Deep brain stimulation inactivity can produce unexpected high electrode impedances when reactivated, leading to a false conclusion of wire fracture

Two months after bilateral DBS surgery in a patient with PD, the stimulator had to be removed temporarily due to an infection. After successful antibiotic treatment, a new stimulator and extension wire were reimplanted 2 months later. Intraoloerative testing of the replacement device yielded unusually high electrode impedances and low currents on one lead across all four contacts. Since the results did not change on repeated measurements, a lead fracture was suspected. Visual inspection of the exposed hardware, however, did not reveal any obvious defects. It was then decided to activate the lead for a prolonged time with significant currents. Subsequent impedance measurements yielded normal values and after the patient awoke from anesthesia, good symptom control was again achieved. It is advisable if a lead fracture is suspected under similar circumstances to 'condition' the electrode with high currents. Failure to do so could lead to a false conclusion of a lead fracture and unnecessary stereotactic surgery to replace it. Copyright (C) 2005 S. Karger AG, Basel.