Occam's razor, geriatric syndromes, and the dizzy patient.

In the 14th century, English philosopher William of Ockham (Occam) stated: Pluralitas non est ponenda sine necessitate, or Plurality must not be posited without necessity (1). In medicine, the application of Occam's razor, the concept of parsimony in diagnosis, has become firmly entrenched as a fundamental principle. For persons older than 65 years of age, howeverespecially those who experience dizzinessOccam's razor is often too sharp and cuts too narrowly to be the instrument of choice (2). Senescence, the age-related changes that result in increased vulnerability to impairment and disease and in decreased survival (3), results in at least one chronic illness in most of the Medicare population. The serial accumulation of additional ailments, and of medications for their treatment, is nearly universal with advancing age. The concept of geriatric syndromes (4) reflects the recognition of multifactorial disorders that plague the elderly in particular, as the functions of organs and the defenses against disease decline and impairments accumulate. Dizziness is often distressing to patients and frustrating to physicians because patients have trouble articulating their symptoms precisely and physicians have difficulty identifying and treating a specific disease responsible for the symptom (5, 6). This difficulty stems in large part from the frequently indirect relation between dizziness and any uniquely related disease process. Semantic issues aside, patients generally experience dizziness when the psychophysical mechanisms necessary for normal spatial orientation (7) fail: that is, when they are uncertain of their position or motion in space (8) . The term dizziness covers a multitude of evils that may impair or distort orienting sensations; degrade the integration of those sensations into a coherent picture; modify the performance of related motor acts; or affect the accurate sequential combination of these steps, interrupting the feedback loop necessary for such acts as walking, turning a corner, shopping in a supermarket, or riding a bicycle. Specific, single disorders certainly can cause dizzinessfor example, orthostatic hypotension, benign paroxysmal positional vertigo, or hyperventilationbut in many cases, especially in elderly persons, multiple disorders interact to impair spatial orientation. The underlying etiologies of such disorders may be varied. Consider the all-too-familiar dizzy patient who has cataracts, hearing loss, peripheral neuropathy, cervical spondylosis, and atrial fibrillation and takes a number of medications for these conditions. Opportunities for sensory, integrative, and motor distortions of orientation abound in such a patient, yet each of these disorders may have many etiologies. The relation between the physiologic mechanisms resulting in dizziness and the specific diseases at the root of these disorders is indirect. To understand and treat this common symptom, the physician must first tease out the physiologic disorders, then determine their etiology. In this issue, Tinetti and colleagues (9) report the results of their study of community-living elderly persons, of whom nearly one quarter experienced long-term, recurrent dizziness. The authors used questionnaires to assess patients' histories and symptoms; inventories to assess cognitive, affective, and anxiety disorders; measurements of blood pressure; and simple balance and hearing screening tests. They concluded that seven characteristics were at least marginally associated with dizziness: anxiety, depression, the use of five or more medications, impaired balance, past myocardial infarction, postural hypotension, and impaired hearing. Furthermore, the more of these characteristics that elderly patients had, the more likely they were to report dizziness. Tinetti and colleagues concluded that dizziness may often be a multifactorial problem, and, as such, it is similar to other geriatric syndromes, such as falling, delirium, and urinary incontinence (4). This study emphasizes an important and easily forgotten point: Dizziness, especially among elderly persons, is often due to multiple disorders involving multiple organ systems (10-12). For physicians who still cling to the misapprehension that dizziness is synonymous with vertigo and is invariably due to a disorder of the inner ear, this article should draw their attention to the broader nature of the symptom and the diversity of the conditions that may cause it. Tinetti and colleagues conducted an epidemiologic study, however, which should not be mistaken for a set of clinical guidelines for the evaluation of a dizzy patient. Epidemiologic studies have the virtue of facilitating statistical analysis, but at the expense of being limited to the use of whatever data have been collected. In a sense, the process is analogous to a person searching for his keys under a streetlight, regardless of where they may have been lost. In this paper, Tinetti and colleagues illuminate some of the conditions that are associated with dizziness in elderly persons. Rightly, they have found that some of these disorders may lead to dizziness, that others may be correlated with it, and that the association tends to be cumulative. In diagnosing dizziness, it is usually possible to identify relatively specific, distinctive symptoms; to determine sensory, integrative, or motor mechanisms responsible for the dizziness; and to identify one or more underlying disorders or diseases. To do so, however, the physician must ascertain the reliability of patients' reports, often by demonstrated example (such as the Dizziness Simulation Battery [6]). The physician must also evaluate vision, vestibular function, peripheral sensation, integrative ability, and motor function and must search specifically for such conditions as brainstem strokes, hypothyroidism, and cardiac arrhythmias. Only then can both the mechanism and the underlying etiology be reliably diagnosed. Surrogate and less specific measures will, of course, detect some of these problems but cannot distinguish the precise mechanisms or etiologies behind the problem. Results of simple balance tests might be abnormal in patients with vestibular disorders, for example, but these maneuvers would not differentiate vestibulopathy from a cerebellar infarct, an orthopedic problem, or peripheral neuropathy. A history of multiple drug use could identify dizziness produced by a central pharmacologic mechanism (90% of oral medications list dizziness as an adverse effect [13]) but might also reflect the presence of arthritis, a cardiac arrhythmia, diabetes, or some other condition. Thus, physicians take heed: The questions asked and maneuvers performed in Tinetti and colleagues' study are not intended to be the way you should go about diagnosing the cause of dizziness in your patients. You still must sort out the diagnosis by first analyzing the sensory, integrative, and motor mechanisms that cause a patient's spatial disorientation and then identifying the specific disease processes responsible for those disorders. What would change in the physician's approach to the elderly patient with dizziness if it is labeled a geriatric syndrome? The best result would be to underscore the likelihood that more than one problem contributes to the symptom. For those who are impressed with the risk of using Occam's razor for geriatric syndromes, the diagnosis and treatment of dizziness could be made more rational. But calling dizziness in the elderly a geriatric syndrome carries significant risk. If it implies to some physicians that dizziness is a usual concomitant of aging; that there may be no specific disease to identify, but instead undefinable erosions of mood or function; and that an evaluation might require only asking questions about the seven associated characteristics, they would be misled. It would be unfortunate if easily curable conditions (14) such as benign paroxysmal positioning vertigo were missed because the Hallpike maneuver was omitted. It would be tragic if a dizzy elderly patient with transient ischemic attacks of the posterior circulation or with a paroxysmal arrhythmia were considered to have a geriatric syndrome and did not get the specific treatment needed to avoid disaster. Dizziness is a common disorder, especially in elderly persons, in whom it is often the product of multiple conditions that produce the defining feature of uncertainty of position or motion in space. Identifying it as a geriatric syndrome should call attention to the multiplicity of factors that can conspire to produce the symptom, but it must never suggest that dizziness is just another undiagnosable, untreatable reason why old age ain't for sissies (15). The 17-minute managed-care visit will rarely suffice for evaluating the elderly patient with dizziness. This geriatric syndrome requiresand deservescareful attention to sort out the underlying diagnoses and most often to treat successfully.