Clinical practice. Painful sensory neuropathy

Defining a Treatable Cause of Erythromelalgia: Acute Adolescent Autoimmune Small-Fiber Axonopathy

Conditions described as "erythromelalgia" and "erythermalgia" are being formally specified by etiological diagnoses that enable the use of disease-modifying as well as symptomatic treatments. We describe an otherwise healthy 20-year-old man with acute-onset erythromelalgia. Severe bilateral distal limb pain and vasodilation persisted despite the use of many antihyperalgesics. Pathological examination of cutaneous nerve endings revealed severe small-fiber predominant axonopathy. Treatment of his apparent autoimmune polyneuropathy with high dose corticosteroids, 4 days of lidocaine infusion, and a prednisone taper cured him. Similarities to other cases allowed us to tentatively characterize a new treatable cause of erythromelalgia; acute adolescent autoimmune small-fiber axonopathy. In this report we evaluate various options for diagnosis and treatment.

Neurotrophins and peripheral neuropathies

Peripheral neuropathy is a common disorder seen in general neurology and neuromuscular specialty clinics. Treatment options directed at the underlying cause can only be offered in a handful of conditions, such as those with possible autoimmune etiology. The remainder fall into the idiopathic or genetic category with no known treatment. This review surveys the evidence supporting the rationale for the therapeutic use of neurotrophins and other neurotrophic factors in these disorders in relationship to the underlying pathobiological process. Previous clinical trials are assessed, and increasingly better understood and appreciated therapeutic potential of neurotrophins is emphasized.

The diagnostic workup of patients with neuropathic pain

Determining the causes of neuropathic pain is more than an epistemological exercise. At its essence, it is a quest to delineate mechanisms of dysfunction through which treatment strategies can be created that are effective in reducing, ameliorating, or eliminating symptomatology. To date, predictors of which patients will develop neuropathic pain or who will respond to specific therapies are lacking, and present therapies have been developed mainly through trial and error. Our current inability to make therapeutically meaningful decisions based on ancillary test data is illustrated by the following: In a study specifically designed to assess the response of patients with painful distal sensory neuropathies to the 5% lidocaine patch, no relationship between treatment response and distal leg skin biopsy, QST, or sensory nerve conduction study results could be established. From a mechanistic perspective, the hypothesis that the lidocaine patch would be most effective in patients with relatively intact epidermal innervation, whose neuropathic pain is presumed attributable to "irritable nociceptors," and least effective in patients with few surviving epidermal nociceptors, presumably with "deafferentation pain," was unproven. The possible explanations are multiple and outside the scope of this review. However, these findings, coupled with the disparity in C-fiber subtype involvement in diabetic small-fiber neuropathy, and the recently reported inability of enzyme replacement therapy in Fabry disease to influence intraepidermal innervation density, while having mixed effects on cold and warm QST thresholds, and beneficial effects on sudomotor findings, when therapeutic benefit was demonstrated, lead one to conclude that the specificity of ancillary testing in neuropathic pain is inadequate at present, and reinforce the aforementioned caveats about inferential conclusions from indirect data. The diagnosis of neuropathic pain mechanisms is in its nascent stages and ancillary testing remains "subordinate," "subsidiary," and "auxiliary" as defined in Webster's Third New International Dictionary. As a consequence of these difficulties, the recent approach by Bennett and his colleagues may have merit. They have hypothesized (and provide data in support) that chronic pain can be more or less neuropathic on a spectrum between "likely," "possible," and "unlikely," based on patient responses on validated neuropathic pain symptom scales, when compared with specialist pain physician certainty of the presence of neuropathic pain on a 100-mm visual analog scale. The symptoms most associated with neuropathic pain were dysesthesias, evoked pain, paroxysmal pain, thermal pain, autonomic complaints, and descriptions of the pain as being sharp, hot, or cold, with high sensitivity. Higher scores for these symptoms correlated with greater clinician certainty of the presence of neuropathic pain mechanisms. Considering each individual patient's chronic pain as being somewhere on a continuum between "purely nociceptive" and "purely neuropathic" may have diagnostic and therapeutic relevance by enhancing specificity, but this requires clinical confirmation. Thus, symptom assessment remains indispensable in the evaluation of neuropathic pain, ancillary testing notwithstanding

Neuropathic low back pain

In this discussion, we hope to advance a clinical approach to low back pain that is more in line with our modern understanding of neuropathic pain. We review the current understanding of normal and pathologic neuroanatomy of the lumbar spine and then outline how pathology in the different structures can lead to neuropathic pain and cause common pain patterns seen in clinical practice. We also detail the available treatments for neuropathic low back pain.

