Persistent idiopathic facial pain exists independent of somatosensory input from the painful region: findings from quantitative sensory functions and somatotopy of the primary somatosensory cortex

Other Secondary Headaches: Odontogenic Pain and Other Painful Orofacial Conditions

This article discusses extremely common odontogenic pain conditions, which may occasionally present to the neurology clinic mimicking headache, and other uncommon orofacial pain conditions, which may do the same. Typical presentations, investigative strategies, and management are discussed, as well as highlighting key diagnostic criteria and the importance of involving oral or dental specialists where diagnostic uncertainty exists.

Persistent facial pain in post-stroke patients, a hospital-based cohort study; experience from North India

Background

Post-stroke pain is common after a stroke and might be underreported. We describe Persistent Facial Pain (PFP) developed in post-stroke patients.

Method

ology: This was a prospective hospital-based cohort study of stroke patients, and patients were followed up. Out of 415 stroke patients, 26 developed PFP.

Result

Out of all PFP patients, six patients had an ischemic stroke, and 20 had a hemorrhagic stroke. 57.7% of patients had hypertension, while 34.6 patients had diabetes. The stroke location was left-sided in 12 patients and right-sided in 14 patients. 46.15% of patients responded to venlafaxine, 30.77% responded to amitriptyline, and 23.08% responded to pregabalin.

Conclusion

Persistent facial pain is a pain syndrome that might be missed in patients post-stroke. It might be more common in hemorrhagic stroke patients than in ischemic stroke patients. It responds adequately to antidepressants. A high index of suspicion is required to diagnose and appropriately manage these patients.

The blink reflex and its modulation - Part 2: Pathophysiology and clinical utility

The blink reflex (BR) is integrated at the brainstem; however, it is modulated by inputs from various structures such as the striatum, globus pallidus, substantia nigra, and nucleus raphe magnus but also from afferent input from the peripheral nervous system. Therefore, it provides information about the pathophysiology of numerous peripheral and central nervous system disorders. The BR is a valuable tool for studying the integrity of the trigemino-facial system, the relevant brainstem nuclei, and circuits. At the same time, some neurophysiological techniques applying the BR may indicate abnormalities involving structures rostral to the brainstem that modulate or control the BR circuits. This is a state-of-the-art review of the clinical application of BR modulation; physiology is reviewed in part 1. In this review, we aim to present the role of the BR and techniques related to its modulation in understanding pathophysiological mechanisms of motor control and pain disorders, in which these techniques are diagnostically helpful. Furthermore, some BR techniques may have a predictive value or serve as a basis for follow-up evaluation. BR testing may benefit in the diagnosis of hemifacial spasm, dystonia, functional movement disorders, migraine, orofacial pain, and psychiatric disorders. Although the abnormalities in the integrity of the BR pathway itself may provide information about trigeminal or facial nerve disorders, alterations in BR excitability are found in several disease conditions. BR excitability studies are suitable for understanding the common pathophysiological mechanisms behind various clinical entities, elucidating alterations in top-down inhibitory systems, and allowing for follow-up and quantitation of many neurological syndromes.

Craniofacial disorders and headaches. A narrative review

OBJECTIVES

Craniofacial- and headache disorders are common co-morbid disorders. The aim of this review is to provide an overview of the research discussing craniofacial pain, especially temporomandibular disorders, and its relationship and impact on headaches, as well as suggestions for diagnostic assessment tools and physical therapeutic management strategies.

METHOD

A narrative structured review was performed. A search was conducted in MEDLINE using terms related to craniofacial pain and headaches. Additionally, papers regarding this topic were also extracted from the authors' personal libraries. Any study design (i.e., RCT, observational studies, systematic review, narrative review) that reported the concepts of interest was included, using Covidence. Results were narratively synthesized and described.

RESULTS

From an epidemiological perspective, craniofacial pain and headaches are strongly related and often co-existing. This may be due to the neuroanatomical connection with the trigeminal cervical complex, or due to shared predisposing factors such as age, gender, and psychosocial factors. Pain drawings, questionnaires, and physical tests can be used to determine the cause of pain, as well as other perpetuating factors in patients with headaches and craniofacial pain. The evidence supports different forms of exercise and a combination of hands-on and hands-off strategies aimed at both the craniofacial pain as well as the headache.

CONCLUSION

Headaches may be caused or aggravated by different disorders in the craniofacial region. Proper use of terminology and classification may help in understanding these complaints. Future research should look into the specific craniofacial areas and how headaches may arise from problems from those regions. (249 words).

Multimodal pain therapy for persistent idiopathic facial pain - a pilot study

OBJECTIVE

Persistent Idiopathic Facial Pain (PIFP) is a pain syndrome with missing evidence-based therapy recommendations. According to the biopsychosocial pain model, multidisciplinary pain treatment (MPT) offers a promising therapeutic option for chronic pain syndromes. MPT is an interprofessional treatment procedure, consisting of medical, physiotherapeutic and psychotherapeutic treatment units, which has not yet been studied in PIFP.

