Painful diabetic neuropathy

Diabetic Neuropathic Cachexia in a Young Woman

Profound weight loss with painful symmetrical peripheral neuropathy in diabetic patients was first described as diabetic neuropathic cachexia more than 4 decades ago. It is a distinct type of diabetic peripheral neuropathy that occurs in the absence of other microvascular and autonomic complications of diabetes. The mechanism and precipitating cause are unknown. It was reported to have good prognosis with spontaneous recovery within months to 2 years. However, it was frequently missed by clinicians because the profound weight loss is the most outstanding complaint, rather than the pain, numbness, or weakness. This often leads to extensive investigation to exclude more sinister causes of weight loss, particularly malignancy. We report a case of a young woman with well-controlled diabetes who presented with profound unintentional weight loss (26 kg), symmetrical debilitating thigh pain, and clinical signs of peripheral neuropathy. As the disease entity may mimic an inflammatory demyelinating cause of neuropathy, she was treated with a trial of intravenous immunoglobulin, which failed to give any significant benefit. However, she recovered after 6 months without any specific treatment, other than an antidepressant for the neuropathic pain and ongoing rehabilitation.

Decompression nerve surgery for diabetic neuropathy: a structured review of published clinical trials

AIM

To assess lower extremity decompression nerve surgery (DNS) to treat the consequences of diabetic distal symmetric peripheral neuropathy (DPN).

RESEARCH DESIGN AND METHODS

MEDLINE, PubMed, and related registries were searched through December 2017 to identify randomized, quasi-randomized or observational trials that evaluated the efficacy of lower extremity DNS on pain relief (primary outcome) or other secondary outcomes. Observational studies were included, given investigators' reluctance to use sham surgery controls. Outcome effect size was estimated, and a weighted average was calculated.

RESULTS

Eight of 23 studies evaluated pain relief, including a double-blind randomized controlled trial (with a sham surgery leg), an unblinded trial with a nonsurgical control leg, and 6 observational studies. All reported substantial pain relief post-DNS with average effect sizes between two and five. Unexpectedly, the double-blind trial showed improvement in the sham leg comparable to the DNS leg and exceeding the improvement observed in the nonsurgical leg in the unblinded study. Sensory testing showed generally favorable results supporting DNS, and nerve conduction velocities increased post-DNS relative to deterioration in controls. Ultrasound revealed fusiform nerve swelling near compression sites. Morphological results of DNS were generally favorable but inconsistent, whereas hemodynamic measures showed a positive effect on arterial parameters, as did transcutaneous oximetry (improved microcirculation). The incidence of initial and recurrent neuropathic diabetic foot ulcers appeared reduced post-DNS relative to the contralateral foot (borderline significant).

CONCLUSION

The data remain insufficient to recommend DNS for painful DPN, given conflicting and unexpectedly positive results involving sham surgery relative to unblinded controls. The generally supportive sensory and nerve conduction results are compromised by methodological issues, whereas more favorable results support DNS to prevent new or recurrent neuropathic foot ulcers. Future studies need to clarify subject selection vis-à-vis DPN vs superimposed compressed nerves, utilize appropriate validated instruments, and readdress use of sham surgical controls in light of recent results.

Strategies for the diagnosis and treatment of neuropathic pain secondary to diabetic peripheral sensory polyneuropathy

This article proposes a strategy for the diagnosis and treatment of neuropathic pain due to diabetic peripheral sensory neuropathy, based on 15 years of experience in French pain-management centres and on the available literature. In the diabetic patient with chronic pain in the lower limbs, the first step in the diagnostic process is to identify the neuropathic origin of the pain. The second step is to evaluate the patient's medical history and make a rigorous baseline assessment of the neuropathic pain symptoms to determine an effective pain-management strategy. In the third step, adequate and well-tolerated treatment directed towards a variety of painful symptoms is selected, taking into account other co-morbidities such as anxiety and depression. This report reports on the clinical aspects of neuropathic pain exhibited by patients with diabetic sensory polyneuropathy, and the key factors in their diagnosis and treatment, based on the results of meta-analyses and on a recent expert consensus.

