Transorbital Doppler with carotid siphon monitoring detects right-to-left shunt effectively

Abstract

Background Transtemporal Doppler (TTD) with middle cerebral artery (MCA) is widely used for right-to-left shunt (RLS) detection. However, an alternative method for patients without suitable temporal bone windows should be established. The present study prospectively evaluated the effectiveness of transorbital Doppler (TOD) with carotid siphon (CS) monitoring in detecting RLS. Methods A total of 357 subjects with sufficient temporal bone windows underwent simultaneous TTD with MCA and TOD with CS. After injection of microbubbles, the numbers of artificial high-intensity signals were recorded at rest and after Valsalva maneuver. Results TOD with CS detected RLS in 146 patients. Sensitivity was 97.1%, specificity 95%, positive predictive value 92.5%, and negative predictive value 98.1%. The total positive rates for RLS detection by CS (40.9%) and MCA (37.8%) monitoring were comparable without significant difference, but TOD with CS detected significantly more grade 2 and 3 RLS than TTD with MCA (p = 0.001). The RLS rates of cryptogenic stroke patients was significantly higher than that of healthy controls, and RLS in cryptogenic stroke was remarkably higher than that in transient ischemia attack patients (p < 0.05). TOD with CS examined significantly more grade 2 and 3 RLSs than the MCA approach in the cryptogenic stroke patients (p = 0.037). Conclusion TOD with CS monitoring is able to detect RLS effectively in different populations including healthy subjects, cryptogenic stroke, transient ischemia attack, and migraine patients. In comparing to the TTD with MCA approach, TOD with CS monitoring could detect comparable rate of RLS, but more high grades of RLS.

Right‐to‐left shunt detection using transforaminal insonation of the basilar artery

“…The value of common carotid insonation for RLS detection has been suggested, but has yet to be evaluated in a study 18 . Transorbital Doppler and monitoring of the carotid siphon has also been investigated, with results showing similar excellent sensitivity and specificity when compared to standard TCD MCA monitoring (97% and 95%, respectively) 19 . However, it should be noted that these studies were not completed in patients with inadequate temporal bone windows and used standard TCD monitoring as the reference standard, which may not account for alternative causes of right to left shunt, including pulmonary shunts.…”