METHODS

This retrospective study included 25 patients with PIFP, who had been treated with MPT. Pain intensity on the numerical rating scale (NRS), perceived disability, habitual well-being, as well as anxiety/depression and stress scales were recorded. Moreover, the patients evaluated the efficacy of each type of the single therapeutic interventions.

RESULTS

There was a highly significant decrease in the characteristic pain intensity. Also habitual well-being improved significantly, as did anxiety and depression. The perceived disability and stress also improved, but without statistical significance. Physiotherapy was rated as the most effective therapeutic unit. Among the medical measures, consultations took first place (40% of the participants). Nearly three-fourths of the patients (72%) would recommend MPT.

CONCLUSION

The present study shows beneficial outcomes in patients with PIFP following MPT. Patients evaluate physiotherapeutic treatment as particularly efficacious. Therefore, MPT can be considered as a therapeutic option in patients with PIFP.

Effect of neuropathic pain on sphenopalatine ganglion block responses in persistent idiopathic facial pain

OBJECTIVES

Management of persistent idiopathic facial pain (PIFP) can be challenging. Sphenopalatine ganglion (SPG) has been the target for the interventional treatment of many facial pain syndromes. However, possible factors that may affect SPG block success are unknown. It was aimed to investigate the effect of neuropathic pain on SPG block outcomes in PIFP, which includes a heterogeneous patient group.

METHODS

All of the patients underwent fluoroscopy-guided SPG block with an injection of 40 mg of 2% lidocaine and 8 mg of dexamethasone. The patients were assigned to 2 groups according to existence of neuropathic pain determined with the DN4 questionnaire score: 19 patients with neuropathic pain (Group 1) and 15 patients without neuropathic pain (Group 2). Preprocedural and postprocedural Visual Analog Scale (VAS) scores were compared between the 2 groups.

RESULTS

The mean age of the patients was 47.65 ± 6.50 years. The average pain duration was 52.95 ± 34.81 weeks. A significantly greater decrease was detected in the VAS scores at 1 week (p = 0.036) and 1 month (p < 0.001) in Group 1 when compared to Group 2. Moreover, the proportion of patients with >50% improvement in the VAS scores at 1 week (p = 0.012) and 1 month (P = 0.017) was significantly lower in Group 1 than in Group 2.

DISCUSSION

SPG block appears as a safe, effective, and rapid method to treat PIFP, especially in cases with neuropathic pain. Neuropathic pain may be a predictor for pain relief in interventional procedures targeting SPG in the treatment of PIFP.

Sensory characteristics and chronic facial pain conditions: Cross-sectional study

OBJECTIVES

This study investigated patients with neuropathic, myofascial and other orofacial pain conditions according to the differences and similarities of the sensory profile, and the association between sensory findings and neuropathic or non-neuropathic conditions.

DESIGN

132 healthy controls were compared with 174 orofacial pain patients that were classified into three groups (neuropathic, masticatory myofascial and other orofacial pain condition) and evaluated with a systematized protocol of sensory testing. Data were analyzed with chi-quare and Bonferroni correction (categorical data), Student´s t test, oneway ANOVA, Tukey (quantitative features), Pearson´s coefficient for correlations and logistic regression.

RESULTS

Cold, olfactory and superficial pain thresholds were higher in the group of neuropathic facial pain compared with the other groups, and the highest vibratory thresholds were observed in the group of other orofacial pain conditions. Deep pain thresholds were statistically lower in the group with masticatory myofascial pain.

CONCLUSIONS

Positive sensory findings (eg. hyperalgesia) were more common in the group of patients with masticatory myofascial pain, supporting inflammatory systemic mechanisms, and negative sensory findings not restricted to the trigeminal nerve (eg. hypoesthesia, hyposmia) were more frequent in patients with neuropathic conditions. Non-classical neuropathic orofacial pains also showed sensory impairment from pain chronification and from the overlap with functional disorders.

Neuropathic orofacial pain: Characterization of different patient groups using the ICOP first edition, in a tertiary level Orofacial Pain Clinic

OBJECTIVE

To characterize patients with chronic neuropathic orofacial pain in accordance with the International Classification of Orofacial Pain (ICOP first edition) criteria.

STUDY DESIGN

A retrospective chart review of 108 patients was conducted. The most common categories observed were trigeminal neuralgia (TN) (25.9%), burning mouth syndrome (BMS) (11.1%), persistent idiopathic facial pain (PIFP) (26.9%), and posttraumatic trigeminal neuropathic pain (PTTNP) (26.9%); 9.3% of patients could not be categorized.

