Transcranial Doppler study of cerebral arteriovenous malformations after gamma knife radiosurgery

The aim of this study was to evaluate the clinical value of the Transcranial Doppler (TCD) in follow-up examinations after gamma knife radiosurgery (GKS) for arteriovenous malformations (AVM). We performed TCD after GKS in 18 patients who had cerebral AVMs to evaluate the hemodynamic effects of the procedure. Ten patients underwent TCD within 12 months after GKS, and eight between 12 and 24 months. The mean blood velocity (Vm) and pulsatility index (PI) were primarily analyzed in the feeding arteries (FAs) and non-FAs. Fifteen healthy volunteers served as control patients. The Vm values in the FAs after GKS ranged from 31 cm/s to 90 cm/s, with PI values ranging from 0.48 to 1.03. The Vm values in the comparable normal arteries ranged from 28 cm/s to 87 cm/s, and the PI values in these arteries ranged from 0.62 to 1.02. The Vm and PI values in every FA in all patients were normal compared to the values in the non-FAs (p=0.67 and 0.38, respectively). Our results suggest that AVM vessels with high Vm and low PI values return to normal as the nidus of the AVM is obliterated after GKS. Although there was a trend toward a reduction of the Vm values after obliteration, this trend was not significant, except when the < 12 month subgroup was compared to the 12-24 month subgroup. In our limited study, TDC proved to be a reliable, safe and non-invasive method to monitor the outcome of GKS for cerebral AVMs.