An In–Laboratory Validity and Reliability Tested System for Quantifying Hand–Arm Tremor in Motions

Abstract

Despite the advancement of the tremor assessment systems, the current technology still lacks a method that can objectively characterize tremors in relative segmental movements. This paper presents a measurement system, which quantifies multi-degrees-of-freedom coupled relative motions of hand-arm tremor, in terms of joint angular displacement. In-laboratory validity and reliability tests of the system algorithm to provide joint angular displacement was carried out by using the two-degrees-of-freedom tremor simulator with incremental rotary encoder systems installed. The statistical analyses show that the developed system has high validity results and comparable reliability performances using the rotary encoder system as the reference. In the clinical trials, the system was tested on 38 Parkinson's disease patients. The system readings were correlated with the observational tremor ratings of six trained medical doctors. The moderate to very high clinical correlations of the system readings in measuring rest, postural and task-specific tremors add merits to the degree of readiness of the developed tremor measurement system in a routine clinical setting and/or intervention trial for tremor amelioration.

Biomechanical System Versus Observational Rating Scale for Parkinson’s Disease Tremor Assessment

“…The biomechanical system readings in RMS Δθ joint were validated with the average ratings of six doctors. The results show that most of the measurement readings can be used to explain the variability of the doctors’ rating in assessing tremor during rest and outstretching postures 15 .…”

“…Postprocessing of these data was carried out to compute the joint angle 15 . In this system, the coupling effects of wrist flexion-extension and wrist abduction-adduction, as well as elbow pronation-supination and elbow flexion-extension are considered.…”

“…wrist flexion–extension, wrist abduction–adduction, elbow pronation–supination and elbow flexion–extension was then computed for its root mean square (RMS) throughout the whole measurement before statistical analyses were carried out. The biomechanical system quantification method was previously validated with a high–precision angular encoder system installed on a tremor simulator in addition to being correlated with the doctors’ observational ratings 15 .…”

“…In a previous clinical study, the tremors of PD patients were measured using the same instruments and the same camera settings were applied to record the tremor conditions 15 . Six doctors from the Neurology Units of Penang Hospital and Hospital Universiti Sains Malaysia evaluated the video-recorded tremor using MDS–UPDRS and their ratings were averaged.…”

“…Prior to the reliability analyses, the predicted ratings in PD subgroup were obtained with the multiple linear regression models relating the system readings of four motions and six doctors’ ratings 15 . For evaluating the test–retest reliabilities of the tools, relative reliability and absolute reliability were analysed.…”