Dizziness and Vertigo _________________________________________________________________________
SHARED CLINICAL FEATURES Patients with vestibular or balance disorders often have anxiety symptoms. Likewise, patients with anxiety disorders often show vestibulo-ocular and/or peripheral vestibular dysfunction [74]. Vestibular and balance abnormalities are especially common in panic disorder with agoraphobia [71]. Chronic anxiety and anxiety disorders may be causes or compli- cations of vestibular symptoms or disorders. These psychiatric disorders affect 30% to 50% of patients who seek specialist care for vestibular symptoms, and they adversely affect the treat- ment outcomes of patients with vestibular disease, especially when unrecognized [62; 72]. Vestibular function is linked to emotional states through complex bidirectional interactions; vertigo worsens emotional symptoms, and emotional states can amplify perceptions of vertigo or disequilibrium [70].
The brain normally resolves mismatched sensory information by updating and realigning the internal spatial representation of the body with the surrounding space. Impairment of one sensory signal is compensated by reweighting of intact sensory inputs [62; 78]. Unsuccessful reweighting impairs multisensory integration, leading to incongruity between visual and vestibu- lar information and visual-vestibular sensory mismatch. This can elicit an erroneous cortical representation of the body within the surrounding space, producing spatial disorienta- tion, anxiety, dizziness, balance problems, and increased risk of falls [62; 78; 79; 80]. Visual Dependence Visual dependence is an over-reliance on visual information to maintain spatial orientation, which compensates for vestibular dysfunction that impairs multisensory integration. Space- motion discomfort, a prominent feature resulting from the visual-vestibular conflict, may cause symptoms of imbalance, discomfort, anxiety, or phobic avoidance in situations where moving, complex, or conflicting visual environments trigger intense dizziness/vertigo symptoms [71; 80]. Depersonalization and Derealization Depersonalization and derealization are perceptual abnormali- ties, described primarily from the psychiatric perspective for more than a century. Depersonalization (feeling detached, numb from one’s emotions, experiences), derealization (objects, people, and surroundings experienced as unreal, dis- tant, artificial, lifeless), and intact reality testing are symptoms of depersonalization/derealization disorder in the fifth revised edition of the Diagnostic and Statistical Manual of Mental Disor- ders (DSM-5-TR) [81; 82]. The DSM-5-TR also lists derealization and depersonalization as potential panic attack symptoms in the diagnostic criteria for panic disorder [82]. Trauma history and anxiety disorders are prevalent co-factors and antecedents of depersonalization/derealization. Phencyclidine or cannabis use can trigger acute symptoms [83]. Derealization symptoms are particularly distressing, if not profoundly intoler- able; an anxious or panic response can amplify depersonaliza- tion/derealization symptoms, creating a vicious cycle [81]. Patients diagnosed with depersonalization/derealization disorder have high rates of past-year inpatient hospitalization (25.6%) and ongoing outpatient psychotherapy (40.4%). Depersonalization/derealization disorder has been described as highly chronic, severely underdiagnosed, and often refractory to pharmacotherapy and psychotherapy [84].
ANXIETY, BALANCE, AND VESTIBULAR INTERACTIONS
Anxiety can impair ocular motor reflexes and gaze control, which may contribute to visual and visual-vestibular syn- dromes. Anxious states can amplify a normative gaze bias toward potentially threatening stimuli in the visual field, which, in patients with social anxiety disorder, may drive hypervigi- lance-avoidance gaze patterns. The impairing effect of anxiety on gaze control reduces gaze stability on visual targets, which may underlie dizziness and visual symptoms in PPPD [74; 75]. Exposure to heights reflexively increases body sway in normal subjects by reducing visual feedback to body sway (in the absence of motion). Body sway is more pronounced in subjects with height phobia, and anxiety-related gaze diversion may increase gait instability in patients with fear of falling [75; 76]. Space-motion discomfort describes symptoms of uneasiness over spatial orientation and hyperawareness of motion stimuli. In affected individuals, space-motion discomfort is triggered by movement in visually rich environments and exposure to moving or patterned objects while stationary. It is especially prevalent in patients with panic disorder and agoraphobia; persons with panic symptoms often become destabilized under conflicting sensory conditions. Visual vertigo and other situa- tion-specific interactions between balance and anxiety may be part of a broader space-motion discomfort profile [62; 74; 77]. DISRUPTED MULTISENSORY INTEGRATION The vestibular system maintains equilibrium through ves- tibular spinal reflexes, stabilizes visualization through the vestibular-ocular reflex, and contributes to spatial orientation [78]. Accurate perception of gravity and maintenance of spa- tial orientation, balance, and gait rely on brain integration of visual, vestibular, proprioceptive, and somatosensory signals and cognitive processes [79].
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