Pericranial tenderness is not related to nummular headache

The aim of the present study was to investigate whether nummular headache (NH) patients show increased pericranial tenderness in relation to healthy subjects, and to compare pericranial tenderness between both NH and chronic tension-type headache (CTTH) patients. Three tenderness (total, cephalic and neck) scores were objectively and blinded assessed in 10 NH patients, 10 CTTH subjects and 10 healthy matched controls. No significant differences were found in any tenderness score between the symptomatic and non-symptomatic sides in NH, or between right and left sides in either CTTH or control groups. All tenderness scores were significantly greater in CTTH patients compared with both NH patients and controls (P < 0.001), but not significantly different between NH patients and controls. Therefore, NH patients had lower tenderness than patients with CTTH and did not show increased tenderness when compared with healthy subjects. In addition, tenderness in NH patients was quite symmetrical between both the symptomatic and the non-symptomatic sides. The absence of increased pericranial tenderness could be clinically useful in distinguishing NH from CTTH. Current findings expand the evidence supporting the notion that NH is a non-generalized and rather limited disorder, marking the presence of a well-delimited painful zone.     

Predictors of response to botulinum toxin type A (BoNTA) in chronic daily headache

OBJECTIVE: To evaluate predictors of response to botulinum toxin type A (BoNTA; BOTOX, Allergan Inc., Irvine, CA, USA) in patients with chronic daily headache (CDH). BACKGROUND: Chronic migraine (CM) and chronic tension-type headache (CTTH) form the majority of CDH disorders. Controlled trials indicate that BoNTAis effective in reducing the frequency of headache and number of headache days in patients with CDH disorders. A recent migraine study found that patients with imploding or ocular types of headaches were responders to BoNTA, whereas those with exploding headaches were not. To date, there are no data on factors that might predict response to BoNTA in patients with CDH. METHODS: A total of 71 patients with CM and 11 patients with CTTH were treated with 100 units BoNTA. Every patient received at least 2 sets of injections at intervals of 12-15 weeks; fixed sites, fixed dose, and "follow-the-pain" approaches were used for the injections. A detailed medical history was taken for each patient in addition to recording Migraine Disability Assessment Scale (MIDAS) scores at baseline and every 3 months after each set of injections. Headache frequency was assessed throughout the study from baseline to weeks 24-27. Patients recorded the frequency, severity, and duration of headaches in Headache Diaries. Patients were divided into responders (> or = 50% reduction in both headache frequency and MIDAS scores compared with baseline) and nonresponders (< 50% reduction in either of the above variables). Variables analyzed for predictors of response include headache that is predominantly unilateral or bilateral in location, presence of cutaneous allodynia (scalp allodynia), and presence of pericranial muscle tenderness (also referred to as muscle allodynia). Chi-square analysis was used for parallel-group comparisons (proportion of CM responders vs proportion of CM nonresponders and proportion of CTTH responders vs proportion of CTTH nonresponders). RESULTS: In the CM group, 76.1% (54 /71) of patients were responders to BoNTA, of which 68.5% (37/54) had headache that was predominantly unilateral in location and the remaining 31.5% (17/54) had headache that was predominantly bilateral in location (both P < .01 vs CM nonresponders). Of the 23.9% (17/71) CM nonresponders, 76.5% (13/17) reported predominantly bilateral headache and in the remaining 23.5% (4/17) the headache was unilateral. In the CM responders group, 81.5% (44/54) had clinically detectable scalp allodynia, while pericranial muscle tenderness was present in 61.1% (33/54) (both P < .01 vs CM nonresponders). The presence of scalp allodynia and pericranial muscle tenderness in the CM nonresponders was 11.8% (2/17) and 17.6% (3/17), respectively. In the CTTH group where all patients (100%, 11/11) had bilateral headache, 36.4% (4/11) of patients were responders to BoNTA. All of those CTTH responders (100%, 4/4) had pericranial muscle tenderness (P < .05 vs CTTH nonresponders). None of the CTTH nonresponders had pericranial muscle tenderness. No clinically significant serious adverse events (AEs) were reported. Mild AEs, eg, injection-site pain that persisted for 1-9 days, were reported in 11 patients. One patient had transient brow ptosis. CONCLUSIONS: A greater percentage of patients with CM responded to BoNTA than patients with CTTH. Headaches that were predominantly unilateral in location, presence of scalp allodynia, and pericranial muscle tenderness appear to be predictors of response to BoNTA in CM, whereas in CTTH, pericranial muscle tenderness may be a predictor of response.     

