How can we treat photophobia in migraine?

Increased sensitivity to light (photophobia) is a hallmark of migraine which often precipitates headache attacks and handicaps patients by forcing them into a darkened room. Currently it is not known how to treat this stressing symptom and even two directly opposing treatment concepts exist: reduction of light exposure versus desensitisation via controlled exposure. The present proposal will generate the first comprehensive data about the best treatment approach by comparing both strategies directly in the same patients. Besides clinical evaluation, effects of both treatments on subjects brains will be monitored by functional magnetic resonance imaging (fMRI). With such data, a neurophysiologically based recommendation for future effective treatment of photophobia will become possible.

The KLI455 project "How can we treat photophobia in migraine?" investigated the research question, how extraordinary sensitivity to light stimuli (photophobia) can be best understood and best treated in migraine. A first important project step to achieve this, was non-invasive monitoring of brain activity during light exposure in migraine patients. For this the technique of functional magnetic resonance imaging (fMRI) was utilized, which allows a threedimensional observation of brain activities. To allow for reliable individual fMRI results, the first study phase implemented methodological fMRI improvements important for reliable individual patient diagnostics. Based on these methodological improvements, a second study phase allowed to investigate the major study question: is it possible to help photophobic patients with a light desensitization approach? Or is it only possible to help with the current empirical approach - avoiding light exposure? Pilot data from the australian research partner Prof. Paul Martin had already indicated, that adequately applied light desensitization might be a possible therapy. These behavioural data had been achieved via behavioural observations. Neurophysiological data (like fMRI observations) however, are currently missing. The major result of the research project was, that most likely 2 different groups of migraine patients exist, which respond differently to therapeutic light exposure. Group 1 is susceptible for "light therapy". Here, photophobia could be reduced and the brains overactivation to light stimuli could be decreased. The second group however, did not respond to "light therapy". In this group, photophobia persisted as did the brains overactivation to light stimuli. The major conclusion from our KLI455 results is, that future treatment of photophobia should be done via precision medicine. First a migraine patient should be tested whether he/she belongs to the group of light therapy responders or the group of non-responders. Based on this classification the most effective individual therapy should be given - either light desensitization or light avoidance.