Potential Cost Savings with 60-day Peripheral Nerve Stimulation Treatment in Chronic Axial Low Back Pain.

INTRODUCTION: Chronic axial low back pain (CLBP) that is not responsive to medication management or physical therapy often requires significant clinical intervention. Several interventional pain management options exist, including a 60-day peripheral nerve stimulation (PNS) treatment. This economic evaluation investigated the potential for projected cost savings associated with prioritizing 60-day PNS treatment relative to a 'standard of care' (SOC) approach (where patients do not have access to 60-day PNS). METHODS: A decision tree (supervised machine learning) model tracked treatment progression across two hypothetical cohorts of US patients with CLBP in whom non-interventional options were ineffective (Cohort A: treatment starting with 60-day PNS followed by any additional interventional and surgical treatments versus Cohort B: standard of care interventional and surgical treatments without access to 60-day PNS). Treatment efficacy estimates were based on published success rates. Conditional on treatment failure, up to two additional interventions were considered within the 12-month time frame in both cohorts. SOC treatment options included epidural injection, radiofrequency ablation (RFA), basivertebral nerve ablation (BVNA), PNS permanent implant (PNS-PI), spinal cord stimulator (SCS) trial/implant, and spinal fusion surgery. Treatment choice probabilities in both cohort algorithms were based on clinician interviews. Costs were based on national Medicare reimbursement levels in the ambulatory surgery center (ASC) setting. Savings reflected the difference in projected costs between cohorts. A Monte Carlo simulation and sensitivity analyses were conducted to generate confidence intervals and identify important inputs. RESULTS: The treatment algorithm which prioritized initial 60-day PNS treatment was projected to save $8056 (95% CI $6112-$9981) per patient during the first year of interventional treatment relative to the SOC approach. CONCLUSIONS: Use of the 60-day PNS treatment as an initial interventional treatment in patients with CLBP may result in significant savings for Medicare. Projected savings may be even larger for commercial payers covering non-Medicare patients.

Is Response to a Pre-implant Diagnostic Peripheral Nerve Block Associated With Efficacy After Peripheral Nerve Stimulation Implantation? A Ten-Year Enterprise-Wide Analysis.

OBJECTIVES: This study aimed to assess whether patient response to targeted diagnostic peripheral nerve block before peripheral nerve stimulator (PNS) device implantation is associated with efficacy after PNS implantation. MATERIALS AND METHODS: The electronic medical records from the Mayo Clinic Enterprise (three quarternary care medical centers and additional satellite medical centers) were reviewed to identify patients who underwent PNS implantation between January 2014 and January 2023. A primary outcome of interest was to assess whether administration of a preimplant diagnostic peripheral nerve block predicted pain relief at three months and six months after temporary and permanent PNS implantation. Another primary outcome was to investigate whether there was an association between the pain relief from a preimplant diagnostic peripheral nerve block and pain relief after three and six months after temporary or permanent PNS therapy. Linear regression analysis was conducted for outcomes of interest. RESULTS: Of 193 eligible patients who underwent PNS therapy, a total of 173 patients were included in the final analysis and were stratified into either the temporary PNS cohort (n = 112) or the permanent PNS cohort (n = 61). Overall, 77.5% of all patients (134/173) underwent a preimplant diagnostic peripheral nerve block and reported a mean percentage relief of 70.1 ± 27.0 from the diagnostic block. Of patients in the temporary PNS cohort, there was no difference in postimplant percentage pain relief between patients who received a diagnostic block (n = 93) and control patients (n = 19) at three months (35.4 ± 36.0 vs 49.8 ± 36.1, respectively; ß -14.45, 95% CI -32.98 to 4.07, p = 0.125) or at six months (23.3 ± 30.8 vs 45.7 ± 40.0, respectively; ß -22.39, 95% CI -46.86 to 2.08, p = 0.072). Of patients in the permanent PNS cohort, there was no difference in postimplant percentage pain relief between patients who received a diagnostic block (n = 41) and control patients (n = 20) at three months (42.4 ± 34.3 vs 43.2 ± 42.4, respectively; ß -0.79, 95% CI -23.56 to 21.99, p = 0.945) or at six months (44.3 ± 35.0 vs 38.8 ± 40.9, respectively; ß 5.42, 95% CI -20.04 to 30.88, p = 0.669). Pain relief from preimplant diagnostic blocks was associated with postimplant pain relief from temporary PNS at three months (ß 0.33, 95% CI 0.04-0.61, p = 0.025). However, pain relief from preimplant diagnostic blocks did not predict postimplant pain relief from temporary PNS at six months, or permanent PNS at three months and six months. CONCLUSIONS: Administration of a diagnostic block is not associated with superior pain relief at three or six months after PNS implantation to that of an approach without diagnostic block. Pain relief from a diagnostic block may potentially predict short-term pain relief after temporary PNS therapy, although future prospective studies are warranted to evaluate the prognostic utility of diagnostic blocks.

