Persistent headache and low back pain after accidental dural puncture in the obstetric population: a prospective, observational, multicentre cohort study.

Accidental dural puncture following epidural insertion can cause a post-dural headache that is defined by the International Headache Society as self-limiting. We aimed to confirm if accidental dural puncture could be associated with persistent headache and back pain when compared with matched control parturients. We performed a prospective multicentre cohort study evaluating the incidence of persistent headache following accidental dural puncture at nine UK obstetric units. Parturients who sustained an accidental dural puncture were matched with controls who had undergone an uneventful epidural insertion. Participants were followed-up at six-monthly intervals for 18 months. Primary outcome was the incidence of persistent headache at 18 months. Ninety parturients who had an accidental dural puncture were matched with 180 controls. The complete dataset for primary analysis was available for 256 (95%) participants. Incidence of persistent headache at 18 months was 58.4% (52/89) in the accidental puncture group and 17.4% (29/167) in the control group, odds ratio (95%CI) 18.4 (6.0-56.7), p < 0.001, after adjustment for past history of headache, Hospital Anxiety and Depression Scale (depression) and Hospital Anxiety and Depression Scale (anxiety) scores. Incidence of low back pain at 18 months was 48.3% (43/89) in the accidental puncture group and 17.4% (29/167) in the control group, odds ratio (95%CI) 4.14 (2.11-8.13), with adjustment. We have demonstrated that accidental dural puncture is associated with long-term morbidity including persistent headache in parturients. This challenges the current definition of post-dural puncture headache as a self-limiting condition and raises possible clinical, financial and medicolegal consequences.

European Academy of Neurology guideline on trigeminal neuralgia.

BACKGROUND AND PURPOSE: Trigeminal neuralgia (TN) is an extremely painful condition which can be difficult to diagnose and treat. In Europe, TN patients are managed by many different specialities. Therefore, there is a great need for comprehensive European guidelines for the management of TN. The European Academy of Neurology asked an expert panel to develop recommendations for a series of questions that are essential for daily clinical management of patients with TN. METHODS: A systematic review of the literature was performed and recommendations was developed based on GRADE, where feasible; if not, a good practice statement was given. RESULTS: The use of the most recent classification system is recommended, which diagnoses TN as primary TN, either classical or idiopathic depending on the degree of neurovascular contact, or as secondary TN caused by pathology other than neurovascular contact. Magnetic resonance imaging (MRI), using a combination of three high-resolution sequences, should be performed as part of the work-up in TN patients, because no clinical characteristics can exclude secondary TN. If MRI is not possible, trigeminal reflexes can be used. Neurovascular contact plays an important role in primary TN, but demonstration of a neurovascular contact should not be used to confirm the diagnosis of TN. Rather, it may help to decide if and when a patient should be referred for microvascular decompression. In acute exacerbations of pain, intravenous infusion of fosphenytoin or lidocaine can be used. For long-term treatment, carbamazepine or oxcarbazepine are recommended as drugs of first choice. Lamotrigine, gabapentin, botulinum toxin type A, pregabalin, baclofen and phenytoin may be used either alone or as add-on therapy. It is recommended that patients should be offered surgery if pain is not sufficiently controlled medically or if medical treatment is poorly tolerated. Microvascular decompression is recommended as first-line surgery in patients with classical TN. No recommendation can be given for choice between any neuroablative treatments or between them and microvascular decompression in patients with idiopathic TN. Neuroablative treatments should be the preferred choice if MRI does not demonstrate any neurovascular contact. Treatment for patients with secondary TN should in general follow the same principles as for primary TN. In addition to medical and surgical management, it is recommended that patients are offered psychological and nursing support. CONCLUSIONS: Compared with previous TN guidelines, there are important changes regarding diagnosis and imaging. These allow better characterization of patients and help in decision making regarding the planning of medical and surgical management. Recommendations on pharmacological and surgical management have been updated. There is a great need for future research on all aspects of TN, including pathophysiology and management.

Altered theta oscillations in resting EEG of fibromyalgia syndrome patients.

