New Paradigms in Spinal Cord Stimulation. Steven Falowski MD

Transcription

1 New Paradigms in Spinal Cord Stimulation Steven Falowski MD

2 Objectives Background of SCS Mechanisms of Action Indications Equipment Placement

3 Introduction Spinal cord stimulation (SCS) delivers electrical current to the spinal cord Ideal for Neuropathic Pain Adjustable Non- Destructive Neuromodulatory

4 Indications Most Common Post-laminectomy syndrome Complex regional pain syndrome (CRPS) Ischemic limb pain Angina Other visceral/abdominal pain cervical neuritis pain spinal cord injury pain post-herpetic neuralgia neurogenic thoracic outlet syndrome

5 Background Initially all unipolar electrodes Set Programming Only radio-frequency (RF) driven passive receivers were available.

6 Background 1970 s: Pulse Generator 1980 s: Percutaneous electrode Waltz et al 1982: First percutaneous quadripolar electrode 2004: Rechargeable Battery

7 Mechanism of Action Holsheimer,, Coburn, and Strujik: Distribution of the electrical fields within the spinal structures Holsheimer et al: : Effect of anode- cathode configuration on paresthesia coverage in spinal cord stimulation

8 Mechanism Of Action Barolat 1993: : Mapping of sensory responses Barolat 1998: : Anatomical and electrical properties of the intraspinal structures and clinical correlations

9 Mechanism of Action Foreman et al Primate Studies Linderoth et al Rat Studies At the chemical level, animal studies suggest that the SCS triggers the release of serotonin, substance P, and GABA within the dorsal horn?descending Inhibition

10 Mechanism of Action-Electrodes

11 Indications Post Laminectomy Syndrome CRPS Angina Abdominal/Visceral Pain 50% pain relief in 50-60% of the patients Maintained over several years

12 Post- Laminectomy Syndrome Etiology: Pain in Center Lower Lumbar Area Pain in Buttocks Radicular Pain Also included: Arachnoiditis Epidural Fibrosis Radiculitis Microinstability Recurrents Disc Herniations Infections

13 Stimulation of the Low Back Single vs Dual Electrode Law et al: Multiple Bipole Arrays North et al: Midline Quadripolar Electrode Tripole Electrode Steer Current Sharan 2007: : Lateral anodes increase discomfort threshold

14 Post- Laminectomy Syndrome Marchand et al: Pain scores reduced with SCS Prospective RCT Acted as Own Control Small Study Group

15 Post- Laminectomy Syndrome North et al-1991: SCS is superior to repeat surgery 50 patients Average 3 surgeries for FBSS prior to SCS 53% of patients had pain relief at 2.2 years Patient Satisfaction North et al-1995: Better outcomes with SCS Prospective RCT Repeat back surgery vs SCS Allowed Crossover

16 Post- Laminectomy Syndrome Turner-1995: Systematic Review of Literature 41 articles from % of patients had greater than 50% pain relief Burchiel et al-1996: 55% Successful Stimulation Prospective Multi- Center one year trial

17 Post- Laminectomy Syndrome Cameron 2004-JNS: 51 studies Total of 3,700 patients SCS had a positive, symptomatic, long-term effect in cases of: refractory angina pain, severe ischemic limb pain secondary to peripheral vascular disease, peripheral neuropathic pain, and chronic low-back pain

18 Complex Regional Pain Syndrome Pain and swelling in a single body part Pain may start after an injury Pain will usually gradually worsen Usually affects the hands, feet, elbows or knees Two Types: Type I: May not have cause Type II: Always follows an injury

19 Complex Regional Pain Syndrome

20 Complex Regional Pain Syndrome Challenges: Pain is not well defined Difficult to cover affected area with stimulation May aggravate original pain

21 CRPS-Early Work Barolat et at-1989 Pain reduction in 10 of 13 patients Short follow up Kumar et al month follow up of 12 patients All patients with pain relief

