الفهرس 
INTRODUCTION
Important definitionsOnly 14 pages are availabe for public view
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Abstract
Epidemiology is the basic science of preventive and social medicine. It is the study of the natural history of disease, which includes its frequency, severity, and course and the identification of “risk factors” that influence these aspects.
Neuroepidemiology is the application of the methods of epidemiology to the problems of clinical neurology.
The basic difference between epidemiology and clinical medicine is that in epidemiology, the unit of study is a ”defined population” or ”population at risk”; in clinical medicine, the unit of study is a ”case” or ”cases”.
There are challenges in the investigation of neurologic disease due to the specific characteristics of a neurological disorder as well as the special features of the nervous system, as many neurologic diseases are relatively rare.
The most important measurements in epidemiology are: Measurement of morbidity, Measurement of mortality and Measurement of natality.
Morbidity has been defined as ”any departure, subjective or objective, from a state of physiological well-being” Disease frequency is measured by incidence and prevalence rates.
Incidence rate is defined as ”the number of NEW cases occurring in a defined population during a specified period of time”.
While prevalence refers specifically to all current cases (old and new) existing at a given point in time, or over a period of time in a given population.
The primary concern of the epidemiologist is to study disease occurrence in people, who during the course of their lives are exposed to numerous factors and circumstances, some of which may have a role in disease a etiology, so the epidemiologist employs carefully designed research strategies to explore disease an etiology.
Epidemiological studies can be classified as observational studies and experimental studies with further subdivisions.
I Observational studies: allow nature to take its own course; the investigator measures but does not intervene. They include studies that can be called descriptive or analytical:
A) Descriptive study is limited to a description of the occurrence of a disease in a population.
B) An analytical study goes further by analyzing relationship between health status and other variables. The major analytical study designs are: cross- sectional study, cohort study, case- control study and ecologic study.
II Experimental or intervention studies: involve an active attempt to change a disease determinant or the progress of a disease, and are similar in design to experiments in other sciences. However, they are subject to extra constraints, since the health of the people in the study group may be at stake.
The major experimental design is the randomized controlled trial using patients as subjects.
Field trials and community trials are other experimental studies in which the participants are healthy people and community respectively.
Epidemiological investigations aim to provide accurate measures of disease occurrence (or other outcomes). However, there are many possibilities for errors in measurement. Sources of error can be random or systematic.
Approaches to prevention overlap and merge, yet all levels are important and complementary. Primordial and primary prevention contribute most to the health of the whole population, while secondary and tertiary prevention are generally focused on people who already have signs of disease. With specific reference to neurological disorders. Several types of interventions are possible through interventions in hospital and population based settings
Statistics is the science of the collection, organization, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments.
Data exist as either numerical or categorical variables.
Summary measures: They include: measures of central tendency and measures of dispersion (or variability). Such summary measures, calculated from a sample of data, are called sample statistics, or just statistics.
Statistical tests are several and they are depending on Hypothesis Testing, confidence interval, the ”p” value and Methods of analyzing the relationship between two quantitative variables which include correlation Coefficient and regression models.
After collection of data, they are summarized and displayed in form of Tables and graphs.
Tables and graphs are important means of summarizing and displaying data, but they are seldom prepared with sufficient care. Their purpose is to display data in a way that can be quickly and easily understood. Each table or graph should contain enough information so that it can be interpreted without reference to the text.
Screening is the process of using tests on a large scale to identify the presence of disease in apparently healthy people.
The screening test itself must be cheap, easy to apply, acceptable to the public, reliable and valid.
In recent years, a large number of laboratory tests are available for screening individuals with hypertension, diabetes, raised triglyceride levels, etc., in stroke prevention programmes.
Neurological diseases are increasingly recognized as a major public health problem especially in the developing world. The extension of life expectancy and the ageing of populations globally are predicted to increase the prevalence of many non-communicable, chronic, progressive conditions including neurological disorders.
The prevalence of various neurological disorders in the community is vital for planning of neurological services at local, national and global levels. In spite of epidemiology of neurological disorders is still lacking in Egypt, Several studies on neurological diseases are carried out in different countries as Cairo, Assiut and Al- kharga discrete. The door-to-door method is the most suitable one to screen neurological disorders in our country.