Abram H. Burgher

Novel 10-kHz High-frequency Therapy (HF10 Therapy) Is Superior to Traditional Low-frequency Spinal Cord Stimulation for the Treatment of Chronic Back and Leg PainThe SENZA-RCT Randomized Controlled Trial

Background:Current treatments for chronic pain have limited effectiveness and commonly known side effects. Given the prevalence and burden of intractable pain, additional therapeutic approaches are desired. Spinal cord stimulation (SCS) delivered at 10 kHz (as in HF10 therapy) may provide pain relief without the paresthesias typical of traditional low-frequency SCS. The objective of this randomized, parallel-arm, noninferiority study was to compare long-term safety and efficacy of SCS therapies in patients with back and leg pain. Methods:A total of 198 subjects with both back and leg pain were randomized in a 1:1 ratio to a treatment group across 10 comprehensive pain treatment centers. Of these, 171 passed a temporary trial and were implanted with an SCS system. Responders (the primary outcome) were defined as having 50% or greater back pain reduction with no stimulation-related neurological deficit. Results:At 3 months, 84.5% of implanted HF10 therapy subjects were responders for back pain and 83.1% for leg pain, and 43.8% of traditional SCS subjects were responders for back pain and 55.5% for leg pain (P < 0.001 for both back and leg pain comparisons). The relative ratio for responders was 1.9 (95% CI, 1.4 to 2.5) for back pain and 1.5 (95% CI, 1.2 to 1.9) for leg pain. The superiority of HF10 therapy over traditional SCS for leg and back pain was sustained through 12 months (P < 0.001). HF10 therapy subjects did not experience paresthesias. Conclusion:HF10 therapy promises to substantially impact the management of back and leg pain with broad applicability to patients, physicians, and payers.

Ultrasound‐Guided Permanent Implantation of Peripheral Nerve Stimulation (PNS) System for Neuropathic Pain of the Extremities: Original Cases and Outcomes

OBJECTIVE Our objective is to describe our experience applying a minimally invasive, ultrasound-assisted technique for peripheral nerve stimulation (PNS) trial and permanent implantation in patients with neuropathic extremity pain. DESIGN Retrospective case series and review of the literature. Setting. Tertiary referral center and academic medical center. PATIENTS Patients with upper or lower extremity neuropathic pain resistant to other therapies who responded to an ultrasound-guided peripheral nerve block at a proximal location. Interventions. Ultrasound-assisted through-the-needle placement of percutaneous neurostimulation electrodes on target major peripheral nerves for fully percutaneous trial, staged trial or permanent implantation of PNS system. A PNS trial period of 3-7 days was used. OUTCOME MEASURES Pain relief at last follow-up, complications, therapeutic limitations due to technique as applied. Results. Six of eight (75%) patients and 7/9 (78%) peripheral nerves had a successful trial and underwent permanent PNS system implantation using a minimally invasive, ultrasound-assisted technique from November 2007 to December 2008. All but one patient with an implanted PNS system had > or =50% pain relief at last follow-up and 3/7 (43%) permanent systems were associated with > or =80% relief. Loss of paresthesia required revision to dual-lead systems in upper extremity radial nerve PNS. Infection led to explant in one case. CONCLUSIONS In a small series of patients, a minimally invasive, ultrasound-assisted technique for PNS trial, and permanent PNS implantation proved feasible. Patients without adequate analgesia during neurostimulation trial avoided surgical incision and those undergoing permanent implantation were not subjected to the potential morbidity associated with nerve dissection.

Comparison of 10-kHz High-Frequency and Traditional Low-Frequency Spinal Cord Stimulation for the Treatment of Chronic Back and Leg Pain: 24-Month Results From a Multicenter, Randomized, Controlled Pivotal Trial