[Implementation of a standardized perioperative pain management concept in three hospitals of a consortium]

BACKGROUND

Provision of sufficient perioperative pain therapy is an obligation in the clinical management of patients suffering from pain. The implementation of a standardized pain management concept was planned to be introduced in the clinical routine. The results of three hospitals are shown.

MATERIAL AND METHODS

The concept included tools which gave information about legal aspects and basic fundamentals of pain relief, management modules regarding agreements on the implementation of perioperative pain therapy, instruments to measure pain intensity, assigning accountability and documentation modules. Questionnaires were carried out according to Picker.

RESULTS

The project revealed that, according to the Picker questionnaire, about 50% of the patients treated in the hospitals had pain, 30-40% still had intensive pain during the stay in hospital and 90% of the patients received pain relief medication within 10 min of the request. More than 78% of the patients thought the hospital staff did their best to relieve the pain and over 92% found the pain treatment adequate.

CONCLUSION

It was possible to implement a standardized perioperative pain therapy concept in three hospitals of a consortium. Whether an adequate pain relief can be improved with the help of standard measurements and documentation, could not be evaluated in this study.

A review of the epidemiology of painful diabetic peripheral neuropathy, postherpetic neuralgia, and less commonly studied neuropathic pain conditions

Although the burden of neuropathic pain is well-recognized, the descriptive epidemiology of specific neuropathic pain conditions has not been well-described. While painful diabetic peripheral neuropathy and postherpetic neuralgia have been widely evaluated, many other peripheral and central neuropathic pain syndromes have been less frequently studied. This review summarizes incidence and/or prevalence information about two relatively frequent neuropathic pain conditions-painful diabetic peripheral neuropathy and postherpetic neuralgia-and similarly summarizes the more limited epidemiologic information available for other peripheral and central neuropathic pain conditions. The data suggest that while our knowledge is still incomplete, the high frequency of several of these conditions in specific populations should be considered an important impetus for further studies designed to evaluate their contribution to the overall burden of neuropathic pain.

Development and validity testing of the neuropathy total symptom score-6: questionnaire for the study of sensory symptoms of diabetic peripheral neuropathy

OBJECTIVE

The aim of this study was to develop and validate a neuropathy sensory symptom scale, the Neuropathy Total Symptom Score-6 (NTSS-6), which evaluates individual neuropathy sensory symptoms in patients with diabetes mellitus (DM) and diabetic peripheral neuropathy (DPN) in clinical trials, with the intent of distinguishing a response to therapy.

METHODS

The NTSS-6 questionnaire was developed to evaluate the frequency and intensity of individual neuropathy sensory symptoms identified frequently by patients with DPN (ie, numbness and/or insensitivity; prickling and/or tingling sensation; burning sensation; aching pain and/or tightness; sharp, shooting, lancinating pain; and allodynia and/or hyperalgesia). The NTSS-6 was administered 8 times over a 1-year period to DPN patients. The NTSS-6's reliability (determined by internal consistency and test-retest reproducibility), construct validity, convergent validity, and minimally clinically important differences (MCIDs) were determined.

RESULTS

The NTSS-6 was administered to a total of 205 patients at 10 centers in the United States, Canada, Belgium, Germany, Hungary, Croatia, Slovenia, and the United Kingdom. Internal consistency was demonstrated at all 8 visits (Cronbach's alpha > 0.7). Test-retest reproducibility (intraclass correlation coefficient >0.9) was observed during the baseline period and at end point. Construct validity was demonstrated by statistically significant correlations between the NTSS-6 total score and the Neuropathy Symptoms and Change (NSC) score (r = 0.773-0.885, P < 0.001). Convergent validity was demonstrated by statistically significant correlations between the change in NTSS-6 total scores and the following: change in NSC scores (r = 0.519-0.708, P < 0.001); change in Neuropathy Impairment Score of the Lower Limbs and composite nerve function scores (r = 0.188-0.202, P < 0.007), and categories of the Clinical Global Impressions (r = 0.402, P < 0.001). The within- and between-groups MCIDs for the total NTSS-6 total scores were -1.26 and 0.97 points, respectively. The mean (SD) within-group MCID for all patients who improved on the Clinical Global Impression was -2.29 (3.4) points.

