Shifting from constant-voltage to constant-current in Parkinson's disease patients with chronic stimulation

Objective. To evaluate safety and efficacy of shifting stimulation settings from constant-voltage (CV) to constant-current (CC) programming in patients with Parkinson disease (PD) and chronic subthalamic nucleus deep brain stimulation (STN DBS). Methods. 20 PD patients with chronic STN DBS set in CV programming were shifted to CC and followed for three months; the other stimulation settings and the medication regimen remained unchanged. Side effects, motor, non-motor, executive functions and impedance were assessed at baseline and during follow-up. Results. No adverse events were observed at time of change in programming or during CC stimulation. Motor and non-motor measures remained unchanged at follow-up despite impedance decreased. Compared to baseline, cognitive assessment showed improvement of inhibition processes. Conclusions. The shifting strategy was well tolerated and the clinical outcome was maintained with no need to adjust stimulation settings or medications notwithstanding a decrease of impedance. Improvement of inhibition processes towards normality is an important feature to consider

Impulse control behaviours in patients with Parkinson's disease after subthalamic deep brain stimulation: de novo cases and 3-year follow-up

OBJECTIVE: To document the occurrence of impulse control behaviours (ICBs) in patients with Parkinson's disease after 3 years of continuous deep brain stimulation (DBS) of the subthalamic nucleus (STN). METHODS: Detailed neurological and ICB assessments were performed before STN DBS and up to 3 years after implant. RESULTS: 13 out of 56 patients (23.2%) had ICBs at baseline; they took higher doses of dopamine agonists (DAA). Three years after implant 11 had fully remitted with a 60.8% reduction of DAA medication; the remaining two, who had a similar medication reduction, had only compulsive eating, having recovered from hypersexuality. Six of the 43 patients without ICBs at baseline (14%) developed transient de novo ICBs after implant; none of them had ICBs at the 3-year observation. CONCLUSIONS: ICBs were abolished in patients 3 years after STN DBS and DAA dosages were lowered. New ICBs may occur after implant and are transient in most cases. Compulsive eating may be specifically related to STN stimulation

Subthalamic involvement in monetary reward and its dysfunction in parkinsonian gamblers

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