BACKGROUND: Pain relief with spinal cord stimulation (SCS) has focused historically on paresthesias overlapping chronically painful areas. A higher level evidence supports the use of SCS in treating leg pain than supports back pain, as it is difficult to achieve adequate paresthesia coverage, and then pain relief, in the low back region. In comparison, 10-kHz high-frequency (HF10 therapy) SCS therapy does not rely on intraoperative paresthesia mapping and remains paresthesia-free during therapy. OBJECTIVE: To compare long-term results of HF10 therapy and traditional low-frequency SCS. METHODS: A pragmatic randomized, controlled, pivotal trial with 24-month follow-up was conducted across 11 comprehensive pain treatment centers. Subjects had Visual Analog Scale scores of ≥5.0/10.0 cm for both back and leg pain, and were assigned randomly (1:1) to receive HF10 therapy or low-frequency SCS. The primary end point was a responder rate, defined as ≥50% back pain reduction from baseline at 3 months with a secondary end point at 12 months (previously reported). In this article, 24-month secondary results are presented. Non-inferiority was first assessed, and if demonstrated the results were tested for superiority. RESULTS: In the study, 198 subjects were randomized (101 HF10 therapy, 97 traditional SCS). One hundred seventy-one subjects (90 HF10 therapy, 81 traditional SCS) successfully completed a short-term trial and were implanted. Subjects averaged 54.9 ± 12.9 years old, 13.6 ± 11.3 years since diagnosis, 86.6% had back surgery, 88.3% were taking opioid analgesics. At 3 months, 84.5% of implanted HF10 therapy subjects were responders for back pain and 83.1% for leg pain, and 43.8% of traditional SCS subjects were responders for back pain and 55.5% for leg pain (P < .001 for both back and leg pain comparisons, non-inferiority and superiority). At 24 months, more subjects were responders to HF10 therapy than traditional SCS (back pain: 76.5% vs 49.3%; 27.2% difference, 95% CI, 10.1%-41.8%; P < .001 for non-inferiority and superiority; leg pain: 72.9% vs 49.3%; 23.6% difference, 95% CI, 5.9%-38.6%; P < .001 for non-inferiority and P = .003 for superiority). Also at 24 months, back pain decreased to a greater degree with HF10 therapy (66.9% ± 31.8%) than traditional SCS (41.1% ± 36.8%, P < .001 for non-inferiority and superiority). Leg pain also decreased to a greater degree with HF10 therapy (65.1% ± 36.0%) than traditional SCS (46.0% ± 40.4%, P < .001 for non-inferiority and P = .002 for superiority). CONCLUSION: This study demonstrates long-term superiority of HF10 therapy compared with traditional SCS in treating both back and leg pain. The advantages of HF10 therapy are anticipated to impact the management of chronic pain patients substantially. ABBREVIATIONS: IPG, implantable pulse generator MCID, minimal clinically important difference PI, permanent implant ODI, Oswestry Disability Index SCS, spinal cord stimulation VAS, Visual Analog Scale

Dorsal root ganglion stimulation yielded higher treatment success rate for complex regional pain syndrome and causalgia at 3 and 12 months: a randomized comparative trial

Abstract Animal and human studies indicate that electrical stimulation of dorsal root ganglion (DRG) neurons may modulate neuropathic pain signals. ACCURATE, a pivotal, prospective, multicenter, randomized comparative effectiveness trial, was conducted in 152 subjects diagnosed with complex regional pain syndrome or causalgia in the lower extremities. Subjects received neurostimulation of the DRG or dorsal column (spinal cord stimulation, SCS). The primary end point was a composite of safety and efficacy at 3 months, and subjects were assessed through 12 months for long-term outcomes and adverse events. The predefined primary composite end point of treatment success was met for subjects with a permanent implant who reported 50% or greater decrease in visual analog scale score from preimplant baseline and who did not report any stimulation-related neurological deficits. No subjects reported stimulation-related neurological deficits. The percentage of subjects receiving ≥50% pain relief and treatment success was greater in the DRG arm (81.2%) than in the SCS arm (55.7%, P < 0.001) at 3 months. Device-related and serious adverse events were not different between the 2 groups. Dorsal root ganglion stimulation also demonstrated greater improvements in quality of life and psychological disposition. Finally, subjects using DRG stimulation reported less postural variation in paresthesia (P < 0.001) and reduced extraneous stimulation in nonpainful areas (P = 0.014), indicating DRG stimulation provided more targeted therapy to painful parts of the lower extremities. As the largest prospective, randomized comparative effectiveness trial to date, the results show that DRG stimulation provided a higher rate of treatment success with less postural variation in paresthesia intensity compared to SCS.