Patients with chronic tension-type headache demonstrate increased mechano-sensitivity of the supra-orbital nerve

OBJECTIVE: This study aimed to establish whether increased sensitivity to mechanical stimuli is present in neural tissues in chronic tension-type headache (CTTH). BACKGROUND: Muscle hyperalgesia is a common finding in CTTH. No previous studies have investigated the sensitivity of peripheral nerves in patients with CTTH. DESIGN: A blinded controlled study. METHODS: Pressure pain thresholds (PPT) and pain intensity following palpation of the supra-orbital nerve (V1) were compared between 20 patients with CTTH and 20 healthy matched subjects. A pressure algometer and numerical pain rate scale were used to quantify PPT and pain to palpation. A headache diary was kept for 4 weeks to substantiate the diagnosis and record the pain history. RESULTS: The analysis of variance demonstrated significantly lower PPT for patients (0.86+/-0.13 kg/cm2) than controls (1.50+/-0.19 kg/cm2) (P<.001). Pain to palpation was also higher for patients (2.73+/-1.58) than controls (0.15+/-0.28) (P<.001).Within the CTTH group, intensity, frequency, and duration of the headaches were negatively correlated with PPT (rsor=0.72; P<.001). CONCLUSIONS: These findings reveal that mechanical hypersensitivity is not limited to muscles but also occurs in cranial nerves, and that the level of sensitization, either due to peripheral or central processes, is related to the severity of the primary headache.     

Referred pain from trapezius muscle trigger points shares similar characteristics with chronic tension type headache.

Referred pain and pain characteristics evoked from the upper trapezius muscle was investigated in 20 patients with chronic tension-type headache (CTTH) and 20 age- and gender-matched controls. A headache diary was kept for 4 weeks in order to confirm the diagnosis and record the pain history. Both upper trapezius muscles were examined for the presence of myofascial trigger points (TrPs) in a blinded fashion. The local and referred pain intensities, referred pain pattern, and pressure pain threshold (PPT) were recorded. The results show that referred pain was evoked in 85% and 50% on the dominant and non-dominant sides in CTTH patients, much higher than 55% and 25% in controls (P<0.01). Referred pain spread to the posterior-lateral aspect of the neck ipsi-lateral to the stimulated muscle in both patients and controls, with additional referral to the temple in most patients, but none in controls. Nearly half of the CTTH patients (45%) recognized the referred pain as their usual headache sensation, i.e. active TrPs. CTTH patients with active TrPs in the right upper trapezius muscle showed greater headache intensity and frequency, and longer headache duration than those with latent TrPs. CTTH patients with bilateral TrPs reported significantly decreased PPT than those with unilateral TrP (P<0.01). Our results showed that manual exploration of TrPs in the upper trapezius muscle elicited referred pain patterns in both CTTH patients and healthy subjects. In CTTH patients, the evoked referred pain and its sensory characteristics shared similar patterns as their habitual headache pain, consistent with active TrPs. Our results suggest that spatial summation of perceived pain and mechanical pain sensitivity exists in CTTH patients.     

Pericranial tenderness in chronic tension-type headache: the Akershus population-based study of chronic headache

Background

Most knowledge on chronic tension-type headache (CTTH) is based on data from selected clinic populations, while data from the general population is sparse. Since pericranial tenderness is found to be the most prominent finding in CTTH, we wanted to explore the relationship between CTTH and pericranial muscle tenderness in a population-based sample.

Methods

An age- and gender-stratified random sample of 30,000 persons aged 30-44 years from the general population received a mailed questionnaire. Those with a self-reported chronic headache were interviewed and examined by neurological residents. The questionnaire response rate was 71% and the interview participation rate was 74%. The International Classification of Headache Disorders II was used. Pericranial muscle tenderness was assessed by a total tenderness score (TTS) involving 8 pairs of muscles and tendon insertions. Cross-sectional data from the Danish general population using the same scoring system were used for comparison.