Incidence of Temporary Peripheral Nerve Stimulator Lead Tip Retention: A Retrospective Review of 80 Lead Placements.

OBJECTIVES: The primary objective of this study was to determine the current rate of lead fracture during temporary percutaneous peripheral nerve stimulator (PNS) lead removal at the Mayo Clinic Rochester Division of Pain Medicine. MATERIALS AND METHODS: A retrospective review of electronic medical records was performed for patients implanted with a temporary percutaneous PNS device between January 1, 2018, and December 31, 2020. Patients were included if they underwent temporary percutaneous PNS system implant, with planned lead removal at 60 days. Data collection included date of implant, diagnosis, peripheral nerve target(s), number of leads, and lead tip status at the time of removal (intact vs fractured). RESULTS: Fifty patients underwent a total of 80 temporary percutaneous PNS leads placed during the time frame analyzed. Of the 80 temporary percutaneous PNS leads implanted, there were five lead fractures at the time of intentional lead removal. CONCLUSIONS: This retrospective review of 50 patients with 80 temporary percutaneous PNS leads implanted for chronic peripheral neuropathic pain resulted in a 6.25% rate of retained lead fragment at the time of lead removal by the provider at the end of 60-day treatment. This fracture and retention rate is consistent with previous published retrospective data on PNS, which has shown a 3% to 21% lead fracture rate during intentional lead removal.

Treatment of Ulnar Neuropathic Pain with Peripheral Nerve Stimulation: Two Case Reports.

Ulnar neuropathy is a condition that manifests with symptoms of neuropathic pain, numbness, tingling, and even possible motor deficits in the ulnar distribution of the arm. This debilitating painful condition may be refractory to conservative, pharmacologic, and surgical interventions. Peripheral nerve stimulation (PNS) technology has advanced significantly in recent years allowing for conditions such as ulnar neuropathy to be treated in a minimally invasive manner. Here we report the first case reports in the literature (to our knowledge) of two patients with intractable ulnar neuropathy who underwent minimally invasive PNS Bioventus implants. Both patients experienced at least 75% pain relief based on NRS scores at 6 months after ulnar nerve PNS implantation. The patients also experienced significant improvement in functional outcomes, including return to employment, ability to perform activities of daily living without any impairment, and improved quality of life measures. While the results presented in our two case reports are promising, we only provide observational data over a 6 to 15-month period post-implantation. Future well-powered, large-scale, and long-term randomized controlled trials are warranted to determine efficacy and long-term pain and functional outcomes from PNS therapy for treatment of ulnar neuropathy.

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.

Spinal region corticosteroid injections are not associated with increased risk for influenza.

BACKGROUND CONTEXT: Spinal region corticosteroid injections (CSI) are intended to act locally to relieve radicular or axial back pain, however some systemic absorption occurs, potentially placing recipients at risk for immunosuppressive effects of corticosteroids. No previous studies examine whether patients undergoing spinal region CSI are at increased risk for viral infections, particularly influenza-a common viral illness with potentially serious consequences, especially for patients with multimorbidity. PURPOSE: To examine odds of influenza in patients who received spinal region CSI compared to matched controls. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: Adults (n=9,196) who received a spinal CSI (epidural, facet, sacroiliac, paravertebral block) during influenza seasons occurring from 2000 to 2020 were 1:1 matched to controls without spinal CSI. OUTCOME MEASURES: The primary outcome was odds of influenza diagnosis in spinal CSI patients compared to matched controls. Predetermined subgroup analyses examined odds of influenza diagnosis based on vaccination status and injection location. METHODS: An institutional database was queried to identify patients that received spinal CSI during influenza season (September 1 to April 30) from 2000 to 2020. Patients were matched by age, sex, and influenza vaccination status to controls without spinal CSI within the specified influenza season. Influenza diagnosis was ascertained using International Classification of Disease codes and data was analyzed using multiple logistic regression adjusted for comorbidities associated with increased risk for influenza. RESULTS: A total of 9,196 adults (mean age 60.8 years, 60.4% female) received a spinal CSI and were matched to a control. There were no increased odds of influenza for spinal CSI patients as compared to matched controls (OR 1.13, [95% CI, 0.86-1.48]). When subgroups were examined, there were also no increased odds of influenza for spinal CSI patients based on immunization status (unvaccinated or vaccinated) or spinal injection location (epidural or non-epidural). CONCLUSIONS: Spinal region CSI was not associated with increased odds of influenza or reduced vaccine efficacy. This is reassuring given the analgesic and functional restoration benefits of these injections. Assessing risk of viral infection associated with spinal CSI is particularly relevant in the era of the COVID-19 pandemic, and further work is needed to address this issue.

