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 < 0.001). In patients having migraines with aura (MwA), 66.1% (39/59) were positive for RLS overall, and 37.3% (22/59) were large, which was significantly higher when compared with the healthy group (P < 0.001; P < 0.001); in patients having migraines without aura (MwoA), 36.1% (57/158) were positive for RLS overall, and 18.4% (29/158) were large, which was against significantly higher (P < 0.001; P = 0.003). In the MwoA group, the large RLS rate was also higher than in the healthy group (P = 0.002).

Conclusions: A close correlation has been documented between RLS and migraine, especially MwA, but these relationships exist only when the shunts were large.