________________________________________________________________________ Dizziness and Vertigo
SYSTEMIC ETIOLOGIES Dizziness and vertigo are associated with systemic diseases or conditions as symptoms, comorbidities, risk factors, or shared pathophysiologic pathways. These most commonly involve hemodynamic (orthostatic hypotension), metabolic (diabetes), cigarette smoking, and cardiovascular origins. ORTHOSTATIC HYPOTENSION Orthostatic hypotension is typically defined by a sustained decline in blood pressure of at least 20 mm Hg systolic or 10 mm Hg diastolic within three minutes of standing, with symptoms of lightheadedness or presyncope on arising. Vertigo is a common and under-appreciated symptom [8]. Orthostatic hypotension is common in older people and a frequent complication of (excessive) hypertensive medica- tion. Such patients experience postural dizziness without documented syncope based on transient reductions in cerebral blood flow. Orthostatic hypotension may occur 5 to 30 minutes after remaining asymptomatic in the upright position, or when orthostatic vital signs have been normal. It may be missed as a cause of periodic syncope or presyncopal dizziness [15]. DIABETES Vestibular dysfunction is a complication of type 2 diabetes, with reported rates 70% higher compared with age-matched controls. Both central and peripheral vestibular dysfunction are observed in type 1 and type 2 diabetes. Hypertension medi- ates 42% of the association between type 2 diabetes and BPPV, suggesting that hypertension provides the mediating pathway for diabetes’ impact on the vestibular system [64]. CIGARETTE SMOKING In one study, the association between peripheral vestibular disorders and smoking was examined in patients (mean age: 65.3 years) treated for hypertension, dyslipidemia, or diabetes in primary care and followed over one year for new peripheral vestibular disorder events [65]. Compared with never-smokers, the risk of new-onset peripheral vestibular disorder was 2.22 times greater for ever-smokers and 2.70 for all ever-smokers with ≥30 pack-years. Compared with male never-smokers, the risk of new onset peripheral vestibular disorder was 4.41 greater for male ever-smokers with ≥30 pack-years. There were too few female heavy smokers to compare against female never-smokers [65].
VESTIBULAR IMPAIRMENT, ANXIETY, AND PERCEPTION Clinically relevant vestibular system interactions with traumatic stress, depressive disorders, and other psychiatric disorders have been described. However, vestibular-anxiety interactions are the most extensively studied and compelling and will be the focus of this section. Anxiety disorders account for 8% to 10% of cases with vestibu- lar symptoms as primary complaints [66]. In patients presenting with dizziness concerns, the rates of panic disorder are 5 to 15 times greater than the general population. Patients with panic disorder frequently experience significant dizziness and often demonstrate vestibular dysfunction [67]. The high co-occurrence of vertigo and anxiety has been described since antiquity [50]. By the late 1800s, dizziness and vertigo, anxiety, autonomic arousal, appraisal of spatial orientation, and threat assessment were appreciated as core contributors to agoraphobia; otologic disease was found to precipitate agoraphobia in patients with anxiety. As otology, neurology, and psychiatry matured into separate specialties in the early 20th century, agoraphobia became a psychiatric disorder and lost its spatial and motion context [62; 68]. While traditional medical teaching describes a narrow range of vestibular system functions (e.g., gaze stability, balance) and dysfunctions (e.g., dizziness, unsteadiness, vertigo), ves- tibular involvement in brain processes beyond balance, spatial orientation, and gait is established. The inter-relationship of anxiety and balance disorders is being rediscovered more than a century later [69; 70; 71]. Increasingly demonstrated is the extent of multi-directional connectivity and interaction between threat/anxiety, ves- tibular, visual, and somatosensory systems, and how this helps explain the shared pathophysiology, clinical features, and prevalent comorbidity [72]. As such, it is important to assess for, and treat when present, anxiety disorders, cognitive impairment, and perceptual disturbances in patients with diz- ziness/vertigo complaints [49; 69; 70]. The suggestion is made that dichotomous thinking (structural disease vs. “emotional issues”) should be discarded in order to effectively assess ves- tibular, psychiatric, and perceptual dysfunction. Each of these domains should be addressed simultaneously for favorable treatment outcomes [73].
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