β-band peak in local field potentials as a marker of clinical improvement in Parkinson's Disease after Deep Brain Stimulation

Although locating the stimulation contact in Deep Brain Stimulation (DBS) requires a sub-mm-precision, it remains a trial-and-error, patient-specific procedure that is usually the main cause of post-operational side-effects. In this work, we used microelectrode recordings from Parkinson's disease (PD) patients, acquired at the Neurosurgery Clinic, Evangelismos Hospital, Athens, Greece, to relate the β-band peak, a known neurophysiological signature of the sensorimotor pathways with the clinical outcome of DBS, as assessed by an expert neurologist after a follow-up of at least 1 year. By combining recordings from 5 microelectrodes, we estimated a summed β-band amplitude peak, per recording depth. We suggest that the maximum aggregate β-band peak is related to the stimulation target. We verified our method in 6 patients that responded well in a bilateral DBS treatment (average increase of Unified Parkinson's Disease Rating scale by 32.6 ± 5.4). In 7 out of 12 hemispheres, the distance between the stimulation depth and that of the maximum β-band peak was 0 and for the rest cases that distance was smaller than 2 mm which is a typical effective radius of a stimulation point. Our method needs to be further supported by data acquired from patients with good and poor clinical responses after DBS. © Springer International Publishing Switzerland 2014.