BACKGROUND: Fibromyalgia syndrome (FM) is a chronic pain disorder characterized by widespread pain, sleep disturbance, fatigue and cognitive/affective symptoms. Functional imaging studies have revealed that FM and other chronic pain syndromes can affect resting brain activity. This study utilized electroencephalographic (EEG) recordings to investigate the relative power of ongoing oscillatory activity in the resting brain. METHODS: A 64-channel EEG was recorded at rest in 19 female FM patients and 18 healthy, age-matched, control subjects. The Manual Tender Point Scale (MTPS) examination was performed to quantify tonic pain and tenderness on the day of testing along with measures of mood, arousal and fatigue. Oscillations in delta, theta, alpha, beta and gamma frequency bands were analysed using Standardised Low-Resolution Brain Electromagnetic Tomography to evaluate sources of spectral activity throughout the whole brain. RESULTS: FM patients exhibited greater pain, tiredness and tension on the day of testing relative to healthy control participants and augmented theta activity in prefrontal and anterior cingulate cortices. No significant differences were seen in other frequency bands. Augmented frontal theta activity in FM patients significantly correlated with measures of tenderness and mean tiredness scores. CONCLUSIONS: The findings indicate that alterations to resting-state oscillatory activity may relate to ongoing tonic pain and fatigue in FM, and manifest in brain regions relevant for cognitive-attentional aspects of pain processing and endogenous pain inhibition. Enhanced low-frequency oscillations were previously seen in FM and other chronic pain syndromes, and may relate to pathophysiological mechanisms for ongoing pain such as thalamocortical dysrhythmia. SIGNIFICANCE: Increased prefrontal theta activity may contribute to persistent pain in fibromyalgia or represent the outcome of prolonged symptoms. The findings point to the potential for therapeutic interventions aimed at normalizing neural oscillations, while further research utilizing quantitative analysis of resting EEG could benefit our understanding of fibromyalgia pathophysiology.

Superiority of capsaicin 8% patch versus oral pregabalin on dynamic mechanical allodynia in patients with peripheral neuropathic pain.

BACKGROUND: Dynamic Mechanical Allodynia (DMA) is a typical symptom of neuropathic pain (NP). In a recent study, the capsaicin 8% patch was noninferior to pregabalin in overall peripheral NP relief. In this study, we report the comparison of the two treatments in relieving DMA. METHODS: In a randomized, open-label, head-to-head, 8-week study, 488 patients with peripheral NP were treated with the capsaicin 8% patch (one application) or an optimized dose of pregabalin. Assessments included the area and intensity of DMA, and the number of patients achieving complete resolution of DMA. RESULTS: At baseline, 253 patients in the capsaicin 8% patch group and 235 patients in the pregabalin group had DMA. From baseline to end of study, the change in DMA intensity was significantly in favour of the capsaicin 8% patch versus pregabalin [-0.63 (95% CI: -1.04, -0.23; p = 0.002)]. Similarly, the capsaicin 8% patch was superior to pregabalin in reducing the area of DMA [-39.5 cm2 (95% CI: -69.1, -10.0; p = 0.009)] from baseline to end of study. Overall, a greater proportion of patients had a complete resolution of allodynia with capsaicin 8% patch treatment compared with pregabalin treatment (24.1% vs. 12.3%; p = 0.001) at end of study. CONCLUSION: Capsaicin 8% treatment was superior to pregabalin in reducing the intensity and area of DMA, and in the number of patients with complete resolution of DMA. SIGNIFICANCE: The superiority of a topical treatment over pregabalin in relieving DMA supports the view that both peripheral and central sensitization can mediate allodynia.

Capsaicin 8% patch versus oral pregabalin in patients with peripheral neuropathic pain.

