medical ebook, journal, and article free

HUGH CALKINS DOUGLAS P. ZIPES Syncope is a sudden transient loss of consciousness and postural tone with spontaneous recovery. Loss of consciousness results from a reduction of blood flow to the reticular activating system located in the brain stem and does not require electrical or chemical therapy for reversal. The metabolism of the brain, in contrast to that of many other organs, is exquisitely dependent on perfusion. Consequently, cessation of cerebral blood flow leads to loss of consciousness within approximately 10 seconds. Syncope is an important clinical problem because it is common, is costly, is often disabling, may cause injury, and may be the only warning sign before sudden cardiac death.[1] [2] [3] [4] [14A] [21A] [21B] [28A] Patients with syncope account for 1 percent of hospital admissions and 3 percent of emergency department visits.[1] Elderly persons have a 6 percent annual incidence of syncope. Surveys of young adults have revealed that up to 50 percent report a prio...

One learns quickly in dealing with such patients that not all pain is the consequence of serious disease. Every day, healthy persons of all ages have pains that must be taken as part of normal sensory experience. To mention a few, there are the “growing pains” of children; the momentary hard pain over an eye or in the temporal or occipital regions, which strikes with such suddenness as to raise the suspicion of a ruptured intracranial aneurysm; the more persistent ache in the fleshy part of the shoulder, hip, or extremity that subsides spontaneously or in response to a change in position; the fluctuant precordial discomfort of gastrointestinal origin, which conjures up fear of cardiac disease; the breathtaking “stitch in the side,” due to intercostal or diaphragmatic cramp. These normal pains, as they should be called, tend to be brief and to depart as obscurely as they came. Such pains come to notice only when elicited by an inquiring physician or when experienced by a patient given t...

The stimuli that activate pain receptors vary from one tissue to another. As pointed out above, the adequate stimulus for skin is one that has the potential to injure tissue, i.e., pricking, cutting, crushing, burning, and freezing. These stimuli are ineffective when applied to the stomach and intestine, where pain is produced by an engorged or inflamed mucosa, distention or spasm of smooth muscle, and traction on the mesenteric attachment. In skeletal muscle, pain is caused by ischemia (the basis of intermittent claudication), necrosis, hemorrhage, and injection of irritating solutions, as well as by injuries of connective tissue sheaths. Prolonged contraction of skeletal muscle evokes an aching type of pain. Ischemia is also the most important cause of pain in cardiac muscle. Joints are insensitive to pricking, cutting, and cautery, but pain can be produced in the synovial membrane by inflammation and by exposure to hypertonic saline. The stretching and tearing of ligaments around a ...

Historical Perspective For more than a century, views on the nature of pain sensation have been dominated by two major theories. One, known as the specificity theory, was from the beginning associated with the name of von Frey. He asserted that the skin consisted of a mosaic of discrete sensory spots and that each spot, when stimulated, gave rise to one sensation—either pain, pressure, warmth, or cold; in his view, each of these sensations had a distinctive end organ in the skin and each stimulus-specific end organ was connected by its own private pathway to the brain. A second theory was that of Goldscheider, who abandoned his own earlier discovery of pain spots to argue that they simply represented pressure spots, a sufficiently intense stimulation of which could produce pain. According to the latter theory, there were no distinctive pain receptors, and the sensation of pain was the result of the summation of impulses excited by pressure or thermal stimuli applied to the skin. Origin...

Maurice Victor, Allan H. Ropper, Raymond D. Adams This common disease, known since ancient times, was first cogently described by James Parkinson in 1817. In his words, it is characterized by “involuntary tremulous motion, with lessened muscular power, in parts not in action and even when supported; with a propensity to bend the trunk forward, and to pass from a walking to a running pace, the senses and intellect being uninjured.” Strangely, his essay contains no reference to rigidity or to slowness of movement, and it stresses unduly the reduction in muscular power. The same criticism can be leveled against the term paralysis agitans, which appeared for the first time in 1841, in Marshall Hall's textbook Diseases and Derangements of the Nervous System. Certain aspects of the natural history of the disease are of interest. As a rule, it begins between 40 and 70 years of age, with the peak age of onset in the sixth decade. It is infrequent before 30 years of age (only 4 of 380 cases...