Definition
Dizziness is a broad term used to describe various abnormal sensations arising from perceptions of the body’s relationship to space or of unsteadiness. Dizziness has been arbitrarily defined on the basis of duration as acute (present for less than 1 or 2 months) or chronic (present for more than 1 or 2 months). The differential diagnosis of acute dizziness is similar in younger and older persons and management of acute dizziness is not qualitatively different in older persons as compared to younger adults, with the possible exception that recovery maybe more prolonged in older adults. This chapter focuses on chronic dizziness.
Epidemiology
The prevalence of dizziness ranges from 4% to 30% in persons aged 65 years or older, and more commonly is reported by women than men. In one study of persons aged 65 years and older, the likelihood of reporting dizziness increased by 10% for every 5 years of increasing age.
Chronic dizziness is associated with a number of comorbid conditions, including falls, functional disability, orthostatic hypotension, syncope, and strokes. In older persons, chronic dizziness can cause significant adverse effects on a person’s quality of life. In one prospective study of older persons with dizziness, after 2 years of follow-up, older persons with dizziness were more likely to become disabled than were those who were not, although mortality was no different. In another study, 197 older persons with chronic dizziness reported poor health-related quality of life, most notably in relation to limitations in the physical and emotional dimensions. Chronic dizziness is also associated with fear of falling, worsening depressive symptoms and self-rated health, and decreased participation in social activities.
Pathophysiology
Dizziness is a sensation of postural instability or imbalance. Dizziness can be difficult to diagnose, specifically in older persons, in whom it often represents dysfunction in more than one body system. Maintenance of balance and equilibrium is complex, achieved by integration of sensory information obtained from vestibular, proprioceptive, visual, and auditory systems by the cerebral cortex and cerebellum, leading to appropriate balance-maintaining responses. Abnormal function in any one or a combination of these systems may result in imbalance and the sensation of dizziness.
The vestibular system maintains spatial orientation at rest and during acceleration. Elements of the vestibular system and its connecting pathways include the semicircular canals, utricle, saccule, vestibular nerve, vestibular nuclei, vestibulospinal tracts, and vestibulocerebellar pathways. Diseases affecting this system and producing dizziness include Ménière’s disease, benign paroxysmal positional vertigo (BPPV), recurrent vestibulopathy, labyrinthitis/vestibular neuronitis, acoustic neuroma, and drug toxicity (especially aminoglycosides). Age-related changes have also been reported in the sensory (hair) cells in the semicircular canals, saccule, and utricle.
The proprioceptive system consists of mechanoreceptors in the joints, peripheral nerves, and posterior columns, and multiple central nervous system (CNS) connections. Proprioception contributes to equilibrium by providing information about changes in body position, and helping mediate the body’s response to position change. Common disorders include peripheral neuropathy associated with diseases such as diabetes or vitamin B-12 deficiency and cervical degenerative disorders. The few data on age-related changes in proprioception have been conflicting with one study reporting a substantial decline in joint position sense with aging, while another found no major changes.
Vision provides important information about spatial orientation, and is relied upon particularly when vestibular and/or proprioceptive function is impaired. Common ocular diseases include cataracts, macular degeneration, and glaucoma. Age-related visual changes include decrease in each of visual acuity, dark adaptation, contrast sensitivity, and accommodation (see Chapter 43). Hearing also provides spatial clues, but to a lesser extent than vision. Impairment in hearing, common in older persons, maybe secondary to age-related changes or to disease processes (see Chapter 44).
The cerebral cortex and cerebellum, along with their synaptic networks, integrate information and supply the musculoskeletal system with information for appropriate responses. Because of multiple and complex connections, essentially any CNS disorder can lead to imbalance, which may manifest as dizziness.
Presentation
Dizziness is described using many names, including vertigo, lightheadedness, dysequilibrium, giddiness, wooziness, and spinning. The sensation of dizziness is commonly categorized as vertigo, dysequilibrium, presyncope, and other. In addition to these four types, another category, mixed dizziness, is a combination of two or more of the above types. Mixed dizziness is the most common type of dizziness reported by older persons.
Vertigo refers to a sensation of spinning, in which the individual perceives movements of the environment in relation to the body (objective vertigo) or vice versa (subjective vertigo). Vertigo is often assumed to result from disorders of the vestibular system and its connecting pathways although other causes of dizziness such as cervical disorders may present as vertigo as well.
