Explantation Rates of High Frequency Spinal Cord Stimulation in Two Outpatient Clinics.

OBJECTIVES: To report the explantation rates of high frequency 10 kHz spinal cord stimulation (SCS) in a real-world setting. MATERIALS AND METHODS: This is a retrospective review of patients implanted with high frequency spinal cord stimulators over a 4-year period in two outpatient private practice clinics, from July 2015 through June 2019, using the Kaplan-Meier product-limit method to estimate probabilities of implant survival over time. RESULTS: The estimated median time to explantation was 3.5 years (95% confidence interval [CI] = 3.1-3.7) [Correction added on 15 October 2020, after first online publication: The preceeding sentence was amended to reflect the estimated median time.]. The estimated probabilities of implant survival beyond 1, 2, and 3 years postimplantation were 88.4% (95% CI = 81.3-93.0%), 76.5% (95% CI = 67.8-83.2%), and 60.7% (95% CI = 50.2-69.6%), respectively. The minimum (i.e., known) cumulative percentages of patients explanted by 1, 2, and 3 years postimplantation were 11.1% (14/126), 22.2% (28/126), and 32.5% (41/126), respectively. 65.9% of patients in this study had prior neurostimulation. CONCLUSIONS: Recently, high frequency SCS technology has been demonstrated as more effective in treatment of lower- and leg-pain, compared to conventional low frequency SCS, in a 12-month randomized controlled trial (SENZA-RCT). Longer term results have yet to be published. In this study, we found that the explantation rate was much higher than expected, based on the prior studies demonstrating its efficacy. As the use of neuromodulation continues to grow, longitudinal data will be critical in understanding its long-term effects on treated patients.

Healthcare professionals' knowledge, confidence and perceptions of pharmacogenomics in primary care and pain management.

Aim: To assess knowledge, confidence and perceptions of healthcare professionals specializing in primary care and pain management at Brigham and Women's Hospital, related to clinical pharmacogenomics (PGx). Methods: A 25-question online survey was distributed to 328 Brigham and Women's Hospital clinicians for analysis. Results: Thirty-four clinicians completed the survey. Respondents had minimal experience with PGx and limited awareness of PGx resources. Although respondents expressed belief that PGx has utility to improve medication-related patient outcomes, many lack confidence to apply PGx results to their practice. For clinical drug-gene questions relevant to primary care and/or pain management, respondents scored poorly. Conclusion: More clinician education is needed for appropriate utilization of PGx in clinical practice as it pertains to primary care and pain management.

Pain Neurology.

Pain is often the initial complaint for which patients seek medical care, presenting both a diagnostic and therapeutic challenge to the primary care provider. The appreciation of pain is not merely the result of abnormal sensory stimulation causing an unpleasant sensation but rather a combination of the recognition of the somatic discomfort in association with an emotional response to that discomfort. The perception of pain and the extent of distress and disability can vary depending on previous experience, cultural background, situational factors, and comorbid psychiatric disease. Though acute pain is usually the result of tissue damage, this is not always the case, as evidenced by primary headache disorders. Chronic pain may be the result of an injury, irreversible underlying disease, or clinical conditions such as fibromyalgia for which the mechanism remains unclear. Treatment of the underlying cause will usually effect a resolution or improvement in the pain, but when the discomfort persists, a consultation with a neurologist or pain management specialist should be considered.

Chronic estradiol replacement impairs performance on an operant delayed spatial alternation task in young, middle-aged, and old rats.

The current study examined effects of chronic estradiol replacement on a prefrontally-mediated working memory task at different ages in a rodent model. Ovariectomized young, middle-aged, and old Long-Evans rats were given 5% or 10% 17beta-estradiol in cholesterol vehicle via Silastic implants and tested on an operant delayed spatial alternation task (DSA). The two estradiol exposed groups did not perform as well as the vehicle control group did. Deficits were present at all but the longest delay, where all groups including the vehicle control group performed poorly. Surprisingly, there was not a significant effect of age or an age by estradiol interaction, despite the fact that old rats had longer latencies to respond after both correct and incorrect lever presses. These data confirm our earlier finding that chronic estradiol treatment has an impairing effect on working memory as measured on DSA task. However, contrary to expectations, young, middle-aged and old rats were similarly impaired by chronic estradiol treatment; there were no indications of differential effects at different periods of the lifespan. Also contrary to expectations, there were no indications of a decline in DSA performance with advancing age. Overall, the results demonstrate that chronic estradiol exposure causes deficits in the DSA performance of ovariectomized female rats, not only in young adulthood, but also at older ages analogous to those at which hormone replacement therapy is commonly prescribed in humans.

