Long-Term Stability of Short Circuits in Deep Brain Stimulation

Objectives: To evaluate the long-term course of DBS electrodes with short-circuited contacts. Materials and Methods: Electrodes with bipolar impedances below 150 Omega were identified from a cohort of 1044 patients with 2082 electrodes for variable movement disorders. The long-term course was analyzed from follow-up data. Results: Short circuits were found in 62 electrodes (3.0%) from 60 patients (5.7%). They were restricted to two contacts in 57 electrodes (91.9%) and included more than two contacts in five electrodes. Onset was related to surgery (implantation, impulse generator replacements, or other surgical revisions) in 42 electrodes (67.7%). The onset was undetermined in 11 electrodes. In eight electrodes (12.9%) with previously normal impedances, the short circuit occurred spontaneously during long-term DBS and in one electrode after a fall. Repeated impedance checks at follow-ups of >= 3 months were available in 41 electrodes with short circuits. Twenty-six electrodes (63.4%) showed stable low impedances during observation up to nine years and two months (median 29 months). In four electrodes low impedances were stable until surgical revisions. In eight electrodes (19.5%) with observation up to nine years and seven months (median 54 months), short circuits were only detected intermittently but remained restricted to two contacts. In three electrodes (7.3%) intermittent short circuits between more than two contacts were found during long-term DBS. Conclusions: An increasing cumulative incidence demonstrates the clinical importance of short circuits. In the majority of electrodes, short circuits are restricted and remain restricted to two contacts during long-term stimulation.