Idiopathic Orofacial Pain Research Articles

Small Fiber Neuropathy in Burning Mouth Syndrome: A Systematic Review

Burning mouth syndrome (BMS) is a chronic idiopathic orofacial pain disorder, characterized by persistent burning sensations and pain without clear pathological causes. Recent research suggests that small fiber neuropathy (SFN) may play a significant role in the neuropathic pain and sensory disturbances associated with BMS. Following PRISMA guidelines, this systematic review aims to evaluate and synthesize current evidence supporting SFN’s involvement in BMS. The protocol is registered in PROSPERO (CRD42024555839). The results show eight studies reported reductions in nerve fiber density in tongue biopsies (ranging from 30% to 60%), along with morphological changes indicative of small fiber damage. Additionally, an increase in TRPV1-positive, NGF-positive, and P2X3-positive fibers, overexpression of Nav1.7, and slight underexpression of Nav1.9 mRNA were observed in BMS patients. Quantitative Sensory Testing in seven studies revealed sensory abnormalities such as reduced cool detection and cold pain thresholds. Blink reflex and corneal confocal microscopy also indicated peripheral and central small fiber damage, along with increased artemin mRNA expression. The evidence strongly supports SFN as a key factor in the pathophysiology of BMS, particularly due to reductions in nerve fiber density and altered sensory thresholds. However, variability across studies highlights the need for larger, standardized research to establish causal relationships and guide therapeutic strategies.

Idiopathic orofacial and nociplastic pain in elderly patients: a narrative review

Idiopathic orofacial and nociplastic pain in elderly patients: a narrative review

Temporomandibular disorders, neuropathic and idiopathic orofacial pain, and headaches: a literature review

Temporomandibular disorders, neuropathic and idiopathic orofacial pain, and headaches: a literature review

Orofacial Migraine and Other Idiopathic Non-Dental Facial Pain Syndromes: A Clinical Survey of a Social Orofacial Patient Group.

Background: Orofacial pain syndromes (OFPs) are a heterogeneous group of syndromes mainly characterized by painful attacks localized in facial and oral structures. According to the International Classification of Orofacial Pain (ICOP), the last three groups (non-dental facial pain, NDFP) are cranial neuralgias, facial pain syndromes resembling primary headache syndromes, and idiopathic orofacial pain. These are often clinical challenges because the symptoms may be similar or common among different disorders. The diagnostic efforts often induce a complex diagnostic algorithm and lead to several imaging studies or specialized tests, which are not always necessary. The aim of this study was to describe the encountered difficulties by these patients during the diagnostic-therapeutic course. Methods: This study was based on the responses to a survey questionnaire, administered to an Italian Facebook Orofacial Patient Group, searching for pain characteristics and diagnostic-therapeutic care courses. The questionnaire was filled out by patients affected by orofacial pain, who were 18 years and older, using a free online tool available on tablets, smartphones, and computers. Results: The sample was composed of 320 subjects (244F/76M), subdivided by age range (18-35 ys: 17.2%; 36-55 ys: 55.0%; >55 ys 27.8%). Most of the patients were affected by OFP for more than 3 years The sample presented one OFP diagnosis in 60% of cases, more than one in 36.2% of cases, and 3.8% not classified. Trigeminal neuralgia is more represented, followed by cluster headaches and migraines. About 70% had no pain remission, showing persisting background pain (VAS median = 7); autonomic cranial signs during a pain attack ranged between 45 and 65%. About 70% of the subjects consulted at least two different specialists. Almost all received drug treatment, about 25% received four to nine drug treatments, 40% remained unsatisfied, and almost 50% received no pharmacological treatment, together with drug therapy. Conclusion: To the authors' knowledge, this is the first study on an OFP population not selected by a third-level specialized center. The authors believe this represents a realistic perspective of what orofacial pain subjects suffer during their diagnostic-therapeutic course and the medical approach often results in unsatisfactory outcomes.

