Publications by authors named "Rens Verhagen"

Motor improvement after deep brain stimulation (DBS) in the subthalamic nucleus (STN) may vary substantially between Parkinson's disease (PD) patients. Research into the relation between improvement and active contact location requires a correction for anatomical variation. We studied the relation between active contact location relative to the neurophysiological STN, estimated by the intraoperative microelectrode recordings (MER-based STN), and contralateral motor improvement after one year.

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Background: Individual motor improvement after deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's disease (PD) varies considerably. Stereotactic targeting of the dorsolateral sensorimotor part of the STN is considered paramount for maximising effectiveness, but studies employing the midcommissural point (MCP) as anatomical reference failed to show correlation between DBS location and motor improvement. The medial border of the STN as reference may provide better insight in the relationship between DBS location and clinical outcome.

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Objective: Novel deep brain stimulation (DBS) lead designs are currently entering the market, which are hypothesized to provide a way to steer the stimulation field away from neural populations responsible for side effects and towards populations responsible for beneficial effects. The objective of this study is to assess the performances of a new eight channel steering-DBS lead and compare this with a conventional cylindrical contact (CC) lead.

Approach: The two leads were evaluated in a finite element electric field model combined with multicompartment neuron and axon models, representing the internal capsule (IC) fibers and subthalamic nucleus (STN) cells.

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This proof-of-principle study describes the methodology and explores and demonstrates the applicability of a system, existing of miniature inertial sensors on the hand and a separate force sensor, to objectively quantify hand motor symptoms in patients with Parkinson's disease (PD) in a clinical setting (off- and on-medication condition). Four PD patients were measured in off- and on- dopaminergic medication condition. Finger tapping, rapid hand opening/closing, hand pro/supination, tremor during rest, mental task and kinetic task, and wrist rigidity movements were measured with the system (called the PowerGlove).

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Cortical involvement in essential tremor, an involuntary action tremor supposedly of subcortical origin, is uncertain. Conflicting results of corticomuscular coherence studies in essential tremor suggest an intermittent corticomuscular coupling. On the basis of the literature, we hypothesized that corticomuscular coupling is influenced by bilateral motor synchronization and "cognitive states" such as awareness of tremor.

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Objective: The correspondence between the anatomical STN and the STN observed in T2-weighted MRI images used for deep brain stimulation (DBS) targeting remains unclear. Using a new method, we compared the STN borders seen on MRI images with those estimated by intraoperative microelectrode recordings (MER).

Approach: We developed a method to automatically generate a detailed estimation of STN shape and the location of its borders, based on multiple-channel MER measurements.

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Background: In deep brain stimulation of the subthalamic nucleus (STN-DBS) for Parkinson's Disease (PD), often microelectrode recordings (MER) are used for STN identification. However, for advanced target identification of the sensorimotor STN, it may be relevant to use local field potential (LFP) recordings. Then, it is important to assure that the measured oscillations are coming from the close proximity of the electrode.

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Objective: The clinical effects of deep brain stimulation (DBS) of the subthalamic nucleus (STN-DBS) as a treatment for Parkinson's disease are sensitive to the location of the DBS lead within the STN. New high density (HD) lead designs have been created which are hypothesized to provide additional degrees of freedom in shaping the stimulating electric field. The objective of this study is to compare the performances of a new HD lead with a conventional cylindrical contact (CC) lead.

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Objective: The aim of this study was to investigate whether directional steering through a novel 32-contact electrode is safe and can modulate the thresholds for beneficial and side effects of stimulation.

Methods: The study is a single-center, performance and safety study. Double-blind intraoperative evaluations of the thresholds for therapeutic benefit and for side effects were performed in 8 patients with Parkinson disease while stimulating in randomized order in spherical mode and in 4 different steering modes with the 32-contact electrode, and in monopolar mode with a commercial electrode.

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Objective: Assessment of event-related desynchronization (ERD) may assist in predicting recovery from stroke and rehabilitation, for instance in BCI applications. Here, we explore the temporal evolution of ERD during stroke recovery.

Methods: Ten stroke patients and eleven healthy controls were recruited to participate in a hand movement task while EEG was being recorded.

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Article Synopsis
  • The study investigates how different baseline conditions affect the mu-rhythm in the brain during motor imagery tasks.
  • It involved 18 healthy participants who performed tasks while their EEG was recorded, using five distinct baseline videos.
  • Results showed that about 50% of participants had high mu-power with specific baselines, while 67% displayed a contralateral ERD, highlighting the importance of baseline selection for accurately measuring brain activity.
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