Using questionnaire data from two recent surveys, headache sufferers were classified as having either migraine, episodic, or chronic tension-type headache using the International Headache Society criteria. Of 410 subjects with a headache history of 2 years or more, 147 or 35.9% were assigned Code 1.7 (migrainous disorder not fulfilling the above criteria) or Code 2.3 (headache of the tension-type not fulfilling above criteria). In 79 of these 147 subjects (53.7%), either of the above codes would have been equally valid. Separate scores for "migraine" and "tension" symptoms may provide a way to handle this overlap and aid in choosing optimal therapy.

In a questionnaire survey we determined the prevalence of visual symptoms and eye strain factors in a group of chronic headache sufferers as compared with age- and sex-matched controls. The visual symptoms studied were those not specific for headache, i.e., sensitivity to light and blurred vision. Sensitivity to light in the absence of headache was reported by 27.8% of controls and 44.7% of headache sufferers (p less than 0.05). The latter figure increased to 71.3% when headache was actually present (p less than 0.001). Blurred vision occurred in 13.5% of controls and 7.4% of headache sufferers (not significant). In the presence of headache, the latter figure increased to 44.7% (p less than 0.01). Of the eye strain factors studied, bright light was reported to precipitate headache in 29.3% and to aggravate it in 73.4%. For reading, these figures were 16.0% and 55.3%, respectively; for working at the computer screen, 14.5% and 31.3%; and for watching television, 6.4% and 27.7%. We conclude that visual symptoms are more common in chronic headache and eye strain factors more important than is generally recognized.

In two headache questionnaire surveys we inquired about the occurrence of headache in the mothers, fathers, siblings and children of the respondents. In total, 633 people completed valid questionnaires, 260 in the first survey and 373 in the second. The hypothesis was that familial headache occurrence would be positively associated with headache frequency. In each survey, the regression of headache frequency on the number of parents having headache was highly significant. Neither sex nor the sibling and children variables were significant predictors. In the cross-tabulations of the parental occurrence of headache with headache frequency we saw a clear "break-point" between the "no headache" and the headache frequency categories studied. For the final analyses the dichotomy "headache/no headache" was related in fourfold tables to headache occurrence in the father and the mother separately, and to the number of headache parents. The positive associations were not simply due to the large number of migraine cases since they remained after removing the migraineurs.