Hoelzer, Bryan C.

Abstract Objective Low back pain (LBP) is a leading cause of pain and disability worldwide. Recent studies demonstrate a vertebrogenic model involving the basivertebral nerve (BVN) as a cause of chronic LBP. Vertebral endplates are highly innervated by the BVN, and literature shows type 1 and 2 Modic changes at vertebral endplates are a source of vertebrogenic low back pain (VBP). As a result, intraosseous radiofrequency ablation of the BVN is a minimally invasive outpatient procedure used to treat VBP. We conducted a retrospective review of 1,145 patients that have undergone BVN ablation to assess for safety and complication management. Methods Chart reviews were conducted to obtain demographic and pre-procedural information regarding patient gender, age at the time of BVN ablation, duration of LBP, and BMI. Post-procedure information derived from chart notes included vertebral levels ablated and post-BVN ablation complications, which were categorized as increased LBP > 7 days, increased radicular pain > 7 days, lower extremity weakness, infection, vertebral compression fracture, superficial bleeding, spinal or epidural hematoma, serious neurological injury, visit to the ER, and deep vein thrombosis/clot. Results 1,145 patient charts were reviewed showing an overall complication rate of 3.2% (37 complications). Increased radicular pain was the most common complication at 2.2% (25 complications) and resolved completely in all but one patient. The overall complication rate fell to 1.1% (13 complications) when the 24 cases of transient radicular pain were not counted as adverse events. Conclusions In this multicenter retrospective review, the overall rate of complications related to BVN ablation was low (3.2%). The most common complication was temporary radicular pain that resolved with conservative care. These findings suggest that BVN ablation is a safe treatment for VBP in real-world clinical settings.

Background and Objectives: Peripheral nerve stimulation (PNS) may provide analgesia for neuropathic pain syndromes in that nerve distribution. PNS electrode placement using ultrasound (US) guidance for upper extremity pain syndromes has not been reported. Existing anchoring technology may allow permanent implantation without significant migration. Methods: Three cadaver midhumeral fresh frozen upper extremity specimens were studied. US scanning was performed, targeting electrode placement at the radial, ulnar, and median nerves. Leads were anchored in the superficial fascia. The targeted nerves were exposed by careful dissection. Visual inspection for gross nerve damage, and electrode proximity to the nerve was performed. After confirmation of adequate lead placement, 2 extremities were sutured and placed in a continuous passive motion (CPM) machine for 21 hours to simulate activity. Each electrode was assessed for migration. Results: Acceptable locations for US-guided electrode placement were: radial nerve approximately 10-14 cm superior to the lateral epicondyle; median nerve approximately 6 cm below the antecubital fossa; and ulnar nerve approximately 9 to 13 cm above the medial epicondyle. One electrode was placed at each site without difficulty. After careful exposure, visual inspection showed no gross nerve damage. Each electrode had at least 2 electrical contacts within 2 mm of the nerve sheath. At CPM termination, only the median nerve electrode on 1 cadaver extremity had migrated significantly. Conclusions: This new minimally invasive approach to lead placement requires further study to determine implantation criteria, optimal locations, anchoring techniques, and electrode design to define best clinical practice.

Abstract Objectives Lumbar spine surgery is a common procedure for treating disabling spine‐related pain. In recent decades, both the number and cost of spine surgeries have increased despite technological advances and modification in surgical technique. For those patients that have continued uncontrolled back and/or lower extremity pain following lumbar spine surgery, spinal cord stimulation (SCS) has emerged as a viable treatment option. However, the impact of lumbar spine surgical history remains largely unstudied. Specifically, the current study considers the impact of number of prior lumbar spine surgeries on pain relief outcomes following SCS implantation. Materials and Methods We queried the electronic medical record of five separate pain practices for all patients who have undergone a SCS implant between January 1, 2017, and March 1, 2020. Inclusion criteria consisted of any patients with an SCS implant who underwent a prior lumbar spine surgery. The primary outcome was the mean calculated percentage pain relief in patients based on number of prior lumbar spine surgeries. Results There was a total of 1974 total SCS implant cases identified across five separate pain clinics. There was no difference in mean calculated pain relief in patients with one prior spine surgery versus those with two or more prior spine surgeries (28.2% vs. 25.8%, adjusted β‐coefficient –3.1, 95% CI –8.9 to 2.7, p = 0.290). Similarly, when analyzing number of spine surgeries as a continuous variable, there was no association between number of spine surgeries and calculated pain relief (adjusted β‐coefficient –1.5, 95% CI –4.0 to 1.1, p = 0.257). Additionally, after patients were stratified based on waveform, there was no association between number of prior lumbar spine surgeries (analyzed both as a categorical and continuous variable) and calculated percentage pain relief. Conclusions This multicentered retrospective study found that there was no significant difference in pain scores in individuals who received SCS following one or more lumbar spine surgeries. Additionally, the waveform of the SCS device had no statistically significant impact on post‐operative pain scores following one or more lumbar spine surgeries.