Perioperative Opioid Consumption and Clinical Outcomes in Surgical Patients With a Pre-existing Opioid-Based Intrathecal Drug Delivery System.

BACKGROUND: Intrathecal drug delivery systems (IDDS) have been utilized for over 3 decades for management of chronic pain and spasticity. Patients with IDDS may present for surgical procedures unrelated to the IDDS device, although data are limited regarding perioperative outcomes. METHODS: This is a historical matched cohort study conducted between January 1, 2007 and December 31, 2016 of patients with an opioid-based IDDS versus matched control patients undergoing surgery excluding interventional pain procedures. Patients in the IDDS group were matched with up to 2 patients without an IDDS. Multivariable regression analyses were utilized to assess differences in the primary outcome of cumulative perioperative opioid consumption (ie, intraoperative and postanesthesia care unit [PACU] opioid consumption), and opioid consumption during the first 24 and 72 postoperative hours. Postoperative clinical outcomes were also assessed including escalating oxygen requirements, naloxone administration, pain-sedation mismatch, and perioperative pain service consultation. RESULTS: A total of 321 surgeries were included, 112 with IDDS and 209 controls, with median (interquartile range [IQR]) age of 57 (49-64) years. Compared to matched controls, patients with an IDDS had greater perioperative opioid consumption (median [IQR] oral morphine milligram equivalents [OME] of 110 [60-163] vs 93 [IQR, 53-142]; adjusted multiplicative increase 1.28 [95% confidence interval {CI}, 1.03-1.59]; P = .026). IDDS patients also had greater opioid consumption in the first 24 and 72 postoperative hours (multiplicative increases of 2.23 [95% CI, 1.36-3.63], P = .001, and 2.46 [95% CI, 1.41-4.32], P = .002, respectively). There were no significant differences in postoperative oxygen requirements, naloxone administration, or pain-sedation mismatch. Inpatient pain medicine consultation was more frequent in IDDS patients compared to controls (51.8% vs 6.2%; P < .001). CONCLUSIONS: Patients with opioid-based IDDS received more perioperative opioids and were more likely to receive postoperative pain service consultation compared to matched controls. There were no significant differences in clinical safety outcomes, suggesting tolerance for higher opioid doses. Further research is warranted to optimize perioperative outcomes in those with IDDS.

Pre-Operative Assessment of Patients Undergoing Spinal Cord Stimulation for Refractory Angina Pectoris.

Spinal cord stimulation (SCS) is used to treat a variety of chronic pain conditions refractory to more conservative management including refractory angina pectoris. We identified 31 patients who underwent SCS implantation for the indication of refractory angina at a single institution from 2003 through 2018. Sixteen patients were male, and 15 were female. Average age was 53.9 years. Prior to SCS implantation, all patients had at least one coronary angiogram. Ten (32.3%) patients had undergone percutaneous coronary intervention, and four (12.9%) had undergone coronary artery bypass grafting. Thirty patients (96.7%) were currently using anti-angina medications. Twenty-six patients (83.9%) were on antiplatelet or anticoagulant agents at the time of SCS evaluation. Spinal cord stimulation implanters must perform a comprehensive evaluation incorporating appropriate multidisciplinary care particularly in patients with refractory angina given their cardiovascular comorbidities. It is important to have baseline data (e.g., pain scores, nitroglycerin consumption, frequency of angina episodes, and a questionnaire, such as the Seattle Angina Questionnaire) to compare with follow-up data to help define treatment success. We report a single institution's pre-operative experience for patients undergoing SCS for refractory angina to illustrate unique pre-operative SCS considerations in this chronic pain population.

The Use of the Seattle Angina Questionnaire in Patients Who Underwent Spinal Cord Stimulation for Refractory Angina Pectoris.

