Danielle Perret

Targeting voltage-gated calcium channels for neuropathic pain management.

SummaryVoltage-gated calcium channels (VGCC) play obligatory roles in diverse physiological functions. Pathological conditions leading to changes in their biophysical properties and expression levels may cause malfunctions of VGCC-mediated activities, resulting in disease states. It is believed that changes in VGCC properties under pain-inducing conditions may play a causal role in the development of chronic pain, including nerve injury-induced pain or neuropathic pain. For the past several decades, preclinical and clinical research in developing VGCC blockers or modulators for chronic pain management has been fruitful, leading to some U.S. Food and Drug Administration-approved drugs currently available for chronic pain management. However, their efficacy in pain relief is limited in some patients, and their long-term use is limited by their side-effect profiles. Certainly, there is room for improvement in developing more subtype-specific VGCC blockers or modulators for chronic pain conditions. In this review, we summarized the most recent preclinical and clinical studies related to chronic pain medications acting on the VGCC. We also included clinical trials aiming to expand the application of approved VGCC drugs to different pain states derived from various pathological conditions, as well as drug combination therapies trying to improve the efficacies and side-effect profiles of current pain medications.

Prediction of preoperative anxiety in children: who is most accurate?

BACKGROUND: In this investigation, we sought to assess the ability of pediatric attending anesthesiologists, resident anesthesiologists, and mothers to predict anxiety during induction of anesthesia in 2 to 16-yr-old children (n = 125). METHODS: Anesthesiologists and mothers provided predictions using a visual analog scale and children’s anxiety was assessed using a valid behavior observation tool the Modified Yale Preoperative Anxiety Scale. All mothers were present during anesthetic induction and no child received sedative premedication. Correlational analyses were conducted. RESULTS: A total of 125 children aged 2–16 yr, their mothers, and their attending pediatric anesthesiologists and resident anesthesiologists were studied. Correlational analyses revealed significant associations between attending predictions and child anxiety at induction (rs = 0.38, P < 0.001). Resident anesthesiologist and mother predictions were not significantly related to children’s anxiety during induction (rs = 0.01 and 0.001, respectively). In terms of accuracy of prediction, 47.2% of predictions made by attending anesthesiologists were within one standard deviation of the observed anxiety exhibited by the child, and 70.4% of predictions were within two standard deviations. CONCLUSIONS: We conclude that attending anesthesiologists who practice in pediatric settings are better than mothers in predicting the anxiety of children during induction of anesthesia. Although this finding has significant clinical implications, it is unclear if it can be extended to attending anesthesiologists whose practice is not mostly pediatric anesthesia.

Application of pulsed radiofrequency currents to rat dorsal root ganglia modulates nerve injury-induced tactile allodynia.

BACKGROUND: Application of pulsed radiofrequency (PRF) currents to the dorsal root ganglia (DRG) has been reported to produce relief from certain pain states without causing thermal ablation. In this study, we examined the direct correlation between PRF application to DRG associated with spinal nerve injury and reversal of injury-induced behavioral hypersensitivity in a rat neuropathic pain model. METHODS: Neuropathic lesioning was performed via left L5 spinal nerve ligation on male adult Sprague-Dawley rats. Once the injured rats had developed tactile allodynia, one group was then assigned to PRF treatment of the L5 DRG and another group was assigned to the sham treatment to the DRG. Behavioral testing was performed on both the control and treated paws using the von Frey filament test before the surgery and at indicated days. The resulting data were analyzed using a linear mixed model to assess the overall difference between the treatment groups and the overall difference among the study days. Cohens d statistic was computed from paired difference-from-baseline scores for each of the 14 study days after treatment and these measures of effect size were then used to descriptively compare the recovery patterns over time for each study group. RESULTS: Spinal nerve injury resulted in the development of behavioral hypersensitivity to von Frey filament stimulation (allodynia) in the hindpaw of the left (injury) side. Mixed linear modeling showed a significant difference between the treatment groups (P = 0.0079) and a significant change of paw withdrawal threshold means over time (P = 0.0006) for all 12 animals. Evaluation of Cohens d (effect size) revealed that the PRF-treated animals exhibited better recovery and recorded larger effect sizes than the sham-treated animals on 10 of the 14 post-PRF treatment days and exhibited moderate-to-strong effects posttreatment at days 8 to 10 and at and beyond day 32. CONCLUSIONS: Findings from this study support that PRF of the DRG causes reversal of nerve injury (spinal nerve ligation)-induced tactile allodynia in rats. This allodynia reversal indicates that nonablative PRF acting via modulation of the DRG can speed recovery in nerve injury–induced pain.

Hemispheric synchronized sounds and perioperative analgesic requirements.

BACKGROUND: Data on the effect of Hemisync® sounds on perioperative analgesic requirements are scant. METHODS: We randomized surgical outpatients into a treatment group that received Hemisync sounds (n = 20), a music group that received music (n = 20), and a control group that had a blank cassette tape (n = 20). All subjects underwent a controlled standardized propofol-nitrous-vecuronium and fentanyl general anesthesia. RESULTS: The treatment group had significantly reduced intraoperative fentanyl consumption (P < 0.05). Postoperatively, pain visual analog scale scores were significantly lower in the Hemisync group at 1 h (P = 0.02) and 24 h (P = 0.005). Subjects in the Hemisync group were also discharged earlier (P = 0.048). CONCLUSION: The use of Hemisync sounds before and during general anesthesia reduces intraoperative analgesic requirements, postoperative pain scores, and discharge time.

