Richard B. North

Spinal cord stimulation versus conventional medical management for neuropathic pain: A multicentre randomised controlled trial in patients with failed back surgery syndrome

Abstract Patients with neuropathic pain secondary to failed back surgery syndrome (FBSS) typically experience persistent pain, disability, and reduced quality of life. We hypothesised that spinal cord stimulation (SCS) is an effective therapy in addition to conventional medical management (CMM) in this patient population. We randomised 100 FBSS patients with predominant leg pain of neuropathic radicular origin to receive spinal cord stimulation plus conventional medical management (SCS group) or conventional medical management alone (CMM group) for at least 6 months. The primary outcome was the proportion of patients achieving 50% or more pain relief in the legs. Secondary outcomes were improvement in back and leg pain, health‐related quality of life, functional capacity, use of pain medication and non‐drug pain treatment, level of patient satisfaction, and incidence of complications and adverse effects. Crossover after the 6‐months visit was permitted, and all patients were followed up to 1 year. In the intention‐to‐treat analysis at 6 months, 24 SCS patients (48%) and 4 CMM patients (9%) (p < 0.001) achieved the primary outcome. Compared with the CMM group, the SCS group experienced improved leg and back pain relief, quality of life, and functional capacity, as well as greater treatment satisfaction (p ⩽ 0.05 for all comparisons). Between 6 and 12 months, 5 SCS patients crossed to CMM, and 32 CMM patients crossed to SCS. At 12 months, 27 SCS patients (32%) had experienced device‐related complications. In selected patients with FBSS, SCS provides better pain relief and improves health‐related quality of life and functional capacity compared with CMM alone.

Spinal cord stimulation versus repeated lumbosacral spine surgery for chronic pain: a randomized, controlled trial.

OBJECTIVE:Persistent or recurrent radicular pain after lumbosacral spine surgery is often associated with nerve root compression and is treated by repeated operation or, as a last resort, by spinal cord stimulation (SCS). We conducted a prospective, randomized, controlled trial to test our hypothesis that SCS is more likely than reoperation to result in a successful outcome by standard measures of pain relief and treatment outcome, including subsequent use of health care resources. METHODS:For an average of 3 years postoperatively, disinterested third-party interviewers followed 50 patients selected for reoperation by standard criteria and randomized to SCS or reoperation. If the results of the randomized treatment were unsatisfactory, patients could cross over to the alternative. Success was based on self-reported pain relief and patient satisfaction. Crossover to the alternative procedure was an outcome measure. Use of analgesics, activities of daily living, and work status were self-reported. RESULTS:Among 45 patients (90%) available for follow-up, SCS was more successful than reoperation (9 of 19 patients versus 3 of 26 patients, P < 0.01). Patients initially randomized to SCS were significantly less likely to cross over than were those randomized to reoperation (5 of 24 patients versus 14 of 26 patients, P = 0.02). Patients randomized to reoperation required increased opiate analgesics significantly more often than those randomized to SCS (P < 0.025). Other measures of activities of daily living and work status did not differ significantly. CONCLUSION:SCS is more effective than reoperation as a treatment for persistent radicular pain after lumbosacral spine surgery, and in the great majority of patients, it obviates the need for reoperation.

The effects of spinal cord stimulation in neuropathic pain are sustained: a 24-month follow-up of the prospective randomized controlled multicenter trial of the effectiveness of spinal cord stimulation

OBJECTIVEAfter randomizing 100 failed back surgery syndrome patients to receive spinal cord stimulation (SCS) plus conventional medical management (CMM) or CMM alone, the results of the 6-month Prospective Randomized Controlled Multicenter Trial of the Effectiveness of Spinal Cord Stimulation (i.e., PROCESS) showed that SCS offered superior pain relief, health-related quality of life, and functional capacity. Because the rate of crossover favoring SCS beyond 6 months would bias a long-term randomized group comparison, we present all outcomes in patients who continued SCS from randomization to 24 months and, for illustrative purposes, the primary outcome (>50% leg pain relief) per randomization and final treatment. METHODSPatients provided data on pain, quality of life, function, pain medication use, treatment satisfaction, and employment status. Investigators documented adverse events. Data analysis included inferential comparisons and multivariate regression analyses. RESULTSThe 42 patients continuing SCS (of 52 randomized to SCS) reported significantly improved leg pain relief (P < 0.0001), quality of life (P ≤ 0.01), and functional capacity (P = 0.0002); and 13 patients (31%) required a device-related surgical revision. At 24 months, of 46 of 52 patients randomized to SCS and 41 of 48 randomized to CMM who were available, the primary outcome was achieved by 17 (37%) randomized to SCS versus 1 (2%) to CMM (P = 0.003) and by 34 (47%) of 72 patients who received SCS as final treatment versus 1 (7%) of 15 for CMM (P = 0.02). CONCLUSIONAt 24 months of SCS treatment, selected failed back surgery syndrome patients reported sustained pain relief, clinically important improvements in functional capacity and health-related quality of life, and satisfaction with treatment.

