Implantation Of Deep Brain Stimulation Electrodes Research Articles

Metal Artifact Reduction in Computed Tomography After Deep Brain Stimulation Electrode Placement Using Iterative Reconstructions.

Diagnostic accuracy of intraoperative computed tomography (CT) after deep brain stimulation (DBS) electrode placement is limited due to artifacts induced by the metallic hardware, which can potentially mask intracranial postoperative complications. Different metal artifact reduction (MAR) techniques have been introduced to reduce artifacts from metal hardware in CT. The purpose of this study was to assess the impact of a novel iterative MAR technique on image quality and diagnostic performance in the follow-up of patients with DBS electrode implementation surgery. Seventeen patients who had received routine intraoperative CT of the head after implantation of DBS electrodes between March 2015 and June 2015 were retrospectively included. Raw data of all patients were reconstructed with standard weighted filtered back projection (WFBP) and additionally with a novel iterative MAR algorithm. We quantified frequencies of density changes to assess quantitative artifact reduction. For evaluation of qualitative image quality, the visibility of numerous cerebral anatomic landmarks and the detectability of intracranial electrodes were scored according to a 4-point scale. Furthermore, artifact strength overall and adjacent to the electrodes was rated. Our results of quantitative artifact reduction showed that images reconstructed with iterative MAR (iMAR) contained significantly lower metal artifacts (overall low frequency values, 1608.6 ± 545.5; range, 375.5-3417.2) compared with the WFBP (overall low frequency values, 4487.3 ± 875.4; range, 2218.3-5783.5) reconstructed images (P < 0.004). Qualitative image analysis showed a significantly improved image quality for iMAR (overall anatomical landmarks, 2.49 ± 0.15; median, 3; range, 0-3; overall electrode characteristics, 2.35 ± 0.16; median, 2; range, 0-3; artifact characteristics, 2.16 ± 0.08; median, 2.5; range, 0-3) compared with WFBP (overall anatomical landmarks, 1.21 ± 0.64; median, 1; range, 0-3; overall electrode characteristics, 0.74 ± 0.37; median, 1; range, 0-2; artifact characteristics, 0.51 ± 0.15; median, 0.5; range, 0-2; P < 0.002). Reconstructions of cranial CT images with the novel iMAR algorithm in patients after DBS implantation allows an efficient reduction of metal artifacts near DBS electrodes compared with WFBP reconstructions. We demonstrated an improvement of quantitative and qualitative image quality of iMAR compared with WFBP in patients with DBS electrodes.

Prevalent placement error of deep brain stimulation electrode in movement disorders (technical considerations).

Deep brain stimulation is an effective and safe technique. Displacement of the electrode relative to the optimal stimulation site can lead to insufficient effect and sometimes to the need of operative electrode re-position. This study was aimed to analyse targeting accuracy of deep brain stimulation electrode implantation to subthalamic nucleus (STN) and globus pallidus internus (Gpi). It detected possible causes of inaccuracy and prevalent shift to certain direction. Targeting accuracy was analysed in 47 patients with Parkinson´s disease (PD) and 11 patients with dystonia with bilateral implantation of deep brain stimulation electrodes between years 2009 and 2016. A shift of electrode to prevalent direction was observed on the left side to medial and posterior and on the right side to lateral direction. Greater shift was observed on the left side and in a higher angulation of trajectory laterally. Movement of the electrode, because of its traction in anchoring device, was identified as a possible factor for prevalent electrode shift. Calibration of stereotactic coordinates to correct prevalent shift was used. Targeting inaccuracy is the result of accumulation of errors in individual steps of electrode implantation. Direction of the shift can be random or it can be toward a prevalent direction. A correction of prevalent error can prevent a suboptimal electrode placement (Tab. 3, Fig. 11, Ref. 29).

