Effects of levetiracetam on chronic pain in multiple sclerosis: results of a pilot, randomized, placebo-controlled study

Neuropathic Pain in the Emergency Setting: Diagnosis and Management

Neuropathic pain, traditionally considered a chronic condition, is increasingly encountered in the emergency department (ED), accounting for approximately 20% of patients presenting with pain. Understanding the physiology and key clinical presentations of neuropathic pain is crucial for ED physicians to provide optimal treatment. While diagnosing neuropathic pain can be challenging, emphasis should be placed on obtaining a comprehensive medical history and conducting a thorough clinical examination. Patients often describe neuropathic pain as a burning or shock-like sensation, leading them to seek care in the ED after ineffective relief from common analgesics such as paracetamol and NSAIDs. Collaboration between emergency medicine specialists, neurologists, and pain management experts can contribute to the development of evidence-based guidelines specifically tailored for the emergency department setting. This article provides a concise overview of the common clinical manifestations of neuropathic pain that may prompt patients to seek emergency care.

Preemptive Levetiracetam Decreases Postoperative Pain: A Double-Blind, Randomised, Control Trial

Background Previously many studies have found the use of anti-epileptic drugs such as pregabalin, carbamazepine, and gabapentin in pain management. In addition, levetiracetam (LEV), an effective anti-epileptic drug, has shown analgesic effects in animal models. We aimed to evaluate the effect of oral LEV as pre-emptive analgesia in patients who underwent laparoscopic cholecystectomy under general anaesthesia and postoperative fentanyl requirements. Material and methods Forty-two patients of the American Society of Anaesthesiologists (ASA) grade I and II of either gender posted for elective laparoscopic cholecystectomy surgery were included in this double-blind, randomised, placebo-controlled study. Patients were divided into two equal groups of 21 each to receive either tablet LEV 500 mg or a matching placebo tablet, given 1 hour before surgery. Postoperative pain was assessed by a visual analogue scale (0-100 mm), where 0 meant no pain and 100, worst pain. In addition, patients received IV fentanyl as rescue analgesia during the first 24 hours of the postoperative period. Results Nineteen patients in the LEV group and 20 in the placebo group completed the study. Patients in the LEV group had significantly lower pain scores at all time intervals except 0 hours and reduced fentanyl consumption postoperatively in the first 24 hours (p<0.05). Side effects were comparable in both groups. Conclusion A single, preoperative dose of oral LEV 500 mg significantly decreases post-surgical pain and fentanyl demand as rescue analgesia in elective laparoscopic cholecystectomy.

Central Neuropathic Pain Syndromes: Current and Emerging Pharmacological Strategies

Central neuropathic pain is caused by a disease or lesion of the brain or spinal cord. It is difficult to predict which patients will develop central pain syndromes after a central nervous system injury, but depending on the etiology, lifetime prevalence may be greater than 50%. The resulting pain is often highly distressing and difficult to treat, with no specific treatment guidelines currently available. This narrative review discusses mechanisms contributing to central neuropathic pain, and focuses on pharmacological approaches for managing common central neuropathic pain conditions such as central post-stroke pain, spinal cord injury-related pain, and multiple sclerosis-related neuropathic pain. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids have some evidence for efficacy in central neuropathic pain. Medications from other pharmacologic classes may also provide pain relief, but current evidence is limited. Certain non-pharmacologic approaches, neuromodulation in particular, may be helpful in refractory cases. Emerging data suggest that modulating the primary afferent input may open new horizons for the treatment of central neuropathic pain. For most patients, effective treatment will likely require a multimodal therapy approach.

Levetiracetam Mechanisms of Action: From Molecules to Systems

Epilepsy is a chronic disease that affects millions of people worldwide. Antiepileptic drugs (AEDs) are used to control seizures. Even though parts of their mechanisms of action are known, there are still components that need to be studied. Therefore, the search for novel drugs, new molecular targets, and a better understanding of the mechanisms of action of existing drugs is still crucial. Levetiracetam (LEV) is an AED that has been shown to be effective in seizure control and is well-tolerable, with a novel mechanism of action through an interaction with the synaptic vesicle protein 2A (SV2A). Moreover, LEV has other molecular targets that involve calcium homeostasis, the GABAergic system, and AMPA receptors among others, that might be integrated into a single mechanism of action that could explain the antiepileptogenic, anti-inflammatory, neuroprotective, and antioxidant properties of LEV. This puts it as a possible multitarget drug with clinical applications other than for epilepsy. According to the above, the objective of this work was to carry out a comprehensive and integrative review of LEV in relation to its clinical uses, structural properties, therapeutical targets, and different molecular, genetic, and systemic action mechanisms in order to consider LEV as a candidate for drug repurposing.

Symptomatic and restorative therapies in neuromyelitis optica spectrum disorders

Neuromyelitis optica spectrum disorders (NMOSD) are a group of autoimmune inflammatory conditions that primarily target the optic nerves, spinal cord, brainstem, and occasionally the cerebrum. NMOSD is characterized by recurrent attacks of visual, motor, and/or sensory dysfunction that often result in severe neurological deficits. In recent years, there has been a significant progress in relapse treatment and prevention but the residual disability per attack remains high. Although symptomatic and restorative research has been limited in NMOSD, some therapeutic approaches can be inferred from published case series and evidence from multiple sclerosis literature. In this review, we will discuss established and emerging therapeutic options for symptomatic treatment and restoration of function in NMOSD. We highlight NMOSD-specific considerations and identify potential areas for future research. The review covers pharmacologic, non-pharmacologic, and neuromodulatory approaches to neuropathic pain, tonic spasms, muscle tone abnormalities, sphincter dysfunction, motor and visual impairment, fatigue, sleep disorders, and neuropsychological symptoms. In addition, we briefly discuss remyelinating agents and mesenchymal stem cell transplantation in NMOSD.

