Has aerobic exercise effect on pain perception in persons with migraine and coexisting tension-type headache and neck pain? A randomized, controlled, clinical trial

BACKGROUND

A large subset of persons with migraine suffers from coexisting tension-type headache and neck pain which may adversely affect the prognosis of migraine. Aerobic exercise has been shown to decrease migraine burden in these persons. Therefore, the aim of this study was to investigate whether the effect of aerobic exercise in persons with migraine and coexisting tension-type headache and neck pain can be explained by changes in pain perception.

METHOD

Seventy consecutively recruited persons with migraine and coexisting tension-type headache and neck pain were randomized into exercise group or control group. Aerobic exercise consisted of bike/cross-trainer/brisk walking for 45 min, three times/week for 3 months. Controls continued their usual daily activities. Pericranial tenderness, pain thresholds, supra-thresholds and temporal summation were assessed at baseline, after treatment and at follow-up (6 months from baseline).

RESULTS

Fifty-two persons with migraine and coexisting tension-type headache and neck pain completed the study. Aerobic exercise did not induce consistent changes in nociceptive pathways measured by pericranial tenderness, pressure pain thresholds and sensitivity to electrical stimulation.

CONCLUSION

The effect of aerobic exercise cannot be explained by measurable effects on the pain modulation system. Thus, the positive effect on migraine burden may rather be explained by positive alteration of avoidance behaviour. Aerobic exercise can be recommended as a safe and inexpensive migraine treatment strategy.

SIGNIFICANCE

This study adds further knowledge about the positive effect of aerobic exercise for persons with migraine and coexisting tension-type headache and neck pain. This effect cannot be measured by changes in pain modulation, but may rather be explained by positive alteration of avoidance behaviour.

Increased pain sensitivity in migraine and tension-type headache coexistent with low back pain: A cross-sectional population study

BACKGROUND

Low back pain is common in the general population and in individuals with primary headaches. We assessed the relative frequency of self-reported back pain in persons with and without primary headaches and examined pain sensitivity.

METHOD

A population of 796 individuals completed a headache interview based on ICHD criteria and provided data of interest in a self-administered questionnaire. Headache cases were classified into chronic (≥15) (CH) or episodic (<15 headache days/month) (EH). A total of 495 had a pericranial total tenderness score (TTS), and 494 had cephalic and extracephalic pressure pain thresholds (PPTs) assessed.

RESULTS

Adjusted for age, gender, education and poor self-rated health, 1-year relative frequency of back pain was higher in individuals with CH (82.5%) and EH (80.1%) compared to no headache group (65.7%). In persons with back pain, TTS was higher in CH, (26.3 ± 12.1) than in EH, (18.5 ± 10.0; p < 0.001) and higher in both groups than in those with no headache, 10.8 ± 8.5 (p < 0.001 and p < 0.001, respectively). In persons with back pain, temporalis PPT were lower in CH, 169.3 ± 57.8, than in EH, 225.2 ± 98.1, and in no headache group, 244.3 ± 105.4 (p = 0.02 and p = 0.01, respectively). In persons with back pain, finger PPT were lower in CH, 237.1 ± 106.7, than in EH, 291.3 ± 141.3, or in no headache group, 304.3 ± 137.4 (p = 0.02 and p < 0.001, respectively).

CONCLUSION

Back pain is highly frequent in individuals with CH, followed by EH and no headache. In persons with CH, back pain is associated with lower cephalic and extracephalic PPTs suggesting central sensitization may be a substrate or consequence of comorbidity.

SIGNIFICANCE

We found that back pain has high relative frequency in individuals with CH followed EH and no headache. Back pain is associated with low cephalic and extracephalic PPTs in individuals with CH. Central sensitization may be a substrate or consequence of this comorbidity of back pain and CH.

Neuroticism, depression and pain perception in migraine and tension-type headache

OBJECTIVES

People with migraine and tension-type headache (TTH) have psychiatric comorbidities. We aimed to test differences in mental health constructs by type and frequency of primary headache and associated pain sensitivity.

MATERIALS AND METHODS

Data on headache features, neuroticism (Eysenck Personality Questionnaire) and depression (Major Depression Inventory) were obtained from 547 individuals classified into chronic (≥15) or episodic (<15 headache days/month) and into pure migraine (n=43), pure tension type headache (TTH, n=97), migraine and TTH (n=83) and no headache diagnosis (controls, n=324) groups. A pericranial total tenderness score (TTS) and pressure pain thresholds (PPTs) were measured. Differences in mental health constructs were examined by headache frequency and type using generalized linear mixed models adjusting for sociodemographic covariates.