Diffusion Tensor Imaging-Based Thalamic Segmentation in Deep Brain Stimulation for Chronic Pain Conditions

Background/Aims: Thalamic deep brain stimulation (DBS) for the treatment of medically refractory pain has largely been abandoned on account of its inconsistent and oftentimes poor efficacy. Our aim here was to use diffusion tensor imaging (DTI)-based segmentation to assess the internal thalamic nuclei of patients who have undergone thalamic DBS for intractable pain and retrospectively correlate lead position with clinical outcome. Methods: DTI-based segmentation was performed on 5 patients who underwent sensory thalamus DBS for chronic pain. Postoperative computed tomography images obtained for electrode placement were fused with preoperative magnetic resonance images that had undergone DTI-based thalamic segmentation. Sensory thalamus maps of 4 patients were analyzed for lead positioning and interpatient variability. Results: Four patients who experienced significant pain relief following DBS demonstrated contact positions within the DTI-determined sensory thalamus or in its vicinity, whereas 1 patient who did not respond to stimulation did not. Only 4 voxels (2%) within the sensory thalamus were mutually shared among patients; 108 voxels (58%) were uniquely represented. Conclusions: DTI-based segmentation of the thalamus can be used to confirm thalamic lead placement relative to the sensory thalamus and may serve as a useful tool to guide thalamic DBS electrode implantation in the future.

EP 60. Bicycling suppresses beta power more strongly than walking in the subthalamic nucleus of Parkinsonian patients

Introduction Walking abilities are severely affected in patients suffering from Freezing of Gait (FOG), a common phenomenon in advanced Parkinson’s disease (PD). Despite the high occurrence of the symptom in the progression of the disease, little is known about the underlying mechanisms. Remarkably, it was recently reported that patients with FOG are still able to ride a bike ( [Snijders et al., 2011] , [Snijders et al., 2012] ). While similar brain networks are involved in walking and bicycling ( [Fukuyama et al., 1997] , [Christensen et al., 2002] ), it is not understood why both types of movement are differently affected in patients with FOG. Therefore, this study aimed to investigate neural oscillations underlying bicycling and walking in PD patients. Patients and methods Seven PD patients (mean age 55.4±6.3 y) clinically selected for bilateral deep brain stimulation (DBS) therapy were included in the study. Using a portable EEG system (Porti, TMSi, Enschede, The Netherlands), local field potentials from the subthalamic nucleus (STN) were recorded using externalised leads the day after implantation of DBS electrodes. Patients were recorded while OFF any dopaminergic medication during unconstrained bicycling and walking on a stationary bicycle. The paradigm consisted of a baseline rest period, continuous movement, and an alternating sequence of rest and movement, i.e. bicycling or walking, in order to study both movement initiation and movement termination. For each STN the bipolar channel with the highest baseline beta peak power was selected for further analyses. Three of 14 STNs had to be excluded because of movement artefact contamination and a broken externalised lead in one patient. Differences were determined using cluster-based permutation tests as implemented in the FieldTrip analysis toolbox ( Oostenveld et al., 2011 ). Results Movement initiation was accompanied by power decreases in the alpha–beta range (8–35 Hz) in bicycling and walking. Contrasting both conditions revealed a stronger beta power decrease in bicycling (p 0.05). Conclusions Our finding that bicycling leads to a stronger power decrease in the beta band than walking is particularly interesting as Parkinson’s disease is generally associated with abnormally increased beta band activity in the corticobasal ganglia loop ( Oswal et al., 2013 ). The difference between oscillatory activity underlying bicycling and walking was specific to beta power suppression during movement, whereas beta rebound after movement termination was equally strong. In this sense, bicycling seems to promote the suppression of pathological oscillations in the basal ganglia, as opposed to walking. This may be due to the more continuous movement in bicycling with both legs being pushed forward permanently. In walking, stance and swing phases alternate. Therefore, one may speculate that bicycling may be less hampered in FOG because the more continuous nature of this movement promotes beta suppression and thus, facilitates movement.

