The Franco-Canadian multicolumn spinal cord stimulation prospective study: a subgroup analysis focusing on the decisive role of lead positioning.

INTRODUCTION: Multicolumn spinal cord stimulation (SCS) is now considered to be effective for the treatment of the radicular and back component in refractory Failed Back Surgery Syndrome (FBSS) patients. The relationship between the paresthesia coverage of the back and clinical outcomes has recently been confirmed by an international prospective study. However, significant disparities in outcomes were identified and could result from the heterogeneity of lead implantation parameters which are dependant on local practices and experience. We therefore sought to analyse the impact of lead implantation level and its lateralization on the ability to address back pain with multicolumn SCS leads. STUDY OBJECTIVES, MATERIALS AND METHODS: The present study was a retrospective subgroup analysis from an observational, prospective non-randomized trial that included 76 patients with refractory FBSS, implanted with multicolumn SCS between 2008 to 2011 in three neurosurgical pain centres (Poitiers, France, Montreal, Canada and Regina, Canada). A subgroup of 21 patients with "optimized lead positioning" (OLP) was identified, distinguished from the rest of the main study population (NON OLP subgroup; n=51) and submitted to specific data analysis. Baseline characteristics of both groups were strictly comparable. Our primary objective was to analyse the impact of lead positioning (vertebral level and lateralization) on the back paresthesia coverage. The secondary objectives were to compare the analgesic and functional efficacy of multicolumn stimulation in these OLP and NON OLP subgroups and to determine if a paresthesia coverage improvement leads to better clinical outcomes in these difficult-to-treat patients. RESULTS: In this subgroup analysis, unilateral coverage of the low back area was achieved in 85.0% of OLP patients vs. 76.5% in the NON OLP group. Bilateral and complete coverage of the low back area was achieved in 60% of OLP patients vs. 51% in the NON OLP group but these differences were not statistically significant. At 6months, 81.0% of OLP patients vs. 69.4% in the NON OLP group presented at least 30% improvement of the low back VAS, while 52.4% of them achieved at least 50% improvement of the low back VAS vs. 38.8% in the NON OLP group. Functional improvement at 6months, available and calculated only in the French group of OLP patients (n=14) by the Oswestry Disability Index, was significant, decreasing from 60.67% to 33.43%. CONCLUSION: Despite limitations in this retrospective subgroup analysis, this study suggests that the vertebral level (T8-T9) and midline positioning of the lead during implantation could be decisive factors to optimize paresthesia coverage and finally, clinical and functional outcomes. While sophistication has been responsible for an increase of the size and the programming possibilities of surgical SCS leads during the past years, multicolumn SCS lead implantation should in fact be considered as a "functional neurosurgical" procedure and could benefit from intraoperative patient cooperation, as in the case for deep brain stimulation procedures, due to minimally invasive implantation techniques.

A prospective study evaluating sleep quality in Failed Back Surgery Syndrome patients treated by multicolumn spinal cord stimulation: study design protocol and presentation of the study population.

BACKGROUND AND PURPOSE: One of the main consequences of chronic pain syndrome is major impairment of the quality of sleep. Chronic pain and insomnia are independently linked to significant reductions in quality of life and psychiatric morbidity. Recent studies have suggested the efficacy of spinal cord stimulation (SCS) for the treatment of the back pain component in failed back surgery syndrome (FBSS) patients using a multicolumn lead. The main aim of this pilot study is to assess the influence and potential benefits of SCS on sleep quality in refractory FBSS patients implanted with multicolumn SCS and enrolled in the French multicentre ESTIMET study. METHODS: This is a single-centre, comparative, exploratory, pilot study. Sixteen FBSS patients enrolled in the ESTIMET study and implanted with multicolumn SCS will be monitored for 6months after implantation. Sleep parameters will be recorded by polysomnography, Psychomotor Vigilance Test and Osler tests, actigraphy, sleepiness scales, and sleep quality testing. Sleep will be evaluated before (at the inclusion visit) and after SCS implantation (at the 6-month visit). Secondary objectives will also assess the impact of SCS lead programming (mono vs. multicolumn SCS) and the influence of position-adaptive stimulation at night on sleep quality. TRIAL STATUS: The first patient of this ancillary study was enrolled on 21 May, 2012 and recruitment has now been achieved. Primary endpoint findings are expected to be available in 2015. CONCLUSION: By providing an analysis of the quality of sleep in chronic pain patients who are candidates for implanted neurostimulation, this new approach focuses on an important aspect of quality of life often overlooked in these poly-medication patients. It could show a real clinical benefit and underestimation of these analgesic innovative expensive techniques, where medico-economic analysis, would or would not promote access.

"MAST" prospective study: value of minimal access spine technologies technique for multicolumn spinal cord stimulation surgical lead implantation in the context of a French multicentre randomized controlled trial (ESTIMET study).