RESULTS

Depression scores were highest among people with chronic headache, lower in those with episodic headache, and lowest in controls. The chronic and episodic headache groups had higher neuroticism scores than controls. Mental health construct scores were highest for the migraine and TTH group and lowest in the control group. TTS and cephalic PPTs were correlated with neuroticism and depression and were higher in the chronic headache group compared to the no headache group even when adjusted for neuroticism and depression.

CONCLUSIONS

Neuroticism and depression scores are associated with headache frequency (chronic vs episodic) and are highest for migraine and TTH followed by pure TTH then migraine. Mental health constructs were correlated with but did not influence differences in TTS and PPTs between headache groups.

Possible Mechanisms of Pain Perception in Patients with Episodic Tension-Type Headache. A New Experimental Model of Myofascial Pain

A new experimental human model of myofascial pain using intramuscular infusion of a combination of bradykinin, serotonin (5-hydroxytryptamine), histamine, and prostaglandin E2 was applied to patients with episodic tension-type headache (ETTH) in order to examine pain perception. Fifteen patients with ETTH and 15 healthy controls completed the randomized, balanced, double-blinded, placebo-controlled study. Pain intensity, punctate hyperalgesia and allodynia, and pain quality were recorded. The combination induced a moderate and prolonged pain in both patients (median 51 min) ( P = 0.001) and controls (median 22 min) ( P = 0.001). Patients reported more pain than controls both after the combination ( P = 0.045) and after placebo ( P < 0.001). The McGill pain score [PRI(R)] was significantly higher in patients ( P = 0.002) and in controls ( P = 0.001), whereas pain quality and hyperalgesia were similar after the combination compared with placebo in the two groups. Due to side-effects nine subjects did not complete the study. The increased pain response, but similar qualitative pain perception, in ETTH patients may be explained by sensitization of peripheral nociceptors even though central mechanisms may also be involved.

Increased Prevalence of Tension-Type Headache Over a 12-Year Period is Related to Increased Pain Sensitivity. A Population Study

We recently reported an increase in prevalence and frequency of tension-type headache (TTH) over a 12-year period in the young Danish population. The aim of the present study was to analyse whether this increase was related to increased pain sensitivity. The study was a cross-sectional replicate of a large Danish population study. It compared 113 subjects aged 25-36 years in 2001, with 221 comparable subjects in 1989. Tenderness was considerably higher in 2001 than in 1989. When stratified according to presence of headache, the increase in tenderness was clinically and statistically significant only in women with frequent TTH. The pressure pain threshold was significantly lower in 2001 compared with 1989 in women with frequent TTH. The increase in tenderness in the population may predict an even higher prevalence of TTH in future. The changes support the hypothesis of central sensitization in TTH.

Experimental Induction of Muscle Tenderness and Headache in Tension-Type Headache Patients

The aim of the present study was to investigate the impact of static contraction of the shoulder and neck muscles on muscle tenderness and headache in patients with tension-type headache. Twenty patients with frequent episodic tension-type headache and 20 healthy age- and sex-matched controls were examined using a placebo-controlled cross-over design. The subjects performed static contraction of the trapezius muscles (active procedure) or the anterior tibial muscles (placebo procedure) with 10% of maximal force for 30 min. Total tenderness score, local tenderness score and headache intensity were evaluated before and after the static work. Changes in headache intensity were followed for 24 h. Pericranial tenderness increased significantly more in patients than in controls after the active procedure ( P = 0.04). The increase in pericranial tenderness tended to be higher after the active procedure than after the placebo procedure in patients ( P = 0.08) and in controls ( P = 0.07). Sixty per cent of the patients and 20% of the healthy controls developed headache after the active procedure. Fifty per cent of the patients and none of the controls developed headache after the placebo procedure. There was no significant difference in headache development between the active and the placebo procedure in patients or controls. These findings demonstrate that tension-type headache patients are more liable to develop shoulder and neck pain in response to static exercise than healthy controls.

Evaluation and Proposal for Optimization of Neurophysiological Tests In Migraine: Part 2—Neuroimaging and The Nitroglycerin Test

Neuroimaging methods have been widely used in headache and migraine research. They have provided invaluable information on brain perfusion, metabolism and structure during and outside of migraine attacks, contributing to an improved understanding of the pathophysiology of the disorder. Human models of migraine attacks are indispensable tools in pathophysiological and therapeutic research. This review of neuroimaging methods and the attack-provoking nitroglycerin test is part an initiative by a task force within the EUROHEAD project (EU Strep LSHM-CT-2004-5044837-Workpackage 9) with the objective of critically evaluating neurophysiological tests used in migraine. The first part, presented in a companion paper, is devoted to electrophysiological methods, this second part to neuroimaging methods such as functional magnetic resonance imaging, positron emission tomography and voxel-based morphometry, as well as the nitroglycerin test. For each of these methods, we summarize the results, analyse the methodological limitations and propose recommendations for improved methodology and standardization of research protocols.

