Abstract
Dizziness and imbalance are common conditions affecting people of all ages, particularly the elderly. In this chapter, we start by defining dizziness, imbalance, and presbyvestibulopathy , or age-related vestibular loss, which is of particular interest to the otolaryngologist, the neurologist, and the primary care physician. We then review the epidemiology of dizziness, imbalance, and presbyvestibulopathy. Finally, we discuss the impacts of these conditions on population health from the perspective of the older adult and the healthcare system.
Keywords
Aging, Disequilibrium, Dizziness, Epidemiology, Falls, Presbyvestibulopathy, Vestibular
Dizziness and imbalance are common conditions affecting people of all ages, and particularly the elderly. This chapter begins by defining dizziness, imbalance, and presbyvestibulopathy , or age-related vestibular loss, which is of particular interest to the otolaryngologist, the neurologist, and the primary care physician. Then the epidemiology of dizziness, imbalance, and presbyvestibulopathy will be reviewed. Finally, the impacts of these conditions on population health from the perspective of the older adult and the healthcare system will be discussed.
Definitions of Dizziness, Imbalance, and Presbyvestibulopathy
Dizziness connotes a subjective perception of disorientation or involuntary motion, which can occur during movement or at rest. Dizziness can be further characterized as vertigo and/or lightheadedness. Vertigo is the false sensation that either the body or the environment is moving (usually spinning) and may be a symptom of vestibular, visual, or neurologic impairment; psychological factors; or the use of multiple medications (“polypharmacy,” see Chapter 18 ). Lightheadedness is the sensation of impending loss of consciousness associated with transient diffuse cerebral hypoperfusion. Causal factors for lightheadedness typically include cardiovascular disease (e.g., aortic stenosis) and orthostatic hypotension (e.g., resulting from excessive medication use or autonomic instability).
Imbalance connotes disequilibrium or postural instability. Imbalance is usually described either while standing or walking and typically does not occur at rest. Imbalance can result from muscle weakness, arthritis, and/or reduced sensory input (e.g., visual, vestibular, proprioceptive) leading to impaired postural reflexes.
Presbyvestibulopathy refers specifically to aging of the vestibular system, akin to presbycusis (age-related hearing loss) and presbyopia (age-related vision loss). Numerous lines of evidence demonstrate a progressive decline in vestibular function associated with aging. Histopathologic studies have shown that hair cell populations throughout the vestibular apparatus (including the three semicircular canals and two otolith organs, the saccule and utricle) decline with age. Moreover, declining cell counts have also been observed for vestibular ganglion cells, primary afferents, and vestibular nucleus cell populations. Studies that have assessed vestibular physiologic responses have also observed declining semicircular canal and otolith responses associated with age.
Presbyvestibulopathy can contribute to symptoms of dizziness and/or imbalance in older individuals. The vestibular system plays an integral role in maintaining the vestibulo-ocular (VOR) and vestibulospinal reflexes (VSR). The VOR is important for stabilizing gaze during head movement, and VOR impairment manifests as dizziness (i.e., abnormal sensation of motion). The VSR is important for trunk and limb stabilization during head movement. VSR dysfunction manifests as imbalance or postural instability. Interestingly, there is increasing recognition of the physiologic importance of vestibulo-autonomic projections (see Chapter 15 ). Vestibulo-autonomic impairment has been associated with orthostatic hypotension. Thus presbyvestibulopathy may also be a causal factor for the symptom of lightheadedness. An effort is ongoing to establish formal diagnostic criteria for presbyvestibulopathy within the International Classification of Vestibular Disorders, a component of the International Classification of Diseases.
The relationship between dizziness, imbalance, and presbyvestibulopathy is depicted in Fig. 1.1 as a set of overlapping conditions. Emerging evidence suggests that a certain amount of presbyvestibulopathy is present in older individuals but may not manifest symptomatically as dizziness or imbalance. This may be because the level of vestibular impairment has not crossed a critical threshold, or because an individual is able to compensate for the presbyvestibulopathy. Presbyvestibulopathy is thus depicted in Fig. 1.1 as asymptomatic or “subclinical” and symptomatic or “clinical.” Moreover, it is evident in Fig. 1.1 that multiple factors in addition to reduced vestibular function have been associated with dizziness and imbalance in the geriatric population. It is well known among researchers who study aging that geriatric conditions often result from numerous factors that coexist at the same time and that may interact to have nonlinear, synergistic effects. Indeed, Tinetti and colleagues have described dizziness as a “geriatric syndrome,” whereby symptoms result not from sole disease entities but from accumulated impairment in multiple systems. As such, presbyvestibulopathy is often not the only contributor to dizziness and imbalance in older adults.
