Site Specificity of Pain and Tension in Tension-Type Headaches

Previous studies have not found a significant correlation between location of pain and electromyogram levels in chronic headache patients. However, these studies only examined a limited number of muscle groups and did not assess subjective tension levels. The present study evaluated a group of tension-type (n = 43) and migraine and tension-type (n = 30) headache patients. Measures were obtained at five muscle sites (frontalis, temporalis, masseter, splenius capitis, and trapezius) for patient ratings of headache pain, patient ratings of muscle tension, and electromyogram recordings cross-sectionally. Neither subjective pain nor tension ratings were found to be significantly related to electromyogram levels. The site-specificity relationship between chronic headache pain, subjective report of muscular tension, and electromyogram levels remains unclear.     

Absolute and Proportional Resting EMG Levels in Muscle Contraction and Migraine Headache Patients

SYNOPSIS
In this study, resting EMG levels were measured in the frontalis and temporalis muscle in patients suffering from muscle contraction headache, migraine, or mixed muscle contraction-migraine headache. The EMG levels of these groups were never significantly higher than those of a control group of subjects without headaches. Significantly higher levels, however, were found in both muscles in the migraine and mixed headache groups if the resting EMG levels were expressed as a percentage of the EMG level during maximal contraction. There was a tendency for proportional EMG levels of both muscles in the muscle contraction headache group to be significantly elevated. Headache patients generally showed lower maximal EMG levels than control subjects. The significance of this finding is discussed in relation to the etiology of the headaches. It is concluded that proportional EMG levels are a better index of the state of contraction than absolute EMG levels and are preferable in investigations of headache.     

Stress-induced pain and muscle activity in patients with migraine and tension-type headache

We recorded deep pain and surface electromyographic (EMG) responses to stress in 22 migraineurs during headache-free periods, 18 patients with tension-type headache (TTH), and 44 healthy controls. Sixty minutes of cognitive stress was followed by 30 min relaxation. EMG and pain (visual analogue scale) in the trapezius, neck (splenius), temporalis and frontalis areas were recorded. TTH patients had higher pain responses in temporalis and frontalis (with similar trends for trapezius and splenius) and more potentiation of pain during the test than controls. Migraine patients developed more pain in the splenius and temporalis than controls. Muscle pain responses were more regional (more pain in the neck and trapezius compared with the temporalis and frontalis) in migraine than in TTH patients. TTH patients had delayed pain recovery in all muscle regions compared with controls, while migraine patients had delayed pain recovery in a more restricted area (trapezius and temporalis). EMG responses were not different from controls in headache patients, and EMG responses did not correlate with pain responses. TTH patients had delayed EMG recovery in the trapezius compared with controls and migraine patients. These results support the concept that (probably central) sensitization of pain pathways and the motor system is important in TTH. Less pronounced and more regional (either peripheral or central) trigeminocervical sensitization seems to be important in migraine. Surface-detectable muscular activation does not seem to be causal for pain during cognitive stress either in migraine or in TTH.     

A Psychophysiological Investigation of Tension Headache

SYNOPSIS
In a psychophysiological investigation of tension headache cases (n = 23) with migraine headache controls (n = 10) and non-headache controls (n = 30), both tonic and phasic activity of the key muscles (frontalis and temporalis) and the temporal artery pulse were examined. Although all headache cases had significantly elevated levels of temporalis tension, tension headache sufferers were not differentiated from migraine in this respect. A substantial subgroup of tension sufferers (30%) had no detectable muscular or arterial abnormality associated with their severe pain. Idiosyncratic stress stimuli evoked significant frontalis reactivity in all headache cases (tension and migraine). These responses were triggered only by potent stimuli. Migraine cases had higher level of temporal artery abnormality at rest, in response to stress, and during pain episodes than tension cases. The implications of these results were discussed with respect to the prevailing view of tension headaches. An alternative model of this disorder was considered.     

