Instrumented functional reach test differentiates individuals at high risk for Parkinson's disease from controls.

Sandra E Hasmann,David Weiss,Ulrich Lindemann,Johannes Streffer,Walter Maetzler,Daniela Berg,Markus A Hobert,Inga Liepelt-Scarfone

doi:10.3389/fnagi.2014.00286

Abstract

The functional reach (FR) test as a complex measure of balance including limits of stability has been proven to differentiate between patients with Parkinson’s disease (PD) and controls (CO). Recently, it has been shown that the instrumentation of the FR (iFR) with a wearable sensor may increase this diagnostic accuracy. This cross-sectional study aimed at investigating whether the iFR has the potential to differentiate individuals with high risk for PD (HRPD) from CO, as the delineation of such individuals would allow for, e.g., early neuromodulation. Thirteen PD patients, 13 CO, and 31 HRPD were investigated. HRPD was defined by presence of an enlarged area of hyperechogenicity in the mesencephalon on transcranial sonography and either one motor sign or two risk and prodromal markers of PD. All participants were asked to reach with their right arm forward as far as possible and hold this position for 10 s. During this period, sway parameters were assessed with an accelerometer (Dynaport, McRoberts) worn at the lower back. Extracted parameters that differed significantly between PD patients and CO in our cohort [FR distance (shorter in PD), anterior–posterior and mediolateral acceleration (both lower in PD)] as well as JERK, which has been shown to differentiate HRPD from CO and PD in a previous study, were included in a model, which was then used to differentiate HRPD from CO. The model yielded an area under the curve of 0.77, with a specificity of 85%, and a sensitivity of 74%. These results suggest that the iFR can contribute to an assessment panel focusing on the definition of HRPD individuals.

Highlights

There is a great need for biomarkers in the prodromal phase of Parkinson’s disease (PD) because valid definitions of this phase, and its progression would open entirely new opportunities for treatment and even prevention of neurodegeneration (Postuma et al, 2012a; Berg and Bandmann, 2013; Wang et al, 2013; Lerche et al, 2014)
The model yielded an area under the curve of 0.77, with a specificity of 85%, and a sensitivity of 74%. These results suggest that the instrumentation of the FR (iFR) can contribute to an assessment panel focusing on the definition of high risk for PD (HRPD) individuals
No significant differences could be detected for the following parameters: area of sway, velocity (AP and ML), JERK (AP and ML), and mean power frequency (p > 0.05, Table 2)

Summary

Introduction

There is a great need for biomarkers in the prodromal phase of Parkinson’s disease (PD) because valid definitions of this phase, and its progression would open entirely new opportunities for treatment and even prevention of neurodegeneration (Postuma et al, 2012a; Berg and Bandmann, 2013; Wang et al, 2013; Lerche et al, 2014). Motor parameters seem to be promising for this purpose as subtle motor changes in individuals at high risk for PD (HRPD) may occur several years before clinical diagnosis can be made. This has been shown for distal (Gaenslen et al, 2011; Postuma et al, 2012b) as well as for axial motor symptoms such as gait and balance (Mirelman et al, 2011; Maetzler and Hausdorff, 2012; Maetzler et al, 2012). One study (Smithson et al, 1998) found that PD patients have a shorter FR distance (~4 cm) than CO, which has been confirmed by another study

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