Increased pain sensitivity is not a risk factor but a consequence of frequent headache: a population-based follow-up study

Alexithymia Increases Pericranial and Cervical Muscle Tenderness in Women with Migraine

Background/Objectives: Alexithymia is characterized by a deficit in identifying and communicating feelings. Emerging evidence suggests that alexithymia is highly prevalent in migraine, in a complex interplay with psychiatric comorbidity. Pericranial/cervical muscle tenderness is a remarkable clinical feature in a large proportion of migraine patients. This pilot study aimed at investigating the relationship between alexithymia and pericranial/cervical muscle tenderness in female migraineurs. Methods: A total of 42 female patients fulfilling the diagnostic criteria for migraine were enrolled into this pilot, observational, cross-sectional study after informed consent was obtained. Each patient underwent a psychological assessment to identify any alexithymia by means of TAS-20, anxiety/mood comorbidity (by means of STAI-Y1 STAI-Y2, BDI-II), and migraine-related disability (by means of HIT-6), and a physical cranial/cervical musculoskeletal examination. Palpation of pericranial and cervical muscles was carried out in the standardized manner. A Cumulative Muscle Tenderness (CUM) score (0-6) was calculated for each patient. A multivariate analysis was performed to investigate any association amongst the TAS-20 score, the CUM score, and the following covariates: BDI-II, STAI-Y1, STAI-Y2, and HIT-6 scores, age, disease duration, monthly migraine days, and average head pain intensity in the previous three months. Results: Overall, 35.6% of the sample had alexithymia. The multivariate analysis detected a linear and independent relationship between the TAS-20 and CUM scores, with a statistically significant (p = 0.017) association. Conclusions: This pilot study suggests that alexithymia plays a role in increasing pericranial/cervical muscle tenderness in migraine, independently from psychiatric comorbidity. A novel therapeutical approach, targeting alexithymia, may well reduce muscular tenderness in female migraineurs.

Research Progress on the Experimental Model and Underlying Mechanistic Studies of Tension-Type Headaches

PURPOSE OF REVIEW

Tension-type headaches (TTH) significantly diminish patients' quality of life and increase absenteeism, thereby imposing a substantial economic burden. Animal models are essential tools for studying disease mechanisms and drug development. However, until now, little focus has been placed on summarizing the animal models of TTH and associated mechanistic studies. This narrative review discusses the current animal models of TTH and related mechanistic studies to provide insights into the pathophysiological mechanisms of and treatments for TTH.

RECENT FINDINGS

The primary method for constructing an animal model of TTH involves injecting a solution of pain relievers, such as adenosine triphosphate, nerve growth factor, or a high concentration of salt solution, into the neck to initiate harmful cervical muscle responses. This model enables the examination of the interaction between peripheral muscles and central sensitization, which is crucial for understanding the pathophysiology of TTH. Mechanistic studies based on this model have investigated the effect of the P2X receptor antagonist, P2X7 receptor blockade, the P2Y1 receptor agonist 2-MESADP, P2Y1 receptor antagonist MRS2179, nitric oxide synthase inhibitors, and acetylsalicylic acid. Despite notable advancements, the current model of TTH has limitations, including surgical complexity and the inability to replicate chronic tension-type headache (CTTH). To gain a more comprehensive understanding and develop more effective treatment methods, future studies should focus on simplifying surgical procedures, examining other predisposing factors, and establishing a model for chronic TTH. This will offer a deeper insight into the pathophysiological mechanism of TTH and pave the way for improved treatment approaches.

Does Tension Headache Have a Central or Peripheral Origin? Current State of Affairs

PURPOSE OF REVIEW

The aim of this narrative review is to analyze the evidence about a peripheral or central origin of a tension headache attack in order to provide a further clarification for an appropriate approach.

RECENT FINDINGS

Tension headache is a complex and multifactorial pathology, in which both peripheral and central factors could play an important role in the initiation of an attack. Although the exact origin of a tension headache attack has not been conclusively established, correlations have been identified between certain structural parameters of the craniomandibular region and craniocervical muscle activity. Future research should focus on improving our understanding of the pathology with the ultimate goal of improving diagnosis. The pathogenesis of tension-type headache involves both central and peripheral mechanisms, being the perpetuation over time of the headache attacks what would favor the evolution of an episodic tension-type headache to a chronic tension-type headache. The unresolved question is what factors would be involved in the initial activation in a tension headache attack. The evidence that favors a peripheral origin of the tension headache attacks, that is, the initial events occur outside the brain barrier, which suggests the action of vascular and musculoskeletal factors at the beginning of a tension headache attack, factors that would favor the sensitization of the peripheral nervous system as a result of sustained sensory input.

The cervical spine in tension type headache

INTRODUCTION

The concept that headaches may originate in the cervical spine has been discussed over decades and is still a matter of debate. The cervical spine has been traditionally linked to cervicogenic headache; however, current evidence supports the presence of cervical musculoskeletal dysfunctions also in tension-type headache.

PURPOSE

This position paper discusses the most updated clinical and evidence-based data about the cervical spine in tension-type headache.

IMPLICATIONS

Subjects with tension-type headache exhibit concomitant neck pain, cervical spine sensitivity, forward head posture, limited cervical range of motion, positive flexion-rotation test and also cervical motor control disturbances. In addition, the referred pain elicited by manual examination of the upper cervical joints and muscle trigger points reproduces the pain pattern in tension-type headache. Current data supports that the cervical spine can be also involved in tension-type headache, and not just in cervicogenic headache. Several physical therapies including upper cervical spine mobilization or manipulation, soft tissue interventions (including dry needling) and exercises targeting the cervical spine are proposed for managing tension-type headache; however, the effectiveness of these interventions depends on a proper clinical reasoning since not all will be equally effective for all individuals with tension-type headache. Based on current evidence, we propose to use the terms cervical "component" and cervical "source" when discussing about headache. In such a scenario, in cervicogenic headache the neck can be the cause (source) of the headache whereas in tension-type headache the neck will have a component on the pain pattern, but it will be not the cause since it is a primary headache.

Debate: differences and similarities between tension-type headache and migraine

Tension-type headache (TTH) and migraine are two common primary headaches distinguished by clinical characteristics according to the 3^rd edition of the International Classification of Headache Disorders. Migraine is identified by specific features such as being more prevalent in females, being aggravated by physical activity, certain genetic factors, having photophobia, phonophobia, nausea, vomiting, or aura, and responding to specific drugs. Nonetheless, TTH and migraine share some common characteristics, such as onset occurring in the 20 s, and being triggered by psychological factors like stress, moderate pain severity, and mild nausea in chronic TTH. Both conditions involve the trigeminovascular system in their pathophysiology. However, distinguishing between TTH and migraine in clinical practice, research, and epidemiological studies can be challenging, as there is a lack of specific diagnostic tests and biomarkers. Moreover, both conditions may coexist, further complicating the diagnostic process. This review aims to explore the similarities and differences in the pathophysiology, epidemiology, burden and disability, comorbidities, and responses to pharmacological and non-pharmacological treatments of TTH and migraine. The review also discusses future research directions to address the diagnostic challenges and improve the understanding and management of these conditions.