Results

The tenderness scores were significantly higher in women than men in all muscle groups. The TTS was significantly higher in those with co-occurrence of migraine compared with those without; 19.3 vs. 16.8, p = 0.02. Those with bilateral CTTH had a significantly higher TTS than those with unilateral CTTH. The TTS decreased significantly with age. People with CTTH had a significantly higher TTS compared to the general population.

Conclusions

People with CTTH have increased pericranial tenderness. Elevated tenderness scores are associated with co-occurrence of migraine, bilateral headache and low age.Whether the increased muscle tenderness is primary or secondary to the headache should be addressed by future studies.     

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.     

Myofascial trigger points and their relationship to headache clinical parameters in chronic tension-type headache

OBJECTIVE: To assess the presence of trigger points (TrPs) in several head and neck muscles in subjects with chronic tension-type headache (CTTH) and in healthy subjects; and to evaluate the relationship of these TrPs with forward head posture (FHP), headache intensity, duration, and frequency. BACKGROUND: Tension-type headache (TTH) is a headache in which myofascial TrPs in head and neck muscles might play an important etiologic role. DESIGN: A blinded, controlled, pilot study. METHODS: Twenty-five CTTH subjects and 25 matched controls without headache were studied. TrPs in bilateral upper trapezius, sternocleidomastoids, and temporalis muscles were identified according to Simons et al's diagnostic criteria: tenderness in a hyperirritable spot within a palpable taut band, local twitch response elicited by snapping palpation, and elicited referred pain with palpation. A TrP was considered active if the subject recognized the evoked referred pain as familiar headache. If the evoked referred pain was not recognized as familiar headache, the TrP was considered as latent. Side-view pictures of each subject were taken in both sitting and standing positions in order to assess FHP by measuring the cranio-vertebral angle. Both measurements were made by a blinded assessor. A headache diary was kept for 4 weeks in order to assess headache intensity, frequency, and duration. RESULTS: The mean number of TrPs on each CTTH subject was 3.9 (SD: 1.2), of which 1.9 (SD: 1.2) were active TrPs and 1.9 (SD: 0.8) were latent TrPs. Control subjects only exhibited latent TrPs (mean: 1.4; SD: 0.8). There was a significant difference between the CTTH group and the controls for active TrPs (P < .001), but not for latent TrPs (P > .05). Differences in the distribution of active and latent TrPs within each muscle were also significant for all the analyzed muscles (P < .01). CTTH subjects with active TrPs in the right upper trapezius muscle or left sternocleidomastoid muscle showed a greater headache intensity and duration, but not headache frequency, compared to those with latent TrPs (P < .05). Active TrPs in the right temporalis muscle were associated with longer headache duration (P < .01), whereas active TrPs in the left temporalis muscle were associated with greater headache intensity (P < .05). CTTH subjects with active TrPs in the analyzed muscles had a greater FHP than those with latent TrPs in both sitting and standing positions. Differences were only significant for TrPs in the left sternocleidomastoid and FHP in the sitting position (P < .01). CONCLUSIONS: Active TrPs in upper trapezius, sternocleidomastoid, and temporalis muscles were associated with CTTH. CTTH subjects with active TrPs usually reported a greater headache intensity and longer headache duration than those with latent TrPs. CTTH subjects with active TrPs tended to have a greater FHP than CTTH subjects with latent TrPs.     

Exteroceptive suppression periods and pericranial muscle tenderness in chronic tension-type headache: effects of psychopathology, chronicity and disability

We examined pericranial muscle tenderness and abnormalities in the second exteroceptive suppression period (ES2) of the temporalis muscle in chronic tension-type headache (CTTH; n = 245) utilizing a blind design and methods to standardize the elicitation and scoring of these variables. No ES2 variable differed significantly between CTTH sufferers and controls (all tests, P>0.05). We found no evidence that CTTH sufferers with daily or near daily headaches, a mood or an anxiety disorder, or high levels of disability exhibit abnormal ES2 responses (all tests, P>0.05). CTTH sufferers were significantly more likely than controls to exhibit pervasive tenderness in pericranial muscles examined with standardized (500 g force) manual palpation (P<0.005). Female CTTH sufferers exhibited higher levels of pericranial muscle tenderness than male CTTH sufferers at the same level of headache activity (P<0.0001). Elevated pericranial muscle tenderness was associated with a comorbid anxiety disorder. These findings provide further evidence of pericranial hyperalgesia in CTTH and suggest this phenomenon deserves further study. Basic research that better elucidates the biological significance of the ES2 response and the factors that influence ES2 assessments appears necessary before this measure can be of use in clinical research.     

