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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The exteroceptive suppression (ES) of electrical activity in the temporal muscle is an inhibitory antinociceptive brain-stem reflex. We investigated whether aspirin can significantly modulate latencies or durations of the early (ES1) and late (ES2) exteroceptive suppression periods of electrical activity in the temporal muscle. Participating in the randomized double-blind crossover study were 20 patients with migraine without aura, 20 patients with tension-type headache, and 20 healthy subjects. ES1 and ES2 elicited by an electrical stimulus of 20 mA lasting 0.2 msec were recorded during maximal voluntary contraction of the mastication muscles before and 30 min after medication. In a randomized and double-blind fashion half of the subjects were given 1200 mg of aspirin in the form of an effervescent solution and the other half were given an identically tasting solution without aspirin. One week later the experiment was repeated with the substances exchanged in crossover fashion. The administration of placebo as well as aspirin caused a highly significant increase in ES1 duration (P less than or equal to 0.001). While aspirin caused a highly significant increase in ES2 duration (P less than or equal to 0.001) the taking of placebo showed no significant effect on ES2 duration. In giving aspirin as opposed to the placebo, there was a significant interaction between groups and drug effect on the latency of ES1; whereas in migraine patients and in patients with tension-type headache the latency of ES1 was reduced by administration of aspirin, it was increased in healthy subjects (P less than or equal to 0.05). Neither aspirin nor placebo significantly varied the ES2 latency.(ABSTRACT TRUNCATED AT 250 WORDS)
Pain 1992 Feb
PMID:Acetylsalicylic acid activates antinociceptive brain-stem reflex activity in headache patients and in healthy subjects. 158 37

Inhibition of the second exteroceptive suppression of temporalis muscle activity (ES2) produced by a preceding electrical stimulus applied at the index was studied in patients suffering from migraine without aura (MO), chronic (CTH) or episodic (ETH) tension-type headache. Each patient group comprised of 12 subjects was compared to a group of healthy controls. Mean duration of unconditioned ES2, measured on 10 averaged rectified responses after labial stimulation at a 0.1 Hz frequency, was reduced in CTH only. From stimulation intensities of 20 mA onward, peripheral-induced inhibition of temporalis ES2 was significantly more pronounced in both subtypes of tension-type headache compared to migraineurs or controls. After an index finger stimulus of 20 mA, temporalis ES2 was abolished in 83% of CTH, 67% of ETH, 25% of MO patients and 8% of controls, whereas unconditioned ES2 was present in all patients. Among 9 ETH patients with normal (> or = 32 msec) unconditioned ES2, 5 had total disappearance of ES2 after a 20 mA index stimulation. These results demonstrate that peripheral conditioning at 20 mA increases the diagnostic sensitivity of ES2 studies. They suggest that the changes observed in tension-type headache are due to hyperexcitability of the reticular nuclei which inhibit the medullary inhibitory interneurons mediating ES2.
Pain 1994 Dec
PMID:Reduction of temporalis exteroceptive suppression by peripheral electrical stimulation in migraine and tension-type headaches. 770 6

The brainstem mediated inhibitory reflex of the m. temporalis was investigated on average 3 days after the accident in 61 patients (f = 36; m = 25; mean age = 28 years +/- 9 SD) who presented an acute cervico-cephalic syndrome with posttraumatic headache and neck pain following acute whiplash injury but without neurological deficits, bone injury of the cervical spine or combined direct head trauma. We postulated a disturbed reflexive temporalis muscle inhibition in patients with 'whiplash cephalalgia', as has previously been reported for classical muscle tension headache. Latencies and durations of the early and late exteroceptive EMG suppression (ES1 and ES2) and the interposed EMG activity (IE) of the voluntarily contracted right temporalis muscle following ipsilateral stimulation of V/2 + 3 afferents were recorded. The reflex data were compared to a cohort of 69 age and sex matched normal subjects (f = 37; m = 32; mean age = 28 years +/- 7 SD). The following significant reflex changes were found in patients: a shortened duration of ES2 with delayed onset and premature ending, a slight prolongation of ES1 and IE, a delayed onset of IE and a diminished ratio of ES2:ES1 and ES2:IE. We conclude that the abnormality of the antinociceptive reflex is based on a transient dysfunction of the brainstem mediated reflex circuit following the acceleration trauma, which can be considered a neurophysiological correlate of the posttraumatic cervico-cephalic pain syndrome and may be useful as a 'biological marker' in monitoring the time course of recovery from pain.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Pathological jaw opening reflex after whiplash injury]. 801 31