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.

Treatment guidelines: implications for community-based headache treatment

Tension-type headache (TTH) is the most common form of headache in the community, affecting up to 80% of people from time to time. At least 10% of people experience episodic TTH on a frequent basis (up to 14 days per month) and the condition is chronic for 2- 3%.

Disability, anxiety and depression associated with medication-overuse headache can be considerably reduced by detoxification and prophylactic treatment. Results from a multicentre, multinational study (COMOESTAS project)

OBJECTIVE

The objective of this article is to investigate whether headache-related disability, depression and anxiety can be reduced by detoxification and prophylactic treatment in patients with medication-overuse headache (MOH).

METHODS

Patients with MOH were included from six centres in Europe and Latin America in a seven-month cohort study. Before and six months after treatment, the degree of disability was measured by the Migraine Disability Assessment (MIDAS) questionnaire, while anxiety and depression were measured by the Hospital Anxiety and Depression Scale (HADS).

RESULTS

A total of 694 patients with MOH were included, of whom 492 completed the study. Headache days were reduced by 58.4% from 23.6 to 9.8 days per month at six months ( P < 0.001). The MIDAS score was reduced by 57.1% from baseline 59.9 to 25.7 ( P < 0.001). Number of patients with depression was reduced by 50.7% from 195 to 96 and number of those with anxiety was reduced by 27.1% from 284 to 207 (both P < 0.001).

CONCLUSIONS

Disability, depression and anxiety were considerably reduced in patients with MOH by detoxification and prophylactic treatment. This emphasises the urgent need for increased awareness about avoiding overuse of headache medications and demonstrates that not only headache frequency but also disability are remarkably improved by adequate intervention.

Migrainous infarction: a Nordic multicenter study

BACKGROUND AND PURPOSE

Migrainous infarction (MI), i.e., an ischemic stroke developing during an attack of migraine with aura is rare and the knowledge of its clinical characteristics is limited. Previous case series using the International Classification of Headache Disorders (ICHD) included <10 cases which make conclusions less valid. This study aimed to describe characteristics and outcome of MI in a larger sample.

METHODS

We analyzed demographic data, risk factors, migraine medication, stroke localization, symptoms, and outcome in a sample of 33 patients with MI according to second edition of the ICHD criteria collected from seven Nordic headache clinics.

RESULTS

Amongst 33 patients with MI, there were 20 (61%) women and 13 (39%) men with the median age for stroke of 39 (range 19-76) years. Traditional risk factors for stroke were rare compared with Scandinavian young ischemic stroke populations. During the acute phase, 12 (36%) patients used ergotamines or triptans. Stroke was located in the posterior circulation in 27 (82%) patients and cerebellum was involved in 7 (21%). Except in two patients with brainstem infarctions, the outcome was favorable with total recovery or limited residual symptoms.

CONCLUSIONS

The prevalence of traditional risk factors was low and the infarctions were predominantly located in posterior circulation territory, supporting theories of migraine specific mechanisms. The outcome was in general favorable.

Guidelines for controlled trials of drugs in tension-type headache: second edition

The Clinical Trials Subcommittee of the International Headache Society published its first edition of the guidelines on controlled trials of drugs in tension-type headache in 1995. These aimed 'to improve the quality of controlled clinical trials in tension-type headache', because 'good quality controlled trials are the only way to convincingly demonstrate the efficacy of a drug, and form the basis for international agreement on drug therapy'. The Committee published similar guidelines for clinical trials in migraine and cluster headache. Since 1995 several studies on the treatment of episodic and chronic tension-type headache have been published, providing new information on trial methodology for this disorder. Furthermore, the classification of the headaches, including tension-type headache, has been revised. These developments support the need for also revising the guidelines for drug treatments in tension-type headache. These Guidelines are intended to assist in the design of well-controlled clinical trials in tension-type headache.

