Pressure pain thresholds were assessed with an algometer (Somedic Inc.), over the forehead, temple and suboccipital region as well as over the Achilles tendon. A group of 32 patients suffering from chronic tension-type headache was compared to 20 healthy controls and to 10 migraineurs without aura. Although individual values were widely scattered, pressure pain thresholds were on average significantly lower in chronic tension-type headache, not only at pericranial sites but also over the Achilles tendon. Only 50% of these patients had one or more pericranial thresholds 1.5 S.D. below the mean of controls. After muscular biofeedback therapy, all pain thresholds were on average increased. Along with results obtained previously, the present data support the hypothesis that diffuse disruption of central pain-modulating systems, possibly due to a modified limbic input to the brain-stem, is pivotal in the pathophysiology of chronic tension-type headache.

The second exteroceptive silent period (ES2) of temporalis muscle was recorded on days 1 and 15 of the menstrual cycle in 17 women, 9 of whom suffered regularly from tension-type headaches during menstruation. Mean duration of temporalis ES2 was significantly shorter on day 1 of the cycle than on day 15. This difference was due to a marked menstrual reduction of ES2 in the headache subgroup. A positive correlation was found between ES2 durations and oestradiol/progesterone ratios. We hypothesize that the variations of ES2 during the ovarian cycle result from the modulatory effects of oestrogens on descending aminergic pathways that control excitability of inhibitory brainstem interneurons mediating exteroceptive suppression of jaw-closing motoneurons.

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