Time in Parkinson’s disease: Clinical and preclinical markers

Methods: Five meters of gait were assessed in 14 healthy controls (61.4 ± 10.6 years old) and in 28 patients at early-to-moderate stages of idiopathic PD (60.0 ± 9.5 years old) with a single body-fixed-sensor (BFS) placed on the lower back. Differences between groups in step-by-step kinematic parameters were evaluated to understand gait impairments in the PD group. Moreover, a discriminant model between groups was built from a subset of significant and independent parameters and based on a 10-fold cross-validated model. Results: The discriminant model correctly classified a total of 89.5% participants with four kinematic parameters. The sensitivity of the model was 95.8% and the specificity was 78.6%. This indicates that the proposed method permitted to reasonably recognize idiopathic PD-associated gait from 5-m walking assessments. Conclusions: The results motivate further investigation on the clinical utility of short episodes of gait assessment with BFS. 61 Based on the scientific article: M.E. Micó-Amigo, I. Kingma, G.S. Faber, A. Kunikoshi, J.M.T. van Uem, R.C. van Lummel, J.H. van Dieën. Is the assessment of 5 meters of gait with a single body-fixed-sensor enough to recognize idiopathic Parkinson’s disease-associated gait? Annals of Biomedical Engineering 2016; 13:1–12. Chapter 3 | Introduction 62 Parkinson ́s disease (PD) is among the most common neurodegenerative diseases in Europe, with an estimated prevalence of 1.6% in populations above 65 years old.58 The incidence of PD rises with age237 and imposes an annual burden on European healthcare systems that approximately ranges between 2.600 and 19.000 € per patient.306, 307 Thus, as the population’s longevity increases, it is expected that PD will impose a growing social and economic burden on societies.222 Consequently, an increased use of healthcare resources for PD over the following years is expected, which will likely have a significant impact on social security and healthcare systems.306 The degeneration of the basal ganglia and the loss of dopaminergic innervations in PD can cause body rigidity, resting tremor and postural instability.172 Moreover, they may compromise the speed, automaticity and fluidity or smoothness of movements;43 reflected in symptoms such as bradykinesia and hypokinesia.172 These deficits are frequently present during gait in patients with PD and can be quantitatively and objectively assessed,43 providing information regarding the clinical status of the patient. The assessment of gait is part of a widely used clinical rating scale for PD (Unified Parkinson's Disease Rating Scale, UPDRS)93 and is used to monitor and regulate the effects of interventions such as medication, deep-brain-stimulation (DBS) and rehabilitation.170 Furthermore, since motor impairments such as trunk rigidity and gait dysfunction are often present at initial stages of the disease, their assessment might lead to earlier and improved diagnosis.172 Altogether, the valid assessment of movement in patients with PD is an important step in addressing motor symptoms and improving clinical management.306 Altered movement patterns in patients with PD can be detected by analysing signals recorded with accelerometers and gyroscopes, both integrated into a single device that is located on the lower back.170 These signals represent the overall motion pattern given the proximity of the sensor to the centre of mass.8 Their processing enables the assessment of trunk stability, balance control and fall risk.246 In addition, the analysis of the recorded signals permits the identification of gait events197 and the extraction of spatio-temporal gait parameters that are sensitive to patients with motor symptoms of PD.61 Accelerometers and gyroscopes, in this context also known as body-fixed-sensors (BFS), are small, light-weight, low-cost sensors with good portability and low-power consumption.63 Therefore, they are easily applicable and enable the assessment of movement patterns in a clinical setting; potentially enhancing objectivity, sensitivity and reliability of clinical tests.172 BFS can be used for the assessment of short episodes of gait, which provide information (gait speed, gait cycle time and stride velocity) that differs from Introduction