Contemporary management of neuropathic pain for the primary care physician

Benzazepinone Nav1.7 blockers: potential treatments for neuropathic pain

A series of benzazepinones were synthesized and evaluated as hNa(v)1.7 sodium channel blockers. Several compounds from this series displayed good oral bioavailability and exposure and were efficacious in a rat model of neuropathic pain.

Epidemiology, Public Health Burden, and Treatment of Diabetic Peripheral Neuropathic Pain: A Review

OBJECTIVE

The literature examining the epidemiology, quality of life burden, cost, and treatment of diabetic peripheral neuropathy pain (DPNP) in U.S. adults was reviewed.

DESIGN

A comprehensive computerized literature review of DPNP was conducted using MEDLINE and other databases, which were searched from 1995 through August 2004 using the Medical Subject Headings diabetic neuropathies and pain combined with relevant terms. A supplementary MEDLINE search of clinical trials of pharmacological treatments for DPNP was conducted through July 2005.

RESULTS

The search resulted in 321 articles. Several epidemiological studies assessed diabetic peripheral neuropathy among patients with diabetes and reported prevalence rates of 26-47%. No estimates of DPNP prevalence were reported, although one study (N = 2,405) reported that 26.8% of participants with diabetes experienced either pain or tingling. Randomized clinical trials have been conducted of several medications and classes of medication in patients with DPNP, and the U.S. Food and Drug Administration has approved two drugs for DPNP. Several published studies reported that DPNP impairs quality of life. Estimates of the costs of DPNP in the United States were limited. One study estimated average annual pain medication costs of $1,004 per DPNP patient.

CONCLUSIONS

This review of DPNP identifies gaps in the literature and highlights the need for further study. The establishment of a consistent definition and diagnostic code for DPNP would improve ability to collect data and understand the impact of DPNP on patients and the health care system. Well-designed, prospective studies are needed to better define the epidemiology and public health burden of DPNP.

Subcutaneous peripheral injection of cationized gelatin/DNA polyplexes as a platform for non-viral gene transfer to sensory neurons

Selective modulation of sensory neuron gene expression could have numerous applications for the peripheral nervous system. Here, we report that subcutaneous peripheral injection of plasmid DNA complexed with a non-viral cationized gelatin (CG) vector led to transgene expression in rat lumbar dorsal root ganglia (DRGs). CG/DNA polyplexes appeared to undergo rapid retrograde transport through sciatic and spinal nerves, with reporter gene messenger RNA (mRNA) expression detectable in L4 and L5 DRGs within 60 hours. Maximum transgene expression was observed for polyplexes formed at 7.5:1 CG-to-DNA weight ratio under salt-free conditions, which generated 615 +/- 112 nm nanoparticles with zeta-potential of 9.4 +/- 0.19 mV. Six days after injection of the CG/DNA polypex, reporter gene protein immunofluorescence was observed in 1,164 +/- 176 DRG neurons, representing an estimated transfection rate of 47% of targeted neurons. Reporter gene expression was not detected in heart, lung, or liver tissues, suggesting a lack of systemic uptake. Measurements of tactile sensitivity indicate that CG/DNA injection did not cause behavioral toxicity. The injection platform was further used for plasmid-driven short hairpin RNA-mediated suppression of glyceraldehyde-3-phosphate dehydrogenase. This non-invasive gene delivery system could be used for the mechanistic study and targeted molecular evaluation of peripheral nervous system pathologies such as neuropathic pain.

Therapieoptionen der schmerzhaften diabetischen Polyneuropathie

Distal symmetrical polyneuropathy is the most frequent manifestation of diabetic neuropathy and crucially contributes to the development of diabetic foot and subsequent amputation in 70 to 80% of all cases. In 10 to 15% of affected patients considerable pain is present, in particular in early diabetic polyneuropathy. This review summarizes evidence based data on prevention, neuroregenerative, and symptomatic treatment of painful diabetic polyneuropathy. The most important clinical trials on treatment and prevention are presented. Conclusions from these clinical studies in particular detailed treatment recommendations including dosage and side effects are given. Combined treatments and escalating therapies for severe pain syndromes are discussed.

Neuropathic pain in soft tissue complaints

Many soft tissue complaints are associated with the development of neuropathic pain. This pain is produced by pathophysiological processes that are different to the processes involved in the generation of the inflammatory or nociceptive pain more commonly encountered in soft tissue disorders. One of the consequences of this is that neuropathic pain can often be less responsive to standard analgesic therapies. The use of alternative analgesic strategies may be necessary if we are to treat neuropathic pain successfully. This chapter aims to outline some of the clinical features associated with neuropathic pain, the aetiological factors leading to its development and the evidence base (or lack) behind current treatment strategies. It will try to provide a rational approach to the management of neuropathic pain in patients with soft tissue disorders, particularly focusing on pharmacological management. Neuropathic pain is the focus of much current research activity, particularly pharmacological research, and this chapter will attempt to identify gaps in our clinical knowledge and highlight opportunities for further research.

