The purpose of the study is to evaluate the prevalence and extent of right-to-left shunt (RLS) in Chinese migraineurs, and the morbidity of silent cerebral infarction in migraineurs.

This is a prospective multicenter study of Chinese population. Participants (normal individuals without migraine and migraineurs) are included after standardized diagnostic procedures (TCD and c-TCD). For migraineurs with large RLS further examinations (c-TTE and brain MRI) are required. Up to 10 study sites nationwide will be needed to recruit the planned participant population during a 1-year period.

The information of each participants will be registered, including basic facts, the longitudinal headache history, frequency, location, quality, intensity, duration, accompanied symptoms, precipitating and exacerbating factors, with or without aura, MIDAS and HIT-6 questionnaire.

Inclusion Criteria:

• For group 1: Normal healthy individual without migraine.
• For group 2: Clinical history of migraine diagnosed by a neurologist according to the International Classification of Headache Disorders.

Exclusion Criteria:

• Subjects with stenotic intracranial or extracranial arteries or intracranial abnormalities diagnosed with TCD.

We detect RLS through contrast-enhanced transcranial Doppler (c-TCD). The normal individuals will be selected to group 1, while those who suffer from migraine will be selected to group 2. Patients of group 2 with large RLS are required to take TTE and brain MRI.