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  • 1.
    Alonso, Fabiola
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. University of Applied Sciences and Arts Northwestern Switzerland.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Influence on Deep Brain Stimulation from Lead Design, Operating Mode and Tissue Impedance Changes – A Simulation Study2015In: Brain Disorders and Therapy, ISSN 2168-975X, Vol. 4, no 3, article id 1000169Article in journal (Refereed)
    Abstract [en]

    Background: Deep brain stimulation (DBS) systems in current mode and new lead designs are recently available. To switch between DBS-systems remains complicated as clinicians may lose their reference for programming. Simulations can help increase the understanding.

    Objective: To quantitatively investigate the electric field (EF) around two lead designs simulated to operate in voltage and current mode under two time points following implantation.

    Methods: The finite element method was used to model Lead 3389 (Medtronic) and 6148 (St Jude) with homogenous surrounding grey matter and a peri-electrode space (PES) of 250 μm. The PES-impedance mimicked the acute (extracellular fluid) and chronic (fibrous tissue) time-point. Simulations at different amplitudes of voltage and current (n=236) were performed using two different contacts. Equivalent current amplitudes were extracted by matching the shape and maximum EF of the 0.2 V/mm isolevel.

    Results: The maximum EF extension at 0.2 V/mm varied between 2-5 mm with a small difference between the leads. In voltage mode EF increased about 1 mm at acute compared to the chronic PES. Current mode presented the opposite relationship. Equivalent EFs for lead 3389 at 3 V were found for 7 mA (acute) and 2.2 mA (chronic).

    Conclusions: Simulations showed a major impact on the electric field extension between postoperative time points. This may explain the clinical decisions to reprogram the amplitude weeks after implantation. Neither the EF extension nor intensity is considerably influenced by the lead design.

  • 2.
    Alonso, Fabiola
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Vogel, Dorian
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Institute for Medical and Analytical Technologies and Department of Biomedical Engineering, University of Applied Sciences and Art Northwestern Switzerland.
    Comparison between intraoperative and chronic and deep brain stimulation2017Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION

    The success of the deep brain stimulation (DBS) therapy relies primarily in the localization of the implanted electrode, implying the need of utmost accuracy in the targeting process. Intraoperative microelectrode recording and stimulation tests are a common procedure before implanting the permanent DBS lead to determine the optimal position with a large therapeutic window where side effects are avoided and the best improvement of the symptoms is achieved. Differences in dimensions and operating modes exist between the exploration and the permanent DBS electrode which might lead to different stimulation fields, even when ideal placement is achieved. The aim of this investigation is to compare the electric field (EF) distribution around the intraoperative and the chronic electrode, assuming that both have exactly the same position.

    METHODS

    3D models of the intraoperative exploration electrode and the chronically implanted DBS lead 3389 (Medtronic Inc., USA) were developed using COMSOL 5.2 (COMSOL AB, Sweden). Patient-specific MR images were used to determine the conductive medium around the electrode. The exploration electrode and the first DBS contact were set to current and voltage respectively (0.2mA(V) - 3 mA(V) in 0.1 mA(V) steps). The intraoperative model included the grounded guide tube used to introduce the exploration electrode; for the chronic DBS model, the outer boundaries were grounded and the inactive contacts were set to floating potential considering a monopolar configuration. The localization of the exploration and the chronic electrode was set according to the planned trajectory. The EF was visualized and compared in terms of volume and extension using a fixed isocontour of 0.2 V/mm.

    RESULTS

    The EF distribution simulated for the exploration electrode showed the influence of the parallel trajectory and the grounded guide tube. For an amplitude of e.g. 2 mA/2 V, the EF extension of the intraoperative was 0.6 mm larger than the chronic electrode at the target level; the corresponding difference in volume was 76.1 mm3.

    CONCLUSION

    Differences in the EF shape between the exploration and the chronic DBS electrode have been observed using patient-specific models. The larger EF extension obtained for the exploration electrode responds to its higher impedance and the use of current controlled stimulation. The presence of EF around the guide tube and the influence of the parallel trajectory require further experimental and clinical evaluation.

  • 3.
    Hemm, Simone
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Richter, Johan
    Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL. Linköping University, Department of Biomedical Engineering.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Laser doppler for guidance during DBS-typical optical trajectories toward Vim and STN2012Conference paper (Other academic)
  • 4.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Institute for Medical and Analytical Technologies, University of Applied Sciences and Art Northwestern Switzerland, Basel.
    Patient-specific electric field simulations and acceleration measurements for intraoperative test-stimulations2014Conference paper (Other academic)
  • 5.
    Hemm-Ode, Simone
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Correlation between laser Doppler measurements and anatomy during deep brain stimulation surgery2012In: Biomedical Engineering, ISSN 0006-3398, E-ISSN 1573-8256, Vol. 57Article in journal (Refereed)
    Abstract [en]

    Introduction

    In Deep Brain Stimulation (DBS) the save, accurate and precise electrode implantation is essential. We have previously presented an optical technique for intra-operative measurements during DBS implantation. The aim of the present study was to establish the link between anatomy and total light intensity (TLI, the greyness of the tissue) and microvascular perfusion recordings.