BACKGROUND: The Seattle Angina Questionnaire (SAQ) is a self-administered questionnaire used in cardiac patients to quantify angina based on five scales: physical limitation scale, anginal stability scale, anginal frequency scale, treatment satisfaction scale, and the disease perception scale. Here we report the use of the SAQ to assess angina symptoms in 18 patients who underwent spinal cord stimulation (SCS) for refractory angina pectoris (RAP) at the Mayo Clinic. METHODS: Electronic health records were searched to find patients who underwent SCS for the treatment of RAP at a single institution from 2003 to 2018. Eligible patients were asked to participate in a phone survey that included the SAQ. RESULTS: Out of 13 patients who still had their implant, six (46%) had minimal physical limitations. Ten patients (76.9%) had favorable anginal frequency scores, defined as minimal or mild. Out of the five patients who had their device removed, one (20%) had minimal physical limitations and three (60%) had favorable anginal frequency scores. There was a high treatment satisfaction score for both those with their implant in place and those with the device removed. CONCLUSION: The SAQ is useful as a comprehensive measure specific to patients with RAP assessing function, pain, and satisfaction. The utilization of this tool pre- and post-operatively may provide additional information to analyze the effectiveness of SCS for RAP.

Examining Use of Low-Dose Ketamine Infusions During the Postoperative Period: A Retrospective Study Comparing Opioid-Tolerant and Nonopioid-Tolerant Patients.

Ketamine is a well-known anesthetic that has been used since the 1970s. Despite its ubiquitous use as a postoperative analgesic, no studies have described dosing differences between opioid-tolerant (OT) and nonopioid-tolerant (NOT) patients or determined optimal dosing. The primary aim of this study was to assess whether OT and NOT patients had significant differences in ketamine infusion dosing requirements. We also aimed to measure the overall incidence of psychotomimetic adverse effects associated with low-dose ketamine infusions. We hypothesized that NOT patients would have lower ketamine infusion dosing requirements and a higher incidence of psychotomimetic adverse effects compared with OT patients. We performed a retrospective chart review and showed that the percentages of OT and NOT patients experiencing psychotomimetic adverse effects were similar (15.5% vs 15.3%; P=.93) and that increasing age was the only factor associated with increased odds of experiencing a psychotomimetic adverse effect potentially associated with ketamine (odds ratio, 1.29 [95% CI, 1.11-1.50]; P=.001). Optimal subanesthetic ketamine infusion dosing could not be established, and further research in this area may be warranted.

A three-dimensional computed tomography study to determine the ideal method for fluoroscopically-guided bone marrow aspiration from the iliac crest.

Bone marrow aspiration (BMA) through the iliac crest is potentially unsafe due to the vicinity of neurovascular structures in the greater sciatic notch. Our objective was to investigate the safety of a recently described BMA technique, specifically a trajectory from the posterior superior iliac spine (PSIS) to the anterior inferior iliac spine (AIIS). We conducted a chart review of 260 patients, analyzing three-dimensional reconstructed computed tomography images of the pelvis and sacrum to validate that this new approach offers a wide safety margin from the greater sciatic notch. Analysis of three-dimensional computed tomography scans demonstrated that the PSIS to AIIS trajectory never crossed the greater sciatic notch. The trajectory was noted to be at least one cm away from the greater sciatic notch in all measurements. The new trajectory entered the PSIS at 25.29 ± 4.34° (left side) and 24.93 ± 4.15° (right side) cephalad from the transverse plane, and 24.58 ± 4.99° (left side) and 24.56 ± 4.67° (right side) lateral from the mid-sagittal plane. The area of bone marrow encountered with the new approach was approximately 22.5 cm2. Utilizing the same CT scans, the trajectory from the traditional approach crossed the greater sciatic notch in all scans, highlighting the potential for violating the greater sciatic notch boundary and damaging important neurovascular structures. Statistically significant sex-related differences were identified in needle trajectory angles for both approaches. We conclude that based on this three-dimensional computed tomography study, a trajectory from the PSIS to the AIIS for BMA may offer a wide safety margin from the greater sciatic notch.

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.

Peripheral Nerve Stimulation: A New Treatment for Meralgia Paresthetica.

