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Introduction: For deep brain stimulation (DBS) surgery of the subthalamic nucleus (STN) in Parkinson’s disease (PD), many centers employ visualization of the nucleus on magnetic resonance imaging (MRI), intraoperative microelectrode recordings (MER), and test stimulation in awake patients. The value of these steps is a subject for ongoing debate. In the current study, we determined the relative contribution of MRI targeting, multitrack MER, and awake test stimulation in final lead placement during STN DBS surgery for PD. Methods: Data on PD patients undergoing MRI-targeted STN DBS surgery with three-channel MER and awake test stimulation between February 2010 and January 2014 were analyzed to determine in which MER trajectory final leads were implanted and why this tract was chosen. Results: Seventy-six patients underwent implantation of 146 DBS leads. In 92% of the STN, the final leads were implanted in one of the three planned channels. In 6%, additional channels were needed. In 2%, surgery was aborted before final lead implantation due to anxiety or fatigue. The final leads were implanted in the channels with the longest STN MER signal trajectory in 60% of the STN (38% of the bilaterally implanted patients). This was the central channel containing the MRI target in 39% of the STN (18% bilaterally). The most frequently noted reasons why another channel than the central channel was chosen for final lead placement were (1) a lower threshold for side effects (54%) and (2) no or a too short trajectory of the STN MER signal (40%) in the central channel. The latter reason correlated with larger 2D (x and y) errors in our stereotactic method. Conclusions: STN DBS leads were often not implanted in the MRI-planned trajectory or in the trajectory with the longest STN MER signal. Thresholds for side effects during awake test stimulation were decisive for final target selection in the majority of patients.

Background: In deep brain stimulation of the subthalamic nucleus (STN-DBS) for Parkinson’s Disease (PD), often microelectrode recordings (MER) are used for STN identification. However, for advanced target identification of the sensorimotor STN, it may be relevant to use local field potential (LFP) recordings. Then, it is important to assure that the measured oscillations are coming from the close proximity of the electrode. New method: Through multiple simultaneous recordings of LFP and neuronal spiking, we investigated the temporal relationship between local neuronal spiking and more global LFP. We analyzed the local oscillations in the LFP by calculating power only over specific frequencies that show a significant coherence between LFP and neuronal spiking. Using this ‘coherence method’, we investigated how well measurements in the sensorimotor STN could be discriminated from measurements elsewhere in the STN. Results/comparison with existing methods: The ‘sensorimotor power index’ (SMPI) of beta frequencies, representing the ability to discriminate sensorimotor STN measurements based on the beta power, was significantly larger using the ‘coherence method’ for LFP spectral analysis compared to other methods where either the complete LFP beta spectrum or only the prominent peaks in the LFP beta spectrum were used to calculate beta power. Conclusions: The results suggest that due to volume conduction of beta frequency oscillations, proper localization of the sensorimotor STN with only LFP recordings is difficult. However, combining recordings of LFP and neuronal spiking and calculating beta power over the coherent parts of the LFP spectrum can be beneficial in discriminating the sensorimotor STN.

Question STN-DBS could be improved by specifically targeting the dorsolateral part of the STN. However, the correspondence between the location of the STN on T2 MRI images used for targeting and the location of the neurophysiological STN remains unclear. In this study, we compared the STN borders on T2 MRI images with the STN borders identified by microelectrode recordings (MER), measured during DBS surgery. We study the differences between MER-based STN and MRI-based STN in 1.5 T, 3.0 T and 7.0 T images. Methods An atlas-based 3D model of the STN was automatically fitted onto the exact stereotactic locations of the MER points using their classifications as inside or outside the STN. The agreement between STN models and the MRI images of the STN was evaluated by an experienced neurosurgeon. T2 MRI images of 1.5 T (n = 14), 3.0 T (n = 10) and 7.0 T (n = 8) scans were compared. Results The dorsal border of the STN was identified more dorsal on the MRI than it was by MER. This was significant in the 3.0 T and 7.0 T images, with similar mismatch patterns decreasing towards the medial side of the dorsal border ( Fig. 1 ). The lateral border was identified significantly more medial on the MRI than it was by MER, for both 1.5 T and 3.0 T images. The STN borders on 7.0 T images showed no significant differences with MER ( Fig. 2 ). Conclusions MER helps to refine the delineation of the dorsal and lateral border of the STN in MRI-based targeting. Increasing MRI field strength to 7.0 T may improve identification of the lateral, but not the dorsal STN border.