Anti-allodynic property of flavonoid myricitrin in models of persistent inflammatory and neuropathic pain in mice

The aim of the present study was to investigate the effects of myricitrin, a flavonoid with anti-inflammatory and antinociceptive action, upon persistent neuropathic and inflammatory pain. The neuropathic pain was caused by a partial ligation (2/3) of the sciatic nerve and the inflammatory pain was induced by an intraplantar (i.pl.) injection of 20 microL of complete Freund's adjuvant (CFA) in adult Swiss mice (25-35 g). Seven days after sciatic nerve constriction and 24 h after CFA i.pl. injection, mouse pain threshold was evaluated through tactile allodynia, using Von Frey Hair (VFH) filaments. Further analyses performed in CFA-injected mice were paw edema measurement, leukocytes infiltration, morphological changes and myeloperoxidase (MPO) enzyme activity. The intraperitoneal (i.p.) treatment with myricitrin (30 mg/kg) significantly decreased the paw withdrawal response in persistent neuropathic and inflammatory pain and decreased mouse paw edema. CFA injection increased 4-fold MPO activity and 27-fold the number of neutrophils in the mouse paw after 24 h. Myricitrin strongly reduced MPO activity, returning to basal levels; however, it did not reduce neutrophils migration. In addition, myricitrin treatment decreased morphological alterations to the epidermis and dermis papilar of mouse paw. Together these results indicate that myricitrin produces pronounced anti-allodynic and anti-edematogenic effects in two models of chronic pain in mice. Considering that few drugs are currently available for the treatment of chronic pain, the present results indicate that myricitrin might be potentially interesting in the development of new clinically relevant drugs for the management of this disorder.

Chronic pain and comorbid mood and substance use disorders: a biopsychosocial treatment approach

Chronic pain is a colossal health care problem that is devastating to the individual afflicted with unremitting pain and frustrating to the beleaguered health care provider attempting to adequately manage this multifaceted disease. The biopsychosocial model of pain management is a promising approach that emphasizes evidence-based medication management in conjunction with cognitive-behavioral therapy and a graded exercise program. The patient with chronic pain and concomitant mood and/or substance use disorders is exceptionally challenging. Effective pharmacologic management of pain and comorbid mood disorders, including the thoughtful use of opioids, can have a dramatic effect in improving the quality of life in patients with chronic pain. The high prevalence of chronic pain in our society and the scarcity of experienced pain medicine physicians necessitate the development of a community-based systems approach to this complex patient population.

Neuropathic pain: a practical guide for the clinician

Neuropathic pain, caused by various central and peripheral nerve disorders, is especially problematic because of its severity, chronicity and resistance to simple analgesics. The condition affects 2%-3% of the population, is costly to the health care system and is personally devastating to the people who experience it. The diagnosis of neuropathic pain is based primarily on history (e.g., underlying disorder and distinct pain qualities) and the findings on physical examination (e.g., pattern of sensory disturbance); however, several tests may sometimes be helpful. Important pathophysiologic mechanisms include sodium-and calcium-channel upregulation, spinal hyperexcitability, descending facilitation and aberrant sympathetic-somatic nervous system interactions. Treatments are generally palliative and include conservative nonpharmacologic therapies, drugs and more invasive interventions (e.g., spinal cord stimulation). Individualizing treatment requires consideration of the functional impact of the neuropathic pain (e.g., depression, disability) as well as ongoing evaluation, patient education, reassurance and specialty referral. We propose a primary care algorithm for treatments with the most favourable risk-benefit profile, including topical lidocaine, gabapentin, pregabalin, tricyclic antidepressants, mixed serotonin-norepinephrine reuptake inhibitors, tramadol and opioids. The field of neuropathic pain research and treatment is in the early stages of development, with many unmet goals. In coming years, several advances are expected in the basic and clinical sciences of neuropathic pain, which will provide new and improved therapies for patients who continue to experience this disabling condition.

