Objective: To test whether DBS parameters in chronically stimulated Parkinson´s disease (PD) patients chosen by clinical criteria are congruent with DBS parameters as derived from fitting a VTA model to the individual MRI based segementation of the STN by an expert neurologist.

Background: Programming of deep brain stimulation (DBS) for the treatment of movement disorders can be laborious. Amplitude (voltage or current), pulse width and frequency become stepwise adapted according to clinical feedback, often at different contacts oft the electrode. Technical innovations (lower pulse widths, current steering between contacts, directed current steering via segmented leads) further expand the parameter space. It is therefore impossible to determine the individually best fitting stimulation parameters by testing all options clinically in a reasonable amount of time. Computational algorithms can model the volume of tissue activated (VTA) by given stimulation parameters and may help to identify stimulation settings that are worth of evaluating clinically.

Methods: 15 PD patients were evaluated one year after chronic DBS in the subthalamic nucleus (STN). A fusion of the preoperative MRI- and postoperative CT-scans were done with SureTune™ software. The STN was outlined on T2 weighted MRI scans and a 3D model comprising the individual position of the DBS electrode was reconstructed. An expert neurologist (JV), blinded to the clinical data of the patient tried to fit a VTA for each hemisphere covering the sensorimotor STN by adjusting electrode polarity and amplitude (pulse width 60µs, frequency 130Hz). These parameters were then compared to the clinical settings.

Results: In 20 of 30 electrodes (67%) the contact chosen for anatomical DBS was different from the contact for clinical DBS and in 65% more proximal (12 electrodes one contact, one electrode two contacts). The stimulation amplitude differed in 23 of 30 electrodes of more than 0.3mA with higher amplitudes in 48% of clinical DBS (11 electrodes).

Conclusions: There was a substantial difference between stimulation parameters chosen upon clinical versus anatomical criteria with a trend to deeper contacts and higher amplitudes in clinical programming. A systematic comparison of chronic outcomes (efficacy, efficiency and adverse effects) of model based and clinical programming parameters is needed.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/comparison-of-clinically-derived-and-model-based-programming-parameters-of-subthalamic-nucleus-stimulation-in-parkinsons-disease/