Peripheral Nerve Stimulation Uses High-Frequency Electromagnetic Technology to Power an Implanted Neurostimulator with a Separate Receiver for the Treatment of Chronic Pain in the Lower Extremities.

BACKGROUND: Lower extremity pain is one of the most common types of chronic pain and can be very challenging to treat using conservative management modalities. OBJECTIVES: Our study intends to present the effective management of chronic neuralgias in the lower extremities through peripheral nerve stimulation (PNS). SETTING: This retrospective study included 21 patients who received a permanent Curonix Freedom® PNS System for treating chronic pain in the lower extremities. A retrospective chart review was conducted to assess the baseline and follow-up parameters. METHODS: Fourteen of the patients (67%) received one neurostimulator at either the superficial peroneal or posterior tibial nerve. Seven patients (33%) received 2 neurostimulators at either the sural and superficial peroneal, posterior tibial and superficial peroneal, or common and superficial peroneal nerves. The data were collected from electronic medical records, followed by case report forms. Pain scores and complications were reported up to 6 months after permanent implantation. Adverse events (AEs) were reported descriptively and classified as serious or nonserious AEs and related or nonrelated AEs. RESULTS: At the end of the trial visit, 21 of the 21 patients (100%) reported more than 50% pain relief, with mean pain scores reducing from 7.29 ± 0.9 to 2.81 ± 0.7 (61%; P < 0.001). Nineteen patients completed the long-term follow-up. Fourteen of those 19 patients (74%) experienced at least a 50% improvement in pain. The average NRS score decreased significantly to 3.66 ± 1.8 (50%; P < 0.001). No complications were reported. CONCLUSION: PNS done with the Curonix Freedom® PNS System is an effective and safe therapy for lower-extremity neuralgias.

The effectiveness of repeat celiac plexus neurolysis for pancreatic cancer: a pilot study.

BACKGROUND: Celiac plexus neurolysis (CPN) is an effective but temporary management tool for pancreatic cancer pain (PCP). Clinical studies have shown the duration of benefit with initial CPN to be apaproximately 3 months. When pain recurs, CPN may be repeated, but the outcomes for repeat CPN are not well established. The objective of this study is to determine the success rate and duration of relief following repeat celiac plexus neurolysis (rCPN) for PCP. METHODS: Patients who underwent rCPN were identified from a database and their records reviewed. Responses of rCPN were then compared with iCPN for success rates and duration of relief. Success was defined as ≥ 50% pain relief lasting ≥ 1 month. RESULTS: Overall, there were 24 rCPN performed. The success rate decreased from 67% after initial CPN to 29% following rCPN (P = 0.13). The mean duration of pain relief decreased in parallel from 3.4 months (iCPN) to 1.6 months (rCPN) (P = 0.03). Among those who had a successful rCPN, 2.9 months elapsed from iCPN to rCPN, with disease progression noted in 29%. In those who failed rCPN, 7.8 months elapsed, with disease progression apapreciated in 71% of cases. CONCLUSIONS: rCPN does not provide as much pain relief as iCPN. Disease progression as detailed on imaging appears to be a major factor in the limitations of rCPN. Further prospective studies are warranted to confirm these results and investigate the utility of rCPN.

Spinal cord stimulation in the treatment of cancer-related pain: "back to the origins".

Spinal cord stimulation (SCS) has been used in the treatment of chronic pain for more than 40 years. The most common indication for SCS in the USA is failed back surgery syndrome (FBSS). Interestingly, the first two spinal cord stimulators ever implanted were in patients suffering from bronchogenic carcinoma and pelvic cancer, respectively. While cancer accounts for millions of deaths each year in the USA, pain is often the first sign of malignancy. An increasing number of people suffer from cancer-related pain each year and many receive suboptimal relief. Given the demonstrated value of spinal cord stimulation in the treatment of neuropathic pain, spinal cord stimulation should be considered "earlier" as an adjunct to the treatment of cancer-related pain. In addition, with the improving survival rates associated with advances in cancer treatment, spinal cord stimulation may help reduce the risk of development of chronic neuropathic pain in survivors.

Updated perspectives on occipital nerve stimulator lead migration: case report and literature review.

