Factors Predictive of Enlargement of Dissecting Aneurysms in the Vertebral Artery.

OBJECTIVE

To elucidate the incidence rate of enlargement of vertebral artery dissecting aneurysms (VADAs) during the acute phase and factors associated with enlargement.

METHODS

Of 115 patients with unilateral intracranial vertebral artery dissection who did not experience subarachnoid hemorrhage, 64 with the pearl sign of vertebral artery dissection (VADA without stenosis) participated in the study. We performed initial magnetic resonance imaging to diagnose VADA and subsequent magnetic resonance imaging to evaluate VADA enlargement. The presence of a hyperintense intramural signal was confirmed using T1-weighted three-dimensional turbo spin-echo imaging. Enlargement of VADAs between the initial and subsequent examinations was evaluated via magnetic resonance angiography and defined as the end point. We studied the rate of VADA enlargement using Kaplan-Meier curve analysis. After independent variables were determined, the Cox proportional hazards model was applied in multivariable analysis to identify the factors significantly associated with VADA enlargement.

RESULTS

Of 64 patients (mean age, 55.7 ± 13.0 years; 44 men and 20 women), 15 exhibited VADA enlargement. Kaplan-Meier curve analysis indicated that 24.8% of VADA enlargements were detected 30 days after initial magnetic resonance imaging. The Cox proportional hazards model revealed that young age (hazard ratio 0.953, P = 0.043) and the presence of hyperintense intramural signal (hazard ratio 2.841, P = 0.033) were significantly associated with VADA enlargement.

CONCLUSIONS

VADAs enlarged by approximately 25% until day 30 after the initial examination. Younger age and the presence of hyperintense intramural signal were significantly associated with VADA enlargement.