Neuromodulation : journal of the International Neuromodulation Society
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Ever since its initial development in the late 1960s, spinal cord stimulation (SCS) has been used to treat a number of painful conditions. European practice, in contrast to that in North America, has used peripheral arterial disease (PAD) as a primary indication for SCS. First employed in patients with PAD in 1976, SCS was shown by Cook et al. to heal chronic leg ulcers. ⋯ Recent randomized prospective studies have questioned some of the conclusions from these preceding retrospective data. In addition to the questions related to outcomes, theories regarding exact mechanisms by which SCS improves circulatory parameters remain unclear. A thorough Medline literature review on the subject of SCS in peripheral vascular disease was thus undertaken to attempt to clarify questions regarding which patients are best suited for SCS therapy, pinpoint possible methodologic flaws in previous studies, and to review the background, outcomes, mechanisms of action, complications, and alternatives for SCS in patients with PAD.
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The objective of this study was to investigate di-acetyl morphine as an alternative opioid analgesic for use in implanted intrathecal drug delivery systems because of its greater solubility through evaluation of its stability in vivo and analgesic efficacy in the period between pump refills. Contents of intrathecal drug delivery system reservoirs (SynchroMed, Medtronic, Inc., Minneapolis, MN) that had been filled with di-acetyl morphine dissolved in saline (21), bupivacaine (9), or in both bupivacaine and clonidine (19) were sampled in vivo between 1 and 125 days after refill. The samples were assayed for di-acetyl morphine and its breakdown products by micellar electrokinetic capillary chromatography. ⋯ Mono-acetyl morphine decayed to morphine with a maxima estimated at 125 days. There was no clinically significant change in average weekly pain scores for up to ten weeks in either group (range, 2.5 to 2.8 for diamorphine and 2.7 to 3.1 for morphine) (2-way repeated ANOVA, F(9,220) = 0.98, n.s.). We conclude that di-acetyl morphine and its breakdown products, 6 mono-acetyl morphine and morphine, provide similar analgesia to morphine alone when administered by intrathecal pump for a period of at least ten weeks and may be a useful alternative when a more soluble agent is favored.
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This study investigated the activation dynamics of electrical stimulation-evoked muscle contractions performed by individuals with spinal cord injury (SCI). The purpose was to determine whether electrical stimulation (ES) firing patterns during cycling exercise should be altered in response to fatigue-induced changes in the time taken for force to rise and fall with ES. Seven individuals with SCI performed isometric contractions and pedaled a motorized cycle ergometer with stimulation applied to the quadriceps muscles. ⋯ Cycling power output fell approximately 50% during the five minutes of exercise, however, there was no change in the time taken for torque to rise or fall. The magnitude of ES-evoked muscle torques decline substantially with fatigue, however, the overall pattern of torque production remained relatively unchanged. These results suggest there is no need to alter stimulation firing patterns to accommodate fatigue during ES-evoked exercise.
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The objective of this study is to determine the usefulness of single-patient, randomised, controlled trials (N-of-1 trials) in assessing the efficacy of deep brain stimulation (DBS) in neuropathic pain. Seven patients with various causes of intractable neuropathic pain underwent insertion of deep brain stimulating electrodes into the periventricular gray area or ventroposterolateral nucleus of the thalamus. Preoperatively, pain was measured using Visual Analog Scales (VAS) and the McGill Pain Questionnaire (MPQ). ⋯ The results of the N-of-1 trials were most similar to the MPQ scores and showed that three of seven patients could accurately predict whether the DBS was on or off. In the N-of-1 trials, the time between changing the DBS from on to off (or vice versa) had an effect on the results and probably underestimated the efficacy. We conclude that N-of-1 trials are a useful tool for assessing DBS efficacy.