OBJECTIVES: Patients with occipital neuralgia are often refractory to or intolerant of standard pharmacological and interventional management strategies. Although occipital nerve stimulation (ONS) may provide a unique alternative for such cases, a steep technical learning curve still exists. Lead migration (LM) is among the most challenging issues facing implanters performing ONS implantation. We present an unusual case of LM after ONS implantation and discuss technical aspects for successful revision. METHODS: A retrospective review of medical records and fluoroscopic images was conducted to provide a case report of ONS LM and revision. A PubMed online search for the keywords occipital, stimulation, migration, and revision was also performed for literature review. CASE REPORT: A 35-year-old man with refractory occipital neuralgia had loss of greater occipital nerve paresthesia coverage and worsened occipital headaches 11 months after ONS implantation using a midline approach. Fluoroscopic imaging confirmed lateral LM. Although most LMs occur in the lateral-to-medial trajectory, this case was unique in that LM occurred from a medial-to-lateral trajectory despite using current standard safeguards. DISCUSSION: In an era in which reducing health care expenditures is becoming increasingly important, current complication rates could curtail future acceptance and utilization of ONS. This fact and our case report underscore the importance of a continued drive toward technical advances and a reduction in complications associated with this important treatment modality. Further prospective investigation into the mechanism of action, mechanism of complications, optimization of surgical techniques, and long-term efficacy is warranted.

Cephalad lead migration following spinal cord stimulation implantation.

Lead migration (LM) is the most common complication after spinal cord stimulation (SCS). Although multiple reports of caudad LM have been described, cephalad LM has not been reported. Here we describe a case in which a stimulator lead migrates in the cephalad direction. A 60-year-old male with failed back surgery syndrome underwent SCS lead implantation via a dual lead approach to the top of vertebral body (VB) T9. A standard strain relief loop was used for each lead in the paramedian pocket. Postoperative testing revealed 100% paresthesia coverage of the painful areas. For the first 4 days, the patient continued to have excellent coverage; however, by the seventh day, the paresthesias ascended to above the nipple line. At the 2-week follow-up, cephalad migration of the left lead to the top of VB T1 was confirmed on fluoroscopy. The patient underwent successful lead revision in which a single paramedian incision technique was used to place extra sutures and a "figure-of-eight" strain relief loop. We provide the first case report of significant cephalad LM following SCS lead implantation. This migration can occur despite the use of current standard anchoring techniques. Additional investigation into the mechanism of such LM and lead-securing techniques is warranted.

Contemporary insights into painful diabetic neuropathy and treatment with spinal cord stimulation.

A substantial body of literature is available on the natural history of diabetes, but much less is understood of the natural history of painful diabetic peripheral neuropathy (PDPN), a pervasive and costly complication of diabetes mellitus. Multiple mechanisms have been proposed, including polyol pathway activation, advanced glycosylation end-product formation, and vasculopathic changes. Nevertheless, specific treatment modalities addressing these basic issues are still lacking. The mainstay of treatment includes pharmacological management with antidepressants, anticonvulsants, and opioids, but these drugs are often limited by unfavorable side-effect profiles. For over 30 years, spinal cord stimulation (SCS) has been used extensively for the management of various chronic neuropathic pain states. In the past decade, interest in the use of SCS for treatment of PDPN has increased. This article reviews pathophysiological mechanisms of PDPN, proposed mechanisms of SCS, and the role of SCS for the treatment of PDPN.

Preventing Chronic Pain following Acute Pain: Risk Factors, Preventive Strategies, and their Efficacy.

Chronic pain is the leading cause of disability in the United States. The transition from acute to persistent pain is thought to arise from maladaptive neuroplastic mechanisms involving three intertwined processes, peripheral sensitization, central sensitization, and descending modulation. Strategies aimed at preventing persistent pain may target such processes. Models for studying preventive strategies include persistent post-surgical pain (PPP), persistent post-trauma pain (PTP) and post-herpetic neuralgia (PHN). Such entities allow a more defined acute onset of tissue injury after which study of the long-term effects is more easily examined. In this review, we examine the pathophysiology, epidemiology, risk factors, and treatment strategies for the prevention of chronic pain using these models. Both pharmacological and interventional approaches are described, as well as a discussion of preventive strategies on the horizon.