Epidemiology of Dizziness, Imbalance, and Presbyvestibulopathy
Prevalence
Estimates of the prevalence of dizziness and imbalance in the geriatric population depend largely on the definitions of dizziness and imbalance used and on the populations surveyed. The populations surveyed can vary with respect to their age ranges, whether they are population-based or clinic-based, and what types of clinics are being studied (e.g., primary care vs. specialty). Several large population-based studies report a 20%–30% prevalence of dizziness and imbalance in the elderly population (age ≥ 65 years). The prevalence of dizziness and imbalance is found to increase steeply with age, with levels over 50% in the community-dwelling population over age 80 years. A study in nursing home residents observes a prevalence of dizziness and vertigo of 68%. Among patients aged ≥65 years presenting to a geriatric primary care clinic, 24% report dizziness and 17% identify dizziness as their major presenting complaint. Within the otolaryngology clinic, one study of 131,000 consecutive patients found that 6% of patients over age 65 years presented with vertigo or a presumed vestibular diagnosis. Interestingly, this large-scale survey of otolaryngology practices found that visits from geriatric patients increased from 14.3% in 2004 to 17.9% in 2010. Moreover, this study noted that the five most common geriatric diagnoses were otologic, including hearing loss, external ear disorders, tinnitus, otitis media/Eustachian tube disorders, and vertigo.
A landmark series of studies based in Germany estimated the population prevalence and incidence more specifically of vestibular vertigo, i.e., vertigo resulting from vestibular impairment. Community-dwelling individuals aged ≥18 years were queried in a national telephone survey regarding symptoms of dizziness and vertigo. Those who reported moderate symptoms were administered a detailed neurotologic interview, from which vestibular vertigo was diagnosed based on symptoms of rotational vertigo, positional vertigo, or recurrent dizziness with nausea and oscillopsia or imbalance. The neurotologic interview was found to have good validity based on a gold standard of neurotology clinic-based diagnoses in establishing a vestibular diagnosis. The lifetime prevalence, 1-year prevalence, and incidence of vestibular vertigo were observed to be 7.8%, 4.9% and 1.5%, respectively. The 1-year prevalence of vestibular vertigo increased with age to 7.2% in 60- to 69-year-olds and 8.8% in individuals over age 80 years. This study was among the first to estimate the population prevalence of presbyvestibulopathy.
A more recent study estimated the prevalence of vestibular impairment in the US population using an objective, rather than subjective (self-report based), test. Data were drawn from the 2001–04 National Health and Nutrition Examination Survey (NHANES). Vestibular function was assessed in NHANES using the modified Romberg test, whereby vestibular impairment was inferred from an inability to stand on a foam pad with eyes closed. About 35% of US adults aged 40 years and older had evidence of balance dysfunction based on this postural metric. The frequency of balance dysfunction increased significantly with age, such that 85% of individuals aged 80 years and above had evidence of balance dysfunction. These estimates are considerably higher than the prevalences of vestibular vertigo reported earlier from the German population. It is possible that the symptom of vestibular vertigo represents clinical presbyvestibulopathy, whereas vestibular impairment based on the modified Romberg test encompasses both clinical and subclinical presbyvestibulopathy.
Of the major vestibular diagnoses, benign paroxysmal positional vertigo (BPPV) is particularly common in older adults and bears special mention (see Chapter 9 ). Increased BPPV in the elderly may reflect age-related degeneration of the otoconial membrane, leading to abnormal seeding of otoconia in the endolymph. A study of the German population observed a prevalence of 3.4% in individuals over age 60 years and a cumulative lifetime incidence of almost 10% by age 80 years. BPPV accounted for 39% of cases of vertigo in older patients presenting to neurotology clinics. However, older patients do not always experience the classic presentation of BPPV, short episodes of rotatory vertigo associated with changes in head position. A study of 100 older patients presenting to general geriatric practices for chronic medical conditions found that 9% had unrecognized BPPV. Moreover, patients with BPPV had significantly increased fall risk. Another study found that older patients with BPPV were more likely to experience postural instability. This instability could be improved through canalith repositioning maneuvers.
