Article
Objective analysis of amplitude and frequency of tremor after discontinuation of subthalamic deep brain stimulation in patients with Parkinson’s disease
Analyse von Tremoramplitude und Tremorfrequenz nach dem Ausschalten der chronischen tiefen Hirnstimulation des Nucleus substhalamicus bei Patienten mit Morbus Parkinson
Search Medline for
Authors
Published: | May 4, 2005 |
---|
Outline
Text
Objective
To quantify the time course of the reappearance of tremor amplitude and frequency after discontinuation of subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson’s disease (PD), using a computerised 3D ultrasound-based measuring method combined with surface electromyography of forearm muscles.
Methods
Eight patients (mean age 67.5±4,8 years) suffering from idiopathic PD were evaluated in medication off state 4-14 months after chronic bilateral STN DBS. Tremor amplitude and frequency were measured at baseline and at 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25 and 30 minutes after discontinuation of STN DBS. In addition, after switching DBS on, the mean latency the disappearance of tremor was determined.
Results
After discontinuation of STN DBS tremor rapidly reappears with a mean latency of 7.0 seconds (±0.9). Disappearance of tremor after switching DBS on was even faster at a mean latency of 3.7 seconds (±0.6). In three patients, a significant change of tremor frequency within two seconds after switching DBS on was found. Tremor amplitude quickly increased after discontinuation of STN DBS, reaching a maximum amplitude after 2 minutes (32.1 mm ±7.0), compared to baseline: 1.5 mm ±0.7). In the sequel, tremor amplitude gradually dropped to a mean level of 20.2 mm (±6.8) 10 minutes after switching STN DBS off and remained stable during the following 20 minutes of DBS discontinuation.
Conclusions
After discontinuation of STN DBS in PD, tremor reappeared rapidly within seconds, reaching a maximum amplitude after 2-3 minutes of discontinuation, and in some patients STN DBS almost immediately changed tremor frequency. These findings support the hypothesis, that DBS acts by direct interference with the basal ganglia loops involved in tremor.