Stroke pathology

Increase in the proportion of patients identified by MRI that benefit from treatment Increase in the proportion of patients with a specific stroke pathology identified by MRI Sensitivity, specificity, and prospective values of MRI for a specific stroke pathology compared to a reference standard, assessment of validity... 

Interobserver agreement in assessing a specific stroke pathology on MRI, proportion of patients who can tolerate examination with MRI... 

The dual concept of presenting MR imaging of stroke pathology and MR correlates of stroke syndromes has led to the division of this volume into two parts (Parts 2 and 3), preceded by Part 1 with introductory chapters on clinically relevant syndromes and information on the clinical and therapeutic efficacy of MR imaging. We hope that readers will find it intriguing to use the book and will always feel free to inform us about ways to improve this work... 

Although stroke onset is usually abrupt, the neurological deficit often worsens over the following minutes, hours and sometimes days. Deterioration may be caused by neurological factors (Table 16.3) or systemic factors (Table 16.4) (Karepov et al. 2006) but progressive non-stroke pathologies should also be reconsidered. 

A systemic inflammatory response involving up-regulation of TNF-a and IL-1 is believed to be instrumental in the formation and destabilization of plaques, one of the risk factors for ischemic stroke (Emsley and Tyrrell, 2002 Hansson and Libby, 2006). There is considerable clinical data indicating that this systemic inflammation is associated with unfavorable outcome in stroke patients (McColl et al., 2007). However, this inter-relationship of systemic inflammation with stroke pathology has not been well studied. 

The modern period in the history of stroke began in the 1960s when C. Miller Fisher described detailed clinical and pathological observations on the features of lacunar strokes, carotid artery disease, transient ischemic attacks, and intracerebral hemorrhage. His student Louis Caplan established one of the first stroke registry... 

Cardioembolism Cardioembolism accounts for approximately 30% of all stroke and 25-30% of strokes in the young (age <45 years)." AF accounts for a large proportion of these strokes (15-25%). Symptoms may be suggestive, but they are not diagnostic. Repetitive, stereotyped, transient ischemic attacks (TIAs) are unusual in embolic stroke. The classic presentation for cardioembolism is the sudden onset of maximal symptoms. The size of the embolic material determines, in part, the course of the embolic material. Small emboli can cause retinal ischemic or lacunar symptoms. Posterior cerebral artery territory infarcts, in particular, are often due to cardiac embolism. This predilection is not completely consistent across the various cardiac structural abnormalities that predispose to stroke, and may be due to patterns of blood flow associated with specific cardiac pathologies. 

Many patients have a rhythm that varies between atrial flutter and AF. Atrial flutter is associated with a 40% higher risk of stroke. Given that the concordance of the AF and atrial flutter is high, anticoagulation should be considered in patients with atrial flutter and coexisting cardiac pathology predisposing to left atrial thrombus. 

History of prior ischemic stroke greater than 3 months ago, dementia, or known intracranial pathology not covered above under absolute contraindications... 

Neuropathic pain is defined as spontaneous pain and hypersensitivity to pain associated with damage to or pathologic changes in the peripheral nervous system as in painful diabetic peripheral neuropathy (DPN), acquired immunodeficiency syndrome (AIDS), polyneuropathy, post-herpetic neuralgia (PHN) or pain originating in the central nervous system (CNS), that which occurs with spinal cord injury, multiple sclerosis, and stroke. Functional pain, a relatively newer concept, is pain sensitivity due to an abnormal processing or function of the central nervous system in response to normal stimuli. Several conditions considered to have this abnormal sensitivity or hyperresponsiveness include fibromyalgia and irritable bowel syndrome. 

Hypertension is the most common cardiovascular disease in fact, nearly 25% of adults in the U.S. are considered hypertensive. Hypertension is defined as a consistent elevation in blood pressure such that systolic/diastolic pressures are >140/90 mmHg. Over time, chronic hypertension can cause pathological changes in the vasculature and in the heart. As a result, hypertensive patients are at increased risk for atherosclerosis, aneurysm, stroke, myocardial infarction, heart failure, and kidney failure. There are several categories of antihypertensive agents ... 

While the role of PHD inhibitors in the treatment of anemia is now validated, therapeutic validation is less certain in other HIF-associated pathologies such as wound healing, ulcerative colitis, therapeutic angiogenesis, and treatment of acute ischemic events such as myocardial ischemia and stroke. All of these indications are supported by a compelling array of in vitro and in vivo preclinical studies but their utility in the clinical setting remains to be evaluated and represents exciting possibilities for the future of small-molecule inhibitors of PHD enzymes. 

The partial oxygen pressure, p02, is particularly significant in metabolic processes of cells, and its variation from normal values often indicates pathologies (ischemic diseases, strokes, tumors). Accurate and localized measurements of the oxygen concentration are also desirable for differentiation between venous and arterial blood, or for cerebral mapping of task activation. In the past, invasive methods were used involving oxygen-sensitive electrodes which had to be placed directly in the blood or tissue and could only offer p02 from a few body points. 

A thromboembolic diathesis is not unusual and strokes have been reported. Other pathological changes have included microgyri, demyelination, gliosis and brain atrophy. Lipid-laden macrophages have been described. 

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