The pharmacist’s role in managing chronic opioid therapy

Chronic pain is a costly and prevalent problem. Pain, itself, is a symptom. Pain has received attention in the form of health care policy reform, development of assessment tools, and treatment protocols. Chronic pain is an ongoing problem that requires constant monitoring and can be challenging to health care providers and patients. Many barriers exist in treating chronic pain, especially when treating with opioid analgesics. Pharmacists can help in the assessment and treatment of chronic pain. This article discusses the impact of chronic pain, barriers to care, and the role of the pharmacist in managing chronic opioid therapy.

HIV peripheral neuropathy: pathophysiology and clinical implications

One of the most debilitating neurological complications of human immunodeficiency virus (HIV), affecting nearly one in three patients, is painful peripheral neuropathy. Although HIV infection can cause distal sensory polyneuropathy (DSP), the advent of highly active antiretroviral therapy (HAART) to treat HIV infection has resulted in a significant number of patients developing a clinically indistinguishable form of toxic neuropathy. The predominant symptom, regardless of etiology, is excruciating unremitting pain, resistant to pharmacological treatments, that leads to a reduction in the ability to conduct activities of daily living and, eventually, inability to ambulate. Since withdrawal from nucleoside therapy is not typically recommended, a more thorough understanding of the etiology and pathophysiology underlying nucleoside-induced peripheral neuropathy, through basic and clinical research endeavors, will aid in the development of new therapeutic treatments aimed at alleviating or ameliorating pain. This article provides the latest information regarding the pathophysiology and clinical implications of HIV peripheral neuropathy.

Use of tricyclic antidepressants in older patients with painful neuropathies

OBJECTIVE

To describe patterns of use of tricyclic antidepressants (TCAs) (e.g., amitriptyline, nortriptyline) in older patients with painful neuropathies.

RESEARCH DESIGN AND METHODS

Using a large US health insurance claims database, we identified all persons who: (1) received a TCA between 1 January 1999 and 30 June 2001, (2) were aged > or =65 years as of the date of their first prescription for a TCA during this period, and (3) had one or more health care encounters for the treatment of a painful neuropathy in the 30-day period immediately preceding their initial receipt of a TCA. We then examined the prevalence of selected comorbidities and/or concurrent use of medications that might render the prescribing of a TCA inappropriate, based on a listing of contraindications, warnings, and precautions found in the package inserts for these agents. Patterns of TCA use also were examined, based on information on paid claims.

RESULTS

A total of 1,732 patients met all inclusion and exclusion criteria for the study. Their mean age was 74.6 years; 60.3% were women. Amitriptyline was the most frequently prescribed TCA (79.4% of patients). Forty-one percent of study subjects receiving TCAs had conditions--primarily cardiovascular--that render the use of such agents potentially inappropriate. The mean daily dose of TCAs was universally low (about 23 mg).

CONCLUSIONS

The high prevalence of conditions rendering the use of TCAs potentially inappropriate, along with relatively low daily dosages, suggest that many older patients with painful neuropathies who are prescribed these agents may be suboptimally treated.

Relationship of the uterosacral ligament to the sacral plexus and to the pudendal nerve

We describe the anatomy of the uterosacral ligament with respect to the sacral plexus. In six adult female embalmed cadavers, we identified the uterosacral ligament and its lateral nerve relations. Using the ischial spine as the starting point and measuring along the axis of the uterosacral ligament, we noted that the S1 trunk of the sacral plexus passes under the ligament 3.9 cm [95% confidence interval (CI), 2.1-5.8 cm] superior to the ischial spine. The S2 trunk passes under the ligament at 2.6 cm (95% CI; 1.5, 3.6 cm), the S3 trunk passes under the ligament at 1.5 cm (95% CI; 0.7, 2.4 cm), and the S4 trunk passes under the ligament at 0.9 cm (95% CI; 0.3, 1.5 cm) superior to the ischial spine. The pudendal nerve forms lateral to the uterosacral ligament. Our data demonstrate that the S1-S4 trunks of the sacral plexus, not the pudendal nerve, are vulnerable to injury during uterosacral ligament suspension.

