Quantitative assessment of painful diabetic peripheral neuropathy after high-frequency spinal cord stimulation: a pilot study

OBJECTIVE

Randomized trials have demonstrated efficacy of spinal cord stimulation (SCS) for treatment of painful diabetic neuropathy (PDN). Preliminary data suggested that treatment of PDN with high-frequency SCS resulted in improvements on neurological examination. The purpose of the present study was to explore whether patients with PDN treated with high-frequency SCS would have improvements in lower-extremity peripheral nerve function.

DESIGN

Prospective cohort study in an outpatient clinical practice at a tertiary care center.

METHODS

Patients with PDN were treated with high-frequency SCS and followed up for 12 months after SCS implantation with clinical outcomes assessments of pain intensity, neuropathic symptoms, and neurological function. Small-fiber sudomotor function was assessed with the quantitative sudomotor axon reflex test (QSART), and large-fiber function was assessed with nerve conduction studies (NCS). Lower-extremity perfusion was assessed with laser Doppler flowmetry.

RESULTS

Nine patients completed 12-month follow-up visits and were observed to have improvements in lower-extremity pain, weakness, and positive sensory symptoms. Neuropathy impairment scores were improved, and 2 patients had recovery of sensory responses on NCS. A reduction in sweat volume on QSART was observed in the proximal leg but not at other sites. No significant differences were noted in lower-extremity perfusion or NCS as compared with baseline.

CONCLUSIONS

The improvement in pain relief was concordant with improvement in neuropathy symptoms. The findings from this study provide encouraging preliminary data in support of the hypothesis of a positive effect of SCS on peripheral neuropathy, but the findings are based on small numbers and require further evaluation.

TRIAL REGISTRATION

ClinicalTrials.gov ID NCT03769675.

Preoperative hemoglobin A1c and perioperative blood glucose in patients with diabetes mellitus undergoing spinal cord stimulation surgery: A literature review of surgical site infection risk

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.

The painful shoulder arthroplasty: appropriate work-up and review of interventional pain treatments

Shoulder arthroplasty is a successful surgical procedure for several conditions when patients become refractory to conservative management modalities. Unfortunately, some patients experience persistent chronic pain after shoulder arthroplasty. These individuals should undergo a comprehensive evaluation by an orthopedic surgeon to determine whether structural pathology is responsible for the pain and to decide whether reoperation is indicated. At times, a surgical solution does not exist. In these circumstances, a thorough and specific plan for the management of persistent chronic pain should be developed and instituted. In this article, we review common reasons for persistent pain after shoulder arthroplasty and outline the evaluation of the painful shoulder arthroplasty. We then provide a thorough review of interventional pain management strategies. Finally, we hypothesize developments in our field that might provide better outcomes in the future for patients suffering with chronic intractable pain after shoulder arthroplasty.

The Prevalence of Elevated Impedances and Magnetic Resonance Imaging Ineligibility Following Implantation of 10 kHz Spinal Cord Stimulation Devices: A Retrospective Review

OBJECTIVES

Spinal cord stimulation (SCS) is increasingly utilized in the treatment of multiple chronic pain conditions. However, patients will continue to experience other medical issues and the potential for future magnetic resonance imaging (MRI) needs must not be overlooked. SCS devices have device-specific MRI conditional labeling and if impedances are elevated the patient may not be able to obtain an MRI. With 10 kHz SCS devices specifically, an impedance value above 10,000 ohms (Ω) is MRI ineligible. The primary objective of this article was to report the incidence of elevated impedances with a multilumen lead design per electrode, per lead, and to describe the total number of MRI ineligible patients due to elevated impedances using 10 kHz SCS cutoff values. The secondary objective was to determine whether certain patient demographics or surgery characteristics put patients at increased risk of elevated impedances.

MATERIALS AND METHODS

We performed a retrospective review of 327 patients who were implanted with a 10 kHz SCS device between January 2015 and November 2020. Regression models were fitted to determine associations between MRI ineligibility status with clinical characteristics including age, sex, BMI, lead location, implantable pulse generator (IPG) location, and time since implant.

RESULTS

We found elevated impedances with subsequent MRI ineligibility in 13 patients (4.0%). Regression analysis did not identify any associations with MRI ineligibility and patient risk factors including age, sex, body mass index, lead location, IPG location, and follow-up time since implant.

