Neuromodulation : journal of the International Neuromodulation Society
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This paper reviews data supporting the existence of individual, predictable, and unpredictable fluctuations in the severity of chronic pain and spasticity. It also evaluates what is known on the use of implantable programmable drug delivery systems for the management of predictable fluctuations in pain and spasticity. In addition to fixed rate infusion pumps, programmable drug delivery systems have been developed over the past 20 years for the management of predictable pain or spasticity fluctuations. ⋯ Ideally, the patient should be able to treat unpredictable fluctuations in symptoms, and a combination of patient controlled analgesia (PCA) with programmable drug delivery systems is currently in development. The future management of unpredictable fluctuations in the intensity of chronic pain and spasticity was subjected to critical evaluation. There seems to be a general agreement on the clinical importance of these phenomena, but stronger evidence is needed for a widespread change in the current management of most chronic pain patients.
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The purpose of this study was to investigate the short-term history effect of a decreasing frequency train on force and the influence of joint angle on such effect in human dorsiflexor muscles. Six able-bodied and three spinal cord injured (SCI) subjects took part in the study. Their isometric left dorsiflexor muscles were stimulated with two-second bursts at three ankle joint positions and movements at the ankle were measured. ⋯ This was true for all the subjects at dorsiflexed positions, but the effect is highly dependent on joint ankle. At plantar flexed positions moment enhancement was seen only in SCI subjects. We conclude that effects of joint angle as well as individual muscle properties should be taken into account when optimizing muscle force by means of frequency modulation.
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The calculation of the parameters of the pump is complicated for a mixture of two drugs in continuous intrathecal therapy with implantable and programmable pumps. It is important to determine the best proportion of drug solutions to obtain the desired clinical results and also to adapt their proportion to obtain the maximal volume of solution so that the time between two fillings is maximized. This paper proposes mathematical formulas that make easier and faster the calculation of the flow of the pump, the volume of each drug solution to be added to the pump, the concentration of each drug in the mixture, and the duration of the infusion. ⋯ The calculated values cannot be directly applied because the syringes used to measure the volume of each drug solution have limited accuracy. It is necessary to round the volume of each drug solution and to hold their sum equal to the total volume of the reservoir. All the parameters are then recalculated, and the physician has to choose between several combinations of volumes.