Long-lasting neuropathic pain induced by brachial plexus injury in mice: Role triggered by the pro-inflammatory cytokine, tumour necrosis factor α

Brachial plexus avulsion (BPA) resulted in a marked and long-lasting mechanical hypernociception (up to 80 days) in comparison to a sham-operated group, as assessed by Von Frey filaments, in both Swiss and C57/BL6 mice. In the tail-flick test, both Swiss and C57/BL6 mice submitted to BPA showed a significant thermal hypernociception, which persisted for 10 days. Both mechanical and thermal hypernociception following BPA were abolished in tumour necrosis factor alpha (TNFalpha) p55 receptor knockout mice. Moreover, the mechanical hypernociception caused by BPA was inhibited by the local application of the anti-TNFalpha (10 and 100 ng/site) antibody at the time of the surgery or by the intravenous administration (100 microg/kg) of this antibody at the time of the surgery or 4 days after the BPA. A similar inhibition of the mechanical hypernociception was observed when treating mice with the TNFalpha synthesis inhibitor thalidomide (50 mg/kg, s.c.), either at the time of the surgery or 4 days after. The results suggest that the persistent thermal, and especially the persistent mechanical, hypernociception observed following BPA in mice is largely dependent on the generation of TNFalpha. Based on these results, it is possible to suggest that therapeutic strategies for blocking TNFalpha could represent a valuable approach for the treatment of persistent neuropathic pain.

The Level of Small Nerve Fiber Dysfunction Does not Predict Pain in Diabetic Neuropathy: A Study Using Quantitative Sensory Testing

OBJECTIVES

To determine whether small nerve fiber dysfunction predicts pain in diabetic neuropathy using quantitative sensory testing of thermal thresholds.

METHODS

Diabetic patients with or without painful neuropathy (n=191) were studied. Small nerve fiber function was assessed by quantitative sensory testing of cold detection and heat pain thresholds. Subjects were also categorized as being hyperalgesic (<10th percentile) or hyposensitive (>90th percentile) by comparing with normative data. Vibration perception threshold, a large nerve fiber function, was measured using a biothesiometer (Bio-medical Instrument, Newbury, OH).

RESULTS

In the patients with pain, cold stimulus was detected after a greater reduction in temperature from baseline (-3.7 degrees C vs. -0.6 in the no-pain group, P<0.0001). There were no differences between the pain and painless groups in the heat pain tests, with hyperalgesia noted in about 60% of subjects. Vibration perception threshold and loss of ankle reflexes were significant determinants of pain, but together they accounted for only 6.8% of the variance. If these were removed from the model, cold detection threshold became a significant determinant of pain but accounted for only 3.0% of the variance.

CONCLUSIONS

Quantitative sensory testing of small nerve fiber function is a useful test to detect the presence of neuropathy, and overall diabetic patients with neuropathic pain have more sensory loss. However, small nerve fiber abnormalities detected by quantitative sensory testing do not predict the presence of pain in diabetic neuropathy.

Small-Fiber Neuropathy Associated with Capecitabine (Xeloda)-induced Hand-foot Syndrome: A Case Report

Hand-foot syndrome commonly results from treatment with capecitabine and is associated with pain, dysesthesias, paresthesias, and temperature intolerance. The cause of these symptoms in hand-foot syndrome has not been determined. We present the clinical, electrophysiologic, and biopsy data from a patient with capecitabine-induced hand-foot syndrome as supporting evidence implicating small-fiber neuropathy as the cause of these neuropathic symptoms. A patient with stage 4 breast cancer who develops capecitabine-induced hand-foot syndrome is referred for clinical and electrophysiologic testing. Intraepidermal nerve fiber density is assessed. Clinical evaluation demonstrates markedly decreased pain and temperature sensation with preserved strength, proprioception, and light touch. Standard electrodiagnostic testing is normal. The assessment of epidermal nerve fiber density demonstrates marked small-fiber loss both proximally and distally. In conclusion, small-fiber neuropathy is a likely cause of the neuropathic symptoms encountered in capecitabine-induced hand-foot syndrome. Similar clinical, electrophysiologic, and pathologic assessments are needed to confirm this finding in larger populations.