CONCLUSION

We found the prevalence of elevated impedances above 10,000 Ω to be 4% of implanted patients. This information is important for patients and physicians alike and should be considered when device selection is occurring in the pre-operative visits.

Comparative Effectiveness of Landmark-guided Greater Occipital Nerve (GON) Block at the Superior Nuchal Line Versus Ultrasound-guided GON Block at the Level of C2: A Randomized Clinical Trial (RCT)

OBJECTIVES

The purpose of this single center, prospective randomized controlled trial was to compare clinical outcomes between an ultrasound-guided greater occipital nerve block (GONB) at the C2 vertebral level versus landmark-based GONB at the superior nuchal line.

METHODS

Patients with occipital neuralgia or cervicogenic headache were randomized to receive either a landmark-based GONB with sham ultrasound at the superior nuchal line or ultrasound-guided GONB at the C2 vertebral level with blinding of patients and data analysis investigators. Clinical outcomes were assessed at 30 minutes, 2 weeks, and 4 weeks postinjection.

RESULTS

Thirty-two patients were recruited with 16 participants in each group. Despite randomization, the ultrasound-guided GONB group reported higher numeric rating scale (NRS) scores at baseline. Those in the ultrasound-guided GONB group had a significant decrease in NRS from baseline compared with the landmark-based GONB group at 30 minutes (change of NRS of 4.0 vs. 2.0) and 4-week time points (change of NRS of 2.5 vs. -0.5). Both groups were found to have significant decreases in Headache Impact Test-6. The ultrasound-guided GONB had significant improvements in NRS, severe headache days, and analgesic use at 4 weeks when compared with baseline. No serious adverse events occurred in either group.

CONCLUSIONS

Ultrasound-guided GONBs may provide superior pain reduction at 4 weeks when compared with landmark-based GONBs for patients with occipital neuralgia or cervicogenic headache.

Systematic Literature Review of Spinal Cord Stimulation in Patients With Chronic Back Pain Without Prior Spine Surgery

OBJECTIVE

Low back pain is the leading cause of disability worldwide and one of the most common reasons for seeking healthcare. Despite numerous care strategies, patients with low back pain continue to exhibit poor outcomes. Spinal cord stimulation (SCS) is an evidence-based therapeutic modality for patients with failed back surgery syndrome. For patients without a surgical lesion or history, minimally invasive interventions that provide long-term reduction of chronic back pain are needed. Therefore, we conducted a systematic review of the evidence on SCS therapy in patients with chronic back pain who have not undergone spinal surgery.

MATERIALS AND METHODS

A systematic literature search was performed to identify studies reporting outcomes for SCS in chronic back pain patients (with or without secondary radicular leg pain) without prior surgery using date limits from database inception to February 2021. Study results were analyzed and described qualitatively.

RESULTS

A total of ten primary studies (16 publications) were included. The included studies consistently demonstrated favorable outcomes in terms of pain reduction and functional improvement following SCS therapy. Improvements also occurred in quality of life scores; however, not all studies reported statistically significant findings. Additionally, the studies reported that SCS resulted in high patient satisfaction, reductions in opioid use, and an acceptable safety profile, although these data were more limited.

CONCLUSION

Findings suggest that SCS is a promising, safe, minimally invasive, and reversible alternative option for managing chronic back pain in patients who have not undergone spinal surgery.

Antibacterial Envelope Use for the Prevention of Surgical Site Infection in Spinal Cord Stimulator Implantation Surgery: A Retrospective Review of 52 Cases

Objective

Surgical site infection in patients who undergo spinal cord stimulator implant surgery represents a significant concern in terms of increased health care costs and patient morbidity. The use of antibacterial envelopes in spinal cord stimulator implant surgeries has not been previously described. The aim of this retrospective review was to evaluate the effectiveness of the antibacterial envelope in reducing surgical site infection in spinal cord stimulator implant surgeries when used adjunctively to standard infection prevention measures.

Materials and Methods

The study included 52 patients, all of whom were implanted with a spinal cord stimulator between January 2015 and November 2020. To be included, patients were required to have had an antibacterial envelope utilized at the time of surgery. Patient records were retrospectively reviewed. All patients who received an antibacterial envelope at the time of implant surgery were included.