[Neuropathic pain syndromes in patients with multiple sclerosis]

Among the numerous pain syndromes (PS) of various localizations and types, observed in patients with multiple sclerosis (MS), the greatest attention of researchers is attracted by neuropathic PS. Neuropathic PS are often present already in the early stage of MS, significantly reduce the quality of life, hinder the social adaptation of patients, poorly respond to therapy. Central neuropathic PS, which pathogenesis is closely related with plaques in the central nervous system, are most common in patients with MS. Diagnostics of neuropathic PS in MS is based mainly on typical clinical symptoms; MRI and neurophysiological methods data are of secondary importance. This review focuses on modern concepts of three main neuropathic PS in MS: ongoing extremity pain, trigeminal neuralgia and Lhermitte's sign. Clinical symptoms of neuropathic PS, current ideas about their pathogenetic mechanisms, MRI and neurophysiological techniques data and the existing approaches to conservative therapy and surgical treatment based on randomized trials data are presented.

Pharmacological treatment of central neuropathic pain: consensus of the Brazilian Academy of Neurology

ABSTRACT Background: Central neuropathic pain (CNP) is often refractory to available therapeutic strategies and there are few evidence-based treatment options. Many patients with neuropathic pain are not diagnosed or treated properly. Thus, consensus-based recommendations, adapted to the available drugs in the country, are necessary to guide clinical decisions. Objective: To develop recommendations for the treatment of CNP in Brazil. Methods: Systematic review, meta-analysis, and specialists opinions considering efficacy, adverse events profile, cost, and drug availability in public health. Results: Forty-four studies on CNP treatment were found, 20 were included in the qualitative analysis, and 15 in the quantitative analysis. Medications were classified as first-, second-, and third-line treatment based on systematic review, meta-analysis, and expert opinion. As first-line treatment, gabapentin, duloxetine, and tricyclic antidepressants were included. As second-line, venlafaxine, pregabalin for CND secondary to spinal cord injury, lamotrigine for CNP after stroke, and, in association with first-line drugs, weak opioids, in particular tramadol. For refractory patients, strong opioids (methadone and oxycodone), cannabidiol/delta-9-tetrahydrocannabinol, were classified as third-line of treatment, in combination with first or second-line drugs and, for central nervous system (CNS) in multiple sclerosis, dronabinol. Conclusions: Studies that address the treatment of CNS are scarce and heterogeneous, and a significant part of the recommendations is based on experts opinions. The CNP approach must be individualized, taking into account the availability of medication, the profile of adverse effects, including addiction risk, and patients' comorbidities.

Pharmacotherapeutic Options for Managing Pain in Multiple Sclerosis

Pain is a major matter for patients with multiple sclerosis; treatment response is frequently inadequate, with a significant impact on quality of life. The estimated prevalence of pain in multiple sclerosis ranges widely (26-86%), and different subtypes of pain, mediated by specific pathophysiological mechanisms, are described. The aim of this narrative review, performed using a systematic search methodology, was to provide current, evidence-based, knowledge about the pharmacological treatment of the different kinds of pain in multiple sclerosis. We searched for relevant papers within PubMed, EMBASE, the Cochrane Database of Systematic Reviews, and the Clinical Trials database (ClinicalTrials.gov), considering publications up to November 2019. Two authors independently selected studies for inclusion, data extraction, and bias assessment. A total of 27 randomized controlled trials were identified, but in only a few cases, patients with different pain qualities were stratified. Following a mechanism-based approach, treatment of paroxysmal pain and painful tonic spasms should be based on sodium-channel blockers, whereas treatment of ongoing extremity pain should be based on gabapentinoids and antidepressants.

Brivaracetam attenuates pain behaviors in a murine model of neuropathic pain

Background

The antiseizure racetams may provide novel molecular insights into neuropathic pain due to their unique mechanism involving synaptic vesicle glycoprotein 2A. Anti-allodynic effects of levetiracetam have been shown in animal models of neuropathic pain. Here, we studied the effect of brivaracetam, which binds to synaptic vesicle glycoprotein 2A with 20-fold greater affinity, and has fewer off-target effects.

Methods

Mice underwent unilateral sciatic nerve cuffing and were evaluated for mechanical sensitivity using von Frey filaments. Pain behaviors were assessed with prophylactic treatment using levetiracetam (100 or 10 mg/kg) or brivaracetam (10 or 1 mg/kg) beginning after surgery and continuing for 21 days, or with therapeutic treatment using brivaracetam (10 or 1 mg/kg) beginning on day 14, after allodynia was established, and continuing for 28 or 63 days. Spinal cord tissues from the prophylaxis experiment with10 mg/kg brivaracetam were examined for neuroinflammation (Iba1 and tumor necrosis factor), T-lymphocyte (CD3) infiltration, and synaptic vesicle glycoprotein 2A expression.

Results

When used prophylactically, levetiracetam, 100 mg/kg, and brivaracetam, 10 mg/kg, prevented the development of allodynia, with lower doses of each being less effective. When used therapeutically, brivaracetam extinguished allodynia, requiring 10 days with 10 mg/kg, and six weeks with 1 mg/kg. Brivaracetam was associated with reduced neuroinflammation and reduced T-lymphocyte infiltration in the dorsal horn. After sciatic nerve cuffing, synaptic vesicle glycoprotein 2A expression was identified in neurons, activated astrocytes, microglia/macrophages, and T lymphocytes in the dorsal horn.