Abnormal brain processing of pain in migraine without aura: A high-density EEG brain mapping study

In the present study we used high-density EEG brain mapping to investigate spatio-temporal aspects of brain activity in response to experimentally induced muscle pain in 17 patients with migraine without aura and 15 healthy controls. Painful electrical stimuli were applied to the trapezius muscle and somatosensory-evoked potentials were recorded with 128-channel EEG with and without concurrent induced tonic neck/shoulder muscle pain. At baseline, the calculated P300 dipole for single stimuli was localized in the cingulate cortex. In patients, but not in controls, the dipole changed position from baseline to the tonic muscle pain condition (z = 29 mm vs. z = −13 mm, P < 0.001) and from baseline to the post-tonic muscle pain condition (z = 29 mm vs. z = −9 mm, P < 0.001). This may be the first evidence that the supraspinal processing of muscle pain is abnormal in patients with migraine without aura.

Memantine for Prophylaxis of Chronic Tension-Type Headache—A Double-Blind, Randomized, Crossover Clinical Trial

Treatment for chronic tension-type headache (CTTH) is unsatisfactory. Our aim was to investigate the efficacy of the N-methyl D-aspartate (NMDA) antagonist memantine in the prophylactic treatment of CTTH. We included 40 patients in a randomized, double-blind, placebo-controlled, crossover trial. Memantine 20–40 mg/day or placebo was each given for 10 weeks separated by a 2-week wash-out period; 29 patients completed the study. The primary efficacy variable, area-under-the-headache curve (duration X intensity), did not differ between memantine (1352 ± 927) and placebo (1449 ± 976; P = 0.10). Headache intensity in both sexes was significantly lower on a 0–10 verbal rating scale with memantine (3.8) than with placebo (4.1; P = 0.03). In women, area-under-the-headache curve was significantly lower with memantine (1343 ± 919) than with placebo (1555 ± 1019; P = 0.01). The most common side-effects were dizziness and nausea. In conclusion, although no statistically significant effect was seen in the primary end-point, some beneficial effects of memantine were observed in women. Memantine was shown to reduce pain intensity in CTTH patients, albeit to a limited extent. Future NMDA antagonists with higher efficacy could be of major interest as regards the pathophysiology and future treatment of CTTH and other chronic pain disorders.

The Usefulness and Applicability of a Basic Headache Diary Before First Consultation: Results of a Pilot Study Conducted In Two Centres

We tested the usefulness and applicability of a simplified headache diary in the diagnosis of migraine (M), tension-type headache (TTH) and medication overuse headache (MOH). The diary was given to headache patients before their first consultation at the headache centre. Seventy-six naive headache patients completed the study. Their understanding of the diary proved highly satisfactory. The patients' level of compliance was also good, with 71± returning the diary completely filled in. The data entered in the diary were deemed complete for the diagnostic purpose in 93± of cases. The level of agreement between headache information gathered through clinical interview and the headache diary was satisfactory. When comparing the diary with the clinical interview, sensitivity was 92± for M, 75± for TTH and MOH. Specificity was 58± for M and TTH, 87± for MOH. Combined use of a diagnostic diary and clinical interview is recommended from the first consultation for headache.

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

Altered pain sensitivity is believed to play an important role for chronification of headache. It has however mainly been evaluated in highly selected patients from headache clinics and never in longitudinal studies. The present study is a 12-year follow-up of a population-based study of primary headache disorders and pain perception, combining a diagnostic headache interview with examination of muscle tenderness and measurement of pressure pain thresholds in 1000 subjects drawn randomly from the general population in Denmark. The aim of the study was to explore the cause-effect relationship between the increased pain sensitivity and the development of headache. The pressure pain thresholds were normal at baseline but had decreased at follow-up in subjects who developed chronic tension-type headache over the 12-year period (p = 0.025). In subjects who developed frequent episodic tension-type headache the tenderness was normal at baseline but had increased at follow-up (p < 0.01) while the pain thresholds were normal both at baseline and at follow-up. The findings demonstrate that increased pain sensitivity is a consequence of frequent tension-type headache, not a risk factor, and support that central sensitization plays an important role for the chronification of tension-type headache.

Evaluation and proposal for optimalization of neurophysiological tests in migraine: part 1--electrophysiological tests

Neurophysiological testing has become a valuable tool for investigating brain excitability and nociceptive systems in headache disorders. Previous reviews have suggested that most neurophysiological tests have limited value for headache diagnosis, but a vast potential for exploring the pathophysiology of headaches, the central effects of certain pharmacological treatments and phenotype-genotype correlations. Many protocols, however, lack standardization. This meta-analytical review of neurophysiological methods in migraine was initiated by a task force within the EUROHEAD project (EU Strep LSHM-CT-2004-5044837-Workpackage 9). Most of the neurophysiological approaches that have been used in headache patients are reviewed, i.e. evoked potentials, nociception-specific blink reflex, single-fibre electromyography, neuroimaging methods (functional MRI, PET, and voxel-based morphometry) and the nitroglycerin attack-provoking test. For each of them, we summarize the results, analyse the methodological limitations and propose recommendations for improved methodology and standardization of research protocols. The first part is devoted to electrophysiological methods, the second to neuroimaging techniques and the NTG test.