Results

Data was collected and analyzed on 52 permanent SCS implantations, including primary implantation (n=26) and revision surgery (n=26). All patients were at least three months post-operative from the implant surgery (average follow-up time period was 518.4 days). There were no surgical site infections reported in the 52 patient cohort.

Conclusion

Antibiotic impregnated envelopes appear to be a safe and effective modality to decrease surgical site infection risk in spinal cord stimulation implant surgeries.

Paresthesia-Based Versus High-Frequency Spinal Cord Stimulation: A Retrospective, Real-World, Single-Center Comparison

OBJECTIVE

Spinal cord stimulation (SCS) has become a common treatment modality for chronic pain of various etiologies. Over the past two decades, significant technological evolution has occurred in the SCS space, and this includes high-frequency (10 kHz) stimulation. Level I evidence exists reporting superiority of 10 kHz SCS over traditional SCS, however, conflicting reports have been published. The primary objective was to report site-collected real-world patient reported percentage improvement in pain scale (PR-PIPS) with traditional SCS and 10 kHz SCS from a single, academic medical center.

MATERIALS AND METHODS

This study was a single-center retrospective review to determine PR-PIPS of traditional SCS and 10 kHz SCS in those patients implanted for at least 12 months. Data were collected by two independent physicians not involved with the implant surgery to minimize bias in the data collection process. PR-PIPS and other clinical variables were abstracted either via chart review or via phone call for patients who were at least 12 months post-implant at the last clinical follow-up.

RESULTS

A total of 163 implanted patients (traditional stimulation n = 85; high-frequency stimulation n = 78) were identified. Twenty-two explants (traditional stimulation n = 10; high-frequency stimulation n = 12) were performed (13.5%). Seventy-five total remaining SCS implants utilizing traditional stimulation and 66 total remaining SCS implants utilizing high-frequency stimulation were included. There was no difference in PR-PIPS between traditional stimulation (50.6% ± 30.1%) and high-frequency stimulation (47.6% ± 31.5%) in the adjusted linear regression model in a variety of implant indications (p = 0.399). There was no difference in frequency of patient categorization into various thresholds of percentage pain relief based on type of stimulation. The most common reasons for explant were loss of efficacy (50.0%) and infection (40.0%) in the traditional cohort, and loss of efficacy (58.3%) in the high-frequency cohort.

CONCLUSIONS

This study adds further evidence to the published literature that successful long-term results can be achieved with SCS. Our retrospective analysis did not find a statistically significant difference in PR-PIPS between traditional stimulation and high-frequency stimulation in a variety of indications over an average follow-up of nearly two years. Notably, there were statistically significant differences in treatment indications and primary sites of pain between the two patient cohorts, and this should be considered when interpreting the results.

Infectious Complications of Dorsal Root Ganglion Stimulation: A Systematic Review and Pooled Analysis of Incidence

BACKGROUND AND OBJECTIVES

Dorsal root ganglion stimulation (DRGS) is a newer form of neuromodulation that targets the dorsal root ganglion. DRGS has superior efficacy in complex regional pain syndrome compared to spinal cord stimulation (SCS) and may have efficacy in other forms of chronic pain. While decades of safety data are available for SCS, there is less available safety information for DRGS. The objectives of this systematic review and pooled analysis of incidence are to determine the overall incidence of DRGS infections, incidence at each stage (trial vs. implant vs. revision), infection characteristics, and outcomes.

MATERIALS AND METHODS

A comprehensive search of databases from January 1980 to January 2021 was conducted.

RESULTS

Ten studies met inclusion criteria. Eight studies reported patients with trial data (n = 291), ten studies reported patients with implant data (n = 250), and seven studies reported data with revisions (n = 26). The pooled incidence of trial infections was 1.03% (95% CI 0.35-2.99%), implant infections was 4.80% (95% CI 2.77-8.20%), revision infections was 3.85% (95% CI 0.20-21.59%), and overall infections was 2.82% (95% CI 1.62-4.54%). There was a statistically significant difference in infection rates between the trial, implant, and revision stages, X² (2, N = 567) = 8.9839, p = 0.01.