Dysequilibrium refers to feelings of unsteadiness or imbalance primarily involving the lower extremities or trunk rather than the head. The person often expresses the feeling that they are about to fall. Dysequilibrium results mostly from disorders of the proprioceptive system, musculoskeletal weakness, or cerebellar disease.
Presyncope is a feeling of lightheadedness or impending faintness or the sensation that one is about to pass out. Presyncope usually results from hypoperfusion of the brain; cardiovascular causes (including vasovagal disorders) are common causes in older persons.
Often the sensation does not fit any of the above three types. The patient may describe “whirling,” “tilting,” “floating,” and other nonspecific sensations. Furthermore, the correlation between sensations and organ systems is not as consistent among older persons as younger persons. Thus, the sensation reported does not have diagnostic specificity in older patients.
In addition, although dizziness maybe a symptom of one or more discrete diseases, multifactorial etiologies of dizziness are common in older persons. Chronic dizziness is associated with risk factors such as angina, myocardial infarction, arthritis, diabetes, stroke, syncope, anxiety, depressive symptoms, impaired hearing, and polypharmacy. In a population-based study of community-dwelling older persons, the factors that were independently associated with dizziness included anxiety, depressive symptoms, impaired hearing, the use of five or more medications, postural hypotension, impaired balance, and a past history of myocardial infarction. Almost 70% of patients with five or more of the above risk factors reported dizziness, whereas only 10% of patients with none of these factors reported dizziness. These findings suggest that chronic dizziness, at least in a subset of older persons, maybe a geriatric syndrome that is the result of the accumulated effect of multiple coexisting risk factors and diseases.
As presented in the following section, dizziness maybe the presenting complaint of a discrete disease or the results of contributing multiple factors.
Etiology
Vestibular diseases have been reported in anywhere from 4% to 71% of older persons with dizziness. The most common vestibular disorders causing chronic dizziness in older persons are Ménière’s disease, BPPV, recurrent vestibulopathy, the effects of ototoxic medications, and acoustic neuroma.
Ménière’s disease, also called endolymphatic hydrops, is reported in 2% to 8% of older patients with dizziness. It is a debilitating disorder of the inner ear, consisting of a triad of recurrent episodic vertigo, tinnitus, and fluctuating sensorineural hearing loss. A sensation of fullness in the inner ear is common. Episodes of true vertigo usually last for 1 to 24 hours. The patient may complain of nausea, vomiting, and headaches during the episodes. The exact cause is unknown, but the pathology is characterized by excess endolymph within the cochlea and vestibular labyrinth. The disease is unilateral in a majority of patients; men and women are affected equally. In a 14-year follow-up study, the episodes of vertigo disappeared in 50% of patients and improved in 28%, while hearing in the affected side was absent in 48% and impaired in 21% of the patients.
BPPV has been reported to be the cause of dizziness in 4% to 34% of cases. In this condition, patients report sudden-onset, episodic vertigo, often associated with nausea and/or vomiting, precipitated by changes in the position of the head, such as rolling over in bed, getting in and out of bed, or bending forward to pick something up. It is classically accompanied by rotational nystagmus. In most cases, the etiology is unknown, although some patients have a history of head injury or viral neurolabyrinthitis. BPPV results from freely moving particulate matter within the posterior semicircular canal. These particles most likely are dislodged otoconia, which are tiny calciferous granules that make up part of the receptor mechanism in the otolithic apparatus. It is postulated that movement of these free-floating particles cause alteration in the endolymphatic pressure, resulting in episodes of vertigo and nystagmus. In one study, researchers reported that otoconia undergo degenerative changes, which may lead to their dislodgment from the utriculus. A definitive diagnosis of BPPV can be made by the Dix–Hallpike test described under “Evaluation” later in this chapter.
Recurrent vestibulopathy is an idiopathic disorder characterized by recurrent episodes of vertigo without auditory or neurological symptoms or signs. The vertigo usually lasts from 5 minutes to 24 hours. It is differentiated from Ménière’s disease by the absence of auditory symptoms. Over 8.5 years of follow-up, spontaneous recovery was reported in 62% of patients. The diagnosis was changed to Ménière’s disease or benign positional vertigo in 14% and 8% of patients, respectively.
Acoustic neuroma, also known as cerebellopontine angle tumor, is a benign tumor of the eighth cranial nerve, and is reported in 1% to 3% of older persons with dizziness. Clinical features include tinnitus and progressive unilateral sensorineural hearing loss, particularly for the higher frequencies. Patients complain more often of a feeling of unsteadiness rather than of true vertigo. Patients with large tumors may also complain of occipital headache, diplopia, paresthesias in trigeminal or facial nerve distribution, and/or ataxic gait.