Lumbar transforaminal epidural dexamethasone: a prospective, randomized, double-blind, dose-response trial.

BACKGROUND AND OBJECTIVES: Serious adverse events related to particulate steroids have curtailed the use of transforaminal epidural steroid injections for radicular pain. Dexamethasone has been proposed as an alternative. We investigated the efficacy, dose-response profile, and safety of 3 doses of epidural dexamethasone. METHODS: A prospective, randomized, double-blind, dose-ranging design was used. A total of 98 subjects were randomized to transforaminal epidural dexamethasone 4 mg (n = 33), 8 mg (n = 33), or 12 mg (n = 32). The primary outcome measure for this study was reduction in radicular pain according to the visual analog scale from baseline, with 30% reduction or higher considered clinically meaningful. Secondary measures included the Oswestry Low Back Disability Scale, Subject Global Impression of Change, Subject Global Satisfaction Scale, and adverse events. Outcomes were assessed at 1, 4, 8, and 12 weeks after injection. Outcome measures, sample size, and statistical analysis were defined before enrollment. RESULTS: Mean radicular pain according to the visual analog scale compared with baseline was reduced 41.7%, 33.5%, and 26.6% at 4, 8, and 12 weeks, respectively, after injection. Oswestry disability ratings declined from "moderate" at baseline to "minimal" at 4, 8, and 12 weeks after injection. There was no statistical difference between groups for either measure (all P values < 0.05, Bonferroni-corrected). Parallel effects were observed in "impression of change" and "satisfaction" measures. No serious adverse events were noted. CONCLUSIONS: Transforaminal epidural dexamethasone provides statistically significant and clinically meaningful improvement in radicular pain at 12 weeks after injection, with parallel improvements in disability, impression of change, and satisfaction measures. There was no difference in efficacy for dexamethasone 4 mg compared with 8 or 12 mg. The optimal dose of epidural dexamethasone may be lower than 4 mg, further increasing the long-term safety and tolerability of this treatment. Current data are reassuring with regard to the safety of dexamethasone for transforaminal epidural steroid injection.

Updated perspectives on neurogenic thoracic outlet syndrome.

Pain represents a foremost feature of neurogenic thoracic outlet syndrome (NTOS). Similar to other persistent pain conditions, the physical discomfort associated with NTOS can cause severe and often debilitating symptoms. In fact, those suffering from the syndrome report a quality of life impacted as significantly as those with chronic heart failure. This evidence-based literature review focuses on the classification, etiology, clinical presentation, diagnostic measures, and surgical treatment of NTOS, with a focus on nonoperative therapies such as physical modalities, pharmacological therapies, and more contemporary minimally invasive intramuscular treatments with botulinum toxin.

Nutritional problems in end-stage liver disease: contribution of impaired gastric emptying and ascites.

GOALS: To evaluate gastric emptying before and after paracentesis in patients with cirrhosis. BACKGROUND: Patients with ascites often report early satiety. The effect of paracentesis on gastric emptying has not been studied previously. STUDY: Twelve patients who required therapeutic paracentesis were studied (mean age, 57 years; range, 47-69 years). Gastric emptying was performed with radionuclide scintigraphy. Satiety was evaluated with a visual analogue scale. Wilcoxon signed-rank tests were used for comparison between pre-and poststudies. RESULTS: The causes of cirrhosis included alcohol (seven patients), a combination of alcohol and hepatitis C (two), chronic hepatitis C only (one), primary biliary cirrhosis (one), and cryptogenic (one). The median volume of ascitic fluid removed at paracentesis was 5,450 mL (range, 2,500-7,200 mL). Median 2-hour gastric emptying was 65.5% before paracentesis and 61.5% after ( p > 0.05). Median 4-hour gastric emptying was 92.5% before paracentesis and 96.5% after ( p > 0.05). Both satiety score and caloric intake were significantly improved after paracentesis ( p < 0.05). CONCLUSIONS: Although satiety and calorie intake improve after large-volume paracentesis in patients with cirrhosis, these changes do not seem to correspond with improved gastric emptying. Therefore, other mechanisms most likely contribute to satiety.