Headache caused by the use of personal protective equipment in healthcare workers during the COVID-19 pandemic period

Objective

Coronavirus 2019 disease (COVID-19), the cause of the ongoing pandemic, is an acute respiratory tract infection, which has made it necessary for healthcare personnel to use protective equipment such as N95 masks, protective goggles and visors. External compression headaches caused by the compression of the pericranial soft tissues by wearing hats, helmets, or goggles (worn during swimming or diving) have been previously described. In our study, we aimed to evaluate the presence and characteristics of personal protective equipment-associated headaches in healthcare workers during the COVID-19 pandemic period and to determine the effects of such headaches.

Materials and methods

A face-to-face questionnaire was delivered to 300 male and female healthcare personnel between the ages of 18-56 working in healthcare units where COVID-19 patients were evaluated and treated. The data from 296 completed questionnaires was evaluated.

Results

We included 296 participants (166 females and 130 males) in our study; the mean age was 33.98 ± 8.52 years (range 18-56). One hundred ninety-six (66.22%) participants indicated that they had new onset personal protective equipment-associated headaches. Percentages of those with newly emergent headaches because of protective equipment were higher in the following participant groups: females (p = 0.045), those with COVID-19 disease history (p < 0.001), and those diagnosed with headaches before the pandemic (p = 0.001).

Conclusion

Our study showed the presence of new-onset headaches associated with personal protective equipment in healthcare workers during the COVID-19 pandemic. Personal protective equipment-related headaches were associated with the following factors: female sex, a history of COVID-19 disease, and the presence of primary headaches diagnosed before the pandemic.

Pain sensitivity in relation to frequency of migraine and tension-type headache with or without coexistent neck pain: an exploratory secondary analysis of the population study

OBJECTIVES

We aimed to investigate whether coexistent self-reported neck pain influences cephalic and extracephalic pain sensitivity in individuals with migraine and tension-type headache (TTH) in relation to diagnosis and headache frequency.

METHODS

A population of 496 individuals completed a headache interview based on ICHD criteria, providing data collected by self-administered questionnaires, assessments of pericranial total tenderness score (TTS) and pressure pain thresholds (PPT). Stimulus-response (SR) functions for pressure vs. pain were recorded. Presence of neck pain in the past year was assessed by the self-administered questionnaire. We categorized participants by primary headache type. We also categorized participants into 3 groups by headache frequency: chronic (≥15) or episodic (<15 headache days/month) headache and controls. TTS, PPTs and the area under the SR curve were compared between subgroups using Generalized Linear Models with pairwise comparisons controlling for age and sex.

RESULTS

Individuals with chronic followed by episodic headache had higher TTS than controls (overall p≤0.001). The difference between chronic and episodic headache subgroups was significant in the group with neck pain (p≤0.001) but not in the group without neck pain. In individuals with neck pain, mean TTS was higher in coexistent headache (migraine and TTH), 23.2 ± 10.7, and pure TTH, 17.8 ± 10.3, compared to pure migraine, 15.9 ± 10.9 and no headache 11.0 ± 8.3 (overall p<0.001). Temporal and finger PPTs did not statistically differ among the chronic headache, the episodic headache and controls in individuals with and without neck pain. Temporalis and trapezius SR-functions showed that tenderness was increased in individuals with chronic headache to higher degree than in those with episodic headache, and more so in those with neck pain.

CONCLUSIONS

Coexistent neck pain is associated with greater pericranial tenderness in individuals with chronic headache and to a lesser degree in those with episodic headache. Sensitization may be a substrate or consequence of neck pain and primary headache, but a longitudinal study would be needed for further clarification.

Current Understanding of the Pathophysiology and Approach to Tension-Type Headache

PURPOSE OF REVIEW

Description of headache dates back thousands of years, and to date, tension-type headache (TTH) remains the most common form of headache. We will review the history and current understanding of the pathophysiology of TTH and discuss the recommended clinical evaluation and management for this syndrome.

RECENT FINDINGS

Despite being the most prevalent headache disorder, TTH pathophysiology remains poorly understood. Patients with TTH tend to have muscles that are harder, more tender to palpation, and may have more frequent trigger points of tenderness than patients without headache. However, cause and effect of these muscular findings are unclear. Studies support both peripheral and central mechanisms contributing to the pain of TTH. Diagnosis is based on clinical presentation, while the focus of evaluation is to rule out possible secondary causes of headache. Treatment options have remained similar over the course of the past decade, with some additional studies supportive of both pharmacological and non-pharmacological options. An approach to TTH has been outlined including historical context, evolution over time, and the best evidence regarding our current understanding of the complex pathophysiology and treatment of this disease.

Has the Phase of the Menstrual Cycle Been Considered in Studies Investigating Pressure Pain Sensitivity in Migraine and Tension-Type Headache: A Scoping Review

OBJECTIVE

The aim of this scoping review was to identify if the phase of the menstrual cycle was considered in observational studies comparing pressure pain sensitivity between women with migraine or tension-type headache (TTH) and headache-free women.

METHODS

A systematic electronic literature search in PubMed, Medline, Web of Science, Scopus, and CINAHL databases was conducted. Observational studies including one or more groups with TTH and/or migraine comparing pressure pain thresholds (PPTs) were included. The methodological quality (risk of bias) was assessed with the Newcastle-Ottawa Scale. Authors, objectives, inclusion/exclusion criteria, size sample, female sample, tool to assess PPTs, mean age, and the use of any medication were extracted and analyzed independently by two authors.

RESULTS

From a total of 1404 and 1832 identified articles for TTH and migraine, 30 and 18 studies satisfied the criteria and were included. Nineteen (63.4%) studies assessing TTH patients and eleven (61.1%) assessing migraine patients showed a high risk of bias. The most common flaws were attributed to improper selection of control and control over other additional factors. Based on the systematic review, just one study including TTH and one including migraine patients considered the menstrual cycle.

CONCLUSION

The results of this scoping review identified that the phase of the menstrual cycle has been rarely considered in studies investigating sensitivity to pressure pain in primary headaches, such as TTH or migraine, although there is evidence showing the relevance of the phase of the menstrual cycle in pain perception.

Does Quantitative Sensory Testing Improve Prediction of Chronic Pain Trajectories? A Longitudinal Study of Youth With Functional Abdominal Pain Participating in a Randomized Controlled Trial of Cognitive Behavioral Treatment

OBJECTIVES

Youth with functional abdominal pain (FAP) experience significant pain-related distress and functional impairment. Although quantitative sensory testing protocols have identified alterations in pain modulatory systems that distinguish youth with FAP from healthy controls, the extent to which evoked pain responses predict subsequent trajectories of pain symptoms and disability over and above established psychosocial risk factors is unclear.

METHODS

The present study included 183 adolescents with FAP who were enrolled in a randomized controlled trial comparing an 8-week, internet-delivered program of cognitive behavior therapy (n=90) or pain education (n=93). Participants completed a quantitative sensory testing protocol before the intervention and were followed for 12-month posttreatment.

RESULTS

Whereas adolescents with FAP who exhibited stronger baseline conditioned pain modulation (CPM) reported decreases in pain-related interference over follow-up (b=-0.858, SE=0.396, P=0.032), those with weaker CPM exhibited high, relatively stable levels of pain-related interference over time (b=-0.642, SE=0.400, P=0.110). CPM status predicted changes in pain-related interference after controlling for the effects of treatment condition and psychosocial risk factors. Static measures of pain sensitivity (ie, pain threshold, pain tolerance) and temporal summation of second pain were not associated with changes in measures of abdominal pain, gastrointestinal symptom severity, or pain-related interference over follow-up.