CONCLUSIONS

This is the first systematic review and pooled analysis that followed PRISMA guidelines to report infectious complications of DRGS by stage (trial vs. implant vs. revision). DRGS trial appears to be low risk for infection but that risk is significantly increased with DRGS implant. Our findings highlight the need for further study of infectious complications, their risks, and optimal prophylaxis.

Differences in calculated percentage improvement versus patient-reported percentage improvement in pain scores: a review of spinal cord stimulation trials

INTRODUCTION

Spinal cord stimulation is frequently used for the treatment of intractable chronic pain conditions. Trialing of the spinal cord stimulator device is recommended to assess the patient's response to neurostimulation before permanent implantation. The trial response is often assessed by Numeric Rating Scale changes and patient-reported percentage pain improvement. Using number rating scale changes between prespinal and postspinal cord stimulation trial, a calculated percentage pain improvement can be obtained. The aim of this study was to assess the difference between calculated and patient-reported percentage improvement in pain scale during spinal cord stimulation trials.

METHODS

This study was a retrospective single center review of all spinal cord stimulation trials from January 1 2017 to July 1 2019. A total of 174 patients were included. The paired t-test was used to compare numeric pain scores obtained prestimulation versus poststimulation. The mean difference between methods (patient-reported minus calculated) was compared with zero using the 1-sample t-test. Lin's concordance correlation coefficient was computed with a 95% CI, calculated using Fisher z-transformation; and a bootstrapping approach was used to compare the concordance correlation coefficient between groups. In all cases, two-tailed tests were used with p<0.05 considered statistically significant.

RESULTS

Based on prestimulation and poststimulation numeric rating scale scores, the mean±SD calculated percentage improvement in pain scale was 54±28. The mean±SD patient-reported percentage improvement in pain scale was 59±25. The overall 95% limits of agreement for the two methods are -30% to +41%. The overall concordance correlation coefficient was 0.76 (95% CI 0.69 to 0.81).

CONCLUSION

Although the two methods are highly correlated, there is substantial lack of agreement between patient-reported and calculated percentage improvement in pain scale, suggesting that these measures should not be used interchangeably for spinal cord stimulator trial outcome assessment. This emphasizes the need for improved metrics to better measure patient response to neuromodulation therapies. Additionally, patient-reported percentage improvement in pain was found to be higher than calculated percentage improvement in pain, potentially highlighting the multidimensional experience of pain and the unpredictability of solely using Numeric Rating Scale scores to assess patient outcomes.

Explantation of 10 kHz Spinal Cord Stimulation Devices: A Retrospective Review of 744 Patients Followed for at Least 12 Months

OBJECTIVES

High-frequency 10 kHz spinal cord stimulation (10 kHz-SCS) has achieved analgesia superior to traditional SCS in a number of studies. However, there is concern regarding long-term outcomes of 10 kHz-SCS. Prior work has suggested that explant rates are higher with 10 kHz-SCS. Our primary objective was to determine the explant rate of 10 kHz-SCS in a large patient cohort from multiple centers followed for at least 12 months after implant surgery.

MATERIALS AND METHODS

We performed a retrospective chart review of all patients who received a 10 kHz-SCS implant before July 1, 2019. We abstracted patient demographics, implant date, primary site of pain, implant indication, explant date, and reason for explant. A total of 744 patients were included in the study analysis.

RESULTS

Average age of the overall cohort was 65.53 years and 407 (54.7%) were women. Average follow-up for all patients was 793 days. There were a total of 76 explants (10.2%). The most common reason for explant was loss of efficacy, which accounted for 39 explants (51.3% of total explants, 5.2% of overall cohort). Female sex and radiculopathy as the SCS indication were associated with statistically significant decreased risk of 10 kHz-SCS explant.

CONCLUSIONS

We found 10 kHz-SCS explant rates to be similar to prior reported explant rates for traditional SCS devices. Patient-related factors including female sex and radiculopathy as the primary SCS indication may be protective factors against explantation.

