The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform

Mohammad Maarouf - One of the best experts on this subject based on the ideXlab platform.

  • Neuroanatomical background and functional considerations for stereotactic interventions in the H Fields of Forel
    Brain Structure and Function, 2018
    Co-Authors: Clemens Neudorfer, Mohammad Maarouf
    Abstract:

    The H Fields of Forel constitute an intricate neuroanatomical structure that occupies a central position within the posterior subthalamus. Anatomically, it features a dense concentration of fiber bundles including corticofugal, pallidothalamic, cerebellothalamic and other projections that connect functionally relevant areas of the brain. Functionally, the Fields of Forel are embedded within the cortico-striato-thalamo-cortical circuit and constitute the main link between the striatopallidal system and the thalamocortical network. Given the current understanding of basal ganglia involvement in movement disorders and neuropsychiatric disease we sought to investigate the H Fields of Forel as a potential target in stereotactic functional neurosurgery. Although historically recognized in the treatment of movement disorders, behavioral disorders and epilepsy, the significance of the H Fields is considerably diminished today receiving only little attention. Owing to the current lack of reviews addressing the anatomical and functional organization of Forel’s Fields, we aim to deliver an up-to-date overview of the H Fields in this paper. We investigate the complex neuroanatomy and describe the passage of the various fiber systems that course through the posterior subthalamus. We revise the role of Forel’s Fields in the current context of our understanding of cortico-basal ganglia circuitry and discuss the historic relevance of Forel’s Fields during the lesional era. Finally, we provide an outlook regarding the potential of deep brain stimulation in close proximity and within the H Fields of Forel.

  • Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome.
    Frontiers in human neuroscience, 2017
    Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad Maarouf
    Abstract:

    The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the Fields of Forel, namely field H1, as a target for deep brain stimulation. The Fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic ventral nuclear group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients.

  • Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome
    Frontiers Media S.A., 2017
    Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad Maarouf
    Abstract:

    The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation (DBS) is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the Fields of Forel, namely field H1, as a target for DBS. The Fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic ventral nuclear group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients

Clemens Neudorfer - One of the best experts on this subject based on the ideXlab platform.

  • Neuroanatomical background and functional considerations for stereotactic interventions in the H Fields of Forel
    Brain Structure and Function, 2018
    Co-Authors: Clemens Neudorfer, Mohammad Maarouf
    Abstract:

    The H Fields of Forel constitute an intricate neuroanatomical structure that occupies a central position within the posterior subthalamus. Anatomically, it features a dense concentration of fiber bundles including corticofugal, pallidothalamic, cerebellothalamic and other projections that connect functionally relevant areas of the brain. Functionally, the Fields of Forel are embedded within the cortico-striato-thalamo-cortical circuit and constitute the main link between the striatopallidal system and the thalamocortical network. Given the current understanding of basal ganglia involvement in movement disorders and neuropsychiatric disease we sought to investigate the H Fields of Forel as a potential target in stereotactic functional neurosurgery. Although historically recognized in the treatment of movement disorders, behavioral disorders and epilepsy, the significance of the H Fields is considerably diminished today receiving only little attention. Owing to the current lack of reviews addressing the anatomical and functional organization of Forel’s Fields, we aim to deliver an up-to-date overview of the H Fields in this paper. We investigate the complex neuroanatomy and describe the passage of the various fiber systems that course through the posterior subthalamus. We revise the role of Forel’s Fields in the current context of our understanding of cortico-basal ganglia circuitry and discuss the historic relevance of Forel’s Fields during the lesional era. Finally, we provide an outlook regarding the potential of deep brain stimulation in close proximity and within the H Fields of Forel.

  • Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome.
    Frontiers in human neuroscience, 2017
    Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad Maarouf
    Abstract:

    The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the Fields of Forel, namely field H1, as a target for deep brain stimulation. The Fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic ventral nuclear group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients.

  • Deep Brain Stimulation of the H Fields of Forel Alleviates Tics in Tourette Syndrome
    Frontiers Media S.A., 2017
    Co-Authors: Clemens Neudorfer, Faycal El Majdoub, Stefan Hunsche, Klaus Richter, Volker Sturm, Mohammad Maarouf
    Abstract:

    The current rationale for target selection in Tourette syndrome revolves around the notion of cortico-basal ganglia circuit involvement in the pathophysiology of the disease. However, despite extensive research, the ideal target for deep brain stimulation (DBS) is still under debate, with many structures being neglected and underexplored. Based on clinical observations and taking into account the prevailing hypotheses of network processing in Tourette syndrome, we chose the Fields of Forel, namely field H1, as a target for DBS. The Fields of Forel constitute the main link between the striatopallidal system and the thalamocortical network, relaying pallidothalamic projections from core anatomical structures to the thalamic ventral nuclear group. In a retrospective study we investigated two patients suffering from chronic, medically intractable Tourette syndrome who underwent bilateral lead implantation in field H1 of Forel. Clinical scales revealed significant alleviation of tics and comorbid symptoms, namely depression and anxiety, in the postoperative course in both patients

Cameron C. Mcintyre - One of the best experts on this subject based on the ideXlab platform.