Conclusion

Synaptic vesicle glycoprotein 2A may represent a novel target for neuropathic pain. Brivaracetam may warrant study in humans with neuropathic pain due to peripheral nerve injury.

Review of Treatment for Central Spinal Neuropathic Pain and Its Effect on Quality of Life: Implications for Neuromyelitis Optica Spectrum Disorder

OBJECTIVES

Neuromyelitis optica spectrum disorder (NMOSD) causes disabling and persistent central neuropathic pain (NP). Because the pain syndrome in NMOSD is severe and often intractable to analgesic treatment, it interferes with quality of life in patients. No interventional trials have been published looking at response to interventions for pain in NMOSD. This is a synthesis of the literature surveying the impact on quality of life of interventions in all mechanisms of central spinal NP. This review has important implications for management of pain in NMOSD.

METHODS AND DATA SOURCES

A systematic database search was conducted using PubMed, Embase, and CINAHL Plus with keywords including "spinal cord," "quality of life," and "neuropathic pain" in an attempt to identify original research that targeted spinal NP treatment and used quality of life as an outcome measure. Both pharmacologic and nonpharmacologic treatments were sought out.

RESULTS

Twenty-one studies meeting our eligibility criteria were identified and evaluated, 13 using pharmacologic treatments and 8 using nonpharmacologic interventions. Overall, sample sizes were modest, and effects on decreasing pain and/or improving quality of life were suboptimal.

CONCLUSIONS

This review provides researchers with a foundation from which to start a more thorough and thoughtful investigation into the management of NP in NMOSD and underscores the importance of including quality of life as a clinically meaningful outcome measure.

Non-pharmacological interventions for chronic pain in multiple sclerosis

BACKGROUND

Chronic pain is common and significantly impacts on the lives of persons with multiple sclerosis (pwMS). Various types of non-pharmacological interventions are widely used, both in hospital and ambulatory/mobility settings to improve pain control in pwMS, but the effectiveness and safety of many non-pharmacological modalities is still unknown.

OBJECTIVES

This review aimed to investigate the effectiveness and safety of non-pharmacological therapies for the management of chronic pain in pwMS. Specific questions to be addressed by this review include the following.Are non-pharmacological interventions (unidisciplinary and/or multidisciplinary rehabilitation) effective in reducing chronic pain in pwMS?What type of non-pharmacological interventions (unidisciplinary and/or multidisciplinary rehabilitation) are effective (least and most effective) and in what setting, in reducing chronic pain in pwMS?

SEARCH METHODS

A literature search was performed using the specialised register of the Cochrane MS and Rare Diseases of the Central Nervous System Review Group, using the Cochrane MS Group Trials Register which contains CENTRAL, MEDLINE, Embase, CINAHL, LILACUS, Clinical trials.gov and the World Health Organization International Clinical Trials Registry Platform on 10 December 2017. Handsearching of relevant journals and screening of reference lists of relevant studies was carried out.

SELECTION CRITERIA

All published randomised controlled trials (RCTs)and cross-over studies that compared non-pharmacological therapies with a control intervention for managing chronic pain in pwMS were included. Clinical controlled trials (CCTs) were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

All three review authors independently selected studies, extracted data and assessed the methodological quality of the studies using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) tool for best-evidence synthesis. Pooling data for meta-analysis was not possible due to methodological, clinical and statistically heterogeneity of the included studies.

MAIN RESULTS

Overall, 10 RCTs with 565 participants which investigated different non-pharmacological interventions for the management of chronic pain in MS fulfilled the review inclusion criteria. The non-pharmacological interventions evaluated included: transcutaneous electrical nerve stimulation (TENS), psychotherapy (telephone self-management, hypnosis and electroencephalogram (EEG) biofeedback), transcranial random noise stimulation (tRNS), transcranial direct stimulation (tDCS), hydrotherapy (Ai Chi) and reflexology.There is very low-level evidence for the use of non-pharmacological interventions for chronic pain such as TENS, Ai Chi, tDCS, tRNS, telephone-delivered self-management program, EEG biofeedback and reflexology in pain intensity in pwMS. Although there were improved changes in pain scores and secondary outcomes (such as fatigue, psychological symptoms, spasm in some interventions), these were limited by methodological biases within the studies.

AUTHORS' CONCLUSIONS

Despite the use of a wide range of non-pharmacological interventions for the treatment of chronic pain in pwMS, the evidence for these interventions is still limited or insufficient, or both. More studies with robust methodology and greater numbers of participants are needed to justify the effect of these interventions for the management of chronic pain in pwMS.

Levetiracetam synergises with common analgesics in producing antinociception in a mouse model of painful diabetic neuropathy

