Advances in understanding the mechanisms of migraine-type photophobia

Purpose of review Historically, photophobia was studied in patients and attempts to explain the underlying mechanisms have been speculative. Efforts to understand better the neural substrate of photophobia paved a way to the development of different animal models and the publication of several articles ( all in 2010) on the mechanism by which light exacerbates migraine headache. Recent findings Observations made in blind migraine patients devoid of any visual perception and blind migraine patients capable of detecting light have led to the discovery of a novel retinothalamo-cortical pathway that carries photic signal from the retina to thalamic trigeminovascular neurons believed to play a critical role in the perception of headache intensity during migraine. Evidence for modulation of the trigeminovascular pathway by light and identification of the pathway through which photic signals converge on the nociceptive pathway that mediates migraine headache provide first set of scientific data on the mechanism by which light intensifies migraine headache. Summary The findings provide a neural substrate for migraine-type photophobia. This may lead to identification and development of molecular targets for selective prevention of photophobia during migraine.