The duration of the late exteroceptive suppression period (ES2) of temporal muscle EMG activity has been reported to be reduced in patients suffering from chronic tension-type headache. Methods of recording and analysing ES2 have varied between centers and reproducibility of results within subjects, although insufficiently studied, has generally been poor. ES2 was investigated in 30 healthy subjects, using a computerized technique of recording, rectifying and averaging the EMG signals. Hour to hour and week to week variations of ES2 durations were calculated, and the influence of pain during a cold pressor test and of sustained muscle contraction on ES2 durations was investigated. The intra-individual variation of ES2 durations was 16.0% from hour to hour and 20.7% from week to week. The inter-individual variation was 36.7%. The present method for analysis of ES2 periods proved to be reliable, as the intra-observer variation was 4.2% and the inter-observer variation 4.6%. ES2 periods were significantly shorter on the first compared to the second day of examination (p = 0.006) and during experimental pain (p = 0.0005). We recommend the use of the computerized average technique in future studies and caution against the dependence of results upon factors such as conditioning and pain.
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PMID:Exteroceptive suppression periods in jaw-closing muscles. Variability and relation to experimental pain and sustained muscle contraction. 835 76

The second exteroceptive suppression of masseter muscle activity (ES2) and tenderness in pericranial muscles were evaluated in 112 young adults who met IHS criteria in the following diagnostic classifications: 31 chronic tension headache, 31 episodic tension headache, 33 migraine without aura and 17 migraine with aura. An additional 31 subjects served as controls. Pericranial muscle tenderness better distinguished diagnostic subgroups and better distinguished recurrent headache sufferers from controls than did masseter ES2. Chronic tension headache sufferers exhibited the highest pericranial muscle tenderness, and controls exhibited the lowest tenderness (P < 0.01). All chronic tension headache sufferers exhibited muscle tenderness in at least one of the pericranial muscles evaluated, while tenderness was exhibited by 52% of controls. The association between pericranial muscle tenderness and chronic tension headache was independent of the intensity, frequency, or chronicity of headaches. Our findings raise the possibility that pericranial muscle tenderness is present early in the development of tension headache, while ES2 suppression only emerges later in the evolution of the disorder.
Pain 1996 Mar
PMID:Central and peripheral mechanisms in chronic tension-type headache. 878 11

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.
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PMID:Exteroceptive suppression of temporal muscle activity is normal in chronic tension-type headache and not related to actual headache state. 904 62

Although reflexes in human jaw muscles have been extensively studied, the neurotransmitters involved in the regulation of these reflexes are not well known. The aim of the present study was to investigate whether amitriptyline, a combined serotonin and noradrenaline re-uptake inhibitor, modulates the late exteroceptive suppression period (ES2) of temporal muscle activity in chronic tension-type headache. ES2 was recorded with a previously evaluated method and assessed by a blinded observer in 35 patients with chronic tension-type headache. Thereafter, ES2 was recorded in 27 of these patients during a double-blind, placebo-controlled, 3-way crossover trial investigating the prophylactic effect of amitriptyline, the selective serotonin re-uptake inhibitor citalopram, and placebo. ES2 duration was significantly shorter during treatment with amitriptyline than during placebo, P = 0.02, while ES2 duration only tended to be shorter during treatment with citalopram, P = 0.34. ES2 was not significantly correlated to the prophylactic effect of amitriptyline or to a range of clinical and experimental pain parameters. Our results demonstrate that amitriptyline reduces ES2 and indicate that ES2 is modulated by serotonergic as well as noradrenergic neuronal pathways.
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PMID:Amitriptyline, a combined serotonin and noradrenaline re-uptake inhibitor, reduces exteroceptive suppression of temporal muscle activity in patients with chronic tension-type headache. 891 95