22 CRPS-More Recent Data Kemlar -1999: 78% pain relief 23 patients Kemlar- 2000: SCS vs Physical Therapy 54 Patients randomized 67% pain relief at 6 months Improved VAS scores Kemlar- 2006: Diminished effectiveness over 5 year follow up

23 CRPS-Limitations Difficult to cover affected area with stimulation Long- term efficacy is yet to be determined Improvement in pain scores, but not necessarily improvement in functional impairment

24 Angina Factors Involved EKG changes Time to Angina Exercise Capacity Recovery Time Use of Nitrates Anginal Attacks End Results Ischemia Myocardial Flow MI Arrhythmias

25 Angina-Use of SCS Lower cervical and upper thoracic region Continuous vs cyclical use Often use a low intensity stimulation for several hours per day for prophylactic purposes Eddicks S et al(2007): Continuous sub threshold stimulation RCT demonstrating improved functional status and symptoms Blinded

26 Angina-Efficacy of SCS DeJongste et al 1994: decrease in anginal attacks and nitrate consumption Treatment group as Control DiPede 2003: Immediate and long- term clinical outcome with SCS Prospective 104 pts with SCS for refractory angina Decrease anginal episodes at rest and with activity

27 Angina-Efficacy of SCS Vulink et al -1998: Improved pain and quality of life Hauvast et al-1998: Increased exercise duration and time to Angina Decreased Anginal Attacks Decreased use of Nitrates Decreased Ischemic episodes on EKG

28 Angina-ESBY Study Mannheimer et al : RCT: CABG vs SCS Prospective Non- Blinded Trial SCS/CABG: Both with 30% Improvement NHP scores 5 year Mortality: 27% in both groups No difference in the percentage of cardiac deaths

29 Angina-ESBY Study Mannheimer et al : Cardiac Events were similar across the groups *More Cerebrovascular events observed in CABG group* Eight in CABG group/two in SCS group Both groups had decrease in anginal attacks and decreased nitrate use No significant inter-group difference

30 Angina- ESBY Study Study Limitations: Limited number of patients Limited follow-up time Not Blinded

31 Conclusion of ESBY Study CABG and SCS appear to be equivalent methods in terms of symptom relief SCS may be a therapeutic alternative for patients with an increased risk of surgical complications

32 Angina-Mechanism of SCS Homogenization of myocardial blood perfusion with SCS Augustinsson et al : : SCS patients have improved heart muscle lactate metabolism, oxygen demand, and blood flow in the coronary sinus Hautvast et al: : No change in HR variability after 6 weeks i.e. autonomic modulation may not be the explanatory mechanism of action

33 Angina-Mechanism of SCS Foreman/Linderoth Linderoth: Pain Relief from direct inhibition of signal or decrease in ischemia? Decreased activity in Spinothalamic/Sympathetic Tracts in Rat Model Hautvast et al-1996: Positron emission tomography study Redistribution of myocardial flow in favor of ischemic parts of the myocardium Both at rest and after pharmacologic stress induction Demonstrated as a long- term effect of SCS

34 Angina The role of SCS in the management of refractory angina pectoris seems to be very promising Uniformly good results in the relief of Anginal pain shown in the literature Results maintained in long- term follow up Effects go beyond pain relief

35 Abdominal/Visceral Pain 20% of the population in United States has abdominal pain Many etiologies gastrointestinal genitourinary musculoskeletal nervous system Treatment modalities Cognitive- behavioral Physical Pharmacological therapies More Invasive: Celiac plexus blocks Celiac ganglia destruction

36 Abdominal/Visceral Pain-Initial Interest Some studies have demonstrated some localization in the spinal cord for visceral pain secondary to malignancy Hirschberg : : Increased Dorsal Column Activity Midline Myelotomy

37 Abdominal/Visceral Pain-Initial Case Reports: Ceballos et al-2000: Interest 2000: Mesenteric Ischemia Reduction in pain scores Decrease Narcotic Use Krames et al-2004: Irritable Bowel Syndrome Reduction in diarrhea Initial reduction in pain