BACKGROUND: Clinical trials have not yet compared the efficacy of capsaicin 8% patch with current standard therapy in peripheral neuropathic pain (PNP). OBJECTIVES: Head-to-head efficacy and safety trial comparing the capsaicin patch with pregabalin in PNP. METHODS: Open-label, randomized, multicentre, non-inferiority trial. Patients with PNP, aged 18-80 years, were randomly assigned to either the capsaicin 8% patch (n = 282) or an optimised dose of oral pregabalin (n = 277), and assessed for a ≥30% mean decrease in Numeric Pain Rating Scale (NPRS) score from baseline to Week 8. Secondary endpoints included optimal therapeutic effect (OTE), time-to-onset of pain relief and treatment satisfaction. RESULTS: The capsaicin 8% patch was non-inferior to pregabalin in achievement of a ≥30% mean decrease in NPRS score from baseline to Week 8 (55.7% vs. 54.5%, respectively; Odds ratio: 1.03 [95% CI: 0.72, 1.50]). The proportion of patients achieving OTE at Week 8 was 52.1% for the capsaicin 8% patch versus 44.8% for pregabalin (difference: 7.3%; 95% CI: -0.9%, 15.6%). The median time-to-onset of pain relief was significantly shorter for capsaicin 8% patch versus pregabalin (7.5 vs. 36.0 days; Hazard ratio: 1.68 [95% CI: 1.35, 2.08]; p < 0.0001). Treatment satisfaction was also significantly greater with the capsaicin 8% patch versus pregabalin. TEAEs were mild-to-moderate in severity, and resulted in treatment discontinuation only with pregabalin (n = 24). Systemic adverse drug reactions ranged from 0 to 1.1% with capsaicin 8% patch and 2.5 to 18.4% with pregabalin. CONCLUSIONS: The capsaicin 8% patch provided non-inferior pain relief to an optimized dose of pregabalin in PNP, with a faster onset of action, fewer systemic side effects and greater treatment satisfaction.

EFNS guidelines on the pharmacological treatment of neuropathic pain: 2010 revision.

BACKGROUND AND OBJECTIVES: This second European Federation of Neurological Societies Task Force aimed at updating the existing evidence about the pharmacological treatment of neuropathic pain since 2005. METHODS: Studies were identified using the Cochrane Database and Medline. Trials were classified according to the aetiological condition. All class I and II randomized controlled trials (RCTs) were assessed; lower class studies were considered only in conditions that had no top-level studies. Treatments administered using repeated or single administrations were considered, provided they are feasible in an outpatient setting. RESULTS: Most large RCTs included patients with diabetic polyneuropathies and post-herpetic neuralgia, while an increasing number of smaller studies explored other conditions. Drugs generally have similar efficacy in various conditions, except in trigeminal neuralgia, chronic radiculopathy and HIV neuropathy, with level A evidence in support of tricyclic antidepressants (TCA), pregabalin, gabapentin, tramadol and opioids (in various conditions), duloxetine, venlafaxine, topical lidocaine and capsaicin patches (in restricted conditions). Combination therapy appears useful for TCA-gabapentin and gabapentin-opioids (level A). CONCLUSIONS: There are still too few large-scale comparative studies. For future trials, we recommend to assess comorbidities, quality of life, symptoms and signs with standardized tools and attempt to better define responder profiles to specific drug treatments.

Practice parameter: the diagnostic evaluation and treatment of trigeminal neuralgia (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology and the European Federation of Neurological Societies.

BACKGROUND: Trigeminal neuralgia (TN) is a common cause of facial pain. PURPOSE: To answer the following questions: 1) In patients with TN, how often does routine neuroimaging (CT, MRI) identify a cause? 2) Which features identify patients at increased risk for symptomatic TN (STN; i.e., a structural cause such as a tumor)? 3) Does high-resolution MRI accurately identify patients with neurovascular compression? 4) Which drugs effectively treat classic and symptomatic trigeminal neuralgia? 5) When should surgery be offered? 6) Which surgical technique gives the longest pain-free period with the fewest complications and good quality of life? METHODS: Systematic review of the literature by a panel of experts. CONCLUSIONS: In patients with trigeminal neuralgia (TN), routine head imaging identifies structural causes in up to 15% of patients and may be considered useful (Level C). Trigeminal sensory deficits, bilateral involvement of the trigeminal nerve, and abnormal trigeminal reflexes are associated with an increased risk of symptomatic TN (STN) and should be considered useful in distinguishing STN from classic trigeminal neuralgia (Level B). There is insufficient evidence to support or refute the usefulness of MRI to identify neurovascular compression of the trigeminal nerve (Level U). Carbamazepine (Level A) or oxcarbazepine (Level B) should be offered for pain control while baclofen and lamotrigine (Level C) may be considered useful. For patients with TN refractory to medical therapy, Gasserian ganglion percutaneous techniques, gamma knife, and microvascular decompression may be considered (Level C). The role of surgery vs pharmacotherapy in the management of TN in patients with MS remains uncertain.