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.     

Increased muscle pain sensitivity in patients with tension-type headache

Nociceptive mechanisms in tension-type headache are poorly understood. The aim was to investigate the pain sensitivity of pericranial muscles and a limb muscle in patients with tension-type headache. Experimental muscle pain was induced by standardized infusions of 0.5 ml of 1 M hypertonic saline into two craniofacial muscles (anterior temporalis (TPA) and masseter (MAS)) and a limb muscle (anterior tibial (TA)) in 24 frequent episodic tension-type headache patients (FETTH), 22 chronic tension-type headache patients (CTTH) and 26 age and gender matched healthy subjects. Headache patients were examined twice, both on days with and on days without headache. The pressure pain thresholds (PPTs) were determined before and after infusions. The subjects continuously reported intensity of saline-induced pain on an electronic visual analogue scale (VAS) and the perceived area of pain was drawn on anatomical maps. Headache patients demonstrated significantly lower PPTs, higher saline-evoked VAS pain scores and greater pain areas than healthy subjects at all the tested muscle sites (P<0.05). There was a significant gender difference for the PPTs in all three groups of participants (P<0.05) and for VAS pain scores in the CTTH patients (P<0.05). There was no difference in pain sensitivity between FETTH and CTTH or between patients with or without headache. In conclusion, the present study demonstrates the presence of generalized pain hypersensitivity both in FETTH and CTTH compared to controls which is unrelated to actual headache status and extends to include responses to longer-lasting stimuli which are clinically highly relevant. Gender differences in deep pain sensitivity seem to be a consistent finding both in healthy controls and patients with tension-type headache.     

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.     

Pericranial tenderness in tension headache

Forty patients with tension headache and 40 healthy comparable control persons were palpated by the same "blinded" observer. Tenderness in 10 pericranial muscles on each side was rated on a four-point scale. A Total Tenderness Score was calculated for each individual by adding the scores from all palpated areas. Headache patients had significantly higher scores than controls and also significantly higher tenderness in each point separately. Median normal values and confidence limits for tenderness are given. Among 23 patients with daily headache a correlation was found between headache intensity and Total Tenderness Score. It is likely that the pathologic tenderness in patients with tension headache is the source of nociception, but pain mechanisms are more complex, as evidenced by discrepancy between tenderness and pain in some patients. Pathologic tenderness should be a contributing criterion to the diagnosis of tension headache (muscle contraction headache).     

Pressure pain thresholds and thermal nociceptive thresholds in chronic tension-type headache

The nociceptive thresholds to mechanical and thermal stimuli in patients with chronic tension-type headache were compared. Palpation of pericranial tenderness was performed in 50 patients and a total tenderness score (TTS) was calculated. Palpation was repeated, and pressure pain thresholds (PPTs) were determined with a pressure algometer in the temporal and occipital regions. In 32 of the patients, pain thresholds for heat and cold and limens for detection of non-painful temperature changes were determined in the hands and the temporal regions. Twenty-four healthy volunteers served as controls. Scores obtained by manual palpation (TTS) at the first and second visit were positively correlated. A negative correlation between headache severity and PPT was found in the temporal region. A positive correlation between PPT in the temporal and occipital region was found, and PPT and TTS were negatively correlated. Thermal pain thresholds were consistently less extreme in patients compared to controls, and patients reporting severe headache on the examination day were those most sensitive to thermal pain. No difference was found between patients and controls with respect to detection of temperature changes. A correlation was found between PPT and the corresponding cold pain thresholds, but no correlation could be demonstrated between TTS and thermal pain thresholds. In conclusion, headache patients had decreased pain perception thresholds. Chronic tension-type headache might be a result of dysmodulation of nociceptive impulses, but it is likely that sensitized nociceptors also play a role.     