Absolute and Proportional Resting EMG Levels in Chronic Headache Patients in Relation to the State of Headache

SYNOPSIS
In the present study, resting EMG levels were measured bilaterally in the frontalis and temporalis muscles in muscle contraction headache, migraine, and mixed muscle contraction-migraine headache patients and in healthy control subjects. Besides absolute EMG levels, proportional EMG levels were obtained by relating the absolute EMG amplitude to the EMG amplitude during maximal contraction. The headache-free state, a state of relatively weak headache, and a state of relatively strong headache were examined. The data of the three patient groups were pooled because significant differences between the groups were absent. Absolute EMG levels in the patients during the headache-free state were not significantly different from those of the controls except for the right frontalis muscle where the patients showed significantly higher levels than the controls. Proportional EMG levels, however, were for all muscles significantly higher in the patients group. Maximal EMG levels were generally significantly lower in the patients than in the controls. In the patients group, both absolute, proportional, and maximal EMG levels were in most cases not significantly different between a state of relatively weak and a state of relatively strong headache. The significance of these findings with respect to the generation of head pain is discussed.     

EMG in common migraine: Changes in absolute and proportional EMG levels during real-life stress

The absolute and proportional EMG levels of the frontal, temporal, and corrugator muscles of 37 migraine patients and 37 matched controls were recorded during three experimental sessions: adaptation and real-life and experimental stress, both of long duration. Migraine patients did not show significantly different absolute EMG levels but had higher proportional EMG levels of the corrugator muscle than controls in each session. Migraine patients did not have different facial muscle responses to stress, and the two experimental groups reacted similarly to real-life and experimental stress. No relation was found between muscle activity and reported headache within 24 h after real-life stress. Increased EMG activity due to stress does not seem to be a significant cause of headache in common migraine as defined in this study, but rather a response to pain. Migraine patients with headache during stress showed lower muscle tension than patients without headache.     

Migraine and Tension Headache: Is There a Physiological Difference?

SYNOPSIS
The purpose of this study was to conduct a controlled comparison of tension and migraine headache under several experimental conditions.
Ten subjects from each of the following diagnostic groups - tension headache, migraine headache, and healthy controls - were observed under conditions of unstructured relaxation, mild stress, and recovery from stress. Forearm and forehead muscle potential, peripheral temperature, electrodermal response, heart rate, and systolic and diastolic blood pressure were monitored during these sessions. In addition, ratings of pain were obtained, and booklets II and III of the Edwards Personality Inventory were completed by each subject. The hypotheses that tension headache is associated with increased frontalis muscle tension and that migraine headache is associated with increased vasomotor activity were not supported with respect to resting levels, response to physical or psychological stress, or in relationship to pain. Personality differences between the three groups were observed. Migraine subjects appeared to be more perfectionistic and success-oriented than the other groups: and tension headache subjects, more anxious and insecure. It was suggested that although personality differences indicate the existence of two distinct disorders, physiological variables that were believed to be basic to the pathophysiology of these headaches (e.g. frontalis EMG in tension headache) do not distinguish these two types of headache.     

FRONTALIS EMG RESPONSE TO STRESS IN SUBJECTS WITH FREQUENT MUSCLE-CONTRACTION HEADACHES

SYNOPSIS
Frontalis electromyogram (EMG) activity was monitored in ten subjects with a high frequency of muscle contraction headaches, and ten subjects with low frequency of muscle contraction headaches at rest, during stressful mental artithmetic and after stress. The frontalis EMG activity of the high-frequency headache group was significantly greater than that of the low-frequency headache group in the pre-stress condition. Significant increases in EMG activity from pre-stress to stress were found in the low-frequency headache group but not the high-frequency headache group. Significant correlations were found between perceived level of relaxation and EMG in the low-frequency headache group, but not for the high frequency headache group.     