RESULTS

TN and BMS was more prevalent in the sixth decade, and PIFP and PTTN were more prevalent in the fifth decade. All categories showed female predilection. The pain in TN was predominantly episodic, described as "sharp shooting" and like an "electric shock," unilateral and affecting the V2 division, and with trigger zones in 50% of patients. Pain in BMS was predominantly constant and described as "burning," with the tongue being the most common site. Pain in PIFP and PTTNP was as follows: varied from constant to episodic; described as "burning," "sharp shooting," "throbbing," or "dull aching"; intraoral or extraoral; and mostly involving the V2 or V3 division.

CONCLUSION

This study is the first to characterize patients with neuropathic orofacial pain using the new ICOP criteria. PIFP and PTTNP were most commonly misdiagnosed categories. Using diagnostic criteria will increase the understanding of this patient group.

Altered trigeminal pain processing on brainstem level in persistent idiopathic facial pain

ABSTRACT

Persistent idiopathic facial pain (PIFP) is a poorly understood chronic pain syndrome of the face, formerly known as atypical facial pain. It is characterized by a constant painful sensation without neurological abnormalities and without clinically objectifiable cause. Similarities to neuropathic pain conditions have been discussed and are currently thought to be relevant for the pathophysiology of this disease. In this study, we aim to characterize the trigeminal pain processing in PIFP using functional magnetic resonance imaging of the brainstem. Twenty-five patients suffering from PIFP and 25 healthy controls underwent a standardized and well-established paradigm of painful stimulation of the trigeminal nerve using gaseous ammonia. Functional images were acquired within a 3T magnetic resonance imaging scanner using an optimized protocol for high-resolution echo planar brainstem imaging. Patients with PIFP show exclusively a stronger activation to painful stimulation in the spinal trigeminal nucleus when contrasted against healthy controls. Our data suggest that abnormal central pain processing plays a role in the pathophysiology of PIFP. An integration of these findings into neuropathic pain models might help to gain a better general understanding of the pathophysiology of PIFP.

Challenges of Misdiagnosis and Suboptimal Treatment of Persistent Idiopathic Facial Pain and Atypical Odontalgia: A Retrospective Multi-Centric Cross-Sectional Investigation

Purpose

To explore the challenges faced in the diagnosis and treatment of atypical odontalgia (AO) and other persistent idiopathic facial pain (PIFP).

Patients and Methods

This retrospective multi-centric cross-sectional study utilized clinical information (eg, clinical manifestations, history of consultations and treatments prior to correct diagnoses) from patients’ medical records. Their economic parameters were also extracted from medical insurance databases. Each variable collected was statistically analyzed. Differences of variables between AO and other PIFP were statistically tested.

Results

A total of 394 patients were included in this study. On average, the diagnostic delay was 34.8±14.2 months, a median of 7 consultations were performed prior to a correct diagnosis, and 5 ineffective prescriptions were issued. Patients with AO suffered from longer diagnostic delays than patients with other PIFP (38.4±14.3 months vs 31.6±13.4 months) and were more likely to receive invasive dental treatments (73.3% vs 4.3%). The median total cost of treatment for a single patient before correct diagnosis was 8506.3 yuan. Patients with AO spent more than patients with other PIFP (10,146.5 Yuan vs 3864.0 Yuan).

Conclusion

Patients with PIFP were frequently misdiagnosed and the length of diagnostic delay was observed to be long. Ineffective medications, unwarranted procedures, and unnecessary economic burden were imposed on the patients. Patients with AO are in a worse situation than patients with other PIFP. As significantly urgent and unsatisfactory results of misdiagnosis of PIFP have been reported in our study, more attention should be paid on the research and education in this field.

The fifth cranial nerve in headaches

The fifth cranial nerve is the common denominator for many headaches and facial pain pathologies currently known. Projecting from the trigeminal ganglion, in a bipolar manner, it connects to the brainstem and supplies various parts of the head and face with sensory innervation. In this review, we describe the neuroanatomical structures and pathways implicated in the sensation of the trigeminal system. Furthermore, we present the current understanding of several primary headaches, painful neuropathies and their pharmacological treatments. We hope that this overview can elucidate the complex field of headache pathologies, and their link to the trigeminal nerve, to a broader field of young scientists.

Differential Diagnosis of Chronic Neuropathic Orofacial Pain: Role of Clinical Neurophysiology

Orofacial pain syndromes encompass several clinically defined and classified entities. The focus here is on the role of clinical neurophysiologic and psychophysical tests in the diagnosis, differential diagnosis, and pathophysiological mechanisms of definite trigeminal neuropathic pain and other chronic orofacial pain conditions (excluding headache and temporomandibular disorders). The International Classification of Headache Disorders 2018 classifies these facial pain disorders under the heading Painful cranial neuropathies and other facial pains. In addition to unambiguous painful posttraumatic or postherpetic trigeminal neuropathies, burning mouth syndrome, persistent idiopathic facial and dental pain, and trigeminal neuralgia have also been identified with neurophysiologic and quantitative sensory testing to involve the nervous system. Despite normal clinical examination, these all include clusters of patients with evidence for either peripheral or central nervous system pathology compatible with the subclinical end of a continuum of trigeminal neuropathic pain conditions. Useful tests in the diagnostic process include electroneuromyography with specific needle, neurography techniques for the inferior alveolar and infraorbital nerves, brain stem reflex recordings (blink reflex with stimulation of the supraorbital, infraorbital, mental, and lingual nerves; jaw jerk; masseter silent period), evoked potential recordings, and quantitative sensory testing. Habituation of the blink reflex and evoked potential responses to repeated stimuli evaluate top-down inhibition, and navigated transcranial magnetic stimulation allows the mapping of reorganization within the motor cortex in chronic neuropathic pain. With systematic use of neurophysiologic and quantitative sensory testing, many of the current ambiguities in the diagnosis, classification, and understanding of chronic orofacial syndromes can be clarified for clinical practice and future research.