Combination of low-dose mirtazapine and ibuprofen for prophylaxis of chronic tension-type headache

Chronic headaches are difficult to treat and represent the biggest challenge in headache centres. Mirtazapine has a prophylactic and ibuprofen an acute effect in tension-type headache. Combination therapy may increase efficacy and lower side effects. We aimed to evaluate the prophylactic effect of a combination of low-dose mirtazapine and ibuprofen in chronic tension-type headache. Ninety-three patients were included in the double-blind, placebo-controlled, parallel trial. Following a 4-week run-in period they were randomized to four groups for treatment with a combination of mirtazapine 4.5 mg and ibuprofen 400 mg, placebo, mirtazapine 4.5 mg or ibuprofen 400 mg daily for 8 weeks. Eighty-four patients completed the study. The primary efficacy parameter, change in area under the headache curve from run-in to the last 4 weeks of treatment, did not differ between combination therapy (190) and placebo (219), P = 0.85. Explanatory analyses revealed worsening of headache already in the third week of treatment with ibuprofen alone. In conclusion, the combination of low-dose mirtazapine and ibuprofen is not effective for the treatment of chronic tension-type headache. Moreover, the study suggests that daily intake of ibuprofen worsens headache already after few weeks in chronic tension-type headache.

A prospective, open-label, long-term study of the efficacy and tolerability of topiramate in the prophylaxis of chronic tension-type headache

This open study evaluates the effectiveness and safety of topiramate for the prophylaxis of chronic tension-type headache. Fifty-one patients were enrolled, of whom 46 completed 24 weeks of treatment with topiramate. Daily dosing was titrated from 25 mg to 100 mg by treatment week 4. The primary efficacy parameter was headache frequency at weeks 13-24 compared with baseline. Headache frequency declined from 23.50 +/- 5.32 days (baseline, mean, SD) to 12.58 +/- 6.28 days at weeks 13-24 (P < 0.0001), with frequency of severe headaches dropping from 8.18 to 3.14 days (P < 0.0001). The average headache intensity dropped from 6.13 to 2.07 on the visual analogue scale (P < 0.0001). These parameters were not significantly reduced at weeks 5-12. A 50% reduction in headache frequency was achieved in 73% of patients at weeks 13-24. Also improved were mood, sleep, quality of life (all parameters, P < 0.0001) as well as the Beck Depression Inventory-II (P < 0.0001). In addition, a highly significant weight loss of 2.14 kg (mean) was observed between baseline (71.64 +/- 10.65 kg) and week 24 [69.50 +/- 10.04 kg (SD)] (P < 0.0001). There were only few side-effects, none of these rated severe. The results provide preliminary confirmation of the efficacy and tolerability of topiramate in the prophylaxis of chronic tension-type headache.

Generalized hyperalgesia in patients with chronic tension-type headache

Increased pain sensitivity in the central nervous system may play an important role in the pathophysiology of chronic tension-type headache (CTTH). Previous studies using pain thresholds as a measure of central pain sensitivity have yielded inconsistent results and only a few studies have examined perception of muscle pain without involvement of adjacent tissues. It has been suggested that suprathreshold testing might be more sensitive than threshold measurements in evaluation of central hyperexcitability in CTTH. The aim of the study was to compare pain ratings to suprathreshold single and repetitive (2 Hz) electrical stimulation of muscle and skin in cephalic (temporal and trapezius) and extracephalic (anterior tibial) regions between patients with CTTH and healthy subjects. In addition, we aimed to examine gender differences in pain ratings to suprathreshold stimulation and degree of temporal summation of pain between patients and controls. Pain ratings to both single and repetitive suprathreshold stimulation were higher in patients than in controls in both skin and muscle in all examined cephalic and extracephalic regions (P < 0.04). Pain ratings to both single and repetitive suprathreshold electrical stimulation were significantly higher in female compared with male patients (P < 0.001) and in female compared with male controls (P < or = 0.001). The degree of temporal summation of muscular and cutaneous pain tended to be higher in patients than in controls but the differences were not statistically different. This study provides evidence for generalized increased pain sensitivity in CTTH and strongly suggests that pain processing in the central nervous system is abnormal in this disorder. Furthermore, it indicates that suprathreshold stimulation is more sensitive than recording of pain thresholds for evaluation of generalized pain perception.