DISCUSSION

The present findings contribute to a growing literature on the predictive utility of quantitative sensory testing indices and suggest that CPM may complement existing psychosocial risk measures in determining individualized pain-related risk profiles.

Facemask headache: a new nosographic entity among healthcare providers in COVID-19 era

BACKGROUND

SARS-CoV-2 is a novel infectious agent causing coronavirus disease 2019, which has been declared as pandemic in March 2020. Personal protective equipment has been mandatory for healthcare workers in order to contain the outbreak of pandemic disease. Mild neurological disturbances such as headache have been related to the extensive utilization of facemask. This study aims to examine headache variations related to the intensive utilization of facemask among a cohort of healthcare professionals in a setting of low-medium risk of exposure to SARS-CoV-2.

METHODS

This is a cross-sectional study among healthcare providers from different hospital and clinics in Italy. Each participant completed a specifically designed self-administered questionnaire. Headache features and outcome measures' change from baseline were evaluated over a 4-month period, in which wearing facemask has become mandatory for Italian healthcare workers.

RESULTS

A total of 400 healthcare providers completed the questionnaire, 383 of them met the inclusion criteria. The majority were doctors, with a mean age of 33.4 ± 9.2 years old. Among 166/383 subjects, who were headache free at baseline, 44 (26.5%) developed de novo headache. Furthermore, 217/383 reported a previous diagnosis of primary headache disorder: 137 were affected by migraine and 80 had tension-type headache. A proportion (31.3%) of these primary headache sufferers experienced worsening of their pre-existing headache disorder, mainly for migraine frequency and attack mean duration.

CONCLUSIONS

Our data showed the appearance of de novo associated facemask headache in previous headache-free subjects and an exacerbation of pre-existing primary headache disorders, mostly experienced by people with migraine disease.

Tension-type headache

Tension-type headache (TTH) is the most prevalent neurological disorder worldwide and is characterized by recurrent headaches of mild to moderate intensity, bilateral location, pressing or tightening quality, and no aggravation by routine physical activity. Diagnosis is based on headache history and the exclusion of alternative diagnoses, with clinical criteria provided by the International Classification of Headache Disorders, third edition. Although the biological underpinnings remain unresolved, it seems likely that peripheral mechanisms are responsible for the genesis of pain in TTH, whereas central sensitization may be involved in transformation from episodic to chronic TTH. Pharmacological therapy is the mainstay of clinical management and can be divided into acute and preventive treatments. Simple analgesics have evidence-based effectiveness and are widely regarded as first-line medications for the acute treatment of TTH. Preventive treatment should be considered in individuals with frequent episodic and chronic TTH, and if simple analgesics are ineffective, poorly tolerated or contraindicated. Recommended preventive treatments include amitriptyline, venlafaxine and mirtazapine, as well as some selected non-pharmacological therapies. Despite the widespread prevalence and associated disability of TTH, little progress has been made since the early 2000s owing to a lack of attention and resource allocation by scientists, funding bodies and the pharmaceutical industry.

Interprofessional Collaboration in Dentistry: Role of physiotherapists to improve care and outcomes for chronic pain conditions and sleep disorders

Physiotherapists can manage chronic pain patients by using technical interventions such as mobility, strengthening, manual therapy, or flexibility in a specific and functional manner, being a key component of a multidisciplinary team. Dentists are involved in the management of different chronic pain conditions such as temporomandibular disorders and sleep disorders such as obstructive sleep apnea. However, they are frequently unaware of the benefits of collaborating with physical therapists. In this review, the collaboration of physical therapists and dentists will be explored when managing orofacial pain, headaches, and sleep disorders. The physical therapist is important in the management of these disorders and also in the screening of risk factors.

Quantitative assessment of nonpelvic pressure pain sensitivity in urologic chronic pelvic pain syndrome: a MAPP Research Network study

Experimental pain sensitivity was assessed in individuals with urologic chronic pelvic pain syndrome (UCPPS) as part of the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network. A series of computer-controlled pressure stimuli were delivered to the thumbnail bed, an asymptomatic site distant from the area of UCPPS pain that is considered to be indicative of overall body pain threshold. Stimuli were rated according to a standardized magnitude estimation protocol. Pain sensitivity in participants with UCPPS was compared with healthy controls and a mixed pain group composed of individuals with other chronic overlapping pain conditions, including fibromyalgia, chronic fatigue, and irritable bowel syndromes. Data from 6 participating MAPP testing sites were pooled for analysis. Participants with UCPPS (n = 153) exhibited an intermediate pain sensitivity phenotype: they were less sensitive relative to the mixed pain group (n = 35) but significantly more sensitive than healthy controls (n = 100). Increased pain sensitivity in patients with UCPPS was associated with both higher levels of clinical pain severity and more painful body areas outside the pelvic region. Exploratory analyses in participants with UCPPS revealed that pain sensitivity increased during periods of urologic symptom flare and that less pressure pain sensitivity at baseline was associated with a greater likelihood of subsequent genitourinary pain improvement 1 year later. The finding that individuals with UCPPS demonstrate nonpelvic pain hypersensitivity that is related to clinical symptoms suggests that central nervous system mechanisms of pain amplification contribute to UCPPS.

Quantitative sensory testing and predicting outcomes for musculoskeletal pain, disability, and negative affect: a systematic review and meta-analysis

Hypersensitivity due to central pain mechanisms can influence recovery and lead to worse clinical outcomes, but the ability of quantitative sensory testing (QST), an index of sensitisation, to predict outcomes in chronic musculoskeletal disorders remains unclear. We systematically reviewed the evidence for ability of QST to predict pain, disability, and negative affect using searches of CENTRAL, MEDLINE, EMBASE, AMED, CINAHL, and PubMed databases up to April 2018. Title screening, data extraction, and methodological quality assessments were performed independently by 2 reviewers. Associations were reported between baseline QST and outcomes using adjusted (β) and unadjusted (r) correlations. Of the 37 eligible studies (n = 3860 participants), 32 were prospective cohort studies and 5 randomised controlled trials. Pain was an outcome in 30 studies, disability in 11, and negative affect in 3. Meta-analysis revealed that baseline QST predicted musculoskeletal pain (mean r = 0.31, 95% confidence interval [CI]: 0.23-0.38, n = 1057 participants) and disability (mean r = 0.30, 95% CI: 0.19-0.40, n = 290 participants). Baseline modalities quantifying central mechanisms such as temporal summation and conditioned pain modulation were associated with follow-up pain (temporal summation: mean r = 0.37, 95% CI: 0.17-0.54; conditioned pain modulation: mean r = 0.36, 95% CI: 0.20-0.50), whereas baseline mechanical threshold modalities were predictive of follow-up disability (mean r = 0.25, 95% CI: 0.03-0.45). Quantitative sensory testing indices of pain hypersensitivity might help develop targeted interventions aiming to improve outcomes across a range of musculoskeletal conditions.

