Neuromodulation : journal of the International Neuromodulation Society
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Introduction. Spinal cord stimulation (SCS) is an effective procedure for the treatment of neuropathic extremity pain, with success rates approaching 70%. However, mechanical failures, including breakage and migration, can significantly limit the long-term effectiveness of SCS. A systematic analysis of surgical techniques was undertaken by a consensus group, coupled with extensive in vivo and in vitro biomechanical testing of system components. ⋯ Based on these findings, the panel recommended a paramedian approach, abdominal pulse generator placement, maximizing bend radius by pushing the anchor through the fascia, and anchoring of the extension connector near the lead anchor. Discussion. Several factors are important in longevity of SCS systems. We discovered that technical factors can make a large difference in SCS reliability and that strict attention to these "best practices" will provide the best chance for maintaining the integrity of SCS systems over the long term.
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Objectives. Spinal cord stimulation (SCS) is an effective treatment option for chronic radicular neuropathic pain syndromes. This prospective study was performed to examine the peripheral effects of SCS on sensation using quantitative sensory testing (QST). Materials and Methods. We measured two consecutive QST measurements for thermal, tactile-static, tactile-dynamic, vibratory, and pain sensation of the lower limbs in seven patients with chronic unilateral radicular neuropathic pain who underwent SCS implantation for their pain. ⋯ Although not significant (p > 0.01), altered sensory thresholds with active SCS also were found at the healthy side where no paresthesias were felt. Conclusion. SCS leads to bilateral subclinical effects even if the evoked paresthesias are only unilateral. Pain perception thresholds are not altered with therapeutic SCS.
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Objectives. To evaluate magnetic resonance imaging-related (MRI-related) heating for the VNS Therapy System at 1.5 and 3 tesla (T) using various device configurations and MRI conditions and to assess device function before and after MRI. Methods. The VNS Therapy System (pulse generator, Model 102; leads Models 300 and 302; Cyberonics, Inc., Houston, Tex, USA) underwent assessment of MRI-related heating at 1.5 and 3 T using different positioning configurations, leads, transmit radiofrequency (RF) coils (body and head), RF power levels, and scans on different body regions. The function of the VNS Therapy System was evaluated before and after scanning. ⋯ Conclusions. MRI-related heating was characterized for a variety of scenarios, identifying unsafe as well as safe conditions. Device function was unaffected by MRI procedures at 1.5 and 3 T. By following specific conditions, safety guidelines for the VNS Therapy System may be expanded beyond those currently indicated by the manufacturer.
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Experienced neurosurgeons at eight spinal cord stimulation centers in the United States, Canada, and Europe participated in a study from 1997 to 2000 investigating the safety, performance, and efficacy of a Transverse Tripolar Stimulation (TTS) system invented at the University of Twente, the Netherlands. This device was proposed to improve the ability of spinal cord stimulation to adequately overlap paresthesia to perceived areas of pain. Fifty-six patients with chronic, intractable neuropathic pain of the trunk and/or limbs more than three months' duration (average 105 months) were enrolled with follow-up periods at 4, 12, 26, and 52 weeks. ⋯ The most common complication was lead migration. While the transverse stimulation system produced acceptable outcomes for overall pain relief, an analysis of individual pain patterns suggests that it behaves like spinal cord stimulation in general with the best control of extremity neuropathic pain. This transverse tripole lead and driving system introduced the concept of electrical field steering by selective recruitment of axonal nerve fiber tracts in the dorsal columns.
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Objectives. There is ample and well-established evidence that direct electrical stimulation of the vagus nerve can change heart rate in animals and humans. Since tachyarrhythmias cannot always be controlled through medication, we sought, in this pilot study, to elucidate whether a clinical implantable lead system that is used in cervical vagus nerve stimulation therapy (VNS therapy) also can be used for control of heart rate, and tachycardia in particular. Materials and Methods. Experiments were carried out in three pigs (weight 21-26 kg) under general anesthesia. ⋯ No differences were found between stimulation of the right or left vagus nerve. Conclusion. VNS can be used effectively and rapidly to decrease heart rate, in acute settings, when connected to an external pacing system. Future devices that are fully implantable may be used for nonpharmacological treatment of illnesses in which tachycardia results in deterioration of cardiac function.