Head Pain as a Result of Experimental Ischemic Exercise of the Temporalis Muscle

SYNOPSIS
Reports indicate that ischemia relative to cranial muscle activity accompanies muscle contraction headache and jaw claudication. The purpose of this study was to experimentally create ischemia in exercising temporalis muscle in order to determine if this combination would produce head pain. Ten subjects were studied during each of three experimental conditions: temporalis muscle ischemia, rhythmic temporalis muscle exercise, and both ischemia and temporalis muscle exercise combined. Ischemia was produced by a scalp sphygmomanometer and verified by Doppler ultrasonic flowmetry of the superficial temporal artery. Temporalis muscle exercise was produced by gum chewing at 60 strokes/min using 30% of maximum electromyographic (EMG) activity. The time to onset of pain and the time to reach pain tolerance were measured. Pain, using either exercise or ischemia alone developed in a median time of 27 minutes and was seldom located in the temporal area. Pain, using both exercise and ischemia, developed in a median time of three minutes and was predominantly located in the temporal area. Both onset and tolerance times were shorter in the combined protocol when compared to ischemia or exercise alone (r<.001). Tenderness to palpation was observed in the temporal muscle following the combined procedure but not following the individual procedures. The results support the view that ischemic temporal muscle activity can produce head 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.     

Multiple clinical and paraclinical analyses of chronic tension-type headache associated or unassociated with disorder of pericranial muscles

Thirty-two female patients fulfilling the diagnostic criteria of chronic tension-type headache underwent multiple clinical (severity index before and after biofeedback therapy; anxiety score) and paraclinical (pericranial EMG levels and pressure-pain thresholds, temporalis exteroceptive silent period) assessments. Twenty-three patients (72%) had at least one increased EMG level and/or at least one decreased pain threshold and qualified for the subgroup" associated with disorder of pericranial muscles" (code 2.2.1). Nine patients (28%) were within the normal range for both investigations and would have been classified in the subgroup "unassociated with such disorder" (code 2.2.2). No significant differences were found between these two groups of patients for headache severity, anxiety, response to biofeedback therapy or duration of temporalis second exteroceptive silent period. The various clinical and paraclinical parameters were not significantly correlated to each other. It is therefore suggested that the subdivision of chronic tension-type headache in two subgroups based on pericranial EMG levels and/or pain sensitivity might be artificial. Since both of the latter and temporalis silent periods vary independently, they appear complementary in the study of tension-type headache patients and probably represent peripheral abnormalities, which are induced to varying intensities by a common central nervous system dysfunction.     

Stress, Temporal Artery Activity, and Pain in Migraine Headache: a Prospective Analysis

SYNOPSIS
Temporal artery, frontal EMG, systemic blood pressure, peripheral temperature, heart rate, and anxiety levels were monitored daily four days preceding a typical migraine attack and during the headache in twelve female migraine cases. The specific relationship between temporal artery activity and anxiety and temporal artery activity and pain was also determined. The results indicated the presence of an increased variability in the right temporal artery three days preceding the migraine with the absence of changes in the general autonomic and skeletal muscle measures. Considerable individual differences in temporal artery amplitude were observed necessitating an analysis of individual patients which revealed a general pattern of dilation three days prior to the attack and constriction the day preceding the attack. Increased anxiety was noted only on the headache day. Elevations in anxiety four days prior to the migraine were associated with the increased temporal artery variability observed three days prior to the attack. Anxiety experienced on the headache day was not related to changes in temporal artery amplitude variability or pain. Temporal artery dilation was not consistently associated with the site of pain. The results provide support for a disregulation theory of migraine relating anxiety to temporal artery change across days preceding the attack but question major assumptions regarding anxiety, temporal artery activity and pain during the headache itself.     

EMG Activity in Pericranial Muscles During Postural Variation and Mental Activity in Healthy Volunteers and Patients With Chronic Tension Type Headache

EMG activity was recorded over frontalis, temporalis and trapezius muscles in a supine position, a standing position and during a mental task in 32 female patients suffering from chronic tension-type headache and in 20 healthy volunteers. Measurements in patients were made before and after biofeedback therapy. All EMG levels were on average significantly higher in patients than in controls. 62.5% of patients had at least one abnormal EMG level, but only 34% were beyond the normal range, if 1 muscle and 1 recording condition was considered. EMG levels were not correlated with headache severity, anxiety or response to biofeedback treatment. It is therefore suggested that pericranial EMG activity is not pathogenetic in chronic tension type headache, but merely one of several pathophysiologic changes, that are produced by a central dysfunction.     

