BACKGROUND In the United States, the most commonly used surgical treatment for patients with Parkinson’s disease is the implantation of deep brain stimulation (DBS) electrodes within the subthalamic nucleus. However, DBS device programming remains difficult and is a possible source of decreased efficacy. OBJECTIVE We investigated the relationship between local field potential (LFP) activities in the subthalamic nucleus and the therapeutic response to programming. METHODS We recorded LFPs with macroelectrodes placed unilaterally for DBS in 4 PD patients, 3 weeks after implantation, before the start of log-term DBS. Power-frequency spectra were calculated for each of 7 possible electrode contacts or contact pairs, over multiple 5- to 10-minute quiet waking epochs and over 30-second epochs during hand movements. Subsequently, DBS devices were programmed, with testing to determine which electrode contacts or contact pairs demonstrated optimal therapeutic efficacy. RESULTS For each patient, the contact pair found to provide optimal efficacy was associated with the highest energy in the β (13–32 Hz) and γ (48–220 Hz) bands during postoperative LFP recordings at rest and during hand movements. Activities in other frequency bands did not show significant correlations between LFP power and optimal electrode contacts. CONCLUSION Postoperative subband analysis of LFP recordings in β and γ frequency ranges may be used to select optimal electrode contacts. These results indicate that LFP recordings from implanted DBS electrodes can provide important clues to guide the optimization of DBS therapy in individual patients.

Although motor subtypes of Parkinson's disease (PD), such as tremor dominant (TD) and postural instability and gait difficulty (PIGD), have been defined based on symptoms since the mid-1990s, no underlying neural correlates of these clinical subtypes have yet been identified. Very limited data exist regarding the electrophysiological abnormalities within the subthalamic nucleus (STN) that likely accompany the symptom severity or the phenotype of PD. Here, we show that activity in subbands of local field potentials (LFPs) recorded with multiple microelectrodes from subterritories of STN provide distinguishing neurophysiological information about the motor subtypes of PD. We studied 24 patients with PD and found distinct patterns between TD ( = 13) and PIGD ( = 11) groups in high-frequency oscillations (HFOs) and their nonlinear interactions with beta band in the superior and inferior regions of the STN. Particularly, in the superior region of STN, the power of the slow HFO (sHFO) (200-260 Hz) and the coupling of its amplitude with beta-band phase were significantly stronger in the TD group. The inferior region of STN exhibited fast HFOs (fHFOs) (260-450 Hz), which have a significantly higher center frequency in the PIGD group. The cross-frequency coupling between fHFOs and beta band in the inferior region of STN was significantly stronger in the PIGD group. Our results indicate that the spatiospectral dynamics of STN-LFPs can be used as an objective method to distinguish these two motor subtypes of PD. These observations might lead to the development of sensing and stimulation strategies targeting the subterritories of STN for the personalization of deep-brain stimulation (DBS).

Magnetic resonance imaging (MRI) of patients with implanted deep brain stimulation (DBS) devices poses a challenge for healthcare providers. As a consequence of safety concerns about magnetic field interactions with the device, induced electrical currents and thermal damage due to radiofrequency heating, a number of stringent guidelines have been proposed by the device manufacturer. Very few detailed investigations of these safety issues have been published to date, and the stringent manufacturer guidelines have gone unchallenged, leading some hospitals and imaging centers around the world to ban or restrict the use of MRI in DBS patients. The purpose of this review is to stimulate research towards defining appropriate guidelines for the use of MRI in patients with DBS. Additionally, this review is intended to help healthcare providers and researchers make sound clinical judgments about the use of MRI in the setting of implanted DBS devices.

Purpose: To study the effect of the extracranial portion of a deep brain stimulation (DBS) lead on radiofrequency (RF) heating with a transmit and receive 9.4 Tesla head coil. Materials and Methods:The RF heating was studied in four excised porcine heads (mean animal head weight ¼ 5.46 6 0.14 kg) for each of the following two extracranial DBS lead orientations: one, parallel to the coil axial direction; two, perpendicular to the coil axial direction (i.e., azimuthal). Temperatures were measured using fluoroptic probes at four locations: one, scalp; two, near the second DBS lead electrodebrain contact; three, near the distal tip of the DBS lead; and four, air surrounding the head. A continuous wave RF power was delivered to each head for 15 min using the coil. Net, delivered RF power was measured at the coil (mean whole head average specific absorption rate ¼ 2.94 6 0.08 W/kg).Results: RF heating was significantly reduced when the extracranial DBS lead was placed in the axial direction (temperature change ¼ 0-5 C) compared with the azimuthal direction (temperature change ¼ 1-27 C).Conclusion: Development of protocols seems feasible to keep RF heating near DBS electrodes clinically safe during ultra-high field head imaging.

Parkinson's disease (PD) is a degenerative brain disorder accompanied by the loss of dopaminergic neurons and the presence of motor and non-motor symptoms. We performed a cross-sectional, questionnaire-based analysis of impulsive behavior in our PD clinic population to assess prevalence and associated characteristics. We found a higher prevalence of impulsive behavior (29.7%) than previously reported, and found multiple, concurrent impulsive behaviors in 26% of subjects reporting impulsive behavior. Our findings contribute to the growing awareness of impulsive behavior in PD, and support the need for longitudinal studies to assess changes in impulsive behaviors in Parkinson's patients.