CONCLUSIONS

The NTSS-6 provided a valid assessment of neuropathy sensory symptoms in this sample of patients with DM and DPN, which suggests that it may be useful for symptom evaluation in clinical trials and practice. The NTSS-6 showed internal consistency, test-retest reliability, and construct validity. There was also convergent validity of the scores, indicating that the NTSS-6 may be a suitable questionnaire for clinical trials that evaluate symptoms of DPN in this well-defined patient population.

Validation of a modified version of the Brief Pain Inventory for painful diabetic peripheral neuropathy

Neuropathic pain is the focus of current clinical research, clinical identification, and treatment. It is unique from nociceptive pain and requires evaluation of the relevance and utility of common pain measures created for other painful conditions. This study evaluated the psychometric properties of a modified Brief Pain Inventory (BPI) for patients with painful diabetic peripheral neuropathy (BPI-DPN). Participants were patients with painful DPN (n = 255) enrolled in a DPN Burden of Illness survey referred through 17 outpatient settings (primary care physicians, endocrinologists, neurologists, and anesthesiologists). Patients completed the BPI-DPN and self-report measures of health-related quality of life, mood sleep, and health care use. Construct, criterion and discriminant validity, and internal consistency reliability were evaluated. Principal axis factoring with oblimin rotation revealed two interpretable factors (eigenvalues > 1.0), consistent with most published BPI validation studies: a severity scale comprising the four BPI Severity items and an interference scale comprising the seven Interference items, which satisfied criteria for interpretability and model fit. Cronbach's alpha was high (0.94) for both scales. Mean pain Severity was highly correlated with Bodily Pain from the Medical Outcomes Study Short Form-12, version 2 (r(s) = 0.63, P < .001), the Pain/Discomfort item in the Euro-QoL (r(s) = 0.58, P < .001), and a verbal rating scale measure of pain severity (r(s) = 0.74, P < .001). Individual BPI-DPN Interference domains were moderately correlated (r(s)'s > 0.5, P < .001) with analogous measures, and the Sleep Interference item had a high, significant association with the three primary Medical Outcome Study-Sleep scale subscales (r(s)'s = 0.66-71, P < .001). Worst Pain and Interference ratings were significantly associated with hospital use and outpatient visits because of DPN. These results replicate, in a pure peripheral neuropathic pain condition, the BPI psychometric characteristics documented in populations with nociceptive or mixed pain conditions. The BPI-DPN is a promising instrument in the evaluation of painful DPN.

Chronic neuropathic pain. Mechanisms, diagnosis, and treatment

BACKGROUND

The management of chronic pain represents a significant public health issue in the United States. It is both costly to our health care system and devastating to the patient's quality of life. The need to improve pain outcomes is reflected by the congressional declaration of the present decade as the "Decade of Pain Control and Research," and the acknowledgment in January 2001 of pain as the "fifth vital sign" by the Joint Commission of Healthcare Organizations.

REVIEW SUMMARY

At present, therapeutic options are largely limited to drugs approved for other conditions, including anticonvulsants, antidepressants, antiarrhythmics, and opioids. However, treatment based on the underlying disease state (eg, postherpetic neuralgia, diabetic neuropathy) may be less than optimal, in that 2 patients with the same neuropathic pain syndrome may have different symptomatology and thus respond differently to the same treatment. Increases in our understanding of the function of the neurologic system over the last few years have led to new insights into the mechanisms underlying pain symptoms, especially chronic and neuropathic pain.

CONCLUSIONS

The rapidly evolving symptom- and mechanism-based approach to the treatment of neuropathic pain holds promise for improving the quality of life of our patients with neuropathic pain.