    Methods

    Twelve patients (6 subthalamic nucleus STN, 6 ventral intermediate nucleus Vim) referred for unilateral or bilateral DBS-implantation for the treatment of essential tremor or Parkinson’s disease were included in the study. Stereotactic CT imaging was used for planning of the trajectories and targets (n=22). Measurement of the TLI and the microvascular perfusion were performed in mm-steps along the trajectory. TLI and perfusion data were post-processed to “optical trajectories” ranging from the cortex towards the target. These were compared with anatomy along the final trajectories by the use of a brain atlas and Surgiplan.

    Results

    Post-processing of the TLI signal showed a clear relationship with anatomy. Characteristic median curves were determined. The curve normally started with low values for STN and Vim patients when in cortex. When the probe entered white matter the TLI increased and stayed at this level until it passed in the vicinity to putamen, caudate nucleus or ventricle. A statistical significant difference (p<0.05) could be shown between white matter and putamen and between white matter and the target area. Concerning microvascular perfusion, high values were often seen in the cortex and low ones in white matter (significant statistical difference: p<0.05). In one case a small bleeding was suspected during surgery with the optical technique. This was confirmed with post-operative CT.

    Conclusion

    In summary the optical technique show promising results and typical trajectories were defined towards the STN and Vim, but further evaluation is necessary in order to refine the “optical bar codes” towards specific DBS-targets.

  • 6.
    Shah, Ashesh
    et al.
    Institute for Medical and Analytical Technologies, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland FHNW, Muttenz, Switzerland.
    Alonso, Fabiola
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Lemarie, Jean-Jacques
    Clermont Université, Université d'Auvergne, EA 3295, Equipe de recherche en signal et imagerie médicale, Image- Guided Clinical Neuroscience and Connectomics (IGCNC), BP 10448, F-63000 Clermont-Ferrand, France/CHU Clermont-Ferrand, Service de Neurochirurgie, F-63003 Clermont-Ferrand, France..
    Pison, Daniela
    Institute for Medical and Analytical Technologies, School of Life Sciences, University of Applied Sciences and Arts Northwestern Switzerland FHNW, Muttenz, Switzerland..
    Coste, Jérôme
    Université Clermont Auvergne, Université d’Auvergne, EA 7282, Image Guided Clinical Neurosciences and Connectomics (IGCNC), Clermont-Ferrand, France; Service de Neurochirurgie, Hôpital Gabriel-Montpied, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand, France..
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Schkommodau, Erik
    Institute for Medical and Analytical Technologies, University of Applied Sciences and Art Northwestern Switzerland.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Institute for Medical and Analytical Technologies and Department of Biomedical Engineering, University of Applied Sciences and Art Northwestern Switzerland.
    Learning more about the optimal anatomical position for deep brain stimulation in essential tremor patients: 3D visualisation of intraoperative stimulation test results2017Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION

    The outcome of deep brain stimulation (DBS) depends heavily on the position of the implanted lead. After a preoperative anatomical planning, most groups collect numerous intraoperative data such as therapeutic effects induced by stimulation tests. To choose the final implant position, physicians “mentally” visualise all available data. The aim of the present work was to develop a method visualising intraoperative stimulation test results, patient’s images, electric field (EF) simulations for the patient-specific stimulation conditions and the corresponding therapeutic effects quantitatively evaluated by accelerometry. The application to five essential tremor (ET) patients should give a first idea about the optimal target position. 

    METHODS

    In Clermont-Ferrand University Hospital the anatomic target structure and the neighbouring structures were manually outlined, a target and a trajectory defined and two parallel trajectories per hemisphere intraoperatively evaluated. Stimulation tests were performed at 7 to 8 positions per trajectory and several stimulation current amplitudes. The therapeutic effect was evaluated using a previously published method based on accelerometry. Finite element models and simulations were performed for up to three stimulation amplitudes per position and EF isosurfaces (0.2V/mm) were extracted. For the 3D visualization of the numerous overlapping isosurfaces, we generated “improvement maps” by assigning to each voxel within the isosurfaces the highest tremor improvement. Those maps were visualized together with anatomical images, delineated structures and trajectories (Paraview, Kitware Inc). The method was applied to 5 ET patients implanted in the ventro-intermediate nucleus of the thalamus (VIM). Results were analysed by the neurosurgeon regarding the optimal implant position.  

    RESULTS

    The clinical teams were able to identify the optimal implant position for all patients with more ease and in less time compared to the routine discussion using pen and paper. Additionally, for 7 of the 9 improvement maps, the highest improvement region was found to be in the posterior subthalamic area, inferior and posterior to the VIM.

