Tenderness and pain thresholds in pericranial muscles were studied in a general population. A random sample of 1000 adults aged 25-64 years was drawn as part of the Glostrup Population Studies, and 740 adults were examined. This study was part of a multifacetted, epidemiological study of different headache disorders according to the new headache classification. Manual palpation and pressure pain threshold with an electronic pressure algometer were performed by observers blinded to other information such as the person's history of headache, previous illness and mental state. The muscles most commonly tender to manual palpation were the lateral pterygoid (55%), the trapezius (52%), and the sternocleido-mastoid muscles (51%). Females were more tender than men in all the muscles examined by manual palpation. In total, the young age group was more tender than the old age group (P = 0.03). Pressure pain thresholds on temporal muscles showed lower thresholds in women than in men (P less than 10(-3)), and in the total population thresholds increased with age (P less than 0.05). No side-to-side difference in tenderness by manual palpation was found, while the right side showed increased pain thresholds in right-handed individuals (P less than 10(-4)). No side-to-side difference was found in left-handed persons. This study provides data about the normal population and forms the necessary basis for evaluating the importance of muscle tenderness in headache subjects and other selected groups.

SYNOPSIS To analyse from which extracranial tissues the pain of common migraine arises, 50 patients with typical common migraine were studied during the attack. Systematic recording of pain in 18 regions of the head and neck was followed by systematic palpation of 26 cranial and neck muscles and tendon insertions. All 50 patients were tender, and tenderness corresponded to pain in all but 2 cases. The most frequent sites of tenderness were: sternocleidomastoid, anterior temporal, neck and shoulder muscles, the coronoid process and occipital insertions. Referred pain was found in 73% of patients. Major pathways were sternocleidomastoid to temporofrontal area or occiput, occiput to vertex or temporofrontal area, neck to vertex or brow. The most tender spots were infiltrated with lidocaine 1.5% or saline double blindly. Results were judged clinically and by visual analog scales. 2648 patients were symptom free after 70 minutes which is significantly better than with medical treatment (p<0.01). There was no difference between lidocaine and saline. The study demonstrates that pericranial muscles and tendon insertions are important for common migraine pain.

Oral function was evaluated in a group of 13 patients with muscle contraction headache (MCH), 7 patients with common migraine (CM) and 18 patients with 'combination headache' (CM + MCH) and in a control group of 25 normal persons who had never had a headache. Malocclusion and loss of molars were rare in both groups. Impaired denture function and joint disturbances were more frequent in the headache patients but not significantly so. Clenching and grinding teeth and tongue pressure were all significantly more common in headache patients. Tenderness of pericranial muscles was present in all headache patients with severity increasing in the order CM, MCH, CM + MCH; it was absent in all the controls. On the average 9 tender spots were found per patient. Pressure on tender spots evoked pain in other areas (referred pain) in 29 of 38 headache patients. The abnormal tonic hyperactivity in the masticatory muscles and the neck may be the cause of tenderness which again may be an important source of pain in these patients.

In a longitudinal study we compared clinical data on pain and tenderness and eJcctromyog-raphic recordings of posiural and maximal activity from 37 patients before and after treatment ol functional disorders of the masticatory system. Forty-lhree dental studetits served as controls. Treatment was followed by a concomitant decrease of pain, tenderness and postural activity. Musdc strength in terms of the activity during maximal bite in the iniercuspai position was not altered by treatment, but activation of the right and lefl anterior temporal muscles became more uniform. The relative postural loading of the elevators was assessed as their activity in percent of full effort. Fallowing treatment, loading in patients decreased significantly and became more symmetrical in the anterior temporal muscles. Loading also tended to decrease in the posterior temporal and masseter muscles. However, il still significantly exceeded postural activity in percent of full effort in the controls. Since treatment involved correction of the occlusion we conclude that the intermaxillary conditions of tooth contact during function play a role in the etiology of functional disorders and that the reduction of the relative postural loading of the eie\'ators of the patients due to this treatment contributed to their relief. The relatively high percentage of full efTort displayed as postural activity by the patients even after treatment may explain fluctuation of symptoms and signs offunctional disorders of the masticatory system. It also emphasizes the need for improved methods of treatment lo reduce the probability of recurrence.