|Migraine is one of the most prevalent forms of headache in the general population, and is particularly common among subjects seeking medical advice for their head pain. The prevalence of migraine is three times higher in women than in men and peaks in the age group, 30-39 years. Migraine is characterized by recurrent attacks of head pain, often unilateral, pulsating, of an intensity mild to severe, worsened by physical activity and lasting from 4 up to 72 hours The attacks are often accompanied by neurovegetative symptoms such as nausea, vomiting, photophobia and phonophobia In one third of migrainous patients, the attacks are preceded by an aura, characterized by reversible focal neurological symptoms that usually develop gradually over 5-20 minutes, and lasts for less than 60 minutes. Attacks of migraine vary widely in intensity, duration and frequency across patients, and also in the same patient over time. In some cases, migraine may present as a very disabling condition, able to impair working and social activities, but aside from that the disease has been long considered as benign.
The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.