    CONCLUSION

    Improvement maps assist the clinicians in determining the optimal implant location of the chronic DBS lead. Results support findings of other studies that the fibre tracts in the posterior subthalamic area like prelemniscal radiations may be responsible for alleviating tremor in ET patients.

  • 7.
    Wårdell, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Haj-Hosseini, Neda
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Institute for Medical and Analytical Technologies, University of Applied Sciences and Art Northwestern Switzerland, Basel.
    Comparison between Optical and MRI Trajectories in Stereotactic Neurosurgery2014In: XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013 : MEDICON 2013, 25 - 28 September 2013, Seville, Spain / [ed] Laura M. Roa Romero, 2014, p. 49-51Conference paper (Refereed)
    Abstract [en]

    Deep brain stimulation (DBS) is an effective treatment for movement disorders e.g. Parkinson's disease. Thin electrodes are implanted into the deep brain structures by means of stereotactic technique and electrical stimulations are delivered to the brain tissue. Accuracy and safety during the implantation is important for optimal stimulation effect and minimization of bleedings. In addition to microelectrode recording and impedance measurements, intraoperative optical measurements using laser Doppler perfusion monitoring (LDPM) have previously been suggested as guidance tool during stereotactic DBS implantations. In this study we compare optical trajectories, recorded with LDPM ranging from cortex towards the subthalamic nucleus (STN), to the corresponding magnetic resonance imaging (MRI) trajectories. Inversed gray scales from the T2-weighted MRI were used for comparison with the total light intensity (TLI) representing tissue grayness. Both curves followed a general tendency with a deep dip in the vicinity to the left ventricle. MRI trajectories might help in predicting the optical trajectory but further studies including more data and fine tuning of the comparative methodology are required

  • 8.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Institute for Medical and Analytical Technologies, University of Applied Sciences and Art Northwestern Switzerland, Basel.
    Optical and microvascular measurements for guidance during DBS implantation2014Conference paper (Other academic)
  • 9.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering. University of Applied Sciences and Arts Northwestern Switzerland, Muttenz , Switzerland.
    Rejmstad, Peter
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    High-Resolution Laser Doppler Measurements of Microcirculation in the Deep Brain Structures: A Method for Potential Vessel Tracking.2016In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 94, no 1, p. 1-9Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Laser Doppler flowmetry (LDF) can be used to measure cerebral microcirculation in relation to stereotactic deep brain stimulation (DBS) implantations.

    OBJECTIVE: To investigate the microcirculation and total light intensity (TLI) corresponding to tissue grayness in DBS target regions with high-resolution LDF recordings, and to define a resolution which enables detection of small vessels.

    METHODS: Stereotactic LDF measurements were made prior to DBS implantation with 0.5-mm steps in the vicinity to 4 deep brain targets (STN, GPi, Vim, Zi) along 20 trajectories. The Mann-Whitney U test was used to compare the microcirculation and TLI between targets, and the measurement resolution (0.5 vs. 1 mm). The numbers of high blood flow spots along the trajectories were calculated.

    RESULTS: There was a significant difference (p < 0.05) in microcirculation between the targets. High blood flow spots were present at 15 out of 510 positions, 7 along Vim and GPi trajectories, respectively. There was no statistical difference between resolutions even though both local blood flow and TLI peaks could appear at 0.5-mm steps.

    CONCLUSIONS: LDF can be used for online tracking of critical regions presenting blood flow and TLI peaks, possibly relating to vessel structures and thin laminas along stereotactic trajectories.

  • 10.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Rejmstad, Peter
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Hemm-Ode, Simone
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Institute for Medical and Analytical Technologies, University of Applied Sciences and Art Northwestern Switzerland, Basel.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Microvascular Blood Flow in the Deep Brain Structures - Laser Doppler Measurements during DBS-implantations2014In: Movement Disorders 2014, Volym 29, Suppl 1 :1271, 2014Conference paper (Other academic)
  • 11.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hemm, Simone
    Fachhochschule Nordwestschweiz.
    Intraoperative laser doppler measurements for navigation during deep brain stimulation implantation2012Conference paper (Other academic)
  • 12.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Zsigmond, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Richter, Johan
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Neurosurgery.
    Hemm, Simone
    Linköping University, Department of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Institute for Medical and Analytical Technologies, University of Applied Sciences and Arts Northwestern Switzerland, Muttenz, Switzerland.
    Optical Guidance System for Deep Brain Stimulation Surgery: from Experimental Studies to Clinical Use2018In: , Hollywood, Florida, United States, 2018, article id CTh2B.3Conference paper (Refereed)
    Abstract [en]

    Laser Doppler flowmetry (LDF) has been adapted for optical guidance during stereotactic deep brain stimulation (DBS) surgery. It has been used in more than 130 DBS implantations. The necessary steps to go from experimental studies to clinical use in the neurosurgical setting are reviewed.

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