A multi-center analysis evaluating factors associated with spinal cord stimulation outcome in chronic pain patients.

BACKGROUND: In addition to its conventional use as a treatment for refractory neuropathic extremity pain, spinal cord stimulation (SCS) has recently emerged as a possible treatment for visceral and arthritic pain. But concurrent with the expansion of possible conditions amenable to SCS, other studies have questioned the long-term efficacy of SCS for traditional indications. These disparate findings argue strongly for the refinement of selection criteria. The purpose of this study is to identify correlates of outcome for SCS. METHODS: Data were retrospectively collected on 244 patients who underwent a SCS trial at two academic medical centers. Success was predefined as ≥50% pain relief sustained for ≥6 months. Variables analyzed for their association with outcome included demographics, location of pain, diagnosis, presence of coexisting diseases, pain descriptors, opioid and adjuvant medication use, duration and pain relief during trial, and complications. RESULTS: The presence of allodynia and/or hyperalgesia correlated with both a positive SCS trial (P = 0.01) and long-term implantation outcome (P = 0.05). History of substance abuse was associated with a negative permanent SCS outcome (P = 0.05) but bore no relationship to trial results. The variable most strongly associated with an SCS outcome was experiencing <50% pain relief during the trial, which strongly presaged a negative result (P < 0.001). CONCLUSIONS: Although weak associations with outcome were noted for several clinical variables, none was strongly associated with trial and permanent implantation results. The strongest predictor of a negative SCS outcome was obtaining <50% pain relief during the trial period.

Acute renal failure during a trial of spinal cord stimulation: theories as to a possible connection.

OBJECTIVE: This is the first case describing an episode of acute renal failure occurring during a spinal cord stimulation trial. CLINICAL PRESENTATION: A 48-year-old male with a history of hypertension and 3 prior failed spine surgeries underwent a trial of spinal cord stimulation for uncontrolled bilateral lower extremity neuropathic pain. Two days after the placement of the percutaneous stimulator lead the patient returned complaining of 3 syncopal episodes. He was found to be hypotensive and in acute renal failure with a creatinine of 8.1 and a BUN of 83. INTERVENTION: The stimulator lead was immediately removed. The patient was admitted to the intensive care unit and responded promptly to rehydration and placement of a urinary catheter. His renal and urological work-ups revealed no significant abnormalities. CONCLUSION: The development of the episode of acute renal failure may have been influenced by the secondary effects of spinal cord stimulation. Since acute renal failure has never been associated with the use of spinal cord stimulation, this singular example does not by itself demonstrate a relationship. However, if future episodes are seen, a link between the 2 events could be drawn. For now, it is not clear if the development of this patient's acute renal failure could, in part, be attributed to the use of the spinal cord stimulator or if it was merely coincidental in nature. We do feel it is useful for the clinician to understand the pathophysiologic changes associated with spinal cord stimulation and to see how, at least in theory, there could be a connection.

Psychophysical measurements during lumbar discography: a heart rate response study.

STUDY DESIGN: Prospective clinical data analysis. OBJECTIVE: To determine if heart rate (HR) response correlates with positive discography results. SUMMARY OF BACKGROUND DATA: Lumbar discography is a controversial tool for the diagnosis of discogenic low back pain. The subjective nature of discography can make data interpretation difficult, leading to false-positive and false-negative results. HR changes have been found in numerous studies to be a reliable and valid indicator of acute pain. To date, there is no study analyzing the HR response to discography-induced pain. METHODS: The HR measurements were recorded immediately preceding and after contrast injection into the each disc, and statistically correlated with the provocation of concordant pain, nonconcordant pain, and nonpainful discs. RESULTS: Discography was performed in 26 subjects with low back pain. Among 75 discograms, 26 discs elicited concordant pain, 9 provoked nonconcordant pain, and 40 elicited no pain response. There was no significant change in HR during disc stimulation for negative [no pain response (P=0.19) and nonconcordant (P=0.26)] discograms, whereas positive discograms [concordant pain (numerical rating scale> or =6/10)] were associated with a statistically significant increase in HR (P=0.000002). CONCLUSIONS: Lumbar discography induces positive HR response only in positive discograms. Although there is no immediate practical application of these results, 2 implications may deserve future research: (a) correlation of HR response with surgical and intradiscal electrotherapy treatment outcomes; (b) evaluation of HR measurement in cases of false-positive results (concordant pain on discography but no HR response).

A giant herniated disc following intradiscal electrothermal therapy.

The introduction of intradiscal electrothermal therapy for the management of discogenic back pain has been met with intense interest over the past few years. During this time there have been several noncontrolled studies published on the procedure, most of which have shown excellent outcomes but few, if any, complications. The authors describe a 29-year-old, 152-kg active duty male soldier who underwent two-level intradiscal electrothermal therapy for L4-L5 and L5-S1 discogenic pain. Before the procedure, the patient had a small L5-S1 contained herniation, with no signs of radiculitis. Postprocedure, the patient developed radicular symptoms and was noted on MRI to have a large L5-S1 disc herniation effacing the left S1 nerve root. Follow-up discography revealed a negative discogram at L4-L5. The patient proceeded to undergo a single-level lumbar fusion, which resulted in nearly complete relief of his radicular and axial low back pain. Two years post-surgery, he is off all narcotic medications and continues to work full-time as a soldier. This case illustrates both the potential benefits and complications that may be associated with intradiscal electrothermal therapy.