Paresthesia-Free Dorsal Root Ganglion Stimulation: An ACCURATE Study Sub-Analysis.

INTRODUCTION: ACCURATE, a randomized controlled trial comparing dorsal root ganglion (DRG) stimulation to spinal cord stimulation, showed that DRG stimulation is a safe and effective therapy in individuals with lower extremity chronic pain due to complex regional pain syndrome (CRPS) type I or II. Investigators noted that DRG stimulation programming could be adjusted to minimize, or eliminate, the feeling of paresthesia while maintaining adequate pain relief. The present study explores treatment outcomes for DRG subjects who were paresthesia-free vs. those who experienced the sensation of paresthesia, as well as the factors that predicted paresthesia-free analgesia. METHODS: A retrospective analysis of therapy outcomes was conducted for 61 subjects in the ACCURATE study who received a permanent DRG neurostimulator. Outcomes of subjects who were paresthesia-free were compared to those who experienced paresthesia-present therapy at 1, 3, 6, 9, and 12-month follow-ups. Predictor variables for the presence or absence of paresthesias with DRG stimulation were also explored. RESULTS: The percentage of subjects with paresthesia-free pain relief increased from 16.4% at 1-month to 38.3% at 12-months. Paresthesia-free subjects generally had similar or better outcomes for pain severity, pain interference, quality of life, and mood state as subjects with paresthesia-present stimulation. Factors that increased the odds of a subject feeling paresthesia were higher stimulation amplitudes and frequencies, number of implanted leads, and younger age. CONCLUSIONS: Some DRG subjects achieved effective paresthesia-free analgesia in the ACCURATE trial. This supports the observation that paresthesia is not synonymous with pain relief or required for optimal analgesia with DRG stimulation.

Effect of a novel fixation method for spinal cord stimulators.

INTRODUCTION: Spinal cord stimulation is a well-established treatment for recalcitrant pain syndromes such as failed back surgery syndrome. Techniques minimizing surgical time and incision size and increasing lead stability are of great value to both the patient and implanting physician. We present a consecutive case series review of ten permanent percutaneous spinal cord implants utilizing a novel lead fixation device. The purpose of this case series review is to present initial findings of the minimized incision size and thoughts surrounding the new device and technique. CASE SERIES REPORT: Ten cases were performed utilizing the new device (fiXate) and technique. Incision size was dictated by adequate visualization of the fascial stratum as well as technical working space required for lead fixation and redirection to the generator pocket. Each spinal cord stimulator lead was affixed to the thoracodorsal fascia utilizing the novel device. DISCUSSION: In this consecutive series, the average midline incision size was 2.2 cm (range = 1.9-2.6 cm) which is greatly minimized through the use of the device. Not only may fiXate directly affect incision size, operating room and anesthesia time may also be lessened due to the semiautomated nature of the device. Of the cases performed, there were no complications or adverse events. Of note, there have been no reports of lead migrations during this case series, the average follow-up time being 18 weeks (range 11-26 weeks). CONCLUSION: These data suggest a new method of fixation can be utilized for percutaneous spinal cord stimulation that allows a reduction in incision size. Intuitively, reduction in incision size is relevant with regard to tissue morbidity and may also have implications with regard to infection. Use of the device may also reduce operating room and anesthesia time as well as provide greater stability than standard suture.

Novel approach for peripheral subcutaneous field stimulation for the treatment of severe, chronic knee joint pain after total knee arthroplasty.