A Physician‐Driven Solution—The Association for Medical Ethics, The Physician Payment Sunshine Act, and Ethical Challenges in Pain Medicine

The practice of contemporary pain medicine is laced with a number of significant ethical challenges. Considerable difficulties include the overutilization of interventional procedures, the application of under-evidenced treatment modalities, and potentially superfluous opioid prescribing. As with many other fields in medicine, including orthopedic surgery, relationships with industry are both common and pervasive, and influence our medical practice through education, publications, and research. This article highlights these ethical challenges and broaches several physician-driven solutions: The Association for Medical Ethics, the Physicians Payment Sunshine inspired by it, and other non-legislative reforms are discussed.

Posterior knee pain

Posterior knee pain is a common patient complaint. There are broad differential diagnoses of posterior knee pain ranging from common causes such as injury to the musculotendinous structures to less common causes such as osteochondroma. A precise understanding of knee anatomy, the physical examination, and of the differential diagnosis is needed to accurately evaluate and treat posterior knee pain. This article provides a review of the anatomy and important aspects of the history and physical examination when evaluating posterior knee pain. It concludes by discussing the causes and management of posterior knee pain.

Exposure of the dorsal root ganglion to pulsed radiofrequency current in a neuropathic pain model of peripheral nerve injury.

The spinal nerve ligation model of neuropathic pain in rats, as originally described by Kim and Chung (Pain 50:355-363, 1992), provides an excellent venue to study the antinociception and modulation effects of pulsed radiofrequency (PRF) current in pain processing. We describe the procedure of application of PRF current near the exposed L5 dorsal root ganglion (DRG) in rats with L5 spinal nerve ligation injury-induced behavioral hypersensitivity. This method employs the direct visualization of the L5 DRG, allowing for confirmation of the location of the PRF probe adjacent to the DRG.

Improving Trainee Competency and Comfort Level with Needle Driving Using Simulation Training.

OBJECTIVE To assess whether a combination of lecture and model simulation improves resident competency and comfort level with needle driving for interventional pain medicine procedures. DESIGN Prospective, observational study. METHOD Trainees who rotated through the University of California, Irvine, outpatient pain medicine clinic were recruited for the study. Subjects were given a brief lecture and completed a survey with questions regarding their level of comfort with interventional pain medicine procedures. This was followed by a timed trial on a training simulator where the objective was to drive a needle to the target. After the trial, the subject was then given a 30-minute practice session with the simulation model. The subject was then asked to repeat the timed trial and complete a post-simulation survey. RESULTS All measures of the level of comfort increased significantly after subjects underwent the simulation training. In addition, subjects were able to significantly decrease their entrance time (P= 0.002), total time (P= 0.033), and vertical (P≤ 0.001) and horizontal deviation (P≤ 0.001) from the final target point after the simulation training. CONCLUSIONS Our study demonstrates that simulation training may improve both trainee comfort level and competency with needle driving. After a brief lecture and a 30-minute training session with the simulator, subjective comfort measures and competency measures (more subjects were able to reach the target, vertical and horizontal deviations from the target decreased) were significantly improved. This suggests that simulation may be a helpful tool in teaching needle driving skills.

A comprehensive, multispecialty approach to an acute exacerbation of chronic central pain in a tetraplegic.

Study design:We present a case report describing the multidisciplinary treatment of a tetraplegic spinal cord injury (SCI) patient who developed an acute exacerbation of chronic central pain.Objective:To bring further awareness to the importance of using a comprehensive, multidisciplinary approach in treating acute exacerbation of chronic central pain in SCI patients.Setting:University of California Irvine Medical Center, Orange, CA, USA.Case report:We present a 34-year-old man with a past medical history of C5 American Spinal Injury Association B tetraplegia secondary to a surfing accident 8 years prior, central pain syndrome, spasticity, autonomic dysreflexia and anxiety who arrived at the emergency room with a 1-month history of worsening acute on chronic pain refractory to opioid escalation. The multispecialty treatment plan included treatment of the patient’s urinary tract infection by the primary medicine service, management of the patient’s depression by the psychiatric service, treatment of bowel obstruction by general surgery and adjustment of pain medications by pain management. The patient was found to have stable neurological findings, neuroimaging unchanged from prior imaging and a urinary tract infection. Hospitalization was complicated by severe colonic dilation that required disimpaction by general surgery.Conclusion:The treatment of this patient’s acutely worsened central pain highlights the importance of applying a multidisciplinary approach to SCI patients with an acute exacerbation of chronic central pain. In this case, the multispecialty treatment plan included treatment of the patient’s urinary tract infection by the primary medicine service, management of the patient’s depression by the psychiatric service, treatment of bowel obstruction by general surgery, and adjustment of pain medications by pain management.

Diagnosis and Current Treatments for Sacroiliac Joint Dysfunction: A Review

The sacroiliac joint (SIJ) is a common pain generator for individuals with low back pain. Diagnosis and treatment of sacroiliac joint dysfunction is often a challenge due to the complex anatomy and biomechanics of the joint. In addition, patient presentation is often nonspecific. The purpose of this review article is to provide a concise overview of the relevant anatomy, pathogenesis, diagnosis, and the current conservative as well as interventional treatments for SIJ dysfunction.