Unstable impedance of a single electrode contact resulting in loss of DBS therapy-a case report.

Open and short circuits of electrode contacts are important technical dysfunctions of DBS. Here, we report on another type of dysfunction restricted to a single electrode contact: impedance instability within regular absolute values. After 9-year subthalamic DBS, a Parkinson patient developed unilateral motor symptoms and intermittent dysaesthesia due to impedance instability of the active contact.

DBS Electrodes With Single Disconnected Contacts: Long-Term Observation and Implications for the Management.

Objectives: To evaluate the long-term course of quadripolar DBS electrodes with disconnected single contacts that cannot be used for DBS.

Materials And Methods: Quadripolar electrodes with open circuits of single contacts or monopolar impedances >6500 Ω were identified from a cohort of 2082 electrodes from 1044 patients with variable movement disorders. The long-term course was analyzed from follow-up data.