Transient neurological symptoms during contrast transcranial Doppler right-to-left shunt testing in patients with cryptogenic neurological disease.

Background: Paradoxical embolization from right-to-left shunt (RLS) resulting in neurological events is well described and patients with cryptogenic neurological disease are commonly evaluated for this condition. In the course of testing for RLS by bubble contrast transcranial Doppler (TCD), we observed that some patients developed transient neurological symptoms. This report describes our findings.

Methods: We performed diagnostic TCD on 445 consecutive patients with cryptogenic neurological disease (cerebral vascular accident, 21%; transient ischemic attack, 30%; migraine, 48%; and abnormal magnetic resonance brain imaging, 68%). Immediately following the procedure, patients were questioned about neurological symptoms.

Results: One hundred and sixty-three (37%) of the 445 patients had absent or minimal shunting (Spencer grades 0-1) and 233 of 445 (52%) had severe RLS (Spencer grades 4-5+). One or more TCD-associated neurological symptoms (TCD-SX) developed in 95 of 445 (21%) of the patients. Compared to patients with absent or minimal shunting, patients with shunt grades 2-5+ were two and one half times more likely to develop TCD-SX (18/164 [11%] vs. 77/283 [27%], P < 0.001). TCD-SX were fourfold more common among patients with a history of migraine compared to history-negative subjects (35 vs. 8.7%, P < 0.0001).

Conclusions: Diagnostic bubble-contrast TCD provoked transient neurological symptoms. The symptoms correlated with the severity of RLS and were more common in migraine patients, suggesting that migraine patients are sensitized to chemical and/or microembolic shunt factors. There was no significant residual morbidity, and bubble-contrast echocardiograph continues to be a safe and valuable diagnostic procedure.