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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 1887-1897 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An electromyography (EMG) system is presented that noninvasively records the electrical activity of a muscle with 126 densely spaced skin-surface electrodes. The electrodes are arranged in a two-dimensional array and integrated in a single container for ease of application. Signals are recorded "monopolarly", with a reference electrode placed at a distance from the array. With this recording configuration, the surface EMG (sEMG) potential distribution can be described not only as a function of time, but also topographically. The availability of topographical information opens up a range of applications. Some of these have been described previously. However, the system presented is unique in that it allows exploration of all clinical and scientific possibilities of topographical sEMG. In its design, special attention was paid to user-friendliness and flexibility. With high-density multichannel sEMG, both the properties of a whole muscle and those of single motor units, the functional units of a muscle, can be studied. The latter belong to a realm that was long considered accessible only with needle-EMG, a conventional, invasive diagnostic technique. It is demonstrated that the additional topographical information can be used to characterize motor units in a way that is partially superior to needle EMG. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Anaesthesia 52 (1997), S. 0 
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Thirteen patients were monitored for nocturnal body position (supine vs. side) and arterial oxygen saturation pre-operatively and on the second postoperative night after major abdominal surgery. The number of positional changes were significantly decreased after operation (p 〈 0.05) with a trend towards more time spent in the supine position (p = 0.1). Individual mean arterial oxygen saturation decreased postoperatively (p 〈 0.05) but without a difference between the supine and side positions (p = 0.9). Pre-operatively, episodic desaturations were significantly more frequent in the supine position than on the side (p 〈 0.05) but not postoperatively. Pain was the most frequent reason for decreased nocturnal movements.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 233 (1986), S. 25-29 
    ISSN: 1432-1459
    Keywords: Ballism, bilateral ; Aetiology ; Pathological substrate ; Dopamine antagonists
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ballism rarely occurs as a bilateral phenomenon and only 12 such cases have been reported so far in the literature. A further case is reported in the present paper. The definition of bilateral ballism is discussed, its movements described and the differences from chorea outlined. The most important difference from hemiballism is in the pathological substrate where, in most bilateral cases, diffuse lesions have been reported on both sides of the basal ganglia, without preferential involvement of the subthalamic nucleus. In our case, a frontotemporal infarction was found. In the cases reported to date, the outcome had varied from death to complete recovery, partly depending on the aetiology, which is most frequently vascular. Although relevant data are scarce, dopamine antagonists appear to be the treatment of choice. We stress the role of the dopaminergic system and co-existing factors influencing the abnormal involuntary movements.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 58 (1988), S. 278-283 
    ISSN: 1439-6327
    Keywords: Muscle fiber conduction velocity ; Local muscle fatigue ; Force ; Intramuscular circulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two series of experiments were performed to examine the relationship between force and change in average musle fibre conduction velocity (MFCV) during local muscle fatigue. The average MFCV was estimated using the cross-correlation method. In the first experiment this relationship was studied with surface EMG of vastus lateralis at force levels from 10 to 100% of maximal voluntary contraction (MVC) with and without occluded circulation. The product of relative force and time was held constant. At 10–20% MVC, MFCV increased slightly under the 2 conditions. Between 30–40% MVC, MFCV decreased, this decline in conduction velocity being significantly greater with occluded circulation. Above 40% MVC the decline in MFCV was larger at higher forces, but without any difference between the ischaemic and non-ischaemic conditions. In the second experiment the relationship between change in force and MFCV was studied during sustained maximal voluntary contractions of biceps brachii. MFCV declined during the first 26–39 s of the contraction, followed by an increase. Since this increase occurred when the force had dropped to 30–50% of the initial maximal force, a partial restoration of blood flow is thought to be responsible for this phenomenon. Because an increase in MFCV was noted, despite a further decline in force, this implies that at high force levels the change in MFCV during fatigue could partly be caused by mechanisms different from those accounting for the force loss. It is concluded that above 40% MVC intramuscular pressure is sufficiently high to cause ischaemia, and MFCV is found to be very sensitive to changes in intramuscular blood flow.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1439-6327
    Keywords: Muscle fibre conduction velocity ; EMG power spectral shift ; Muscular fatigue ; Recovery ; Ischaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The relationship between muscle fibre conduction velocity (MFCV) and the power spectrum of surface EMGs in 3 human volunteers was studied during isometric contractions at 40% maximum voluntary contraction. In addition, the recovery of these two parameters was measured during short lasting contractions at the same force level every 30 s. The recovery phase was also studied during ischaemia, thereby preventing the recovery of MFCV. The mean MFCV was calculated by the cross-correlation method. The measurements were facilitated by a real-time estimation of the cross-correlation and the MFCV and by a graphic display of the digitised signal. During contraction a nearly linear relation was found between MFCV and the median frequency of the power spectrum (MPF). During recovery this relationship was lost in one subject: MPF restored much faster then MFCV. During recovery under ischemia MFCV did not recover, but MPF recovered partially in all subjects. It is concluded that the shift of the power spectrum to lower frequencies during fatigue cannot be explained by changes in MFCV alone. Central mechanisms also influence the power spectrum and studying the recovery of local muscle fatigue during ischemia may separate these influences from that of MFCV on the power spectrum during fatigue.
    Type of Medium: Electronic Resource
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