Objective: To explore the possibility of using an automated bed side test of motor response inhibition – Stop Signal Reaction Time (SSRT) while optimizing DBS parameters.

Background: Deep brain stimulation (DBS) of STN is increasingly used in the treatment of Parkinson’s disease(PD), across the globe. The effectiveness of the DBS treatment depends to a large extent on periodic programming of the device. The optimum setting of DBS parameters is determined by clinical assessments of the motor score. The hyper-direct pathway connecting the frontal cortex and STN is strongly implicated in the control of motor response inhibition. We therefore hypothesize, that optimal STN DBS will normalize the SSRT in PD patients by activating this pathway.

Method: We developed a stand-alone battery-operated box with one green, one red LEDs and a press-button on it. The patients were instructed to release the button as soon as the green LED flashed. Randomly, in some trials (45 out of total 180 trials) the red LED flashed just after the green LED. In those trials the patients were instructed to inhibit the activity of releasing the button. These responses can be statistically analysed to obtain an objective statistical measure- Stop Signal Reaction Time (SSRT) indicating the efficiency of response inhibition. We assessed the SSRT and UPDRS III in three situations. Initially, when the patient came to the clinic complaining of motor slowness or deteriorated tremor in existing DBS setting, after turning off the DBS and after optimizing the DBS programming.

Results: We included 7 consecutive Parkinson’s patients with STN-DBS leads in situ. The baseline average UPDRS III and SSRT was 26 ms (SD 12 ms) and 331 ms (SD 71 ms) respectively. We observed an increase in the UPDRS III (37, SD 17) and significant (p 0.018) prolongation of the SSRT (412 ms, SD 92 ms), as expected after turning off the DBS. The UPDRS III reduced (11, SD 8) and SSRT shortened (285 ms, SD 45 ms) significantly (p 0.018) from baseline after optimizing the DBS settings.

Conclusion: SSRT could be developed as a simple, objective and quantitative bedside tool for optimizing DBS parameters. Such an approach could be implemented with minimal training.

« Back to 2019 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/motor-response-inhibition-a-potential-tool-to-determine-optimum-stn-dbs-setting/