Frequency of headache is related to sensitization: A population study

Central sensitization is thought to play an important role in the chronification of tension-type headache and in the maintenance and exacerbation of the migraine attack. It has, however, almost exclusively been studied in highly selected patients from headache clinics. The aim of the present study was to evaluate pain perception in primary headaches in the general population. Stimulus-response functions for pressure versus pain, tenderness and pressure pain thresholds were studied in a random sample of 523 adults from the general population. All results were controlled for the effects of age and gender. The area under the stimulus-response function was increased in chronic- and frequent episodic tension-type headache compared with subjects without headache (p<0.001, p<0.001) and in chronic tension-type headache compared with migraine (p=0.01). Increasing slope (p<0.0001) and displacement towards lower pressures was found in the following order: no headache, migraine, frequent episodic tension-type headache, chronic tension-type headache. The displacement of the stimulus-response function was closely associated with frequency of headache. Finally, the stimulus-response function tended to be qualitatively altered in patients with frequent headache. The findings demonstrate, for the first time in a population-based study, a close relation between altered pain perception and chronification of headache, which most likely can be explained by central sensitization.

Increased muscular and cutaneous pain sensitivity in cephalic region in patients with chronic tension-type headache

Increased excitability of the central nervous system generated by repetitive and sustained pericranial myofascial nociception may be responsible for transformation of episodic tension-type headache into chronic form. We aimed to compare mechanical and electrical (intramuscular and cutaneous) pain thresholds in trapezius and anterior tibial regions between 20 patients with chronic tension type headache and 20 healthy controls. Pain thresholds to three types of electrical stimulation (single pulse, 2 and 100 Hz) were significantly lower in patients than in controls in trapezius muscle (P < 0.02) and in skin overlying the trapezius muscle (P < 0.05), whilst electrical pain thresholds did not differ between groups in anterior tibial muscle and skin. Quantitative sensory testing revealed increased pain sensitivity in patients as assessed by pressure-controlled manual palpation (local tenderness score, LTS; P < 0.01) and by pressure algometry (mechanical pain thresholds; P < 0.05) in test areas over the trapezius muscle, but not the anterior tibial muscle. In summary, this study demonstrates lower pain thresholds in muscle and skin of the cephalic region but not in lower limb muscle and skin in patients with chronic tension-type headache than in healthy controls. Increased sensitivity in nociceptive pathways from cephalic region may be of importance in the pathophysiology of chronic tension type headache.

Glyceryl trinitrate may trigger endogenous nitric oxide production in patients with chronic tension-type headache

Experimental studies in humans have shown that nitric oxide (NO) may play an important role in initiation of primary headaches. It has been proposed that activation of L-arginine-NO pathway and increased endogenous production of NO may be responsible for NO induced headache. NO is synthesized from L-arginine and that reaction also yields citrulline. In the present study we aimed to investigate plasma levels of citrulline and arginine as markers of NO production after infusion of the NO donor, glyceryl trinitrate (GTN). We recruited 16 patients with chronic tension-type headache and 16 healthy controls. The subjects were randomly allocated to receive 0.5 microg/kg/min GTN or placebo over 20 min. Patients were examined on headache free days. Blood samples were collected at baseline and 60 min after start of infusion. Both patients and controls developed stronger immediate headache on the GTN day than on the placebo day (P = 0.008). The headache was more pronounced in patients than in controls (P = 0.02). Plasma levels of citrulline increased significantly 60 min after start of GTN infusion compared to placebo infusion in patients (P = 0.01) but not in controls (P = 0.50). Plasma levels of arginine were unchanged in both patients (P = 0.12) and controls (P = 0.18). We suggest that GTN administration may trigger endogenous production of NO in patients with chronic tension-type headache resulting in activation of perivascular sensory afferents.

Placebo response in clinical randomized trials of analgesics in migraine

The objective was to assess the placebo response in randomized clinical trials of analgesics in the treatment of migraine attacks. We included placebo-controlled studies that used the criteria of the International Headache Society for the diagnosis of migraine and headache response as the primary efficacy parameter. In the 11 studies that qualified for inclusion, headache response occurred after placebo treatment in 7-50% of the migraineurs with an average placebo response rate of 30% (95% confidence interval (CI) 23-36). Two hours after treatment with placebo an average of 9% (95% CI 7-12, range 7-17%) of the patients were found to be pain free. In conclusion, the average headache response rate to placebo was 30% in randomized clinical trials of analgesics in migraine with a tremendous variation among studies. Placebo response rates vary with the choice of primary efficacy measure as well as patient characteristics and study design.