Alterations in grey matter density and functional connectivity in trigeminal neuropathic pain and trigeminal neuralgia: A systematic review and meta-analysis

•

Activation likelihood estimation (ALE) shows to be a verified method to meta-analyze heterogeneous imaging results.

•

From a broad variety of key regions, structural and functional changes were repeatedly found in the thalamus, the cingulate cortex and the middle frontal gyrus in TN/TNP patients.

•

Future research should focus on these regions of interest in order to improve diagnostic imaging in TN/TNP.

Background

Various studies reported changes in grey matter volumes and modifications in functional connectivity of cortical and subcortical structures in patients suffering from trigeminal neuralgia (TN) and trigeminal neuropathic pain (TNP). This study meta-analyzed the concordant structural and functional changes in foci and provide further understanding of the anatomy and biology of TN/TNP.

Methods

Relevant articles on magnetic resonance imaging (MRI) and functional MRI in TN/TNP, published before August 2018, were searched for on PubMed and Embase. Following exclusion of unsuitable studies, a meta-analysis was performed using activation likelihood estimation (ALE).

Results

In total, 322 paper were identified, 11 of which could be included based on the predefined inclusion and exclusion criteria. Eight papers, totaling 279 subjects, discussing structural changes and four papers, totaling 102 subjects, discussing functional changes were included (i.e., one paper investigated both structural and functional alterations). ALE analysis showed that in TN/TNP, grey matter decreases are found in the thalamus, (anterior) cingulate gyrus, bilateral striatum, the superior-, middle- and transverse temporal gyrus, subcallosal gyrus, the bilateral insular cortex, the pre- and postcental gyrus, the middle frontal gyrus bilaterally and the anterior cerebellar lobe. Grey matter increases were seen in the periaqueductal grey (PAG). Increased resting state functional organization was found within the bilateral middle- and superior frontal gyri, the (posterior) cingulate cortex and the thalamus/pulvinar.

Conclusions

Structural and functional changes meta-analyzed in this paper may contribute to elucidating the central pathophysiological mechanisms involved in TN/TNP. These results may be used as biomarkers to predict the response to medication and, ideally, in the future to offer personalized treatments.

Neuropathic Characteristics In Patients With Persistent Idiopathic Facial Pain

Background

Persistent idiopathic facial pain (PIFP) is a subtype of painful cranial neuropathies and other facial pains. The involvement of neuropathic mechanisms in PIFP, however, remains controversial. Using the Douleur Neuropathique 4 (DN4) questionnaire, the present study examined neuropathic characteristics in patients with PIFP.

Methods

The multi-institutional retrospective study collected the following clinical data from 205 consecutive patients with adult chronic pain: gender, age, BMI, diseases causing chronic pain, disease duration, visual analogue scale score of pain strength, and DN4 score. To compare neuropathic characteristics between PIFP and postherpetic neuralgia (PHN), we selected patients with PIFP (n=19) and patients with PHN (n=33), and performing a case-control study in which each patient with PHN or PIFP was matched by age and gender (n=16 in each group).

Results

DN4 score was significantly lower in the PIFP group than in the PHN group before and after matching. The incidence when DN4 was ≥4 was 10.5% before matching and 12.5% after matching in the PIFP group, both of which were significantly lower than those in the PHN group before and after matching (66.7% and 75.0%).

Conclusion

Ten percent of the PIFP patients likely show neuropathic pain characteristics.

Diagnostic delay and suboptimal management in persistent idiopathic facial pain and persistent dentoalveolar pain; a cross-sectional study

OBJECTIVES

The aim of this study was to explore the diagnostic and therapeutic challenges encountered by patients with persistent idiopathic facial pain (PIFP) and to investigate factors influencing its delayed diagnosis.

STUDY DESIGN

In this cross-sectional study, 34 patients with newly diagnosed PIFP were interviewed. Data about diagnostic delay, number and nature of previous consultations, and previous medical and surgical interventions were recorded. Pearson's correlation and Student t test were used to examine the differences among the variables in relation to diagnostic delay.

