Objective: Review and analysis of clinical and neurostimulation parameters in patients with replacement of constant-voltage non-rechargeable implantable pulse generator (CV-nrIPG) by constant-current rechargeable IPG (CC-rIPG) in a tertiary centre.

Background: Longer life expectancy in patients with Parkinson’s disease (PD) and technological improvement led to more patients with bilateral subthalamic nucleus deep brain stimulation (STN-DBS) hybrid systems.

Method: Search in clinical reports.

Results: The replacement of CV-nrIPG by CC-rIPG was performed in three patients. The final amplitude was predicted using the Ohm’s law in all cases. Only one patient needed readjustment of the parameters: 73-year-old male, 20-year evolution PD. DBS surgery in 2010 (KinetraMedtronic). IPG replacement in 2015 (ActivaPCMedtronic) without any intercurrences. A new replacement by CC-rIPG (Percept PCMedtronic) was performed in 2022 to maintain the pulse at 40s (axial symptoms). One month after the procedure the patient came to our centre in much worse clinical condition, with an unintelligible speech and an inability to walk independently. The amplitude was readjusted to half of the initial value predicted by ohm’s law with improvement of the speech and gait. The other two patients (replacement of ActivaPC by PerceptPC) remained clinically stable.

Conclusion: Final amplitude of the neurostimulation in some cases is not predicted by ohm’s law and a careful review of the neurostimulation parameters is always recommended. We highlight that the patient who showed clinical worsening had kinetraMedtronic electrodes and extensions. Therefore, in this case the main cause might have been the incompatibility of the adapters and not the switch from constant-voltage to constant current.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/can-the-ohms-law-predict-the-amplitude-of-neurostimulation-when-adapting-systems-in-deep-brain-stimulation/