Idiopathic Non-Dental Facial Pain Syndromes in Italian Children: A Clinical Case Series.

The orofacial pain syndromes (OFPs) are a heterogeneous group of syndromes characterized by painful attacks involving the orofacial structures. They may be summarily subdivided into two great categories: (1) orofacial pain mainly attributed to dental disorders such as dentoalveolar and myofascial orofacial pain or temporomandibular joint (TM) pain; (2) orofacial pain mainly attributed to non-dental pain as neuralgias, facial localization of primary headaches or idiopathic orofacial pain. The second group is uncommon, often described by single case reports, can often show overlapping symptoms with the first group, and represents a clinical challenge, carrying the risk of undervaluation and possibly invasive odontoiatric treatment. We aimed to describe a clinical pediatric series of non-dental orofacial pain and better to underline some topographic and clinical features associated with them. We retrospectively collected the data of children admitted to our headache centers (Bari, Palermo, Torino) from 2017 to 2021. Our inclusion criterion was the presence of non-dental orofacial pain following the topographic criteria of 3° International Classification of Headache Disorders (ICHD-3), and exclusion criteria included the pain syndromes attributed to the dental disorders and pain syndromes due to the secondary etiologies Results. Our sample comprised 43 subjects (23/20 M/F, in the range of ages 5-17). We classified them int: 23 primary headaches involving the facial territory during attacks, 2 facial trigeminal autonomic cephalalgias, 1 facial primary stabbing headache, 1 facial linear headache, 6 trochlear migraines, 1 orbital migraine 3 red ear syndrome and 6 atypical facial pain. All patients described debilitating pain for intensity (moderate/severe), 31 children had episodic attacks, and 12 had continuous pain. Almost all received drugs for acute treatment (less than 50% were satisfied), and some received non-pharmacological treatment associated with drug therapy Conclusion. Although rare OFP can occur in pediatric age, it can be debilitating if unrecognized and untreated, affecting the psychophysical well-being of young patients. We highlight the specific characteristics of the disorder for a more correct and earlier identification during the diagnostic process, already difficult in pediatric age, and to define the approach and possible treatment to prevent negative outcomes in adulthood.

Diagnosis and treatment of intractable idiopathic orofacial pain with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) has been reported to be associated with primary chronic pain syndromes, such as fibromyalgia, migraine, and chronic low back pain. Although idiopathic orofacial pain (IOP) is classified as burning mouth syndrome or persistent idiopathic facial or dentoalveolar pain and as a primary chronic pain, the association between IOP and ADHD has not been investigated. This retrospective cohort study investigated the severity of ADHD symptoms measured using the ADHD scale and the effects of treatment using ADHD drugs and the dopamine system stabilizer aripiprazole. The participants were 25 consecutive patients with refractory IOP referred to a psychiatrist and diagnosed with coexisting ADHD according to the Diagnostic and Statistical Manual of Mental Disorders-5. The ADHD scale scores were higher in patients with intractable IOP than those in the general population. Pharmacotherapy used in this study led to clinically significant improvements in pain, anxiety/depression, and pain catastrophizing. Intractable IOP and ADHD were shown to be associated. In the future, screening and pharmacotherapy for ADHD should be considered in the treatment of intractable IOP.

Place of placebo therapy in the treatment of burning mouth syndrome: A systematic review.