Painful diabetic neuropathy is difficult to treat. Single analgesics often have insufficient efficacy and poor tolerability. Combination therapy may therefore be of particular benefit, because it might provide optimal analgesia with fewer adverse effects. This study aimed to examine the type of interaction between levetiracetam, a novel anticonvulsant with analgesic properties, and commonly used analgesics (ibuprofen, aspirin and paracetamol) in a mouse model of painful diabetic neuropathy. Diabetes was induced in C57BL/6 mice with a single high dose of streptozotocin, applied intraperitoneally (150 mg/kg). Thermal (tail-flick test) and mechanical (electronic von Frey test) nociceptive thresholds were measured before and three weeks after diabetes induction. The antinociceptive effects of orally administered levetiracetam, analgesics, and their combinations were examined in diabetic mice that developed thermal/mechanical hypersensitivity. In combination experiments, the drugs were co-administered in fixed-dose fractions of single drug ED50 and the type of interaction was determined by isobolographic analysis. Levetiracetam (10-100 mg/kg), ibuprofen (2-50 mg/kg), aspirin (5-75 mg/kg), paracetamol (5-100 mg/kg), and levetiracetam-analgesic combinations produced significant, dose-dependent antinociceptive effects in diabetic mice in both tests. In the tail-flick test, isobolographic analysis revealed 15-, and 19-fold reduction of doses of both drugs in the combination of levetiracetam with aspirin/ibuprofen, and paracetamol, respectively. In the von Frey test, approximately 7- and 9-fold reduction of doses of both drugs was detected in levetiracetam-ibuprofen and levetiracetam-aspirin/levetiracetam-paracetamol combinations, respectively. These results show synergism between levetiracetam and ibuprofen/aspirin/paracetamol in a model of painful diabetic neuropathy and might provide a useful approach to the treatment of patients suffering from painful diabetic neuropathy.

Pharmacological treatment of chronic non-cancer pain in pediatric patients

Chronic pain in children and young adults occurs frequently and contributes to early disability as well as personal and familial distress. A biopsychosocial approach to evaluation and treatment is recommended. Within this approach, there is a role for pharmacologic intervention. A variety of medications are used for chronic pain conditions in pediatric patients. Medication classes include anticonvulsants, muscle relaxants, antidepressants, opioids, local anesthetics, and anti-inflammatory drugs. Data is sparse, and most medications are used without condition-specific approval by national regulatory agencies such as the Food and Drug Administration in the US and the European Medicines Agency. In the absence of evidence on which to base practice, optimal drug therapy decisions rest on understanding proposed mechanisms of pain conditions, extrapolation from adult data-when such exists, and empirical and experiential knowledge. Drug delivery systems have evolved, and practitioners have to decide amongst not only medication classes, but also routes of delivery. Opioids are not recommended for use by non-pain specialists for the treatment of pediatric chronic pain, and even then the issues are more complex than can be addressed here. This article reviews the major medications used for pediatric chronic pain conditions.

Levetiracetam for neuropathic pain in adults

BACKGROUND

Antiepileptic drugs have been used in pain management since the 1960s; some have shown efficacy in treating different neuropathic pain conditions. The efficacy of levetiracetam for relief of neuropathic pain has not previously been reviewed.

OBJECTIVES

To assess the analgesic efficacy and adverse events of levetiracetam in chronic neuropathic pain conditions in adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2014, Issue 6) (via the Cochrane Library), MEDLINE, EMBASE, and two clinical trials databases (ClinicalTrials.gov. and the World Health Organisation Clinical Trials Registry Platform) to 3 July 2014, together with reference lists of retrieved papers and reviews.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks duration or longer, comparing levetiracetam with placebo or another active treatment in adults with chronic neuropathic pain conditions. Studies had to have a minimum of 10 participants per treatments arm.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted efficacy and adverse event data, and examined issues of study quality. We performed analysis using three tiers of evidence. First tier evidence derived from data meeting current best standards and subject to minimal risk of bias (outcome equivalent to substantial pain intensity reduction; intention-to-treat analysis without imputation for dropouts; at least 200 participants in the comparison; 8 to 12 weeks duration; parallel design); second tier evidence from data that failed to meet one or more of these criteria and that we considered at some risk of bias but with at least 200 participants in the comparison; and third tier evidence from data involving fewer than 200 participants that was considered very likely to be biased or used outcomes of limited clinical utility, or both.

MAIN RESULTS

We included six studies: five small, cross-over studies with 174 participants, and one parallel group study with 170 participants. Participants were treated with levetiracetam (2000 mg to 3000 mg daily) or placebo for between four and 14 weeks. Each study included participants with a different type of neuropathic pain; central pain due to multiple sclerosis, pain following spinal cord injury, painful polyneuropathy, central post-stroke pain, postherpetic neuralgia, and post-mastectomy pain.None of the included studies provided first or second tier evidence. The evidence was very low quality, downgraded because of the small size of the treatment arms, and because studies reported results using last observation carried forward (LOCF) imputation for withdrawals or using only participants who completed the study according to the protocol, where there were greater than 10% withdrawals. There were insufficient data for a pooled efficacy analysis in particular neuropathic pain conditions, but individual studies did not show any analgesic effect of levetiracetam compared with placebo. We did pool results for any outcome considered substantial pain relief (≥ 50% pain intensity reduction or 'complete' or 'good' responses on the verbal rating scale) for four studies with dichotomous data; response rates across different types of neuropathic pain was similar with levetiracetam (10%) and placebo (12%), with no statistical difference (risk ratio 0.9; 95% confidence interval (CI) 0.4 to1.7).We pooled data across different conditions for adverse events and withdrawals. Based on very limited data, significantly more participants experienced an adverse event with levetiracetam than with placebo (number needed to treat for an additional harmful event (NNH) 8.0 (95% CI 4.6 to 32)). There were significantly more adverse event withdrawals with levetiracetam (NNH 9.7 (6.7 to 18)).

AUTHORS' CONCLUSIONS

The amount of evidence for levetiracetam in neuropathic pain conditions was very small and potentially biased because of the methods of analysis used in the studies. There was no indication that levetiracetam was effective in reducing neuropathic pain, but it was associated with an increase in participants who experienced adverse events and who withdrew due to adverse events.