Bilateral pressure pain sensitivity mapping of the temporalis muscle in chronic tension-type headache

Purpose.— To analyze pressure pain sensitivity maps in chronic tension-type headache (CTTH) and healthy controls over nine locations covering the temporalis muscle.
Background.— Lower pressure pain thresholds (PPT) have been found in craniofacial muscles in patients with CTTH. Since the temporalis muscle can play a relevant role in the genesis or maintenance of headache, the determination of pressure pain sensitivity maps of this muscle is needed.
Methods.— A pressure algometer was used to measure PPT over 9 points of the temporalis muscle (3 points in the anterior part of the muscle, another 3 in the middle of the muscle, and the remaining 3 in the posterior part) in 15 females suffering from CTTH and 10 healthy women. A pressure pain sensitivity map of both dominant and nondominant sides in patients and controls was calculated.
Results.— Chronic tension-type headache patients showed lower PPT as compared with healthy subjects ( P  < .01). Further, PPT levels of the nondominant side were lower than those on the dominant side for controls ( P  < .01). Within the CTTH group, more bilaterally homogeneous pressure pain sensitivity maps with PPT decreased from the posterior to anterior column were found, whereas among controls, PPT distribution maps were inhomogeneous with side-to-side differences.
Conclusions.— Our data may provide preliminary new key information about muscle sensitivity, since it seems that pressure pain sensitivity maps could be different between CTTH patients and healthy subjects. Further studies with greater sample sizes and other headache populations are now required to confirm our results.     

Stretch reflex and pressure pain thresholds in chronic tension-type headache patients and healthy controls

To compare the jaw-stretch reflex and pressure pain thresholds (PPT) in chronic tension-type headache (CTTH) patients and healthy controls, 30 patients (15 male and 15 female) and 30 age- and sex-matched healthy subjects were investigated. Stretch reflexes were recorded in the temporalis and masseter muscles and PPT was determined in the anterior temporalis, splenius capitis and masseter muscles. The results showed that the amplitude of the stretch reflex in CTTH patients was higher compared with control subjects ( P  < 0.045), and higher in women compared with men in the right and left anterior temporalis muscles ( P  < 0.009). There were no differences in the PPT value between CTTH and control subjects ( P  > 0.509), whereas women showed significantly lower PPT measurements ( P  < 0.046). The results demonstrated a facilitation of the stretch reflex pathways in CTTH patients that is unrelated to measures of pericranial sensitivity.     

Neck mobility and forward head posture are not related to headache parameters in chronic tension-type headache

The relationship between the changes in forward head posture (FHP), neck mobility and headache parameters was analysed in 25 patients with chronic tension-type headache (CTTH) undergoing a physical therapy programme. Side-view pictures were taken to measure the cranio-vertebral angle in the sitting and standing positions. A cervical goniometer was employed to measure the range of all cervical motions. A headache diary was kept to assess headache intensity, frequency and duration. All patients received six sessions of physical therapy over 3 weeks. Outcomes were assessed at baseline, after treatment and 1 month later. Neck mobility and headache parameters showed a significant improvement after the intervention, whereas posture changes did not reach statistical significance. No correlations were found between FHP, neck mobility and headache parameters at any stage. Changes in these outcomes throughout the study were not correlated either. FHP and neck mobility appear not to be related to headache intensity, duration or frequency in patients suffering from CTTH. Although patients showed a reduction in the range of motion in the neck, it is uncertain whether this is consistent with TTH.     

Magnetic resonance imaging study of the morphometry of cervical extensor muscles in chronic tension-type headache

This study analyses the differences in the relative cross-sectional area (rCSA) of several cervical extensor muscles, assessed by magnetic resonance imaging (MRI), between patients with chronic tension-type headache (CTTH) and healthy controls. MRI of the cervical spine was performed on 15 CTTH females and 15 matched controls. The rCSA values for the rectus capitis posterior minor (RCPmin), rectus capitis posterior major (RCPmaj), semispinalis capitis and splenius capitis muscles were measured from axial T1-weighted images using axial MR slices aligned parallel to the C2/3 intervertebral disc. A headache diary was kept for 4 weeks in order to substantiate the diagnosis and record the pain history. CTTH patients showed reduced rCSA for both RCPmin and RCPmaj muscles (P < 0.01), but not for semispinalis and splenius capitis muscles, compared with controls. Headache intensity, duration or frequency and rCSA in both RCPmin and RCPmaj muscles were negatively correlated (P < 0.05): the greater the headache intensity, duration or frequency, the smaller the rCSA in the RCPmin and RCPmaj muscles. CTTH patients demonstrate muscle atrophy of the rectus capitis posterior muscles. Whether this selective muscle atrophy is a primary or secondary phenomenon remains unclear. In any case, muscle atrophy could possibly account for a reduction of proprioceptive output from these muscles, and thus contribute to the perpetuation of pain.     