Burning mouth syndrome (BMS) is defined as an idiopathic orofacial pain with intraoral burning or dysesthesia. This systematic review aimed to analyze the scientific literature with regard to the effectiveness of placebo therapy in patients with BMS. A literature search was conducted through the PubMed-indexed journals within MEDLINE®, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), and Trip databases from their inception to May 31, 2022. The search terms were defined by combining (medical subject headings (MeSH) terms OR keywords) "burning mouth syndrome" AND (MeSH terms OR keywords) "placebo". Methodological quality assessments were performed utilizing the Joanna Briggs Institute (JBI) Critical Appraisal tool to attribute scores from 1 to 11 to the selected studies. The literature search, study selection and data extraction were carried out by 2 authors. Disagreements between the authors were resolved by the 3rd author, if necessary. A total of 44 articles met the inclusion criteria. After assessing full-text articles for eligibility, 20 articles were excluded. Consequently, 24 articles were retained. A total of 21 studies included in this systematic review had a low score of bias. In 13 studies, a positive response to placebo was noted. Among them, 7 showed a placebo response indistinguishable from active treatment. These changes were more pronounced in patients receiving placebo therapy compared to active treatment in 1 study. Placebo therapy may occasionally be beneficial and ethically acceptable for patients with BMS. To get stronger evidence for the use of a placebo, future studies with standardized methodology and outcomes are required.

Gesichtsschmerzerkrankungen mit Relevanz für die Mund‑, Kiefer- und Gesichtschirurgie

Orofacial pain plays a significant role in oral and maxillofacial surgery diagnostics. Patients suffering from orofacial pain present symptoms that are often initially difficult to classify because of the lack of a dental correlate as a physical focus. The International Classification of Orofacial Pain provides an overview of orofacial pain disorders. Relevant representatives include trigeminal neuralgia and orofacial pain resembling the presentation of primary headache disorders such as facial migraine. Furthermore, posttraumatic neuropathic trigeminal pain and idiopathic orofacial pain are described. For these disorders, a strictly conservative approach with involvement of neurologic outpatient clinics specializing in orofacial pain, early pain psychology referral, and attunement to a long treatment duration is recommended.

A Randomized Controlled Trial Evaluating the Levels of the Biomarkers hs-CRP, IL-6, and IL-8 in Patients with Temporomandibular Disorder Treated with LLLT, Traditional Conservative Treatment, and a Combination of Both.

Temporomandibular disorders (TMDs) are a type of idiopathic orofacial pain. Inflammation, particularly elevated circulating levels of high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), and interleukin-8 (IL-8), has been linked to pain symptoms. The purpose of this study was to compare hs-CRP, IL-6, and IL-8 biomarkers and pain intensity with different treatment strategies (LLLT, standard conservative treatment, and combination) for TMD patients. Methods: A total of 32 participants were randomly included in the study and divided into three groups (Group I, Group II, and Group III) referred from the Dental Clinic, School of Dental Science, HUSM. Patients received LLLT (Groups II and III) in five sessions for the duration of 10 days. Patients in Groups I and III received standard conservative TMD treatment (diet and stress counseling, jaw exercises, physical therapy, which was a hot towel application) by the principal investigator. All blood samples for biomarkers were performed before starting treatments and directly after finishing the treatment protocols, where all results were recorded. Results: The result showed a significant difference in the mean IL-8 (p = 0.001) between the three intervention groups (LLLT, standard treatment, and combined treatment). IL-6 showed an increase in the mean of IL-6 levels from baseline to post-treatment with a better mean in the LLLT treatment group without any significant differences. Additionally, there were no significant mean differences found between the groups and in the group for the hs-CRP biomarker. Conclusions: A statistically non-significant difference was found in hs-CRP and IL-6 before and after LLLT, conservative, and combined treatment strategies of TMD. A statistically significant difference was observed in the mean levels of IL-8 between the LLLT intervention group and the combined treatment group. Although there was no statistically significant correlation between pain intensity and biomarkers, a statistically significant difference was found in pain intensity before and after LLLT, conservative, and combined treatment strategies. TMJ degeneration could be exacerbated by elevated IL-8 levels. Thus, this can be an important biomarker to mark or identify the painful condition of TMJ.

Burning Mouth Syndrome Etiology: A Narrative Review.