RESULTS

The average time between the onset of symptoms to correct diagnosis was 19.3 ± 11.1 months. Diagnostic delay was significantly longer in patient with pain localized to intraoral sites (22.6 ± 7.4) compared with patients with extraoral pain (16.1 ± 9.3). The average number of health care professionals consulted before correct diagnosis was 3.7 ± 2.3. General dental practitioners were the most commonly consulted health care professionals (n = 27; 79.4%). On average, patients were given 2.3 ± 0.24 misdiagnoses before the correct diagnosis was determined and were prescribed 3.5 ± 2.4 classes of drugs. Twenty-five patients (73.5%) underwent unnecessary surgical/dental interventions.

CONCLUSIONS

Patients with PIFP are frequently misdiagnosed, leading to prescription of ineffective medications and unnecessary investigations and surgical interventions. Educational efforts should emphasize on improving knowledge and awareness of this condition.

Neuropathic Orofacial Pain

Neuropathic pain of the orofacial region can cause much distress in individuals presenting with this condition. It may be easily mistaken for dental pain, and hence many individuals may undergo unnecessary dental work. Knowledge of the types of neuropathic orofacial pain may assist in timely diagnosis and improvement of a patient's quality of life.

Neurological Assessment Using a Quantitative Sensory Test in Patients with Chronic Unilateral Orofacial Pain

Background:

Quantitative Sensory Testing (QST) has been used in clinical and experimental settings to establish sensory assessment for different types of pains, and may be a useful tool for the assessment of orofacial pain, but this premise needs to be tested.

Objective:

The aim of the study was to evaluate responses to thermal stimuli between painful and non-painful facial sites in subjects with orofacial pain using QST.

Methods:

A total of 60 participants (5o females: 28-83 years; 10 males: 44-81 years) with unilateral orofacial pain were recruited from the Orofacial Pain Clinic at the Pain Management and Research Centre, Royal North Shore Hospital, Sydney, Australia. The study followed the methods of limits of the German Research Network testing four modalities of thermal thresholds, the Warm Sensation, the Cold Sensation, the Heat Pain and the Cold Pain using a TSA-II Neurosensory Analyser. The results were compared to the results from the unaffected side of the same patient on the same area and a single t test statistical analysis was performed, where a p value of less than 0.05 was considered significant.

Results:

The Mean Difference for Cold Sensation between the pain side and the non-pain side was 0.48 °C ± 1.5 (t= 2.466, p=0.017), 0.68 °C ± 2.04 for Warm Sensation (t= -2.573, p= 0.013), 2.56 °C ± 2.74 for Cold Pain (t= 7.238, p<0.001) and -1.21 °C ± 2.59 for Hot Pain (t= -3.639, p=0.001).

Conclusion:

The study showed that QST methods using thermal stimuli could be used to evaluate sensory dysfunction in orofacial pain patients using the specific parameters of cool and warm sensation, and cold and hot pain.

Defensive reflexes in people with pain – a biomarker of the need to protect? A meta-analytical systematic review

Upregulation of defensive reflexes such as the nociceptive flexion reflex (NFR) has been attributed to sensitisation of peripheral and spinal nociceptors and is often considered biomarkers of pain. Experimental modulation of defensive reflexes raises the possibility that they might be better conceptualised as markers of descending cognitive control. Despite strongly held views on both sides and several narrative reviews, there has been no attempt to evaluate the evidence in a systematic manner. We undertook a meta-analytical systematic review of the extant English-language literature from inception. Thirty-six studies satisfied our a priori criteria. Seventeen were included in the meta-analysis. Reflexive threshold was lower in people with clinical pain than it was in pain-free controls, but reflex size, latency, and duration were unaffected. The pattern of difference was not consistent with sensitisation of nociceptive neurones, as these changes were not isolated to the affected body part but was more consistent with top-down cognitive control reflective of heightened protection of body tissue. The pattern of modulation is dependent on potentially complex evaluative mechanisms. We offer recommendations for future investigations and suggest that defensive reflex threshold may reflect a biomarker of a broader psychological construct related to bodily protection, rather than sensitisation of primary nociceptors, spinal nociceptors, or pain.

Persistent idiopathic facial pain

Background

Persistent idiopathic facial pain (PIFP) is a chronic disorder recurring daily for more than two hours per day over more than three months, in the absence of clinical neurological deficit. PIFP is the current terminology for Atypical Facial Pain and is characterized by daily or near daily pain that is initially confined but may subsequently spread. Pain cannot be attributed to any pathological process, although traumatic neuropathic mechanisms are suspected. When present intraorally, PIFP has been termed ‘Atypical Odontalgia’, and this entity is discussed in a separate article in this special issue. PIFP is often a difficult but important differential diagnosis among chronic facial pain syndromes.

Aim

To summarize current knowledge on diagnostic criteria, differential diagnosis, pathophysiology and management of PIFP.

