Objective: We aimed to evaluate the impedance of patients on their best ON/worst OFFs with levodopa, assuming that the level of dopamine at electrode’s vicinity is high or low, respectively.

Background: Impedance (effective resistance to alternating current) is a variable parameter. In vivo studies showed that the presence of dopamine decreases impedance of DBS electrode.

Method: 24 patient with PD treated with STN DBS consented to join. Medical treatment and DBS configuration were not changed at least for three months. Impedance is assessed after withdrawal of dopaminergic medication for at least 12 hours and after taking levodopa when patients tell that are at their best ON (approximately one hour later).

Results: There was no significant difference between therapy impedances of ON medication and medication-free groups [table 1] . Also 158 of 160 contact electrode impedances didn’t differ significantly.

Conclusion: Levodopa therapy doesn’t effect either therapy and electrode impedance. This means that impedance can be measured regardless of whether the patient is drug-ON or OFF state, and presumed presence of high levels of dopamine does not effect impedance values in humans.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/impedance-doesnt-change-with-levodopa-treatment/