Effects of chronic estradiol treatment on delayed spatial alternation and differential reinforcement of low rates of responding.

Estrogens have been shown to both enhance and impair cognitive function depending on several factors, including regimen of hormone treatment, age of subject, and task attributes. In rodent models, estradiol tends to enhance spatial learning and impair response or cued learning, but effects on executive functions are less well-studied. In this experiment, spatial working memory and response inhibition were tested using delayed spatial alternation (DSA) and differential reinforcement of low rates of responding (DRL) tasks in ovariectomized rats that were given chronic estradiol via Silastic implants resulting in serum estradiol concentrations of 86.2 +/- 8.2 (SEM) pg/ml. Rats were tested for 25 days DSA with variable delays of 0, 3, 6, 9, and 18 seconds between lever presentations, followed by 30 days on a DRL-15s operant schedule. Estradiol-replaced rats showed a significantly lower proportion of correct responses on the DSA task compared to vehicle-implanted ovariectomized animals. On DRL, estradiol-treated rats showed a lower ratio of reinforced to nonreinforced presses. These data suggest that chronic estrogen exposure may impair rats' abilities on measures of executive function including working memory and response inhibition.

A Prospective, Randomized, Double-Blind, Placebo-Controlled Trial to Evaluate Intravenous Acetaminophen Versus Placebo in Patients Undergoing Robotic-Assisted Laparoscopic Prostatectomy.

Radical prostatectomy for prostate cancer is one of the most commonly performed operations in men. The objective of this study was to determine the impact of intravenous (IV) acetaminophen when added to the perioperative analgesic regimen for robotic-assisted laparoscopic prostatectomy (RALP) on hospital length of stay (LOS), postoperative pain scores, and opioid consumption. In this prospective, randomized, double-blind, placebo-controlled trial, a total of 86 patients undergoing RALP were prospectively enrolled and randomly assigned to receive either 1 g IV acetaminophen (study group; n = 43) or IV placebo (n = 43) within 15 minutes following the induction of anesthesia and prior to surgical incision. Seventy-five records were completed and included for analysis. Pain scores were recorded every 30 minutes for 2 hours in the postanesthesia care unit (PACU) and then 16 distinct time points for 48 hours after PACU discharge. Repeat doses of IV acetaminophen or placebo was given every 6 hours for a total of four doses. Median average pain scores after PACU discharge between the treatment and placebo groups were 0.62 vs. 0.88, respectively (P = .055), over the first 24 hours and 1.28 vs. 2.25, respectively (P = .13), over the second 24 hours. Hospital LOS was shorter in the IV acetaminophen group compared with placebo by 32% (P = .006). Median intraoperative opioid use in the IV acetaminophen group was 42 mg morphine equivalents compared with 50 mg in placebo (P = .64) and 8 mg in both groups postoperatively (P = .16). Overall, use of perioperative IV acetaminophen decreased hospital LOS without a significant difference in PACU LOS, pain scores, or opioid use.

Alterations in DRH and DRL performance in rats developmentally exposed to an environmental PCB mixture.

Schedule-controlled responding was examined in offspring of rats exposed to a PCB mixture formulated to mimic the PCB congener profile in fish from the Fox River in Green Bay, WI. Female rats were administered 0, 1, 3, or 6 mg/kg/day of the PCB mixture beginning four weeks prior to breeding until weaning on postnatal day 21. When offspring were approximately 235 days old, they were tested on three different schedules of a differential reinforcement of high rate (DRH) operant task (DRH 2:1, DRH 4:2, and DRH 8:4). DRH testing was followed by testing on the differential reinforcement of low rate (DRL) operant task in which rats had to inhibit responding until 15 s had elapsed (DRL 15) from the previous response in order to obtain a food reinforcer. After completion of DRL 15 testing, 3 days of extinction testing were conducted (DRL EXT) during which no reinforcers were delivered. Developmental exposure to the higher PCB doses resulted in shorter inter-response times (IRTs) and shorter response durations during DRH 8:4, which translated into a greater percentage of reinforced trials. For DRL 15, no significant exposure-related effects were observed on the number of responses or reinforcers earned, or the number or proportion of responses with long or short inter-response times during acquisition or steady state performance. However, during DRL EXT, rats developmentally exposed to the highest PCB dose responded more than controls, produced significantly more short IRT responses, and had a significantly lower proportion of long IRT responses. Overall, exposure to this PCB mixture resulted in increased responding which was suggestive of a deficit in inhibitory control.

Purkinje cell and cerebellar effects following developmental exposure to PCBs and/or MeHg.

