Comparison of Tonic vs. Burst Spinal Cord Stimulation During Trial Period.

BACKGROUND: Spinal cord stimulation (SCS) is a well-known treatment in patients with failed back surgery syndrome (FBSS). Burst stimulation is a recently developed stimulation modality that seems to be superior to tonic stimulation. METHODS: This observational multicenter study compared tonic and burst stimulation during a trial period in patients with FBSS or radiculopathy. All the patients enrolled underwent two weeks of tonic stimulation followed by another two weeks of BurstDR stimulation, without randomization. The primary outcome was the reduction of pain in the legs and back. Health-related quality of life (EQ-5D) and the pain catastrophizing scale (PCS) were assessed before and after the trial. Patients were reevaluated after 12 months. RESULTS: We recruited 23 patients, 57% of whom had FBSS and 43% had radiculopathies. Five patients failed both the tonic and burst stimulation trials. While tonic stimulation reduced leg pain (p < 0.05), the burst mode added an extra pain reduction (ΔNRS 1.2 ± 1.5) (p < 0.01). No significant reduction in back pain was found (p 0.29). Pain on movement was reduced only by BurstDR (p < 0.01). Both stimulation modalities increased EQ-5D and reduced PCS from the baseline (p < 0.0001). At the end of the SCS trial phase, 26% patients chose tonic SCS, while 74% preferred burst. On 12-month follow-up examination, the benefits recorded at the end of the trial were maintained. CONCLUSIONS: Burst stimulation confers a greater reduction in leg pain intensity at rest and on movement. Reducing axial pain is still a challenge. Further studies are needed in order to provide each patient with the most appropriate stimulation paradigm.

Effects of Multiple Waveforms on Patient Preferences and Clinical Outcomes in Patients Treated With Spinal Cord Stimulation for Leg and/or Back Pain.

OBJECTIVES: We present the results of a prospective, randomized, crossover, single-blind, study in which each patient is in control of himself. The aim was to evaluate subperception-based (SP-SCS) waveforms in previously implanted spinal cord stimulation (SCS) patients with leg and/or back pain due to failed back surgery syndrome, who experienced only paresthesia-based stimulation (PB-SCS). Patients with PB-SCS experience in SCS was 4.7 years (SD 2.9). MATERIALS AND METHODS: We enrolled 28 consecutive patients. Treatment consisted of seven days of PB-SCS, followed by a randomized, crossover phase to test SP-SCS waveforms (burst or 1 kHz frequency, seven days each). A maximum of three-day washout period separated each stimulation program. RESULTS: Statistically significant pain relief was maintained using both SP-SCS waveforms, as indicated by the differences between the pre-PB-SCS numeric pain rating score (mean 9) and the pain score after using the burst program (pain relief 52%) or the 1 kHz program (pain relief 51%). There was no statistically significant superiority among PB-SCS, burst, and 1 kHz stimulation. Overall, 50% of patients preferred PB-SCS, 42% chose to move to SP-SCS stimulation, one patient was unable to give feedback, and one patient was unsuccessful with any type of stimulation. Overall, SCS has shown to be successful in pain relief and the patients switched to a SP-SCS waveform only for having higher pain relief. CONCLUSIONS: There was a high heterogeneity regarding waveform preference, with patients who preferred to feel the tingling sensation and those who chose a SP-SCS option, mainly for greater pain relief. In general, SCS is successful, resulting in high pain relief, improvements in quality of life, and little depression. Overall, 42% patients benefited from the novel SP-SCS stimulation waveforms.

Effectiveness of opioid analgesics in chronic noncancer pain.