Pain sensitivity in pericranial and extracranial regions

Chronic myofascial pain is very common in the general population. The pain is most frequently located in the shoulder and neck regions, and nociceptive input from these regions may play an important role for tension-type headache. The mechanisms leading to the frequent occurrence of muscle pain in the shoulder and neck regions are largely unknown. It is possible that the pain is caused by increased sensitivity of muscle nociceptors or by central sensitization induced by nociceptive input from muscle. The primary aim of the present study was to compare muscle pain sensitivity in the trapezius and anterior tibial muscles. The secondary aim was to investigate whether temporal summation, a clinical correlate of wind-up, is more pronounced in muscle than in skin and, if so, whether such a difference is more pronounced in the trapezius than in the anterior tibial region. Sixteen healthy subjects were included. Pressure-pain thresholds and electrical cutaneous and intramuscular pain thresholds were measured at standard anatomical points in the trapezius and anterior tibial regions. Temporal summation was assessed by repetitive electrical stimulation. Pressure-pain thresholds (P = 0.005) and intramuscular electrical pain thresholds (P = 0.006) were significantly lower in trapezius than in anterior tibial muscle. Temporal summation was present in skin and muscle of both regions (P < 0.001). The degree of temporal summation was significantly higher in muscle than in skin in the trapezius region (P = 0.02), but not in the anterior tibial region (P = 0.47). In conclusion, we found that muscle pain sensitivity was higher in the trapezius than in the anterior tibial muscle. We also demonstrated that temporal summation could be induced in both muscle and skin and, importantly, that temporal summation was significantly more pronounced in muscle than in skin in the trapezius but not in the anterior tibial region. These data may help to explain why chronic muscle pain most frequently is located in the shoulder and neck regions.

Induction of prolonged tenderness in patients with tension-type headache by means of a new experimental model of myofascial pain

Tenderness is the most prominent abnormal finding in patients with tension-type headache (TTH). Recently we developed a model of myofascial tenderness using intramuscular infusion of a combination of bradykinin, serotonin, histamine and prostaglandin E2. We aimed to examine tenderness after this combination in patients with episodic TTH (ETTH). Fifteen patients and 15 healthy controls completed the study. Participants received the combination into the non-dominant trapezius muscle in a randomized, double-blinded and placebo-controlled design. Local tenderness and stimulus-response functions, mechanical pain thresholds (PPDT) in the temporal region and on the finger, and total tenderness score (TTS) were recorded. A local, prolonged, and mild to moderate tenderness was reported both in patients (P = 0.001) and in controls (P = 0.001) after the combination compared with the placebo. The response to the combination tended to be increased in patients. The stimulus-response function was leftward shifted after the combination, compared with baseline in both groups. No changes in PPDT or TTS were found after the infusions, whereas baseline PPDTs were decreased in ETTH compared with controls (PPDTfinger: P = 0.033; PPDTtemporal: P = 0.015). Intramuscular infusion of a combination of endogenous substances induced prolonged tenderness in both patients with episodic TTH and healthy subjects. The present results suggest an increased excitability of peripheral muscle afferents in TTH.

Tender points are not sites of ongoing inflammation -in vivo evidence in patients with chronic tension-type headache

Increased muscle tenderness is the most prominent finding in patients with tension-type headache, and it has recently been shown that muscle blood flow is diminished in response to static exercise in tender points in these patients. Although tenderness has been ascribed to local inflammation and release of inflammatory mediators, the interstitial concentration of inflammatory mediators has not previously been studied in tender muscles of patients with tension-type headache. The aim of the present study was to investigate in vivo concentrations of prostaglandin E2 (PGE2), adenosine 5'-triphosphate (ATP), glutamate, bradykinin and other metabolites in a tender point of patients with chronic tension-type headache, in the resting state as well as in response to static exercise, and to compare findings with measurements in a matched non-tender point of healthy controls. We recruited 16 patients with chronic tension-type headache and 17 healthy control subjects. Two microdialysis catheters were inserted into the trapezius muscle and dialysates were collected at rest, 15 and 30 min after start of static exercise (10% of maximal force) and 15 and 30 min after end of exercise. All samples were coded and analysed blindly. There was no difference in resting concentration of any inflammatory mediators or metabolites between tender patients and non-tender controls (P > 0.05). We also found no difference in change in interstitial concentration of ATP, PGE2, glutamate, glucose, pyruvate and urea from baseline to exercise and post-exercise periods between patients and controls (P > 0.05). The present study provides in vivo evidence of normal interstitial levels of inflammatory mediators and metabolites in tender trapezius muscle in patients with chronic tension-type headache during both rest and static exercise. Thus, our data suggest that tender points in these patients are not sites of ongoing inflammation.