Effectiveness of frequency-modulated electromagnetic neural stimulation in the treatment of painful diabetic neuropathy

AIMS/HYPOTHESIS

The largely unsatisfactory results reported for the pharmacological treatment of diabetic neuropathy has spurred the search for alternative therapies. The aim of this study was to evaluate the efficacy of frequency-modulated electromagnetic neural stimulation (FREMS) as a novel treatment for painful diabetic neuropathy.

METHODS

Patients (n=31) with painful neuropathy associated with decreased nerve conduction velocity (<40 m/s) and increased vibration perception threshold (>25 V) were enrolled in a randomised, double-blind, crossover study designed to compare the effects of FREMS with those of placebo. Each patient received two series of ten treatments of either FREMS or placebo in random sequence, with each series lasting no more than 3 weeks. The primary efficacy end point was the change in pain measured by a visual analogue scale (VAS).

RESULTS

FREMS induced a significant reduction in daytime and night-time VAS pain score (all p<0.02). Furthermore, FREMS induced a significant increase in sensory tactile perception, as assessed by monofilament; a decrease in foot vibration perception threshold, as measured by a biothesiometer; and an increase in motor nerve conduction velocity (all p<0.01). No significant changes were observed after placebo. Comparison of measurements at the 4-month follow-up with those at baseline revealed that a significant benefit persisted for all measures that showed an improvement at the end of treatment, with an additional improvement in quality of life evaluated by the Short Form-36 questionnaire (all p<0.05). No significant side effects were recorded during the study.

CONCLUSIONS/INTERPRETATION

FREMS is a safe and effective therapy for neuropathic pain in patients with diabetes and is able to modify some parameters of peripheral nerve function.

Validation of a modified version of the brief pain inventory for painful diabetic peripheral neuropathy

Neuropathic pain is the focus of current clinical research, clinical identification, and treatment. It is unique from nociceptive pain and requires evaluation of the relevance and utility of common pain measures created for other painful conditions. This study evaluated the psychometric properties of a modified Brief Pain Inventory (BPI) for patients with painful diabetic peripheral neuropathy (BPI-DPN). Participants were patients with painful DPN (n=255) enrolled in a DPN Burden of Illness survey referred through 17 outpatient settings (primary care physicians, endocrinologists, neurologists, and anesthesiologists). Patients completed the BPI-DPN, and self-report measures of health-related quality of life, mood sleep, and healthcare utilization. Construct, criterion and discriminant validity, and internal consistency reliability were evaluated. Principal axis factoring with oblimin rotation revealed two interpretable factors (eigenvalues>1.0), consistent with most published BPI validation studies; a severity scale comprising the four BPI Severity items and an interference scale comprising the seven Interference items, which satisfied criteria for interpretability and model fit. Cronbach's alpha was high (0.94) for both scales. Mean pain Severity was highly correlated with Bodily Pain from the Medical Outcomes Study Short Form-12, version 2 (rs=0.63, P < 0.001), the Pain/Discomfort item in the Euro-QoL (rs=0.58, P < 0.001), and a verbal rating scale measure of pain severity (rs=0.74, P < 0.001). Individual BPI-DPN Interference domains were moderately correlated (rs's >0.5, P < 0.001) with analogous measures, and the Sleep Interference item had a high, significant association with the three primary Medical Outcome Study-Sleep scale subscales (rs's=0.66-71, P < 0.001). Worst Pain and Interference ratings were significantly associated with hospital utilization and outpatient visits due to DPN. These results replicate, in a pure peripheral neuropathic pain condition, the BPI psychometric characteristics documented in populations with nociceptive or mixed pain conditions. The BPI-DPN is a promising instrument in the evaluation of painful DPN.

Chronic painful peripheral neuropathy in an urban community: a controlled comparison of people with and without diabetes

AIMS

A cross-sectional study has been performed in order to estimate the prevalence, severity, and current treatment of chronic painful peripheral neuropathy (CPPN) in people with diabetes in the community.