We recently reported that rats exposed to PCBs and MeHg during development were impaired on the rotating rod, a test of balance and coordination that is often indicative of cerebellar damage. In addition, developmental PCB exposure is known to dramatically reduce circulating thyroid hormone concentrations, which may have a negative impact on cerebellar development. Therefore, we investigated the effects of combined PCB and MeHg exposure on Purkinje cells and the cerebellum. The serum and brains from littermates of the animals tested on the rotating rod were collected at weaning, and we also collected brains from the adult animals at the end of motor testing. Four groups were studied: 1) vehicle controls, 2) PCBs only (Aroclor 1254, 6 mg/kg/d, oral), 3) MeHg only (0.5 ppm, in dams' drinking water), and 4) PCB+MeHg (at the same doses as in individual toxicant exposures). Female Long-Evans rats were exposed beginning 4 weeks prior to breeding with an unexposed male and continuing until postnatal day (PND) 16. There was a significant reduction in serum T4 and T3 concentrations in the PCB and PCB+MeHg pups on PND21. Golgi-impregnated Purkinje cells were examined in PND21 brains, but there were no significant exposure-related effects on primary dendrite length, branching area, or structural abnormalities. However, all three male exposure groups had a marginally significant increase in Purkinje cell height, which may suggest a subtle thyromimetic effect in the cerebellum. Cresyl-violet stained sections from the adult brains showed no exposure-related effects within paramedian lobule in Purkinje cell number, total lobule volume or layer volumes (molecular, granule cell and white matter layers). Evidence is provided for the dysregulation of expression of cerebellar ryanodine receptor (RyR) isoforms in PCB-exposed brains, and this could contribute to the rotating rod deficit by changing critical aspects of intracellular calcium signaling within the cerebellum.

Motor impairment in rats exposed to PCBs and methylmercury during early development.

Epidemiological and laboratory studies indicate that polychlorinated biphenyls (PCBs) and methyl mercury (MeHg) may have additive or interactive adverse effects on nervous system function. Prior studies have shown that high doses of MeHg target the cerebellum and impair balance and coordination, but the effects of PCBs on cerebellar function were unknown. In addition, the combined effects of PCBs and MeHg on cerebellar function have not been studied previously. Therefore, we investigated the effects of developmental exposure to PCBs, MeHg, or PCBs + MeHg on three motor tasks that involve cerebellar functions. Female Long-Evans rats were exposed to MeHg (0.5 ppm in drinking water), PCBs (6-mg/kg/d Aroclor 1254), PCBs + MeHg, or vehicle only beginning 4 weeks prior to breeding, through pregnancy, and continuing through postnatal day (PND) 16. Starting at approximately PND 60, one male and one female from each litter were tested on three motor tasks that involve cerebellar function. PCB + MeHg-exposed rats were impaired relative to the controls on a task requiring them to traverse a rotating rod. Rats exposed to PCBs alone were also somewhat impaired relative to the controls, whereas MeHg-exposed rats were not significantly different from the controls. There were no statistically significant deficits related to PCB or MeHg exposure on a vertical rope-climbing test or a parallel bar test. Our results demonstrate that the possibility of additive neurotoxic effects of PCBs and MeHg needs to be seriously considered.

Genistein administered as a once-daily oral supplement had no beneficial effect on the tibia in rat models for postmenopausal bone loss.

OBJECTIVE: Estrogen deficiency after menopause results in rapid bone loss, predisposing women to osteoporotic fractures. Genistein, a phytoestrogen present in high concentrations in soy, is an ingredient in dietary supplements aggressively marketed for bone health. However, in a recent long-duration clinical trial in postmenopausal women, the efficacy of soy extracts in reducing bone loss was disappointing. To better understand the failure of soy extracts to consistently induce a robust skeletal response in women, we investigated the long-term (5 mo) efficacy of genistein, administered as a daily oral supplement, (1) in preventing cancellous bone loss in skeletally mature virgin Long-Evans rats ovariectomized at 7 months of age and (2) in improving cancellous bone mass and architecture in aged retired-breeder rats ovariectomized at 16 or 22 months of age. METHODS: Rats within each age group were randomly assigned into one of three treatment groups (n = 7-12 rats/group): (1) vehicle control, (2) genistein 485 µg/day, or (3) genistein 970 µg/day, resulting in mean (SE) serum genistein levels of 0.18 (0.10), 0.76 (0.15), and 1.48 (0.31) µM, respectively. Total tibia bone mass and density were evaluated using dual-energy x-ray absorptiometry, whereas cancellous bone mass and architecture in the tibial metaphysis, as well as cortical bone mass and architecture in the tibial diaphysis, were evaluated by micro-CT. RESULTS: Oral genistein administered as a dietary supplement did not influence the cumulative effects of ovariectomy, aging, and/or reproductive history on cancellous and cortical bone mass and architecture. CONCLUSIONS: Serum levels of genistein similar to those in women consuming a high-soy diet are ineffective in preventing or treating bone loss in rat models for postmenopausal osteoporosis.

