![]() ![]() Based on preoperative T1 magnetic resonance imaging and post-operative computed tomography scans, the 2nd lowest contacts were located in the PSA. Thus, we aimed to evaluate the effect of short pulse and directional DBS in the VIM / PSA in PD patients and to compare DBS effects with those in ET patients.įull size table Surgical procedure and definition of electrode positionĪll patients were implanted with the Infinity DBS system (Abbott Medical Neuromodulation Division, Plano, TX, USA) according to standard surgical procedures at our center as previously described in detail 17. ![]() It is of interest, whether the effects of VIM/PSA-DBS depend on the preexisting pathophysiological state of the cerebello-thalamo-cortical circuit in these two disease conditions and whether the use of short pulse and directional stimulation can optimize potential effects and side effects in both tremor entities, parkinsonian and essential tremor. The ventral intermediate nucleus (VIM) is a main relay nucleus embedded in the cerebello-thalamo-cortical circuit and an optimal target to interfere with circuit oscillations by DBS. In contrast, in ET the abnormality seems to be within the cerebello-thalamo-cortical network itself with a dysfunctional motor controller which sets off the oscillation 16. Thus it was proposed, that the basal ganglia circuit might trigger the cerebello-thalamo-cortical network to oscillate, resulting in tremor. FDG-PET and functional MRI studies suggest that activity changes in the basal ganglia network involving the putamen and globus pallidus are associated to tremor onset while cerebellum, thalamus and the motor cortex correlate with tremor amplitude 16. Parkinsonian tremor might be elicited by the combination of nigrostriatal degeneration and cerebello-thalamic circuit dysfunction. The pathophysiology of parkinsonian and essential tremor is quite different 15, 16. To date, the use of novel stimulation algorithms in PD patients with VIM/PSA-DBS has not been assessed. For both stimulation modes, it has been recently demonstrated that the therapeutic window can be enhanced in ET patients with VIM/PSA-DBS 9, 10, 11, 12 or PD patients with STN-DBS 13, 14. On the other hand, a spatially restricted, more focal, directed electric field can be applied via segmented electrodes. On the one hand, stimulation with short pulses (< 60 µs) is assumed to target specific nerve fibers along their different neurophysiological properties. In recent years, new forms of stimulation have expanded the therapeutic options. VIM/PSA-DBS proved an effective treatment to suppress tremor, but its efficacy is limited by stimulation induced adverse effects 6, 7, 8. While the subthalamic nucleus (STN) or the globus pallidus internus (GPi) are often targeted in PD due to additional effects on bradykinesia and rigidity, VIM/PSA-DBS is preferred in elderly PD patients with lateralized tremor or slight cognitive impairment. In both disease conditions, deep brain stimulation (DBS) in the area of the ventral intermediate nucleus (VIM) and the posterior subthalamic area (PSA) is a good treatment option in case of drug therapy failure 4, 5. Parkinsonian (PD) and essential tremor (ET) are beyond the most common tremor syndromes 1, 2, 3 with considerable impact on patients’ quality of life. Trial registration: The study was registered in the DRKS (ID DRKS00025329,, German Clinical Trials Register, DRKS-Deutsches Register Klinischer Studien). In PD and ET tremor, short pulse or directional VIM/PSA-DBS is an effective and well tolerated therapeutic option. Tremor reduction was more pronounced in PD than in ET due to a limited DBS effect on intention and action-specific drawing tremor in ET. In both patient groups, all three DBS stimulation modes reduced the total tremor score compared to STIM OFF, whereas stimulation-induced ataxia was reduced by oDBS30 and partially by dDBS60 compared to oDBS60. ![]() Tremor severity and ataxia were assessed in four different stimulation conditions in a randomized order: DBS switched off (STIM OFF), omnidirectional stimulation with 60 µs (oDBS60), omnidirectional stimulation with 30 µs (oDBS30), directional stimulation at the best segment with 60 µs (dDBS60). We recruited six PD patients (70.8 ± 10.4 years) and seven ET patients (64.4 ± 9.9 years) with implanted VIM/PSA-DBS in a stable treatment condition (> 3 months postoperatively). The aim of this study was to assess the effects of novel stimulation algorithms of deep brain stimulation (short pulse and directional stimulation) in the ventrointermediate thalamus and posterior subthalamic area (VIM/PSA-DBS) on tremor in Parkinson’s disease (PD) and to compare the effects with those in essential tremor (ET). ![]()
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