EP 63. Spectral analysis and visualization of multi-unit activity in subthalamic nucleus in Parkinson’s as a tool for automated electrophysiological classification of basal ganglia structures during deep brain stimulation procedures

Introduction In deep brain stimulation (DBS) of the subthalamic nucleus (STN) intraoperative microelectrode recordings (MER) are a well-established method for electrophysiological stereotactic target identification. Despite the main electrophysiological properties of STN are already well described ( [Cagnan et al., 2011] , [Seifried et al., 2012] ), mapping of STN rely on visual and acoustic inspection of raw recordings of MER trajectories. In this study we analyzed spectral decomposition and spike train patterns retrospectively of MER in STN-DBS to proposing a simple and reliable electrophysiological classification system. Secondly we suggest visualization techniques to present electrophysiological results in a user-friendly way. Patients and methods We analyzed MER in 7 patients with bilateral STN-DBS including 26 MER trajectories retrospectively. All recordings were carried out on multiple trajectories 10 mm prior and 4–5 mm below MR-tomographic STN target along planed DBS lead trajectory. Data was recorded intraoperative by Medtronic Leadpoint system using sharp microTargeting electrodes (FHC, USA). Offline Multi-Unit activity analysis was realized with Fieldtrip-Toolbox and Matlab, Mathworks. Statistical analysis of power spectral density, noise level and spike interstimulus interval were obtained through non-parametric student’s t-test. In purpose of visualization we integrated the stereotactic surgical plan to the electrophysiological results. Results Spectral density analysis showed a strong increase in frequency bands of 300–1000 Hz within STN borders. Spike train patterns within STN were heterogeneously and differed in firing rate and interstimulus interval to the key anatomical structures, thalamus and substantia nigra. Conclusion Through combination of spectral density analysis and spike train analysis we propose a simple and reliable MER signal classification method, which can be used for automated electrophysiological mapping of STN. Three-dimensional visualization of mapping results can provide help for decision of final DBS electrode implantation site.

Processing of emotional stimuli is reflected by modulations of beta band activity in the subgenual anterior cingulate cortex in patients with treatment resistant depression.

Deep brain stimulation (DBS) of the subgenual anterior cingulate cortex (sgACC) has emerged as a new therapeutic option in patients with treatment resistant depression (TRD). At the same time, DBS offers a unique opportunity as an innovative research tool to study brain function in vivo Indirect measures of brain function such as positron-emission-tomography imaging findings have revealed a hypermetabolism in the sgACC area in patients with TRD that normalizes in parallel with treatment response to DBS. We used direct intracranial recordings via implanted DBS electrodes to study the neuronal oscillatory activity in the sgACC area during a picture viewing task including emotional and neutral stimuli in eight patients with TRD who underwent DBS.We found a stimulus-induced decrease in beta-band and increase in gamma-band activity, with a main effect of valence for event-related desynchronisation in the beta-frequency range (14-30 Hz). Unpleasant stimuli induced the strongest and most sustained beta-power decrease. The degree of beta-band modulation upon emotional stimuli correlated with the patients' rating of stimulus valence. Our findings confirm the involvement of the sgACC area in emotional processing that was more enhanced for unpleasant stimuli. Moreover, stimulus evaluation may be encoded by modulations of beta-band activity.

Hippocampal deep brain stimulation in nonlesional refractory mesial temporal lobe epilepsy