Minimally Invasive Retrieval of Knotted Nonstimulating Peripheral Nerve Catheters

Objective: Continuous peripheral nerve blockade is rapidly becoming the technique of choice for the management of postoperative orthopedic pain. However, the insertion of perineural catheters may be associated with complications, including catheter kinking and knotting. A knotted catheter may be difficult or impossible to remove at the patient bedside, requiring surgical excision under general anesthesia. We describe a previously unreported minimally invasive technique of retrieving knotted peripheral nerve catheters and avoiding the need for surgical intervention. Although the described technique has been used by interventional radiologists for the removal of knotted intravascular devices, it has not been previously described for the retrieval of knotted perineural catheters. Brief Report: The Mayo Clinic Acute Pain Service database was queried and patients identified with knotted peripheral nerve catheters during the 3-year period from January 2003 to January 2006. The medical records of all identified patients were retrospectively reviewed and details of catheter placement including catheter type and location, size (gauge), ease of placement, distance threaded, and duration of use recorded. During the study period, 5,964 nonstimulating peripheral nerve catheters were placed. Of these, 8 (0.13%) patients experienced catheter knotting resulting in difficult or impossible catheter removal at the bedside. Seven (88%) of the 8 catheters were successfully removed by using a minimally invasive technique of catheter retrieval using guided fluoroscopy. The remaining catheter was removed at the bedside with patient repositioning. Conclusions: The knotting of peripheral nerve catheters is a relatively uncommon phenomenon, occurring in only 0.13% of patients. However, because the use of perineural catheters has increased within anesthesia practice, clinicians may begin to encounter these complications with greater frequency. Practitioners should be aware of surgical alternatives, including guided-fluoroscopic techniques, when simple catheter traction or tension proves unsuccessful at the patient bedside.

Subcutaneous peripheral nerve stimulation with inter-lead stimulation for axial neck and low back pain: case series and review of the literature.

Objectives:  While pain in the extremities often responds to treatment using spinal cord stimulation (SCS), axial pain is notoriously refractory to SCS. Interest in subcutaneous peripheral nerve stimulation (SQ PNS) as an alternative to SCS has emerged, but the most appropriate electrode locations and neurostimulator programming techniques are not yet clear.

Introduction of infection control measures to reduce infection associated with implantable pain therapy devices.

Introduction:  Implantable pain therapy devices for chronic pain include spinal cord stimulators (SCS) and intrathecal drug delivery systems (IDDS). A number of different complications can occur after implantation of these devices, but among the most serious is infection. Based on Centers for Disease Control and Prevention guidelines for prevention of surgical site infection, published literature on infection risk with implantable pain therapy devices, and recommendations from groups within our own our institution, we introduced infection control measures for all patients receiving either SCS or IDDS.

Transforaminal Epidural Clonidine Versus Corticosteroid for Acute Lumbosacral Radiculopathy due to Intervertebral Disc Herniation

Study Design. Randomized, double-blinded clinical trial. Objective. To compare effi cacies of two active therapies for chronic low back pain. Summary of Background Data. Radicular pain may result from intervertebral disc herniation. Clonidine has demonstrated analgesic and anti-infl ammatory activity in animal studies on nerve injury. Extensive clinical experience supports neuraxial clonidine’s safety. Methods. Patients with approximately 3 months of low back pain and leg pain due to intervertebral disc herniation were randomized to transforaminal epidural injection(s) of 2% lidocaine and either clonidine (200 or 400 g) or triamcinolone (40 mg). Patients received one to three injections administered at about 2 weeks apart. Patients, investigators, and study coordinators were blinded to the treatment. The primary outcome was an 11-point Pain Intensity Numerical Rating Scale at 1 month. Other outcomes included Patient Global Impression of Change and functional measures. Results. Of the 33 patients screened and randomized, 26 enrolled, of which 11 received clonidine and 15 triamcinolone. Both groups showed signifi cant improvement in pain score at 2 weeks and 1 month compared with baseline (P 0.05). The corticosteroid group showed additional functional improvement at 1 month with respect to clonidine (P 0.022). There was no difference between groups for primary outcome. However, as target enrollment was not reached, we cannot say with confi dence that the two treatments would be expected to result in similar short-term pain relief. Adverse effects were common in both groups, but there were no serious complications. Conclusions. Radicular pain due to intervertebral disc herniation improved rapidly with transforaminal epidural injection of either clonidine or triamcinolone. Corticosteroid resulted in greater functional improvement, with unclear differences in analgesia. Future

Thoracic spinal cord stimulation for post-ablation cardiac pain in a patient with permanent pacemaker.

Background:  Spinal cord stimulation (SCS) is increasingly utilized for inoperable, intractable chest pain because of ischemia. Because patients with ischemic heart disease commonly have permanent cardiac pacemakers (PPM) or automated implantable cardio‐defibrillators (AICD), concurrent use of SCS and PPM or AICD may grow. Interference between SCS and PPM or AICD devices is potentially dangerous and has been previously reported.