Motor Subtypes of Parkinson’s Disease Can Be Identified by Frequency Component of Postural Stability

Abstract

Parkinson’s disease (PD) can be divided into two subtypes based on clinical features—namely tremor dominant (TD) and postural instability and gait difficulty (PIGD). This categorization is important at the early stage of PD, since identifying the subtypes can help to predict the clinical progression of the disease. Accordingly, correctly diagnosing subtypes is critical in initiating appropriate early interventions and tracking the progression of the disease. However, as the disease progresses, it becomes increasingly difficult to further distinguish those attributes that are relevant to the subtypes. In this study, we investigated whether a method using the standing center of pressure (COP) time series data can separate two subtypes of PD by looking at the frequency component of COP (i.e., COP position and speed). Thirty-six participants diagnosed with PD were evaluated, with their bare feet on the force platform, and were instructed to stand upright with their arms by their sides for 20 s (with their eyes open and closed), which is consistent with the traditional COP measures. Fast Fourier transform (FFT) and wavelet transform (WT) were performed to distinguish between the motor subtypes using the COP measures. The TD group exhibited larger amplitudes at the frequency range of 3–7 Hz when compared to the PIGD group. Both the FFT and WT methods were able to differentiate the subtypes. COP time series information can be used to differentiate between the two motor subtypes of PD, using the frequency component of postural stability.

Postural Stability and Cognitive Performance of Subjects With Parkinson’s Disease During a Dual-Task in an Upright Stance

“…In relation to this last factor, the characterization of PD participants in the two most widely used clinical phenotypes, dominant tremor versus postural instability/gait difficulty (Stebbins et al, 2013), would allow for a better understanding of the influence of PD on attentional demands of control of standing stability. In this sense and considering future studies, complementing the measures of the COP in the time domain with the measures in the frequency domain will allow us to use methods such as the fast Fourier transformation and the wavelet waveform for a more objective differentiation of the two motor subtypes (Rezvanian et al, 2018).…”

Detection of postural control in early Parkinson’s disease: Clinical testing vs. modulation of center of pressure

“…Spectral analysis of the COP has revealed that the frequency of HC and patients with neurodegenerative diseases is different. Specifically, HC have a dominant sway from 0.1-0.5 Hz [10][11][12], whereas in moderate PD the dominant frequency manifests at 0-2 Hz and 3-7 Hz [13]. To date most posturography studies in PD focus on the basic spatiotemporal measures (see review by Kamieniarz et al [14]).…”

Feasibility of Home-Based Automated Assessment of Postural Instability and Lower Limb Impairments in Parkinson’s Disease

“…Several studies have found that, during the quite stance, the continuous movement of the center of mass (CoM), named “postural sway“ or “body sway”, contributes to balance control [ 39 , 40 , 41 ]. Alterations of body sway can reveal balance dysfunctions in PD, long before their clinical assessment [ 42 ] and they can be used to differentiate between motor subtypes of PD [ 43 ]. Recently, low cost RGB-Depth devices as Microsoft Kinect v2, have been used to assess objectively balance dysfunctions [ 44 , 45 , 46 ].…”