In vivo evidence of altered skeletal muscle blood flow in chronic tension-type headache

Painful impulses from tender pericranial muscles may play a major role in the pathophysiology of chronic tension-type headache. Firm evidence for peripheral muscle pathology as a cause of muscle pain and chronic headache is still lacking. Using a microdialysis technique, we aimed to estimate in vivo blood flow and interstitial lactate concentrations in the trapezius muscle at rest and during static exercise in patients with chronic tension-type headache and in healthy subjects. We recruited 16 patients with chronic tension-type headache and 17 healthy control subjects. Two microdialysis catheters were inserted into the trapezius muscle (on the non-dominant side) of subjects, and dialysates were collected at rest, 15 and 30 min after the start of static exercise (10% of maximal force) and 15 and 30 min after the exercise was completed. All samples were coded and analysed blind. The primary endpoints were to detect a difference between patients and controls in changes of muscle blood flow and the interstitial lactate concentration from baseline to exercise and post-exercise periods. The increase in muscle blood flow from baseline to exercise and post-exercise periods was significantly lower in patients than controls (P = 0.03). There was no difference in resting blood flow between patients and controls (P = 0.43). Resting interstitial concentration of lactate did not differ between patients (2.51 +/- 0.18 mM; mean +/- standard error of the mean) and controls (2.35 +/- 0.23 mM, P = 0.57). There was no difference in change in interstitial lactate from baseline to exercise and post-exercise periods between patients and controls (P = 0.38). The present study provides in vivo evidence of decreased blood flow in response to static exercise in a tender muscle in patients with chronic tension-type headache. We suggest that, because of increased excitability of neurones in the CNS, the central interpretation and response to normal sensory input are altered in patients with chronic tension-type headache. This may lead to enhanced sympathetically mediated vasoconstriction and thereby a decreased blood flow in response to static exercise.

Calcitonin gene-related peptide levels during nitric oxide-induced headache in patients with chronic tension-type headache

It has been proposed that nitric oxide (NO) induced headache in primary headaches may be associated with release of calcitonin gene-related peptide (CGRP). In the present study we aimed to investigate plasma levels of CGRP during headache induced by the NO donor glyceryl trinitrate (GTN) in 16 patients with chronic tension-type headache and 16 healthy controls. The subjects were randomly allocated to receive 0.5 microg/kg/min GTN or placebo over 20 min on two headache-free days. Blood samples were collected at baseline, 10, 20 and 60 min after start of infusion. Both patients and controls developed significantly stronger immediate headache on the GTN day than on the placebo day and the headache was significantly more pronounced in patients than in controls. There was no difference between the area under the CGRP curve (AUCCGRP) on GTN vs. placebo day in either patients (P=0.65) or controls (P=0.48). The AUCCGRP recorded on the GTN day did not differ between patients and controls (P=0.36). Both in patients and controls, CGRP levels changed significantly over time, on both the GTN and placebo days (P < 0.05). The present study indicates that NO-induced immediate headache is not associated with release of CGRP.

Possible mechanisms of glyceryl-trinitrate-induced immediate headache in patients with chronic tension-type headache

Nitric oxide (NO) plays an important role in the pathophysiology of primary headaches including chronic tension-type headache (CTTH). Thus, a NO synthase inhibitor reduces headache and muscle hardness while the NO donor glyceryl trinitrate (GTN) causes more headache in patients than in healthy controls. Sensitization of myofascial pain pathways is important in CTTH, and the aim of the present study was to investigate if such mechanisms may also explain GTN-induced immediate headache in patients with CTTH. In a randomized, double-blind, crossover study 16 patients with CTTH and 16 healthy subjects received intravenous infusion of GTN (0.5 microg/kg per min for 20 min) or placebo on two headache-free days separated by at least 1 week. Muscle hardness, myofascial tenderness, mechanical and heat pain thresholds were measured at baseline and at 60 min and 120 min after start of infusion. In patients, GTN infusion resulted in a biphasic response with immediate headache and more pronounced delayed headache. A similar but less pronounced response was seen in controls. There was no difference between GTN and placebo regarding muscle hardness, myofascial tenderness or pressure and heat pain thresholds in either patients or controls (P>0.05). The unchanged sensitivity of pericranial myofascial pain pathways indicates that peripheral and central sensitization is not involved in the mechanisms of GTN-induced immediate headache.