Spinal Cord Stimulator Infection: Approach to Diagnosis, Management, and Prevention

Spinal cord stimulation (SCS) is the most utilized invasive electrical neuromodulation treatment for the management of refractory chronic pain syndromes. Infection is one of the most dreaded complications related to SCS implantation and may prevent patients from receiving adequate pain treatment, adding to the initial cost and disability. Most SCS infections present as generator pocket infection. However, delay in diagnosis may lead to complications such as meningitis, epidural abscess, and/or vertebral osteomyelitis. Early recognition of SCS-related infections and associated complications is based on clinical suspicion, laboratory testing, and appropriate diagnostic imaging. While superficial surgical site infection following SCS implant may be treated with antibiotic therapy alone, deep infection involving implant warrants device removal to achieve cure. Duration of antimicrobial therapy depends on severity of clinical presentation and presence or absence of associated complications. Several preventive strategies can be incorporated in surgical practice to reduce the risk of SCS infection.

Peripheral Nerve Stimulation and Clinical Outcomes: A Retrospective Case Series

PURPOSE

Peripheral nerve stimulation (PNS) is a rapidly expanding field within neuromodulation; however, there is limited data on therapeutic efficacy. This study describes the indications and clinical outcomes for patients undergoing PNS for chronic pain states.

PATIENTS AND METHODS

This is a retrospective case series of adults undergoing PNS implantation from 2004 to 2017 at an academic medical center. The primary outcomes were changes in numeric rating scale (NRS) pain scores, opioid utilization in oral morphine milligram equivalent (MME), and self-reported patient functioning at 6 months postoperatively. Infectious and device-related complications were also assessed.

RESULTS

A total of 72 patients underwent PNS implantation, including 59 patients that received a preceding PNS trial (59/78; 76% progression rate) and 13 that did not receive a PNS trial. The most common indication for stimulation was occipital neuralgia (47%) followed by lower-extremity neuropathies (17%). PNS implantation was associated with 6-month reductions in pain scores (7 [6, 8] baseline vs. 4 [2, 5] 6 months; P < 0.001) and opioid utilization (eg, median 60 [31, 104] vs. 18 [0, 52] MME among those with baseline opioid use; P < 0.001). Median functional improvement was 73% (50%, 88%). Seven patients (10%) suffered a postoperative surgical site infection at a median of 50 (30, 124) days, of which five devices were removed.

CONCLUSION

Peripheral nerve stimulation was associated with reduced pain scores, lower opioid utilization, and improved patient function at 6 months. These data support PNS as a potentially effective nonopioid analgesic modality in chronic pain, though prospective multicenter evaluation is warranted to evaluate longer-term outcomes.

Pain medicine fellow neuromodulation surgical skill assessment tool: a pilot

OBJECTIVE

Spinal cord stimulation (SCS) is an evidence-based therapy for the treatment of refractory pain. Current American College of Graduate Medical Education requirements for pain medicine fellowship graduation include observation of five neuromodulation cases. Matriculating fellows have varying degrees of technical skill, training, and experience. The purpose of this study was to use an innovative skill-based assessment tool using the validated Zwisch scale to evaluate fellow surgical performance during SCS cases.

DESIGN

Cross-sectional survey SETTING: Mayo Clinic, Rochester, Minnesota.

SUBJECTS

Consultant faculty (10) in the Division of Pain Medicine and pain medicine fellows (5).

METHODS

A list of faculty-driven neuromodulation surgical objectives was formed and a rubric was created that focused on technical approach, imaging, epidural access and wound closure. Consultants who perform surgical cases were instructed to use the Zwisch scale as a guide to evaluate fellow surgical performance during a neuromodulation case. Faculty and fellows were surveyed before and after implementation of the tool to determine their satisfaction with use of the skill assessment tool.

RESULTS

The consultants reported they were more satisfied, consistent, and efficient with feedback provided to the trainee on every aspect of neuromodulation surgical cases. The improvement was most significant during the fellows' intraoperative skill assessment. The fellows indicated increased satisfaction, improved communication, and increased efficiency of feedback when the tool was utilized. The fellows reported greater intraoperative skill assessment and consistency of feedback provided.

CONCLUSIONS

The diverse nature of primary specialty backgrounds observed in pain medicine fellowship training offers a unique opportunity to assess and improve fellow skill and surgical competence in the field of neuromodulation. Both faculty and fellows reported improved satisfaction, consistency and efficiency with feedback provided. Importantly, this pilot project observed that implementation of a skill assessment tool was beneficial for both the faculty and fellow as the feedback received was viewed as strongly beneficial to the educational experience.

