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605 SPANISH GUIDELINES FOR NEUROSTIMULATION
S158
European Journal of Pain 2006, Vol 10 (suppl S1)
601 TARGETED SUBCUTANEOUS PERMAMENT NEUROMODULATION IMPLANT IN TREATMENT OF INTRACTABLE ANGINA T. Goroszeniuk, S. Kothari ° . Pain Management Centre, Guy’s and St. Thomas’ NHS Foundation Trust, London, UK Introduction: Angina not amendable to surgery or not responsive to pharmacological interventions is one of the prime indications for treatment with SCS. Following successful application of slow frequency needle & monoelectrode stimulation for angina1, we report successful percutaneous permanent subcutaneous electrode implantation in management of intractable angina. Two patients had a failed to respond to SCS. Methods: Six patients not responding to medication and not suitable for surgery or cardiological intervention were assessed according to peripheral neuromodulation tests 2 developed in our centre. 4 patients were implanted with permanent neuromodulation devices providing them with an excellent pain relief; 2 awaiting permanent implantation. Technique involved directing a stimulating needle to most painful area using slow frequency and subsequently passing an electrode percutaneously through it for implantation. Discussion: The mechanisms of action of SCS in treatment of angina suggests beneficial effects of dilatation of coronary vessels secondary to electrical stimulation of the spinal cord. As to why subcutaneous targeted stimulation at the painful area relieving angina has been so successful will warrant further detailed investigations, especially taking into account good pain relief provided, simplicity and effectiveness of the Targeted technique.
Abstracts, 5th EFIC Congress, Free Presentations 603 PERIPHERAL NERVE FIELD STIMULATION A. Koulousakis1 ° , A. Ntouvali1 , A. Krasoudakis1 , G. Koutsoumbelis2 . 1 Dept. of Sterotaxy/Uni-Kliniken, Cologne, Germany, 2 GNA-Hospital Athens, Greece Introduction: The effect of subcutaneous placed electrodes was tested through a pilotstudy. Methods and Results: 31 patients, with mainly nociceptive pain or allodynia, received a subcutan implantation of 2−4 electrodes, in order to asses the whole pain area. After a trial period of up to a week, the permanent electrodes where subcutaneous implanted and connected to a generator (Genesis/Eon). 30% of the patients displayed a pain reduction of more than 50%. The method is simple and can also serve as a predictor for spinal stimulation. The results are better for allodynia such as CRPS I. Conclusion: Subcutan field stimulation can be successfully performed easily and without risks for the treatment of chronic, non radicular, pain.
604 INCREASED MYOCARDIAL BLOOD FLOW AFTER SPINAL CORD STIMULATION IN PATIENTS WITH REFRACTORY ANGINA PECTORIS A. Koulousakis1 ° , H. Dietrichs2 , E. Voth3 , M. Weber1 , C. Zobel2 , R. Schwinger2 . 1 Dept. of Sterotaxy/Uni-Kliniken, Cologne, 2 Department of Cardiology/Uni-Kliniken, Cologne, 3 Department of Nuclear medicine/Uni-Kliniken, Cologne, Germany
References [1] Kothari S, Goroszeniuk T, Al-Kaisy A. Peripheral percutaneous stimulation for refractory angina pectoris. Regional Anesthesia and Pain Medicine 2004. P: 99, N 5, Vol: 29, Supp: 2. [2] Goroszeniuk T, Kothari S, Hamman W. The treatment of nonsegmental intractable pain syndrome by percutaneous implantation of a subcutaneous neurostimulation electrode. Regional Anesthesia and Pain Medicine 2006; 31: 2, P168–172.
