Objective: The objectives of this study were to investigate suppression of dyskinesia in Parkinson’s disease (PD) patients who had previously undergone deep brain stimulation (DBS) surgery by delivering electrical stimulation dorsal to the subthalamic nucleus (STN), and secondly, to determine the underlying neural circuits that when stimulated, suppressed dyskinesia.

Background: Although DBS may significantly reduce dyskinesia in most PD patients following surgery, some patients either continue to have or develop new dyskinesia symptoms. Recent reports indicate delivery of stimulation via more dorsal STN DBS contacts may decrease the severity of dyskinesia. It is unknown what neuronal structures or tracts that once stimulated, are responsible for suppression of dyskinesia symptoms.

Methods: Retrospective patient chart data was reviewed for 15 PD patients with bilateral STN DBS who began to experience levodopa-induced dyskinesia. UPDRS-IV dyskinesia sub-scores were used to quantify clinical responses and significance was determined (two-tailed paired t-test). Levodopa equivalent daily dosages (LEDD) before and after the new stimulation settings were analyzed for significant changes. Stimulation was delivered via proximal DBS contacts using variable parameters (monopolar, bipolar, simultaneous or interleaved) depending on the patients’ clinical response.

Results: Dyskinesia scores significantly (p < 0.0001) decreased in each patient after the addition of electrical stimulation to one or more of the dorsal contacts (mean±std of scores: pre stim = 6.67±3.43; post stim = 1.00±1.32; n=9 patients). Dyskinesia scores remained decreased following the addition of the dorsal contact stimulation, regardless of when the score was obtained relative to medication dosing. LEDD did not significantly change after new DBS settings (p = 0.049; n=15). Future analyses will examine the volume of tissue activated in each patient in order to identify the underlying circuits responsible for dyskinesia suppression with dorsal STN DBS.

Conclusions: In PD, the development of dyskinesia may be difficult to treat and such movements can be disturbing to the patients’ quality of life. By using current steering techniques, physicians may now be able to target dorsal STN neural tissue to help decrease dyskinesia in PD patients with STN DBS.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/suppression-of-dyskinesia-in-parkinsons-disease-by-electrical-stimulation-of-dorsal-subthalamic-nucleus-tissue/