Affiliations: [a] Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| [b]
Centre for Clinical Neurosciences and Neurological Research, St Vincent’s Hospital Melbourne, Fitzroy, VIC, Australia
| [c] Global Kinetics Corporation, Melbourne, VIC, Australia
| [d]
Bionics Institute, East Melbourne, VIC, Australia
| [e] Medical Bionics Department, The University of Melbourne, Parkville, VIC, Australia
| [f] Department of Medicine, University of Melbourne, Parkville, VIC, Australia
Correspondence:
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Correspondence to: Malcolm Horne, Kenneth Myer Building, Cnr Genetics Lane on Royal Pde, University of Melbourne, Parkville 3010, Ausralia. Tel.: +61 3 9035 6589; E-mail: E-mail: mhorne@unimelb.edu.au.
Abstract: Background: While tremor in Parkinson’s Disease (PD) can be characterised in the consulting room, its relationship to treatment and fluctuations can be clinically helpful. Objective: To develop an ambulatory assessment of tremor of PD. Methods: Accelerometry data was collected using the Parkinson’s KinetiGraph System (PKG, Global Kinetics). An algorithm was developed, which could successfully distinguish been subjects with a resting or postural tremor that involved the wrist whose frequency was greater than 3 Hz. Percent of time that tremor was present (PTT) between 09 : 00 and 18 : 00 was calculated. Results: This algorithm was applied to 85 people with PD who had been assessed clinically for the presence and nature of tremor. The Sensitivity and Selectivity of a PTT ≥0.8% was 92.5% and 92.9% in identifying tremor, providing that the tremor was not a fine kinetic and postural tremor or was not in the upper limb. A PTT >1% provide high likely hood of the presence of clinical meaningful tremor. These cut-offs were retested on a second cohort (n = 87) with a similar outcome. The Sensitivity and Selectivity of the combined group was 88.7% and 89.5% respectively. Using the PTT, 50% of 22 newly diagnosed patients had a PTT >1.0%. The PKG’s simultaneous bradykinesia scores was used to find a threshold for the emergence of tremor. Tremor produced artefactual increase in the PKG’s dyskinesia score in 1% of this sample. Conclusions: We propose this as a means of assessing the presence of tremor and its relationship to bradykinesia.
