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  • 1.
    Akbarian-Tefaghi, Ladan
    et al.
    Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London, UK.
    Akram, Harith
    Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London, UK.
    Johansson, Johannes
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Zrinzo, Ludvic
    Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London, UK.
    Kefalopoulou, Zinovia
    Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London, UK.
    Limousin, Patricia
    Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London, UK.
    Joyce, Eileen
    Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London, UK.
    Hariz, Marwan
    Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London, UK.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Foltynie, Tom
    Unit of Functional Neurosurgery, Sobell Department of Motor Neuroscience, UCL Institute of Neurology, London, UK.
    Refining the Deep Brain Stimulation Target within the Limbic Globus Pallidus Internus for Tourette Syndrome2017In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 95, no 4, p. 251-258Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Deep brain stimulation (DBS) in patients with severe, refractory Tourette syndrome (TS) has demonstrated promising but variable results thus far. The thalamus and anteromedial globus pallidus internus (amGPi) have been the most commonly stimulated sites within the cortico-striato thalamic circuit, but an optimal target is yet to be elucidated.

    OBJECTIVES: This study of 15 patients with long-term amGPi DBS for severe TS investigated whether a specific anatomical site within the amGPi correlated with optimal clinical outcome for the measures of tics, obsessive compulsive behaviour (OCB), and mood.

    METHODS: Validated clinical assessments were used to measure tics, OCB, quality of life, anxiety, and depression before DBS and at the latest follow-up (17-82 months). Electric field simulations were created for each patient using information on electrode location and individual stimulation parameters. A subsequent regression analysis correlated these patient-specific simulations to percentage changes in outcome measures in order to identify any significant voxels related to clinical improvement.

    RESULTS: A region within the ventral limbic GPi, specifically on the medial medullary lamina in the pallidum at the level of the AC-PC, was significantly associated with improved tics but not mood or OCB outcome.

    CONCLUSIONS: This study adds further support to the application of DBS in a tic-related network, though factors such as patient sample size and clinical heterogeneity remain as limitations and replication is required.

  • 2.
    Antonsson, Johan
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Eriksson, Ola
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Lundberg, Peter
    Linköping University, Department of Medical and Health Sciences, Radiation Physics. Linköping University, Faculty of Health Sciences.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Optical measurements during experimental stereotactic radiofrequency lesioning2006In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 84, no 2-3, p. 118-124Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate in vivo a laser Doppler measurement system in porcine brain tissue during thermal lesioning. A 2-mm monopolar radiofrequency lesioning electrode was equipped with optical fibers in order to monitor the lesioning procedure. Laser Doppler and backscattered light intensity signals were measured along the electrode trajectory and during bilateral lesioning in the central gray (70, 80 and 90°C, n = 14). The time course of the coagulation process could be followed by optical recordings. Two separate groups of tissue were identified from the intensity signals. The changes in the perfusion levels in both groups displayed significant changes (p < 0.05, n = 48) at all temperature settings, while backscattered light intensity was significant for only one group at the different temperatures (p < 0.05, n = 39). These results indicate that optical measurements correlate with lesion development in vivo. The study also indicates that it is possible to follow the lesioning process intra-operatively.

  • 3.
    Berntsson, Shala G.
    et al.
    Uppsala Univ, Sweden.
    Gauffin, Helena
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Neurology.
    Melberg, Atle
    Uppsala Univ, Sweden.
    Holtz, Anders
    Uppsala Univ, Sweden.
    Landtblom, Anne-Marie
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Local Health Care Services in Central Östergötland, Department of Neurology. Uppsala Univ, Sweden.
    Inherited Ataxia and Intrathecal Baclofen for the Treatment of Spasticity and Painful Spasms2019In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 97, no 1, p. 18-23Article in journal (Refereed)
    Abstract [en]

    Background: Intrathecal baclofen (ITB) treatment is considered a powerful tool in the management of severe spasticity in neurological conditions such as multiple sclerosis, cerebral palsy, and traumatic spinal cord and brain injury. 

    Objectives: The objective of this study was to assess the effectiveness of the ITB in patients with inherited ataxia suffering from severe painful spasms and/or spasticity. 

