Triggering trigeminal neuralgia

Introduction: Although it is widely accepted that facial pain paroxysms triggered by innocuous stimuli constitute a hallmark sign of trigeminal neuralgia, very few studies to date have systematically investigated the role of the triggers involved. In the recently published diagnostic classification, triggered pain is an essential criterion for the diagnosis of trigeminal neuralgia but no study to date has been designed to address this issue directly. In this study, we set out to determine, in patients with trigeminal neuralgia, how frequently triggers are present, which manoeuvres activate them and where cutaneous and mucosal trigger zones are located. Methods: Clinical characteristics focusing on trigger factors were collected from 140 patients with trigeminal neuralgia, in a cross-sectional study design. Results: Provocation of paroxysmal pain by various trigger manoeuvres was reported by 136 of the 140 patients. The most frequent manoeuvres were gentle touching of the face (79%) and talking (54%). Trigger zones were predominantly reported in the perioral and nasal region. Conclusion: This study confirms that in trigeminal neuralgia, paroxysmal pain is associated with triggers in virtually all patients and supports the use of triggers as an essential diagnostic feature of trigeminal neuralgia

Combination of pharmacotherapy and lidocaine analgesic block of the peripheral trigeminal branches for trigeminal neuralgia: a pilot study

Classical trigeminal neuralgia (CTN) is treated predominantly by pharmacotherapy but side effects and unsuccessful occurs. The current study was carried out to evaluate the therapeutic effect of combination of pharmacotherapy and lidocaine block. Thirteen patients with CTN managed with pharmacotherapy were recruited and assigned either to no additional treatment (Group I) or to additional analgesic block (Group II). The primary endpoint was the reduction in the frequency of pain episodes in a month assessed at 30 and 90 days. Comparisons of measurements of pain, general health and depression scales were secondary endpoints. The results from the follow-up visits at 30 and 90 days showed the Group II to have larger reduction in the frequency of pain and exhibited a bigger improvement in the scores of the pain, general health and depression scales. The results from this preliminary study suggest a clinical benefit of the combination of pharmacotherapy and lidocaine block

Cranial neuralgias: from physiopathology to pharmacological treatment

Cranial neuralgias are paroxysmal painful disorders of the head characterised by some shared features such as unilaterality of symptoms, transience and recurrence of attacks, superficial and "shock-like" quality of pain and the presence of triggering factors. Although rare, these disorders must be promptly recognised as they harbour a relatively high risk for underlying compressive or inflammatory disease. Nevertheless, misdiagnosis is frequent. Trigeminal and glossopharyngeal neuralgias are sustained in most cases by a neurovascular conflict in the posterior fossa resulting in a hyperexcitability state of the trigeminal circuitry. If the aetiology of trigeminal neuralgia (TN) and other typical neuralgias must be brought back to the peripheral injury, their pathogenesis could involve central allodynic mechanisms, which, in patients with inter-critical pain, also engage the nociceptive neurons at the thalamic-cortical level. Currently available medical treatments for TN and other cranial neuralgias are reviewed

Varicella-Zoster viruses associated with post-herpetic neuralgia induce sodium current density increases in the ND7-23 Nav-1.8 neuroblastoma cell line

Post-herpetic neuralgia (PHN) is the most significant complication of herpes zoster caused by reactivation of latent Varicella-Zoster virus (VZV). We undertook a heterologous infection in vitro study to determine whether PHN-associated VZV isolates induce changes in sodium ion channel currents known to be associated with neuropathic pain. Twenty VZV isolates were studied blind from 11 PHN and 9 non-PHN subjects. Viruses were propagated in the MeWo cell line from which cell-free virus was harvested and applied to the ND7/23-Nav1.8 rat DRG x mouse neuroblastoma hybrid cell line which showed constitutive expression of the exogenous Nav 1.8, and endogenous expression of Nav 1.6 and Nav 1.7 genes all encoding sodium ion channels the dysregulation of which is associated with a range of neuropathic pain syndromes. After 72 hrs all three classes of VZV gene transcripts were detected in the absence of infectious virus. Single cell sodium ion channel recording was performed after 72 hr by voltage-clamping. PHN-associated VZV significantly increased sodium current amplitude in the cell line when compared with non-PHN VZV, wild-type (Dumas) or vaccine VZV strains ((POka, Merck and GSK). These sodium current increases were unaffected by acyclovir pre-treatment but were abolished by exposure to Tetrodotoxin (TTX) which blocks the TTX-sensitive fast Nav 1.6 and Nav 1.7 channels but not the TTX-resistant slow Nav 1.8 channel. PHN-associated VZV sodium current increases were therefore mediated in part by the Nav 1.6 and Nav 1.7 sodium ion channels. An additional observation was a modest increase in message levels of both Nav1.6 and Nav1.7 mRNA but not Nav 1.8 in PHN virally infected cells