Abstract Aims The aim of our study was to review the surgical literature regarding the relationship between hemoglobin A1c (HbA1c), diagnosis of diabetes mellitus (DM), and risk of postoperative surgical site infection (SSI). Methods A librarian‐assisted literature search was performed with two goals: (1) identify surgical publications related to SSI and HbA1c values, and (2) identify publications reporting infection risk with DM in spinal cord stimulation (SCS), intrathecal drug delivery systems (IDDS), and cardiovascular implantable electronic device (CIED) implantation surgeries. Published guidelines on perioperative management of DM are reviewed. Results We identified 30 studies reporting SSI and HbA1c values. The literature review indicated that for many surgical procedures, elevated HbA1c is not correlated to rate of SSI. We identified 16 studies reporting infection rates within DM cohorts following SCS, IDDS, and CIED implantation surgeries. The data reviewed did not indicate DM as an independent risk factor for SSI. Conclusion Preoperative HbA1c levels in patients with a history of DM is not a singularly sufficient tool to estimate risk of perioperative infection in SCS implantation surgery. Published guidelines on perioperative management of DM do not suggest a specific HbA1c above which surgery should be delayed; intentional perioperative glycemic control is recommended.

AbstractObjectiveThe goal of this study was to determine the frequency and clinical indications associated with implantation of single vs. dual percutaneous lead spinal cord stimulator (SCS) systems and to look further into how these leads are utilized for treatment.Materials and MethodsA retrospective cohort analysis of all patients undergoing SCS implantation between January 2001 and December 2013 with a minimum of 2 years of clinical follow‐up was performed. Number of trial leads and implanted leads was recorded. For patients with dual‐lead systems, it was noted if and when the second lead was used, along with the clinical indication for lead activation.ResultsIn the 259‐patient cohort, 15.8% (n = 41) patients underwent placement of a single‐lead system, 83.0% (n = 215) underwent placement of a dual‐lead system, and 1.2% (n = 3) underwent placement of 3‐lead systems. Placement of dual‐lead systems was similar among all indication groups. Of those patients with a dual‐lead system in place, 88.1% utilized both leads and average time to programming of the second lead was 2.3 months. The most common reason to activate the second lead was inadequate stimulation coverage. Five of the 41 patients with single‐lead systems underwent an additional surgery to implant a second lead due to inadequate stimulation with 1 lead.ConclusionsTo our knowledge this is the first descriptive analysis of the frequency of single‐ and dual‐lead SCS systems. This report indicates that dual‐lead systems are most often placed and both leads are required for optimal patient therapy.

AbstractBackgroundNew advances in spinal cord stimulation have led to improved treatment of patients suffering from chronic pain. While the overall safety of newer stimulation devices has been established, no published reports exist regarding safety considerations when these devices are implanted in patients with a preexisting cardiac device.Case ReportAn 83‐year‐old man with a history of out‐of‐hospital cardiac arrest secondary to an episode of ventricular fibrillation underwent automated implantable cardiac defibrillator placement. Concomitantly, he suffered from intractable chronic low axial back pain and was deemed a candidate for high‐frequency (10 kHz) spinal cord stimulation (SCS). Cardiac monitoring during SCS trial and implantation was performed with no interference noted. Following high‐frequency SCS implantation, the patient was observed to have significant pain relief with functional improvement.DiscussionWhile others have reported safety during traditional SCS in patients with implanted cardiac devices, this is the first case report to describe safe and effective use of high‐frequency SCS in a patient with an implanted cardiac device.

Abstract Objectives. Our purpose was to determine the incidence of surgical site infection (SSI) in cancer patients receiving an intrathecal drug delivery system (IDDS) and compare that rate with the incidence of SSI in the general population receiving an IDDS or spinal cord stimulator. We attempted to describe risk factors for SSIs in cancer patients treated with IDDS in terms of exposure to cancer treatments. Design. Retrospective review. Setting. Large tertiary care center. Patients. Cancer patients receiving an IDDS in 2006–2013. Methods. The incidence of SSI was determined according to the US Centers for Disease Control and Prevention definition. Medication regimens and current cancer treatment were investigated to identify immunocompromised patients during IDDS placement. Microbacteriology, treatment, and overall outcomes were investigated. Results. Sixty-four patients had an IDDS implanted in 2006–2013. SSI developed in four patients (6.2%). All four patients had received chemotherapy or radiotherapy within three months before implantation. Three of the three were receiving dexamethasone, and three of the four required explantation of the IDDS. Conclusion. The incidence of SSI was at the upper end of the published infection rates for IDDS. The risk of SSI may be increased in this population because of factors that alter the patient’s immune status, including concomitant corticosteroid use, radiotherapy near the SSI, and presence of immunomodulators. The identification and mitigation of certain risk factors for this population may prevent infection in future patients.