Burning mouth syndrome (BMS) is defined as "idiopathic orofacial pain with intraoral burning or dysesthesia recurring daily for more than 2 hours per day and more than 3 months, without any identifiable causative lesions, with or without somatosensory changes" in International Classification of Orofacial Pain, 2020. Worldwide prevalence of BMS was estimated to be 1.73% in population-based studies, while female and elderly are at higher risk of BMS. The aim of this narrative review is to clarify the main etiopathogenetic factors of BMS investigated so far in the scientific literature. There is growing evidence of an important role of peripheral neuropathology in BMS, supported by immunohistochemical studies which have demonstrated a significant loss of epithelial and subepithelial nerve fibers. Other possible etiopathogenetic factors emerging from literature are laryngopharyngeal reflux and hormonal and salivary changes related to aging and menopause. Finally, the role of the oral microbiota in BMS has not yet been thoroughly investigated. Further studies are necessary to investigate the probably multifactorial etiopathogenesis of primary BMS, a pathology which has a serious impact on the quality of life of our patients, a disease we find ourselves treating without the adequate therapy and the necessary knowledge.

Sleep moderates the effect of positive affect on circulating interleukin-6 in patients with temporomandibular disorder

Temporomandibular disorders (TMD) are idiopathic orofacial pain conditions. Inflammation—particularly elevated circulating levels of interleukin-6 (IL-6)—is associated with pain symptoms. Prior work in healthy samples has shown that trait positive affect (PA) is associated with lower IL-6, but that poor sleep attenuates PA and elevates IL-6. Although poor sleep has been associated with increased IL-6 in chronic pain, the effects of trait PA on IL-6 and potential moderation by sleep are not known. We thus investigated the effect of PA on circulating IL-6 and moderation of that effect by sleep, in 118 women with TMD and at least subclinical insomnia. Participants completed the insomnia severity index at baseline and subsequently completed a 14-day daily diary assessing sleep continuity, PA and negative affect. Sleep continuity was objectively assessed with wrist actigraphy over the same period. Both diary and actigraphy data were aggregated by computing person means. IL-6 was measured via blood samples obtained at 5 intervals prior to (i.e., resting), during and following an evoked pain testing session involving painful mechanical, heat and cold stimuli. PA did not predict resting or pain-evoked IL-6. However, multiple measures of sleep interacted with PA in the prediction of resting IL-6. Specifically, diary total sleep time (TST; b = -0.002, p = .003) and insomnia severity (b = .02, p = .03) moderated the effect of PA on resting IL-6, such that higher PA predicted lower resting IL-6 only when insomnia severity was lower or TST was higher. Remaining measures of sleep continuity were not significant moderators. Lower self-reported TST and higher insomnia severity eroded the salutary effects of PA on resting IL-6, underscoring sleep as a key intervention target in TMD. Modulation of positive affect's effect on IL-6 could be a pathway through which poor sleep impacts TMD-related outcomes. 3R01DE019731-05S1.

Burning mouth syndrome: An update

Background: Burning mouth syndrome (BMS) is a chronic and debilitating oral pain of the normal oral mucosa. It mainly affects women in their fifth to seventh decade. Its aetiopathogenesis remains unclear and is probably of multifactorial origin, with increasing evidence that BMS may be a neuropathic disorder. BMS is classified as an idiopathic (nociplastic) orofacial pain with or without somatosensory changes by International Classification of Orofacial Pain (ICOP 2020). The diagnosis of BMS, having excluded ‘oral burning mouth symptoms’, has evolved from basic intraoral exclusion screening to extensive clinical and laboratory investigations, which include the screening of comorbidities and other chronic pains and somatosensory testing. There is no standardised treatment in managing BMS, but a proposed combination of supportive and pharmacological treatment has been recommended. Aim: To review the current concepts of BMS definitions, classifications, aetiopathogenesis, diagnosis techniques, and evidence-based treatments in managing BMS patients. Conclusion: As BMS is a diagnosis by exclusion, thus a stratified approach is required for assessment of patients presenting BMS. A BMS diagnosis protocol is desired using a standardised screening to distinguish BMS from patient’s presenting with ‘oral burning symptoms’, and evaluation of comorbid chronic pain disorders or other medical comorbidities, which will include haematological, fungal, salivary flow, and qualitative sensory testing. Axis II and other additional quantitative sensory testing may further elucidate the causes of this condition. For future BMS prediction and prevention, will be based upon research on the relationship between other chronic pain disorders and familial history, environmental and genetic information.