  • Anatomical Targets Associated with Abrupt versus Gradual Washout of Subthalamic Deep Brain Stimulation Effects on Bradykinesia
    2015
    Co-Authors: Scott E. Cooper, Klaus G. Driesslein, Angela M. Noecker, Cameron C. Mcintyre, Andre M. Machado, Christopher R. Butson
    Abstract:

    The subthalamic nucleus (STN) is a common anatomical target for deep brain stimulation (DBS) for the treatment of Parkinson’s disease. However, the effects of stimulation may spread beyond the STN. Ongoing research aims to identify nearby anatomical structures where DBS-induced effects could be associated with therapeutic improvement or side effects. We previously found that DBS lead location determines the rate – abrupt vs. gradual – with which therapeutic effect washes out after stimulation is stopped. Those results suggested that electrical current spreads from the electrodes to two spatially distinct stimulation targets associated with different washout rates. In order to identify these targets we used computational models to predict the volumes of tissue activated during DBS in 14 Parkinson’s patients from that study. We then coregistered each patient with a stereotaxic atlas and generated a probabilistic stimulation atlas to obtain a 3-dimensional representation of regions where stimulation was associated with abrupt vs. gradual washout. We found that the therapeutic effect which washed out gradually was associated with stimulation of the zona incerta and Fields of Forel, whereas abruptly-disappearing therapeutic effect was associated with stimulation of STN itself. This supports the idea that multiple DBS targets exist and that current spread from one electrode may activate more than one of them in a given patient, producin

  • anatomical targets associated with abrupt versus gradual washout of subthalamic deep brain stimulation effects on bradykinesia
    PLOS ONE, 2014
    Co-Authors: Sco E Coope, Cameron C. Mcintyre, Andre M. Machado, Klaus Driesslei, Angela M Noecke, Christophe R Utso
    Abstract:

    The subthalamic nucleus (STN) is a common anatomical target for deep brain stimulation (DBS) for the treatment of Parkinson’s disease. However, the effects of stimulation may spread beyond the STN. Ongoing research aims to identify nearby anatomical structures where DBS-induced effects could be associated with therapeutic improvement or side effects. We previously found that DBS lead location determines the rate – abrupt vs. gradual – with which therapeutic effect washes out after stimulation is stopped. Those results suggested that electrical current spreads from the electrodes to two spatially distinct stimulation targets associated with different washout rates. In order to identify these targets we used computational models to predict the volumes of tissue activated during DBS in 14 Parkinson’s patients from that study. We then coregistered each patient with a stereotaxic atlas and generated a probabilistic stimulation atlas to obtain a 3-dimensional representation of regions where stimulation was associated with abrupt vs. gradual washout. We found that the therapeutic effect which washed out gradually was associated with stimulation of the zona incerta and Fields of Forel, whereas abruptly-disappearing therapeutic effect was associated with stimulation of STN itself. This supports the idea that multiple DBS targets exist and that current spread from one electrode may activate more than one of them in a given patient, producing a combination of effects which vary according to electrode location and stimulation settings.

  • patient specific analysis of the volume of tissue activated during deep brain stimulation
    NeuroImage, 2007
    Co-Authors: Christopher R. Butson, Scott E. Cooper, Jaimie M Henderson, Cameron C. Mcintyre
    Abstract:

    Despite the clinical success of deep brain stimulation (DBS) for the treatment of movement disorders, many questions remain about its effects on the nervous system. This study presents a methodology to predict the volume of tissue activated (VTA) by DBS on a patient-specific basis. Our goals were to identify the intersection between the VTA and surrounding anatomical structures and to compare activation of these structures with clinical outcomes. The model system consisted of three fundamental components: (1) a 3D anatomical model of the subcortical nuclei and DBS electrode position in the brain, each derived from magnetic resonance imaging (MRI); (2) a finite element model of the DBS electrode and electric field transmitted to the brain, with tissue conductivity properties derived from diffusion tensor MRI; (3) VTA prediction derived from the response of myelinated axons to the applied electric field, which is a function of the stimulation parameters (contact, impedance, voltage, pulse width, frequency). We used this model system to analyze the effects of subthalamic nucleus (STN) DBS in a patient with Parkinson's disease. Quantitative measurements of bradykinesia, rigidity, and corticospinal tract (CST) motor thresholds were evaluated over a range of stimulation parameter settings. Our model predictions showed good agreement with CST thresholds. Additionally, stimulation through electrode contacts that improved bradykinesia and rigidity generated VTAs that overlapped the zona incerta/Fields of Forel (ZI/H2). Application of DBS technology to various neurological disorders has preceded scientific characterization of the volume of tissue directly affected by the stimulation. Synergistic integration of clinical analysis, neuroimaging, neuroanatomy, and neurostimulation modeling provides an opportunity to address wide ranging questions on the factors linked with the therapeutic benefits and side effects of DBS.