Vulvodynia: a therapeutic challenge

Vulvodynia is a poorly understood, distressing and debilitating disorder. The management of this disorder remains insufficient and the lack of consistent terminology is confusing. The management of classic dysesthetic vulvodynia is fairly straightforward, using drugs effective against chronic neuropathic pain. However, vulvar vestibulitis syndrome remains a therapeutic challenge. A pragmatic approach is recommended for the management of patients with vulvar vestibulitis syndrome. In refractory cases, vestibulectomy has a high success rate, although the evidence is based mainly on small, descriptive studies. Comparative studies of conservative versus surgical management of vulvar vestibulitis syndrome are needed.

The effects of diacerhein on mechanical allodynia in inflammatory and neuropathic models of nociception in mice

In this study we analyzed the systemic antiallodynic properties of diacerhein, a drug used to treat osteoarthritis, in inflammatory and neuropathic models of nociception in mice. The effects of diacerhein were compared with those of gabapentin, a drug used clinically for the management of neuropathic pain. Similar to gabapentin, diacerhein was able to significantly reverse the mechanical allodynia induced by carrageenan. A significant inhibition of carrageenan-induced nociception was also observed when diacerhein was administered by the intrathecal but not by the intraplantar route. The treatment with diacerhein or with gabapentin also inhibited the mechanical allodynia induced by complete Freund's adjuvant (CFA) or after the partial ligation of the sciatic nerve (PLSN). In the same range of doses, diacerhein or gabapentin did not affect the locomotor activity, motor coordination, or body temperature of the animals. The present results indicate that diacerhein produces marked antiallodynic effects in carrageenan and CFA nociception models and also inhibits the neuropathic pain after PLSN, with an efficacy similar to that observed for gabapentin. Diacerhein may be a potentially interesting tool for the management of inflammatory and neuropathic pain.

Duloxetine: A balanced and selective norepinephrine- and serotonin-reuptake inhibitor

PURPOSE

The pharmacology, pharmacokinetics, efficacy, safety, drug interactions, dosage and administration, cost, and place in therapy of duloxetine for major depression, pain from diabetic peripheral neuropathy, and stress urinary incontinence are reviewed.

SUMMARY

Duloxetine is a balanced selective serotonin and norepinephrine-reuptake inhibitor available in the United States for the treatment of major depressive disorder (MDD) and diabetic peripheral neuropathic pain (DPNP). Duloxetine has also been used for the treatment of stress urinary incontinence (SUI). Absorption of duloxetine begins two hours after oral administration, reaching a maximum plasma concentration in six hours. Half-life and volume of distribution are 12 hours and 1640 L, respectively. The recommended dosage of duloxetine is 40-80 mg daily, depending on the indication, preferably split into two doses per day. For the treatment of major depression, duloxetine has achieved remission rates similar to that of existing selective serotonin-reuptake inhibitors (SSRIs). For SUI and pain associated with diabetic peripheral neuropathy, duloxetine has not demonstrated equivalence or superiority to existing therapies. The adverse effects of duloxetine are similar to those of traditional SSRIs. Nausea is common and has been cited as the primary reason for discontinuation of duloxetine in trials. Increases in blood pressure have been mild, but caution should be used in patients with hypertension. Patients with a creatinine clearance of <30 mL/min and patients with hepatic impairment should avoid duloxetine. Duloxetine should not be recommended as first-line therapy for SUI or DPNP. For MDD, duloxetine may be a useful alternative for patients who do not benefit from or are unable to tolerate other antidepressant therapy.

CONCLUSION

Duloxetine has been approved for the treatment of MDD and pain associated with diabetic peripheral neuropathy in adults.

