________________________________________________________________________ Dizziness and Vertigo
Vertigo, dizziness, spatial disorientation, and disequilibrium can result from: asymmetrical vestibular inputs; vestibular hypofunction causing sensory mismatch in brain integration of sensory inputs; pathologies that affect any peripheral (e.g., inner ear, 8th cranial nerve) or central (e.g., vestibular nuclei and brainstem or cerebellar connections) vestibular system component; or a host of systemic, drug-effect, psychiatric, and physical trauma-related factors [14; 16; 17]. Around 80% of dizziness or vertigo cases are peripheral and 20% are central in origin [11]. EPIDEMIOLOGY Dizziness is a general, umbrella term that encompasses symptoms of impaired spatial perception. Vertigo is often consolidated into the umbrella term dizziness due to highly variable descriptions of the experience. Dizziness/vertigo is the second most common complaint in the ambulatory setting and constitutes 25% of neurology outpatient referrals, 13% of ED neurology consultations, and more than 3 million ED visits annually [9; 18]. The primary complaint of dizziness accounts for 5.6 million clinic visits annually in the United States. Vertigo is roughly two-thirds more common in women than men. Prevalence increases with age but varies depending on the etiology [19]. Benign paroxysmal positional vertigo (BPPV) is the most frequent vestibular disorder and the most common cause of peripheral vertigo, with a lifetime prevalence of 10% [20]. In the general population, the one-year prevalence rate is about 5% for vertigo, 1.6% for BPPV, and <1% for vestibular migraine [19]. An estimated 17% to 42% of vertigo cases are diagnosed as BPPV [21]. Peripheral causes of vertigo are usually, but not always, benign, while central vertigo often indicates a more serious pathology [11]. The negative impact of vertigo should not be underesti- mated; around 80% of patients report interruption in daily activities, including employment, from symptoms and the need for medical attention [19]. Dizziness, vertigo, and associated symptoms do not always fall easily into either a peripheral or central syndrome or disorder. Patients can have a dominant group of symptoms more closely tied to peripheral or central origin, while others will show a mix of both groups [22]. In the following discussion of pathophysiology, the diagnostic entities associated with dizziness or vertigo are mainly orga- nized by peripheral or central origin and by shared etiolo- gies or clinical features in a few instances. Throughout this course, “benign” is a pathologic and not a clinical descriptor; “benign” vestibular conditions can be intensely distressing for the patient.
PERIPHERAL CAUSES OF DIZZINESS AND VERTIGO BENIGN PAROXYSMAL POSITIONAL VERTIGO As indicated by the name, BPPV describes benign (not life- threatening or malignant) paroxysmal (comes in sudden, brief spells) positional (triggered by certain head positions or move- ments) vertigo [23]. It is characterized by rotational vertigo induced by head position changes, especially when extending or turning the neck, lying down, or rolling over in bed [20]. Epidemiology As noted, BPPV is the most frequent vestibular disorder and the most common cause of peripheral vertigo, with a lifetime prevalence of 10% [20]. Women are more often affected than men, with a female-to-male ratio of 1.5–2.2 to 1 [21; 24; 25]. The most frequent age of onset is between the fifth and sev- enth decades of life. BPPV has an overall prevalence of 3.4% in persons older than 60 years of age and is present in 40% of geriatric patients seen for dizziness [26]. The incidence increases with age due to age-related degeneration of the oto- lithic membrane [9]. The adverse impact on health and qual- ity of life is more severe in older individuals, and BPPV is an important health concern in the elderly because it contributes to falls and associated morbidity and mortality [15; 21]. With a 27% to 50% rate of spontaneous resolution, BPPV can be self-limiting or may persist to become a chronic recurrent disorder [15; 21]. An estimated 85% of patients experience interrupted daily activities/lost days at work, 68% reduce their workload, 4% change their job, and 6% quit their job from the disruptive impact of BPPV [27]. The direct and indirect costs of BPPV are significant. Delayed diagnosis and treatment is frequent. It costs an average $2,000 to arrive at the correct diagnosis, and costs related to BPPV diagnosis alone approach $2 billion annually [21]. Only 10% to 20% of patients with BPPV seen by a physician receive recommended repositioning therapy. Before specialist referral, more than 65% of patients receive potentially unnec- essary diagnostic testing or treatment, including magnetic resonance imaging (MRI) (70%), computed tomography (CT) (45%), electrocardiogram (41%), and medication therapy (53%). Delayed diagnosis and treatment of BPPV has cost and quality-of-life implications for patients and their caregiv- ers [21; 27]. Across disciplines, the practice variations in BPPV manage- ment are considerable, and medication treatment of BPPV varies substantially among primary care providers and across specialties [21].
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