Comparing caloric and self-experienced dizziness symptoms: diagnostic value and implications in functional dizziness.

Background: The diagnostic value of dizziness symptom quality is limited by variability in patient self-reports. Comparing it to the experience during standardized caloric stimulation could help control for individual differences in dizziness experience and reporting. As a nonphysiological stimulus, caloric testing may serve as a proxy for acute peripheral vestibular disorder. We hypothesized that dizziness of peripheral origin would be perceived as more similar to caloric stimulation than nonperipheral dizziness.

Methods: Patients with peripheral (n = 49) and nonperipheral dizziness (n = 34) were compared. Using newly developed questionnaires, participants rated the intensity of 30 symptoms during both dizziness and caloric stimulation, compared symptom intensity between the two, and rated overall similarity.

Results: Peripheral patients did not perceive caloric stimulation as more similar to their symptoms than nonperipheral patients. This also held for the functional dizziness subgroup (n = 14). However, exploratory analyses suggest symptom-specific group differences based on the directional intensity difference. For example, peripheral patients reported stronger spinning during their dizziness, whereas nonperipheral patients reported stronger spinning during caloric stimulation. These group differences outperformed those based on the dizziness ratings alone, which likely reflects pronounced caloric symptoms in the nonperipheral group, especially in functional dizziness, rather than stable individual differences. Peripheral patients also reported stronger caloric symptoms than controls without dizziness (n = 20). Symptom-specific group differences were not accounted for by slow-phase velocity of caloric nystagmus.

Conclusions: This study highlights the potential diagnostic value of comparing symptoms with caloric stimulation and provides further support for motion perception overestimation in functional dizziness.