A new actigraph for long-term registration of the duration and intensity of tremor and movement

Abstract

Actigraphy, the long-term measurement of human movement with a small solid state recorder, is gaining acceptance as a useful method in many research fields. Currently available actigraphs assess or estimate the movement duration per time interval. However, the output gives no information on movement type or intensity, and cannot be used in subjects suffering from tremor. The present paper describes a new type of actigraph, that has been developed primarily for the long-term evaluation of motor symptoms in Parkinson patients. The device is the first to discriminate tremor from other movements and to assess both duration and intensity of the two types of movement. It is based on a Motorola 68HC805B6 microcontroller and contains: an accelerometer, programmable gain stages, programmable low- and highpass filters, a programmable level comparator, a peak detector, interface circuits, a real time clock, data storage, and control circuitry. The micro-controller performs a period amplitude sequence analysis (PASA) on the conditioned accelerometer signal, and stores four output variables (tremor duration, tremor amplitude, movement duration, and movement amplitude) at the end of programmable time intervals. The analysis of fluctuations in the motor symptoms of, e.g., Parkinson patients using this actigraph can be of great help in the pharmacological management of symptoms.

Motion pattern and posture: Correctly assessed by calibrated accelerometers

“…Lummel, 1994), and movement pathologies-for example, the quantification ofamplitude, frequency, and occurrence time of tremor in Parkinson's disease and its relation to posture and motion Smeja et al, 1999;van Someren et al, 1998).…”

Objective Evaluation of the Severity of Parkinsonism Using Power-Law Temporal Auto-Correlation of Activity

“…Improvement of ambulatory activity monitors (actigraph) has enabled precise calibration and storage of thousands of activity measurements acquired at predetermined times, hence enabled longterm recording of patient's movement during ordinary daily living (Katayama, 2001;Korte et al, 2004;Mormont et al, 2000;Okawa et al, 1995;Teicher, 1995;Tuisku et al, 2003;van Someren et al, 1996). It has been demonstrated that use of these devices is useful for the quantitative estimation of human behavior properties in normal subjects and patients with a variety of diseases, including depression, pain syndrome, and PD (Jean-Louis et al, 2000;Korszun et al, 2002;Nakamura et al, 2007;Ohashi et al, 2003;Pan et al, 2007;van Someren et al, 1993;1998;. However, because the pattern of daily activity greatly influences the recording with accelerometers, recorded activity levels may not adequately reflect the disease severity (Fig 1).…”

Virtual cues and functional mobility of people with Parkinsons disease: A single-subject pilot study

“…An alternative form of data collection, besides use of daily activity diaries, would also be beneficial. Wearable technology that can measure different types of movement for people with PD is currently being researched [32]. This technology would help provide an objective and accurate picture of the activity and gait patterns of people with PD.…”