PurposeTo evaluate the efficacy of chronic continuous hippocampal deep brain stimulation (DBS) in nonlesional refractory mesial temporal lobe epilepsy. MethodsThree adult patients with medically intractable epilepsy treated with hippocampal DBS were studied. Two patients underwent invasive recordings with depth stereo-electroencephalography (SEEG) electrodes to localize ictal onset zone prior to implantation of DBS electrodes. All the patients with no lesion in brain magnetic resonance imaging (MRI) scan received bilateral implantation of DBS electrodes. Chronic continuous high-frequency hippocampal stimulation was applied during treatment. The number of seizures in each patient before and after stimulation was compared. ResultsLong-term hippocampal stimulation produced a median reduction in seizure frequency of 93%. Two out of these patients received unilateral activation of the electrodes and experienced a 95% and 92% reduction in seizure frequency after hippocampal DBS respectively. The last patient had bilateral electrode activation and had a seizure-frequency reduction of 91%. None of the patients had neuropsychological deterioration and showed side effects. Generalized tonic–clonic seizures disappeared completely after hippocampal DBS. ConclusionsChronic continuous hippocampal DBS demonstrated a potential efficiency and safety in nonlesional refractory mesial temporal lobe epilepsy and might represent an effective therapeutic option for these patients.

Effect of Cranial Window Diameter During Deep Brain Stimulation Surgery on Volume of Pneumocephalus.

Successful deep brain stimulation (DBS) surgery necessitates high accuracy in targeting specific intracranial nuclei. Brain shift due to pneumocephalus can contribute to decreased accuracy. Larger burr holes and dural openings may increase pneumocephalus volume due to a greater degree of communication between the subdural space and extracranial air. The aim of this study is to determine if there is a statistically and clinically significant difference in postoperative pneumocephalus volume related to burr hole and durotomy size. DBS electrodes were surgically implanted through either large (14 mm) burr holes or small (4 mm) twist drill holes. Immediate postoperative computerized tomography (CT) scans of 165 electrode implantations in 85 patients from 2010 to 2013 were retrospectively analyzed. Student's t-test and Mann-Whitney U-test were employed with a threshold of significance set at p ≤ 0.05. No significant difference in pneumocephalus was identified between patients who had implantation of DBS electrodes through 4 mm twist drill holes (N = 71 hemispheres, 12.84 ± 9.79 cm(3) ) and those with large 14 mm burr holes (N = 87, 11.70 ± 7.46 cm(3) , p = 0.42). Volume of pneumocephalus did not correlate with duration of surgery or patient age. The groups did not differ significantly with respect to other aspects of surgical implantation technique or surgical duration. While identifying factors that may reduce pneumocephalus volume may be critical to improving stereotactic accuracy and targeting, the current results suggest that burr hole size may not alter the degree of brain shift.

V40. Deep brain recordings using an implanted pulse generator in Parkinson’s disease

Introduction Deep brain stimulation (DBS) in the subthalamic nucleus (STN) for Parkinson’s disease (PD) has been shown to be a safe and effective treatment. Recent studies suggest that oscillatory beta activity could be used as a biomarker in patients with PD for subthalamic closed-loop stimulation leading to improved clinical benefit and reduced energy consumption. The aim of the present study was to evaluate the feasibility of local field potential (LFP) recordings for closed-loop stimulation using a new generation of implantable stimulators that also can record LFPs. Materials and methods Eight patients with PD (2 female, mean age 66.1 ± [SEM] 1.5 years; disease duration 10.5 ± 1.4 years) who underwent bilateral implantation of DBS electrodes in the STN were included in the study. LFP recordings were conducted at rest ON and OFF subthalamic high frequency stimulation (140 Hz) via DBS electrodes using the new stimulator device (bipolar recordings from contact pair 0–2, monopolar stimulation at contact 1). FFT based power spectra were calculated ON and OFF DBS, normalized to total power and compared between conditions. Results We recorded subthalamic oscillatory activity from 15 out of 16 DBS electrodes using the stimulator’s sensing function. We found discrete peaks in the beta band in 12 out of 15 electrodes (mean peak frequency 17 Hz). A significant reduction in averaged beta band power (13–30 Hz) of 14% was found ON compared to OFF DBS condition ( p = 0.002). No difference was found in the alpha band (7–13 Hz; p > 0.05). Direct comparison of beta peak frequency aligned power spectra across the group revealed a significant DBS related beta power reduction in a frequency range from −1.4 Hz to +5.8 Hz ( p ⩽ 0.03, FWE corrected) surrounding the individual peaks. Discussion We demonstrate for the first time recordings of human deep brain activity from a new generation of fully implantable pulse generators with sensing function. Discrete peaks in beta activity were obtained from the subthalamic area from 12 out of 15 electrodes when patients were OFF medication, moreover the new device could identify a significant suppression of beta band activity during DBS. The present results give further evidence for beta band activity being a useful biomarker in PD patients that can be followed with implantable systems.

