The extent of right-to-left shunt fails to correlate with severity of clinical picture in migraine with aura.

Several investigations have documented an increased incidence of right-to-left shunt (RLS) in migraine with aura (MA) and have emphasised its role in the physiopathology of aura; so far, however, no data are available concerning a possible correlation between the extent of the RLS and the clinical picture of MA patients. To investigate the possible relationship between the extent of the RLS, revealed by the number of microbubbles (MB) detected during transcranial Doppler with IV injection of ultrasound contrast (TCDc), and the clinical characteristics of MA (age at first onset of migraine, mean annual frequency of attacks and mean duration of the aura phase), 30 consecutive patients with typical aura and migraine headache positive on TCDc evaluation for RLS were enrolled. Permanent RLS was found in 12 patients and latent RLS was found in 18 patients; of these, 6 had a high-grade RLS, 5 medium-grade RLS and 7 low-grade RLS. No correlation has been documented between the number of MBs and the clinical parameters of both patients with latent shunts and those with permanent ones, nor between the clinical parameters of the two groups of patients. These data show that RLS does not seem to affect the clinical manifestation of MA and that the extent of RLS fails to correlate with the severity of the clinical picture of the disorder.