Systematic review and meta-analysis of pharmacological therapies for pain associated with postherpetic neuralgia and less common neuropathic conditions

OBJECTIVE

To estimate the relative efficacy of pharmacological therapies for the treatment of postherpetic neuralgia (PHN), multiple sclerosis (MS)-related pain, posttraumatic pain, central poststroke pain (CPSP) and human immunodeficiency virus (HIV)-related neuropathic pain (NeP).

METHODS

This systematic review (through June 2011) identified randomised, controlled trials of treatments for these conditions. Bayesian mixed treatment comparison (MTC) methods were used to determine the relative efficacy and safety among the treatments within each pain condition.

RESULTS

Fifty studies were identified: 33 PHN, 2 MS-related pain, 3 CPSP, 3 posttraumatic pain and 9 HIV-related NeP. Data from 28 PHN studies including 21 interventions and 4317 patients were included into the PHN MTC. Of treatments studied in ≥ 50 patients, opioids had the greatest mean pain reduction of -1.70 vs. placebo on an 11-point numeric rating scale. Pregabalin ≥ 300 mg/day was most effective for ≥ 30% and ≥ 50% pain reduction [relative risk (RR) vs. placebo = 2.44 and 2.13, respectively]. Data identified for MS-related pain, CPSP, posttraumatic pain and HIV-related NeP were sparse; only 7 of 17 studies had ≥ 50 patients. Adverse events (AEs) and discontinuations for most treatments were not significantly greater than placebo except in PHN, where 8 of 12 treatments had higher risks of AEs compared with placebo and tricyclic antidepressants and opioids had higher risk of discontinuation compared with placebo.

CONCLUSIONS

Guideline-recommended treatments for PHN were more effective than placebo on the pain NRS and for ≥ 30% and ≥ 50% pain reduction. Although guidelines exist for the management of less common NeP conditions, little published evidence supports them. These results highlight the need for additional evaluations and more complete reporting of outcomes to help guide physicians' treatment selections.

Mechanisms and pharmacology of neuropathic pain in multiple sclerosis

The neuropathic pain of multiple sclerosis is quite prevalent and severely impacts quality of life. A few randomized, placebo-controlled, blinded clinical trials suggest that cannabis- and anticonvulsant-based treatments provide partial pain relief, but at the expense of adverse events. An even smaller, but emerging, number of translational studies are using rodent models of experimental autoimmune encephalomyelitis (EAE), which exhibit pain-like behaviors resembling those of Multiple sclerosis (MS) patients. These studies not only support the possible effectiveness of anticonvulsants, but also compel further clinical trials with serotonin-norepinephrine reuptake inhibitors, the immunosuppressant drug rapamycin, or drugs which interfere with glutamatergic neurotransmission. Future behavioral studies in EAE models are essential toward a new pharmacotherapy of multiple sclerosis pain.

Multiple sclerosis-induced neuropathic pain: pharmacological management and pathophysiological insights from rodent EAE models

In patients with multiple sclerosis (MS), pain is a frequent and disabling symptom. The prevalence is in the range 29-86 % depending upon the assessment protocols utilised and the definition of pain applied. Neuropathic pain that develops secondary to demyelination, neuroinflammation and axonal damage in the central nervous system is the most distressing and difficult type of pain to treat. Although dysaesthetic extremity pain, L'hermitte's sign and trigeminal neuralgia are the most common neuropathic pain conditions reported by patients with MS, research directed at gaining insight into the complex mechanisms underpinning the pathobiology of MS-associated neuropathic pain is in its relative infancy. By contrast, there is a wealth of knowledge on the neurobiology of neuropathic pain induced by peripheral nerve injury. To date, the majority of research in the MS field has used rodent models of experimental autoimmune encephalomyelitis (EAE) as these models have many clinical and neuropathological features in common with those observed in patients with MS. However, it is only relatively recently that EAE-rodents have been utilised to investigate the mechanisms contributing to the development and maintenance of MS-associated central neuropathic pain. Importantly, EAE-rodent models exhibit pro-nociceptive behaviours predominantly in the lower extremities (tail and hindlimbs) as seen clinically in patients with MS-neuropathic pain. Herein, we review research to date on the pathophysiological mechanisms underpinning MS-associated neuropathic pain as well as the pharmacological management of this condition. We also identify knowledge gaps to guide future research in this important field.

Symptomatic treatment and management of multiple sclerosis

The range of symptoms which occur in multiple sclerosis (MS) can have disabling functional consequences for patients and lead to significant reductions in their quality of life. MS symptoms can also interact with each other, making their management challenging. Clinical trials aimed at identifying symptomatic therapies have generally been poorly designed and have tended to be underpowered. Therefore, the evidence base for the management of MS symptoms with pharmacologic therapies is not strong and tends to rely upon open-label studies, case reports, and clinical trials with small numbers of patients and poorly validated clinical outcome measures. Recently, there has been a growing interest in the management of MS symptoms with pharmacologic treatments, and better-designed, randomized, double-blind, controlled trials have been reported. This chapter will describe the evidence base predominantly behind the various pharmacologic approaches to the management of MS symptoms, which in most, if not all, cases, requires multidisciplinary input. Drugs routinely recommended for individual symptoms and new therapies, which are currently in the development pipeline, will be reviewed. More interventional therapies related to symptoms that are refractory to pharmacotherapy will also be discussed, where relevant.

An observational trial to investigate the efficacy and tolerability of levetiracetam in trigeminal neuralgia

OBJECTIVE

To explore the efficacy and tolerability of levetiracetam in medical treatment of trigeminal neuralgia.

