffolds for stem cell therapy and functionalizing these scaffolds may enhance their therapeutic potential for treatment of stroke. This Progress Report highlights the recent developments in nanotechnology for the detection and therapy of stroke. Recent advances in the use of nanomaterials as tissue engineering scaffolds for neuroregeneration will also be discussed.

Altered global and regional brain mean diffusivity in patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common and progressive disorder accompanied by severe cardiovascular and neuropsychological sequelae, presumably induced by brain injury resulting from the intermittent hypoxia and cardiovascular processes accompanying the syndrome. However, whether the predominant brain tissue pathology is acute or chronic in newly-diagnosed, untreated OSA subjects is unclear; this assessment is essential for revealing pathological processes. Diffusion tensor imaging (DTI)-based mean diffusivity (MD) procedures can detect and differentiate acute from chronic pathology and may be useful to reveal processes in the condition. We collected four DTI series from 23 newly-diagnosed, treatment-naïve OSA and 23 control subjects, using a 3.0-Tesla magnetic resonance imaging scanner. Mean diffusivity maps were calculated from each series, realigned, averaged, normalized to a common space, and smoothed. Global brain MD values for each subject were calculated using normalized MD maps and a global brain mask. Mean global brain MD values and smoothed MD maps were compared between groups by using analysis of covariance (covariate: age). Mean global brain MD values were significantly reduced in OSA compared with controls (P = 0.01). Multiple brain sites in OSA, including medullary, cerebellar, basal ganglia, prefrontal and frontal, limbic, insular, cingulum bundle, external capsule, corpus callosum, temporal, occipital, and corona radiata regions showed reduced regional MD values compared with controls. The results suggest that global brain MD values are significantly reduced in OSA, with certain regional sites especially affected, presumably a consequence of axonal, glial, and other cell changes in those areas. The findings likely represent acute pathological processes in newly-diagnosed OSA subjects.

Stroke: epidemiology, classification, risk factors, complications, diagnosis, prevention, and medical and dental management

Cerebrovascular accident, or stroke, refers to an acute onset of neurologic deficits lasting more than 24 hours or culminating in death caused by a sudden impairment of cerebral circulation. Stroke is the third leading cause of death and a major cause of long-term disability in the United States. This article provides the dental community with an up-to-date understanding of the epidemiology, classification, risk factors, complications, diagnosis, prevention, and medical and dental management issues pertaining to stroke.

Advanced imaging application for acute ischemic stroke

With the approval of intravenous recombinant tissue plasminogen activator (r-TPA) in 1995, acute ischemic stroke therapy is increasingly being administered. Currently the approach to imaging these patients is very simplistic. Typically, noncontrast head computed tomography (CT) is the only study performed prior to treatment. Advanced imaging using CT or magnetic resonance imaging (MRI) can play a very important role in the triage and classification of patients with acute ischemic stroke. With knowledge of the location and size of the occlusion as well as the collateral circulation, the best treatment can be selected, minimizing any morbidity from treatment and maximizing the chance of success. The identification and stratification of patients according to their imaging and clinical features will further individualize treatment and allow tailored therapy. This review will discuss rapid imaging techniques that are easily available and the rationale for their use.

Pulmonary and cardiovascular consequences of smoking

The extensive worldwide disease burden attributable to tobacco smoking is reviewed, with particular attention to the epidemiologic and clinical aspects, molecular and cellular mechanisms, and pathophysiology of a variety of smoking-related pulmonary diseases, and the epidemiology and clinical presentation of smoking-related atherosclerotic disease as it affects the cardiovascular system cerebral circulation, the aorta, and the peripheral arterial tree.