[Electrophysiologic investigations in migraine]

This article is a critical review of standard electroencephalography (EEG), brain mapping, evoked potential, and electromyography (EMG) studies carried out in various forms of migraine during and between attacks. With the exception of contingent negative variation, the exteroceptive silent period of the temporalis muscle, and possibly fast activity in response to visual stimuli, which are useful for the differential diagnosis of functional headache, the main value of electrophysiologic studies is to provide insight into the pathophysiology of the disease. Results of the different methods consistently indicate that the brain of migraine patients is characterized by hypersensitivity to some forms of stimuli between attacks and by, often focal, hypoactivity during attacks.