A comparison of two surgical approaches in functional neurosurgery: individualized versus conventional stereotactic frames

Object: The individualized Starfix® miniframe belongs to a new generation of stereotactic systems enabling high-precision electrode placement with considerably better time-efficiency in deep brain stimulation (DBS). We evaluated the usability and reliability of this novel technique in patients with idiopathic Parkinson’s disease (IPD) and compared surgical and clinical results with those obtained in a historical group in which a conventional stereotactic frame was employed. Methods: Sixty patients underwent surgery for implantation of DBS electrodes in the subthalamic nucleus. In 31 of them (group I) a conventional Zamorano-Dujovny frame was used and in 29 of them (group II) a Starfix® miniframe was used. Image fusion of preoperatively acquired 3D T1w and T2w 1.5 T MR-image series was used for the targeting procedure. Placement of the test electrodes and permanent electrodes corresponded to standard functional neurosurgery and included microelectrode recording and macrostimulation. Clinical (L-Dopa equivalent dose, United Parkinson's disease rating scale part III) and time for surgical electrode implantation were evaluated postoperatively in a 3-, 6- and 12-month follow-up. Results: Twelve months postoperatively, L-Dopa dose was significantly reduced from 685.19 to 205.88 mg/day and from 757.92 to 314.42 mg/day in groups I and II, respectively. A comparable reduction of the LED could be observed 1 year after surgery. Motor function has improved in a significant and identical manner with 59% (group I) and 61% (group II). Besides clinical effects by stimulation therapy there was a significantly reduced surgery time required for electrode implantation using the Starfix® miniframe (group I: 234.1 min, group II: 173.6 min; p < 0.001). Conclusions: Individualized miniframes such as the Starfix® miniframe allow implantation of DBS electrodes in IPD that is equally effective as conventional systems. The time efficiency achieved in surgery using of the Starfix® system helps to minimize patients' discomfort during DBS surgery.

Improved stereotactic procedure enhances the accuracy of deep brain stimulation electrode implantation in non-human primates

Purpose: Non-human primate models of deep brain stimulation (DBS) play an increasingly important role in the exploration of DBS mechanisms. The establishment and recognized usefulness of such models depend on the precise positioning of the stimulating targets and electrode implants. The optimal method of targeting remains controversial. Materials and methods: This paper described an improved stereotactic procedure that uses a self-developed adaptor to improve accuracy. This involved: (1) connecting clinical stereotactic devices with the skull of primates using a self-developed adaptor; (2) pre-operation targeting via magnetic resonance imaging (MRI); (3) target re-checking by microelectrode recording (MER); (4) DBS electrode implantation; (5) post-operative MRI verification of electrode placement and (6) positioning confirmation by DBS programming. Results: Use of the adaptor enabled clinical stereotactic surgery, pre-operative MRI targeting, microelectrode mapping and post-operative verification in primate DBS operations. Discrepancies between achieved and predetermined electrode position were around 0.6 mm. DBS programming improved the motor function of the hemiparkinsonism animals and decreased the numbers of rotation induced by apomorphine, indicating the precise positioning of the stimulating target and successful implanting of electrode using this method. Conclusions: An improved stereotactic procedure was performed during a non-human primate DBS operation using a self-developed adaptor. The accuracy of DBS electrode implantation in non-human primates was improved with this method.

Neurohistopathological findings at the electrode-tissue interface in long-term deep brain stimulation: systematic literature review, case report, and assessment of stimulation threshold safety.