Cutaneous innervation: Form and function

It is useful for dermatologists to know about the innervation of the skin because dysfunction of cutaneous neurons can cause symptoms--such as itching, pain, and paresthesias--that are evaluated by dermatologists. We review the innervation of the skin and update readers about recent neuroscientific discoveries.

Small fibre neuropathies

PURPOSE OF REVIEW

To summarize the recent advances in aetiology, diagnostic assessment, and treatment of small fibre neuropathies.

RECENT FINDINGS

New causes of small fibre neuropathy have been recognized and advances in neurophysiologic and neuropathologic techniques for investigating small fibres have been made, increasing the interest in this field. In particular, skin biopsy proved to be a sensitive method to diagnose small fibre neuropathy. It allows the detection of subclinical abnormalities of peripheral nerve function in patients with diabetes and tongue denervation in patients with burning mouth syndrome. This technique has also been used to demonstrate the neuroprotective effect of erythropoietin in experimental models of neuropathy. Among nonconventional neurophysiologic techniques for investigating small fibres, laser-evoked potential and contact heat-evoked potential stimulators have been developed and deserve particular interest. Several trials on neuropathic pain that is a typical feature of small fibre neuropathies have been performed and guidelines have recently been published.

SUMMARY

Detection of small fibre impairment allows earlier diagnosis of neuropathy and could be used as an outcome measure in future regenerative neuropathy trials. Standardization of skin biopsy can have an important impact on clinical practice and research. Further studies are needed to assess the reliability of current neurophysiologic techniques for testing small fibre function in peripheral neuropathies and the correlation with well established neuropathologic examination.

HIV-associated neuropathic pain: epidemiology, pathophysiology and management

Peripheral neuropathy is associated with numerous systemic illnesses including HIV infection. Neuropathic pain constitutes approximately 25-50% of all pain clinic visits. Distal symmetrical polyneuropathy (DSP) is the most common form of peripheral neuropathy in individuals with HIV infection. DSP is distinguished from other forms of neuropathy on the basis of history and neurological examination. The pain associated with DSP can be debilitating. Therefore, it is important to diagnose HIV-associated DSP properly and treat the neuropathic pain in order to improve quality of life. We review the clinical manifestations, epidemiology, pathophysiology and management strategies for HIV-associated DSP.

The diabetic neuropathies

BACKGROUND

Diabetes remains the most common cause of neuropathy in the United States and is a significant source of morbidity and mortality, accounting for substantial suffering and billions of dollars in health care expenditures each year.

REVIEW SUMMARY

Our insight into the pathophysiology of the diabetic neuropathies has increased considerably over the last decade. aided by advances in the basic science of diabetes itself. A wide variety of potential mechanisms for nerve injury in diabetes has been identified, including the polyol pathway of glucose metabolism, oxidative nerve injury, the deposition of advanced glycosylation end products within the nerve and the effects of vascular insufficiency, among others. Diabetic neuropathy may take a variety of clinical forms beyond the well-known distal symmetric neuropathy, many of which are often misdiagnosed or overlooked entirely, sometimes with serious consequences for the patient. Proper therapy after diagnosis is also critical and may include not only primary management, but also treatment of painful diabetic neuropathy through an expanding repertoire of increasingly effective pharmacologic agents. Though primary treatment trials have not yet provided effective therapies, ongoing and future trials offer continuing promise.

CONCLUSIONS

The diabetic neuropathies are exceedingly common, but often improperly diagnosed and incompletely treated. A proper understanding of the mechanisms underlying these diseases and the clinical recognition of their various forms is highly important as appropriate primary and symptomatic management can substantially reduce the morbidity and mortality associated with these disorders.