Methods

We present a narrative review reporting current literature and personal experience. Additionally, we discuss and differentiate the common differential diagnoses associated with PIFP including traumatic trigeminal neuropathies, regional myofascial pain, atypical neurovascular pains and atypical trigeminal neuropathic pains.

Results and conclusion

The underlying pathophysiology in PIFP is still enigmatic, however neuropathic mechanisms may be relevant. PIFP needs interdisciplinary collaboration to rule out and manage secondary causes, psychiatric comorbidities and other facial pain syndromes, particularly trigeminal neuralgia. Burden of disease and psychiatric comorbidity screening is recommended at an early stage of disease, and should be addressed in the management plan. Future research is needed to establish clear diagnostic criteria and treatment strategies based on clinical findings and individual pathophysiology.

Persistent idiopathic facial pain – a prospective systematic study of clinical characteristics and neuroanatomical findings at 3.0 Tesla MRI

Introduction

Persistent idiopathic facial pain (PIFP) is a poorly understood chronic orofacial pain disorder and a differential diagnosis to trigeminal neuralgia. To address the lack of systematic studies in PIFP we here report clinical characteristics and neuroimaging findings in PIFP.

Methods

Data collection was prospective and standardized in consecutive PIFP patients. All patients underwent 3.0 MRI.

Results

In a cohort of 53 PIFP patients, the average age of onset was 44.1 years. PIFP was found in more women 40 (75%) than men 13 (25%), p < 0.001. There was a high prevalence of bilateral pain 7 (13%), hypoesthesia 23 (48%), depression 16 (30%) and other chronic pain conditions 17 (32%) and a low prevalence of stabbing pain 21 (40%), touch-evoked pain 14 (26%) and remission periods 10 (19%). The odds ratio between neurovascular contact and the painful side was 1.4 (95% Cl 0.4–4.4, p = 0.565) and the odds ratio between neurovascular contact with displacement of the trigeminal nerve and the painful side was 0.2 (95% Cl 0.0–2.1, p = 0.195).

Conclusion

PIFP is separated from trigeminal neuralgia both with respect to the clinical characteristics and neuroimaging findings, as NVC was not associated to PIFP.

[Quantitative Sensory Testing in the facial area: a review]

Quantitative Sensory Testing is an established method to evaluate somatosensory function. In the facial area, the procedures depend on the localisation of disorders and the modalities of interest. The test stimuli are of thermal or mechanical nature (touch, pain, vibration, or pressure stimuli). According to the protocol of the German Neuropathic Pain Network, comprehensive information on the function of afferent nerves can be generated in the facial area as well. Standard values have been obtained for the cheek and intraoral mucosa. For various orofacial pain conditions, studies concerning the somatosensory function are available. Changed functional patterns are not limited to neuropathic pain, but also occur in other orofacial pain conditions, indicating, for example, central sensitisation. The standardised collection of QST parameters may improve the understanding of the pathophysiology of orofacial pain and effect therapeutic approaches. Comprehensive studies may lead to the development of specific screenings that are feasible in a clinical setting.

Quantitative sensory testing in trigeminal traumatic neuropathic pain and persistent idiopathic facial pain

The objective of this article was to investigate, with a systematic protocol of quantitative sensory testing, patients with persistent idiopathic facial pain (PIFP) and others with trigeminal traumatic neuropathic pain (TTN) compared to controls. Thirty patients with PIFP, 19 with TTN, and 30 controls were evaluated on subjective numbness and dysesthesia and with a systematic protocol of quantitative sensory testing for thermal evaluation (cold and warm), mechanical detection (touch and pinpricks for mechanical pain), superficial pain thresholds, and corneal reflex. We found that PIFP and TTN had numbness and dysesthesia higher than controls (p<0.001 and p=0.003), and that in both of them mechanical pain by pinpricks detection was abnormal intra and extra orally at the mandibular branch (p<0.001). Cold, warm, and tactile detections and pain thresholds were similar among the groups. Corneal reflex was abnormal in TTN (p=0.005). This study supports neuropathic mechanisms involving pain processing in PIFP and that the criterion on absence of sensorial variations in PIFP should be revised.

Occipital nerve block is effective in craniofacial neuralgias but not in idiopathic persistent facial pain

Occipital nerve block (ONB) has been used in several primary headache syndromes with good results. Information on its effects in facial pain is sparse. In this chart review, the efficacy of ONB using lidocaine and dexamethasone was evaluated in 20 patients with craniofacial pain syndromes comprising 8 patients with trigeminal neuralgia, 6 with trigeminal neuropathic pain, 5 with persistent idiopathic facial pain and 1 with occipital neuralgia. Response was defined as an at least 50% reduction of original pain. Mean response rate was 55% with greatest efficacy in trigeminal (75%) and occipital neuralgia (100%) and less efficacy in trigeminal neuropathic pain (50%) and persistent idiopathic facial pain (20%). The effects lasted for an average of 27 days with sustained benefits for 69, 77 and 107 days in three patients. Side effects were reported in 50%, albeit transient and mild in nature. ONBs are effective in trigeminal pain involving the second and third branch and seem to be most effective in craniofacial neuralgias. They should be considered in facial pain before more invasive approaches, such as thermocoagulation or vascular decompression, are performed, given that side effects are mild and the procedure is minimally invasive.