A recent publication reported the incidence of postdural puncture headache (PDPH) in conjunction with intrathecal drug delivery system (IDDS) implantation to be nearly 23 percent. Many patients responded to conservative measures but a percentage needed invasive treatment with an epidural blood patch (EBP). There is limited data to describe the technical details, success rates, and complications associated with EBP in this population. This study aims to provide a retrospective report of EBP for patients suffering from PDPH related to IDDS implantation. A chart review established a cohort of patients that required EBP in relation to a PDPH after IDDS implantation. This cohort was evaluated for demographic data as well as details of the EBP including technical procedural data, success rates, and complications. All patients received a trial of conservative therapy. Standard sterile technique and skin preparation were utilized with no infectious complications. The EBP was placed below the level of the IDDS catheter in 94% of procedures. Fluoroscopy was utilized in each case. The mean EBP volume was 18.6 cc and median time of EBP was day 7 after implant. There were no complications associated with EBP. EBP appears to be an effective intervention in this subset of PDPH patients.

Background: The principle aim of this study was to investigate the associations between heat pain (HP) perception, pain catastrophizing, and pain-related anxiety in a heterogenous cohort of community-dwelling adults with chronic pain admitted to a 3-week outpatient pain rehabilitation program. Methods: All adults consecutively admitted to an outpatient pain rehabilitation program from July 2009 through January 2011 were eligible for study recruitment (n=574). Upon admission, patients completed the Pain Catastrophizing Scale (PCS), the short version of the Pain Anxiety Symptoms Scale (PASS-20), and HP perception was assessed using a standardized quantitative sensory testing (QST) method of levels. Results: Greater PCS scores were significantly correlated with lower standardized values of HP threshold (HP 0.5) (P=0.006) and tolerance (HP 5) (P=0.003). In a multiple variable model adjusted for demographic and clinical factors known to influence HP perception, every 10-point increase in the PCS was associated with a −0.124 point change in HP 0.5 (P=0.014) and a −0.142 change in HP 5 (P=0.014) indicating that participants with higher PCS scores had lower HP thresholds and tolerances, respectively. Similarly, greater PASS-20 scores significantly correlated with lower standardized values of HP 0.5 and HP 5. In a multiple variable model, every 10-point increase in the PASS-20 was associated with a −0.084 point change in HP 0.5 (P=0.005) and a −0.116 point change in HP 5 (P=0.001) indicating that participants with higher PASS-20 scores had lower HP thresholds and tolerances, respectively. Conclusions: The findings of this study extend the use of a standardized method for assessing HP in a heterogenous sample of adults with chronic pain. Although pain catastrophizing shares significant variance with pain-related anxiety, our findings suggest that either measure would be appropriate for use in future studies that incorporate the QST method of levels.

AbstractIntroductionSpinal cord stimulators (SCS) are used to treat various chronic pain states. Establishing patient outcomes in terms of pain control, opioid medication use, and overall satisfaction is vital in maintaining SCS's role in clinical practice.MethodsAll patients who underwent SCS implantation between January 2001 and December 2011 at a tertiary academic pain medicine center were included if he or she underwent permanent cervical or thoracolumbar dorsal column SCS implantation and age was 18 or greater. For the 199 patients who met inclusion criteria, data were collected retrospectively. Preimplant information included indication for implantation, Numeric Rating Scale (NRS) score, and dose in oral morphine equivalents (OME). Postimplant NRS score was recorded at 6 months and 1 year. OME requirement and patient satisfaction were determined at 1 year postimplantation.ResultsThis data set showed an overall decrease in OME requirements and NRS scores at both 6 months and 1 year. These differences were statistically significant (P < 0.01) compared to preimplantation values. Additionally, 84.27% of patients were satisfied with their implants at 1 year. Patient outcomes were analyzed further in respect to implant indication; groups included failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), angina, and other. For all groups, there were statistically significant (P < 0.01) decreases in NRS scores at 6 months and 1 year. In the FBSS and CRPS groups, statistically significant (P < 0.02) decreases in OME usage existed.ConclusionRetrospective review of patients with spinal cord stimulators revealed OME reduction at 1 year for those patients in the FBSS and CRPS groups; patient satisfaction at 1 year and NRS score reduction at 6 months and 1 year were statistically significant for all groups.