Spinal Stimulation for the Treatment of Intractable Spine and Limb Pain: A Systematic Review of RCTs and Meta-Analysis

OBJECTIVE

To synthesize the evidence regarding the effect of spinal stimulation (SS) vs medical therapy (MT) and the effect of newer SS technologies vs conventional SS on pain reduction in patients with intractable spine or limb pain.

METHODS

A comprehensive literature search was conducted by a reference librarian. The literature search encompassed January 1, 1995 - December 31, 2017. Reviewers worked independently to select and appraise trials. Random-effect meta-analysis and frequentist indirect comparison methods were used to compare the three interventions. Results were expressed as odds ratio (OR) or weighted mean difference (WMD) with 95% CIs.

RESULTS

We identified 12 trials enrolling 980 patients. Compared with MT, SS significantly increased the odds of reducing pain by 50% or more in three trials (OR, 13.01; 95% CI, 4.96-34.17) and significantly reduced pain as measured by visual analogue scale scores in three trials (WMD, 1.43 scale points; 95% CI, 0.16-2.71). Using the common comparator of MT, newer stimulation technology (eg, high-frequency 10 kilohertz spinal stimulation, Burst, dorsal root ganglion) was associated with increased odds of pain relief compared with conventional SS (OR, 2.07; 95% CI, 1.35-3.19).

CONCLUSIONS

In patients with intractable spine/limb pain, SS was associated with better pain reduction than MT. New stimulation technology was likely associated with better pain reduction than conventional stimulation.

The effect of spinal cord stimulation on pain medication reduction in intractable spine and limb pain: a systematic review of randomized controlled trials and meta-analysis

Objective: To synthesize the evidence regarding the effect of spinal cord stimulation (SCS) on opioid and pain medication reduction in patients with intractable spine or limb pain.

Methods: A comprehensive literature search was conducted to identify RCTs of patients with chronic back and/or limb pain of greater than one year duration. Only comparative studies were included (ie, conventional SCS vs medical therapy, conventional SCS vs high-frequency SCS) and were required to have a minimum follow-up period of 3 months. Random effect meta-an alysis was used to compare the three interventions. Results were expressed as odds ratio (OR) or weighted mean difference (WMD) with 95% confidence intervals (CI).

Results: We identified five trials enrolling 489 patients. Three of the trials reported the results as a number of patients who were able to reduce or eliminate opioid consumption in the SCS vs medical therapy group. The odds of reducing opioid consumption were significantly increased in the SCS group compared to medical therapy (OR 8.60, CI {1.93–38.30}). Two of the trials reported the results as mean medication dose reduction as measured by the Medication Quantification Scale (MQS) in the SCS group vs medical therapy group. MQS score significantly decreased in the SCS group and not in the medical group (WMD –1.97, 95% CI {–3.67, –0.27}). One trial reported a number of patients in high-frequency SCS who were able to reduce opioids vs number of patients in conventional SCS group who were able to reduce opioids. Thirty-four percent of the patients in the high-frequency group and 26% of the patients in the conventional SCS group were able to reduce opioid consumption; however, there was not a significant difference between groups (OR 1.43, 95% CI {0.74, 2.78}). This trial also quantified the opioid reduction in morphine equivalent dosage (MED). In the high-frequency SCS group, average MED decreased by 24.8 mg vs average MED decrease of 7.3 mg in the conventional SCS group. Again, the difference between groups did not reach statistical significance (–17.50, CI {–66.27, 31.27}).

Conclusions: In patients with intractable spine/limb pain, SCS was associated with increased odds of reducing pain medication consumption. However, results should be treated with caution as available data were limited, and clinical significance of these findings requires further study.

Bleeding Complications in Patients Undergoing Intrathecal Drug Delivery System Implantation

Introduction

Intrathecal drug delivery systems (IDDSs) have dramatically improved analgesia and the functional status of cancer patients and those with chronic pain states. However, given the close proximity to the neuraxis and frequent concomitant use of antiplatelet or anticoagulant medications, this intervention is not without risk. The goal of this investigation was to determine the incidence of bleeding complications following IDDS placement.

Methods

This is a retrospective review from 2005 through 2014 of adult patients undergoing IDDS implantation or revision at a tertiary care center. The primary outcome was a bleeding-related neurological complication requiring emergency medicine, neurology, or neurosurgical evaluation within 31 days.