The frequency of cerebrovascular disease ranges from 4% to 70% among older persons with dizziness. Patients with transient ischemic attack (TIA) or stroke involving vertebrobasilar distribution commonly present with dizziness, along with diplopia, or dysarthria, numbness, or weakness. Dizziness rarely is a presenting symptom in patients with anterior or posterior cerebral artery ischemia or with internal carotid artery disease. The patient may complain of either a rotatory or nonrotatory dizziness along with other neurologic symptoms and signs. A number of specific stroke syndromes present with dizziness, including cerebellar infarction and posterior lateral medullary artery infarction, also known as Wallenberg’s syndrome.
Other central nervous disorder causes of dizziness include Parkinson’s disease and basilar artery migraine. The latter is rare in older persons.
Anxiety, depression, obsessive-compulsive disorder, panic disorder, and other psychiatric conditions are among the most common causes of chronic dizziness in young adults. In older persons as well, psychiatric conditions are often associated with dizziness. Common psychiatric conditions causing or contributing to dizziness in older persons include depressive and anxiety disorders. Recent studies show that depressive symptoms are associated with symptoms of dizziness, while, conversely, persons who have chronic dizziness are at increased risk of depression, suggesting a reciprocal relationship between dizziness and depressive symptoms among older persons.
Disorders of the cervical spine as a cause of dizziness in older persons have been reported in the range of 0% to 57%. Patients with cervical dizziness usually present with vague lightheadedness or vertigo associated with turning of the head. Both vascular and proprioceptive mechanisms have been proposed to explain cervical dizziness.
Obstruction of the vertebral arteries is thought to be the most common vascular mechanism of cervical dizziness. One hypothesis suggests that in the presence of atheromatous narrowing of one vertebral artery, rotation of the head may cause sufficient obstruction of the contralateral vertebral artery to produce ischemia of the brainstem. Another hypothesis suggests that turning the head or neck results in compression of adjacent vertebral artery by a strategic osteoarthritic spur, causing a transient disruption of the blood flow.
Degenerative changes in the cervical spine may cause dizziness because of impairment of the cervical proprioceptive mechanoreceptors. These receptors provide information for postural control via the vestibulospinal tract. The patient may present with decreased range of motion and radicular pain in the neck upon movement, as well as dizziness.
Hypothyroidism, anemia, electrolyte imbalance, hypertension, coronary artery disease, congestive heart failure, and diabetes mellitus are commonly found in patients with dizziness, although the frequency of dizziness as a symptom of each is low. Studies have found an independent association between dizziness and a history of hypertension, angina, myocardial infarction, and diabetes mellitus. Systemic disorders may contribute to instability or dizziness by affecting the sensory, central, or effector components. These systemic disorders may also cause decreased cerebral perfusion or oxygen delivery, fatigue, or confusion, each of which may subsequently lead to a sensation of instability or dizziness. Chapter 57 discusses cardiovascular disorders that can cause dizziness as well as syncope.
Orthostatic hypotension is a primary or contributing cause in 2% to 15% of older persons with dizziness. There is a long list of causes of orthostatic hypotension (see Chapter 57). Although there is no consensus on the definition of orthostatic hypotension in older adults, commonly noted criteria include a 20 mm Hg drop in systolic blood pressure, a 10 mm Hg drop in diastolic blood pressure, or typical symptoms associated with any drop in blood pressure after standing from a supine or sitting position. Another entity reported in literature is postural dizziness, in which patients complain of dizziness on standing from a supine position but have no drop in blood pressure. In these studies, a subset of patients who have orthostatic blood pressure changes do not complain of dizziness, suggesting that orthostatic changes in blood pressure maybe asymptomatic, while, conversely, all dizziness with postural changes may not be caused by a drop in blood pressure. Vestibular dysfunction is thought to account for the postural dizziness not accompanied by postural blood pressure drops.
Another important entity to consider in older persons is postprandial hypotension. Postprandial hypotension is defined as a decrease in systolic blood pressure of 20 mm Hg or more in a sitting or standing posture within 1 to 2 hours of eating a meal; dizziness often is a symptom. In a recent study, the effects of postprandial hypotension and orthostatic hypotension were found to be additive but not synergistic, suggesting that the two entities have different pathophysiological mechanisms. Possible etiologies of postprandial hypotension are discussed in Chapter 57.
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