OBJECTIVE: The objective of this study is to present a novel approach for the treatment of severe, chronic knee joint pain following total knee arthroplasty utilizing peripheral subcutaneous field stimulation and discuss the role of this treatment modality in patients with symptoms that are refractory to conventional pharmacologic, surgical, and physical therapies. MATERIALS AND METHODS: Presented are two case reports of patients with chronic intractable knee pain where peripheral nerve stimulation via a permanent neurostimulating implant was introduced successfully. Both patients presented with persistent knee pain, for greater than one year, after having had total knee arthroplasty. The patients' symptoms failed to be alleviated by a variety of interventions including non-steroidal anti-inflammatory drugs (NSAIDS), oral antidepressants, membrane stabilizers, opioids, physical therapy, surgical revisions, manipulation under anesthesia, local anesthetic patches, and transcutaneous electrical nerve stimulation. In each case, direct stimulation of the knee was achieved utilizing a peripheral nerve stimulator via a periarticular approach. RESULTS: Neuromodulation daily has produced both significant pain relief and functional improvement. Significant decreases in pain visual analog scale (VAS) scores and improvement in functional capacity were observed during the stimulation trial and during the follow-up after permanent implantation. The mean VAS score changed dramatically. CONCLUSIONS: Introduction of a peripheral subcutaneous field stimulation directly to the painful knee area is a novel and simple procedure that was extremely effective for the relief of pain and may provide a breakthrough in the treatment of chronic intractable knee pain following total knee arthroplasty. The periarticular approach has several advantages, including only small incisions over the lateral and medial knee, proximal thigh and abdomen resulting in minimal strain on the lead array with flexion and extension contributing to overall stability of this system.

Therapy Habituation at 12 Months: Spinal Cord Stimulation Versus Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome Type I and II.

The ACCURATE randomized, controlled trial compared outcomes of dorsal root ganglion (DRG) stimulation versus tonic spinal cord stimulation (SCS) in 152 subjects with chronic lower extremity pain due to complex regional pain syndrome (CRPS) type I or II. This ACCURATE substudy was designed to evaluate whether therapy habituation occurs with DRG stimulation as compared to SCS through 12-months. A modified intention-to-treat analysis was performed to assess percentage pain relief (PPR) and responder rates at follow-up visits (end-of-trial, 1, 3, 6, 9, 12-months postpermanent implant) for all subjects that completed trial stimulation (DRG:N = 73, SCS:N = 72). For both groups, mean PPR was significantly greater at end-of-trial (DRG = 82.2%, SCS =0 77.0%) than all other follow-ups. Following permanent DRG system implantation, none of the time points were significantly different from one another in PPR (range = 69.3-73.9%). For the SCS group, PPR at 9-months (58.3%) and 12-months (57.9%) was significantly less than at 1-month (66.9%). The responder rate also decreased for the SCS group from 1-month (68.1%) to 12-months (61.1%). After stratifying by diagnosis, it was found that only the CRPS-I population had diminishing pain relief with SCS. DRG stimulation resulted in more stable pain relief through 12-months, while tonic SCS demonstrated therapy habituation at 9- and 12-months. Trial Registration: The ACCURATE study was registered at ClinicalTrials.gov with Identifier NCT01923285. PERSPECTIVE: This article reports on an ACCURATE substudy, which found that long-term therapy habituation occurred at 12-months with SCS, but not DRG stimulation, in patients with CRPS. The underlying mechanisms of action for these results remain unclear, although several lines of inquiry are proposed.

Splanchnic block at T11 provides a longer relief than celiac plexus block from nonmalignant, chronic abdominal pain.

AIM: Neural blockade at the celiac plexus is less specific compared with splanchnic nerve block. This retrospective study compares duration and potency of celiac versus splanchnic block. Patients & methods: Analyzed were data of 16 consecutive patients with visceral abdominal nonmalignant pain treated using both celiac plexus and T11 splanchnic block. RESULTS: Improvement in pain scores was from 7.24 ± 1.0 to 4.1 ± 2.1 for celiac, and 7.8 ± 0.8 to 2.9 ± 2.1 for splanchnic at 4 weeks. Duration of the splanchnic nerve block was superior, median of 56 days versus only 21 days for celiac plexus block. Conclusion: T11 bilateral splanchnic block provided significantly longer relief from chronic nonmalignant abdominal pain, than celiac plexus block (p = 0.001). Reduction in pain severity was more with splanchnic compared with celiac block (p = 0.029).