Intravenous iron given prior to pregnancy for restless legs syndrome is associated with remission of symptoms.

Restless legs syndrome (RLS) is more common during pregnancy than in the general population, occurring at a 2-3 times higher prevalence. While iron, genetics, and central nervous system dopamine have been shown to play major roles in RLS unrelated to pregnancy, the etiology and treatment of RLS during pregnancy have not been adequately delineated. We describe a novel approach where a 23-year-old female was given intravenous iron prior to pregnancy, with complete remission of RLS symptoms until five months postpartum. Factors other than iron status that may have influenced the course of remission and relapse were oral contraceptive use, antidepressant use, and a strong family history of RLS.

A systematic evaluation of thoracic interlaminar epidural injections.

BACKGROUND: There is a paucity of literature on the use of epidural injections for the treatment of chronic mid and upper back pain due to disc herniation and radiculitis, axial or discogenic pain, spinal stenosis, post surgery syndrome, and post thoracotomy pain syndrome. STUDY DESIGN: A systematic review of therapeutic thoracic epidural injection therapy for chronic mid and upper back pain. OBJECTIVE: The objective of this systematic review is to determine the effects of thoracic interlaminar epidural injections with or without steroids, with or without fluoroscopy, and for various conditions including disc herniation and radiculitis, axial or discogenic pain, spinal stenosis, post thoracic surgery syndrome, and post thoracotomy pain syndrome. METHODS: The available literature on thoracic interlaminar epidural injections with or without steroids in managing various types of chronic mid and upper back pain was reviewed. The quality assessment and clinical relevance criteria utilized were the Cochrane Musculoskeletal Review Group criteria as utilized for interventional techniques for randomized trials and the criteria developed by the Newcastle-Ottawa Scale criteria for observational studies. The level of evidence was classified as good, fair, or limited (or poor) based on the quality of evidence developed by the U.S. Preventive Services Task Force (USPSTF). Data sources included relevant literature identified through searches of PubMed and EMBASE from 1966 to March 2012, and manual searches of the bibliographies of known primary and review articles. OUTCOME MEASURES: The primary outcome measure was pain relief (short-term relief = up to 6 months and long-term > 6 months). Secondary outcome measures were improvement in functional status, psychological status, return to work, and reduction in opioid intake. RESULTS: For this review, 17 studies were identified, including studies examining adverse reactions. Only 2 studies were included: one randomized trial and one non-randomized or observational study. The results of this systematic review evaluating the effectiveness of thoracic epidural injections with or without steroids in managing chronic thoracic pain shows fair evidence with one randomized trial in patients with various causes; whereas the evidence is limited based on one non-randomized study evaluating chronic pain in post thoracotomy syndrome. LIMITATIONS: The limitations of this study include paucity of evidence. CONCLUSION: The evidence based on this systematic review for thoracic epidural injection in treating chronic thoracic pain is considered fair and limited for post thoracotomy pain.

Pharmacology of opioids in the treatment of chronic pain syndromes.

The perpetual pursuit of pain elimination has been constant throughout human history and pervades human cultures. In some ways it is as old as medicine itself. Cultures throughout history have practiced the art of pain management through remedies such as oral ingestion of herbs or techniques believed to have special properties. In fact, even Hippocrates wrote about the practice of trepanation, the cutting of holes in the body to release pain. Current therapies for management of pain include the pervasive utilization of opioids, which have an extensive history, spanning centuries. There is general agreement about the appropriateness of opioids for the treatment of acute and cancer pain, but the long-term use of these drugs for treatment of chronic non-malignant pain remains controversial. The pros and cons regarding these issues are beyond the scope of this review. Instead, the purpose of this review will be directed towards the pharmacology of commonly prescribed opioids in the treatment of various chronic pain syndromes. Opium, derived from the Greek word for "juice," is extracted from the latex sap of the opium poppy (Papaverum somniferum). The juice of the poppy is the source of some 20 different alkaloids of opium. These alkaloids of opioids can be divided into 2 chemical classes: phenanthrenes (morphine, codeine, and thebaine) and benzylisoquinolines (agents that do not interact with opioid receptors).

Estradiol impairs response inhibition in young and middle-aged, but not old rats.

