Platforms, Thematic Posters, and Posters for CSM 2007: POSTERS
Purpose/Hypothesis: Although dizziness and imbalance are common impairments with peripheral vestibular dysfunction (P-VeD), the underlying mechanisms have not been clearly delineated, in part, due to limitations of vestibular function tests. Although otolith function tests (i.e. subjective visual vertical, SVV, and vestibular evoked myogenic potential, VEMP) have been developed, the impairments due to canal versus otolith dysfunction have not been clarified. This hinders the diagnostic process and the selection of appropriate intervention. The purpose of this study was to compare dizziness and postural control impairments between adults with canal versus otolith dysfunction. Number of Subjects: Thirteen adults (mean age 46 years; s.d. = 6) diagnosed with uncompensated, chronic P-VeD were recruited. Exclusion criteria were any other orthopedic or neurological pathology. Materials/Methods: Subjects were grouped based on vestibular test Results: Group 1 – canal dysfunction only per bithermal caloric and/or rotational chair tests (n=3), Group 2 – otolith dysfunction only per SVV and/or VEMP test (n=4), Group 3 – both canal and otolith dysfunction (n=6). Subjects completed the descriptive symptom index (DSI) and the dizziness handicap inventory (DHI) to measure subjective impairments. Computerized dynamic posturography, dynamic gait index (DGI) and other walking balance tests were used to quantify postural control impairments. Descriptive, frequency analysis and non-parametric ANOVA were completed. Results: Severity of symptoms was not affected by time since onset. Although differences between groups were not significant, trends were evident. Rotary symptoms predominated in those with canal deficits, whereas linear symptoms predominated in those with otolith deficits. Furthermore, only those with otolith deficits had scores on the DHI indicating severe impairments. Similarly, failing DGI scores were noted in 60% and 80% of those with canal and otolith deficits, respectively. Most canal only deficits passed all posturography conditions, whereas 75% of those with otolith only deficits failed condition 5, and 50% of those with canal and otolith deficits failed at least 2 conditions. Conclusions: Patients with vestibular dysfunction may have deficits of canals only, otolith only or both. The severity of symptoms was more severe, and persistence of postural control deficits was predominant, in patients with otolith deficits. Clinical Relevance: Distinguishing impairments associated with canal versus otolith dysfunction in clinical practice can help direct the selection of appropriate diagnostic tests, improve diagnosis and assist in the development of the most efficacious treatment strategies. Future research should examine whether the vestibular substrate involved affects treatment outcome.