Time-dependent responses in brain activity to ongoing hot stimulation in burning mouth syndrome.

Burning mouth syndrome (BMS) is classified into idiopathic orofacial pain conditions. Although central and peripheral neuropathic mechanisms are believed to be involved, the etiology remains to be fully elucidated. The present study examined temporal brain responses to an ongoing hot stimulus to investigate the pain modulating system in patients with BMS. The thermal stimulation sequence comprised baseline (32°C, 40 s) to warm (40°C, 32 s) to baseline (32°C, 40 s) to hot (49°C, 32 s), which was repeated four times using a Peltier thermode. These warm and hot stimuli were applied on the right palm and right lower lip in two separate sessions. Functional magnetic resonance imaging data were acquired by recording echo-planar images with a block design. Brain activity induced by purely hot stimulation (49°C vs. 40°C) applied to the palm was more pronounced than that induced by lip stimulation and in patients with BMS compared with controls. Comparison of brain activity between the first 16 s and second 16 s of the stimulus revealed pronounced time-dependent facilitation in patients with BMS during lip stimulation. These findings indicate that the pain modulating system in patients with BMS is dysregulated and that the brain in BMS is highly sensitized to pain information originating from the trigeminal system.

A Study on the Assessment of Haller Cells in Panoramic Radiograph.

Context:Haller cells are extensions of ethmoid cells which can be seen in several imaging modalities. Literature search has shown that idiopathic orofacial pain is associated with the presence of Haller cells. Hence, a simple cost-effective imaging modality for displaying the presence of Haller cells is desirable.Aims:This study aims to determine the prevalence of Haller cells in panoramic radiography.Subjects and Methods:The retrospective study comprised of 403 individuals of both genders. Panoramic radiograph was taken for every individual and interpreted for the presence of Haller cells. Factors incorporated in the interpretation were prevalence of Haller cells, distribution of Haller cells among genders, site predilection, unilocular or multilocular variant, and most common shape prevalent among the individuals.Statistical Analysis Used:Chi-square test with SPSS software.Results:Among 403 individuals, the Haller cells were present in 92 (22.8%) individuals. Of 92 (22.8%) individuals with Haller cells, 40 (18.5%) were males and 52 (27.8%) were females. Seventy-four individuals (80.4%) were unilocular and 18 (19.6%) were multilocular. Forty-five individuals had (48.9%) tear-shaped Haller cells, 27 (29.3%) had round-shaped Haller cells, and 20 (21.8%) had oval-shaped Haller cells. Forty (43.5%) were on the right side, 29 (31.5%) were on the left side, and 23 (25%) were on both sides.Conclusions:The present study assessed the prevalence of Haller cells as 22.8%, and this was done in a cost-effective way using panoramic radiographs.

He effects of low level laser therapy on the management of chronic idiopathic orofacial pain: trigeminal neuralgia, temporomandibular disorders and burning mouth syndrome

Aim: To investigate the efficacy of different wavelengths of low level laser therapy (LLLT) in the management of orofacial pain by measuring the pain reduction using visual analogue scale (VAS). Materials and methods: Study involved 20 patients with trigeminal neuralgia (TN), 20 with temporomandibular disorders (TMD) and 40 with burning mouth syndrome (BMS). 50 % of the patients in each syndrome group were treated with 660 nm laser, and other 50 % with 810 nm laser. Orofacial pain was quantified by the VAS. Results: VAS was significantly lower after the application of LLLT, in all subjects and for both applied wavelengths (P < 0.05). Efficacy of 810 nm laser compared to 660 nm laser was significantly higher for all patients and in both the TN and TMD groups (P < 0.001; P = 0.005; P = 0.024). Conclusions: LLLT has proven to be an effective intervention in reducing pain in TN, TMD and BMS patients. Better results can be achieved with higher wavelengths.