Tooth Clenching Induces Abnormal Cerebrovascular Responses in Migraineurs

Prevalence of masticatory parafunctions, such as tooth clenching and grinding, is higher among migraineurs than non-migraineurs, and masticatory dysfunctions may aggravate migraine. Migraine predisposes to cerebrovascular disturbances, possibly due to impaired autonomic vasoregulation, and sensitization of the trigeminovascular system. The relationships between clenching, migraine, and cerebral circulation are poorly understood. We used Near-Infrared Spectroscopy to investigate bilateral relative oxy- (%Δ[O₂Hb]), deoxy- (%Δ[HHb]), and total (%Δ[tHb]) hemoglobin concentration changes in prefrontal cortex induced by maximal tooth clenching in twelve headache-free migraineurs and fourteen control subjects. From the start of the test, migraineurs showed a greater relative increase in right-side %Δ[HHb] than controls, who showed varying reactions, and right-side increase in %Δ[tHb] was also greater in migraineurs (p < 0.001 and p < 0.05, respectively, time-group interactions, Linear mixed models). With multivariate regression model, migraine predicted the magnitude of maximal blood pressure increases, associated in migraineurs with mood scores and an intensity of both headache and painful signs of temporomandibular disorders (pTMD). Although changes in circulatory parameters predicted maximal NIRS responses, the between-group differences in the right-side NIRS findings remained significant after adjusting them for systolic blood pressure and heart rate. A family history of migraine, reported by all migraineurs and four controls, also predicted maximal increases in both %Δ[HHb] and %Δ[tHb]. Presence of pTMD, revealed in clinical oral examination in eight migraineurs and eight controls, was related to maximal %Δ[HHb] increase only in controls. To conclude, the greater prefrontal right-side increases in cerebral %Δ[HHb] and %Δ[tHb] may reflect disturbance of the tooth clenching-related cerebral (de)oxygenation based on impaired reactivity and abnormal microcirculation processes in migraineurs. This finding may have an impact in migraine pathophysiology and help to explain the deleterious effect of masticatory dysfunctions in migraine patients. However, the role of tooth clenching as a migraine trigger calls for further studies.

Effects of topical vs injection treatment of cervical myofascial trigger points on headache symptoms in migraine patients: a retrospective analysis

Background

In migraine patients with cervical myofascial trigger points whose target areas coincide with migraine sites (M + cTrPs), TrP anesthetic injection reduces migraine symptoms, but the procedure often causes discomfort. This study evaluated if a topical TrP treatment with 3% nimesulide gel has similar efficacy as the injection but produces lesser discomfort with higher acceptability by the patients.

Methods

Retrospective analysis of medical charts of M + cTrPs patients in the period January 2012–December 2016 at a single Headache Center. Three groups of 25 patients each were included, all receiving migraine prophylaxis (flunarizine 5 mg/day) for 3 months and symptomatic treatment on demand. Group 1 received no TrP treatment, group 2 received TrP injections (bupivacaine 5 mg/ml at basis, 3rd, 10th, 30th and 60th day), group 3 received daily TrP topical treatment with 1.5 g of 3% nimesulide gel for 15 consecutive days, 15 days interruption and again 15 consecutive days. The following were evaluated: monthly number of migraine attacks and rescue medications, migraine intensity; pain thresholds to skin electrical stimulation (EPTs) and muscle pressure stimulation (PPTs) in TrP and target (basis, 30th, 60th and 180th days); discomfort from, acceptability of and willingness to repeat treatment (end of study). ANOVA for repeated measures and 1-way ANOVA were used to assess temporal trends in each group and comparisons among groups, respectively. Significance level was set at p < 0.05.

Results

Migraine improved over time in all groups, but significantly more and earlier in those receiving TrP treatment vs no TrP treatment (0.02 < p < 0.0001, 30–180 days for intensity and rescue medication, 60–180 days for number). All thresholds in the non-TrP-treated group did not change over time, while significantly improving in both the injection and nimesulide gel groups (0.01 < p < 0.0001, 30–180 days). Improvement of migraine and thresholds did not differ in the two TrP-treated groups. Discomfort was significantly lower, acceptability and willingness to repeat treatment significantly higher (0.05 < p < 0.0001) with gel than injection.

Conclusion

In migraine patients, topical treatment of cervical TrPs with 5% nimesulide gel proves equally effective as TrP injection with local anesthetics but more acceptable by the patients. This treatment could be effectively associated to standard migraine prophylaxis to improve therapeutic outcomes.

Pain Perception and Migraine

Background: It is well-known that both inter- and intra-individual differences exist in the perception of pain; this is especially true in migraine, an elusive pain disorder of the head. Although electrophysiology and neuroimaging techniques have greatly contributed to a better understanding of the mechanisms involved in migraine during recent decades, the exact characteristics of pain threshold and pain intensity perception remain to be determined, and continue to be a matter of debate.

Objective: The aim of this review is to provide a comprehensive overview of clinical, electrophysiological, and functional neuroimaging studies investigating changes during various phases of the so-called “migraine cycle” and in different migraine phenotypes, using pain threshold and pain intensity perception assessments.

Methods: A systematic search for qualitative studies was conducted using search terms “migraine,” “pain,” “headache,” “temporal summation,” “quantitative sensory testing,” and “threshold,” alone and in combination (subject headings and keywords). The literature search was updated using the additional keywords “pain intensity,” and “neuroimaging” to identify full-text papers written in English and published in peer-reviewed journals, using PubMed and Google Scholar databases. In addition, we manually searched the reference lists of all research articles and review articles.

Conclusion: Consistent data indicate that pain threshold is lower during the ictal phase than during the interictal phase of migraine or healthy controls in response to pressure, cold and heat stimuli. There is evidence for preictal sub-allodynia, whereas interictal results are conflicting due to either reduced or no observed difference in pain threshold. On the other hand, despite methodological limitations, converging observations support the concept that migraine attacks may be characterized by an increased pain intensity perception, which normalizes between episodes. Nevertheless, future studies are required to longitudinally evaluate a large group of patients before and after pharmacological and non-pharmacological interventions to investigate phases of the migraine cycle, clinical parameters of disease severity and chronic medication usage.

Autonomic responses to tooth clenching in migraineurs-augmented trigeminocardiac reflex?

BACKGROUND

Systemic autonomic changes are well known in migraineurs. Also, masticatory disorders are reported to be associated with migraine. However, if those phenomena are interrelated, and how, is unclear. Moreover, the knowledge on the autonomic responses to masticatory stimuli in migraineurs is limited.

OBJECTIVE

To investigate tooth clenching-related cardiac autonomic regulation in migraineurs.

METHODS

We compared maximal tooth clenching-induced systemic autonomic responses, indicated by heart rate variability and blood pressure changes, in headache-free migraineurs (n = 17) and control subjects (n = 22).

RESULTS

Levels of high-frequency power, reflecting vagal activity, were lower in migraineurs at baseline but increased after tooth clenching whereas in controls they returned to baseline (P < 0.05, mixed model analysis). In multivariate regression model, the presence of migraine predicted the baseline levels of low- and high-frequency power and sympathovagal balance, and the post-test increase in high-frequency power, with the attack frequency and side of headache as the modifiers of the measured changes in migraineurs. The painful signs of temporomandibular disorders, found in clinical oral examination, enhanced both maximal changes in RR intervals and post-test vagal responses to tooth clenching only in migraineurs.