BACKGROUND

Antiepileptic drugs (AEDs) are considered as first-line treatment for trigeminal neuralgia, although their use is often limited due to incomplete efficacy and tolerability. Newer AEDs with improved safety profile may be useful in this disorder.

METHODS

Patients suffering from trigeminal neuralgia (either primary or secondary) refractory to previous treatments were recruited to be treated with levetiracetam (3-4 g/day) for 16 weeks as add-on therapy, after a 2-week baseline period. Rescue medication was allowed in both the baseline and treatment phases. The primary efficacy measure was the number of attacks per day. The patients' efficacy evaluation, the patients' global evaluation for both safety and efficacy, changes in the Hamilton Depression Scale, the Hamilton Anxiety Scale, and the Quality of Life Measure Short Form-36 were secondary parameters.

RESULTS

Twenty-three patients were included in the analysis. After treatment and compared to the baseline phase, the number of daily attacks decreased by 62.4%. All secondary parameters changed significantly with the exception of the Quality of Life Measure Short Form-36 score. Seven patients withdrew from the study. Five patients (21.7%) reported side effects and 2 withdrew.

CONCLUSIONS

Levetiracetam may be effective and safe in trigeminal neuralgia treatment. Confirmation in a randomized controlled study is needed.

Neurovascular unit in chronic pain

Chronic pain is a debilitating condition with major socioeconomic impact, whose neurobiological basis is still not clear. An involvement of the neurovascular unit (NVU) has been recently proposed. In particular, the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB), two NVU key players, may be affected during the development of chronic pain; in particular, transient permeabilization of the barrier is suggested by several inflammatory- and nerve-injury-based pain models, and we argue that the clarification of molecular BBB/BSCB permeabilization events will shed new light in understanding chronic pain mechanisms. Possible biases in experiments supporting this theory and its translational potentials are discussed. Moving beyond an exclusive focus on the role of the endothelium, we propose that our understanding of the mechanisms subserving chronic pain will benefit from the extension of research efforts to the NVU as a whole. In this view, the available evidence on the interaction between analgesic drugs and the NVU is here reviewed. Chronic pain comorbidities, such as neuroinflammatory and neurodegenerative diseases, are also discussed in view of NVU changes, together with innovative pharmacological solutions targeting NVU components in chronic pain treatment.

A mechanism-based classification of pain in multiple sclerosis

Pharmacological treatment of pain in multiple sclerosis (MS) is challenging due to the many underlying pathophysiological mechanisms. Few controlled trials show adequate pain control in this population. Emerging evidence suggests that pain might be more effectively classified and treated according to symptoms and underlying mechanisms. The new mechanism-based classification we propose here distinguishes nine types of MS-related pain: trigeminal neuralgia and Lhermitte's phenomenon (paroxysmal neuropathic pain due to ectopic impulse generation along primary afferents), ongoing extremity pain (deafferentation pain secondary to lesion in the spino-thalamo-cortical pathways), painful tonic spasms and spasticity pain (mixed pains secondary to lesions in the central motor pathways but mediated by muscle nociceptors), pain associated with optic neuritis (nerve trunk pain originating from nervi nervorum), musculoskeletal pains (nociceptive pain arising from postural abnormalities secondary to motor disorders), migraine (nociceptive pain favored by predisposing factors or secondary to midbrain lesions), and treatment-induced pains. Identification of various types of MS-related pain will allow appropriate targeted pharmacological treatment and improve clinical practice.

The effects of clinical interventions on health-related quality of life in multiple sclerosis: a meta-analysis

The objective is to estimate the extent to which existing health care interventions designed specifically to target health-related quality of life (HRQL) in persons with multiple sclerosis (MS) achieve this aim. The structured literature search was conducted using multiple electronic databases including Ovid MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature and the Cochrane Central Register of Controlled Trial, for the years 1960 to 2011. The methodological quality of selected randomized controlled trials (RCTs) was assessed using the Cochrane Collaboration's recommended domain-based method. Effect size (ES) was used to measure the effect of each intervention on HRQL. The studies were combined using a random-effects model to account for inter-study variation. Heterogeneity was tested for using the I-test and publication bias was assessed using funnel plots and the Egger weighted regression statistic. Thirty-nine RCTs met the criteria, all with acceptable methodological quality. Six major types of interventions were identified through the search. The smallest effect was observed for self-management and complementary and alternative medicine (ES=0.2), followed by medication (ES=0.3) then cognitive training and exercise (ES=0.4), and psychological interventions to improve mood (ES=0.7). The magnitude of positive effect on HRQL varied between the different types of interventions. The extent to which interventions are able to improve HRQL depends on delivering a potent intervention to those persons who have the potential to benefit.

Treating pain in multiple sclerosis

INTRODUCTION

Multiple sclerosis (MS) is an inflammatory, demyelinating, central nervous system disease that frequently causes pain.

AREAS COVERED

This article reviews the current literature and describes the therapeutic options for treating MS-related pain. The reader will be provided with current, evidence-based knowledge about the treatment of MS-related pain, and the review will take a practical approach to the various drugs for treating pain, including starting dose, titration and side effects.

EXPERT OPINION

Only cannabinoids have been assessed in randomized, controlled trials. Because of the concern regarding the risk of abuse and psychiatric adverse events, published guidelines as well as expert recommendations suggest using them as second-line therapy only. Hence, current treatment should be based on the general principles for treating peripheral neuropathic pain, taking into account drug-induced adverse effects.