BACKGROUND: Meralgia paresthetica is a condition caused by entrapment of the lateral femoral cutaneous nerve that leads to paresthesia along the anterolateral portion of the thigh. Because of advancements in neuromodulation, peripheral nerve stimulation (PNS) has been considered a new treatment option for meralgia paresthetica. Newer PNS technology targets peripheral nerves directly yet in a minimally invasive manner. We report a case in which a PNS device provided more than 12 months of complete pain relief in a patient with meralgia paresthetica and helped the patient avoid a neurolysis procedure. CASE PRESENTATION: A 57-year-old male presented to clinic with a 6-year history of "painful numbness [and] burning" along the right lateral thigh. He rated his pain as 8 out of 10, which decreased to a rating of 2 out of 10 with the use of gabapentin, but unwanted side effects motivated him to seek alternative treatment. On the basis of his history, physical exam, and imaging results, he was diagnosed with meralgia paresthetica. He was offered neurolysis; however, after seeing a pain specialist, he agreed to the implantation of a SPRINT peripheral nerve stimulator. After the implantation procedure, his pain reduced to 0 out of 10, and his quality of life improved, with better sleep and less somnolence. The device was removed after 60 days, as planned. He continued to have complete resolution of pain at 12 months after the date of device implantation. CONCLUSION: With recent advancements, PNS can be used to treat meralgia paresthetica in an effective yet minimally invasive manner. As newer PNS technology becomes more familiar to physicians and pain specialists, it is likely to be used as a mainstay treatment for meralgia paresthetica.

Sex-Related Differences in Symptoms and Psychosocial Outcomes in Patients With Fibromyalgia: A Prospective Questionnaire Study.

OBJECTIVE: To investigate sex-related differences in patients with fibromyalgia (FM) in terms of demographic characteristics and clinical features, including tender point count (TPC), mood disorders, sleep problems, FM symptom severity, fatigue, cognitive dysfunction, and quality of life (QOL). PATIENTS AND METHODS: We studied 668 consecutive patients with FM (606 women) from May 1, 2012, to November 30, 2013. Validated questionnaires assessed outcomes of depression (Patient Health Questionnaire-9), anxiety (Generalized Anxiety Disorder-7), sleep problems (Medical Outcomes Study Sleep Scale), FM symptom severity (Revised Fibromyalgia Impact Questionnaire), fatigue (Multidimensional Fatigue Inventory), cognitive dysfunction (Multiple Ability Self-report Questionnaire), and QOL (36-Item Short Form Health Survey). Nonparametric Mann-Whitney U and Pearson χ2 tests were used to compare continuous and categorical outcome measures, respectively, between men and women. Linear regression models were performed for all continuous dependent variables, adjusting for age, body mass index, ethnicity, marital status, and highest education level completed. P<.05 was considered statistically significant. The Benjamini-Hochberg procedure was used to adjust for multiple comparisons. RESULTS: Multiple linear regression analysis revealed a significant association of female sex and greater TPC (P<.001), lower overall FM symptom severity (lower overall Revised Fibromyalgia Impact Questionnaire score; P=.03), and higher QOL subscale score for vitality (36-Item Short Form Health Survey vitality subscale score; P=.02). After adjustment for multiple comparisons, only the association between female sex and greater TPC remained significant. There were no sex-related differences in demographic characteristics, depression, anxiety, sleep problems, FM symptom severity, cognitive dysfunction, and QOL. CONCLUSION: A higher TPC may be associated with female sex in patients with FM. The assumption of other sex-based differences in the clinical presentation of FM was not supported in our study.

Advancement in Neuromodulation Technology with the Innovation of Design-Specific Peripheral Nerve Stimulators: Sural Nerve Stimulation for Radiculopathy.

BACKGROUND: Peripheral nerve stimulation (PNS) is a form of neuromodulation that is used to treat chronic and refractory neuropathic pain. Peripheral nerve stimulation was first described in the early 1960s when Shelden implanted a PNS device for trigeminal neuralgia. Despite PNS being known since the 1960s, technology designed specifically for PNS was lacking. Within the past few years, design-specific PNS devices have become widely available, with favorable efficacy and safety profiles. Here we report a case of design-specific PNS that provided two years of pain relief in a patient with lower extremity neuropathic pain. CASE PRESENTATION: A 53-year-old female with a history of congenital lumbar meningocele status post-L4-L5 laminectomy presented to the Mayo Clinic for treatment of foot pain that began three days after her laminectomy. She experienced a 6/10 burning, tingling sensation in the lateral dorsal portion of her right foot and posterolateral calf in addition to allodynia that prevented her from wearing shoes. She failed gabapentin, amitriptyline, cannabis, transforaminal epidural steroid injections, and two spinal cord stimulator trials. The patient ultimately underwent implantation of a right sural nerve stimulator, resulting in a 50% improvement in pain and functionality at two-year follow-up. CONCLUSIONS: This report emphasizes the recent development of design-specific PNS devices and their successful use in this patient. Peripheral nerve stimulation technology and applications have diminished the role of spinal cord stimulation devices used for the periphery. Peripheral nerve stimulation should be considered for patients with isolated extremity pain, especially in those with spinal abnormalities (e.g., arachnoid cyst).