Results

A total of 247 procedures were performed on 216 unique patients. Patients received aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) within seven days of needle placement for 64 procedures (25.9%). A preprocedural platelet count or international normalized ratio (INR) was available within 30 days for 138 procedures (55.9%). Of these, two patients had a platelet count lower than 100 x 109/L and one patient had an INR of 1.5 or higher at the time of the procedure. One neurological complication was identified (0.4%) that was not related to procedural bleeding. Similarly, three patients (1.2%) received a periprocedural red blood cell transfusion, none of which were related to procedural bleeding.

Conclusion

No cases of bleeding-related neurological complications were identified following IDDS placement or revision, including in those receiving aspirin or NSAIDs. Future investigations with larger numbers are needed to further explore the safety of antithrombotic therapy continuation or discontinuation periprocedurally.

Title: Quantifying the change of spasticity after intrathecal baclofen administration: A descriptive retrospective analysis

OBJECTIVES

Exploratory research quantifying the change of spasticity among patients who underwent baclofen intrathecal drug delivery system (IDDS) implantation.

PATIENTS AND METHODS

88 patients with a baclofen IDDS were identified. Patient characteristics, spasticity scores pre/post intrathecal baclofen test dose, and IDDS perioperative implantation records were collected. The primary outcome was to quantify the extent to which there was a change in Modified Ashworth Scores (MAS) pre/post-intrathecal baclofen test dose administration. Secondary outcomes included the prevalence of perioperative IDDS implantation complications.

RESULTS

The mean age at IDDS implant was 44.2 years (range, 19-71), and 62.5% were male. 45.5% had spasticity of spinal cord origin, 9% of cerebral origin, and 45.5% of other upper motor neuron dysfunction. Reduction of MAS in the spinal cord origin group was 2.6 (mean, 3.5 to 0.9), cerebral origin group was 2.9 (mean, 3.3 to 0.4), and other origin group was 2.5 (mean, 3.6 to 1.1). In all patients, post dural puncture headache was the most commonly reported complication at 22.7%.

CONCLUSION

This report offers novel findings documenting a quantifiable change of at least two points on the MAS before and after intrathecal baclofen test dose as statistically significant and could prove to be useful information to enhance the decision making process to proceed with intrathecal baclofen beyond assessment of functional abilities.

Utilization of Leads After Permanent Implant in Spinal Cord Stimulator Systems

OBJECTIVE

The 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 METHODS

A 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.

RESULTS

In 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.

CONCLUSIONS

To 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.

Surgical Site Infections in Cancer Patients with Intrathecal Drug Delivery Devices

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.

Bleeding Complications in Patients Undergoing Percutaneous Spinal Cord Stimulator Trials and Implantations

INTRODUCTION

Spinal cord stimulators (SCS) are indicated for the management of multiple pain states with strong evidence. Recent guidelines recommend discontinuing aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) for the described procedures. The goal of this investigation is to assess the rate of bleeding and neurologic sequelae in patients undergoing SCS trials and implantation.

METHODS

This is a retrospective review from 2005 through 2014 of all patients 18 years or older undergoing the following procedures: Percutaneous SCS implantations, SCS revisions, and SCS trials. Baseline characteristics, antiplatelet and anticoagulation medications, coagulation parameters, and procedural details were extracted. The primary outcome was the presence of a bleeding complication within 31 days of the procedure requiring emergency medicine, neurology, or neurosurgical evaluation. The neurological complication was independently categorized for its potential relationship to procedural bleeding, and periprocedural red blood cell transfusion requirements were analyzed as a secondary outcome.

RESULTS

A total of 642 percutaneous SCS procedures were performed on 421 unique patients, including 346 SCS trials, 255 SCS implantations, and 41 revision surgeries. Patients had received aspirin or NSAIDs within 7 days of needle placement for 101 procedures (15.7%). There were no bleeding or neurological complications identified in this cohort.

CONCLUSION

Although the incidence of epidural hematoma is low, the development of bleeding complications following SCS lead placement can be devastating. In the present investigation, we identified no cases of epidural hematoma following percutaneous SCS lead placement, including more than 100 patients receiving aspirin or NSAIDs. Future investigations with larger numbers are needed to better define the relationships between periprocedural aspirin and NSAID utilization and bleeding complications.