CONCLUSION

The enhanced post-clenching vagal activation may represent a marker of the augmented trigeminocardiac reflex to stimulation of trigeminal area, sensitised in migraineurs. Our results support an involvement of autonomic mechanisms in migraine pathophysiology and are interesting in terms of interactions between migraine and masticatory disorders, elucidating one potential way how masticatory disorders may aggravate migraine.

Lateralized kappa opioid receptor signaling from the amygdala central nucleus promotes stress-induced functional pain

The response of diffuse noxious inhibitory controls (DNIC) is often decreased, or lost, in stress-related functional pain syndromes. Because the dynorphin/kappa opioid receptor (KOR) pathway is activated by stress, we determined its role in DNIC using a model of stress-induced functional pain. Male, Sprague-Dawley rats were primed for 7 days with systemic morphine resulting in opioid-induced hyperalgesia. Fourteen days after priming, when hyperalgesia was resolved, rats were exposed to environmental stress and DNIC was evaluated by measuring hind paw response threshold to noxious pressure (test stimulus) after capsaicin injection in the forepaw (conditioning stimulus). Morphine priming without stress did not alter DNIC. However, stress produced a loss of DNIC in morphine-primed rats in both hind paws that was abolished by systemic administration of the KOR antagonist, nor-binaltorphimine (nor-BNI). Microinjection of nor-BNI into the right, but not left, central nucleus of the amygdala (CeA) prevented the loss of DNIC in morphine-primed rats. Diffuse noxious inhibitory controls were not modulated by bilateral nor-BNI in the rostral ventromedial medulla. Stress increased dynorphin content in both the left and right CeA of primed rats, reaching significance only in the right CeA; no change was observed in the rostral ventromedial medulla or hypothalamus. Although morphine priming alone is not sufficient to influence DNIC, it establishes a state of latent sensitization that amplifies the consequences of stress. After priming, stress-induced dynorphin/KOR signaling from the right CeA inhibits DNIC in both hind paws, likely reflecting enhanced descending facilitation that masks descending inhibition. Kappa opioid receptor antagonists may provide a new therapeutic strategy for stress-related functional pain disorders.

Neck/shoulder function in tension-type headache patients and the effect of strength training

Introduction

Muscle pain has been associated with reduced maximal muscle strength, and reduced rate of force development (RFD). Strength training (ST) has shown an effect in not only normalizing muscle function but also reducing neck muscle pain.

Aim

The aims of this study were to compare muscle function in terms of strength, force steadiness in neck flexion, as well as extension, and rate of RFD of the shoulder in tension-type headache (TTH) patients and healthy controls and to examine the correlation to tenderness. Furthermore, the aim of the study was to examine the effect of ST on neck and shoulder functions in TTH patients.

Participants and methods

In all, 60 TTH patients and 30 sex- and age-matched healthy controls were included for a case–control comparison. The 60 patients with TTH were randomized into an ST and an ergonomic and posture correction (EP) control group. The ST group trained for 10 weeks with elastic bands.

Results

TTH patients had a lower extension force steadiness with a significant 15% higher coefficient of variation (CoV) compared to healthy controls (p=0.047). A significantly lower RFD (25%) was noted in the TTH group than in the healthy controls (p=0.031). A significant (p<0.01) and moderate correlation to muscle tenderness was found. In the intervention, 23 patients completed ST and 21 patients completed EP. No significant between-group effect was observed, but at 22 weeks follow-up, both groups had a significant within-group effect of improved extension force steadiness (ST: p=0.011 and EP: p<0.01).

Conclusion

TTH patients showed a deteriorated muscle function, indicated by a lower force steadiness and RFD, compared to the healthy controls. The effect of ST was not larger than EP as both groups of TTH patients showed some improvement in neck and shoulder functions during the 10 weeks intervention and at follow-up. Future interventions are needed to elucidate if normalization of muscle function can lead to a reduction in headache.

Fructans Exacerbate Symptoms in a Subset of Children With Irritable Bowel Syndrome

BACKGROUND & AIMS

Dietary fructans exacerbate symptoms in some, but not all, adults with irritable bowel syndrome (IBS). We sought to determine whether fructans worsen symptoms in children with IBS and whether clinical and psychosocial factors, and/or gas production, can identify those who are fructan sensitive.

METHODS

We performed a double-blind placebo-controlled (maltodextrin) cross-over trial of 23 children with IBS, based on pediatric Rome III criteria, from September 2014 through December 2016. At baseline, participants completed 1-week pain and stool diaries and a 3-day food record and psychosocial factors (depression, anxiety, and somatization) were measured. Subjects were randomly assigned to groups that were provided meals for 72 hours containing either fructans or maltodextrin (0.5 g/kg; maximum, 19 g). Following a washout period of 10 days or more, the subjects received the meal they were not given during the first study period (crossed over). Gastrointestinal symptoms and breath hydrogen and methane production were captured during each meal period. Fructan sensitivity was defined as an increase of 30% or more in abdominal pain frequency following fructan ingestion.

RESULTS

Subjects had more mean episodes of abdominal pain/day during the fructan-containing diet (3.4 ± 2.6) vs the maltodextrin-containing diet (2.4 ± 1.7) (P < .01), along with more severe bloating (P < .05) and flatulence (P = .01). Hydrogen (but not methane) production was greater while subjects were on the fructan-containing diet (617 ± 305 ppm∗h) than the maltodextrin-containing diet (136 ± 78 ppm*h) (P < .001). Eighteen subjects (78.2%) had more frequent abdominal pain while on the fructan-containing diet and 12 (52.2%) qualified as fructan sensitive. We found no difference between fructan-sensitive and fructan-insensitive subjects in baseline abdominal pain or bowel movement characteristics, dietary intake, psychosocial parameters, IBS subtype, or gas production.

CONCLUSIONS

In a randomized controlled trial of children with IBS, we found fructans to exacerbate several symptoms. However, fructan sensitivity cannot be identified based on baseline gastrointestinal symptoms, dietary intake, psychosocial factors, or gas production. Clinicaltrials.gov no: NCT02842281.

Pain sensitivity and analgesic use among 10,486 adults: the Tromsø study

Background

Increased pain sensitivity is a putative risk factor for chronic pain and consequently for analgesic use. Conversely, analgesic use may be a cause of increased pain sensitivity, e.g., through opioid-induced hyperalgesia. We aimed to study the association between pain sensitivity and analgesic use in a general population, and to test the hypothesis that increased baseline pain sensitivity is a risk factor for future persistent analgesic use.

Methods

The Tromsø Study (2007–08), a population-based health study, was linked with eight years of prescription data from the Norwegian Prescription Database. The cold pressor test was completed in 10,486 participants aged 30+ years, and we used cold pressor endurance time as a proxy measure of pain sensitivity. Cross-sectional associations with different measures of analgesic use were assessed. Furthermore, a cohort of 9,657 persons was followed for 4.5 years.

Results

In the cross-sectional analysis, increased pain sensitivity was associated with analgesic use; regular users of opioids alone were more pain sensitive than regular users of non-opioid analgesics. Increased baseline pain sensitivity was a risk factor for persistent analgesic use, i.e., using non-steroidal anti-inflammatory drugs, paracetamol, or opioids for ≥ 90 days and proportion-of-days-covered ≥ 40% (HR = 1.22, 95% CI 1.06-1.40), although not statistical significant after confounder adjustment.