Co-occurrence of Pain Symptoms and Somatosensory Sensitivity in Burning Mouth Syndrome: A Systematic Review.

BackgroundBurning mouth syndrome (BMS) is a chronic and spontaneous oral pain with burning quality in the tongue or other oral mucosa without any identifiable oral lesion or laboratory finding. Pathogenesis and etiology of BMS are still unknown. However, BMS has been associated with other chronic pain syndromes including other idiopathic orofacial pain, the dynias group and the family of central sensitivity syndromes. This would imply that BMS shares common mechanisms with other cephalic and/or extracephalic chronic pains. The primary aim of this systematic review was to determine whether BMS is actually associated with other pain syndromes, and to analyze cephalic and extracephalic somatosensory sensitivity in these patients.MethodsThis report followed the PRISMA Statement. An electronic search was performed until January 2015 in PubMed, Cochrane library, Wiley and ScienceDirect. Searched terms included “burning mouth syndrome OR stomatodynia OR glossodynia OR burning tongue OR oral burning”. Studies were selected according to predefined inclusion criteria (report of an association between BMS and other pain(s) symptoms or of cutaneous cephalic and/or extracephalic quantitative sensory testing in BMS patients), and a descriptive analysis conducted.ResultsThe search retrieved 1512 reports. Out of these, twelve articles met criteria for co-occurring pain symptoms and nine studies for quantitative sensory testing (QST) in BMS patients. The analysis reveals that in BMS patients co-occurring pain symptoms are rare, assessed by only 0.8% (12 of 1512) of the retrieved studies. BMS was associated with headaches, TMD, atypical facial pain, trigeminal neuralgia, post-herpetic facial pain, back pain, fibromyalgia, joint pain, abdominal pain, rectal pain or vulvodynia. However, the prevalence of pain symptoms in BMS patients is not different from that in the age-matched general population. QST studies reveal no or inconsistent evidence of abnormal cutaneous cephalic and extracephalic somatosensory sensitivity.ConclusionsThere is no evidence for a high rate of other pain symptoms or somatosensory impairments co-occurring with BMS. These results thus suggest that BMS rather depends on specific mechanisms, likely at the trigeminal level. Nevertheless, more thoroughly conducted research is required to draw definitive conclusion.

Spatial and Temporal Brain Responses to Noxious Heat Thermal Stimuli in Burning Mouth Syndrome

Burning mouth syndrome (BMS) is an idiopathic orofacial pain condition. Although the pathophysiology of BMS is not clearly understood, central and peripheral neuropathic mechanisms are thought to be involved. The authors compared brain response to noxious heat stimuli in 16 right-handed women with primary BMS and 15 sex- and age-matched right-handed healthy female controls. A thermal stimulus sequence of 32 °C to 40 °C to 32 °C to 49 °C was repeated 4 times in a cycle. Warm and noxious heat stimuli were delivered with a Peltier thermode placed on the right palm or right lower lip for 32 s each in a session. Functional magnetic resonance imaging data were obtained by recording echoplanar images with a block design. Statistical Parametric Mapping 8 software was used to analyze the data. Patients and controls both reported feeling more pain during palm stimulation than during lip stimulation. Repetition of noxious heat stimulus on the lower lip but not on the palm induced habituation in brain activity in the cingulate cortex without reduction in pain perception. Multiple regression analysis revealed a correlation between perceived pain intensity and suppression of brain activity in the anterior cingulate cortex when the repeated thermal sequence was applied at the lower lip. Furthermore, the response of the parahippocampal area differed in BMS patients and controls when the same repeated thermal sequence was applied at the palm. The authors’ findings indicate that BMS patients show specific brain responses due to impaired function of the central and peripheral nervous systems (clinical trial registration: UMIN000015002).