Risk Factors
Epidemiologic analyses of dizziness, imbalance, and presbyvestibulopathy have also investigated risk factors for these conditions. Most studies have observed an increased prevalence of dizziness and imbalance in women. Vestibular vertigo was also more prevalent in women. However, the prevalence of vestibular impairment based on objective modified Romberg testing did not differ by gender. Findings from a review of the most frequently reported causes of dizziness in primary care practice are presented in Table 1.1 . The review reported that peripheral vestibular disease was the most common cause of dizziness, observed in 20%–50% of patients. Peripheral vestibular diseases included BPPV, labyrinthitis, and vestibular neuritis. Other common causes of dizziness were cardiovascular disease, systemic infection (leading to orthostatic hypotension), psychiatric disorders, metabolic disturbances, and use of multiple medications. A more recent epidemiologic survey of the elderly population in England found that dizziness was associated with abnormal heart rhythm, hearing loss, vision loss, and low grip strength, whereas imbalance was associated with diabetes, arthritis, low grip strength, and vision loss. With respect to vestibular vertigo, independent risk factors were depression, tinnitus, and cardiovascular risk factors, including hypertension and dyslipidemia. Finally, independent risk factors for vestibular impairment as measured by the modified Romberg test included low socioeconomic status and diabetes mellitus.
| Category | Percentage of Patients (%) | Examples |
|---|---|---|
| Peripheral vestibular disease | 20–50 | Benign paroxysmal positional vertigo, labyrinthitis, vestibular neuritis |
| Cardiovascular disease | 10–30 | Arrhythmia, congestive heart failure, vasovagal conditions (e.g., carotid sinus hypersensitivity) |
| Systemic infection | 10–20 | Systemic viral and bacterial infection |
| Psychiatric conditions | 5–15 | Depression, anxiety, hyperventilation |
| Metabolic disturbances | 5–10 | Hypoglycemia, hyperglycemia, electrolyte disturbances, thyrotoxicosis, anemia |
| Medications | 5–10 | Antihypertensives, psychotropic medications |
Impacts of Dizziness, Imbalance, and Presbyvestibulopathy
Dizziness, imbalance, and presbyvestibulopathy have an immense effect on diverse health and economic outcomes that affect the individual and society. In this section, the impact of these conditions on falls, quality of life, activities of daily living, and healthcare utilization are reviewed. Emerging links between presbyvestibulopathy and cognitive decline are also explored.
Falls
Falls are a common and disastrous outcome in older individuals. One in three adults over age 65 years falls each year. About 10% of falls result in hip fracture, and a fall increases the likelihood of nursing home placement 10-fold. Dizziness has been associated with a two- to threefold increased risk of falling. Specifically with respect to presbyvestibulopathy, the previously mentioned study from NHANES found that individuals with objective vestibular impairment who were also clinically symptomatic (i.e., reported dizziness) had a 12-fold increase in the odds of falling. In a small pilot study, older fallers were found to have significantly higher rates of peripheral vestibular dysfunction than older non-fallers. A prospective study reported that elderly patients with vestibular asymmetry were significantly more likely to experience an incident fall. Moreover, several studies have observed an association between vestibular asymmetry and fall-related hip and wrist fracture risk. One study estimated that ∼50,000 excess falls per year in older adults could be attributable to vestibular loss.
Quality of Life
Quality of life measures assess the general quality of life (e.g., the Medical Outcomes Study 36-Item Short Form Health Survey) as well as health-related quality of life (i.e., related to a specific health condition). Dizziness and vestibular vertigo have been associated with significantly poorer quality of life, in both the physical and mental domains. One population-based study in Sweden found that dizziness was one of the most influential symptoms affecting the general quality of life in older individuals. The most widely used measures of dizziness- and imbalance-related quality of life are the Dizziness Handicap Inventory (DHI), the Activities Balance Confidence scale, and the Falls Efficacy scale (which measures fear of falling). Two studies that administered the DHI in patients presenting with dizziness to a primary care clinic and a specialized dizziness clinic found that over 60% of patients reported moderate to severe handicap associated with their dizziness in both clinical contexts.
Activities of Daily Living
One measure of the social and economic impact of dizziness, imbalance, and presbyvestibulopathy is the impact on the ability to carry out activities of daily living. Individuals who lose their ability to carry out certain activities of daily living rely more on others and society for daily functioning and in severe cases require placement in a nursing home. In 2008 the US National Health Interview Survey (NHIS) administered a Balance Supplement, and these data were analyzed across several studies to provide numerous insights into the health impacts and economic consequences of dizziness and imbalance in older individuals in the United States. One study considered the impact of dizziness and imbalance in older individuals on the ability to engage in daily activities. This study found that, of the elderly US population who reported dizziness or imbalance (∼20% of individuals aged ≥65 years), 52% reported difficulty shopping, 47% reported difficulty driving, and 46% reported difficulty participating in social activities because of their symptoms. Another study using data from NHANES evaluated the impact of vestibular dysfunction (based on the modified Romberg test) on the ability to carry out activities of daily living. Interestingly, when vestibular impairment was considered (rather than the symptoms of dizziness and imbalance), the particular activities that were most affected were managing money, using a fork and knife during eating, and getting in and out of bed.