Christophe R Utso - One of the best experts on this subject based on the ideXlab platform.

  • anatomical targets associated with abrupt versus gradual washout of subthalamic deep brain stimulation effects on bradykinesia
    PLOS ONE, 2014
    Co-Authors: Sco E Coope, Cameron C. Mcintyre, Andre M. Machado, Klaus Driesslei, Angela M Noecke, Christophe R Utso
    Abstract:

    The subthalamic nucleus (STN) is a common anatomical target for deep brain stimulation (DBS) for the treatment of Parkinson’s disease. However, the effects of stimulation may spread beyond the STN. Ongoing research aims to identify nearby anatomical structures where DBS-induced effects could be associated with therapeutic improvement or side effects. We previously found that DBS lead location determines the rate – abrupt vs. gradual – with which therapeutic effect washes out after stimulation is stopped. Those results suggested that electrical current spreads from the electrodes to two spatially distinct stimulation targets associated with different washout rates. In order to identify these targets we used computational models to predict the volumes of tissue activated during DBS in 14 Parkinson’s patients from that study. We then coregistered each patient with a stereotaxic atlas and generated a probabilistic stimulation atlas to obtain a 3-dimensional representation of regions where stimulation was associated with abrupt vs. gradual washout. We found that the therapeutic effect which washed out gradually was associated with stimulation of the zona incerta and Fields of Forel, whereas abruptly-disappearing therapeutic effect was associated with stimulation of STN itself. This supports the idea that multiple DBS targets exist and that current spread from one electrode may activate more than one of them in a given patient, producing a combination of effects which vary according to electrode location and stimulation settings.

Christopher R. Butson - One of the best experts on this subject based on the ideXlab platform.

  • Anatomical Targets Associated with Abrupt versus Gradual Washout of Subthalamic Deep Brain Stimulation Effects on Bradykinesia
    2015
    Co-Authors: Scott E. Cooper, Klaus G. Driesslein, Angela M. Noecker, Cameron C. Mcintyre, Andre M. Machado, Christopher R. Butson
    Abstract:

    The subthalamic nucleus (STN) is a common anatomical target for deep brain stimulation (DBS) for the treatment of Parkinson’s disease. However, the effects of stimulation may spread beyond the STN. Ongoing research aims to identify nearby anatomical structures where DBS-induced effects could be associated with therapeutic improvement or side effects. We previously found that DBS lead location determines the rate – abrupt vs. gradual – with which therapeutic effect washes out after stimulation is stopped. Those results suggested that electrical current spreads from the electrodes to two spatially distinct stimulation targets associated with different washout rates. In order to identify these targets we used computational models to predict the volumes of tissue activated during DBS in 14 Parkinson’s patients from that study. We then coregistered each patient with a stereotaxic atlas and generated a probabilistic stimulation atlas to obtain a 3-dimensional representation of regions where stimulation was associated with abrupt vs. gradual washout. We found that the therapeutic effect which washed out gradually was associated with stimulation of the zona incerta and Fields of Forel, whereas abruptly-disappearing therapeutic effect was associated with stimulation of STN itself. This supports the idea that multiple DBS targets exist and that current spread from one electrode may activate more than one of them in a given patient, producin

  • patient specific analysis of the volume of tissue activated during deep brain stimulation
    NeuroImage, 2007
    Co-Authors: Christopher R. Butson, Scott E. Cooper, Jaimie M Henderson, Cameron C. Mcintyre
    Abstract:

    Despite the clinical success of deep brain stimulation (DBS) for the treatment of movement disorders, many questions remain about its effects on the nervous system. This study presents a methodology to predict the volume of tissue activated (VTA) by DBS on a patient-specific basis. Our goals were to identify the intersection between the VTA and surrounding anatomical structures and to compare activation of these structures with clinical outcomes. The model system consisted of three fundamental components: (1) a 3D anatomical model of the subcortical nuclei and DBS electrode position in the brain, each derived from magnetic resonance imaging (MRI); (2) a finite element model of the DBS electrode and electric field transmitted to the brain, with tissue conductivity properties derived from diffusion tensor MRI; (3) VTA prediction derived from the response of myelinated axons to the applied electric field, which is a function of the stimulation parameters (contact, impedance, voltage, pulse width, frequency). We used this model system to analyze the effects of subthalamic nucleus (STN) DBS in a patient with Parkinson's disease. Quantitative measurements of bradykinesia, rigidity, and corticospinal tract (CST) motor thresholds were evaluated over a range of stimulation parameter settings. Our model predictions showed good agreement with CST thresholds. Additionally, stimulation through electrode contacts that improved bradykinesia and rigidity generated VTAs that overlapped the zona incerta/Fields of Forel (ZI/H2). Application of DBS technology to various neurological disorders has preceded scientific characterization of the volume of tissue directly affected by the stimulation. Synergistic integration of clinical analysis, neuroimaging, neuroanatomy, and neurostimulation modeling provides an opportunity to address wide ranging questions on the factors linked with the therapeutic benefits and side effects of DBS.