Hemodynamic Changes in Arteriovenous Malformations After Radiosurgery: Transcranial Doppler Evaluation

OBJECTIVE: To monitor hemodynamic changes using transcranial Doppler (TCD) in patients with an arteriovenous malformation (AVM) after Gamma Knife surgery (GKS). METHODS: The study comprised 22 patients (17 men and 6 women, mean age 42 years, range 18-69 years) with an unruptured AVM fed by only the middle cerebral artery (MCA) or its branches. Serial TCD profiles from proximal MCAs were analyzed and correlated with treatment outcome. RESULTS: Baseline TCD measurements (presented as means +/- standard deviations) revealed significantly higher mean blood flow velocity (Vm) and lower mean pulsatility index (PI) in MCAs ipsilateral to AVMs than in contralateral MCAs (Vm 102 cm/s +/- 29 vs 66 cm/s +/- 16, P < 0.05; PI 0.63 +/- 0.10 vs 0.84 +/- 0.10, P < .05). No correlation was found between AVM volumes and hemodynamic indices. Vm values in ipsilateral MCAs were lower at 6 months (88 cm/s +/- 26) after GKS than at baseline (P < 0.05). At 2 years after GKS, a further decrease in mean Vm and an increase in mean PI were observed in ipsilateral MCAs, which then approximated the values of contralateral MCAs (Vm 71 cm/s +/- 30 vs 61 cm/s +/- 11, P = 0.16; PI 0.76 +/- 0.17 vs 0.83 +/- 0.14, P = 0.15). Cerebral angiography (CAG) at the same time revealed total obliteration of AVMs in 11 patients. Changes in Vm and PI values were found to be correlated with the completeness of obliteration. However, no correlation was found between baseline TCD measurements and level of obliteration. CONCLUSIONS: Normalization of hemodynamic indices measured by TCD was found to be correlated with AVM obliteration after GKS. However, significant hemodynamic improvements may develop after GKS before obvious obliteration by anatomic imaging.