Buprenorphine injection to the stellate ganglion in the treatment of upper body chronic pain syndromes

BACKGROUND

The injection of low dose buprenorphine to the sympathetic ganglia, termed "GLOA", Ganglionide Local Opioid Analgesia, is used to treat chronic pain in several European centres. It is not known whether the clinically observed GLOA effect in chronic pain syndromes is due to a specific effect of buprenorphine at the ganglia. We assessed whether GLOA, plus intramuscular saline, was more efficacious than the reverse, saline injection to the stellate plus intramuscular buprenorphine, termed SSB.

METHODS

We devised a randomized, double-blinded, controlled crossover trial to treat patients with chronic upper body pain syndromes. Patients first received either GLOA or SSB. Pain was assessed using pain diaries both before injection and over the first 8h and 6days afterwards, and was expressed as relative pain intensity post versus pre-injection pain.

RESULTS

The median relative pain intensity after injections did not differ between GLOA and SSB. Four patients reported a low, <50%, relative pain level over the first 8h after SSB only. Four patients did not complete the trial and were excluded. One patient with cardiomyopathy became acutely diaphoretic and fatigued after GLOA, his vital signs however remained stable.

CONCLUSIONS

We failed to show a superiority of GLOA over SSB. Our results suggest it unlikely that the clinically observed effect after a single GLOA injection is due to a specific action of buprenorphine at the stellate ganglion. The efficacy of GLOA is hereby questioned. The use of GLOA in patients with cardiomyopathy should be cautioned.

TRIAL REGISTRATION

ISRCTN59287260; http://www.controlled-trials.com/

Psychiatric (axis I) and personality (axis II) disorders in patients with burning mouth syndrome or atypical facial pain

Background and aims

Burning mouth syndrome (BMS) and atypical facial pain (AFP) are often persistent idiopathic pain conditions that mainly affect middle-aged and elderly women. They have both been associated with various psychiatric disorders. This study examined current and lifetime prevalence of psychiatric axis I (symptom-based) and II (personality) disorders in patients with chronic idiopathic orofacial pain, and investigated the temporal relationship of psychiatric disorders and the onset of orofacial pain.

Method

Forty patients with BMS and 23 patients with AFP were recruited from Turku university hospital clinics. Mean age of the patients was 62.3 years (range 35–84) and 90% were female. BMS and AFP diagnoses were based on thorough clinical evaluation, and all patients had undergone clinical neurophysiological investigations including blink reflex and thermal quantitative tests. Current and lifetime DSM-IV diagnoses of axis I and II disorders were made on clinical basis with the aid of SCID-I and II-interviews. The detected prevalence rates and their 95% confidence intervals based on binomial distribution were compared to three previous large population-based studies.

Results

Of the 63 patients, 26 (41.3%) had had an axis I disorder that preceded the onset of orofacial pain, and 33 (52.4%) had had a lifetime axis I disorder. Rate of current axis I disorders was 36.5%, indicating that only about 16% of lifetime disorders had remitted, and they tended to run chronic course. The most common lifetime axis I disorders were major depression (30.2%), social phobia (15.9%), specific phobia (11.1%), and panic disorder (7.9%). Twelve patients (19.0%) had at least one cluster C personality disorder already before the emergence of orofacial pain. Patients with cluster C personality disorders are characterized as fearful and neurotic. None of the patients had cluster A (characterized as odd and eccentric) or B (characterized as dramatic, emotional or erratic) personality disorders. The most common personality disorders were obsessive–compulsive personality (14.3%), dependent personality (4.8%), and avoidant personality (3.2%). The majority of the patients (54%) had also one or more chronic pain conditions other than orofacial pain. In almost all patients (94%) they were already present at the onset of orofacial pain.

Conclusions

Our results suggest that major depression, persistent social phobia, and neurotic, fearful, and obsessive–compulsive personality characteristics are common in patients with chronic idiopathic orofacial pain. Most psychiatric disorders precede the onset of orofacial pain and they tend to run a chronic course.

Implications

We propose that the high psychiatric morbidity, and comorbidity to other chronic pain conditions, in chronic idiopathic orofacial pain can be best understood in terms of shared vulnerability to both chronic pain and specific psychiatric disorders, most likely mediated by dysfunctional brain dopamine activity.