METHODS

Using a structured questionnaire and examination we have assessed these factors in a community sample of people with diabetes (n=350) and compared them with 344 age- and sex-matched people without diabetes from the same locality.

RESULTS

The prevalence of CPPN was estimated to be 16.2%[95% confidence interval (CI): 6.8-16%] in people with diabetes compared with 4.9% (95% CI: 2.6-7.2%) in the control sample (P < 0.0001). Diabetic subjects with and without CPPN did not differ in age, sex, type and duration of diabetes, body mass index, smoking status and glycaemic control. However, CPPN diabetic subjects had significantly higher Visual Analogue Scale (VAS) scores for pain over the preceding 24 h [median (interquartile range) 3.5 (1.5-6.7) cm vs. 0.7 (0-3.9) cm, P < 0.0001]. Also, the total McGill Pain Questionnaire Score (a measure of pain quality and severity) was 18 (13-31.5) vs. 10 (4-16) (P < 0.0001). Of patients with diabetes and CPPN, 12.5% (7/56) had never reported their symptoms to their treating physician and 39.3% (22/56) had never received any treatment for their painful symptoms.

CONCLUSIONS

CPPN is common, often severe but frequently unreported and inadequately treated.

Diabetic neuropathy: the painful foot

Diabetic neuropathy typically present as a mixture of sensory, motor and autonomic involvement. The development and severity of the neuropathy varies. This article briefly reviews the types of diabetic neuropathy and their relationship to pain and discusses the proposed etiologies.

Efficacy of Oxcarbazepine in the Treatment of Painful Diabetic Neuropathy

OBJECTIVES

To evaluate the safety, tolerability, and efficacy of oxcarbazepine in the treatment of painful diabetic neuropathy.

METHODS

This was an open-label, 9-week trial, consisting of a 1-week prospective Screening Phase followed by an 8-week Treatment Phase. Treatment with oxcarbazepine was initiated at 150 mg/day, and the daily dose was doubled on a weekly basis and titrated to tolerability over 4 weeks, up to 1200 mg/day. This was followed by a 4-week fixed-dose Maintenance Phase, during which patients were maintained on oxcarbazepine at 1200 mg/day or highest tolerated dose. The primary efficacy variable was the change in the weekly pain rating assessed on the Visual Analog Scale (VAS) of the short-form McGill Pain Questionnaire between the Screening Phase and the Treatment Phase. All analyses were performed on the intent-to-treat population.

RESULTS

Thirty patients were enrolled in the trial. The mean daily oxcarbazepine dose during the Maintenance Phase was 814 mg. The mean VAS score dropped from 66.3 during the Screening Phase to 34.3 at the end of the trial (P = 0.0001), for a mean reduction of 48.3%. In addition, there were significant improvements in the total pain score and present pain intensity. Oxcarbazepine was well tolerated, with the most common adverse events consisting of drowsiness and dizziness.

DISCUSSION

The results suggest that oxcarbazepine administered as monotherapy is an efficacious and safe option for the symptomatic treatment of pain associated with symmetrical diabetic neuropathy. These results will need to be confirmed in large, double-blind, placebo-controlled, randomized clinical trials.

Pain in diabetic neuropathy case study: whole patient management

Painful diabetic peripheral neuropathy (DPN) is described as a superficial burning pain associated with other positive and/or negative sensory systems affecting the feet and lower extremities. It is one of the most commonly encountered neuropathic pain syndromes in clinical practice. Presentation may be complicated by multiple symptoms, including allodynia, hyperalgesia, other less well characterized dysesthesias, and serious disruption of social functioning and mood. Peripheral nerve function may deteriorate, which can account for patient reports of diminution of pain after several years of follow-up. Although current understanding holds that the pathogenesis of DPN is multifactorial in nature, long-term studies have shown that rigorous glycemic control is the most relevant factor in clinical intervention and can delay the onset and slow the progression of neuropathy. In addition to glycemic control, other treatment approaches must be examined in order to restore quality of life for patients experiencing painful DPN. Differential diagnosis is required to isolate DPN from other unexplained chronic pain. Neurologic testing in painful DPN is an area of active research and is used to assess the neurologic pathways giving rise to the pain, the degree of neural damage and the degree of subclinical damage. Current treatment options for DPN include mainly antidepressants and anticonvulsants, with other agents such as tramadol, dextromethorphan and memantine being employed or studied. This review article includes a case study of a patient with painful DPN to demonstrate the current management strategies for this neuropathic pain syndrome.

