Timothy C. Hain,
Last edited: 7/2002. Please read our disclaimer.
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Dizziness is a common symptom, potentially deriving from many categories of illness, and our diagnostic acumen and technology is not perfect. It is not unusual to conclude that one simply doesn't know why a person is dizzy, even after a very thorough evaluation.
Unlocalized dizziness is not the same as "undiagnosed" or "psychogenic". Unlocalized literally means that dizziness cannot be attributed to an anatomic lesion in a specific place. Undiagnosed vertigo means that the cause of the vertigo is presently unknown. Psychogenic vertigo means that the vertigo is caused by a psychological disturabance.
Anxiety and panic disorder are the most common sources of psychogenic dizziness.
Panic disorder is characterized by a sudden inexplicable feeling of terror. According to the DSM manual, the criteria for the research diagnosis of Panic is a sudden onset of fear that peaks in approximately 10 seconds, accompanied by at least four of the following symptoms:
These symptoms are common and of course, could be due to other sources. The incidence of panic is high -- about 1/75 persons worldwide. It can be inherited or acquired. (Shipko, 2002). Many persons with panic also have vestibular disorders. Psychogenic dizziness is commonly situational and responsive to benzodiazepine medications. SSRI medications are also used in this situation. Both benzodiazepines and SSRI medications may worsen objectively measured balance.
Depression is an extremely unusual cause of vertigo but can be a source of ataxia, aural fullness and hypersensitivity to somatic input resulting in tinnitus.
Confusion between psychogenic and undiagnosed vertigo. A large number of patients have dizziness associated with or attributed to psychiatric etiologies. Some authors indicate that as many as 50% of all dizzy patients have a "functional" source of complaints. However, this large percentage results from an algorithm where patients with no findings on testing were assigned this diagnosis. This process is obviously fraught with peril, given that it lumps together patients where the diagnostic process may have failed with those who do indeed have a psychological origin of symptoms. In the author's practice, only about five percent of patients are assigned the "psychogenic" diagnosis, but there are considerable greater numbers in whom secondary anxiety is inferred.
Malingering: Because dizziness and associated hearing complaints such as tinnitus are largely subjective, malingering is possible. Malingering is characterized by lack of physical findings or test abnormalities a secondary gain factor. Common situations are whiplash injuries or individuals involved with the workman's compensation system. School age children also can present with symptoms apparently created in an effort to avoid going to their classes. Somatization disorder is similar to malingering in clinical appearance but it lacks a secondary gain motivation. Functional elaboration of organic symptoms are also common -- for example, detection of elaboration of symptoms associated with gentamicin toxicity can present an extremely difficult clinical challenge. When these disorders are suspected, it usually best to refer the patient to an experienced clinician, as there are specialized tests for psychogenic hearing and balance disorders that are often helpful, and because of the high frequency of litigation in these situations.
Diagnosis: Sorting out diagnoses in dizzy patients is intrinsicially difficult, and parsing out individuals who may be somewhat uncooperative is sometimes impossible. A prototype patient with psychogenic dizziness is middle aged, has vague and elusive symptoms, and has no physical findings or objective test abnormalities. The clinician may be helped by results of neuropsychological testing, specialized analysis of vestibular tests. There are a few inventories that are aimed at detecting psychopathology, for example the "Basic Symptom Inventory 53", proposed by Ruckenstein and Staab (2001).
In elderly patients, it is unusual for the physician to say that he does not know what is causing dizziness. Instead, dizziness and/or ataxia without localizing signs are often designated as "disequilibrium of the elderly", and attributed to the ravages of age. For example, in a series of 740 patients with dizziness, Belal and Glorig (1986) reported that 79% were given the diagnosis of "presbyastasis," a term synonymous with disequilibrium of aging. According to the authors, this diagnosis was assigned to persons above the age of 65 in whom no specific cause of dizziness was identified. In one study, 116 elderly patients presenting to a neurotology setting were examined. In spite of an unusually thorough assessment, roughly 35% of patients were diagnosed as "Undetermined", "psychophysiologic", and "vestibulopathy, undetermined" or in other words, remained unlocalized (Baloh et al, 1989).
Gait disorders should be considered seriously in the elderly. A recent study showed that the severity of gait disorder and its rate of progression is strongly associated with risk of death (Wilson et al, 2002).
Whether dizziness in elderly persons without a localizable lesion should attributed to aging, per se, is a difficult problem to sort out because most elderly do show some measurable sensory or central nervous system differences from younger people. The vestibular system of older people shows a gradual attrition of neural and sensory cells including reduction in hair cell and nerve fiber numbers. (Engstrom et al, 1974; Lopez et al, 1997). Centrally, cerebellar Purkinje cells gradually reduce over life (Hall et al, 1975). Neuronal and fiber loss also occurs in the extrapyramidal system, the part of the brain that is responsible for movement disorders. Vision and position sense also under gradual deteriorations with age. Reaction time is reduced with age. Considering the numerous processes that deteriorate with time, there are an abundance of possible causes of age-related ataxia.
One potential source of error is to attribute ataxia or dizziness to lesions which are not causally connected. For example, there are many patients with small strokes, sensory dysfunction, cataracts, etc, which by themselves would not be enough to cause ataxia, but which, possibly in combination, may be responsible for ataxia in the extreme elderly. Still, how do we know that an arbitrary combination of sensory, central, and motor deficits is an adequate explanation for ataxia?
Another potential source of error is our inability to quantify vestibular dysfunction which leads to dizziness. For example, at present, we have no clinical tests that can identify lesions of the vertical semicircular canals or otoliths. In the elderly, there is a special problem because of our unwillingness to subject elderly patients to extensive diagnostic evaluations. For example, as mentioned previously, Fife and Baloh (1993) pointed out the high prevalence of bilateral vestibulopathy in elderly patients who had disequilibrium or dizziness of uncertain cause. Older people may also have impairments in their initial vestibular reflexs (Tian et al, 2001). Others have suggested that the elderly have more cerebellar vascular disorders (Norrving et al, 1995), as well as more BPPV.MRI studies of older persons with disequilibrium and gait disturbances of unknown cause often shows frontal atrophy, and subcortical white matter T2 hyperintense foci. (Kerber et al, 1998). Pathological studies, though scanty, suggest frontal atrophy, ventriculomegaly, reactive astrocytes in the frontal periventricular white matter, and increased arteriolar wall thickness (Whitman et al, 1999).
Ones approach to the management of dizziness of unlocalized cause should be cautious and empirical. These patients usually need to be followed more closely than patients in whom a clear diagnosis is available. Empirical trials of medication, psychiatric consultation, and physical therapy may be helpful.In the author's practice, patients with undiagnosed dizziness are generally treated both with medications as well as a 1 or 2 month enrollment in a balance/vestibular rehabilitation program, for patients who have chronic symptoms. Recent studies have suggested that vestibular rehabilitation reduces severity of agoraphobia in persons with agoraphobia and vestibular dysfunction (Jacob et al, 2001) . Interventions may include gaze-stabilization, gait training, strenghtening, and "general" procedures.