Neuromodulation : journal of the International Neuromodulation Society
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Objective. The outcomes of different modes of TENS (transcutaneous electrical nerve stimulation) in relieving experimental heat and cold pain were studied. Materials and methods. Three modes of stimulation, conventional, burst, and high rate frequency modulation (HRFM) including placebo, were trancutaneously applied to 20 right handed healthy volunteers (10 males and 10 females). Stimulation was carried out using two pad electrodes placed over the median nerve for 120 s in each case. ⋯ Conclusions. All modes of stimulation statistically decreased both heat and cold pain when compared to placebo. HRFM was the most effective mode of TENS. It might be worthwhile to test the patterns of stimulation in chronic pain patients.
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The performance of cathode-anode configurations in a cuff electrode to stimulate a single fascicle in a nerve trunk has been investigated theoretically. A three-dimensional volume conductor model of a nerve trunk with four fascicles in a cuff electrode and a model of myelinated nerve fiber stimulation were used to calculate the recruitment of 15 m fibers in each fascicle. The effect of a monopole, a transverse bipole (anode opposite the cathode), and a narrow transverse tripole (guarded cathode) in selectively stimulating 15 m fibers in each fascicle has been quantified and presented as recruitment curves. ⋯ As compared to monopolar and longitudinal tripolar stimulation, the slope of the recruitment curves in transverse bipolar stimulation is reduced considerably, thus allowing improved fine tuning of nerve (and thus force) recruitment. Another advantage of this method is a minimal number of cable connections to the cuff electrode. The cost of the improved selectivity is an increased stimulation current.
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Percutaneous epidural neuroplasty (lysis of epidural adhesions, epidural application of hypertonic saline) is an interventional technique for the management of pain due to spinal disorders. Epidural neuroplasty is found to be effective in removing fibrous tissue occurring in the epidural space for various reasons, however, the procedure may be prone to serious complications. We present here our retrospectively collected complications and precautions of complications of epidural neuroplasty in 250 patients. ⋯ Possible known complications include bending of the tip of the introducer needle, shearing/tearing of the catheter, misplacement of the catheter, inadvertent blockage of the catheter or catheter tip, migration of the catheter, hypotension, respiratory depression, urinary and/or fecal incontinence, urinary hesitancy, sexual dysfunction, paresthesia, epidural abscess, and meningitis. We found the following complications in our series: the tips of the introducer needle were bent in 12 patients; catheter sheaths were torn during withdrawal through the needle in three patients; 39 patients had bleeding or aspiration of blood from the epidural space; eight patients had their catheters migrate into an epidural vein; one patient's catheter migrated into the prevertebral space during the procedure; there were dural punctures in 11 patients; there were catheter blockages in six patients during consecutive applications of neuroplasty; hypotension was seen during and after drug injections in 12 patients, there was hypotension in one patient; three patients had migration and penetration of their catheters into the dura after placement and in consecutive days; 25 patients experienced numbness in dermatomal areas of the upper and lower extremities depending the level of the procedure; and there were eight infections at the entry site of the catheter, three epidural abscesses, and two patients with meningitis. In order to prevent complications such as those seen, epidural neuroplasty procedures must be performed in well-equipped centers by experienced hands.
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The aim of this study was to investigate the causation of an insufficient clinical response to acute external stimulation after implantation of brain stimulating electrodes in patients with idiopathic Parkinson's disease (IPD). This study represents to our knowledge the first consecutive postoperative monitoring of the electrical properties of electrodes and tissue in this patient cohort. We hypothesized that changes in brain tissue resistance would be etiologic for this clinically observed phenomenon. ⋯ The changes of the voltage drop on the electrodes and the tissue were insignificant over the time course. We conclude that the decline of the clinical benefit is not due to an alteration of tissue resistivity. As an explanation, we postulate that the reactive formation/resolution of edema around the electrode has the same resistivity as the target and is therefore not detectable by our measurements or modulated by a still unknown mechanism.