Estrogens have been shown to have a strong influence on such cognitive domains as spatial memory, response learning, and several tasks of executive function, including both working memory and attention. However, the effects of estrogens on inhibitory control and timing behavior, both important aspects of executive function, have received relatively little attention. We examined the effects of estradiol on inhibitory control and timing behavior using a differential reinforcement of low rates of responding (DRL) task. Ovariectomized young (3 month), middle-aged (12 month), and old (18 month) Long-Evans rats were implanted with Silastic implants containing 0, 5 or 10% 17ß-estradiol in cholesterol vehicle and were tested on a DRL task requiring them to wait 15s between lever presses to receive a food reinforcer. The ratio of reinforced to non-reinforced lever presses did not differ across age in the cholesterol vehicle group. Conversely, 17ß-estradiol impaired learning of the DRL task in young and middle-aged rats, but the learning of old rats was not impaired relative to vehicle controls following either 5% or 10% 17ß-estradiol treatment. Overall, old rats also made fewer lever presses than both the young and middle-aged rats. These results provide new evidence that estrogens impair inhibitory control, an important aspect of self regulation, and add to existing evidence that estrogens differentially affect cognition at different ages.

Impact of dietary genistein and aging on executive function in rats.

Genistein is an estrogenic soy isoflavone widely promoted for healthy aging, but its effects on cognitive function are not well-understood. We examined the cognitive effects of once daily oral genistein treatment at two doses (approximately 162 microg/kg/day low dose and a 323 microg/kg/day high dose) in ovariectomized young (7 month), middle-aged (16 month), and old (22 month) Long-Evans rats. Operant tasks including delayed spatial alternation (DSA), differential reinforcement of low rates of responding (DRL), and reversal learning that tap prefrontal cortical function were used to assess working memory, inhibitory control/timing, and strategy shifting, respectively. At the conclusion of cognitive testing, brains were collected and relative densities of D1 and D2 dopamine receptors and dopamine transporter (DAT) were measured in the prefrontal cortex. On the DSA task, the high dose old group performed worse than both the high dose young and middle-aged groups. On the DRL task, the high dose of genistein resulted in a marginally significant impairment in the ratio of reinforced to non-reinforced lever presses. This effect was present across age groups. Age effects were also found as old rats performed more poorly than the young and middle-aged rats on the DSA overall. In contrast, middle-aged and old rats made fewer lever presses on the DRL than did the young rats, a pattern of behavior associated with better performance on this task. Moreover, while DAT levels overall decreased with age, genistein treatment produced an increase in DAT expression in old rats relative to similarly aged control rats. D1 and D2 densities did not differ between genistein dose groups or by age. These results highlight the fact that aspects of executive function are differentially sensitive to both genistein exposure and aging and suggest that altered prefrontal dopamine function could potentially play a role in mediating these effects.

Developmental exposure to PCBs and/or MeHg: effects on a differential reinforcement of low rates (DRL) operant task before and after amphetamine drug challenge.

The current study assessed the effects of developmental PCB and/or MeHg exposure on an operant task of timing and inhibitory control and determined if amphetamine (AMPH) drug challenges differentially affected performance. Long-Evans rats were exposed to corn oil (control), PCBs alone (1 or 3 mg/kg), MeHg alone (1.5 or 4.5 ppm), the low combination (1 mg/kg PCBs+1.5 ppm MeHg), or the high combination (3 mg/kg PCBs+4.5 ppm MeHg) throughout gestation and lactation. An environmentally relevant, formulated PCB mixture was used. Male and female offspring were trained to asymptotic performance on a differential reinforcement of low rates (DRL) operant task as adults. PCB-exposed groups had a lower ratio of reinforced to non-reinforced responses than controls. Groups exposed to MeHg alone were not impaired and the deficits observed in PCB-exposed groups were not seen when PCBs were co-administered with MeHg. AMPH was less disruptive to responding in males receiving PCBs alone, MeHg alone, and 1.0 mg/kg PCB+1.5 ppm MeHg. Paradoxically, the disruption in responding by AMPH in males given 3.0 mg/kg PCB+4.5 ppm MeHg did not differ from controls. Exposed females from all treatment groups did not differ from controls in their AMPH response. Overall, the findings suggest that developmental exposure to PCBs can decrease DRL performance. Co-exposure to MeHg seemed to mitigate the detrimental effects of PCBs on performance. The finding that the disruptive effects of AMPH on DRL performance were lessened in some groups of exposed males suggests that alterations in dopaminergic functioning may have a role in behavioral changes seen after perinatal PCB and MeHg exposure.