David H. Kidd

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.

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.

Spinal cord stimulation versus reoperation for failed back surgery syndrome: a prospective, randomized study design.

Retrospectively reported results of spinal cord stimulation compare favorably with those of neurosurgical treatment alternatives for the treatment of failed back surgery syndrome, including reoperation and ablative procedures. There has been no direct prospective comparison, however, between SCS and other techniques for pain management. Therefore, we have designed a prospective, randomized comparison of spinal cord stimulation and reoperation in patients with persistent radicular pain, with and without low back pain, after lumbosacral spine surgery. Patients selected for reoperation by standard criteria are 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 spinal cord stimulation over reoperation. Many other potentially important outcome measures will now be followed long-term as a larger overall study population accumulates.

Occult, bilateral anterior sacral and intrasacral meningeal and perineurial cysts: case report and review of the literature.

None of the more than 180 cases of anterior sacral meningocele reported in the past 150 years has been bilateral, and only two have been associated with occult intrasacral meningocele. We report a unique case of bilateral anterior sacral cysts, communicating with the subarachnoid space, associated with occult intrasacral meningeal and perineurial (Tarlovs) cysts, in an asymptomatic woman. The pertinent clinical and diagnostic imaging literature is reviewed.

Postural Changes in Spinal Cord Stimulation Perceptual Thresholds

Introduction. Spinal cord stimulation voltage thresholds have been observed to change with body position, but previously have not been characterized in detail.

Spinal cord stimulation with interleaved pulses: a randomized, controlled trial.

Objectives.  The development of multicontact electrodes and programmable, implanted pulse generators has increased the therapeutic success of spinal cord stimulation (SCS) by enhancing the ability to capture and maintain pain/paresthesia overlap. This study sought to determine if interleaved stimulation and/or frequency doubling improves pain/paresthesia overlap in patients with failed back surgery syndrome.