Chronic back pain is associated with decreased prefrontal and thalamic gray matter density

The role of the brain in chronic pain conditions remains speculative. We compared brain morphology of 26 chronic back pain (CBP) patients to matched control subjects, using magnetic resonance imaging brain scan data and automated analysis techniques. CBP patients were divided into neuropathic, exhibiting pain because of sciatic nerve damage, and non-neuropathic groups. Pain-related characteristics were correlated to morphometric measures. Neocortical gray matter volume was compared after skull normalization. Patients with CBP showed 5-11% less neocortical gray matter volume than control subjects. The magnitude of this decrease is equivalent to the gray matter volume lost in 10-20 years of normal aging. The decreased volume was related to pain duration, indicating a 1.3 cm3 loss of gray matter for every year of chronic pain. Regional gray matter density in 17 CBP patients was compared with matched controls using voxel-based morphometry and nonparametric statistics. Gray matter density was reduced in bilateral dorsolateral prefrontal cortex and right thalamus and was strongly related to pain characteristics in a pattern distinct for neuropathic and non-neuropathic CBP. Our results imply that CBP is accompanied by brain atrophy and suggest that the pathophysiology of chronic pain includes thalamocortical processes.

Treatment of painful polyneuropathies

The treatment of painful polyneuropathies has begun to improve over the past several years. This is based on an evolving understanding of the pathogenesis related to the development of diabetic neuropathy and other diseases that may lead to peripheral nerve injury. Consensus on evaluation strategies for patients presenting with pain has furthered our ability to define neuropathic pain and accompanying signs and symptoms that may respond to particular therapeutic approaches. Recent therapeutic advances in medical management have demonstrated improved outcomes in pain relief. This, along with lower side effect-related issues, has led to improved compliance and patient satisfaction. The assessment and treatment of comorbid conditions, which include sleep, anxiety, and depression, have further advanced the management of painful polyneuropathies in patients. New antiepileptics, antidepressants, and topical therapies have contributed to improved patient outcomes.

Duloxetine: pharmacoeconomic implications of an antidepressant that alleviates painful physical symptoms

Major depressive disorder (MDD) is a prevalent, chronic, medical disorder that encompasses a broad constellation of symptoms. The salience of painful physical symptoms in depressive presentations is increasingly appreciated. Duloxetine is a novel, potent, balanced, dual monoamine reuptake-inhibitor antidepressant indicated for the symptomatic relief of MDD. Duloxetine is marketed as an antidepressant that has inherent analgesic properties for depressed patients who present with prominent painful physical symptoms. Taken together, available evidence indicates that duloxetine provides a higher probability of, and shorter time to, remission than some antidepressants (e.g., fluoxetine). Duloxetine also offers symptom relief for painful physical symptoms in depressed patients. Pharmacoeconomic and cost-impact modelling analyses should be reformulated to consider duloxetine's symptom-alleviating effect on the somatic dimension of depressive illness.

Small fiber neuropathy: a common and important clinical disorder

Small fiber neuropathy (SFN) is a neuropathy selectively involving small diameter myelinated and unmyelinated nerve fibers. Interest in this disorder has considerably increased during the past few years. It is often idiopathic and typically presents with peripheral pain and/or symptoms of autonomic dysfunction. Diagnosis is made on the basis of the clinical features, normal nerve conduction studies (NCS) and abnormal specialized tests of small nerve fibers. Among others, these tests include assessment of epidermal nerve fiber density, temperature sensation tests for sensory fibers and sudomotor and cardiovagal testing (QSART) for autonomic fibers. Unless an underlying disease is identified, treatment is usually symptomatic and directed towards alleviation of neuropathic pain.

Controlling neuropathic pain in HIV

Neuropathic pain is associated with numerous systemic illnesses, including HIV infection. The diagnosis and management of peripheral neuropathy presents diagnostic and therapeutic challenges. Among various forms of HIV-associated peripheral neuropathies, distal symmetrical polyneuropathy (DSP) is the most common. DSP may be caused or exacerbated by neurotoxic antiretrovirals, particularly the dideoxynucleoside analogues (d-drugs). Selection of appropriate pharmacologic intervention for peripheral neuropathy should be based on efficacy, safety, ease of administration, and cost. We review treatment options for painful HIV neuropathy, including experimental agents studied in recent and ongoing clinical trials.