602 EXTERNAL NEUROMODULATION (EN) AS A DIAGNOSTIC TEST AND THERAPEUTIC PROCEDURE S. Kothari ° , T. Goroszeniuk. Pain Management Centre, St. Thomas’ Hospital, London, UK Introduction: External Neuromodulation 1 (EN) involves application of electrical stimulation via an external nerve mapping probe connected to an impulse generator, to the nerves covering distribution of the painful area or directly to the epicenter of the painful area (TARGET). Methods: Diagnostic testing with EN is developed in our centre as a test prior to permanent electrode implantation. The stimulation is performed at a frequency of 2 Hz and amplitude adjusted to patient reporting acceptable paraesthesia in the painful area for 5 minutes. 50% and above improvement in pain qualifies as a positive test. Therapeutic benefit can be seen when the duration of pain relief lasts for more than few hours, in which case it can be repeated at regular intervals. The effects of external stimulation do not correlate with TENS applied externally over the same area. The External application allows the procedure to be performed on an outpatient basis. We report 240 patients tested with EN. 86% of cases benefited with excellent reproducible pain relief. Following the successful tests a proportion of patients who benefited from medium term relief have been undergoing repeat procedures or considered for self administration. Conclusions: External Neuromodulation a noninvasive modality is not only an effective initial indicator prior to permanent percutaneous peripheral neuromodulation implantation but also plays a role as a sole therapeutic intervention in management of chronic intractable pain. References [1] Goroszeniuk T., Kothari S. Targeted External Area Stimulation. Regional Anesthesia and Pain Medicine. Aug 2004. Supp 4; Vol. 29; No.5: Page 98.
Introduction: Inspite of great progresses in surgical and catheter interventional techniques there is an increasing number of patients with coronary heart disease not suitable for these conventional treatment strategies. A number of patients suffer from intractable pain in spite of appropriate medication. Methods and Results: 30 patients were randomized for SCS after a strong selection protocol, according to the ESBY-Study. The protocol includes the Seattle Angina Questionnaire, stress tolerance, heart szintigraphy and heart catheter examinations. Follow ups were conducted after 3, as well as 12 months (symptoms, walktest, ergometry, and szintigraphy, drug medication and quality of life). The quadropolar electrode was placed at the level TH1-left paramedian and after a trial period it was connected to a programmable pulse generator. By reduction of angina symptoms and a consecutive increase of exercise capacity, the patients experience a great improvement in quality of life. In addition, recent data of our own study suggest a significant decrease in myocardial ischemia – examined by MIBI-SPECT – in 23 patients under SCS. After 1 year of SCS, a significant improvement of the myocardial blood flow was registered in 16 patients, while being equal in 10. This might be a direct effect of SCS perhaps due to sympaticolysis or due to a better collateralization because of the improved exercise capacity. Conclusion: In agreement with the study group of the ESC, we would recommend SCS as first-line therapy for refractory angina pectoris. As a matter of course, conventional treatment strategies should not be replaced by SCS.
605 SPANISH GUIDELINES FOR NEUROSTIMULATION G. Cerd´a-Olmedo1 , M.L. Franco-Gay2 , J. Insausti3 , M.D. L´opez-Alarc´on1 , J.M. L´opez-Mill´an4 ° , S. Moliner-Vel´azquez1 , V. Monsalve-Dolz1 , L.A. Moreno5 , J. P´erez-Cajaraville6 , M. Ti´o-Felip5 , E. Uriarte3 . 1 Consorcio Hospital General Universitario, Valencia, 2 Hospital de Cruces, Barakaldo, Vizcaya, 3 Hospital Severo Ochoa, Legan´es, Madrid, 4 Hospital Universitario Virgen Macarena, Sevilla, 5 Hospital Cl´ınico, Barcelona, 6 Cl´ınica Universitaria de Navarra, Pamplona, Spain Introduction: The SGNM was created and the supported by ESRASpain to promote the knowledge and to standard the indications of the neurostimulation procedures in our country. A group of experts with an
Topic D: TREATMENT APPROACHES (MEDICAL/INTERVENTIONAL) extensive personal experience in the use of neuromodulation procedures has been working to settle the “how to do it” in this not well known therapy in our country. Objectives: As a consensus statement, this guideline has established several goals: 1. To gather all the knowledge available about neurostimulation 2. Teaching tool 3. To help care providers in their decision making process 4. To standardized clinical practice in order to obtain better results and comparable data for analysis Method: By discussing literature available and based on the group members personal experiences, and using the EBM criteria. Results: The SGNM has created the Spanish Guidelines for Neurostimulation containing 8 chapters and 2 appendix as follows: Chapter 1: Introduction. Objectives. Chapter 2: Desirable characteristics for clinicians and facilities. Chapter 3: Psychological testing. Chapter 4: Informed consent and general information. Chapter 5: Preparation for the implant. Chapter 6: Implant technique. Chapter 7: Follow up visit. Chapter 8: Complications. Appendix I: Programming for Spinal Cord Stimulation. Appendix II: Cost-Effectiveness analysis. Conclusion: There is no other document in our country that summarizes the theoretical and practical knowledge about electrical stimulation to treat chronic pain. We believe this project will be an approach for clinicians to this field, and a challenge for the SNMG to review this and many other topics related to neurmodulation therapies.
