A set of related medical disorders that lack a proper classification system and diagnostic criteria is like a society without laws. The result is incoherence at best, chaos at worst. For this reason, the International Classification of Headache Disorders (ICHD) is arguably the single most important breakthrough in headache medicine over the last 50 years. The ICHD identifies and categorizes more than a hundred different kinds of headache in a logical, hierarchal system. Even more important, it has provided explicit diagnostic criteria for all of the headache disorders listed. The ICHD quickly became universally accepted, and criticism of the classification has been minor relative to that directed at other disease classification systems. Over the 20 years following publication of the first edition of the ICHD, headache research has rapidly accelerated despite sparse allocation of resources to that effort. In summary, the ICHD has attained widespread acceptance at the international level and has substantially facilitated both clinical research and clinical care in the field of headache medicine.

International Classification of Headache Disorders

Topical capsaicin formulations are used for pain management. Safety and modest efficacy of low-concentration capsaicin formulations, which require repeated daily self-administration, are supported by meta-analyses of numerous studies. A high-concentration capsaicin 8% patch (Qutenza™) was recently approved in the EU and USA. A single 60-min application in patients with neuropathic pain produced effective pain relief for up to 12 weeks. Advantages of the high-concentration capsaicin patch include longer duration of effect, patient compliance, and low risk for systemic effects or drug–drug interactions. The mechanism of action of topical capsaicin has been ascribed to depletion of substance P. However, experimental and clinical studies show that depletion of substance P from nociceptors is only a correlate of capsaicin treatment and has little, if any, causative role in pain relief. Rather, topical capsaicin acts in the skin to attenuate cutaneous hypersensitivity and reduce pain by a process best described as ‘defunctionalization’ of nociceptor fibres. Defunctionalization is due to a number of effects that include temporary loss of membrane potential, inability to transport neurotrophic factors leading to altered phenotype, and reversible retraction of epidermal and dermal nerve fibre terminals. Peripheral neuropathic hypersensitivity is mediated by diverse mechanisms, including altered expression of the capsaicin receptor TRPV1 or other key ion channels in affected or intact adjacent peripheral nociceptive nerve fibres, aberrant re-innervation, and collateral sprouting, all of which are defunctionalized by topical capsaicin. Evidence suggests that the utility of topical capsaicin may extend beyond painful peripheral neuropathies.

Topical capsaicin for pain management: therapeutic potential and mechanisms of action of the new high-concentration capsaicin 8% patch

Trigeminal neuralgia (TN) is an exemplary condition of neuropathic facial pain. However, formally classifying TN as neuropathic pain based on the grading system of the International Association for the Study of Pain is complicated by the requirement of objective signs confirming an underlying lesion or disease of the somatosensory system. The latest version of the International Classification of Headache Disorders created similar difficulties by abandoning the term symptomatic TN for manifestations caused by major neurologic disease, such as tumors or multiple sclerosis. These diagnostic challenges hinder the triage of TN patients for therapy and clinical trials, and hamper the design of treatment guidelines. In response to these shortcomings, we have developed a classification of TN that aligns with the nosology of other neurologic disorders and neuropathic pain. We propose 3 diagnostic categories. Classical TN requires demonstration of morphologic changes in the trigeminal nerve root from vascular compression. Secondary TN is due to an identifiable underlying neurologic disease. TN of unknown etiology is labeled idiopathic. Diagnostic certainty is graded possible when pain paroxysms occur in the distribution of the trigeminal nerve branches. Triggered paroxysms permit the designation of clinically established TN and probable neuropathic pain. Imaging and neurophysiologic tests that establish the etiology of classical or secondary TN determine definite neuropathic pain.

https://n.neurology.org/content/neurology/87/2/220.full.pdf

Trigeminal neuralgia New classification and diagnostic grading for practice and research

PURPOSE

The aim of the paper is to identify, review, analyze, and summarize available evidence in three areas on the use of cross-sectional imaging, specifically maxillofacial cone beam computed tomography (CBCT) in pre- and postoperative dental implant therapy: (1) Available clinical use guidelines, (2) indications and contraindications for use, and (3) assessment of associated radiation dose risk.

MATERIALS AND METHODS

Three focused questions were developed to address the aims. A systematic literature review was performed using a PICO-based search strategy based on MeSH key words specific to each focused question of English-language publications indexed in the MEDLINE database retrospectively from October 31, 2012. These results were supplemented by a hand search and gray literature search.

RESULTS

Twelve publications were identified providing guidelines for the use of cross-sectional radiography, particularly CBCT imaging, for the pre- and/or postoperative assessment of potential dental implant sites. The publications discovered by the PICO strategy (43 articles), hand (12), and gray literature searches (1) for the second focus question regarding indications and contraindications for CBCT use in implant dentistry were either cohort or case-controlled studies. For the third question on the assessment of associated radiation dose risk, a total of 22 articles were included. Publication characteristics and themes were summarized in tabular format.

CONCLUSIONS

The reported indications for CBCT use in implant dentistry vary from preoperative analysis regarding specific anatomic considerations, site development using grafts, and computer-assisted treatment planning to postoperative evaluation focusing on complications due to damage of neurovascular structures. Effective doses for different CBCT devices exhibit a wide range with the lowest dose being almost 100 times less than the highest dose. Significant dose reduction can be achieved by adjusting operating parameters, including exposure factors and reducing the field of view (FOV) to the actual region of interest.