Background Multi-directional electrodes in STN-DBS give the possibility to steer the high frequency current into the direction for clinical improvement and moreover recording of multi-array local field potential recordings (LFPs) give the possibility to determine the spatiotemporal distribution of oscillatory power across the STN that is related to the symptomatology in PD patients. Ultimately this information can be used as a feedback to optimize the stimulation parameters. Methods Eight PD patients were included in the study. After micro-electrode recording (MER), to determine the boundaries of the STN, temporarily a prototype of a new 32-contact DBS lead was inserted during the DBS procedure. Different modes of current steering were employed to improve motor symptoms and patients were scored on beneficial and adverse effects. Prior to and immediately after stimulation the distribution of spectral power was recorded by LFPs and spatiotemporal changes were evaluated with Fourier analysis. Results Thresholds of the effects of spherical stimulation were comparable to thresholds of stimulation through the conventional electrode at the same location in 89% of the cases. In eight of fourteen side effects, steering stimulation current increased the threshold for side effects by ⩾ 1 mA compared to spherical stimulation. The size of the therapeutic window could be widened in patient 6, 7 and 8 by steering stimulation in the posterior, posterior and anterior direction, respectively. LFP recordings prior to stimulation yielded the boundaries of the STN by showing increased spectral power particularly in the 13–40 Hz range. Recordings across all directions showed distinct spatiotemporal patterns of neuronal activity, which were related to the pattern of stimulation and the PD symptoms of the patient. Conclusions With a new DBS lead it is possible to steer stimulation current in STN-DBS such that it leads to a larger therapeutic window than with conventional spherical stimulation. Simultaneous LFP recordings across the entire STN provide spatial information about the location of the STN and its disease-related electrical activity. This may potentially be of benefit in predicting how to steer the current towards the sensorimotor part, while avoiding adverse effects.

Introduction Le tiotropium Respimat ® , en une prise par jour (TioR), traitement bronchodilatateur additionnel a une dose moyenne de CSI a demontre son efficacite chez les patients adultes avec un asthme modere. L’objectif de cette analyse est d’etudier chez le patient asthmatique si l’efficacite de TioR, en traitement additionnel d’un CSI, est differente selon l’utilisation ou non des antileucotrienes (LTRA) en traitement initial. Methodes Deux etudes jumelles, de phase III, randomisees, en double aveugle, en 4 groupes paralleles recevant soit TioR 5 μg ou 2,5 μg, une fois par jour, ou du salmeterol HFA-MDI 50 μg deux fois par jour ou un placebo, en traitement additionnel a une dose moyenne de CSI (400–800 μg budesonide ou equivalent), chez des patients atteints d’asthme modere. Les co-criteres principaux etaient les VEMS au pic et residuel (difference vs inclusion) a la semaine 24 ; des analyses post-hoc etaient realisees selon l’utilisation ou non des LTRA a l’inclusion. Resultats Deux milles cent patients etaient randomises : 183 (8,7 %) recevaient un LTRA a l’inclusion. Les caracteristiques demographiques entre les groupes recevant ou non des LTRA etaient comparables : âge moyen : respectivement, 43,9 ± 13,4 et 43,1 ± 12,8 annees, IMC : respectivement, 27,5 ± 6,6 et 26,8 ± 6,2 kg/m 2 , VEMS( %) a l’inclusion : respectivement, 75,19 ± 12,03 et 75,04 ± 11,46. Compare au placebo, TioR ameliorait la fonction pulmonaire independamment de l’utilisation ou non des LTRA ( Tableau 1 ) Conclusion Tiotropium Respimat ® , une fois par jour, en traitement additionnel a une dose moyenne de CSI etait efficace chez les adultes souffrant d’asthme moderee, independamment de l’utilisation des LTRA.

Computer simulation with a model of the saccadic burst generator, proposed by C. A. Scudder (1988), demonstrated that metrics of saccades as well as their velocity characteristics can be altered without changing the characteristics of the burst generator itself. The model could be used to explain impairment of saccadic eye movements in, for instance, Parkinson's disease (PD), since in this disorder at brainstem level pontine structures, where the burst generator is located, are unaffected. Comparison of saccades in PD patients with computer simulations showed that the model provided reasonable explanation for the observed reduction in maximum saccade velocity, but is not appropriate to explain hypometria of saccades.

Clinitron beds, often used to prevent decubitus ulcers, may cause an EEG artefact by static electricity. The best way to prevent this artefact is to turn off the bed during EEG registrations.