Exteroceptive suppression of temporal muscle activity is normal in chronic tension-type headache and not related to actual headache state

The aim of the present study was to compare the late exteroceptive suppression period (ES₂) of temporalis muscle activity between patients with chronic tension-type headache and healthy controls, and to investigate the influence, if any, of actual headache on ES₂. ES₂ was recorded in 55 patients and in 55 controls with a previously evaluated methodology and analysed by a blinded observer. The first 20 patients were randomly studied on 2 additional days, 1 day with and 1 day without headache. The duration of ES₂ did not differ between patients and controls and did not differ on days with headache compared with days without headache. ES₂ duration was not related to the frequency of headache, headache intensity, age, pericranial muscle tenderness or electrical pain threshold. Our results strongly indicate that ES₂ is normal in chronic tension-type headache and therefore may not be related to the pathophysiology of this disorder.     

Myofascial trigger points and sensitization: an updated pain model for tension-type headache

Present pain models for tension-type headache suggest that nociceptive inputs from peripheral tender muscles can lead to central sensitization and chronic tension-type headache (CTTH) conditions. Such models support that possible peripheral mechanisms leading to pericranial tenderness include activation or sensitization of nociceptive nerve endings by liberation of chemical mediators (bradikinin, serotonin, substance P). However, a study has found that non-specific tender points in CTTH subjects were not responsible for liberation of algogenic substances in the periphery. Assuming that liberation of algogenic substances is important, the question arising is: if tender muscle points are not the primary sites of on-going neurogenic inflammation, which structure can be responsible for liberation of chemical mediators in the periphery? A recent study has found higher levels of algogenic substances, and lower pH levels, in active myofascial trigger point (TrPs) compared with control tender points. Clinical studies have demonstrated that referred pain elicited by head and neck muscles contribute to head pain patterns in CTTH. Based on available data, an updated pain model for CTTH is proposed in which headache can at least partly be explained by referred pain from TrPs in the posterior cervical, head and shoulder muscles. In this updated pain model, TrPs would be the primary hyperalgesic zones responsible for the development of central sensitization in CTTH.     

Heat pain thresholds and cerebral event-related potentials following painful CO2 laser stimulation in chronic tension-type headache

Current opinion concerning the pathophysiology of tension-type headache (TTH) and its related pericranial muscle tenderness proposes a primary role of central sensitization at the level of dorsalhorn/trigeminal nucleus as well as the supraspinal level. Investigation of these phenomena can be conducted using laser-evoked potentials (LEPs), which are objective and quantitative neurophysiological tools for the assessment of pain perception. In the present study we examined features of LEPs, as well as cutaneous heat-pain thresholds to laser stimulation, in relation to the tenderness of pericranial muscles in chronic TTH resulting from pericranial muscle disorder, during a pain-free phase. Twelve patients with TTH and 11 healthy controls were examined using the Total Tenderness Scoring (TTS) system. The stimulus was a laser pulse generated by a CO(2) laser. The dorsum of the hand and the cutaneous zones corresponding to pericranial muscles were stimulated. Subjective perception of stimulus intensity was assessed by a visual analogue scale. Two responses, the earlier named N2a and the last named P2, were considered; the absolute latency was measured at the highest peak of each response. The N2a-P2 components' peak-to-peak amplitude was detected. The heat pain threshold was similar in TTH patients and controls at the level of both the hand and pericranial skin. The TTS scores at almost all pericranial sites were higher in TTH patients than in normal controls. The amplitude of the N2a-P2 complex elicited by stimulation of the pericranial zone was greater in TTH patients than in controls; the amplitude increase was significantly associated with the TTS score. Our findings suggest that pericranial tenderness may be a primary phenomenon that precedes headache, and is mediated by a greater pain-specific hypervigilance at the cortical level.