Activity of masticatory muscles in subjects with different orofacial pain conditions

The existence of a pathophysiological link between tonic muscle activity and chronic muscle pain is still being debated. The purpose of this retrospective, controlled study was to evaluate the electromyographic (EMG) activity of masticatory muscles in subjects with different orofacial pain conditions. The temporal and masseter EMG activity at rest and the masseteric reflex were recorded in two groups of patients with either myofascial pain (n=33) or neuropathic pain (n=20), one group of non-pain patients with disc derangement disorders (n=27) and one control group of healthy, asymptomatic subjects (n=32). The EMG activities of both muscles at rest were significantly higher in the pain patient groups compared to the asymptomatic control group. There was no significant difference between the disc derangement disorder group and the control group. The masseteric reflex amplitude was reduced in all patient groups when compared with the control group. In pain patient groups, the increased EMG activity at rest and the reduction of the masseteric reflex amplitude were equally distributed in the pain and non-pain sides. In addition, subjects presenting with bilateral pain showed higher EMG activity at rest than those with unilateral pain. These results suggested that the modulation of muscle activity was not the direct consequence of a peripheral nociceptive mechanism and seemed to indicate that a central mechanism was at work. The contrast between the increased EMG activity at rest and the reduction of the masseteric reflex amplitude may reflect modulations of motoneurones that differed in tonic versus phasic conditions in chronic pain patients.     

Muscular disorders in tension-type headache

In order to evaluate the diagnostic criteria for muscular disorders in tension-type headache, pericranial muscle tenderness and pressure pain thresholds were studied in a random sample population of 735 adults aged 25–64. In addition, quantitative EMGs were recorded in 547 of these subjects. The correlation between the three diagnostic tests was assessed and the discriminality and cut-off points were analysed using Receiver Operating Characteristics analysis. Local tenderness from the temporal muscles was closely related to the total tenderness scores from 14 pairs of muscles. In chronic tension-type headache, tenderness was positively related to EMG and inversely related to pain thresholds. In the episodic form the total tenderness score was inversely related to pain thresholds, whereas no significant relation to EMG was noted. The Receiver Operating Characteristics curves indicated that tenderness recorded by manual palpation was the most specific and sensitive test, whereas EMG and pain thresholds were of limited diagnostic value. Eighty-seven percent of subjects with the chronic, and 66% of subjects with the episodic form were found to have a "muscular disorder" defined as increased tenderness recorded by either manual palpation or pressure algometry and/or increased EMG levels. However, muscle tenderness increased significantly during pain, so the headache state should be considered in future studies. Suggestions for revision of the present diagnostic criteria for muscular disorders are given.     

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.     

The Effects of Psychological Stress on Electromyographic Activity and Negative Affect in Ambulatory Tension-Type Headache Patients

Fourteen female dental hygiene students (seven with episodic tension-type headache and seven who rarely or never experienced headache) wore an ambulatory electromyographic recorder and completed hourly subjective ratings of pain and negative affective states for six days while they carried out their normal daily activities. Three of the days were designated as high stress days by virtue of the fact that the students were required to take a major course examination or undergo a clinical evaluation on that day. The remaining three days were designated as low stress days by virtue of the fact that no unusual demands were made on the students, and they simply attended lectures as usual. All students showed significantly greater levels of electromyographic activity on the high stress days compared to the low stress days, but there was not a statistically significant difference between the headache and control groups. Headache group subjects reported significantly higher levels of pain compared to the control group, but their pain ratings did not differ between high and low stress days. Subjective ratings of negative affective states (anxiety, anger, sadness, and frustration) were significantly greater on high stress days compared to low stress days. Headache group subjects also exhibited a tendency to report higher levels of negative affective states than did control group subjects, but only in the case of frustration was the .05 level of statistical significance achieved.     

The use of electromyography and muscle palpation in the diagnosis of tension-type headache with and without pericranial muscle involvement.