Medication Repurposing: New Uses for Old Drugs

Background:

Medication repurposing, the practice of using old drugs in new ways, is becoming more common. Old drugs that had previously fallen out of favor due to safety concerns, lack of efficacy, or development of more desirable therapeutic alternatives have been resurfacing in the literature and on pharmacy shelves. Developing new uses for old drugs may provide patients with access to helpful therapies but may also present challenges and risks.

Objective:

To explore the rationale for, and historical context of, the developing trend of recycling existing drugs for new, innovative uses, and to provide pharmacy practitioners with information about how to find clinical evidence regarding these new uses.

Data Synthesis:

The process of obtaining marketing approval for new drugs can take an average of over 10 years and exceed $1 billion. Repurposing old drugs (both approved and unapproved) for new uses requires considerably fewer resources since information about production needs, pharmacology, and pharmacokinetics is already known. Other advantages of using old drugs include faster availability for patient use and known safety concerns for the original indication. Disadvantages of new uses for old drugs may include lack of clinical evidence, unknown safety for the new clinical context, limited availability of information about new uses, and liability or legal concerns. Several methods of identifying potential new uses exist, including the observance of previously unknown desirable pharmacologic effects during clinical use, new knowledge of a mechanism of action leading to exploration of innovative therapeutic areas, or screening compound libraries for targeted clinical activity.

Conclusions:

There are many examples of recycling existing medications for new purposes. Pharmacy practitioners should be aware of this developing trend and know how to find information about utilizing old drugs in new ways.

Role of cannabinoids in multiple sclerosis

Although extracts from the cannabis plant have been used medicinally for thousands of years, it is only within the last 2 decades that our understanding of cannabinoid physiology and the provision of evidence for therapeutic benefit of cannabinoids has begun to accumulate. This review provides a background to advances in our understanding of cannabinoid receptors and the endocannabinoid system, and then considers how cannabinoids may help in the management of multiple sclerosis (MS). The relative paucity of treatments for MS-related symptoms has led to experimentation by patients with MS in a number of areas including the use of cannabis extracts. An increasing amount of evidence is now emerging to confirm anecdotal reports of symptomatic improvement, particularly for muscle stiffness and spasms, neuropathic pain and sleep and bladder disturbance, in patients with MS treated with cannabinoids. Trials evaluating a role in treating other symptoms such as tremor and nystagmus have not demonstrated any beneficial effects of cannabinoids. Safety profiles of cannabinoids seem acceptable, although a slow prolonged period of titration improves tolerability. No serious safety concerns have emerged. Methodological issues in trial design and treatment delivery are now being addressed. In addition, recent experimental evidence is beginning to suggest an effect of cannabinoids on more fundamental processes important in MS, with evidence of anti-inflammation, encouragement of remyelination and neuroprotection. Trials are currently under way to test whether cannabinoids may have a longer term role in reducing disability and progression in MS, in addition to symptom amelioration, where indications are being established.

Painful and involuntary multiple sclerosis

INTRODUCTION

Pain, dysphagia, respiratory problems, sexual and cardiovascular dysfunctions may occur in patients with MS.

AREAS COVERED

In the present review, we attempt to summarize the current knowledge on the impact pain, dysphagia, respiratory problems, sexual and cardiovascular dysfunctions have in patients with MS.

EXPERT OPINION

To effectively manage MS, it is essential that these symptoms are recognized as early as possible and treated by a rehabilitative multidisciplinary approach, based on proven scientific evidence.

Pharmacological management of pain in patients with multiple sclerosis

Multiple sclerosis (MS) is an inflammatory, demyelinating, autoimmune disease of the CNS. There are currently a number of disease-modifying medications for MS that modulate or suppress the immune system; however, these medications do not directly relieve MS symptoms, which include visual deficits, gait problems, sensory deficits, weakness, tremor, spasticity and pain, among others. Pain is a common symptom in MS which has recently been estimated to be experienced by more than 40% of patients. Nociceptive pain occurs as an appropriate physiological response transmitted to a conscious level when nociceptors in bone, muscle or any body tissue are activated, warning the organism of tissue damage. Neuropathic pain is initiated as a direct consequence of a lesion or disease affecting the somatosensory system, with no physiological advantage. Nociceptive and neuropathic pain in MS may be present concurrently and at different stages of the disease, and may be associated with other symptoms. Central neuropathic pain has been reported to be among the most common pain syndromes in MS. It is described as constant, often spontaneous, burning occurring more frequently in the lower limbs. Treatment typically includes tricyclic antidepressants and antiepileptic medications, although studies have been conducted in relatively small samples and optimal dosing has not been confirmed. Cannabinoids have been among the few treatments studied in well designed, randomized, placebo-controlled trials for central neuropathic pain. In the largest of these trials, which included 630 subjects, a 15-week comparison between Delta9-tetrahydrocannabinol and placebo was performed. More patients receiving active treatment perceived an improvement in pain than those receiving placebo, although approximately 20% of subjects reported worsening of pain while on active treatment. Trigeminal neuralgia, while affecting less than 5% of patients with MS, is the most studied pain syndrome. The pain can be extreme and is typically treated with carbamazepine, although adverse effects can mimic an MS exacerbation. Painful topic spasms occur in approximately 11% of the MS population and are treated with antispasticity medications such as baclofen and benzodiazepines. Gabapentin has also demonstrated efficacy, but all studies have included small sample sizes. In general, evidence for treating pain in MS is limited. Many clinical features of pain are often unrecognized by clinicians and are difficult for patients to describe. Treatment is often based on anecdotal reports and clinical experience. We present a review of treatment options for pain in MS, which should serve to update current knowledge, highlight shortcomings in clinical research and provide indications towards achieving evidence-based treatment of pain in MS.