Update in Cancer Pain Syndromes

Cancer pain assessment and management are integral to palliative medicine. This paper reviews recent publications in the period 1999-2004 in the broad categories of epidemiology, pain assessment, nonpharmacologic approaches to cancer pain (radiation therapy, anesthetic blocks, palliative surgery and chemotherapy, complementary and alternative medicine), and in nociceptive pain, neuropathic pain, visceral pain, and bone pain.

A Descriptive Review of Neuropathic-Like Pain After Burn Injury

This study reviews the natural history of neuropathic-like pain after burn injury. We undertook a retrospective chart review during a 24-month period of patients treated at an outpatient burn center. The medical records of patients with neuropathic-like pain complaints, including the sensation of pins and needles, burning, stabbing, shooting, or "electric" sensations, were included for analysis. Medical and demographic data were collected. We identified 72 patients for inclusion in the study. The age was 44 +/- 2 years (mean +/- SEM), and TBSA burned was 18 +/- 3%. The first complaint of neuropathic-like symptoms was at 4.3 +/- 0.5 months after injury. Documentation of improvement in the symptoms occurred at 7.0 +/- 0.8 months. Symptoms persisted for 13.1 +/- 2.2 months after the injury. Patients were followed for 14.5 +/- 2.2 months. Documented initial pain severity score was 7 +/- 1 of 10. Typical exacerbating factors included temperature change, dependent position, light touch, and weight-bearing activities. Common alleviating factors included rest, massage, compression garment use, and elevation. Treatment regimens often included gabapentin (38%) and steroid injections (21%). Hypertrophic scarring (43%), pruritus (40%), and psychiatric diagnoses (36%) were common associated problems. There is a patterned natural history for neuropathic-like pain after burn injury. This clinical entity involves significant pain complaints and persists, on average, for greater than 1 year after injury, which underscores the importance of long-term outpatient care after burn injury. Furthermore, an understanding of the natural history will assist clinicians in prognosticating and caring for burn survivors with pain after wound closure.

Perioperative management of chronic pain patients with opioid dependency

PURPOSE OF REVIEW

In this article, we discuss the perioperative anesthesia and pain management of patients with chronic pain receiving chronic opioid administration. In our practice we may expect to be confronted with opioid-dependent patients in routine anesthesia practice and should acquire specific knowledge and skills to effectively manage the perioperative and acute pain management issues that arise.

RECENT FINDINGS

The number of patients treated chronically with opioids has increased steadily over the past decade; currently about 10% of all chronic-pain patients are treated with opioids. As these patients are no longer confined to terminally ill cancer patients, growing numbers of these patients are facing surgical interventions.

SUMMARY

In our clinical practice, we should employ multimodal pain management therapy by using an around-the-clock regimen of nonsteroidal anti-inflammatory drugs, cyclooxygenase-2 inhibitors, acetaminophen, and regional blockade. Dosing regimens should be individualized to optimize efficacy while minimizing the risk of adverse events.

Transcutaneous Electrical Nerve Stimulation for the Management of Neuropathic Pain: The Effects of Frequency and Electrode Position on Prevention of Allodynia in a Rat Model of Complex Regional Pain Syndrome Type II

Background and Purpose. Complex regional pain syndrome type II (CPSII) is a painful condition that develops following a nerve injury. Although transcutaneous electrical nerve stimulation (TENS) relieves the pain of CPSII, the stimulation parameters that would best prevent the development of the condition are not known. The purpose of this study was to compare the ability of several different stimulation strategies to reduce the development of allodynia. Subjects. Sprague-Dawley rats were used in the study. Methods. A chronic constriction injury (CCI) to the right sciatic nerve was used to induce allodynia. Two groups of CCI rats received high-frequency TENS to the lumbar paravertebral region with electrodes positioned on the skin overlying either the right or left paraspinal musculature. Two additional groups of CCI rats received low-frequency TENS to acupuncture points in the right or left hind limbs. A fifth group of CCI rats received no TENS intervention. Thermal and mechanical pain thresholds were assessed in the right hind paw before and 12 days after the CCI surgery. The TENS was delivered 1 hour per day beginning on the day of surgery. Results. Daily high-frequency TENS reduced the development of mechanical allodynia in CCI rats, and low-frequency TENS reduced the development of thermal allodynia, but only when TENS was delivered on the left side. Discussion and Conclusion. The results indicate that TENS delivered contralateral to a nerve injury best reduces allodynia development. Comprehensive reduction of allodynia development would require a combination of high- and low-frequency TENS intervention.

Diabetic peripheral neuropathic pain: clinical and quality-of-life issues

Diabetic peripheral neuropathy (DPN) is estimated to be present in 50% of people living with diabetes mellitus (DM). Comorbidities of DM, such as macrovascular and microvascular changes, also Interact with DPN and affect its course. In patients with DM, DPN Is the leading cause of foot ulcers, which in turn are a major cause of amputation in the United States. Although most patients with DPN do not have pain, approximately 11% of patients with DPN have chronic, painful symptoms that diminish quality of life, disrupt sleep, and can lead to depression. Despite the number of patients affected by DPN pain, little consensus exists about the pathophysiology, best diagnostic tools, and primary treatment choices. This article reviews the current knowledge about and presents recommendations for diagnostic assessment of DPN pain based on a review of the literature.