606 CONCEPT: CROSSOVER EFFICACY PAIN TRIAL IN MOTOR CORTEX STIMULATION “ON-GOING CLINICAL TRIAL” J-P. Nguyen1 ° , B. Nuttin2 , W. Eisner3 , C. Raftopoulos4 , B. Pirotte5 , J-M. Remacle6 , J-P. Van Buyten7 , H. Colle8 , V. Tronnier9 , D. Hellwig10 . 1 Department of Neurosurgery, Hˆ opital Henri Mondor, Cr´eteil, France, 2 Department of Neurosurgery, UZ Gasthuisberg, Leuven, Belgium, 3 Department of Neurosurgery, Universit¨ atsklinik Innsbruck, Innsbruck, Austria, 4 Department of Neurosurgery, UCL St Luc, Brussels, 5 Department of Neurosurgery, Hˆ opital Erasme, Brussels, 6 Department of Neurosurgery, CH de la Citadelle, Li`ege, 7 Pain Clinic, Maria Middelares ZH, St. Niklaas, 8 Department of Neurosurgery, AZ St Lucas, Gent, Belgium, 9 Department of Neurosurgery, Universit¨atsklinikum Schleswig-Holstein, L¨ubeck, 10 Department of Neurosurgery, Klinikum der Philipps-Universit¨at Marburg, Marburg, Germany Background and Aims: A prospective, randomized, double-blind, crossover (1:1) study to assess efficacy of Motor Cortex Stimulation (MCS) and overall safety of MCS by evaluation of all reported adverse events. A new cortical lead has been developed (8 contact electrode, circular paddle lead, Medtronic Inc, Minneapolis, USA), allowing for a more precise stimulation of the cortical target zone.
Figure 1. Study design overview
S159 Methods: 104 patients with persistent central post-stroke pain or trigeminal neuropathic pain will be randomized according to Figure 1. Target localization is the central fissure as visualized by CT scan and MRI, and confirmed by SomatoSensory Evoked Potentials and Motor Evoked Potentials. Results: To date 10 patients have been treated in the framework of this study. It is planned that patient enrollment will be completed by 2008. Conclusions: Twelve-month follow up will be completed in 2009. 607 SPINAL CORD STIMULATION WITH INTERLEAVED PULSES: A RANDOMIZED, CONTROLLED TRIAL R.B. North1 ° , D.H. Kidd1 , J. Olin1 , J.M. Sieracki1 , M. Boulay2 . 1 Dept. of Neurosurgery, Johns Hopkins University/Hospital, Baltimore, MD, 2 Dept. of Population and Family Health Sciences, Johns Hopkins University/School of Public Health, Baltimore, MD, USA Background and Aims: The development of multi-contact electrodes supported by programmable, implanted pulse generators has increased the therapeutic success of spinal cord stimulation (SCS) by improving our ability to capture and maintain pain/paresthesia overlap. We compared the effect on pain/paresthesia overlap of stimulating with rapidly interleaved pulses using different contact combinations versus standard treatment using a single contact combination, controlling for effects of frequency doubling. Methods: Using a patient-interactive computer system that quantifies SCS stimulator performance in randomized, double-blind fashion, we compared the effects of interleaving two different contact combinations with using each contact combination alone or interleaved with itself (frequency doubling). Pulse voltage or width were adjusted to subjectively identical intensities. The number of percutaneous spinal electrodes used (one or two), and the phase angle between interleaved pulses, were additional study variables. Results: Multivariate analysis of 266 test results from 15 patients revealed a statistically significant (p < 0.05) association between achieving clinically useful computer-calculated pain/paresthesia overlap and 1) interleaved stimulation at high and low frequency using two contact combinations and 2) frequency doubling using one combination. We found no significant effect for electrode configuration (single or dual), pulse width matching, or phase angle. Conclusion: The statistically significant advantages we observed for SCS with interleaved stimulation and with frequency doubling have important implications for the design and adjustment of pulse generators. 