AAN-EFNS guidelines on trigeminal neuralgia management.

Several issues regarding diagnosis, pharmacological treatment, and surgical treatment of trigeminal neuralgia (TN) are still unsettled. The American Academy of Neurology and the European Federation of Neurological Societies launched a joint Task Force to prepare general guidelines for the management of this condition. After systematic review of the literature the Task Force came to a series of evidence-based recommendations. In patients with TN MRI may be considered to identify patients with structural causes. The presence of trigeminal sensory deficits, bilateral involvement, and abnormal trigeminal reflexes should be considered useful to disclose symptomatic TN, whereas younger age of onset, involvement of the first division, unresponsiveness to treatment and abnormal trigeminal evoked potentials are not useful in distinguishing symptomatic from classic TN. Carbamazepine (stronger evidence) or oxcarbazepine (better tolerability) should be offered as first-line treatment for pain control. For patients with TN refractory to medical therapy early surgical therapy may be considered. Gasserian ganglion percutaneous techniques, gamma knife and microvascular decompression may be considered. Microvascular decompression may be considered over other surgical techniques to provide the longest duration of pain freedom. The role of surgery versus pharmacotherapy in the management of TN in patients with multiple sclerosis remains uncertain.

Volunteer studies in pain research--opportunities and challenges to replace animal experiments: the report and recommendations of a Focus on Alternatives workshop.

Despite considerable research, effective and safe treatments for human pain disorders remain elusive. Understanding the biology of different human pain conditions and researching effective treatments continue to be dominated by animal models, some of which are of limited value. British and European legislation demands that non-animal approaches should be considered before embarking on research using experimental animals. Recent scientific and technical developments, particularly in human neuroimaging, offer the potential to replace some animal procedures in the study of human pain. A group of pain research experts from academia and industry met with the aim of exploring creatively the tools, strategies and challenges of replacing some animal experiments in pain research with ethically conducted studies of human patients and healthy volunteers, in combination with in vitro methods. This report considers how a range of neuroimaging techniques including functional magnetic resonance imaging, magnetoencephalography and positron emission tomography, singly and combined, can address human pain conditions. In addition, microdialysis in human subjects; genome-wide association research, twin studies and other epidemiological approaches; and in vitro cell and tissue research, are examined for their replacement potential in combination with neuroimaging. Recommendations highlight further opportunities to advance the replacement of animal studies with robust methods of relevance to understanding and treating human pain.

Phantom limb pain, cortical reorganization and the therapeutic effect of mental imagery.

Using functional MRI (fMRI) we investigated 13 upper limb amputees with phantom limb pain (PLP) during hand and lip movement, before and after intensive 6-week training in mental imagery. Prior to training, activation elicited during lip purse showed evidence of cortical reorganization of motor (M1) and somatosensory (S1) cortices, expanding from lip area to hand area, which correlated with pain scores. In addition, during imagined movement of the phantom hand, and executed movement of the intact hand, group maps demonstrated activation not only in bilateral M1 and S1 hand area, but also lip area, showing a two-way process of reorganization. In healthy participants, activation during lip purse and imagined and executed movement of the non-dominant hand was confined to the respective cortical representation areas only. Following training, patients reported a significant reduction in intensity and unpleasantness of constant pain and exacerbations, with a corresponding elimination of cortical reorganization. Post hoc analyses showed that intensity of constant pain, but not exacerbations, correlated with reduction in cortical reorganization. The results of this study add to our current understanding of the pathophysiology of PLP, underlining the reversibility of neuroplastic changes in this patient population while offering a novel, simple method of pain relief.