The Headache Classification Committee of the International Headache Society recently issued revised diagnostic criteria for headache disorders. According to these criteria, tension-type headache may be subclassified depending upon whether pericranial muscle disorder is found. The presence or absence of pericranial muscle disorder was to be determined by palpating the muscles for tenderness or by measuring electromyographic (EMG) activity. In this study, pericranial muscles were palpated, and EMG activity was measured in 27 episodic tension-type headache patients and 32 headache-free controls. All testing was done while the subjects were in a headache-free state. Muscle tenderness was positively associated with the diagnosis of tension-type headache. Headache subjects exhibited significantly higher levels of temporal EMG activity compared to controls, but EMG data were of little use in assigning individual subjects to diagnostic groups. Measures of muscle tenderness and hyperactivity were only weakly associated. Pericranial muscle tenderness and elevated EMG activity may index different aspects of abnormal muscle function.     

Mental Stress of Long Duration: EMG Activity, Perceived Tension, Fatigue, and Pain Development in Pain-Free Subjects

The study examined the relationship between pain development in the shoulder, neck, and facial regions and the EMG activity of underlying muscles, during prolonged exposure to a mental stressor. The subjective perception of tension and fatigue was recorded. Thirty-six subjects were exposed to a two-choice reaction-time test for 1 hour. Electromyographic (EMG) recordings were performed bilaterally over the frontalis, temporalis, splenius, and trapezius muscles. Pain and perceived tension were scored on a visual analog scale, and fatigue on a Borg scale. Pain development was most pronounced in the shoulder and neck region. There was a weak tendency of those reporting pain in the shoulder region to generate higher EMG activity in the trapezius relative to those with no shoulder pain at the end of the test. No such relationship was observed for the other muscles. Perceived tension during the test was weakly related to pain and strongly related to fatigue at the end of the test, but not to EMG level. It is concluded that the mean level of the EMG response is of little consequence for pain development during stressful conditions. It is argued that other physiological responses such as prolonged activity in low-threshold motor units, whereby the surface EMG response can serve as a marker, can be important for shoulder pain originating in the trapezius muscle.     

The local and referred pain from myofascial trigger points in the temporalis muscle contributes to pain profile in chronic tension-type headache

OBJECTIVE: To assess the local and referred pain areas and pain characteristics evoked from temporalis muscle trigger points (TrPs) in chronic tension-type headache (CTTH). METHODS: Thirty CTTH patients and 30 age and sex-matched controls were studied. A headache diary was kept for 4 weeks to substantiate the diagnosis and record the pain history. Both temporalis muscles were examined for the presence of myofascial TrPs in a blinded fashion. The local and referred pain intensities, referred pain pattern, and pressure pain threshold were recorded. RESULTS: Referred pain was evoked in 87% and 54% on the dominant and nondominant sides in CTTH patients, which was significantly higher (P<0.001) than in controls (10% vs. 17%, respectively). Referred pain spread to the temple ipsilateral to the stimulated muscle in both patients and controls, with additional referral behind the eyes in most patients, but none in controls. CTTH patients reported a higher local [visual analog scale (VAS): 5.6+/-1.2 right side, 5.3+/-1.4 left side] and referred pain (VAS: 4.7+/-2 right side, 3.5+/-2.8 left side) intensity than healthy controls (VAS: 0.8+/-0.7 right side, 0.7+/-0.7 left side for local pain; and 0.3+/-0.2 right side, 0.4+/-0.3 left side for referred pain) in both temporalis muscles (both, P<0.001). The local and referred pain areas were larger in patients than in controls (P<0.001). Twenty-three out of 30 CTTH patients (77%) had active TrPs in the temporalis muscle leading to their usual headache (17 patients on the right side; 12 on the left side, whereas 6 with bilateral active TrPs). CTTH patients with active TrPs in either right or left temporalis muscle showed longer headache duration than those with latent TrPs (P=0.004). CTTH patients showed significantly (P<0.001) lower pressure pain threshold (1.1+/-0.2 right side, 1.2+/-0.3 left side) as compared with controls (2.5+/-0.5 right side, 2.6+/-0.4 left side). CONCLUSIONS: In CTTH patients, the evoked local and referred pain from active TrPs in the temporalis muscle and its sensory characteristics shared similar patterns as their habitual headache pain. Local and referred pain from active TrPs in the temporalis muscles may constitute one of the sources contributing to the pain profile of CTTH.