Low‐grade cerebral astrocytomas: Survival and quality of life after radiation therapy

Of 77 patients with supratentorial Grades I and II astrocytoma diagnosed from January 1975 to December 1984, 66 were treated with postoperative radiation therapy. The patients received a tumor dose of 5000 to 5500 cGy in 180 cGy fractions, five fractions per week, over 5.5 to 6 weeks. Overall actuarial survival at 2, 5, and 10 years was 71%, 55%, and 43%, respectively. Progression‐free survival at 2, 5, and 10 years was 69%, 50%, and 39%, respectively. Survival for patients receiving postoperative radiation therapy in the range of 4500 to 5900 cGy was 78% and 66% at 2 and 5 years, respectively. Quality of life was determined at two points in time: 1 to 2 years postoperatively, and at last follow‐up (2‐12 years postoperatively). The occurrence of mental retardation was specifically addressed in long‐term survivors, and was observed in 50% of children. Overall, however, 80% of short‐term survivors and 67% of long‐term survivors were intellectually and physically intact, without major neurologic deficit. Specific prognostic factors were assessed by multivariate analysis. Improved survival was observed with young patients, females, normal preoperative mental status, surgical resection (versus biopsy alone), involvement of only one lobe with tumor, and a history of preoperative seizures. A weighted prognostic factor score derived from these observations permits a clinically useful assessment of risk for individual patients.

Specificity of diagnostic nerve blocks: a prospective, randomized study of sciatica due to lumbosacral spine disease

&NA; Temporary nerve blocks using local anesthetic are employed extensively in the evaluation of pain problems, particularly lurnbosacral spine disease. Their specificity and sensitivity in localizing anatomic sources of pain have never been studied formally, however, and so their diagnostic and prognostic value is questionable. There have been anecdotal reports of relief of pain by temporary blocks directed to areas of pain referral, as opposed to areas of documented underlying pathology; but there has been no study to define the frequency or magnitude of this effect. We have examined the specificity and sensitivity of a battery of local anesthetic blocks in a series of 33 patients with a chief complaint of sciatica, attributable in all cases to spinal disease (radiculopathy, with some clinical features of arthropathy). As determined by blinded patient analog ratings in randomized sequence, three different nerve blocks were significantly more effective than control lumbar subcutaneous injection of an identical volume of 3 ml of 0.5% bupivacaine (P < 0.05). Not only paraspinal lumbosacral root blocks and medial branch posterior primary ramus blocks (at or proximal to the pathology), but also sciatic nerve blocks (distal or collateral to the pathology) produced temporary relief in a majority of patients. This confirmed the study hypothesis that false positive results are common, and specificity is low. For sciatic nerve blocks, specificity was between 24% and 36%. Patterns of responses specific to the established diagnosis of radiculopathy (i.e., root block most effective) had sensitivities between 9% and 42%. Statistical analysis of clinical and technical prognostic factors revealed that the only association with pain relief by any block were the effects of other blocks. The strongest association was between relief by sciatic nerve block and relief by medial branch posterior primary ramus (facet) block (P = 0.001, odds ratio 16.0). There were no associations between the results of blocks and clinical findings (history, physical examination, diagnostic imaging) in these patients, chosen for their homogeneous clinical presentation and absence of functional signs. Our findings indicate a limited role for uncontrolled local anesthetic blocks in the diagnostic evaluation of sciatica and referred pain syndromes in general. Negative blocks or a pattern of responses may have some predictive value, but isolated, positive blocks are non‐specific. This lack of specificity may, however, be advantageous in therapeutic applications.

Cost-effectiveness analysis of spinal cord stimulation in treatment of failed back surgery syndrome

This article presents an analysis of the medical costs of spinal cord stimulation (SCS) therapy in the treatment of patients with failed back surgery syndrome (FBSS). We compared the medical costs of SCS therapy with an alternative regimen of surgeries and other interventions. Externally powered (external) and fully internalized (internal) SCS systems were considered separately. Clinical management models of each of the therapy alternatives were derived from the clinical literature, retrospective data sets, expert opinion, and published diagnostic and therapy protocols. No value was placed on pain relief or improvements in the quality of life that successful SCS therapy can generate. We found that by reducing the demand for medical care by FBSS patients, SCS therapy can lower medical costs. On average, given current screening and efficacy rates, SCS therapy pays for itself within 5.5 years. For those patients for whom SCS therapy is clinically efficacious, the therapy pays for itself within 2.1 years.