BACKGROUND: There is general agreement about the need to perform a screening test to assess the risk of opioid misuse prior to starting a long-term opioid treatment for chronic noncancer pain. The evidence supporting the effectiveness of opioid long-term treatment is weak, and no predictors of its usefulness have been assessed. OBJECTIVE: The aim of this study was to assess the effect on pain and quality of life of chronic opioid treatment, and detect the possible predictors of its effectiveness. METHODS: This observational, prospective study was conducted in 2 Italian Pain Relief Units on 77 patients affected by intractable chronic pain. Patients were submitted to psycho-logical tests, investigating the individual pain experience, risk of opioid misuse, mood states, quality of life, and personality characteristics prior to starting treatment and at 2,4, and 6-month follow-up. RESULTS: Both maximum and habitual pain, as measured with VAS, underwent a statistically significant reduction at 2, 4, and 6-month follow-up. In multivariate analysis, lower scores in the Pain Medication Questionnaire (PMQ) were predictive of a major reduction in maximum VAS (P = 0.005). Both low PMQ and MMPI-cynicism scores were predictive of habitual VAS decrease (P = 0.012 and P = 0.028, respectively). CONCLUSION: The results indicate that pain relief significantly improved over a 6-month period of opioid treatment, together with quality of life. The outcome was better in patients with a pretreatment low risk of opioid misuse, low scores in the Cynicism scale of MMPI-2, and no aberrant drug behaviors at follow-up. Therefore, a psychological screening and support is crucial for a good outcome of opioid therapy for chronic noncancer pain patients.

Risk assessment of opioid misuse in italian patients with chronic noncancer pain.

Objective. Opioid therapy in patients with chronic noncancer pain must be preceded by evaluation of the risk of opioid misuse. The aim of this study was to evaluate the predictive validity of the Italian translation of the Pain Medication Questionnaire (PMQ) and of the Diagnosis Intractability Risk and Efficacy Score (DIRE) in chronic pain patients. Design. 75 chronic noncancer pain patients treated with opioids were enrolled and followed longitudinally. Risk of opioid misuse was evaluated through PMQ, DIRE, and the physician's clinical evaluation. Pain experience and psychological characteristics were assessed through specific self-report instruments. At follow-ups, pain intensity, aberrant drug behaviors, and presence of the prescribed opioid and of illegal substances in urine were also checked. Results. PMQ demonstrated good internal consistency (Cronbach's α = 0.77) and test-retest reliability (r = 0.86). Significant correlations were found between higher PMQ scores and the number of aberrant drug behaviors detected at 2-, 4-, and 6-month follow-ups (P < 0.01). Also the DIRE demonstrated good predictive validity. Conclusions. The results obtained with specific tools are more reliable than the clinician's evaluation alone in predicting the risk of opioid misuse; regular monitoring and psychological intervention will contribute to improving compliance and outcome of long-term opioid use.

Improvement in psychosocial outcomes in chronic pain patients receiving intrathecal morphine infusions.

BACKGROUND: When conventional multimodal analgesic therapy is unsuccessful, more aggressive analgesic treatments are required for patients with intractable chronic pain. Despite extensive clinical experience with implanted morphine pumps, there is still controversy regarding the psychosocial effects of this invasive analgesic therapy. In this prospective study, we evaluated the impact of intrathecal (IT) morphine infusions on pain perception and psychosocial functionality. A secondary objective of this pilot study was to assess the effect of IT morphine infusion on the patient's level of functional activity. METHODS: Thirty patients with chronic nonmalignant pain that failed to respond to multimodal analgesic regimens were evaluated using the McGill Pain Questionnaire before and at 3-, 12-, and 24-mo intervals after implantation of an IT morphine infusion pump. At each clinic visit, the patient's level of pain was assessed using an 11-point visual analog scale, with 0 = no pain and 10 = worse pain imaginable. The mean initial morphine infusion rate was 0.23 +/- 0.14 mg/day (with a range from 0.09 to 0.75 mg/day) and was subsequently adjusted to maintain their pain score at a value <50% of the initial value. Adverse side effects and complications, as well as activity levels, were recorded at each clinic visit. RESULTS: Both evaluative and affective components of the pain assessment demonstrated a significant improvement over the 24-mo study period. The evaluative component of the McGill Pain Questionnaire improved 66%, the affective component 59%, and the sensory component 32%. The average morphine infusion rate increased to 0.44 +/- 0.29, 0.66 +/- 0.39, and 0.80 +/- 0.45 mg/day at the 3-, 12-, and 24-mo follow-up intervals (P < 0.05). The reduced level of chronic pain leads to improved social, work, and family relationships and quality of life. Among 13 patients of working age, 12 returned to work full time, and among 17 retired patients, 14 had a reduced need for assistance. CONCLUSIONS: IT infusion of morphine using an implantable pump was helpful in improving psychosocial function in patients with intractable pain that had failed to respond to standard multimodal analgesic therapy.