Conclusions

Increased pain sensitivity was associated with analgesic use in general, and reduced pain tolerance was found for both opioid and non-opioid analgesic users. The data suggest that hyperalgesia is an effect of analgesics, whereas pain tolerance has little impact on future analgesic use.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0149-2) contains supplementary material, which is available to authorized users.

Increased deep pain sensitivity in persistent musculoskeletal pain but not in other musculoskeletal pain states

Background

Pressure pain thresholds (PPTs) in a non-painful body area are known to be affected in some chronic pain states. The aim of this study is to investigate PPTs in a pain-free body part in relation to pain persistence and intensity in patients with musculoskeletal pain.

Methods

Patients with musculoskeletal pain were divided into three different pain groups: acute pain (pain duration < 3 months, n = 38), regularly recurrent pain (regularly recurrent pain duration > 3 months, n = 56), persistent pain (persistent pain duration >3 months, n = 52) and a healthy control group (n = 51). PPT measures were conducted over the tibialis anterior muscle on the right leg in all groups.

Results

The persistent pain group showed significantly lower PPTs over the tibialis anterior muscle compared to controls. No significant differences were found between the acute and regularly recurrent pain groups compared to healthy controls. Significant correlations, albeit small, were found between pain intensity and PPTs.

Conclusions

Increased deep pain sensitivity was found in patients with persistent musculoskeletal pain, but not in regularly recurrent pain or in acute pain. Yet, a limitation of the study is that it did not have sufficient power to detect small levels of increased deep pain sensitivity among the latter groups when compared to healthy controls.

Implications

Knowledge about increased general hypersensitivity in persistent musculoskeletal pain could be important in clinical treatment.

The Role of the Trigemino Cervical Complex in Chronic Whiplash Associated Headache: A Cross Sectional Study

OBJECTIVE

To investigate signs of central sensitization in a cohort of patients with chronic whiplash associated headache (CWAH).

BACKGROUND

Central sensitization is one of the mechanisms leading to chronicity of primary headache, and thus might contribute to CWAH. However, the pathophysiological mechanism of CWAH is poorly understood and whether it is simply an expression of the primary headache or has a distinct pathogenesis remains unclear. Thus, the factors involved in the genesis of CWAH require further investigation.

METHODS

Twenty-two patients with CWAH (20 females, 2 males; age 25-50 years, mean age 36.3 years) and 25 asymptomatic participants (13 females, 12 males; age 18-50 years, mean age 35.6 years) rated glare and light-induced discomfort in response to light from an ophthalmoscope. Hyperalgesia evoked by a pressure algometer was assessed bilaterally on the forehead, temples, occipital base, and the middle phalanx of the third finger. The number, latency, area under the curve, and recovery cycle of nociceptive blink reflexes elicited by a supraorbital electrical stimulus were also recorded.

RESULTS

Eight and 6 CWAH patients had migrainous and tension-type headache (TTH) profiles, respectively; the remainder had features attributable to both migraine and TTH. Patients in the whiplash group reported significantly greater light-induced pain than controls (8.48 ± .35 vs 6.66 ± .43 on a 0-10 scale; P = .001). The CWAH patients reported significantly lower pressure pain thresholds at all sites. For stimuli delivered at 20 second intervals, whiplash patients were more responsive than controls (4.8 ± .6 blinks vs 3.0 ± .6 blinks in a block of 10 stimuli; P = .036). While R2 latencies and the area under the curve for the 20 second interval trials were comparable in both groups, there was a significant reduction of the area under the curve from the first to the second of the 2-second interval trials only in controls (99 ± 8% of baseline in whiplash patients vs 68 ± 7% in controls; P = .009). The recovery cycle was comparable for both groups.

CONCLUSIONS

Our results corroborate previous findings of mechanical hypersensitivity and photophobia in CWAH patients. The neurophysiological data provide further evidence for hyperexcitability in central nociceptive pathways, and endorse the hypothesis that CWAH may be driven by central sensitization.

The Emotional Brain as a Predictor and Amplifier of Chronic Pain

Human neuroimaging studies and complementary animal experiments now identify the gross elements of the brain involved in the chronification of pain. We briefly review these advances in relation to somatic and orofacial persistent pain conditions. First, we emphasize the importance of reverse translational research for understanding chronic pain-that is, the power of deriving hypotheses directly from human brain imaging of clinical conditions that can be invasively and mechanistically studied in animal models. We then review recent findings demonstrating the importance of the emotional brain (i.e., the corticolimbic system) in the modulation of acute pain and in the prediction and amplification of chronic pain, contrasting this evidence with recent findings regarding the role of central sensitization in pain chronification, especially for orofacial pain. We next elaborate on the corticolimbic circuitry and underlying mechanisms that determine the transition to chronic pain. Given this knowledge, we advance a new mechanistic definition of chronic pain and discuss the clinical implications of this new definition as well as novel therapeutic potentials suggested by these advances.

Risk factors of chronic daily headache or chronic migraine

Chronic daily headache (CDH) is a common neurological condition that affects 1-4 % of the general population. Most individuals with CDH originally suffered from episodic headaches, but over time, this developed into CDH. Although the pathophysiology of CDH is not fully understood, recent clinical and epidemiological studies suggest some risk factors that are associated with an increased risk of transformation from episodic headaches. If risk factors can be identified, they could provide a base for aggressive preventive intervention and thus decrease the transformation from episodic headaches to eventual CDH. In this article, we review and summarize the current data on risk factors for CDH.

Update of chronic tension-type headache

Tension-type headache (TTH) is the most common type of primary headaches, and its chronic form, chronic tension-type headache (CTTH), is affecting 0.5 to 4.8 % of the worldwide population. Although the mechanism underlying CTTH remains unclear, the role of central versus peripheral mechanisms has always been discussed while explaining the pathogenesis of CTTH. There is always a debate on differential diagnosis between CTTH and chronic migraine without aura which are regarded as different aspects of chronic daily headache spectrum because of many similarities and fuzzy boundaries. Compared with pharmacological treatments, non-pharmacological treatments have been popular as alternative interventions for CTTH in recent years. This review summaries the update knowledge on CTTH and discusses the most interested questions regarding pathogenesis and therapeutic strategies of CTTH.

Muscles and their role in episodic tension-type headache: implications for treatment

BACKGROUND AND OBJECTIVE

Tension-type headache (TTH) imposes a heavy burden on the global population but remains incompletely understood and poorly managed.

DATABASES AND DATA TREATMENT

Here, we review current knowledge of peripheral factors involved in the mechanism of TTH and make recommendations for the treatment of episodic TTH based on these.

RESULTS

Peripheral activation or sensitization of myofascial nociceptors is most probably involved in the development of muscle pain and the acute episode of TTH. Repetitive episodes of muscle pain may sensitize the central nervous system resulting in progression of TTH to the chronic form. Thus, muscular factors may be responsible not only for the acute headache episode but also for chronification of the disorder. Simple analgesics and non-steroidal anti-inflammatory drugs are the mainstays of management of individual headache episodes. Ibuprofen 400 mg and aspirin 1000 mg are recommended as drugs of first choice based on treatment effect, safety profile and costs. Non-pharmacological therapies include electromyographic biofeedback, physiotherapy and muscle relaxation therapy. Future studies should aim to identify the triggers of peripheral nociception and how to avoid peripheral and central sensitization. There is a need for more effective, faster acting drugs for acute TTH.