    Method: A total of 5 patients with spinocerebellar ataxia 3 or 7 or Friedreich’s ataxia were included in this observational multicenter study. The patients were interviewed and completed outcome measures assessing pain (The Brief Pain Inventory), fatigue (Fatigue Severity Scale), and life satisfaction (LiSAT-9) before and 1 year after the treatment. Spasticity (Modified Ashworth Scale) and spasm frequency (SPFS) were measured objectively for each patient. 

    Results: The mean treatment time was 1.9 years. Evaluation of established standard forms revealed symptomatic relief from spasticity, spasms, pain, and fatigue in addition to improved body posture, sleep, and life satisfaction after ITB treatment. 

    Conclusions: We report the potential beneficial effects of ITB treatment in patients with inherited ataxia who also suffer from spasticity/spasms. ITB treatment indication in neurological disorders allows for extension to the treatment of spasticity/ spasms in patients with hereditary ataxia.

  • 4.
    Fytagoridis, Anders
    et al.
    Karolinska Institute, Sweden; Umeå University, Sweden; University of Queensland, Australia.
    Heard, Tomas
    University of Queensland, Australia.
    Samuelsson, Jennifer
    Umeå University, Sweden; Sahlgrens University Hospital, Sweden.
    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.
    Jiltsova, Elena
    University of Uppsala Hospital, Sweden.
    Skyrman, Simon
    Karolinska Institute, Sweden.
    Skoglund, Thomas
    Sahlgrens University Hospital, Sweden.
    Coyne, Terry
    University of Queensland, Australia; Brizbrain and Spine, Australia.
    Silburn, Peter
    University of Queensland, Australia.
    Blomstedt, Patric
    Umeå University, Sweden.
    Surgical Replacement of Implantable Pulse Generator in Deep Brain Stimulation: Adverse Events and Risk Factors in a Multicenter Cohort2016In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 94, no 4, p. 235-239Article in journal (Refereed)
    Abstract [en]

    Background: Deep brain stimulation (DBS) is a growing treatment modality, and most DBS systems require replacement of the implantable pulse generator (IPG) every few years. The literature regarding the potential impact of adverse events of IPG replacement on the longevity of DBS treatments is rather scarce. Objective: To investigate the incidence of adverse events, including postoperative infections, associated with IPG replacements in a multicenter cohort. Methods: The medical records of 808 patients from one Australian and five Swedish DBS centers with a total of 1,293 IPG replacements were audited. A logistic regression model was used to ascertain the influence of possible predictors on the incidence of adverse events. Results: The overall incidence of major infections was 2.3% per procedure, 3.7% per patient and 1.7% per replaced IPG. For 28 of 30 patients this resulted in partial or complete DBS system removal. There was an increased risk of infection for males (OR 3.6, p = 0.026), and the risk of infection increased with the number of prior IPG replacements (OR 1.6, p amp;lt; 0.005). Conclusions: The risk of postoperative infection with DBS IPG replacement increases with the number of previous procedures. There is a need to reduce the frequency of IPG replacements. (C) 2016 S. Karger AG, Basel

  • 5.
    Fytagoridis, Anders
    et al.
    Umeå University, Sweden .
    Sjoberga, Rickard L.
    Umeå University, Sweden .
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fredricks, Anna
    Umeå University, Sweden .
    Nyberg, Lars
    Umeå University, Sweden .
    Blomstedt, Patric
    Umeå University, Sweden .
    Effects of Deep Brain Stimulation in the Caudal Zona Incerta on Verbal Fluency2013In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 91, no 1, p. 24-29Article in journal (Refereed)
    Abstract [en]

    Background: Deep brain stimulation (DBS) of the caudal zona incerta (cZi) is a relatively unexplored and promising treatment in patients with severe essential tremor (ET). Preliminary data further indicate that the ability to produce language may be slightly affected by the treatment. Objective: To evaluate the effects on verbal fluency following cZi DBS in patients with ET. Method: Seventeen consecutive patients who had undergone DBS of the cZi for ET were tested regarding verbal fluency before surgery, 3 days after surgery and after 1 year. Ten patients were also evaluated by comparing performance on versus off stimulation after 1 year. Results: The total verbal fluency score decreased slightly, but significantly, from 22.7 (SD = 10.9) before surgery to 18.1 (SD = 7.5) 3 days after surgery (p = 0.036). After 1 year the score was nonsignificantly decreased to 20.1 (SD = 9.7, p = 0.2678). There was no detectable difference between stimulation on and off after 1 year. Conclusion: There was a tendency of an immediate and mostly transient postoperative decline in verbal fluency following cZi DBS for ET. In some of the patients this reduction was, however, more pronounced and also sustained over time.

