Transcranial Doppler ultrasonographic changes after embolization of cerebral arteriovenous malformations

The authors assessed the potential role of transcranial Doppler ultrasonography (US) in monitoring hemodynamic changes induced by embolization of cerebral arteriovenous malformations. Transcranial Doppler US was performed in eight patients with such lesions before and after embolization with n-butyl cyanoacrylate [corrected]. Changes in mean flow velocity and pulsatility index were analysed in all feeding and nonfeeding arteries. Anatomic and hemodynamic observations were also correlated with the results of digital subtraction angiography. A consistent trend was observed in all treated feeding arteries after embolization: the flow velocity decreased by a mean of 26% or 33 cm/s (p = 0.01, paired t-test), and the pulsatility index increased by a mean of 27% or 0.15 (p = 0.005). Although these changes did not correlate with the degree of angiographic reduction of the nidus (r = -0.31), they were most marked in malformations with a lower Spetzler grade or a higher degree of shunt obliteration. After embolization, recruitment of untreated feeding arteries was documented in two cases and a decrease in the "steal effect" from contralateral nonfeeding arteries in three. Changes in the nonfeeding arteries ipsilateral and contralateral to the malformation were variable. The authors conclude that transcranial Doppler US is a convenient and reliable method to evaluate quantitatively the hemodynamic effects of embolization of cerebral arteriovenous malformations.