Challenges recruiting to a proof-of-concept pharmaceutical trial for a rare disease: The trigeminal neuralgia experience

Background: This study aimed to describe recruitment challenges encountered during a phase IIa study of vixotrigine, a state and use-dependent Nav1.7 channel blocker, in individuals with trigeminal neuralgia. Methods: This was an international, multicenter, placebo-controlled, randomized withdrawal study that included a 7-day run-in period, a 21-day open-label phase, and a 28-day double-blind phase in which patients (planned n = 30) were randomized to vixotrigine or placebo. Before recruitment, all antiepileptic drugs had to be stopped, except for gabapentin or pregabalin. After the trial, patients returned to their original medications. Patient recruitment was expanded beyond the original five planned (core) centers in order to meet target enrollment (total recruiting sites N = 25). Core sites contributed data related to patient identification for study participation (prescreening data). Data related to screening failures and study withdrawal were also analyzed using descriptive statistics. Results: Approximately half (322/636; 50.6%) of the patients who were prescreened at core sites were considered eligible for the study and 56/322 (17.4%) were screened. Of those considered eligible, 26/322 (8.1%) enrolled in the study and 6/322 (1.9%) completed the study. In total, 125 patients were screened across all study sites and 67/125 (53.6%) were enrolled. At prescreening, reasons for noneligibility varied by site and were most commonly diagnosis change (78/314; 24.8%), age > 80 years (75/314; 23.9%), language/distance/mobility (61/314; 19.4%), and noncardiac medical problems (53/314; 16.9%). At screening, frequently cited reasons for noneligibility included failure based on electrocardiogram, insufficient pain, and diagnosis change. Conclusions: Factors contributing to recruitment challenges encountered in this study included diagnosis changes, anxiety over treatment changes, and issues relating to distance, language, and mobility. Wherever possible, future studies should be designed to address these challenges. Trial registration: ClinicalTrials.gov, NCT01540630. EudraCT, 2010-023963-16. 07 Aug 2015

Genitofemoral neuralgia : adding to the burden of chronic vulvar pain

The vulva is a particularly common locus of chronic pain with neuropathic characteristics that occurs in women of any age, though most women with neuropathic type chronic vulvar pain will remain undiagnosed even following multiple physician visits. Here, we report on an exemplary case of a middle-aged woman who was referred to the Vulvovaginal Disease Clinic with debilitating vulvar burning and itching over the right labium majus that had been persisting for 2 years and was considered intractable. Careful history taking and clinical examination, followed by electrophysiological assessment through somatosensory evoked potentials was consistent with genitofemoral neuralgia, for which no obvious cause could be identified. Adequate pain relief was obtained with a serotonin-noradrenaline reuptake inhibitor and topical gabapentin cream. We briefly discuss the epidemiology, diagnosis, and treatment of genitofemoral neuralgia and provide a series of clues to guide clinicians in obtaining a presumptive diagnosis of specific neuropathic pain syndromes that may underlie chronic vulvar pain. We further aim to draw attention to the tremendous burden of chronic, unrecognized vulvar pain