CONCLUSION

Muscular factors play an important role in episodic TTH. Ibuprofen 400 mg and aspirin 1000 mg are recommended as drugs of first choice.

Pain frequency moderates the relationship between pain catastrophizing and pain

Background: Pain frequency has been shown to influence sensitization, psychological distress, and pain modulation. The present study examined if pain frequency moderates the relationship between pain catastrophizing and pain.

Method: A non-clinical (247 students) and a clinical (223 pain patients) sample completed the Danish versions of the Pain Catastrophizing Scale (PCS), Beck Depression Inventory, and the State Trait Anxiety Inventory and rated pain intensity, unpleasantness and frequency.

Results: In both samples, high pain frequency was found to moderate the association between pain catastrophizing and pain intensity, whereas low pain frequency did not. The psychometric properties and the factor structure of the Danish version of the PCS were confirmed.

Conclusions: This is the first study to validate the Danish version of the PCS and to show that pain frequency moderates the relationship between pain catastrophizing and reported pain in both non-clinical and clinical populations.

Sleep features and central sensitization symptoms in primary headache patients

BACKGROUND

Association between sleep disorders and headache is largely known. The aim of the present study was to evaluate sleep quality and quantity in a large cohort of primary headache patients, in order to correlate these scores with symptoms of central sensitization as allodynia, pericranial tenderness and comorbidity with diffuse muscle-skeletal pain.

METHODS

One thousand six hundreds and seventy primary headache out patients were submitted to the Medical Outcomes Study (MOS) within a clinical assessment, consisting of evaluation of frequency of headache, pericranial tenderness, allodynia and coexistence of fibromyalgia syndrome (FM).

RESULTS

Ten groups of primary headache patients were individuated, including patients with episodic and chronic migraine and tension type headache, mixed forms, cluster headache and other trigeminal autonomic cephalalgias. Duration but not sleep disturbances score was correlated with symptoms of central sensitization as allodynia and pericranial tenderness in primary headache patients. The association among allodynia, pericranial tenderness and short sleep characterized chronic migraine more than any other primary headache form. Patients presenting with FM comorbidity suffered from sleep disturbances in addition to reduction of sleep duration.

CONCLUSION

Self reported duration of sleep seems a useful index to be correlated with allodynia, pericranial tenderness and chronic headache as a therapeutic target to be assessed in forthcoming studies aiming to prevent central sensitization symptoms development.

Pressure pain thresholds fluctuate with, but do not usefully predict, the clinical course of painful temporomandibular disorder

Central sensitization elicits pain hypersensitivity and is thought to be causally implicated in painful temporomandibular disorder (TMD). This causal inference is based on cross-sectional evidence that people with TMD have greater sensitivity than controls to noxious stimuli. We tested this inference in the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) prospective cohort study of 3258 adults with no lifetime history of TMD when enrolled (visit 1). During 5 years of follow-up, 1 group labeled "persistent TMD cases" (n=72) developed first-onset TMD by visit 2 that persisted ⩾ 6 months until visit 3. Another group labeled "transient TMD cases" (n=75) developed first-onset TMD at visit 2, which resolved by visit 3. Randomly sampled "controls" (n=126) remained TMD-free throughout all 3 visits. At each visit, pressure pain thresholds (PPTs) were measured by algometry at 10 cranial and bodily sites. In persistent TMD case patients, mean PPTs reduced 43 kPa (P<.0001) between visits 1 and 2 and thereafter did not change significantly. In transient TMD case patients, mean PPTs reduced 41 kPa (P<.001) between visits 1 and 2, and then increased 20 kPa (P<.001) by visit 3. These patterns were similar after excluding cranial sites symptomatic for TMD. Importantly, visit 1 PPTs had no clinically useful prognostic value in predicting first-onset TMD (odds ratio [OR]=1.07, P=.15). Among first-onset case patients, visit 2 PPTs were modest predictors of persistent TMD (OR=1.36, P=.002). In this longitudinal study, PPTs reduced when TMD developed then rebounded when TMD resolved. However, premorbid PPTs poorly predicted TMD incidence, countering the hypothesis that PPTs signify mechanisms causing first-onset TMD.

Medication overuse headache

BACKGROUND

Medication overuse headache (MOH) affects between 1% and 2% of the general population but is present in up to 50% of patients seen in headache centers. There are currently no internationally accepted guidelines for treatment of MOH.

METHODS

A review of the current literature on MOH treatment and pathophysiology.

RESULTS

We conclude that headache frequency can be reduced to episodic headache in more than 50% of the patients by simple detoxification and information. Approximately half the patients will not have need for prophylactic medication after withdrawal. Pain perception is altered in patients with MOH but can be restored to a baseline pattern, indicating a reversible mechanism in the central sensitization leading to chronic pain. The great comorbidity with depression and anxiety could be a consequence of the altered serotonin metabolism indicating a reversible and potentially treatable condition.

CONCLUSION

Increased focus on MOH is extremely important, as MOH both can and should be treated and prevented. MOH is thus a diagnosis that should be considered in all chronic headache patients as the very first step in their management strategy. In the general population, prevention campaigns against MOH are essential to minimize chronic pain disability.

Indications for peripheral and central sensitization in patients with chronic scalp pain (trichodynia)

OBJECTIVES

The underlying mechanism of trichodynia (scalp/hair pain, is unknown). The aim of this study was to characterize chronic trichodynia and to conduct, for the first time, sensory testing in patients with trichodynia to learn about possible underlying mechanisms.

METHODS

Participants were 16 trichodynia patients and 19 healthy controls. Participants underwent testing of touch and pressure-pain threshold as well as allodynia in painful and pain-free scalp sites and in the hands (intact remote region). A trichogram (hair test) was conducted on painful and pain-free scalp sites to evaluate hair cycle abnormalities. The chronic pain was characterized as well.

RESULTS

Painful sites were characterized by decreased thresholds for light touch (P<0.01) and pressure pain (P<0.01) and high rates of static allodynia (94%) compared with adjacent pain-free sites and controls. A significant negative correlation was found between chronic pain intensity and scalp thresholds. Spontaneous and evoked pain existed only in scalp sites with hair cycle abnormalities. In addition, pressure-pain threshold in the hands was significantly lower in trichodynia patients compared with controls.

DISCUSSION

The cranial hyperalgesia and allodynia, the generalized hyperalgesia, and the correlation between hyperalgesia and chronic pain suggest that trichodynia is related with both peripheral and central sensitization, respectively. The coexistence of hair cycle abnormalities and chronic pain might suggest a common denominator for both phenomena, possibly mediated by proinflammatory agents. Clinical implications are discussed.

Factors associated with the pressure pain threshold in healthy Chinese men

OBJECTIVE

The goal of present study was to examine the influence of demographic characteristics, lifestyle, and metabolic factors on pressure-induced pain threshold.

DESIGN AND SETTING

The study population comprised 2,517 healthy men at second-phase recruitment of a population-based cohort in China. The pressure pain threshold (PPT) at two locations, triceps and inguinal lines, was obtained using a digital pressure algometer. Education and occupation, as well as lifestyle factors, were self-reported in a face-to-face interview. Blood lipid and fasting glucose were measured as a routine healthy check-up program.