BACKGROUND AND PURPOSE: Spinal cord stimulation (SCS) has been demonstrated to be an effective treatment for postoperative persistent leg pain after spine surgery, but treatment of the back pain component remains much more difficult, as it comprises mixed neuropathic and mechanical pain mechanisms. Moreover, these patients could present damaged tissues at the site of SCS lead implantation as a result of previous spine surgery. It can therefore be logically assumed that minimizing the surgical invasiveness of SCS implantation would be beneficial for these patients. Several studies have demonstrated the value of Minimal Access Spine Technologies (MAST) in spine surgery, but only a few case reports have been published concerning the use of MAST techniques for SCS. Therefore, we were prompted to conduct a second ESTIMET ancillary study to prospectively analyse the potential impact and benefits of MAST technique during SCS lead implantation versus an open surgical approach. METHODS: This is a multicentre, comparative, ancillary study conducted in 61 patients among the 115 enrolled patients ESTIMET study. One arm comprises patients undergoing multicolumn lead implantation via a Conventional Open Approach (COA) and the other arm comprises patients implanted by a MAST approach. Patients will be followed for 12 months after lead implantation. The following data will be collected: elevation of muscle enzymes (serum CPK), scar size, blood loss, infection rate, operating time and global, leg, back and scar NPRS. TRIAL STATUS: The first patient of this ancillary study was enrolled on 21 May 2012 and recruitment has now been achieved. Primary endpoint findings are expected to be available in 2015. CONCLUSION: Minimally invasive techniques have now been used for spine surgery for the past 12 years, and could also be useful in the context of SCS lead implantation, especially in patients with chronic back pain prior to implantation.

A novel, objective, quantitative method of evaluation of the back pain component using comparative computerized multi-parametric tactile mapping before/after spinal cord stimulation and database analysis: the "Neuro-Pain't" software.

INTRODUCTION: One of the major challenges of neurostimulation is actually to address the back pain component in patients suffering from refractory chronic back and leg pain. Facing a tremendous expansion of neurostimulation techniques and available devices, implanters and patients can still remain confused as they need to select the right tool for the right indication. To be able to evaluate and compare objectively patient outcomes, depending on therapeutical strategies, it appears essential to develop a rational and quantitative approach to pain assessment for those who undergo neurostimulation implantation. OBJECTIVES, MATERIAL AND METHODS: We developed a touch screen interface, in Poitiers University Hospital and N(3)Lab, called the "Neuro-Pain'T", to detect, record and quantify the painful area surface and intensity changes in an implanted patient within time. The second aim of this software is to analyse the link between a paraesthesia coverage generated by a type of neurostimulation and a potential analgesic effect, measured by pain surface reduction, pain intensity reduction within the painful surface and local change in pain characteristics distribution. The third aim of Neuro-Pain'T is to correlate these clinical parameters to global patient data and functional outcome analysis, via a network database (Neuro-Database), to be able to provide a concise but objective approach of the neurostimulation efficacy, summarized by an index called "RFG Index". RESULTS AND DISCUSSION: This software has been used in more than 190 patients since 2012, leading us to define three clinical parameters grouped as a clinical component of the RFG Index, which might be helpful to assess neurostimulation efficacy and compare implanted devices. CONCLUSION: The Neuro-Pain'T is an original software designed to objectively and quantitatively characterize reduction of a painful area in a given individual, in terms of intensity, surface and pain typology, in response to a treatment strategy or implantation of an analgesic device. Because pain is a physical sensation, which integrates a psychological dimension, its assessment justifies the use of multidimensional and global evaluation scales. However, in the context of neurostimulation and comparative clinical trials designed to test the technical efficacy of a given device, a simple, objective and quantitative evaluation tool could help to guide tomorrow's treatment options by transforming personal convictions into a more robust scientific rationale based on data collection and data mining techniques.

The "neuro-mapping locator" software. A real-time intraoperative objective paraesthesia mapping tool to evaluate paraesthesia coverage of the painful zone in patients undergoing spinal cord stimulation lead implantation.

INTRODUCTION: Conventional spinal cord stimulation (SCS) generates paraesthesia, as the efficacy of this technique is based on the relationship between the paraesthesia provided by SCS on the painful zone and an analgesic effect on the stimulated zone. Although this basic postulate is based on clinical evidence, it is clear that this relationship has never been formally demonstrated by scientific studies. There is a need for objective evaluation tools ("transducers") to transpose electrical signals to clinical effects and to guide therapeutic choices. MATERIAL AND METHODS: We have developed a software at Poitiers University hospital allowing real-time objective mapping of the paraesthesia generated by SCS lead placement and programming during the implantation procedure itself, on a touch screen interface. OBJECTIVES: The purpose of this article is to describe this intraoperative mapping software, in terms of its concept and technical aspects. RESULTS AND DISCUSSION: The Neuro-Mapping Locator (NML) software is dedicated to patients with failed back surgery syndrome, candidates for SCS lead implantation, to actively participate in the implantation procedure. Real-time geographical localization of the paraesthesia generated by percutaneous or multicolumn surgical SCS lead implanted under awake anaesthesia allows intraoperative lead programming and possibly lead positioning to be modified with the patient's cooperation. Software updates should enable us to refine objectives related to the use of this tool and minimize observational biases. The ultimate goals of NML software should not be limited to optimize one specific device implantation in a patient but also allow to compare instantaneously various stimulation strategies, by characterizing new technical parameters as "coverage efficacy" and "device specificity" on selected subgroups of patients. Another longer-term objective would be to organize these predictive factors into computer science ontologies, which could constitute robust and helpful data for device selection and programming of tomorrow's neurostimulators.