608 NECESSITY OF SURGICAL APPROACH IN SPINAL CORD STIMULATION M.J. Ordu˜na Gonz´alez1 ° , M.L. Janeiro1 , F.J. Pardo Sobrino1 , E. Aran Echave2 , J.M. Fandi˜no Rivera2 , M. L´opez Rouco1 . 1 Department of Anesthesia and General Intensive Care, Hospital Xeral, Lugo, 2 Department of Neurosurgery, Hospital Xeral Calde, Lugo, Spain Background: The use of implanted induced electrical stimulation was introduced in 1967 by Shely et al. The dorsal column stimulation has been applied to a wide variety of pain disorders. Two different spinal cord stimulations are routinely used: those involving percutaneously placed electrode leads and those requiring laminectomies to allow placement of the electrodes. The most frequently reported technical complications are electrode dislocation and breakage, as well as pulse generator or battery failures. Methods: We show tree cases of surgical approach to allow placement of electrodes epidural. Case report: A 43 year old female with radicular chronic pain by failed back surgery syndrome. We had implanted tree percutaneous electrodes all old had broken. The fourth electrode requiring laminectomy level T1−T2. Case report: A 46 year old male with failed back cervical surgery syndrome. Artrodhesis C4–C5. Radicular pain and brachialgia C5–C6– C7.
European Journal of Pain 2006, Vol 10 (suppl S1)
601 TARGETED SUBCUTANEOUS PERMAMENT NEUROMODULATION IMPLANT IN TREATMENT OF INTRACTABLE ANGINA T. Goroszeniuk, S. Kothari ° . Pain Management Centre, Guy’s and St. Thomas’ NHS Foundation Trust, London, UK Introduction: Angina not amendable to surgery or not responsive to pharmacological interventions is one of the prime indications for treatment with SCS. Following successful application of slow frequency needle & monoelectrode stimulation for angina1, we report successful percutaneous permanent subcutaneous electrode implantation in management of intractable angina. Two patients had a failed to respond to SCS. Methods: Six patients not responding to medication and not suitable for surgery or cardiological intervention were assessed according to peripheral neuromodulation tests 2 developed in our centre. 4 patients were implanted with permanent neuromodulation devices providing them with an excellent pain relief; 2 awaiting permanent implantation. Technique involved directing a stimulating needle to most painful area using slow frequency and subsequently passing an electrode percutaneously through it for implantation. Discussion: The mechanisms of action of SCS in treatment of angina suggests beneficial effects of dilatation of coronary vessels secondary to electrical stimulation of the spinal cord. As to why subcutaneous targeted stimulation at the painful area relieving angina has been so successful will warrant further detailed investigations, especially taking into account good pain relief provided, simplicity and effectiveness of the Targeted technique.
Abstracts, 5th EFIC Congress, Free Presentations 603 PERIPHERAL NERVE FIELD STIMULATION A. Koulousakis1 ° , A. Ntouvali1 , A. Krasoudakis1 , G. Koutsoumbelis2 . 1 Dept. of Sterotaxy/Uni-Kliniken, Cologne, Germany, 2 GNA-Hospital Athens, Greece Introduction: The effect of subcutaneous placed electrodes was tested through a pilotstudy. Methods and Results: 31 patients, with mainly nociceptive pain or allodynia, received a subcutan implantation of 2−4 electrodes, in order to asses the whole pain area. After a trial period of up to a week, the permanent electrodes where subcutaneous implanted and connected to a generator (Genesis/Eon). 30% of the patients displayed a pain reduction of more than 50%. The method is simple and can also serve as a predictor for spinal stimulation. The results are better for allodynia such as CRPS I. Conclusion: Subcutan field stimulation can be successfully performed easily and without risks for the treatment of chronic, non radicular, pain.
