A migraine causes paroxysmal unilateral headaches accompanied by vomiting. Complex biochemical changes, for example, an increased amount of serotonin and prostaglandin in the blood plasma, provoke a short spasm of the intracranial vessels followed by a continuous expansion of the extracranial arteries. The spasm is the foundation of photopsia and other focal symptoms. The expansion of the vessels is the direct cause of headaches. In the case of a classical migraine, the attack begins with a transient (sometimes ophthalmic) scotoma. The aura lasting from several to 30 minutes is followed by a unilateral pain in the frontotemporal area. The pain is often felt in the head at large. The pain is usually accompanied by nausea and vomiting. The attack lasts several hours. Unlike a classical migraine (10 per cent of all migraine cases), ordinary migraine has no visual aura. It features a diffuse pain that arises in the morning and lasts several days. Rest provokes cephalalgia (a headache at the weekend). This migraine variant is characteristic of women suffering from overweight. Cases, during which the migraine attack is accompanied by hemiplegia, aphasia, ophthalmoplegia, are known as associated migraine. Frequency and seriousness of attacks vary greatly: 50 per cent of patients have attacks less than once per week. A migraine is a widespread disease affecting 5-10 per cent of the population. The disease usually begins during the period of adolescence or, though less often, during childhood.