Controlling Neuropathic Pain in HIV

Neuropathic pain is associated with numerous systemic illnesses, including HIV infection. The diagnosis and management of peripheral neuropathy presents diagnostic and therapeutic challenges. Among various forms of HIV-associated peripheral neuropathies, distal symmetrical polyneuropathy (DSP) is the most common. DSP may be caused or exacerbated by neurotoxic antiretrovirals, particularly the dideoxynucleoside analogues (d-drugs). Selection of appropriate pharmacologic intervention for peripheral neuropathy should be based on efficacy, safety, ease of administration, and cost. We review treatment options for painful HIV neuropathy, including experimental agents studied in recent and ongoing clinical trials.

Laser evoked potentials for assessing sensory neuropathy in human patients

Sensory neuropathy usually impairs tactile sensations related to large myelinated afferents (Abeta) as well as thermal-pain sense related to small myelinated (Adelta) and unmyelinated (C) afferents. By selectively affecting large or small fibres, some sensory neuropathies may also provoke a dissociated sensory loss. Standard nerve conduction studies and somatosensory evoked potentials assess Abeta-fibre function only. Laser pulses selectively excite free nerve endings in the superficial skin layers and evoke Adelta-related brain potentials (LEPs). From earlier studies and new cases we collected data on 270 patients with sensory neuropathy. LEPs often disclosed subclinical dysfunction of Adelta fibres and proved a sensitive and reliable diagnostic tool for assessing small-fibre function in sensory neuropathy.

Painful peripheral neuropathy and its nonsurgical treatment

Treatment of neuropathic pain is the primary focus of management for many patients with painful peripheral neuropathy. Antidepressants and anticonvulsants are the two pharmacological classes most widely studied and represent first-line agents in the management of neuropathic pain. The number of pharmacological agents that have demonstrated effectiveness for neuropathic pain continues to expand. In the current review, we summarize data from randomized, controlled pharmacological trials in painful peripheral neuropathies. Although neuropathic pain management remains challenging because the response to therapy varies considerably between patients, and pain relief is rarely complete, a majority of patients can benefit from monotherapy using a well-chosen agent or polypharmacy that combines medications with different mechanisms of action.

Diabetic neuropathy: Clinical features, etiology, and therapy

Diabetes mellitus is a common cause of peripheral nervous system disorders that manifest in a variety of clinical forms, many of which are often misdiagnosed. Over the past two decades, our understanding of the pathophysiology of diabetic nerve injury has improved remarkably through the elucidation of the important roles of the polyol pathway of glucose metabolism, oxidative injury, advanced glycosylation end-products, vascular insufficiency, and other mechanisms. A large number of clinical treatment trials based upon this abundant scientific data have met with limited success, but ongoing and future trials offer promise for more dramatic success in treating this common cause of morbidity and mortality in the diabetic population.

Nutritional Approaches to Late Toxicities of Adjuvant Chemotherapy in Breast Cancer Survivors

Adjuvant chemotherapy of breast cancer reduces recurrence rates and prolongs survival at the cost of both acute and chronic toxicities. Breast cancer survivors who have received adjuvant chemotherapy may suffer from late effects of chemotherapy including congestive heart failure, neuropathy, premature menopause, and osteoporosis. Nutritional approaches to these problems are distinct in their orientation and success. Study of free radical scavengers for anthracycline-induced cardiomyopathy was born from known pathogenetic mechanisms of cardiotoxicity but has been universally disappointing thus far in clinical trials. Application of agents used for diabetic neuropathy suggests that evening primrose oil, alpha-lipoic acid, and capsaicin may all play a role in the empiric options available to patients with chemotherapy-induced neuropathy. Plant-derived preparations including black cohosh (Actaea racemosa), dong quai (Angelica sinensis), evening primrose (Oenothera biennis), and red clover (Trifolium pretense) are used by patients experiencing hot flashes due to premature menopause despite a paucity of clinical trial data demonstrating either safety or efficacy. Calcium and vitamin D are widely accepted as an effective means to retard bone loss leading to osteoporosis. Nutritional approaches to late effects of breast cancer chemotherapy offer the prospect of preventing or ameliorating these sequelae of treatment. However, except for vitamin D and calcium for prevention of bone loss, current clinical evidence supporting use of nutritional agents remains sparse.