604 INCREASED MYOCARDIAL BLOOD FLOW AFTER SPINAL CORD STIMULATION IN PATIENTS WITH REFRACTORY ANGINA PECTORIS A. Koulousakis1 ° , H. Dietrichs2 , E. Voth3 , M. Weber1 , C. Zobel2 , R. Schwinger2 . 1 Dept. of Sterotaxy/Uni-Kliniken, Cologne, 2 Department of Cardiology/Uni-Kliniken, Cologne, 3 Department of Nuclear medicine/Uni-Kliniken, Cologne, Germany
References [1] Kothari S, Goroszeniuk T, Al-Kaisy A. Peripheral percutaneous stimulation for refractory angina pectoris. Regional Anesthesia and Pain Medicine 2004. P: 99, N 5, Vol: 29, Supp: 2. [2] Goroszeniuk T, Kothari S, Hamman W. The treatment of nonsegmental intractable pain syndrome by percutaneous implantation of a subcutaneous neurostimulation electrode. Regional Anesthesia and Pain Medicine 2006; 31: 2, P168–172.
602 EXTERNAL NEUROMODULATION (EN) AS A DIAGNOSTIC TEST AND THERAPEUTIC PROCEDURE S. Kothari ° , T. Goroszeniuk. Pain Management Centre, St. Thomas’ Hospital, London, UK Introduction: External Neuromodulation 1 (EN) involves application of electrical stimulation via an external nerve mapping probe connected to an impulse generator, to the nerves covering distribution of the painful area or directly to the epicenter of the painful area (TARGET). Methods: Diagnostic testing with EN is developed in our centre as a test prior to permanent electrode implantation. The stimulation is performed at a frequency of 2 Hz and amplitude adjusted to patient reporting acceptable paraesthesia in the painful area for 5 minutes. 50% and above improvement in pain qualifies as a positive test. Therapeutic benefit can be seen when the duration of pain relief lasts for more than few hours, in which case it can be repeated at regular intervals. The effects of external stimulation do not correlate with TENS applied externally over the same area. The External application allows the procedure to be performed on an outpatient basis. We report 240 patients tested with EN. 86% of cases benefited with excellent reproducible pain relief. Following the successful tests a proportion of patients who benefited from medium term relief have been undergoing repeat procedures or considered for self administration. Conclusions: External Neuromodulation a noninvasive modality is not only an effective initial indicator prior to permanent percutaneous peripheral neuromodulation implantation but also plays a role as a sole therapeutic intervention in management of chronic intractable pain. References [1] Goroszeniuk T., Kothari S. Targeted External Area Stimulation. Regional Anesthesia and Pain Medicine. Aug 2004. Supp 4; Vol. 29; No.5: Page 98.
Introduction: Inspite of great progresses in surgical and catheter interventional techniques there is an increasing number of patients with coronary heart disease not suitable for these conventional treatment strategies. A number of patients suffer from intractable pain in spite of appropriate medication. Methods and Results: 30 patients were randomized for SCS after a strong selection protocol, according to the ESBY-Study. The protocol includes the Seattle Angina Questionnaire, stress tolerance, heart szintigraphy and heart catheter examinations. Follow ups were conducted after 3, as well as 12 months (symptoms, walktest, ergometry, and szintigraphy, drug medication and quality of life). The quadropolar electrode was placed at the level TH1-left paramedian and after a trial period it was connected to a programmable pulse generator. By reduction of angina symptoms and a consecutive increase of exercise capacity, the patients experience a great improvement in quality of life. In addition, recent data of our own study suggest a significant decrease in myocardial ischemia – examined by MIBI-SPECT – in 23 patients under SCS. After 1 year of SCS, a significant improvement of the myocardial blood flow was registered in 16 patients, while being equal in 10. This might be a direct effect of SCS perhaps due to sympaticolysis or due to a better collateralization because of the improved exercise capacity. Conclusion: In agreement with the study group of the ESC, we would recommend SCS as first-line therapy for refractory angina pectoris. As a matter of course, conventional treatment strategies should not be replaced by SCS.