38 Abdominal/Visceral Pain Khan et al-2005: Refractory Abdominal Pain Non- alcoholic pancreatitis,, abdominal wall neuromas,, post splenectomy pain All patients(9) had a significant improvement in VAS scores Decreased narcotic use Placement of the leads at the T5-7 7 level 8 month follow up

39 Abdominal/Visceral Pain Tiede et al: Multiple abdominal surgeries 2 patients Placed at T2 Relieved postprandial pain Decrease Narcotic Use Patients returned to work Kapural et al: Chronic visceral pelvic pain 6 females Endometriosis/Multiple Surgical Explorations >50% Pain relief Decrease opiate use Decrease VAS score 30 month follow up

40 Abdominal/Visceral Pain- Viscerotomes Mechanism Sympathetic and Parasympathetic Pathways The sympathetic afferents in the lower thoracic/upper lumbar spinal segments have been shown to transmit painful impulses from the viscera

41 Equipment

42 Equipment Rapidly Changing Multiple Stimulation Parameters Multiple Types of Electrodes and Combinations Increased Uses

43 Pulse Generators Two basic types Internal Pulse Generator Radiofrequency coupled pulse generator Rechargeable Pulse Generator Power Requirement Issues

44 Pulse Generators IPG: Lithium Battery Activation/Control occur through an external transcutaneous telemetry device Control by patient and physician Battery life: 2.5 to 4.5 years Outpatient surgery to replace

45 Pulse Generators Rechargeable Systems

46 SCS Model Large fibers activated near the cathode

47 Transverse tripolar stimulation (4 pts) Central cathode and two lateral anodes Anodes increase the discomfort threshold over the roots compared to the paresthesia threshold (thus increasing the therapeutic range) Lateral/medial steering advantage by setting different voltages of the flanking anodes Closer spacing = More effective fiber activation

48 Electrode Configurations - + UB GC LTS-2A LTS-4A LTS-6A 2 anodes 4 anodes 6 anodes

49 Tripole Paddle-Summary Similar activation ratios were obtained as with trialed percutaneous leads Lower paresthesia thresholds and energy per pulse were seen with the paddle than with the percutaneous array. Trialing with one or more percutaneous arrays can aid in determining the effectiveness of paddle arrays.

50 Awake versus non-awake Surgery for Placement of Spinal Cord Stimulators

51 Study Design A retrospective review of 291 internalization operations to determine whether first time awake surgery for placement of spinal cord stimulators is preferable to non-awake placement Electrode implantation can be performed either under monitored (local anesthetic and intravenous sedation) or under general anesthesia

52 Surgeries Performed BATTERY EOL FAILURE INFECTION NEW STIMULATOR REPOSITION 61% New Implantation 16% Failure 10% Repositioning of the battery or stimulator 7% EOL of the battery 6% are due to infection

53 Placement of Stimulator # cases Year Y # No Wakeup # Wakeup

54 Monitoring

55 Failure Rate #cases No Failure Failure Non Awake Surgical Failure Rate 16% Awake Surgical Failure Rate 31% * 10 0 Wakeup No Wakeup * = p<.05

56 Repositioning #cases No Reposition Reposition Non Awake Surgical Repositioning Rate 16% Awake Surgical Repositioning Rate 17% 10 0 Wakeup No Wakeup

57 Infection Non Awake Surgical Infection Rate 7% Awake Surgical Infection Rate 7% #cases No Infection Infection Wakeup No Wakeup

58 Summary Important Points: Radiographical position and motor stimulation responses to assure proper electrode positioning under general anesthesia Performed after a percutaneous trial Conclusion: Non-awake surgery is associated with fewer failure rates and therefore fewer re- operations, making it a viable alternative

59 SCS-Conclusions Conclusions SCS Technology is improving Equipment and stimulation parameters Reliable and safe modality Goal of neurostimulation is to reduce pain rather than to eliminate pain 50% improvement in pain relief Reduce use of pain medications Increasing amount of uses Importance of selection criteria

60 Thank You

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