Gait initiation is impaired in subjects with Parkinson’s disease in the OFF state: Evidence from the analysis of the anticipatory postural adjustments through wearable inertial sensors

Abstract

People with Parkinson’s disease (PD) typically demonstrate impaired anticipatory postural adjustments (APAs) that shift the body center of mass forward (imbalance) and over the stance leg (unloading) prior to gait initiation. APAs are known to be smallest when people with PD are in their OFF-medication state compared to ON-medication or healthy controls. The aim of this pilot study is to validate a previously developed method for the assessment of gait initiation on PD patients in OFF state with body-worn, inertial sensors. Ten subjects with mild-to-moderate idiopathic PD and twelve healthy controls of similar age performed three gait initiation trials. The spatio-temporal parameters of APAs were extracted from three wearable sensors, placed on the shins and on the lower back, and validated with two force plates. Temporal parameters extracted from sensors and force plates, as well as the trunk medio-lateral acceleration and the correspondent displacement of the center of pressure, were significantly correlated. Subjects with PD showed hypometric adjustments in the medio-lateral direction (p-value < 0.003) and increased duration of the unloading phase (p-value = 0.04). The unloading phase was significantly longer than the imbalance (p-value = 0.003) only in subjects with PD. The validity of the method of quantifying APAs from inertial sensors was confirmed in PD subjects by comparison with force plates. Sensitivity in discriminating PD patients from healthy controls was proven by both spatial and temporal parameters. Objective measures of gait initiation deficits with wearable technology provides valuable instrument for the assessment of gait initiation in clinical environments.

Gait Analysis in Parkinson’s Disease: An Overview of the Most Accurate Markers for Diagnosis and Symptoms Monitoring

“…Accelerometers, gyroscopes and magnetometers can be the component of the same inertial measurement unit (IMU) device ( Figure 5), one of the most widely used type of sensors in gait analysis especially in PD [33,53]. It can measure velocity, acceleration, orientation and gravitational forces and can be used to study gait initiation [54], assess standing balance [55] and quantify bradykinesia [56]. Accelerometers are composed of a mechanical sensing element with a proof mass attached to a mechanical suspension system, with respect to a reference frame, that can be forced to deflect by the inertial force according to the acceleration of gravity.…”

“…Accelerometers, gyroscopes and magnetometers can be the component of the same inertial measurement unit (IMU) device ( Figure 5 ), one of the most widely used type of sensors in gait analysis especially in PD [ 33 , 53 ]. It can measure velocity, acceleration, orientation and gravitational forces and can be used to study gait initiation [ 54 ], assess standing balance [ 55 ] and quantify bradykinesia [ 56 ].…”

Relationship between Amount of Daily Movement Measured by a Triaxial Accelerometer and Motor Symptoms in Patients with Parkinson’s Disease

“…In recent years, new technology-based methods for the assessment of PD have been proposed and developed [4][5][6][7][8][9]. Some employ wearable sensors, such as accelerometers, gyroscopes, magnometers, barometers, light sensors, and global positioning systems [10].…”

Investigation of Anticipatory Postural Adjustments during One-Leg Stance Using Inertial Sensors: Evidence from Subjects with Parkinsonism

“…IMUs were placed directly on the skin and fixed with self-adhering elastic (Coban) bandages. Data were recorded at a sampling frequency of 128 Hz and later downsampled at a frequency of 50 Hz in accordance with previous studies ( 26 , 28 – 30 ).…”

“…This wearable technology allows clinicians to easily perform an instrumental evaluation of motor deficits during routine exams. For example, wearable inertial measurement units (IMUs) have been demonstrated to be effective for the assessment of weak APAs that precede step initiation ( 26 – 30 ) and step climbing ( 28 ) in iPD. Algorithms to quantify dynamic APAs and static balance associated with OLS are needed.…”