Annual Review of Medicine - Volume 39, 1988

Swallowing is a coordinated activity that enables solids and liquids to pass uninterruptedly from the mouth to the stomach. Dysphagia occurs when this process is disrupted by organic or functional alterations at the level of swallow initiation or esophageal emptying. The differential diagnosis includes obstructive lesions and motility disorders. Symptoms and clinical features help distinguish these diseases.

Parathyroid localization tests are helpful for all patients with primary hyperparathyroidism before parathyroid exploration, and they are essential for patients who have had previous parathyroid or thyroid operations. The selection of specific localization tests depends on whether the patient is undergoing an initial or a reoperative procedure, as well as on the availability of the specialized equipment and expertise of the physicians and technicians performing and interpreting these studies.

Atrial fibrillation is a clinically important arrhythmia that carries important prognostic and therapeutic implications. Hypertension, ischemic heart disease, and rheumatic valvular disease are the commonest causes of atrial fibrillation. The presence of chronic or paroxysmal atrial fibrillation places the patient at increased risk for embolic stroke and/or death. When atrial fibrillation develops, there is loss of the atrial transport factor (“atrial kick”), with consequent decrease of cardiac output. Stroke output declines by 20-30% in normal individuals with loss of atrial kick; the decline in stroke output is considerably larger in patients with heart disease. Atrial fibrillation can be electrically or pharmacologically reverted to sinus rhythm. Even patients with refractory atrial fibrillation can be reverted to sinus rhythm with amiodarone.

Subcortical dementia occurs both in disorders affecting the basal ganglia (for example, Parkinson's disease, Huntington's disease, and progressive supranuclear palsy) and in a variety of subcortical vascular, infectious, inflammatory, neoplastic, and traumatic conditions. The principal features of subcortical dementia include bradyphrenia, impairment of executive function, recall abnormalities, visuospatial disturbances, depression, and apathy. The syndrome contrasts with dementia of the Alzheimer type in which cortical involvement produces aphasia, combined recall and recognition deficits, and indifference. Electrophysiologic, biochemical, and metabolic studies support a distinction between subcortical and cortical dementias.

Immunocompromised patients are prone to develop certain malignancies, particularly involving cells of the immune system itself (1-3). In this chapter we describe the various neoplasms, note the differences between these and similar cancers in the general population, emphasize similar tumor patterns in different types of immunodeficiency, and discuss possible etiologic factors.

Clinical judgment and noninvasive radiologic imaging are the keystones to decision-making in the management of most patients with asymptomatic liver lesions. A knowledge of the natural history of the common lesions suggests a conservative approach to those that are benign and an aggressive approach to those that are malignant and still localized.

Recent studies using experimental models of acute pancreatitis suggest that events blocking evoked secretion of digestive enzymes from acinar cells may play an important role in the pathogenesis of this disease. Under these conditions, digestive enzymes become co-localized with lysosomal hydrolases within large intracellular vacuoles, where activation of trypsin by the lysosomal enzyme cathepsin B could initiate the cascade activation of the other pancreatic zymogens. Development of acute pancreatitis might, therefore, be initiated by events occurring within acinar cells rather than in the ductal system or the interstitium of the gland.

After a pathogen has been identified and the antibiotic susceptibility determined, parenteral antibiotic administration can be replaced by the oral route for certain patients with meningitis, brain abscess, endocarditis, and skeletal infections. Antibiotics should be administered with the stomach empty and accompanied by 3 ml/kg of water. Direct instillation into the lumen of the small intestine may be advantageous with selected patients. Documenting adequate antibiotic absorption and ensuring compliance are essential to efficacious therapy.

Antiphospholipid antibodies may be detected by solid phase anticardiolipin antibody tests, the lupus anticoagulant test, or standard tests for syphilis (STS). The occurrence of these antibodies has been associated with venous or arterial thrombosis, fetal loss, and possibly thrombocytopenia. Other suggested features that may be associated with these antibodies include livedo reticularis, migraine, chorea, and heart valve lesions. Uncontrolled studies of small numbers of affected women with recurrent fetal loss suggest that prednisone and aspirin therapy during pregnancy may improve pregnancy outcome. Anticoagulant therapy is recommended for patients with thrombosis for as long as antiphospholipid antibodies persist.

Brain imaging is increasingly applied in psychiatry, both for clinical evaluation and as a research tool. Computerized tomography (CT) and magnetic resonance imaging (MRI) have documented that structural brain abnormalities occur in some types of psychiatric patients, particularly those who suffer from schizophrenia. Dynamic imaging techniques such as single-photon emission computed tomography (SPECT) and positron emission tomography (PET) have documented decreased temporoparietal activity in Alzheimer’s disease, hypofrontality in schizophrenia, and a variety of abnormalities in affective and anxiety disorders. These techniques promise to teach us a great deal about the underlying neural mechanisms in mental illness.

Cochlear implantation, a form of neural prosthesis, is now being employed for some profoundly deaf individuals. The pathophysiology of profound deafness, the strategies inherent in cochlear implantation, the differences between various cochlear implant strategies and designs, medical and otologic evaluation of implant candidates, and the surgical procedure are each discussed. The results in speech recognition and speech reading that have been obtained with four commonly used cochlear implant systems are also presented.

Dyspnea, the sensation of feeling breathless, is a symptom experienced under conditions in which there is an inordinately high ventilatory demand relative to the ability to breathe. Its major physical sign is tachypnea. New developments in monitoring ventilation during exercise have improved our ability to evaluate the symptom of dyspnea and to understand pathophysiological mechanisms contributing to the symptom. We briefly describe the range of mechanisms that determine exercise ventilation and their possible relationship to dyspnea. Questionnaires and psychophysical testing have been used to quantify dyspnea, but there is variability in dyspnea grade from these methods. Dyspnea-producing stimuli and the mechanisms by which they act are reviewed. Disorders producing dyspnea and the pathophysiological mechanisms underlying each are discussed. Perception of dyspnea is obviously through the central nervous system, where dyspnea-producing stimuli are integrated. The specific integration site is probably in the region of the brain stem, since occasional patients with brain stem lesions do not experience dyspnea despite the presence of a number of dyspnea-producing stimuli.

Membranous nephropathy is the most common cause of idiopathic nephrotic syndrome in adults. Recent studies of the pathogenesis of the sub-epithelial glomerular immune deposits that characterize this disease have revealed new mechanisms of glomerular immune deposit formation involving cell surface antigens and have documented the role of the C5b-9 membrane attack complex of complement in mediating renal injury. Understanding these mechanisms may help us understand the pathogenesis of several other immune-mediated diseases and has implications for possible therapeutic interventions in MN.

Acute renal failure is a serious consequence of renal ischemia. The diagnosis carries an associated high mortality rate. When blood flow to the kidneys is inadequate to supply metabolic demands, a number of pathophysiological changes occur that ultimately result in cell death and tissue dysfunction, characterized by a marked reduction in glomerular filtration rate and associated accumulation of systemic toxins and disorders of fluid and electrolyte metabolism. In this chapter we review the factors that have been implicated as mediators of the renal tissue damage associated with ischemia and reperfusion.