Self-reported photophobic symptoms in migraineurs and controls are reliable and predict diagnostic category accurately

Objectives.-To assess the reliability of self-reported photophobia across d ifferent patient populations and to examine how visual stress thresholds an d photophobic symptoms may be predictive of diagnosis. Background.-Relatively little is known about interictal photophobia in migr aine. In particular, the variability of photophobia across different patien t groups has not previously been studied, and a pathophysiological hypothes is to account for the symptoms is not agreed upon. Methods and Results.-Study 1 compared 99 self-selected Dutch patients and 1 01 headache-free controls using survey methods. Patients both with and with out aura were significantly more likely to report symptoms, such as the wea ring of sunglasses in normal daylight, consistent with interictal photophob ia. Study 2 replicated these findings in a series of consecutive referrals to a headache clinic in the United States. Study 3 used a specially designe d laboratory test to examine the threshold for visual stress in those patie nts who had participated in study 2, Visual stress thresholds were signific antly lower in patients than in controls. A discriminant function analysis of data from both studies 2 and 3 showed that diagnostic category (migraine ; control) could be predicted from photophobic symptoms and visual stress t hresholds at a level significantly better than chance. Conclusions.-We suggest that interictal photophobia is common in migraine a nd similar across different patient populations. One pathophysiological hyp othesis is that interictal photophobia is associated with cortical hypersen sitivity to stimulation. The predictive validity of interictal photophobic symptoms suggests that clinical diagnosis may be aided by questioning the p atient about light sensitivity in the period between attacks.