Fibromyalgia Symptom Severity and Psychosocial Outcomes in Fibromyalgia Patients with Hypovitaminosis D: A Prospective Questionnaire Study.

OBJECTIVE: To evaluate the association between hypovitaminosis D and outcomes of symptom severity, mood disorders, fatigue, and quality of life in fibromyalgia (FM) patients. METHODS: Five hundred ninety-three FM patients were surveyed from May 2012 to November 2013. Patients with serum vitamin D <25 ng/mL were considered to have hypovitaminosis D. The primary outcome was FM symptom severity (FIQ-R questionnaire). Secondary outcomes included quality of life (SF-36), fatigue (MFI-20), anxiety (GAD-7), and depression (PHQ-9). Independent t tests and chi-square tests were performed for continuous and categorical variables, respectively. Regression analysis was performed adjusting for age, gender, body mass index, ethnicity, and season. A post hoc analysis examined for correlation between outcomes and serum vitamin D (ng/mL) as a continuous variable. RESULTS: One hundred twenty-two patients (20.6%) had hypovitaminosis D. In our adjusted regression analysis, the total FIQ-R score in patients with hypovitaminosis D was higher compared with control patients with adequate serum vitamin D (57.85 ± 18.09 vs 62.79 ± 18.10, P = 0.04). Adjusted regression analysis revealed higher total GAD-7 (P = 0.01) and higher total PHQ-9 scores (P = 0.04) in patients with hypovitaminosis D compared with control patients. There were no differences based on severity of depression or anxiety. No differences in fatigue or quality of life were identified. Unadjusted post hoc analysis revealed that as serum vitamin D increased, there was an association with lower total FIQ-R (ß coefficient = -0.11, P = 0.02) and lower SF-36 subscale scores of role-physical (ß coefficient = -0.10, P = 0.03). Adjusted post hoc analysis revealed no significant associations. CONCLUSIONS: Hypovitaminosis D may be a risk factor for worse symptom severity, anxiety, and depression in FM patients.

Tobacco Use in Fibromyalgia Is Associated With Cognitive Dysfunction: A Prospective Questionnaire Study.

OBJECTIVE: To evaluate the association between smoking and cognitive function in patients with fibromyalgia. PATIENTS AND METHODS: We surveyed 668 patients with fibromyalgia from May 1, 2012 through November 30, 2013 at a major tertiary referral center. Patients were categorized by smoking status. Primary outcome of interest was cognitive function (MASQ questionnaire), and secondary outcomes included fibromyalgia symptom severity (FIQ-R questionnaire), quality of life (SF-36 questionnaire), fatigue (MFI-20 questionnaire), sleep (MOS-sleep scale), anxiety (GAD-7 questionnaire), and depression (PHQ-9 questionnaire). Independent Students' t-tests and χ2 tests were performed for continuous and categorical variables, respectively. Univariate regression analysis identified variables predictive of outcomes, adjusting for age, gender, body mass index, marital status, and educational level. RESULTS: Ninety-four (14.07%) patients self-identified as smokers. There was an association of lower education level, unmarried status, and younger age in smokers compared with nonsmokers. In the adjusted univariate regression analysis, fibromyalgia smokers reported greater perceived total cognitive dysfunction (P=.009) and greater subscale scores of perceived difficulty in language (P=.03), verbal memory (P=.003), visual-spatial memory (P=.02), and attention (P=.04) compared with nonsmokers with fibromyalgia. For secondary outcomes, smokers with fibromyalgia reported greater severity of fibromyalgia-related symptoms (P=.006), worse quality-of-life index in the mental component scale (P=.02), greater sleep problems (P=.01), and increased anxiety (P=.001) compared with nonsmokers who had fibromyalgia. CONCLUSION: In patients with fibromyalgia, smoking is a risk factor for cognitive dysfunction. Moreover, smokers with fibromyalgia were more likely to report increased severity of fibromyalgia symptoms, worse quality of life, more sleep problems, and increased anxiety compared with nonsmokers with fibromyalgia.