Neuromodulation : journal of the International Neuromodulation Society
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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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Objectives. Traditional deep brain stimulation (DBS) at the subthalamic nucleus (STN) has proved to be efficacious on core Parkinsonian symptoms. However, very disabling l-dopa-induced abnormal involuntary movements (AIMs) and axial signs are slightly affected, suggesting that we target less conventional targets. Our candidates for DBS were the globus pallidus internus (GPi) plus the intralaminar thalamic complex (Pf or CM), given its extensive functional links with basal ganglia nuclei. ⋯ CM-Pf activation was only slightly effective in reducing rigidity and akinesia, but more efficacious on freezing. Not surprisingly, AIMs were peculiarly decreased by the activation of the permanent electro-catheter in the posteroventral GPi. Conclusions. These findings confirm that, in selected patients, it is conceivable to target structures other than the conventional STN in order to maximize clinical benefit.
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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.