Trigeminal neuralgia - diagnosis and treatment

Introduction Trigeminal neuralgia (TN) is characterized by touch-evoked unilateral brief shock-like paroxysmal pain in one or more divisions of the trigeminal nerve. In addition to the paroxysmal pain, some patients also have continuous pain. TN is divided into classical TN (CTN) and secondary TN (STN). Etiology and pathophysiology Demyelination of primary sensory trigeminal afferents in the root entry zone is the predominant pathophysiological mechanism. Most likely, demyelination paves the way for generation of ectopic impulses and ephaptic crosstalk. In a significant proportion of the patients, the demyelination is caused by a neurovascular conflict with morphological changes such as compression of the trigeminal root. However, there are also other unknown etiological factors, as only half of the CTN patients have morphological changes. STN is caused by multiple sclerosis or a space-occupying lesion affecting the trigeminal nerve. Differential diagnosis and treatment Important differential diagnoses include trigeminal autonomic cephalalgias, posttraumatic or postherpetic pain and other facial pains. First line treatment is prophylactic medication with sodium channel blockers, and second line treatment is neurosurgical intervention. Future perspectives Future studies should focus on genetics, unexplored etiological factors, sensory function, the neurosurgical outcome and complications, combination and neuromodulation treatment as well as development of new drugs with better tolerability

A systematic review and meta-analysis of risk factors for postherpetic neuralgia.

Patients with herpes zoster can develop persistent pain after rash healing, a complication known as postherpetic neuralgia. By preventing zoster through vaccination, the risk of this common complication is reduced. We searched MEDLINE and Embase for studies assessing risk factors for postherpetic neuralgia, with a view to informing vaccination policy. Nineteen prospective studies were identified. Meta-analysis showed significant increases in the risk of postherpetic neuralgia with clinical features of acute zoster including prodromal pain (summary rate ratio 2.29, 95% confidence interval: 1.42-3.69), severe acute pain (2.23, 1.71-2.92), severe rash (2.63, 1.89-3.66), and ophthalmic involvement (2.51, 1.29-4.86). Older age was significantly associated with postherpetic neuralgia; for individual studies, relative risk estimates per 10-year increase ranged from 1.22 to 3.11. Evidence for differences by gender was conflicting, with considerable between-study heterogeneity. A proportion of studies reported an increased risk of postherpetic neuralgia with severe immunosuppression (studies, n = 3/5) and diabetes mellitus (n = 1/4). Systemic lupus erythematosus, recent trauma, and personality disorder symptoms were associated with postherpetic neuralgia in single studies. No evidence of higher postherpetic neuralgia risk was found with depression (n = 4) or cancer (n = 5). Our review confirms a number of clinical features of acute zoster are risk factors for postherpetic neuralgia. It has also identified a range of possible vaccine-targetable risk factors for postherpetic neuralgia; yet aside from age-associated risks, evidence regarding risk factors to inform zoster vaccination policy is currently limited

Clinical and psychosocial correlates of post-herpetic neuralgia

Post-herpetic neuralgia is the most challenging and debilitating complication of herpes zoster in the immunocompetent host. Because the effect of treatment is disappointing once the syndrome has developed, it is important to know which factors predict post-herpetic neuralgia occurrence to facilitate selection of herpes zoster patients with a higher risk of developing neuralgia and undertake preventative strategies. The present study aimed at identifying demographic, clinical and psychosocial correlates of post-herpetic neuralgia in a sample of 219 immunocompetent patients, who were examined by dermatologists in private practice in Italy and who completed a questionnaire designed to evaluate their clinical and psychosocial profile at the time of clinical diagnosis of herpes zoster and at a follow-up visit 6 months later. In a univariate analysis, post-herpetic neuralgia was associated significantly with older age, longer duration of prodromal pain, greater acute pain intensity, greater extent of rash, presence of abnormal sensations and use of systemic antiviral therapy. Compared to the values at herpes zoster onset, at the follow-up visit patients with post-herpetic neuralgia presented with similar high mean scores of pain intensity, anxiety and depression and greatly reduced quality of life, whereas patients without neuralgia presented with improved scores. In a multivariate model, older age, greater acute pain intensity, greater extent of rash and longer duration of prodromal pain were independently associated with post-herpetic neuralgia. The results of this study may help physicians to identify patients with a higher risk of developing post-herpetic neuralgia and undertaking preventative strategies