605 SPANISH GUIDELINES FOR NEUROSTIMULATION G. Cerd´a-Olmedo1 , M.L. Franco-Gay2 , J. Insausti3 , M.D. L´opez-Alarc´on1 , J.M. L´opez-Mill´an4 ° , S. Moliner-Vel´azquez1 , V. Monsalve-Dolz1 , L.A. Moreno5 , J. P´erez-Cajaraville6 , M. Ti´o-Felip5 , E. Uriarte3 . 1 Consorcio Hospital General Universitario, Valencia, 2 Hospital de Cruces, Barakaldo, Vizcaya, 3 Hospital Severo Ochoa, Legan´es, Madrid, 4 Hospital Universitario Virgen Macarena, Sevilla, 5 Hospital Cl´ınico, Barcelona, 6 Cl´ınica Universitaria de Navarra, Pamplona, Spain Introduction: The SGNM was created and the supported by ESRASpain to promote the knowledge and to standard the indications of the neurostimulation procedures in our country. A group of experts with an
Topic D: TREATMENT APPROACHES (MEDICAL/INTERVENTIONAL) extensive personal experience in the use of neuromodulation procedures has been working to settle the “how to do it” in this not well known therapy in our country. Objectives: As a consensus statement, this guideline has established several goals: 1. To gather all the knowledge available about neurostimulation 2. Teaching tool 3. To help care providers in their decision making process 4. To standardized clinical practice in order to obtain better results and comparable data for analysis Method: By discussing literature available and based on the group members personal experiences, and using the EBM criteria. Results: The SGNM has created the Spanish Guidelines for Neurostimulation containing 8 chapters and 2 appendix as follows: Chapter 1: Introduction. Objectives. Chapter 2: Desirable characteristics for clinicians and facilities. Chapter 3: Psychological testing. Chapter 4: Informed consent and general information. Chapter 5: Preparation for the implant. Chapter 6: Implant technique. Chapter 7: Follow up visit. Chapter 8: Complications. Appendix I: Programming for Spinal Cord Stimulation. Appendix II: Cost-Effectiveness analysis. Conclusion: There is no other document in our country that summarizes the theoretical and practical knowledge about electrical stimulation to treat chronic pain. We believe this project will be an approach for clinicians to this field, and a challenge for the SNMG to review this and many other topics related to neurmodulation therapies.
606 CONCEPT: CROSSOVER EFFICACY PAIN TRIAL IN MOTOR CORTEX STIMULATION “ON-GOING CLINICAL TRIAL” J-P. Nguyen1 ° , B. Nuttin2 , W. Eisner3 , C. Raftopoulos4 , B. Pirotte5 , J-M. Remacle6 , J-P. Van Buyten7 , H. Colle8 , V. Tronnier9 , D. Hellwig10 . 1 Department of Neurosurgery, Hˆ opital Henri Mondor, Cr´eteil, France, 2 Department of Neurosurgery, UZ Gasthuisberg, Leuven, Belgium, 3 Department of Neurosurgery, Universit¨ atsklinik Innsbruck, Innsbruck, Austria, 4 Department of Neurosurgery, UCL St Luc, Brussels, 5 Department of Neurosurgery, Hˆ opital Erasme, Brussels, 6 Department of Neurosurgery, CH de la Citadelle, Li`ege, 7 Pain Clinic, Maria Middelares ZH, St. Niklaas, 8 Department of Neurosurgery, AZ St Lucas, Gent, Belgium, 9 Department of Neurosurgery, Universit¨atsklinikum Schleswig-Holstein, L¨ubeck, 10 Department of Neurosurgery, Klinikum der Philipps-Universit¨at Marburg, Marburg, Germany Background and Aims: A prospective, randomized, double-blind, crossover (1:1) study to assess efficacy of Motor Cortex Stimulation (MCS) and overall safety of MCS by evaluation of all reported adverse events. A new cortical lead has been developed (8 contact electrode, circular paddle lead, Medtronic Inc, Minneapolis, USA), allowing for a more precise stimulation of the cortical target zone.