Radiofrequency lumbar facet denervation: analysis of prognostic factors

&NA; Percutaneous radiofrequency lumbar facet denervation has been in use as a treatment for intractable, mechanical low back pain for over 2 decades. A number of case series have been reported with high rates of success in selected patients; however, there has been limited objective outcome assessment, long‐term follow‐up, and analysis of prognostic factors. We have reviewed our experience with diagnostic lumbar facet blocks and percutaneous radiofrequency denervation at a mean follow‐up interval of 3.2 years. Long‐term outcome has been assessed by disinterested third party interview. Of 82 patients selected for these procedures, 56 had undergone prior low back surgery. Following diagnostic medial branch posterior primary ramus blocks, 42 reported at least 50% relief of pain and proceeded to radiofrequency denervation. Forty‐five percent of patients undergoing denervation reported at least 50% relief of pain at long‐term follow‐up. Among the 40 patients who only underwent temporary blocks, 13% reported relief (i.e., spontaneous improvement or placebo effect) by at least 50% at long‐term follow‐up). By multivariate statistical analysis, patients undergoing bilateral blocks for bilateral or axial symptoms were significantly more likely to achieve temporary relief, and to proceed to permanent denervation. There was no difference, however, between the long‐term results of bilateral denervation for bilateral or axial pain and those of unilateral denervation for unilateral pain. There was no significant difference in the rate of response between the 56 patients who had undergone prior lumbosacral spine surgery and the 26 who had not. There were no complications from the procedure. Percutaneous radiofrequency lumbar facet denervation has a moderate overall long‐term yield, with no morbidity in our experience, and so remains a clinically useful technique in properly selected patients. Diagnostic blocks, used routinely in patient selection, may lack specificity in predicting long‐term‐response to denervation.

Spinal Cord Stimulation for Axial Low Back Pain : A Prospective, Controlled Trial Comparing Dual With Single Percutaneous Electrodes

Study Design. A prospective, controlled, clinical trial comparing single and dual percutaneous electrodes in the treatment of axial low back pain from failed back surgery syndrome. Objectives. To clarify technical requirements and test the hypothesis that placing two linear arrays in parallel, thereby doubling the number of contacts, improves outcome. Summary of Background Data. Technical improvements have enhanced outcomes of spinal cord stimulation for chronic axial low back pain. Dual, parallel electrodes reportedly improve these outcomes. Methods. Acting as their own controls, 20 patients who passed screening with single, 4-contact electrodes received permanent dual, 4-contact electrodes with 7- or 10-mm intercontact distances at the same vertebral level(s). We quantified and compared the technical and clinical results of the single and dual electrodes, adjusting stimulation parameters to specific psychophysical thresholds. Results. Single electrodes provided significant (P < 0.01) advantages in patient- and computer-calculated ratings of pain coverage by paresthesias and in the scaled amplitude necessary to cover the low back, compared with dual 7-mm electrodes. Slight advantages without statistical significance were observed for the single over the dual 10-mm electrodes. Amplitude requirements were significantly lower for the single electrode than for either dual electrode. At long-term follow-up, 53% of patients met the criteria for clinical success. Conclusions. While we observed disadvantages for dual electrodes in treating axial low back pain, we achieved technical success with single or dual electrodes in most patients and maintained this success clinically with dual electrodes in 53%.

A Prospective, Randomized Study of Spinal Cord Stimulation versus Reoperation for Failed Back Surgery Syndrome: Initial Results

Spinal cord stimulation (SCS) has been reported to be effective treatment for the failed back surgery syndrome in a number of retrospective case series. Its retrospectively reported results compare favorably with those of neurosurgical treatment alternatives, such as reoperation and ablative procedures. There has been no direct prospective comparison, however, between SCS and other techniques for pain management. We have undertaken a prospective, randomized comparison of SCS and reoperation in patients with persistent radicular pain, with and without low back pain, following lumboscral spine surgery. Patients selected for reoperation by standard criteria have been randomly assigned to initial treatment by one or the other technique. The primary outcome measure is the frequency of crossover to the alternative procedure, if the results of the first have been unsatisfactory after 6 months. Results for the first 27 patients reaching the 6-month crossover point show a statistically significant (p = 0.018) advantage for SCS over reoperation. This is one of many potentially important outcome measures, which are to be followed long-term as a larger overall study population accrues.

The Appropriate Use of Neurostimulation of the Spinal Cord and Peripheral Nervous System for the Treatment of Chronic Pain and Ischemic Diseases: The Neuromodulation Appropriateness Consensus Committee

The Neuromodulation Appropriateness Consensus Committee (NACC) of the International Neuromodulation Society (INS) evaluated evidence regarding the safety and efficacy of neurostimulation to treat chronic pain, chronic critical limb ischemia, and refractory angina and recommended appropriate clinical applications.