Cone beam computed tomography in implant dentistry: a systematic review focusing on guidelines, indications, and radiation dose risks.

Pathophysiology of primary burning mouth syndrome

Burning mouth syndrome as a trigeminal small fibre neuropathy: Increased heat and capsaicin receptor TRPV1 in nerve fibres correlates with pain score

Burning mouth syndrome as a trigeminal small fibre neuropathy: Increased heat and capsaicin receptor TRPV1 in spared nerve fibres correlates with pain score

Aims: To describe the cause, clinical signs, and symptoms of patients presenting to a tertiary care center with iatrogenic lesions to the mandibular branches of the trigeminal nerve. Methods: Pain history, pain scores using the visual analog scale, and mechanosensory testing results were recorded from 93 patients with iatrogenic lingual nerve injuries (LNI) and 90 patients with iatrogenic inferior alveolar nerve injuries (IANI). Results were analyzed using the SPSS statistical software. Chi-square tests were applied for nonparametric testing of frequencies, where P ≤ .05 indicated statistical significance. Appropriate correlations were also carried out between certain data sets. Results: Significantly more females were referred than males (P < .05). Overall, third molar surgery (TMS) caused 73% of LNI, followed by local anesthesia (LA) (17%). More diverse procedures caused IANI, including TMS (60%), LA (19%), implants (18%), and endodontics (8%). Approximately 70% of patients presented with neuropathic pain coincident with anesthesia and/or paresthesia. Neuropathy was demonstrable in all patients with varying degrees of loss of mechanosensory function, paresthesia, dysesthesia, allodynia, and hyperalgesia. Functionally, IANI and LNI patients mostly had problems with speech and eating, where speech was affected amongst significantly more patients with LNI (P < .001). Sleep, brushing teeth, and drinking were significantly more problematic for IANI patients (P < .05, P < .001, and P < .0001, respectively). Conclusion: Neuropathic pain, as well as anesthesia, frequently occurs following iatrogenic trigeminal nerve injury similar to other posttraumatic sensory nerve injuries. This must be acknowledged by clinicians as a relatively common problem and informed consent appropriately formulated for patients at risk of trigeminal nerve injuries in relation to dentistry requires revision. J Or O fac Pain 2011;25:333–344

/pdf/profiling-of-patients-presenting-with-posttraumatic-2bwue4shrw.pdf

Profiling of patients presenting with posttraumatic neuropathy of the trigeminal nerve

http://trigeminalnerve.org.uk/userfiles/Management%20of%20trigeminal%20nerve%20injureis_final%20online%20paper(1).pdf

Managing iatrogenic trigeminal nerve injury: a case series and review of the literature

Aims: To explore the impact of trigeminal nerve injuries on quality of life, including the effect of pain on psychological and affective function. Methods: An observational, cross-sectional survey design was employed. Fifty-six patients with inferior alveolar nerve injury (IANI) and 33 patients with lingual nerve injury (LNI) completed standardized self-report measures of pain intensity, pain catastrophizing, self-efficacy to cope with pain, and mood, in addition to generic and oral health-related quality of life (HRQoL) indicators. The impact of pain severity on these aspects of psychosocial function was examined. Summary statistics were calculated for all measures and compared with norms or values of other relevant studies, when available, using t tests. The impact of pain severity on these aspects of psychosocial function was examined using analysis of variance and hierarchical multivariate regression models. Results: The majority of patients reported pain associated with their nerve injury (86%). Nerve injury had a significant impact on all investigated domains, and this was closely linked with reported pain levels. Patients with severe pain showed particularly elevated levels of depression and pain catastrophizing, as well as substantially reduced HRQoL and coping efficacy levels. Pain intensity level was a significant predictor in all models except anxiety, uniquely contributing between 17% and 26% of variance to the prediction of pain catastrophizing, depression, coping efficacy, and generic and oral HRQoL. Conclusion: Traumatic injury to the trigeminal nerve is associated with a substantial patient burden, particularly in patients who experience severe neuropathic pain as part of their condition. These findings highlight the need to identify, develop, and evaluate more effective treatments for neuropathic pain in trigeminal nerve injury that will not only provide clinically meaningful reductions in pain but also improve patients’ quality of life. J Orofac Pain 2013;27:293–303. doi: 10.11607/jop.1056

http://trigeminalnerve.org.uk/userfiles/Smith%20et%20al_2013.pdf

Zehra Yilmaz

Papers

Burning mouth syndrome as a trigeminal small fibre neuropathy: Increased heat and capsaicin receptor TRPV1 in nerve fibres correlates with pain score

Burning mouth syndrome as a trigeminal small fibre neuropathy: Increased heat and capsaicin receptor TRPV1 in spared nerve fibres correlates with pain score

Profiling of patients presenting with posttraumatic neuropathy of the trigeminal nerve

Managing iatrogenic trigeminal nerve injury: a case series and review of the literature

The psychosocial and affective burden of posttraumatic neuropathy following injuries to the trigeminal nerve.