  • 6.
    Fytagoridis, Anders
    et al.
    Department of Pharmacologyand Clinical Neuroscience, Section of Neurosurgery, Umeå University, Umeå, Sweden.
    Åström, Mattias
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, Faculty of Science & Engineering.
    Samuelsson, Jörgen
    Unit of Functional and Stereotactic Neurosurgery, Department of Pharmacology and Clinical Neuroscience, Umeå University, Umeå.
    Blomstedt, Patric
    Department of Pharmacology and Clinical Neuroscience, Division of Neurosurgery, Umeå University, Umeå, Sweden.
    Deep Brain Stimulation of the Caudal Zona Incerta: Tremor Control in Relation to the Location of Stimulation Fields2016In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 94, no 6, p. 363-370Article in journal (Refereed)
    Abstract [en]

    Background: The caudal zona incerta (cZi) and posterior subthalamic area (PSA) are an emerging deep brain stimulation (DBS) target for essential tremor (ET). Objectives: To evaluate the efficacy of tremor control in relation to the anatomical locations of stimulation fields in 50 patients with ET and DBS of the cZi. Methods: A total of 240 contacts were evaluated separately with monopolar stimulation, and amplitudes were optimized for improvement of tremor and hand function. Stimulation fields, i.e., volumes of neural activation, were simulated for each optimized setting and assembled into probabilistic stimulation maps (PSMs). Results: There were differences in the anatomical distribution of PSMs associated with good versus poor tremor control. The location of PSMs which achieved good and excellent tremor control corresponded well with the PSM for the clinically used settings, and they were located within the superior part of the PSA. Conclusions: PSMs may serve as a useful tool for defining the most efficacious anatomical location of stimulation. The best tremor control in this series of cZi DBS was achieved with stimulation of the superior part of the PSA, which corresponds to the final part of the cerebellothalamic projections before they reach the ventral lateral thalamus.

  • 7.
    Hirbayashi, Hidehiro
    et al.
    Nara Medical University, Kashihara , Japan.
    Hariz, Marwan
    Umeå University.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Blomstedt, Patric
    Umeå University.
    Impact of Parameters of Radiofrequency Coagulation on Volume of Stereotactic Lesion inPallidotomy and Thalamotomy2012In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 90, no 5, p. 307-315Article in journal (Refereed)
    Abstract [en]

    Background: One of the many reasons why lesional surgery for movement disorders has been more or less abandoned may have been the difficulty in predicting the shape and size of the stereotactic radiofrequency (RF) lesion. Objectives: To analyse the contribution of various RF coagulation parameters towards the volume of pallidotomies and thalamotomies. Methods: The relationship between temperature of coagulation, length of coagulated area and duration of coagulation on the one hand, and lesion volume on the other was retrospectively evaluated. Lesion diameters were measured on stereotactic thin-slice CT and MRI scans, and volumes of lesions were calculated concerning 36 pallidotomies and 14 thalamotomies in 46 patients who were operated using the same RF generator and same RF electrode. Results: The coagulation temperature, length of coagulated area and duration of coagulation were all correlated to the lesion volume. However, for a given length of coagulated area, the lesion´s size was most strongly influenced by the temperature. Despite this clear correlation, and the relatively homogenous coagulation parameters, the lesions’ volumes were markedly scattered. Conclusions: The volume of the stereotactic RF lesions could be correlated with the coagulation parameters, especially the temperature, at a group level, but could not be predicted in individual patients based solely on the RF coagulation parameters.

  • 8.
    Johansson, Johannes D.
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Blomstedt, Patric
    Department of Neurosurgery, Norrland´s University Hospital, Umeå, Sweden.
    Haj-Hosseini, Neda
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Bergenheim, Tommy
    Department of Neurosurgery, Norrland´s University Hospital, Umeå, Sweden.
    Eriksson, Ola
    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.
    Combined diffuse light reflectance and electric impedance measurements for navigation aid in deep brain surgery2009In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 87, no 2, p. 105-113Article in journal (Refereed)
    Abstract [en]

    Aim: The aim of this study is to investigate reflected light intensity combined with impedance for navigation aid during stereotactic neurosurgery.

