Transcript (EVIDENCE study).

Evidence Based Medicine for
SCS
Steven M. Falowski MD
St. Lukes Health Network
Bethlehem, PA
Advantages of SCS Therapy
Safe
Testable
Non-destructive
Mostly reversible
Long-term cost is low
Less Risky
Disadvantages of SCS Therapy
Limited to specific indications and diseases
Equipment failure
Follow-up lifelong?
Short-term cost is high
Inability to get MRI
Indications
Most Common
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–
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Post-laminectomy syndrome
Complex regional pain syndrome (CRPS)
Ischemic limb pain
Angina
Other
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visceral/abdominal pain
cervical neuritis pain
spinal cord injury pain
post-herpetic neuralgia
neurogenic thoracic outlet syndrome
Mechanism of Action
Foreman et al. 1976 Primate Studies
Linderoth et al. 1992 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
Mechanism Of Action
Barolat 1993: Mapping of sensory
responses
Barolat 1998: Anatomical and electrical
properties of the intraspinal structures and
clinical correlations
Mechanism of Action-Electrodes
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
Post- Laminectomy Syndrome
Etiology:
– Pain in Center Lower
Lumbar Area
– Pain in Buttocks
– Radicular Pain
Also included:
–
–
–
–
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Arachnoiditis
Epidural Fibrosis
Radiculitis
Microinstability
Recurrents Disc
Herniations
– Infections
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
– 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
Results
CLINICAL RESULTS: CLBP
North et al Neurosurgery 2005;56:98107
FBSS patients (%)
100
RCT
p = 0.0005
80
SCS
Reoperation
p = 0.0149
60
40
20
0
More than 50%
pain relief
Increase in
opiate analgesia
SCS in CLBP
Clinical efficacy:
– RCT:
47% SCS patients had 50% pain relief and expressed
satisfaction with treatment, compared with only 12%
reoperation patients
87% of SCS patients had stable or reduced opioid use;
42% reoperation patients required an increase
Cost effectiveness:
– Considerable cost savings after 2.5 years
Quality of life with
neurostimulation in CLBP
6%
34%
60%
Worsening
Improved
No change
78% of patients would recommend SCS to someone with
a similar problem,
75% of patients would have the procedure performed
again if they had known their outcome before implantation
1. Ohnmeiss DD, Rashbaum RF. The Spine Journal 2001;1:258-363 [dual leads were required for these patients]
Spinal cord stimulation versus re-operation in patients with failed back
surgery syndrome: an international multicenter randomized controlled
trial (EVIDENCE study).
North RB, Kumar K, Wallace MS, Henderson JM, Shipley J, Hernandez J, Mekel-Bobrov
N, Jaax KN.
Neuromodulation. 2011 Jul-Aug
Assess the effectiveness and cost-effectiveness of spinal
cord stimulation (SCS) with rechargeable pulse
generator versus re-operation
Study subjects have neuropathic radicular leg pain
exceeding or equaling any low back pain and meet
specified entry criteria.
Co-primary endpoints are proportion of subjects
reporting ≥ 50% leg pain relief without crossover after
SCS screening trial or re-operation.
Secondary endpoints include cost-effectiveness; relief of
leg, back, and overall pain; change in disability and
quality of life; and rate of crossover.
Complex Regional Pain
Syndrome
CRPS-Early Work
Barolat et at-1989
– Pain reduction in 10 of 13 patients
– Short follow up
Kumar et al- 1997
– 41 month follow up of 12 patients
– All patients with pain relief
CRPS
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
Long-term outcomes of spinal cord stimulation with paddle leads in the treatment
of complex regional pain syndrome and failed back surgery syndrome.
Sears NC, Machado AG, Nagel SJ, Deogaonkar M, Stanton-Hicks M, Rezai AR,
Henderson JM.
Neuromodulation. 2011 Jul-Aug
More than 50% of the patients with CRPS
reported greater than 50% pain relief at a mean
follow-up of 4.4 years.
Approximately 30% of the FBSS patients
reported a 50% or greater improvement at a
mean follow-up of 3.8 years.
However, 77.8% of patients with CRPS and
70.6% of patients with FBSS indicated that they
would undergo SCS surgery again for the same
outcome.
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
Awake vs. Asleep Placement of Spinal Cord
Stimulators: A Cohort Analysis of Complications
Associated With Placement
Steven M. Falowski, MD, Amanda Celii, MD, Anthony K. Sestokas, PhD,
Daniel M. Schwartz, PhD, Craig Matsumoto, MPAS, Ashwini Sharan, MD
Neuromodulation. 2011 Mar-Apr;14(2):130-4; discussion 134-5
A retrospective review of 167 new
internalization operations
Electrode implantation performed either
under monitored (local anesthetic and
intravenous sedation) or under general
anesthesia
Awake versus non-Awake Surgery for Placement of Spinal Cord
Stimulators
Device failure for patients implanted using
neurophysiologically-guided placement
under general anesthesia was one-half
that for patients implanted awake (14.94%
vs 29.7%).
No difference in repositioning or infection
rate
Awake versus non-Awake Surgery for Placement of Spinal Cord Stimulators
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 reoperations, making it a viable alternative
SCS-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