Prolonged cerebral transit time in CADASIL: a transcranial ultrasound study.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary angiopathy caused by mutations in Notch3. Cerebral microvessels show an accumulation of granular osmophilic material in the vicinity of degenerating vascular smooth muscle cells. In this study, we measured the arteriovenous cerebral transit time (CTT) to identify changes related to the microangiopathy in CADASIL. CTT is the time that a contrast agent needs to pass from a cerebral artery to its corresponding vein. CTT was measured in 17 CADASIL individuals (mean age, 50.2+/-12.3 years) and an equal number of age- and sex-matched control subjects (mean age, 48.9+/-13.0 years) with transcranial color-coded duplex sonography. The intensity curves were recorded in the P2 segment of the posterior cerebral artery and the vein of Galen after injection of the ultrasound contrast agent Levovist. CTT was significantly prolonged in individuals with CADASIL (4.4+/-1.9 seconds) compared with control subjects (1.3+/-0.5 seconds, P<0.0001). This difference was also significant when only nondisabled CADASIL individuals (Rankin score=0, n=9) were analyzed (P<0.0001). There was a nonsignificant trend for a correlation between Rankin score and CTT (r=0.39, P=0.11). The prolonged CTT likely reflects microvascular changes in CADASIL. Measurements of the CTT may be used clinically to disclose small-vessel disease. Studies comparing CADASIL subjects with other patient populations seem warranted to determine possible differences in CTT between different types of small-vessel disease.