AMBULATORY MONITORING OF TREMOR AND OTHER MOVEMENTS BEFORE AND AFTER THALAMOTOMY - A NEW QUANTITATIVE TECHNIQUE

Tremor, e.g. in Parkinson patients, often shows large spontaneous fluc tuations in severity over the day, to such an extent that a short obse rvation is usually not sufficient to assess the overall severity or th e effect of a treatment. Since momentary impressions of the tremor can thus be misleading, long-term ambulatory recordings would be helpful in the evaluation of severity and treatment effectiveness. As existing methods for long-term tremor registration have several shortcomings, a new method is proposed: an algorithm was designed to discriminate tr emor from other movements and to describe the amount (i.e. the proport ion of tremor or movements per time unit) as well as the intensity (i. e. average acceleration amplitude) of the two types of movement. In th e evaluation of the severity of tremor both the amount and intensity o f tremor episodes are of importance. The algorithm was tested on 24-h analog tape recordings of wrist-movement in 10 young and 10 aged contr ols, as well as in 8 patients with tremor - both before and after a tr emor relieving thalamotomy. The algorithm scored movements as 'tremor' exclusively in patients prior to the operation. Fluctuations in tremo r severity over the day were detected, and tremor could be discriminat ed from non-pathological movements. Moreover, following thalamotomy, m otor slowing (bradykinesia) was detectable using this algorithm. Based on these test results, a miniaturized device in wrist-watch format is now being developed for long-term registrations.