Publications by authors named "Nico J M Rijkhoff"

In this simulation study, a wireless passive LC-tank sensor system was characterized. Given the application of continuous bladder monitoring, a specific system was proposed in terms of coil geometries and electronic circuitry. Coupling coefficients were spatially mapped by simulation, as a function of both coil distance, and longitudinal and transverse translation of the sensor relative to the antenna.

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Article Synopsis
  • The study examined how fibrous encapsulation impacts the electrochemical properties of porous titanium nitride electrodes in a living organism (in vivo).
  • Electrochemical impedance spectroscopy (EIS) was used to monitor inflammation and healing, revealing that the encapsulation lasted 3-4 weeks, during which voltage transients (VTs) increased and charge storage capacity (CSC) decreased.
  • The findings suggest that the changes in VTs and CSC are linked to the healing process, and that traditional methods may underestimate the limits of charge injection during encapsulation.
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Objectives: To evaluate the effect of subject-controlled, on-demand, dorsal genital nerve (DGN) stimulation on non-neurogenic urgency urinary incontinence (UUI) in a domestic setting.

Materials And Methods: Non-neurogenic patients >18 years with overactive bladder symptoms and UUI were included. Exclusion criteria were mainly stress urinary incontinence.

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The in vivo electrochemical behavior of titanium nitride (TiN) nerve stimulation electrodes was compared to their in vitro behavior for a period of 90 days. Ten electrodes were implanted in two Göttingen minipigs. Four of these were used for electrical stimulation and electrochemical measurements.

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Aims: To investigate the effects of subject controlled dorsal genital nerve (DGN) electrical stimulation on neurogenic detrusor overactivity (NDO) in subjects at home.

Methods: Subjects underwent a 5-day study at home with DGN stimulation. Stimulation was provided with surface electrodes placed either on the dorsal penile shaft in males and on or close to the clitoris in females.

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This study evaluates the outcome of trials to stimulate the dorsal genital nerve (DGN) in patients with lower urinary tract dysfunction. The aim of most studies was to suppress detrusor overactivity in patients with overactive bladder (OAB) syndrome by DGN stimulation. A literature search was performed using Pub Med, Web of Science, and Scopus databases (1980 to April 2012) for clinical trials of DGN stimulation in patients with detrusor overactivity.

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A single cuff electrode with multiple-contacts permits fibre selective recording from peripheral nerves. This has been demonstrated in frog nerve in vitro and earth worm before. In this paper we apply this method successfully to the peripheral median nerve of pig in vivo.

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Background: Tracking an ingested magnet by the Magnet Tracking System MTS-1 (Motilis, Lausanne, Switzerland) is an easy and minimally-invasive method to assess gastrointestinal transit. The aim was to test the validity of MTS-1 for assessment of gastric transit time and small intestinal transit time, and to illustrate transit patterns detected by the system.

Methods: A small magnet was ingested and tracked by an external matrix of 16 magnetic field sensors (4 × 4) giving a position defined by 5 coordinates (position: x, y, z, and angle: θ, φ).

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Purpose: The anatomy of the pudendal nerve and its nerve branches, especially the dorsal nerve of the penis and clitoris (dorsal genital nerves), and the clinical application of electrical stimulation of these nerves in patients with overactive bladder syndrome and detrusor overactivity are reviewed.

Materials And Methods: A literature search was performed using the PubMed® database and reference lists of relevant studies to obtain articles concerning the anatomy as well as the electrical stimulation of the pudendal nerve and its nerve branches in patients with overactive bladder syndrome.

Results: According to the anatomy, electrical stimulation of the pudendal nerve and the dorsal genital nerves to suppress involuntary detrusor contractions is possible at several sites along their course from the sacral nerves to the penis or clitoris.

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Purpose: Electrical sacral anterior root stimulation with a selective anodal block may relieve difficulties with bowel evacuation by selective colorectal activation and anal sphincter suppression. This study compares rectal evacuation induced by anodal block with that induced by unselective stimulation.

Methods: The sacral anterior roots were stimulated with cuff electrodes in seven chloralose-anesthetized minipigs.

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Purpose: Pelvic nerve stimulation evokes a complex motility response in the pig rectum with a proximal decrease and a distal increase in cross-sectional area. This study investigated whether the distal increase in the cross-sectional area is because of smooth muscle relaxation mediated by nitric oxide.

Methods: The pelvic nerves were stimulated with cuff electrodes in ten chloralose-anesthetized minipigs.

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The aim of this study was to investigate the feasibility of using external urethral sphincter electromyogram (EMG) (EUSEMG) to detect the onset of detrusor contractions in patients with both neurogenic detrusor overactivity (NDO) and detrusor sphincter dyssynergia (DSD). Detrusor pressure (Pdet) and EUSEMG was recorded in 23 neurogenic patients during slow artificial bladder filling. The time delay between the onset of a detrusor contraction and the onset of EUSEMG activity was calculated together with the detrusor pressure increase related to this delay.

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Objectives: The aim of this study was to investigate whether acute electrical stimulation of the posterior tibial nerve could suppress detrusor contractions in multiple sclerosis (MS) patients with neurogenic detrusor overactivity.

Methods: Two successive slow-fill cystometries (16 ml/min) were carried out in eight MS patients with neurogenic detrusor overactivity. The first filling served as control without stimulation.

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Electrical stimulation could be used to induce colon emptying. The present experiments were performed to establish a stimulation pattern to optimize the stimulation parameters and to test neural involvement in propulsion induced by electrical stimulation. Colon segments were sequentially stimulated using rectangular pulses.

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The present experiments were performed on rat colon to study neurogenic and myogenic elicited propulsion induced by 0.3 and 30 msec long current pulses. The colon segments were stimulated sequentially and randomly.

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Electrical stimulation of the colon can improve transit in slow-transit constipation, or enable controlled emptying in colostomy patients. Preliminary studies showed that sequential stimulation of consecutive colon segments induced serial contractions resulting in colonic propulsion. This study was performed to optimize the stimulation parameters.

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Electroneurographic signals were intraoperatively recorded from the S3 sacral nerve root in two SCI patients. The aim of this study was to record afferent nerve signals in response to mechanical stimulation of the urinary bladder, rectum, and dermatome. Such signals could be used in an implantable neuroprosthesis to treat neurogenic detrusor overactivity.

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The aim of this study was to investigate whether it is possible to reduce a charge per pulse, which is needed for selective nerve stimulation. Simulation is performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a human fiber model to simulate the fiber response to simulation. Selective stimulation is obtained by anodal block.

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Background: Neural prostheses are a technology that uses electrical activation of the nervous system to restore function to individuals with neurological or sensory impairment.

Introduction: This article provides an introduction to neural prostheses and lists the most successful neural prostheses (in terms of implanted devices).

Current Treatment: The article then focuses on neurogenic bladder dysfunction and describes two clinically available implantable neural prostheses for treatment of neurogenic bladder dysfunction.

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Electrical stimulation of peripheral nerves can be used to cause muscle contraction, to activate reflexes, and to modulate some functions of the central nervous system (neuromodulation). If applied to the spinal cord or nerves controlling the lower urinary tract, electrical stimulation can produce bladder or sphincter contraction, produce micturition, and can be applied as a medical treatment in cases of incontinence and urinary retention. This article first reviews the history of electrical stimulation applied for treatment of bladder dysfunction and then focuses on the implantable Finetech-Brindley stimulator to produce bladder emptying, and on external and implantable neuromodulation systems for treatment of incontinence.

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