RESULTS

A lower PPT was found among men with younger age, higher level of education, and non-manual occupation. In addition, men with central obesity and moderate leisure time physical exercise were more sensitive to muscle mechanical stimuli. PPT was significantly correlated with high-density lipoprotein cholesterol (β for triceps = 0.064, and β for inguinal lines = 0.052) in a multivariate linear regression model, after controlling for multiple variables. Elevated PPT was also found among subjects with hyperglycemia (both P for triceps and inguinal lines <0.001) and excess drinking (P for triceps = 0.005).

CONCLUSIONS

It is important for physicians and researchers to consider these variables when evaluating pain sensitivity in clinic and in research. The underling mechanisms between these factors and pressure pain perception are worthy of further exploration.

Pain sensitivity and pericranial tenderness in children with tension-type headache: a controlled study

Purpose

To compare tenderness and pain sensitivity in children (aged 7–17 years) with tension-type headache (TTH) and healthy controls using total tenderness score (TTS), pressure pain threshold (PPT), and pain perceived at suprapressure pain threshold (supraPPT).

Patients and methods

Twenty-three children with frequent episodic TTH, 36 with chronic TTH, and 57 healthy controls were included. TTS was measured bilaterally at seven pericranial myofascial structures. PPT and supraPPT were assessed in the finger, m. temporalis, and m. trapezius by a Somedic® algometer. SupraPPT was defined as the pain perceived at a stimulus calculated as the individual site-specific PPT + 50%.

Statistics

The effect of group, sex, age, headache frequency, intensity, and years on TTS, PPT, and supraPPT was analyzed by general linear models. Confirmatory factor analysis was analyzed for mutual relations between measurements.

Results and conclusion

Tenderness increased uniformly in both frequent episodic TTH (median 14; interquartile range [IQR] 10–18; P < 0.001) and chronic TTH (median 13; IQR 9–20; P < 0.001) compared to controls (median 5, IQR 3–11). However, the children with frequent episodic TTH and chronic TTH did not show significantly increased sensitivity when measured by PPT or supraPPT. Factor analysis confirmed that the site-specific measurements depended on general latent variables. Consequently, the PPT and supraPPT tests can be assumed to measure central pain-processing levels.

Central hypersensitivity in chronic hemiplegic shoulder pain

OBJECTIVE

This study aimed to examine the association of hemiplegic shoulder pain (HSP) with central hypersensitivity through pressure-pain thresholds (PPTs) in healthy, distant tissues.

DESIGN

This study is a cross-sectional study. A total of 40 patients (n = 20, HSP; n = 20, stroke without HSP) were enrolled in this study. PPTs were measured at the affected deltoid and the contralateral deltoid and the tibialis anterior using a handheld algometer. Differences in PPTs were analyzed by Wilcoxon's rank-sum test and with linear regression analysis, controlling for sex, a known confounder of PPTs.

RESULTS

The subjects with HSP had lower local PPTs than did the control subjects who have had a stroke when comparing the painful shoulders with the dominant shoulders of the controls and comparing the nonpainful shoulder and the tibialis anterior with the nondominant side of the controls. Similarly, those with HSP had lower PPTs compared with the controls in contralesional-to-contralesional comparisons as well as ipsilesional-to-ipsilesional comparisons.

CONCLUSIONS

The subjects with HSP have lower local and distal PPTs than the subjects without HSP. This study suggests that chronic shoulder pain may be associated with widespread central hypersensitivity, which has been previously found to be associated with other chronic pain syndromes. This further understanding can then help develop better treatment options for those with this HSP.

Altered pain perception in children with chronic tension-type headache: is this a sign of central sensitisation?

AIM

The aim of this article is to investigate if children (7-17 years) with frequent episodic tension-type headache (FETTH) or chronic TTH (CTTH) have an altered pain perception compared to healthy controls.

METHODS

We applied a pressure of five increasing intensities to m. trapezius and m. temporalis with a Somedic Algometer II. Visual analogue scale-score was rated and area under the curve (AUC) calculated. An average AUC in each person was used as an outcome variable in further univariate multiple linear regression analysis because factor analysis showed that AUC represents only one dimension underlying both muscles.

RESULTS

Participants included 22 children with FETTH, 36 children with CTTH and 57 controls. The CTTH group had a significantly higher AUC compared to the control group ( P < 0.001). The FETTH group represented an intermediate state. AUC did not change with increasing age, headache years, headache intensity, headache frequency or sex.

CONCLUSION

Children with CTTH show significantly increased pain sensitivity in a range of pressures compared to the FETTH group and the controls. Since AUC in m. trapezius and m. temporalis represents only one general latent tenderness, it might indicate that the altered pain perception is mainly due to central sensitisation.

Modulation of central sensitisation by detoxification in MOH: results of a 12-month detoxification study

BACKGROUND

Human and animal models suggest that central sensitisation plays a role in medication-overuse headache (MOH). We aimed to study pain perception in MOH patients before and a year after withdrawal.

METHODS

We examined pain perception in 35 MOH patients before and two, six and 12 months after detoxification. For baseline comparison, we tested 40 healthy controls. We measured cephalic and extra-cephalic pressure-pain thresholds and supra-threshold pressure-pain scores and extra-cephalic pain thresholds, supra-threshold pain scores and temporal summation for electrical stimulation.

RESULTS

Of the 35 patients, 21 patients completed the entire study and remained cured of MOH. Statistically significant differences between patients and healthy controls were found in cephalic pressure-pain thresholds (137.3 kPa vs. 170 kPa, P < 0.05), extra-cephalic pressure pain thresholds (213.3 vs. 274.3 kPa, P < 0.05), in cephalic supra-threshold pressure-pain scores measured on a 100 mm visual analogue scale (61 vs. 27 mm, P < 0.05) and extra-cephalic supra-threshold pain scores for electrical stimulation (19.0 vs. 10.0 mm, P < 0.05). Cephalic supra-threshold pain scores decreased statistically significantly from 50.3 mm at baseline to 28.0 mm at the 12-month follow-up. In contrast to controls, temporal summation was not found in MOH patients before withdrawal, but after detoxification temporal summation normalised.

CONCLUSION

The central nervous system is sensitised in patients with MOH. For the first time we demonstrate that the pain perception continues to normalise up to a year after detoxification. This emphasises the importance of detoxification and follow-up to prevent relapse.

Depression in headaches: chronification

PURPOSE OF REVIEW

Recent evidence supports the suggestion that migraine is a chronic disorder with episodic attacks that increase in frequency in a subgroup of patients, transforming migraine into a refractory chronic condition with poor outcome and severe impact. Among the risk factors for migraine chronification depression figures notably. Early diagnosis and management of risk factors in migraineurs prevent migraine chronification and its consequences. The scope of this article is to review depression as a potential cofactor for migraine chronification.

RECENT FINDINGS

Population-based studies revealed that migraineurs often have symptoms of depression, with strongest associations for migraine with aura. Patients with depression also have an increased risk for migraine, migraine with aura in particular. Twin studies showed similar findings. This bidirectional relationship suggests that migraine and depression may share common causative factors, possibly genetically determined, that might control migraine chronification. Migraine patients may develop depression as a result of the demoralizing experience of recurrent and disabling headaches and depressed patients may develop migraine because of increased pain sensitivity, in the basis of a common genetic background.

SUMMARY

We suggest that clinicians consider depression as part of migraine management in order to optimize treatment and avoid migraine progression.