Prevalence and extent of right-to-left shunt in migraine: a survey of 217 Chinese patients

Background Recently, contrast‐enhanced transcranial Doppler (cTCD) studies have shown that right‐to‐left shunt (RLS) may be a risk factor for migraine in Westerners; however, limited data in the literature describes the prevalence of RLS in Chinese patients with migraine. Objective To assess the prevalence of RLS in patients with migraine in China and to evaluate the relationship between the extent of RLS and migraine. Methods A total of 217 consecutive patients with a diagnosis of migraine and 100 volunteers were recruited. cTCD was used to assess the prevalence and the extent of RLS in all subjects. Results In the migraine group, the rate of positive RLS was 44.2% (96/217), with 23.5% (51/217) of these being large. In the healthy group, 28.0% (28/100) were positive for RLS overall, and 5.0% (5/100) were large (P = 0.006; P