A NEW ACTIGRAPH FOR LONG-TERM REGISTRATION OF THE DURATION AND INTENSITY OF TREMOR AND MOVEMENT

Actigraphy, the long-term measurement of human movement with a small s olid 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 inf ormation on movement type or intensity, and cannot be used in subjects suffering from tremor. The present paper describes a new type of acti graph, that has been developed primarily for the long term evaluation of motor symptoms in Parkinson patients. The device is the first to di scriminate tremor from other movements and to assess both duration and intensity of the two types of movement. It is based on a Motorola 68H C805B6 microcontroller and contains: an accelerometer, programmable ga in stages, programmable low- and highpass filters, a programmable leve l comparator, a peak detector, interface circuits, a real time clock, data storage, and control circuitry. The micro-controller performs a p eriod amplitude sequence analysis (PASA) on the conditioned accelerome ter signal, and stores four output variables (tremor duration, tremor amplitude, movement duration, and movement amplitude) at the end of pr ogrammable time intervals. The analysis of fluctuations in the motor s ymptoms of, e.g., Parkinson patients using this actigraph can be of gr eat help in the pharmacological management of symptoms.