Abnormal local field potentials precede clinical complications after DBS surgery for Parkinson's disease: A case report

Although deep brain stimulation (DBS) surgery rarely leads to complications, when it does they can be serious (Fenoy and Simpson, 2014). In a recent study about DBS surgery complications in movement disorders, postoperative imaging demonstrated that asymptomatic intracerebral hemorrhage (ICH) occurs in 0.5% of patients, asymptomatic intraventricular hemorrhage in 3.4%, symptomatic ICH in 1.1%, and ischemic infarction in 0.4% (Fenoy and Simpson, 2014). Local field potentials (LFPs) are oscillatory bioelectrical signals arising from large neuronal ensembles around an electrode inserted into the central nervous system. LFP originating from deep human brain structures can be recorded through the electrodes used for DBS in various pathological conditions. For instance, in Parkinson’s disease (PD) LFP beta activity (13–30 Hz) is typically recorded in the off-medication state and when DBS is turned off. Levodopa treatment and DBS (Giannicola et al., 2010) both suppress beta activity and the degree of suppression correlates with motor improvement. Though recordings from the subthalamic nucleus (STN) are mainly used for experimental purposes they could be useful for monitoring DBS surgery: Chen and colleagues (Chen et al., 2006) showed that intra-operative LFP recordings help identifying the STN by disclosing specific beta activity. We report the case of a patient in whom LFP recordings disclosed abnormal STN activity before complications related to DBS became clinically and neuroradiologically evident.