Analysis of the pain in multiple sclerosis patients

INTRODUCTION

Despite pain being a disabling symptom in patients with multiple sclerosis (MS), its prevalence and characteristics are not well established. The aim of this study is to describe the characteristics and prevalence of pain in patients with MS, and to assess the associated clinical variables and radiological findings.

METHODS

We prospectively studied patients with MS. A structured questionnaire which evaluated depression symptoms, type of pain, location, intensity (defined according to a visual analogue scale (VAS) as severe (VAS 7-10), moderate (VAS 4-6) and mild (VAS 0-4), and pain therapy was recorded in patients who referred to pain at the time of interview. Protocol variables were demographic data, MS clinical forms (remitting-relapsing, progressive-secondary and progressive-primary), neurological dysfunction (defined according to EDSS scale), symptoms at onset, attack frequency, illness duration, disease modifying treatment, fatigue, spasticity, oligoclonal bands in CSF, visual evoked potentials, depression symptoms (Hamilton test) and presence of lesions in spinal cord MRI.

RESULTS

A total of 134 MS patients were included, and MRI was performed on 105 of them. Pain was reported by 74 (55%) patients and was most frequently neuropathic, located in limbs, severe and burning/spiky. Of these 28 (38%) received therapy for their pain, based predominantly in anti-inflammatory drugs. Patients with pain had a worse functional state (EDSS score, 4.5 [3-6] vs 1.5 [1-2], p<0.001), higher number of relapses (7.13±3.4 vs 3.75±2.9, p<0.001), progressive forms of MS (86.7% vs 13.3%, p<0.001), depression (91.9% vs 8.1%, p<0.001), spinal cord involvement at onset (79.2% vs 20.8%, p=0.009), spinal cord lesions by MRI (84.3% vs 15.7%, p<0.001) and longer duration of disease (14.6±7.8 vs 8.43±5.9 months, p<0.001). In a logistic regression model, the presence of lesions in spinal cord MRI (OR 3.5 [1.5-24.5]) and higher EDSS score (OR 1.7 [1.1-2.7]) were independently associated with pain.

CONCLUSIONS

Pain is a frequent disabling symptom in MS and is associated with disability and spinal cord lesions.

Multiple sclerosis-related central pain disorders

Central neuropathic pain is common in multiple sclerosis (MS), and its prevalence increases with physical disability. Sufficient evidence links dysesthetic pain, trigeminal neuralgia, Lhermitte's sign, and painful tonics spasms to plaque formation in the spinal cord and brain, whereas the association with headache and back pain remains unclear. Management varies according to the pain in question. For dysesthetic pain, drugs in use for neuropathic pain in general are recommended as first-line treatment, and emerging evidence suggests some benefit from cannabinoids and levetiracetam. Because of unique characteristics of MS-related trigeminal neuralgia, ganglion and root level neuroablative procedures are worth considering before microvascular decompression. Overall, the lack of controlled clinical trials, together with our limited understanding of the pathophysiological mechanisms involved, form a hindrance to a systematic and rational management of MS-related pain.

The antihyperalgesic effect of levetiracetam in an inflammatory model of pain in rats: mechanism of action

BACKGROUND AND PURPOSE

Levetiracetam, a novel antiepileptic drug, has recently been shown to have antinociceptive effects in various animal models of pain. The purpose of this study was to investigate the antihyperalgesic effect of levetiracetam and its mechanism of action, by examining the involvement of GABAergic, opioidergic, 5-hydroxytryptaminergic (5-HTergic) and adrenergic systems in its effect, in a rat model of inflammatory pain.

EXPERIMENTAL APPROACH

Rats were intraplantarly injected with the pro-inflammatory compound carrageenan. A paw pressure test was used to determine: (i) the effect of levetiracetam on carrageenan-induced hyperalgesia; and (ii) the effects of bicuculline (selective GABA(A) receptor antagonist), naloxone (non-selective opioid receptor antagonist), methysergide (non-selective 5-HT receptor antagonist) and yohimbine (selective alpha(2)-adrenoceptor antagonist) on the antihyperalgesic action of levetiracetam.

RESULTS

Levetiracetam (10-200 mg.kg(-1); p.o.) significantly reduced, in a dose-dependent manner, the inflammatory hyperalgesia induced by carrageenan. The antihyperalgesic effect of levetiracetam was significantly decreased after administration of bicuculline (0.5-2 mg.kg(-1); i.p.), naloxone (1-3 mg.kg(-1); i.p.), methysergide (0.25-1 mg.kg(-1); i.p.) and yohimbine (1-3 mg.kg(-1); i.p.).

CONCLUSIONS AND IMPLICATIONS

These results show that levetiracetam produced antihyperalgesia which is at least in part mediated by GABA(A), opioid, 5-HT and alpha(2)-adrenergic receptors, in an inflammatory model of pain. The efficacy of levetiracetam in this animal model of inflammatory pain suggests that it could be a potentially important agent for treating inflammatory pain conditions in humans.

Update on anticonvulsant drugs

In 2009, the US Food and Drug Administration approved three medications for the treatment of epilepsy: rufinamide, lacosamide, and vigabatrin. In addition, extended-release formulations of lamotrigine and levetiracetam were approved recently. When added to the dozen medications for treating epilepsy, the choice is a luxury in terms of additional options, but also a challenge for practitioners to use them all with expertise. Recently, there has been much interest surrounding medications for epilepsy and their possible association with osteoporosis, safety during pregnancy, biological equivalence to generic versions, and possible association with higher rates of suicidality. This review discusses these issues and provides a current overview for the medical management of epilepsy.