Hardware complications in deep brain stimulation: Electrode impedance and loss of clinical benefit

Background: Deep brain stimulation (DBS) is an effective treatment in patients with movement disorders. Successful outcomes are correlated with patient selection, accurate placement of the electrodes in their surgical target and optimal programming of patients. The loss of clinical efficacy after successful treatment may be related to hardware complications. Objectives: We studied the causes of loss of stimulation efficacy in patients with stable antiparkinsonian benefit after DBS. Results: Seven out of 110 (6.3%) patients surgically treated with DBS showed a loss of clinical efficacy, and were included in the study. Five cases had subacute clinical worsening and two sudden deterioration. All of them had an impedance increment (> 4000 Omega) with the active contacts. Further reprogramming was attempted in all the cases using the undamaged contacts. However, five patients had incomplete clinical control and were reoperated with an electrode replacement. X-rays provided information in all cases except one showing the disruption or rupture of electrode. Conclusions: It is important to identify this hardware problem in view of the growing number of patients receiving this therapy. A protocol for patients with loss of stimulation efficacy and electrode impedance increment needs to be created in clinical visits in order to detect the failed stimulation mechanism. (c) 2012 Elsevier Ltd. All rights reserved.