Hyperosmolar Solutions Selectively Block Action Potentials in Rat Myelinated Sensory Fibers: Implications for Diabetic Neuropathy

Diabetic neuropathy is a common complication of diabetes mellitus patients. It is a wide range of abnormalities affecting proximal and distal peripheral sensory and motor nerves. Although plasma hyperosmolality is a common finding in diabetes mellitus, the effects of hyperosmolality on conduction of various sensory signal components have not been addressed in detail. Here we show that in rat dorsal root ganglion (DRG) preparations from normal rats, hyperosmolar solutions (360 mmol/kg, containing increased glucose, sucrose, NaCl, or mannitol) produce a selective block of signal propagation in myelinated sensory A-fibers. In compound action potential (CAP) recordings with suction electrodes, peak A-fiber CAP amplitude was selectively decreased (20%), while the C-fiber peak remained intact or was slightly increased. Hyperosmolar solutions had smaller effects on conduction velocity (CV) of both A- and C-fibers (approximately 5% decrease). Hyperosmolality-induced CAP changes could not be observed during recordings from isolated spinal nerves but were evident during recordings from desheathed spinal nerves. In intracellular recordings, hyperosmolar solutions produced a block of spinal nerve-evoked action potential invasion into the somata of some A-fiber neurons. Removal of extracellular calcium completely prevented the hyperosmolality-induced CAP decreases. Based on these data, we propose that the decreased CAP amplitudes recorded in human patients and in animal models of diabetes are in part due to the effects of hyperosmolality and would depend on the extracellular osmolality at the time of sensory testing. We also hypothesize that hyperosmolality may contribute to both the sensory abnormalities (paresthesias) and the chronic pain symptoms of diabetic neuropathy.

Epidemiology and impact on quality of life of postherpetic neuralgia and painful diabetic neuropathy

OBJECTIVE

This article reviews the prevalence, risk factors, natural history, and impact on quality of life of painful diabetic neuropathy (PDN) and postherpetic neuralgia (PHN).

DISCUSSION

Diabetes mellitus afflicts more than 14 million persons in the U.S. An estimated 20% to 24% of these persons experience PDN. Data on risk factors for PDN are limited, but duration of diabetes mellitus and poor glycemic control are probably important factors. Painful diabetic neuropathy may interfere with general activity, mood, mobility, work, social relations, sleep, leisure activities, and enjoyment of life. Herpes zoster strikes an estimated 800,000 persons each year in the U.S., most of whom are elderly or immunosuppressed. Using pain at 3 months after rash onset as a definition of PHN, between 25% and 50% of adults older than 50 years develop PHN, depending on early antiviral therapy for herpes zoster. Increasing age, greater pain and rash severity, greater degree of sensory impairment, and psychological distress are risk factors for PHN. Postherpetic neuralgia may cause fatigue, insomnia, depression, anxiety, interference with social roles and leisure activity, and impaired basic and instrumental activities of daily living.

CONCLUSIONS

Both conditions are common complications of their underlying disorders and can profoundly diminish the quality of life of affected persons.

