Vestibular disorders are characterized by vertigo, disequilibrium, oscillopsia, and autonomic signs. These problems can contribute to reduced independence in activities of daily living and health-related quality of life (HRQoL).1–3 Most vestibular disorders are relatively benign, but they can still cause significant problems in the ability to function.1 Vestibular disorders are also burdensome to society as a drain on the economy,4 because of lost work hours, decreased participation in society outside the home, and increased health-care costs. Diagnostic testing, alone, does not provide information about the need for intervention. The patient's overall health, functional status, and personal goals are important in determining the need for care and the type of intervention.5
“Dizziness” and vertigo are among the most common complaints in medical practice, affecting approximately 20% to 30% of people in the general population.6 These symptoms are relatively more common in the older population. From the National Health Interview Survey, USA, among 37 million elderly persons, 7 million persons (19.6%) reported a problem with dizziness or balance in the preceding 12 months.7 On a German survey (n = 1003), dizziness/vertigo had a prevalence of 22.9% within the last 12 months and an incidence (first episode) of 3.1%. For vestibular vertigo, the prevalence was 4.8% and the incidence was 1.4%.8
Despite the statistics cited above, the significant impact of vestibular disorders on functional performance is still not widely recognized. For example, the International Society of Physical and Rehabilitation Medicine sponsored a workshop to identify the health conditions that are most associated with disability and are amenable to rehabilitation interventions.9 Participants, who were physicians and other health-care providers who specialize in rehabilitation, were generally unaware of vestibular disorders. In total, participants identified 103 rehabilitation-relevant health conditions, some of which were related to vestibular diseases, such as hearing loss and falls. Participants failed to identify disorders of vestibular function or other diseases of the inner ear as significant and treatable problems. This chapter will elucidate the concept of disability, the interface between disability and vestibular disorders, and the assessment tools used to evaluate functional status.
Confusion in disability terminology impairs communication among investigators, clinicians, and patients.1 The National Institutes of Health (NIH) used the term “functional limitations” to refer to limitations in functioning in the immediate environment for basic self-care skills and other essential activities of daily living.10 The NIH used the term “disability” to describe how the individual interacts with the social environment, and used the term “societal limitations” to describe how barriers defined by laws or social policy restrict functional performance.
One of the first widely used models, the Nagi disability framework, used basic concepts of active pathology, impairment, functional limitation, and disability.11,12 In this framework, disability was defined as “limitation in performance of socially defined roles and ...