Healthcare Utilization
With respect to healthcare utilization and economic outcomes, the German population-based study found that vestibular vertigo was more likely than nonvestibular vertigo to be associated with a medical consultation, sick leave, interruption of daily activities, and avoidance of leaving the house. Data from the 2008 NHIS demonstrated that 50% of older individuals with dizziness and balance problems saw at least one medical provider, typically a general practitioner (86% of individuals), a neurologist (24%), or an otolaryngologist (17%). Nearly 35% of older adults with dizziness and balance problems saw three or more providers. About 57% of older individuals with these symptoms obtained an imaging study, and 15% were prescribed a medication, most commonly a diuretic, anxiolytic agent, or meclizine. The study pointed out that despite this high rate of healthcare utilization, >40% of older individuals still did not have a clear diagnosis for their dizziness or balance problem. A single provocative longitudinal study found that patients with disequilibrium at baseline were at a significantly increased risk only for incident cognitive decline compared with controls.
Presbyvestibulopathy and Cognitive Decline
Emerging evidence suggests that vestibular loss associated with presbyvestibulopathy affects not only physical function (e.g., postural/gait abnormality, falls) but also elements of cognitive function. Studies have long documented a link between vestibular loss and cognitive impairment, for instance, memory impairment with perilymph fistulae, and concentration difficulties associated with gentamicin ototoxicity. In 2005 a landmark study reported significant reductions in spatial cognitive skills (spatial memory and spatial navigation) in patients with neurofibromatosis type 2 (NF-2) who had undergone bilateral vestibular schwannoma resection relative to age-matched controls. These patients were also found to have significant reductions in their hippocampal volumes. The hippocampus is known to play a critical role in generating the brain’s cognitive map of space, and authors postulated that vestibular loss may have led to hippocampal atrophy and subsequent impairments in spatial cognition.
Cognitive function encompasses multiple domains, including language, attention, memory, executive function, and spatial skills. Evidence suggests that vestibular impairment is most strongly associated with reductions in spatial cognitive function, which follows from the vestibular system’s role in sensing head movement and orientation in space. Recent studies have further evaluated the link between vestibular loss and cognition in older adults with presbyvestibulopathy, a far more common condition than NF-2. One study used data from the Baltimore Longitudinal Study of Aging, a cohort of healthy aging adults that has been followed up continuously since 1958. In this study, older adults with reduced vestibular function were found to have significantly poorer spatial cognitive skills relative to older adults with normal vestibular function, although there were no differences in language, memory, attention, or executive function abilities. Similar findings were made using data from NHANES and the NHIS, lending support to the idea that presbyvestibulopathy may increase the risk of spatial cognitive decline in older adults.
A further line of investigation has explored the relationship between vestibular impairment and cognitive decline among individuals with cognitive impairment and dementia, including Alzheimer disease (AD). It has previously been hypothesized that vestibular loss may contribute to the onset of AD, in part owing to the major cholinergic projections that emanate from the vestibular system to the hippocampus, and that are specifically degraded in AD. Recent provocative evidence has shown that patients with AD have significantly poorer vestibular function relative to age-matched controls. AD is a heterogeneous condition, with some patients having greater memory deficits and others having greater spatial or motor deficits. Emerging data suggest that vestibular impairment may be particularly prevalent in patients with a spatial phenotype of AD. These links between presbyvestibulopathy, cognitive decline, and dementia and AD are an area of active, ongoing investigation, and the precise nature of these relationships remains to be further characterized. Patients with AD are twice as likely to fall relative to healthy older adults, and contribute disproportionately to the high rate of falls observed generally in older adults. One in three adults aged 85 years and older will develop AD and dementia, and given the aging population, AD ranks as one of the most significant public health concerns of our time. If vestibular impairment does contribute to the onset or manifestation of AD, this will be critical knowledge to gain.
Finally, dizziness has been associated with a nearly twofold increased risk of mortality relative to older adults without dizziness. This same study, which used NHIS data that were linked to National Death Index data, found that the 5-year mortality rate among individuals with dizziness and imbalance was 9%, which was comparable with the mortality rates observed among individuals with cardiovascular disease (10.5%), cancer (11.6%), and diabetes mellitus (9.8%).
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