Despite the widespread use of deep brain stimulation (DBS) in the treatment of neurologic disorders for over a quarter of a century, there has not been a systematic review and analyses of cases in which long-term postmortem clinic-pathologic data have been collected demonstrating the effects of chronically implanted electrodes and electrical stimulation on human brain tissue. Our objective is to provide a comprehensive systematic review of the literature on clinicopathologic findings of DBS tissue-electrode interface (TEI) and to determine types and prevalences of neuropathological findings among electrode materials and stimulation parameters and to augment this with previously unpublished histopathological data, images, and analyses from a DBS case implanted for 12 years, providing the longest duration histopathological follow-up. A Medline literature review identified DBS cases upon which postmortem clinicopathologic follow-up was performed with adequate characterization of TEI. Direct follow-up with authors augmented this with unpublished data and neuropathological details. We identified 40 cases, mean age 59.1 ± 13.0 (range: 21-88) years, involving 58 implanted DBS electrodes. The mean postmortem histopathological follow-up of the implanted DBS electrodes was 22.2 ± 29.2 (range: 0.067-146) months, including our case with a 12-year follow-up. The following histological changes were identified: fibrous sheaths (5-25 μm thickness) surrounding the electrode (94%), fibrillary gliosis (73%), reactive astrocytes (78%), multinucleated giant cells (75%), mononuclear leukocytes (92%), and macrophages (91%). Microglial activation (60%), axonal spheroids (64%), and neuronal loss (60%) were less common and absent at 12-year follow-up in the index case. This is seventh case reporting T cell presence at the TEI. Neuropathological findings from published cases and our 12-year follow-up index case confirm the long-term safety of neuromodulation and stimulation thresholds and demonstrate persistence of T cells and occasional subclinical focal tissue injury.

O28: Comparison of the language lateralizations suggested by magnetoencephalography and navigated transcranial magnetic stimulation in healthy subjects using a picture naming task

O28: Comparison of the language lateralizations suggested by magnetoencephalography and navigated transcranial magnetic stimulation in healthy subjects using a picture naming task

O29: Beyond skeletomotor function of human basal ganglia: oculomotor, visual and affective neurons

Deep brain stimulation (DBS) of targets in basal ganglia is an effective treatment of motor dysfunction in Parkinson’s disease and primary dystonia. However this treatment may be accompanied by unwanted non-motor side effects. To confirm their neurophysiological nature we searched for any neurons in the subthalamic nucleus (STN), substantia nigra pars reticulata (SNr) and globus pallidus (GP) involved in processing of visually presented emotional scenes. Nineteen Parkinson’s disease patients, which underwent implantation of DBS electrodes to STN or GP, were investigated with simultaneous intraoperative microelectrode recordings and single channel electrooculography during a visual emotional task containing a series of photographs varying in emotional valence and arousal. Recordings were analyzed by the WaveClus program which allowed for detection and sorting of individual neurons. Out of 183 neurons that were detected, 130 were found in the STN, 30 in the SNr and 23 in the GP. Twenty percent of the neurons in each of these structures showed eye movement-related activity. In the STN, we observed 35 neurons whose firing rate changed significantly within first 500 ms after presentation of a photograph suggesting their participation in visual or attentional mechanisms. Activity of 14 STN neurons showed significant changes during 500–1500 ms interval in alpha band of the instantaneous firing rate related to the emotional content of presented photographs. Activity of 8 of neurons was related to the arousal while activity of another 6 neurons was changing in relation to the emotional valence. Our results showed that basal ganglia contain relatively high share of oculomotor neurons suggesting their critical role in eye-movement control. In addition, the STN neurons involved in visual processing and in transmission of emotional information provide evidence of separate management of the affective dimensions of valence and arousal. Therefore, it is not surprising that DBS may have various non-motor consequences. Supported by grants: IGA MZ CR NT12282–5/2011; research projects: MSM 0021620849, MSM 6840770012 and PRVOUK-P26/LF1/4.