    Methods: During creation of 21 trajectories for stereotactic implantation of deep brain stimulation electrodes in the globus pallidus internus or subthalamus (zona incerta or subthalamic nucleus), impedance at 512 kHz and reflected light intensity at 780 nm were measured continuously and simultaneously with a radio frequency electrode containing optical fibres. The signals were compared with anatomy determined from pre- and postoperative MRI and CT. The measurements were performed within minutes and signal analysis was done post-operatively.

    Results: Reflected light intensity was low from cortex, lateral ventricle, caudate nucleus and putamen. It was intermediate from globus pallidus and thalamus while it was high from subcortical white matter, internal capsule and the subthalamus. The electric impedance was less consistent but generally low in the cortex, intermediate in subcortical white matter, the putamen, the globus pallidus and the thalamus and high in the internal capsule and the subthalamus.

    Conclusion: Reflected light intensity and electric impedance give complementary information about passed tissue and the combination seems promising for navigation aid during stereotactic neurosurgery.

  • 9.
    Wårdell, Karin
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Blomstedt, P.
    Department of Neurosurgery, University Hospital, Umeå, Sweden.
    Richter, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Antonsson, Johan
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Eriksson, Ola
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Zsigmond, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Neurosurgery. Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurosurgery UHL.
    Bergenheim, A.T.
    Department of Neurosurgery, University Hospital, Umeå, Sweden.
    Hariz, M.I.
    Department of Neurosurgery, University Hospital, Umeå, Sweden, Institute of Neurology, University College London, London, United Kingdom.
    Intracerebral microvascular measurements during deep brain stimulation implantation using laser doppler perfusion monitoring2007In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 85, no 6, p. 279-286Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to investigate if laser Doppler perfusion monitoring (LDPM) can be used in order to differentiate between gray and white matter and to what extent microvascular perfusion can be recorded in the deep brain structures during stereotactic neurosurgery. An optical probe constructed to fit in the Leksell® Stereotactic System was used for measurements along the trajectory and in the targets (globus pallidus internus, subthalamic nucleus, zona incerta, thalamus) during the implantation of deep brain stimulation leads (n = 22). The total backscattered light intensity (TLI) reflecting the grayness of the tissue, and the microvascular perfusion were captured at 128 sites. Heartbeat-synchronized pulsations were found at all perfusion recordings. In 6 sites the perfusion was more than 6 times higher than the closest neighbor indicating a possible small vessel structure. TLI was significantly higher (p < 0.005) and the perfusion significantly lower (p < 0.005) in positions identified as white matter in the respective MRI batch. The measurements imply that LDPM has the potential to be used as an intracerebral guidance tool.

  • 10.
    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.

  • 11.
    Zsigmond, Peter
    et al.
    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.
    Hemm-Ode, Simone
    School of Life Sciences FHNW Institute for Medical and Analytical Technologies.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Optical Measurements during Deep Brain Stimulation Lead Implantation: Safety Aspects2017In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 95, no 6, p. 392-399Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Intracerebral hemorrhage (ICH) is the most feared complication in deep brain stimulation (DBS) surgery. The aim of the study was to evaluate patient safety and outcome using laser Doppler flowmetry (LDF) as guidance tool during DBS implantations.

    METHODS: An LDF probe adapted for the stereotactic system was used as guide for creation of the trajectory. The microcirculation along 83 preplanned trajectories was measured with the guide during DBS surgery for movement disorders. The microvascular blood flow levels were investigated for all measurement positions. Medical record and postoperative radiology were retrospectively reviewed.

    RESULTS: Of 2,963 measurement positions, 234 (7.9%) showed at least a doubled blood flow compared to the surrounding tissue. Of these 2.2% had a more than 5 times higher blood flow in front of the probe tip. Along 1 trajectory, a small ICH was detected during surgery. Increased blood flow was more common close to sulci and verticals.

