Do clinical scales of balance reflect turning abnormalities in people with Parkinson's disease?

BACKGROUND AND PURPOSE It is well known that people with Parkinson's disease (PD) have significant difficulty turning, and that such difficulty is related to freezing episodes and falls. However, it is unclear how clinicians should evaluate turning. The purpose of this exploratory study was to determine whether the common clinical assessment instruments reflect turning deficits in persons with PD compared with an instrumented measure. METHODS Forty-six participants with PD (23 with mild PD, and 23 with severe PD), and 40 healthy controls were assessed using the Berg Balance Scale (Berg), Tinetti Mobility Test (Tinetti), Activities-Specific Balance Confidence Scale, and the new instrumented Timed Up & Go test using wearable inertial sensors. RESULTS Turns during the instrumented Timed Up & Go test showed significant differences among groups (χ2 = 43.6, P < 0.0001). Specifically, controls and mild PD (P < 0.001) and controls and severe PD (P < 0.00001). The number of steps (χ2 = 32.1; P < 0.0001) and peak speed (χ2 = 31.9; P < 0.0001) during turning were significantly different among all groups. Clinical scales were less likely to detect these differences. Of the clinical scales, the Berg was best able to detect differences between control and mild PD groups. Correlations between clinical measures of balance and instrumented turning were moderate but significant. CONCLUSIONS We show evidence that turning is impaired, even in mildly impaired participants with PD and that this deficit is not obviously reflected in common clinical scales of balance such as the Berg or Tinetti. It may be more useful for a clinician to examine particular items within the Berg or the turning component of the TUG if turning difficulty is suspected.