Brain shift during bur hole-based procedures using interventional MRI.

OBJECT.: Brain shift during minimally invasive, bur hole-based procedures such as deep brain stimulation (DBS) electrode implantation and stereotactic brain biopsy is not well characterized or understood. We examine shift in various regions of the brain during a novel paradigm of DBS electrode implantation using interventional imaging throughout the procedure with high-field interventional MRI. Serial MR images were obtained and analyzed using a 1.5-T magnet prior to, during, and after the placement of DBS electrodes via frontal bur holes in 44 procedures. Three-dimensional coordinates in MR space of unique superficial and deep brain structures were recorded, and the magnitude, direction, and rate of shift were calculated. Measurements were recorded to the nearest 0.1 mm. Shift ranged from 0.0 to 10.1 mm throughout all structures in the brain. The greatest shift was seen in the frontal lobe, followed by the temporal and occipital lobes. Shift was also observed in deep structures such as the anterior and posterior commissures and basal ganglia; shift in the pallidum and subthalamic region ipsilateral to the bur hole averaged 0.6 mm, with 9% of patients having over 2 mm of shift in deep brain structures. Small amounts of shift were observed during all procedures; however, the initial degree of shift and its direction were unpredictable. Brain shift is continual and unpredictable and can render traditional stereotactic targeting based on preoperative imaging inaccurate even in deep brain structures such as those used for DBS.

18. Beyond skeletomotor function of human basal ganglia: Oculomotor, visual and affective neurons

Deep brain stimulation (DBS) of targets in basal ganglia is an effective treatment of motor dysfunction in Parkinson’s disease and primary dystonia. However this treatment may be accompanied by unwanted non-motor side effects. To confirm their neurophysiological nature we searched for any neurons in the subthalamic nucleus (STN), substantia nigra pars reticulata (SNr) and globus pallidus (GP) involved in processing of visually presented emotional scenes. Nineteen Parkinson’s disease patients, which underwent implantation of DBS electrodes to STN or GP, were investigated with simultaneous intraoperative microelectrode recordings and single channel electrooculography during a visual emotional task containing a series of photographs varying in emotional valence and arousal. Recordings were analyzed by the WaveClus program which allowed for detection and sorting of individual neurons. Out of 183 neurons that were detected, 130 were found in the STN, 30 in the SNr and 23 in the GP. Twenty percent of the neurons in each of these structures showed eye movement-related activity. In the STN, we observed 35 neurons whose firing rate changed significantly within first 500 ms after presentation of a photograph suggesting their participation in visual or attentional mechanisms. Activity of 14 STN neurons showed significant changes during 500–1500 ms interval in alpha band of the instantaneous firing rate related to the emotional content of presented photographs. Activity of 8 of neurons was related to the arousal while activity of another 6 neurons was changing in relation to the emotional valence. Our results showed that basal ganglia contain relatively high share of oculomotor neurons suggesting their critical role in eye-movement control. In addition, the STN neurons involved in visual processing and in transmission of emotional information provide evidence of separate management of the affective dimensions of valence and arousal. Therefore, it is not surprising that DBS may have various non-motor consequences. Supported by grants: IGA MZ ČR NT12282–5/2011; research projects: MŠM 0021620849, MŠM 6840770012 and PRVOUK-P26/LF1/4.