    CONCLUSION: Real-time LDF measurement of the microcirculation using a forward-looking probe during DBS surgery can detect blood flow peaks and further minimize the risk of developing ICH. No separate guide tube is necessary as the probe also creates the trajectory for the DBS lead.

  • 12.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Medtronic, Sweden; Medtronic, Netherlands.
    Samuelsson, Jennifer
    Umea Univ, Sweden.
    Roothans, Jonas
    Medtronic, Sweden; Medtronic, Netherlands.
    Fytagoridis, Anders
    Umea Univ, Sweden; Karolinska Inst, Sweden.
    Ryzhkov, Maxim
    Medtronic, Sweden; Medtronic, Netherlands.
    Nijlunsing, Rutger
    Medtronic, Sweden; Medtronic, Netherlands.
    Blomstedt, Patric
    Umea Univ, Sweden.
    Prediction of Electrode Contacts for Clinically Effective Deep Brain Stimulation in Essential Tremor2018In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 96, no 5, p. 281-288Article in journal (Refereed)
    Abstract [en]

    Background/Aim: Deep brain stimulation (DBS) is an established neurosurgical treatment that can be used to alleviate symptoms in essential tremor (ET) and other movement disorders. The aim was to develop a method and software tool for the prediction of effective DBS electrode contacts based on probabilistic stimulation maps (PSMs) in patients with ET treated with caudal zona incerta (cZi) DBS. Methods: A total of 33 patients (37 leads) treated with DBS were evaluated with the Essential Tremor Rating Scale (ETRS) 12 months after surgery. In addition, hand tremor and hand function (ETRS items 5/6 and 11-14) were evaluated for every contact during stimulation with best possible outcome without inducing side effects. Prediction of effective DBS electrode contacts was carried out in a retrospective leave-one-out manner based on PSMs, simulated stimulation fields, and a scoring function. Electrode contacts were ranked according to their likelihood of being included in the clinical setting. Ranked electrode contacts were compared to actual clinical settings. Results: Predictions made by the software tool showed that electrode contacts with rank 1 matched the clinically used contacts in 60% of the cases. Contacts with a rank of 1-2 and 1-3 matched the clinical contacts in 83 and 94% of the cases, respectively. Mean improvement of hand tremor and hand function was 79 +/- 21% and 77 +/- 22% for the clinically used and the predicted electrode contacts, respectively. Conclusions: Effective electrode contacts can be predicted based on PSMs in patients treated with cZi DBS for ET. Predictions may in the future be used to reduce the number of clinical assessments that are carried out before a satisfying stimulation setting is defined. (C) 2018 S. Karger AG, Basel

  • 13.
    Åström, Mattias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Tripoliti, Elina
    University College, London.
    Hariz, Mawan I.
    University Hospital, Umeå .
    Zrinzo, Ludvig U.
    University College, London.
    Martinez-Torres, Irene
    University College, London.
    Limousin, Patricia
    University College, London.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Patient-Specific Model-Based Investigation of Speech Intelligibility and Movement during Deep Brain Stimulation2010In: Stereotactic and Functional Neurosurgery, ISSN 1011-6125, E-ISSN 1423-0372, Vol. 88, no 4, p. 224-233Article in journal (Refereed)
    Abstract [en]

    Background/Aims: Deep brain stimulation (DBS) is widely used to treat motor symptoms in patients with advanced Parkinson’s disease. The aim of this study was to investigate the anatomical aspects of the electric field in relation to effects on speech and movement during DBS in the subthalamic nucleus. Methods: Patient-specific finite element models of DBS were developed for simulation of the electric field in 10 patients. In each patient, speech intelligibility and movement were assessed during 2 electrical settings, i.e. 4 V (high) and 2 V (low). The electric field was simulated for each electrical setting. Results: Movement was improved in all patients for both high and low electrical settings. In general, high-amplitude stimulation was more consistent in improving the motor scores than low-amplitude stimulation. In 6 cases, speech intelligibility was impaired during high-amplitude electrical settings. Stimulation of part of the fasciculus cerebellothalamicus from electrodes positioned medial and/or posterior to the center of the subthalamic nucleus was recognized as a possible cause of the stimulation-induced dysarthria. Conclusion: Special attention to stimulation-induced speech impairments should be taken in cases when active electrodes are positioned medial and/or posterior to the center of the subthalamic nucleus.

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