The electrical discharge of neurons associated with seizure activity stimulates a marked rise in cerebral metabolic activity. Estimates from animal experiments indicate that energy utilization during seizures increases by more than 200", while tissue adenosine triphosphate (ATP) levels remain at more than 95" of control, even during prolonged status epilepticus. The brain generally withstands the metabolic challenge of seizures quite well because enhanced cerebral blood flow delivers additional oxygen and glucose. Mild to moderate degrees of hypoxemia that commonly accompany seizures are usually harmless. However, severe seizures and status epilepticus can sometimes produce an imbalance between metabolic demands and cerebral perfusion, especially if severe hypotension or hypoglycemia is present. A marked increase in glutamate release, which occurs during a prolonged seizure, is likely to result in the activation of all types of glutamate receptors. Although kainic acid produces seizures in the immature brain, it produces little cytotoxicity.
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Recent advancements in molecular genetics have expanded our understanding of the etiology of many neurological diseases and neurodevelopmental abnormalities. Having a comprehensive understanding of genetics is essential in treating patients with metabolic epilepsies. Genetic counseling has been defined as a process of helping people understand and adapt to the medical, psychological, and familial implications of genetic contributions to disease. Some of the components of a genetic counseling interaction include interpretation of family and medical histories to assess the chance of disease occurrence or recurrence; education about inheritance, testing, management, prevention, resources, and research; and counseling to promote informed choices and adaptation to the risk or condition. The genetic counselor may also educate patients and their families about the underlying genetics of their epilepsy and the relevance of a genetic cause of epilepsy for family members, including recurrence risk, reproductive options and the possible teratogenic effect of antiepileptic drugs.Source:
This chapter presents a brief review of the enzymes, transporters, and cofactor producers of the urea cycle. Seizures have long been associated with urea cycle disorders (UCDs), thought to be caused by high levels of ammonia. Furthermore, the brain damage obtained during metabolic crisis has been thought to damage critical structures, leading to epilepsy after the conclusion of the crisis. The first and most critical step of successful treatment of UCDs is recognition. Neurologic monitoring is an essential part of the emergency management of UCDs. The neurological abnormalities observed in patients with urea cycle defects are vast. Controlling ammonia levels by dialysis and complementary medication are needed. EEG monitoring should be initiated early, as this may be very useful for clinical management and indication of untreated metabolic crises. Furthermore, aggressive treatment of clinical and subclinical seizure activity may be helpful in optimizing outcomes for these patients.Source:
Clinical neurophysiology (CNP) is a time-honored medical specialty that continues to make great strides, bolstered by rapid advances in neuroscience, biomedical engineering, and computer technology. It encompasses a wide range of methods and techniques for recording, presenting, and analyzing neurophysiologic signals in order to diagnose sensory, motor, autonomic, and central nervous system disorders. Testing performed in CNP or procedures used in current neurological practice include a variety of modality-specific and mixed-modality tests. Modality-specific CNP tests are performed to assess specific functional modalities using biomedical instruments that measure changes in neurophysiologic signals that occur spontaneously or with activation. Mixed-modality CNP tests utilize two or more test modalities to assess complex states (e.g., sleep, coma), to track multiple physiologic parameters, or to obtain more accurate results. CNP tests are classified based on functional anatomy or neural pathway tested. This chapter discusses artifact recognition and presents sources of artifacts in clinical neurophysiologic testing.
- Go to chapter: Standing on the Shoulders of Giants: Personal Perspectives on Theory Development in Aging
This chapter provides a brief introduction to approaches to coping theory-from its early roots in psychodynamic defense mechanisms, through cognitive and personality approaches to coping styles, to more current work on coping and adaptive processes. The coping process approach recognizes that coping strategies are influenced not only by person characteristics such as personality, values, and developmental history but also by environmental demands and resources. The chapter develops a definition of ‘resilience’ as the ability to recognize, utilize, and develop or modify resources at the individual, community, and sociocultural levels in the service of three goal-related processes: maintenance of optimal functioning, given current limitations; development of a comfortable life structure; and development of a sense of purpose in life. A common assumption of life-span developmental theories is that the increasing physical and sometimes cognitive limitations with age necessitate changes in adaptive processes.
This chapter reviews biodemographic theories of aging that attempt to answer the proverbial ‘why’ and ‘how’ questions in gerontology. Biodemography of aging represents an area of research that integrates demographic and biological theory and methods and provides innovative tools for studies of aging and longevity. The historical development of the biodemography of aging is closely interwoven with the historical development of statistics, demography, and even the technical aspects of life insurance. The chapter also reviews some applications of reliability theory to the problem of biological aging. Reliability theory of aging provides theoretical arguments explaining the importance of early-life conditions in later-life health outcomes. Moreover, reliability theory helps evolutionary theories explain how the age of onset of diseases caused by deleterious mutations could be postponed to later ages during the evolution this could be easily achieved by simple increase in the initial redundancy levels.
This chapter describes the interpretive perspective in all its richness and variability in guiding research and advancing understanding of a wide range of phenomena in aging and life-course research. It discusses the interpretive perspective with other variants of social science theorizing, particularly normative perspectives on aging and life course-placing its development in historical context. The chapter addresses the contentious issue of causal explanation, as understood in diverse disciplinary contexts. It highlights some prominent normative theoretical approaches in social gerontology, by way of providing a comparative context for our primary consideration of the interpretive perspective. A given theoretical perspective in gerontology can focus solely on macro level, structural phenomena, on micro-level behavior and social interaction, or on understanding of the links between macro and micro phenomena.
This chapter traces the development of concepts and theories in the sociology of aging from the 1940s through the mid-1970s through seven themes. The first theme describes the importance of age in social structure and the place of the aged in changing societies. The second theme focuses on the issue of ‘successful aging’: how to define, measure, and achieve it. The third theme highlights the tension between social structure and individual agency in the activity versus disengagement theory controversy. The fourth theme concerns the social meanings of age, age cohorts, and generations, as well as interactions between age groups. The fifth theme focuses on families, aging, and intergenerational relations. The sixth theme of age stratification deals with the interplay between cohort succession and the aging of individuals. The seventh theme addresses the life course as a socially constructed process.
There can be little doubt that older people have today assumed a special place in the American social policy and political landscape. They constitute a large and growing population, they are increasingly well organized, and they are the recipients of public benefits that are the envy of every other social policy constituency in the nation. This chapter reviews and assesses different theoretical approaches that may help account in all or in part for these fairly recent and remarkable developments. The organization here centers on six distinct theoretical avenues for better understanding these political and policy developments: the logic of industrialization and policy development, the role of political culture and values, the presence of working-class mobilization, the impact of individual and group participation, the weight of state structure, and the effects of policy in shaping subsequent events.