Differential actigraphy for monitoring asymmetry in upper limb motor activities

• Published in: Physiological measurement 2016-10, Vol.37 (10), p.1798-1812
• Main Authors: Rabuffetti, M, Meriggi, P, Pagliari, C, Bartolomeo, P, Ferrarin, M
• Format: Article
• Language: English
• Subjects: accelerometer; actigraphy; asymmetry; handedness; upper limbs; wearable sensors
• ISSN: 0967-3334; 1361-6579
• DOI: 10.1088/0967-3334/37/10/1798

Most applications of accelerometry-based actigraphy require a single sensor, properly located onto the body, to estimate, for example, the level of activity or the energy expenditure. Some approaches adopt a multi-sensor setup to improve those analyses or to classify different types of activity. The specific case of two symmetrically placed actigraphs allowing, by some kind of differential analysis, for the assessment of asymmetric motor behaviors, has been considered in relatively few studies. This article presents a novel method for differential actigraphy, which requires the synchronized measurements of two triaxial accelerometers (programmable eZ430-Chronos, Texas Instruments, USA) placed symmetrically on both wrists. The method involved the definition of a robust epoch-related activity index and its implementation on-board the adopted programmable platform. Finally, the activity recordings from both sensors allowed us to define a novel asymmetry index AR24 h ranging from  −100% (only the left arm moves) to  +100% (only the right arm moves) with null value marking a perfect symmetrical behavior. The accuracy of the AR24 h index was 1.3%. Round-the-clock monitoring on 31 healthy participants (20-79 years old, 10 left handed) provided for the AR24 h reference data (range  −5% to 21%) and a fairly good correlation to the clinical handedness index (r  =  0.66, p