Neurophysiological tests for facial-trigeminal pain

Comprehensive neurophysiological and psychophysical examination provides unique, sensitive and specific information about possible underlying neuropathy in patients with orofacial pain. Special ENMG techniques, brainstem reflex examinations, sensory and motor evoked potential recordings as well as quantitative sensory tests provide diagnostic biomarkers for large and small nerve fiber systems, and confirm definite diagnosis of neuropathic pain within the trigeminal distribution with up to 95–100% accuracy. They enable precise differential diagnosis between neuropathic and musculoskeletal pain within the orofacial area. Neurophysiological tests also allow accurate topographic level diagnosis from peripheral nerves to the cortex, helping to guide further imaging studies to the most likely region of underlying neuropathology, significantly increasing the overall diagnostic yield. Systematic application of neurophysiological testing has elucidated neural mechanisms of various orofacial pain conditions including trigeminal neuropathic pain, trigeminal neuralgia, persistent idiopathic orofacial pain, and burning mouth syndrome. Neurophysiological and psychophysical testing can also provide invaluable prognostic information regarding risk of persistent pain and recovery after nerve injury. Furthermore, clinical neurophysiology can measure and confirm phenomena associated with neuropathic pain, caused by deficient endogenous inhibitory systems or neuroplastic alterations. Neurophysiological tools enable more efficient treatment based on accurate diagnosis and individual profiling of the underlying pathophysiology.

An update on pathophysiological mechanisms related to idiopathic oro-facial pain conditions with implications for management.

Chronic oro-facial pain conditions such as persistent idiopathic facial pain (PIFP), atypical odontalgia (AO) and burning mouth syndrome (BMS), usually grouped together under the concept of idiopathic oro-facial pain, remain a diagnostic and therapeutic challenge. Lack of understanding of the underlying pathophysiological mechanisms of these pain conditions is one of the important reasons behind the problems in diagnostic and management. During the last two decades, neurophysiological, psychophysical, brain imaging and neuropathological methods have been systematically applied to study the trigeminal system in idiopathic oro-facial pain. The findings in these studies have provided evidence for neuropathic involvement in the pathophysiology of PIFP, AO and BMS. The present qualitative review is a joint effort of a group of oro-facial pain specialists and researchers to appraise the literature on idiopathic oro-facial pain with special focus on the currently available studies on their pathophysiological mechanisms. The implications of the findings of these studies for the clinical diagnosis and treatment of idiopathic oro-facial pain conditions are discussed.

Somatosensory Sensitivity in Patients With Persistent Idiopathic Orofacial Pain Is Associated With Pain Relief From Hypnosis and Relaxation

In a recent study hypnosis has been found to relieve persistent idiopathic orofacial pain. Quantitative sensory testing (QST) is widely used to evaluate somatosensory sensitivity, which has been suggested as a possible predictor of management outcome. The objectives of this study were to examine: (1) possible associations between clinical pain relief and baseline somatosensory sensitivity and (2) the effect of hypnosis management on QST parameters. Forty-one patients with persistent idiopathic orofacial pain completed this randomized controlled study in 1 of 2 groups: hypnosis (hypnotic analgesia suggestions) or control (relaxation). QST at 2 intraoral (pain region and contralateral mirror image region) and 3 extraoral (hand and both cheeks) sites was performed at baseline and after the hypnosis/control management, together with pressure pain thresholds and pressure pain tolerance thresholds determined bilaterally at the masseter and temporalis muscles, the temporomandibular joints, and the third finger. Degree of pain relief was negatively correlated with a summary statistic of baseline somatosensory sensitivity (summed z-score), that is, high baseline somatosensory sensitivity was associated with low pain relief (r=-0.372, P=0.020). Hypnosis had no major effect on any QST measure compared with relaxation (P>0.063). High pain sensitivity at baseline may predict poor pain management outcome. In addition, despite clear clinical pain relief, hypnosis did not significantly or specifically influence somatosensory sensitivity. Future studies should further explore QST measures as possible predictors of different management response in orofacial pain conditions.