Perception threshold and electrode position for spinal cord stimulation

The perception threshold for epidural spinal cord stimulation in chronic pain management was analyzed on 3923 testing data obtained from 136 implanted patients. The initial areas of paresthesiae due to stimulation were recorded and reported as the stimulation map according to the location of electrodes. Measurement of dorsal thickness of the cerebrospinal fluid (CSF) layer was obtained from 26 subjects using magnetic resonance imaging (MRI). The results indicate that the perception threshold is a function of the spinal level of the implanted electrodes, of the mediolateral position in the spinal canal and the contact separation of electrode. Differences in perception threshold at various vertebral levels are mainly due to varying depths of the dorsal CSF layer. The medially placed electrodes caudal to the mid-cervical levels have a higher perception threshold than more laterally placed ones. The electrodes at high and mid-cervical levels, however, have a smaller perception threshold if placed medially. The information obtained from this investigation has important implications for the design of a new-generation stimulation system and clinical application to maximize the longevity of the power source

Paresthesia thresholds in spinal cord stimulation: a comparison of theoretical results with clinical data

The potential distributions produced in the spinal cord and surrounding tissues by dorsal epidural stimulation at the midcervical, midthoracic, and low thoracic levels were calculated with the use of a volume conductor model. Stimulus thresholds of myelinated dorsal column fibers and dorsal root fibers were calculated at each level in models in which the thickness of the dorsal cerebrospinal fluid (CSF) layer was varied. Calculated stimulus thresholds were compared with paresthesia thresholds obtained from measurements at the corresponding spinal levels in patients. The influences of the CSF layer thickness, the contact separation in bipolar stimulation and the laterality of the electrodes on the calculated thresholds were in general agreement with the clinical dat

Primary 3-Month Outcomes of a Double-Blind Randomized Prospective Study (The QUEST Study) Assessing Effectiveness and Safety of Novel High-Frequency Electric Nerve Block System for Treatment of Post-Amputation Pain

Leonardo Kapural,1 Jim Melton,2 Billy Kim,3 Priyesh Mehta,4 Abindra Sigdel,5 Alexander Bautista,6 Erika A Petersen,7 Konstantin V Slavin,8,9 John Eidt,10 Jiang Wu,11 Said Elshihabi,12 Jason Matthew Schwalb,13 H Edward Garrett Jr,14 Elias Veizi,15 Giancarlo Barolat,16 Ravi R Rajani,17 Peter C Rhee,18 Maged Guirguis,19 Nagy Mekhail20 1Carolinas Pain Institute and Center for Clinical Research, Winston-Salem, NC, USA; 2Department of Vascular Surgery, Cardiovascular Health Clinic, Oklahoma City, OK, USA; 3Department of Vascular Surgery, The Surgical Clinic, Nashville, TN, USA; 4Department of Pain Medicine, Meta Medical Research Institute, Dayton, OH, USA; 5Department of Surgery, University of Louisville, Louisville, KY, USA; 6Department of Anesthesiology and Perioperative Medicine, University of Louisville, Louisville, KY, USA; 7Department of Neurosurgery, University of Arkansas, Little Rock, AR, USA; 8Department of Neurosurgery, University of Illinois at Chicago, Chicago, IL, USA; 9Department of Neurology, Jesse Brown VA Medical Center, Chicago, IL, USA; 10Department of Vascular Surgery, Baylor Scott and White Heart and Vascular Hospital Dallas, Dallas, TX, USA; 11Department of Anesthesiology & Pain Medicine, University of Washington Medical Center, Seattle, WA, USA; 12Department of Neurosurgery, Legacy Brain & Spine Surgical Center, Atlanta, GA, USA; 13Department of Neurosurgery, Henry Ford Medical Group, Detroit, MI, USA; 14Department of Vascular Surgery, University of Tennessee-Memphis, Memphis, TN, USA; 15Department of Pain Medicine, VA Northeast OH Healthcare System, Cleveland, OH, USA; 16Department of Neurosurgery, Barolat Neuroscience, Presbyterian/St Luke’s Medical Center, Denver, CO, USA; 17Department of Vascular Surgery, Emory University and Grady Memorial Hospital, Atlanta, GA, USA; 18Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; 19Department of Interventional Pain Management, Ochsner Health System, New Orleans, LA, USA; 20Department of Pain Management, Cleveland Clinic, Cleveland, OH, USACorrespondence: Leonardo Kapural, Carolinas Pain Institute and Center for Clinical Research, 145 Kimel Park Dr #330, Winston-Salem, NC, 27103, USA, Email [email protected]: This multicenter, randomized, double-blinded, active sham-controlled pivotal study was designed to assess the efficacy and safety of high-frequency nerve block treatment for chronic post-amputation and phantom limb pain.Patients and Methods: QUEST enrolled 180 unilateral lower-limb amputees with severe post-amputation pain, 170 of whom were implanted with the Altius device, were randomized 1:1 to active-sham or treatment groups and reached the primary endpoint. Responders were those subjects who received ≥ 50% pain relief 30 min after treatment in ≥ 50% of their self-initiated treatment sessions within the 3-month randomized period. Differences between the active treatment and sham control groups as well as numerous secondary outcomes were determined.Results: At 30-min, (primary outcome), 24.7% of the treatment group were responders compared to 7.1% of the control group (p=0.002). At 120-minutes following treatment, responder rates were 46.8% in the Treatment group and 22.2% in the Control group (p=0.001). Improvement in Brief Pain Inventory interference score of 2.3 ± 0.29 was significantly greater in treatment group than the 1.3 ± 0.26-point change in the Control group (p = 0.01). Opioid usage, although not significantly different, trended towards a greater reduction in the treatment group than in the control group. The incidence of adverse events did not differ significantly between the treatment and control groups.Conclusion: The primary outcomes of the study were met, and the majority of Treatment patients experienced a substantial improvement in PAP (regardless of meeting the study definition of a responder). The significant in PAP was associated with significantly improved QOL metrics, and a trend towards reduced opioid utilization compared to Control. These data indicate that Altius treatment represents a significant therapeutic advancement for lower-limb amputees suffering from chronic PAP.Keywords: post-amputation pain, phantom limb pain, neuromodulation, peripheral nerve stimulation, high-frequency nerve bloc