The exteroceptive suppression period (ES) of the temporalis muscle activity is a trigemino-trigeminal brain stem reflex. It will be elicited most when stimulating trigeminal sensory afferents by painful stimuli and typically leads to a biphasic interruption of voluntary muscle activity. The first phase of decreased voluntary activity is called the early exteroceptive suppression period (ES1), the second, the late exteroceptive suppression period (ES2). Between these two suppression periods a phase of increased muscle activity, the so-called facilitation period (FP), can be seen. This phenomenon can be modulated by different stimulating parameters and usually, in healthy subjects, this normal pattern of the exteroceptive suppression can be elicited regularly. The reflex answer may occur at low non-painful stimulus intensities; typically, however, it appears to be most pronounced with high-intensity stimuli. Because of the obvious relationship between stimulus intensity, pain perception and reflex, the reflex is regarded as an antinociceptive reaction. The absence of an inhibition of motor activity can be visualized, for example, in hemimasticatory spasm or dystonic disorders. However, above all the ES nowadays attracts most attention as a tool to analyse different pain syndromes. One main advantage of this method in man is the ability to evaluate certain antinociceptive brain stem mechanisms functionally by means of a simple noninvasive technique. A large number of results have been obtained showing that chronic pain syndromes such as chronic tension-type headache and migraine cause changes within the normal ES recording pattern. Furthermore, some substances used in pain therapy, such as serotonin agonists or antagonists, acetylsalicylic acid or naloxone, may also alter the general appearance of the ES. This review will summarize different parameters that influence the ES reflex answer. Furthermore, the diagnostic value of changes in the ES for pathophysiological processes regarding pain perception and processing in certain pain syndromes will be discussed.
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PMID:[Exteroceptive suppression of activity of the temporal muscle. Principles and applications]. 903 58

Therapeutic mechanisms hypothesized to underlie improvements in tension headache activity achieved with combined relaxation and electromyographic (EMG) biofeedback therapy were examined. These therapeutic mechanisms included (1) changes in EMG activity in frontal and trapezii muscles, (2) changes in central pain modulation as indexed by the duration of the second exteroceptive silent period (ES2), and (3) changes in headache locus of control and self-efficacy. Forty-four young adults with chronic tension-type headaches were assigned either to six sessions of relaxation and EMG biofeedback training (N = 30) or to an assessment only control group (N = 14) that required three assessment sessions. Measures of self-efficacy and locus of control were collected at pre- and posttreatment, and ES2 was evaluated at the beginning and end of the first, third, and last session. EMG was monitored before, during, and following training trials. Relaxation/EMG biofeedback training effectively reduced headache activity: 51.7% of subjects who received relaxation/biofeedback therapy recorded at least a 50% reduction in headache activity following treatment, while controls failed to improve on any measure. Improvements in headache activity in treated subjects were correlated with increases in self-efficacy induced by biofeedback training but not with changes in EMG activity or in ES2 durations. These results provide additional support for the hypothesis that cognitive changes underlie the effectiveness of relaxation and biofeedback therapies, at least in young adult tension-type headache sufferers.
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PMID:Change mechanisms associated with combined relaxation/EMG biofeedback training for chronic tension headache. 928 53

Changes of the second suppressive period (ES2) of the exteroceptive suppression of the temporalis muscle activity are found in patients with chronic tension-type headache (TTH) and are suggested to reflect an abnormal endogenous pain control system. We investigated whether similar changes are found in patients with the fibromyalgia syndrome (FMS) that is also believed to result from disturbed central pain processing. The ES2 values of 27 patients with FMS were compared with those of 18 patients with TTH and 40 healthy volunteers. The duration of ES2 (+/-SD) in FMS patients was 30.6+/-7.5 ms and was not significantly different from the control group (33.1+/-7.8 ms), whereas it was significantly shortened in TTH patients (22.9+/-11.5 ms). Our results indicate that, despite similar concepts on the pathophysiology of the two chronic pain disorders, there are no comparable changes of this brain stem reflex activity in FMS.
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PMID:Exteroceptive suppression of temporalis muscle activity in patients with fibromyalgia, tension-type headache, and normal controls. 980 49


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