Conclusions: Changes in the lumen of cervical arteries afflicted with spontaneous cervical artery dissection occur most frequently within the first few months after the dissection, but recanalization may occur up to 1 year later. Early recurrence is reasonably common but involves arteries previously unaffected by dissection. Recurrence of spontaneous cervical artery dissection is strongly associated with a family history of arterial dissection. Summary: It is generally acknowledged spontaneous cervical artery dissection (sCAD) is a highly dynamic process after the initial event. Information on recanalization and recurrence rates in patients with sCAD is limited, however. Although cervical artery mural hematomas are best detected by cervical magnetic resonance imaging (MRI) with T1 fat suppression, vascular ultrasound imaging is the test that is most frequently used to monitor patients with sCAD. In this study, the authors prospectively monitored consecutive patients with MRI-proven sCAD by duplex ultrasound imaging daily in the hospital, monthly for the first 6 months after discharge, and every 6 months thereafter. The authors studied 105 sCADs in 76 patients. The mean follow-up was 58 months (range, 28-96 months). Of the 105 dissections in this study, 61 (58.1%) involved the internal carotid artery and 44 (41.9%) involved the vertebral artery. Four patients had multiple sCADs. Follow-up was available for 74 (103 vessels) of the 76 patients (97.3%). Complete and hemodynamically significant (<50% stenosis) recanalization rates were 51.4% and 20.4%. All but one of the complete recanalizations occurred within the first 9 months after the initial event. Early recurrences (in-hospital recurrence) were common, with a second sCAD occurring in 20 previously unaffected arteries. There were only two late recurrences (2.7%) at a site of a previous sCAD. Six patients had a family history of arterial dissection and all had a sCAD recurrence. Recurrence rate in patients without a family history of arterial dissection was much less, with only 16 arteries (22.8%) affected (P < .001). Comment: There are several interesting points here. First, although recurrence of sCAD is reasonably uncommon, it generally occurs early after the initial event and in a different cervical artery. The authors' early recurrence of 25% is much higher than previously suspected and may relate to the rigorous follow-up protocol in the study. The fact that late sCAD recurrence can happen in previously affected artery suggests recurrence after sCAD in the early and late periods may have different pathologies. Perhaps, as the authors point out, early recurrences are correlated with a transient arterial disorder, such as a vasculitis, while late recurrences may be indicative of underlying persistent connective tissue weakness. The high early recurrence rate suggests that aggressive treatment of sCADs, including control of double product and lowering blood pressure within the constraints imposed by the neurologic pathology, should be implemented.