Accuracy of Template Versus Ultrasound Identification of the Reservoir Access Port of Intrathecal Drug Delivery System.

INTRODUCTION: Precise localization of the center of the reservoir access port (RAP) of intrathecal pump is a crucial step to ensure a safe refill procedure. In difficult refill cases, ultrasound guidance has been reported useful. Being more expensive and time-consuming, the purpose of the study was therefore to identify situations in which sonographic localization is more accurate than the template method, in order to restrict its use to these defined conditions. MATERIALS AND METHODS: The RAP was localized using the template provided by the manufacturer and by ultrasound guidance. The distance between the two points was measured. A distance superior to 3.5 mm, corresponding to the radius of the silicone septum of the RAP, was considered a clinically significant deviation. RESULTS: During the study period, 22 patients underwent a total of 81 refill procedures. No significant correlation was found between the distance between the two points and age, height, weight, body mass index (BMI) or abdominal perimeter. The correlation was significant between distance and pump's depth. According to the ROC curve, the sensitivity of ultrasound identification of the RAP was 69.2% and the specificity 83.3% when the pump was implanted at a depth of 10 mm. DISCUSSION: Our results are comparable to these published in the literature, pointing the usefulness of ultrasound for refill of deeply implanted pumps. Our study provides an additional element by specifying the depth from which the ultrasound seems to be superior to template. CONCLUSION: Poor accuracy in RAP identification of intrathecal pump can lead to life-threatening complications. The results of our study suggest that the localization of recessed-RAP can be improved by ultrasound in cases of pump implanted deeper than 10 mm. For more superficially implanted devices, the template method seems to be as accurate as ultrasound.

Effects of flow rate modifications on reported analgesia and quality of life in chronic pain patients treated with continuous intrathecal drug therapy.

OBJECTIVE: We compared the analgesia and the quality of life of a constant daily dose of intrathecal drug administered at different flow rates in patients treated for chronic pain. We postulate that the quality of the analgesia, at the same daily dose, will show an infusion rate dependent pattern with decreased pain at higher flow rates. PATIENTS: Twenty consecutive patients on stable intrathecal treatment were included in a double-blind three-period crossover study where the same daily dose was administered at single, double, and quadruple flow rates in a randomized sequence. OUTCOMES MEASURES: The mean daily pain score and the quality of life (EuroQol measure of health outcome [EQ-5D]) were measured following each flow rate change, after 1 week of stabilization. Results. Visual analog scale (VAS) scores remained unchanged with all flow rates. Compared with the lowest flow rate, the EQ-5D index decreased with double and even more with quadruple flow rate, suggesting a clinically relevant worsening of the health state with higher flow rates. Adverse events were equally distributed in all groups. CONCLUSION: Pain VAS did not significantly change with flow rate. This is consistent with preclinical data showing very limited increase in drug distribution in the cerebrospinal fluid with much larger flow rate augmentation. However, the quality of life decreased consistently as the flow rate increased. This was entirely due to a worsening of the pain and anxiety dimension of the EQ-5D questionnaire, caused presumably by a slight increase in pain rather than adverse events. We suggest that at higher flow rates increased drug dilution results in a decreased effect at the receptor site.

Spinal Cord Stimulation vs. Conventional Medical Management: A Prospective, Randomized, Controlled, Multicenter Study of Patients with Failed Back Surgery Syndrome (PROCESS Study).

Introduction. Since its first application in 1967, numerous case series indicate that spinal cord stimulation (SCS) is an effective treatment for the management of failed back surgery syndrome (FBSS). However, only one randomized controlled trial has demonstrated that SCS provides more effective pain relief than re-operation and conventional medical management. The PROCESS randomized, controlled, multicenter trial aims to assess the clinical effectiveness and cost-effectiveness of SCS when added to conventional medical management compared to conventional medical management alone in patients with FBSS. Methods/Design. A total of 100 FBSS patients with predominantly neuropathic leg pain will be recruited from 12 centers and randomized to receive either conventional medical management alone or in combination with SCS for a period of 24 months. Patients will be evaluated at 1, 3, 6, 9, 12, 18, and 24 months. At the 6-month visit, patients will be classified as successful (≥  50% pain relief in the legs) or unsuccessful (< 50% pain relief in the legs). If the results of the randomized treatment are unsuccessful, patients can cross over to the alternative treatment arm. Discussion. This paper highlights the rationale, design, methods, and challenges of an ongoing prospective, randomized, controlled, multicenter clinical trial that has been undertaken to obtain conclusive evidence of the clinical efficacy and cost-effectiveness of an SCS system in patients with FBSS.