Guidelines and recommendations for assessment of somatosensory function in oro-facial pain conditions--a taskforce report

The goals of an international taskforce on somatosensory testing established by the Special Interest Group of Oro-facial Pain (SIG-OFP) under the International Association for the Study of Pain (IASP) were to (i) review the literature concerning assessment of somatosensory function in the oro-facial region in terms of techniques and test performance, (ii) provide guidelines for comprehensive and screening examination procedures, and (iii) give recommendations for future development of somatosensory testing specifically in the oro-facial region. Numerous qualitative and quantitative psychophysical techniques have been proposed and used in the description of oro-facial somatosensory function. The selection of technique includes time considerations because the most reliable and accurate methods require multiple repetitions of stimuli. Multiple-stimulus modalities (mechanical, thermal, electrical, chemical) have been applied to study oro-facial somatosensory function. A battery of different test stimuli is needed to obtain comprehensive information about the functional integrity of the various types of afferent nerve fibres. Based on the available literature, the German Neuropathic Pain Network test battery appears suitable for the study of somatosensory function within the oro-facial area as it is based on a wide variety of both qualitative and quantitative assessments of all cutaneous somatosensory modalities. Furthermore, these protocols have been thoroughly described and tested on multiple sites including the facial skin and intra-oral mucosa. Standardisation of both comprehensive and screening examination techniques is likely to improve the diagnostic accuracy and facilitate the understanding of neural mechanisms and somatosensory changes in different oro-facial pain conditions and may help to guide management.

Evidence-based interventional pain medicine according to clinical diagnoses. 3. Persistent idiopathic facial pain

Persistent idiopathic facial pain, previously known as atypical facial pain, is described as a persistent facial pain that does not have the classical characteristics of cranial neuralgias and for which there is no obvious cause (International Classification of Headache Disorders in 2004). According to these criteria, the diagnosis is possible if the facial pain is localized, present daily, and throughout all or most of the day. By definition, neurological and physical examination findings in persistent idiopathic facial pain should be normal. Forming a diagnosis is not simple and follows a process of elimination of other causes of facial pain. The precise incidence is unknown. The affliction is seen primarily in older adults and rarely in children. The pathophysiology is unknown. In persistent idiopathic facial pain, there is no abnormal processing of somatosensory stimuli in the pain area or facial area of the primary somatosensory cortex of the brain. The treatment is difficult and often requires a multidisciplinary approach. The most important part of the treatment is psychological counseling and pharmacological therapy. Pharmacological treatment with tricyclic antidepressants and anti-epileptic drugs can be tried. The conservative, pharmacological treatment with amitryptiline is the primary choice. Venlafaxine and fluoxetine treatment can also be considered. When the pharmacological treatment fails, pulsed radiofrequency treatment of the ganglion pterygopalatinum (sphenopalatinum) can be considered (2 C+).

Differential effect of intravenous S -ketamine and fentanyl on atypical odontalgia and capsaicin-evoked pain

Atypical odontalgia (AO) is an intraoral pain condition of currently unknown mechanisms. In 10 AO patients and 10 matched healthy controls, we examined the effect of intravenous infusion of an N-methyl-D-aspartate (NMDA) receptor antagonist S-ketamine and a mu-opioid agonist fentanyl on spontaneous AO pain and on an acute intraoral nociceptive input evoked by topical application of capsaicin. The drugs were administered in a randomized, placebo-controlled, cross-over manner. Furthermore, measures of intraoral sensitivity to mechanical and thermal quantitative sensory testing (QST) including temporal summation were compared between groups and sides. Both drugs failed to produce an analgesic effect on spontaneous AO pain, but fentanyl effectively reduced capsaicin-evoked pain. AO patients showed increased sensitivity to capsaicin and heat pain, but no significant differences in cold and mechanical sensitivity compared with healthy controls. No side-to-side differences in QST measures were found in AO patients. The present study demonstrates that AO is unlikely to be primarily due to a persistent afferent barrage from the peripheral region. Furthermore, in contrast to studies on various neuropathic pain conditions, fentanyl and S-ketamine in the present doses failed to attenuate AO pain.

Impaired thermal perception in cluster headache

Cluster headache is characterized by attacks of severe periorbital pain. Repetitive burst activity in afferent fibers may induce plastic alterations in somatosensory synaptic processing as a prerequisite for recurring and chronic pain. This psychophysical study addressed hypothesized dysfunctions in craniofacial somatosensory processing in cluster headache disease. Thermal and mechanical sensory functions in the periorbital region were assessed by quantitative sensory testing (QST) in 25 cluster headache patients and 60 healthy volunteers. Perception of warmth (p<0.01), cold (p<0.000001), and pressure pain (p<0.05) was reduced on the cluster side as compared with the contralateral asymptomatic side. In contrast to healthy volunteers, warm detection threshold (WDT) and thermal sensory limen (TSL) on one side did not positively correlate with the other side. WDT and TSL negatively correlated with the elapsed time since last attack. All patients showed QST abnormalities on the headache side in comparison to healthy controls. Loss of sensory functions strongly preponderated gain. Several lines of evidence indicate a pivotal role of the hypothalamus in cluster headache pathophysiology. The impairment of warm and cold perception in patients may be based upon a dysfunction of the hypothalamus which is strongly involved in thermosensory control.