Machiel J. Zwarts

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Retrieval of recently acquired declarative memories depends on the hippocampus, but with time, retrieval is increasingly sustainable by neocortical representations alone. This process has been conceptualized as system-level consolidation. Using functional magnetic resonance imaging, we assessed over the course of three months how consolidation affects the(More)
In this study, we compared the sensitivity and specificity of visual versus quantitative evaluation of skeletal muscle ultrasound in children suspected of having a neuromuscular disorder (NMD). Ultrasonography (US) scans of four muscles (biceps brachii, forearm flexors, quadriceps femoris, anterior tibial muscle) were made in 76 children. All images were(More)
OBJECTIVE To collect and integrate existing data concerning the occurrence, extent, time course, and prognostic determinants of motor recovery after stroke using a systematic methodologic approach. DATA SOURCES A computer-aided search in bibliographic databases was done of longitudinal cohort studies, original prognostic studies, and randomized controlled(More)
OBJECTIVE To assess the prevalence of severe fatigue and its relation to functional impairment in daily life in patients with relatively common types of neuromuscular disorders. METHODS 598 patients with a neuromuscular disease were studied (139 with facioscapulohumeral dystrophy, 322 with adult onset myotonic dystrophy, and 137 with hereditary motor and(More)
BACKGROUND Botulinum toxin type A (BTA) is replacing trihexyphenidyl as the treatment of choice for idiopathic cervical dystonia (ICD), but there has never been a direct comparative study. METHODS This trial compares the effectiveness of BTA with that of trihexyphenidyl in a prospective, randomized, double-blind design. Sixty-six consecutive patients with(More)
OBJECTIVE The primary aim of this study was to compare the predictive value of motor evoked potentials (MEPs) and early clinical assessment with regard to long-term hand motor recovery in patients with profound hemiplegia after stroke. METHODS The sample was an inception cohort of 39 stroke patients with an acute, ischemic, supratentorial stroke and an(More)
Ultrasonography can detect structural muscle changes caused by neuromuscular disease. Quantitative analysis is the preferred method to determine if ultrasound findings are within normal limits, but normative data are incomplete. The purpose of this study was to provide normative muscle ultrasonography data for muscle thickness and echo intensity for five(More)
Measurements were done on the biceps muscles of 6 healthy volunteers to record simultaneously the surface electromyogram (EMG) and vibromyogram (VMG) by means of a piezoelectric device (accelerometer). The VMG is generated by mechanical waves due to the contraction mechanism and often measured as sound. The frequency spectrum and integrated value (IEMG and(More)
Muscle ultrasound is a useful tool in the diagnosis of neuromuscular disorders, as these disorders result in muscle atrophy and intramuscular fibrosis and fatty infiltration, which can be visualized with ultrasound. Several prospective studies have reported high sensitivities and specificities in the detection of neuromuscular disorders. Although not(More)
The generation of the surface electromyogram (sEMG) is described with regard to the properties of the single muscle fiber action potential as source, the physical aspects of volume conduction and recording configuration, and the properties and firing pattern of motor units (MUs). The spatial aspect of the motor unit action potential (MUP) is emphasized in(More)