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 Ω 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.