Figure 1. Study design overview
S159 Methods: 104 patients with persistent central post-stroke pain or trigeminal neuropathic pain will be randomized according to Figure 1. Target localization is the central fissure as visualized by CT scan and MRI, and confirmed by SomatoSensory Evoked Potentials and Motor Evoked Potentials. Results: To date 10 patients have been treated in the framework of this study. It is planned that patient enrollment will be completed by 2008. Conclusions: Twelve-month follow up will be completed in 2009. 607 SPINAL CORD STIMULATION WITH INTERLEAVED PULSES: A RANDOMIZED, CONTROLLED TRIAL R.B. North1 ° , D.H. Kidd1 , J. Olin1 , J.M. Sieracki1 , M. Boulay2 . 1 Dept. of Neurosurgery, Johns Hopkins University/Hospital, Baltimore, MD, 2 Dept. of Population and Family Health Sciences, Johns Hopkins University/School of Public Health, Baltimore, MD, USA Background and Aims: The development of multi-contact electrodes supported by programmable, implanted pulse generators has increased the therapeutic success of spinal cord stimulation (SCS) by improving our ability to capture and maintain pain/paresthesia overlap. We compared the effect on pain/paresthesia overlap of stimulating with rapidly interleaved pulses using different contact combinations versus standard treatment using a single contact combination, controlling for effects of frequency doubling. Methods: Using a patient-interactive computer system that quantifies SCS stimulator performance in randomized, double-blind fashion, we compared the effects of interleaving two different contact combinations with using each contact combination alone or interleaved with itself (frequency doubling). Pulse voltage or width were adjusted to subjectively identical intensities. The number of percutaneous spinal electrodes used (one or two), and the phase angle between interleaved pulses, were additional study variables. Results: Multivariate analysis of 266 test results from 15 patients revealed a statistically significant (p < 0.05) association between achieving clinically useful computer-calculated pain/paresthesia overlap and 1) interleaved stimulation at high and low frequency using two contact combinations and 2) frequency doubling using one combination. We found no significant effect for electrode configuration (single or dual), pulse width matching, or phase angle. Conclusion: The statistically significant advantages we observed for SCS with interleaved stimulation and with frequency doubling have important implications for the design and adjustment of pulse generators. 608 NECESSITY OF SURGICAL APPROACH IN SPINAL CORD STIMULATION M.J. Ordu˜na Gonz´alez1 ° , M.L. Janeiro1 , F.J. Pardo Sobrino1 , E. Aran Echave2 , J.M. Fandi˜no Rivera2 , M. L´opez Rouco1 . 1 Department of Anesthesia and General Intensive Care, Hospital Xeral, Lugo, 2 Department of Neurosurgery, Hospital Xeral Calde, Lugo, Spain Background: The use of implanted induced electrical stimulation was introduced in 1967 by Shely et al. The dorsal column stimulation has been applied to a wide variety of pain disorders. Two different spinal cord stimulations are routinely used: those involving percutaneously placed electrode leads and those requiring laminectomies to allow placement of the electrodes. The most frequently reported technical complications are electrode dislocation and breakage, as well as pulse generator or battery failures. Methods: We show tree cases of surgical approach to allow placement of electrodes epidural. Case report: A 43 year old female with radicular chronic pain by failed back surgery syndrome. We had implanted tree percutaneous electrodes all old had broken. The fourth electrode requiring laminectomy level T1−T2. Case report: A 46 year old male with failed back cervical surgery syndrome. Artrodhesis C4–C5. Radicular pain and brachialgia C5–C6– C7.