Classical migraine: symptoms between visual aura and headache onset.

The gap between the end of the visual aura and headache onset in classical migraine has been called the free interval. In a retrospective study of twenty-five migraineurs who had noted a gap, only three reported feeling normal at that time: twenty-two described alterations in mood, detachment from the environment or other people, fears, disturbances of speech or thought, or somatic symptoms. The interval lasted less than an hour in seventeen of the twenty-two but in five persisted for 1 to 5 hours. These symptoms suggest involvement of the frontal and temporal cortices as well as the hypothalamus; they do not conform to Leão's spreading depression or a vascular mechanism, but are in keeping with a diffuse cerebral process with focal manifestations.