• clinical outcome;
  • infarct volume;
  • ischaemic stroke;
  • leptomeningeal collateralization;
  • penumbra;
  • transcranial Doppler


Anterior cerebral artery flow diversion, measured by transcranial Doppler ultrasound, is correlated with leptomeningeal collateral flow on digital subtraction angiography in the setting of middle cerebral artery occlusion. We aimed to assess the influence of flow diversion as a marker of leptomeningeal collateralization on infarct size and penumbral volume.


We assessed consecutive patients presenting within six-hours of ischaemic stroke. Anterior cerebral artery flow diversion, defined as ipsilateral mean velocity of at least 30% greater than the contralateral artery, was used as the Doppler index of leptomeningeal collateralization. Multivariable regression analysis was performed to assess the impact of anterior cerebral artery flow diversion, controlling for other important clinical variables. Leptomeningeal collateralization was also graded on computed tomography angiography. Infarct core and penumbral volumes were defined using computed tomography perfusion thresholds of cerebral blood volume and mean transit time. Infarct volume, reperfusion, and vessel status were measured at 24 h using magnetic resonance techniques.


Fifty-three patients qualified for analysis. Anterior cerebral artery flow diversion was associated with good collateral flow on computed tomography angiography (P < 0·001) and was an independent predictor of admission infarct core volume (P < 0·001), and 24 h infarct volume (P < 0·001). The likelihood of a favourable outcome (modified Rankin Score 0–2) was higher (odds ratio = 27·5, P < 0·001) in those with flow diversion.


Anterior cerebral artery flow diversion indicates effective leptomeningeal collateralization as measured by computed tomography angiography, and independently predicts acute infarct size and 90-day clinical outcome. Flow diversion appears to provide penumbral perfusion, offering some protection against infarct expansion. Acute bedside transcranial Doppler assessment of flow diversion aids prognostication and therapeutic decision making in anterior circulation stroke.