Heritability of nociception. III. Genetic relationships among commonly used assays of nociception and hypersensitivity

We and others have previously demonstrated that nociception in the mouse is heritable. A genetic correlation analysis of 12 common measures of nociception among a common set of inbred strains revealed three major clusters (or 'types') of nociception in this species. In the present study, we re-evaluated the major types of nociception and their interrelatedness using ten additional assays of nociception and hypersensitivity, including: three thermal assays (tail withdrawal from 47.5 degrees C water or -15 degrees C ethanol; tail flick from radiant heat), two chemical assays of spontaneous nociception (bee venom test; capsaicin test) and their subsequent thermal hypersensitivity states (including contralateral hypersensitivity in the bee venom test), a mechanical nociceptive assay (tail-clip test), and a mechanical hypersensitivity assay (intrathecal dynorphin). Confirming our earlier findings, the results demonstrate distinct thermal and chemical nociceptive types. It is now clear that mechanical hypersensitivity and thermal hypersensitivity are genetically dissociable phenomena. Furthermore, we now see at least two distinct types of thermal hypersensitivity: afferent-dependent, featuring a preceding significant period of spontaneous nociceptive behavior associated with afferent neural activity, and non-afferent-dependent. In conclusion, our latest analysis suggests that there are at least five fundamental types of nociception and hypersensitivity: (1) baseline thermal nociception; (2) spontaneous responses to noxious chemical stimuli; (3) thermal hypersensitivity; (4) mechanical hypersensitivity; and (5) afferent input-dependent hypersensitivity.

Assessment of pain and health-related quality of life in slowly progressive neuromuscular disease

Few studies have examined the effect of pain on the quality of life of individuals with slowly progressive neuromuscular disease (NMD). The purpose of this study was to determine the frequency and extent to which subjects with slowly progressive NMD report pain and the association between pain and health-related quality of life in persons with NMD. The study design was a descriptive, nonexperimental survey. Of a total of 1,432 subjects with slowly progressive NMDs recruited from a university-based NMD clinic and the membership rosters of worldwide NMD support organizations, 859 agreed to participate. The primary measurement tool used was the Medical Outcomes Study SF-36 health survey. Our results indicated that, with the exception of adult spinal muscular atrophy (SMA), the frequency and severity of pain reported in slowly progressive NMDs was significantly greater than levels of pain reported by the general US population and was comparable to pain reported by subjects with osteoarthritis and chronic low back pain. There was a significant correlation between increased pain and lower levels of general health, vitality, social function, and physical role. Pain was moderately associated with increased fatigue, inability to cope adequately with stress, and sleep disturbance. In conclusion, with the exception of adult SMA, the frequency and severity of pain reported in slowly progressive NMDs was significant.

Emerging cell and molecular strategies for the study and treatment of painful peripheral neuropathies

Pharmacologic treatment for the symptoms of painful neuropathy has been problematic, because there has been limited understanding of the underlying etiologies and systemic levels that an effective dose can have on multiple side effects. The use of molecular methods, such as gene deletion from knockout mice and cellular minipumps for delivery of biologic antinociceptive molecules, has led to a better understanding of the underlying mechanisms of the induction of intractable neuropathic pain. The initiation of an excitatory cascade after injury or disease leads to the induction of various second messenger systems, loss or down-regulation of the endogenous inhibitory spinal GABA system and central sensitization, causing such pain. The development and use of cellular minipumps, immortalized cell lines bioengineered to secrete various antinociceptive molecules for the reversal of neuropathic pain, makes cellular therapy a strategy for clinical use in the next few years. The development of molecular "disimmortalization" technologies will make the use of such engineered cell lines safe for human use. Direct somatic gene transfer for neuropathic pain will eventually overcome the problems associated with transplantation of non-autologous and xenogenic cells. These virus-mediated methods, although at the early stages of evolution and use, offer large-scale production of biologic agents that can be conveniently and confidently used for the long-term relief of chronic neuropathic pain in a clinical setting, without systemic effects or surgical interventions.

Painful diabetic neuropathy

Chronic painful diabetic neuropathy can cause a variety of challenges, particularly in successful treatment. The pain, which can last for years, can severely impair quality of life. Management is difficult, although the careful use of drugs can be significantly beneficial. Tricyclic and anticonvulsant drugs may be effective, with a variety of drugs available as second line agents. Newer non-drug systems such as electrical spinal cord stimulation represent exciting possibilities for the future management of this most difficult diabetic syndrome.