Neuropathic pain: redefinition and a grading system for clinical and research purposes.

Pain usually results from activation of nociceptive afferents by actually or potentially tissue-damaging stimuli. Pain may also arise by activity generated within the nervous system without adequate stimulation of its peripheral sensory endings. For this type of pain, the International Association for the Study of Pain introduced the term neuropathic pain, defined as "pain initiated or caused by a primary lesion or dysfunction in the nervous system." While this definition has been useful in distinguishing some characteristics of neuropathic and nociceptive types of pain, it lacks defined boundaries. Since the sensitivity of the nociceptive system is modulated by its adequate activation (e.g., by central sensitization), it has been difficult to distinguish neuropathic dysfunction from physiologic neuroplasticity. We present a more precise definition developed by a group of experts from the neurologic and pain community: pain arising as a direct consequence of a lesion or disease affecting the somatosensory system. This revised definition fits into the nosology of neurologic disorders. The reference to the somatosensory system was derived from a wide range of neuropathic pain conditions ranging from painful neuropathy to central poststroke pain. Because of the lack of a specific diagnostic tool for neuropathic pain, a grading system of definite, probable, and possible neuropathic pain is proposed. The grade possible can only be regarded as a working hypothesis, which does not exclude but does not diagnose neuropathic pain. The grades probable and definite require confirmatory evidence from a neurologic examination. This grading system is proposed for clinical and research purposes.

EFNS guidelines on pharmacological treatment of neuropathic pain.

Neuropathic pain treatment remains unsatisfactory despite a substantial increase in the number of trials. This EFNS Task Force aimed at evaluating the existing evidence about the pharmacological treatment of neuropathic pain. Studies were identified using first the Cochrane Database then Medline. Trials were classified according to the aetiological condition. All class I and II controlled trials (according to EFNS classification of evidence) were assessed, but lower-class studies were considered in conditions that had no top level studies. Only treatments feasible in an outpatient setting were evaluated. Effects on pain symptoms/signs, quality of life and comorbidities were particularly searched for. Most of the randomized controlled trials included patients with postherpetic neuralgia (PHN) and painful polyneuropathies (PPN) mainly caused by diabetes. These trials provide level A evidence for the efficacy of tricyclic antidepressants, gabapentin, pregabalin and opioids, with a large number of class I trials, followed by topical lidocaine (in PHN) and the newer antidepressants venlafaxine and duloxetine (in PPN). A small number of controlled trials were performed in central pain, trigeminal neuralgia, other peripheral neuropathic pain states and multiple-aetiology neuropathic pains. The main peripheral pain conditions respond similarly well to tricyclic antidepressants, gabapentin, and pregabalin, but some conditions, such as HIV-associated polyneuropathy, are more refractory. There are too few studies on central pain, combination therapy, and head-to-head comparison. For future trials, we recommend to assess quality of life and pain symptoms or signs with standardized tools.

Treatment of postherpetic neuralgia.

Postherpetic neuralgia (PHN) remains one of the most troublesome common chronic neuropathic pain conditions. Many controlled trials have been published showing good efficacy and reasonable tolerability. These include gabapentinoids, opioids, tricyclic antidepressants, and topical lidocaine and capsaicin. Combination therapies are possible, but have not been proven, and long-term follow-up is limited. Only few case series exist for surgical and other invasive therapies and their role remains uncertain.

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.

IL-10 gene polymorphism and herpesvirus infections.

Genetics has an important role in resistance to various infections and it also may modify the clinical picture of an infectious disease. Here, we briefly review our recent data demonstrating that the polymorphism of the IL-10 gene is associated with resistance to some common herpesviruses and, additionally, that this same gene is involved in the regulation of the severity of the infection and in the reactivation process.