Different patterns of local field potentials from limbic DBS targets in patients with major depressive and obsessive compulsive disorder

The role of distinct limbic areas in emotion regulation has been largely inferred from neuroimaging studies. Recently, the opportunity for intracranial recordings from limbic areas has arisen in patients undergoing deep brain stimulation (DBS) for neuropsychiatric disorders including major depressive disorder (MDD) and obsessive compulsive disorder (OCD). Here we test the hypothesis that distinct temporal patterns of local field potential (LFP) activity in the human limbic system reflect disease state and symptom severity in MDD and OCD patients. To this end, we recorded LFPs via implanted DBS electrodes from the bed nucleus of stria terminalis (BNST area) in 12 patients (5 OCD, 7 MDD) and from the subgenual cingulate cortex in 7 MDD patients (CG25 area). We found a distinct pattern of oscillatory activity with significantly higher α-power in MDD compared with OCD in the BNST area (broad α-band 8-14 Hz; P<0.01) and a similar level of α-activity in the CG25 area as in the BNST area in MDD patients. The mean α-power correlated with severity of depressive symptoms as assessed by the Beck depression inventory in MDD (n=14, r=0.55, P=0.042) but not with severity of obsessive compulsive symptoms in OCD. Here we show larger α-band activity in MDD patients compared with OCD recorded from intracranial DBS targets. Our results suggest that α-activity in the limbic system may be a signature of symptom severity in MDD and may serve as a potential state biomarker for closed loop DBS in MDD.

Postoperative delirium in Parkinson’s disease patients following deep brain stimulation surgery

Deep brain stimulation (DBS) surgery is an effective treatment for patients with advanced Parkinson’s disease. Delirium in hospitalized Parkinson’s disease patients is common and often leads to prolonged hospital stays. This study reports on the incidence and etiology of postoperative delirium following DBS surgery. Patients (n=59) with advanced Parkinson’s disease underwent bilateral (n=56) or unilateral (n=3) DBS electrode implant surgery, followed 1week later with surgical placement of DBS generators. The development of delirium during either hospital stay was evaluated retrospectively from the hospital chart. Potential causes of delirium were evaluated, including history of delirium, opiate equivalents, medication administration delays and missed doses during hospitalization, and Parkinson’s disease duration. Delirium following implantation of DBS electrodes was common (22% of patients). It was less commonly associated with generator placement (10%). A history of delirium, age, and disease duration were positive predictors of delirium. Opiate equivalent doses were negatively correlated with delirium. Missed Parkinson’s medication doses (53% of patients) and delayed administration (81% of patients) were common, and had a slight relation with delirium. Delirium was not related to complexity of medication regimen or use of dementia medications. Despite the presence of delirium most patients still only required a single night in the hospital post-surgery (67%). Prolonged hospital stay was due not only to delirium but also severe off states and other medical issues. Recognition and expectant management of delirium is best accomplished in a multidisciplinary setting, including the patient’s family and nursing, pharmacy and neurological surgery staff.

Localization of deep brain stimulation electrodes via metal artifacts in CT images.

In Deep Brain Stimulation (DBS), the location of implanted electrodes in the brain has direct influence on the therapeutic effect of the treatment. This work deals with estimating the position of the implanted DBS electrodes from the images registered by X-ray Computed Tomography (CT) scanners. A technique named junction method that takes advantage of the streak artifacts created by the metal parts of the electrodes in CT images is proposed for this purpose. To start with, the brain image is extracted by defining a brain mask. Next, the edges are intensified by applying a Gaussian convolution operator followed by a measure of the second derivative of the image along all directions in the image plane. Criteria of adjacency and length are applied to the lines detected by the Hough transform to distinguish between tracks of streak artifacts and the brain structure. At some points, straight lines are distorted by noise. To handle this issue, all lines that fit same line equation are merged. The horizontal line connecting the two DBS electrodes (one in each cerebral hemisphere) is called electrode line. To specify the electrodes position, intersections of the electrode line with every other line are marked. Finally, to obtain the vertical position estimate, the above algorithm is applied to the image stack.

Protocol for the microelectrode recording of neuronal activity in head-restrained, alert animals

Background: Neuronal activity microelectrode recording (MER) is the standard means of intrasurgical target localization for Deep Brain Stimulation electrode implantation. Since MER is /INS;usually only obtained for patients with Parkinson'/INS;s disease under local anesthesia, an important question is how the neuronal discharge characteristics of the Basal Ganglia vary with the level of alertness.