Natural course of the acute unruptured intracranial vertebral artery dissections which show pearl-and-string sign

Introduction: Ruptured vertebral artery dissections frequently exhibit pearl-and-string signs, a characteristic also observed in many unruptured dissections. This study examines the natural course of 50 unruptured acute vertebral artery dissections presenting with pearl-and-string signs and compares them to 10 ruptured dissections of the same morphological pattern.

Methods: We reviewed 633 radiology reports of head and neck imaging studies that included the keyword 'dissection'. From these, 60 cases displaying pearl-and-string signs were identified from a total of 322 vertebral artery dissections. These cases were classified based on morphological characteristics, including fusiform versus bulbous dilatation, symmetry, degree of expansion, and the severity of stenosis at both ends of the dilation. The relationships between these factors and favorable anatomical recovery were then analyzed.

Results: Headaches were linked to subarachnoid hemorrhages in 10 cases with bulbous dilatations. In contrast, 50 unruptured cases had fusiform dilatations, with no subsequent hemorrhages except for two cases treated preventively. Most unruptured dissections (78.4%) improved on follow-up: 48.6% fully recovered, 29.7% retained smooth dilatation, 10.8% developed irregular stenotic segments, 8.1% became occluded, and 2.7% transformed into a saccular lesion. Smaller or hypoplastic vertebral arteries were more likely to occlude (p = 0.017). Mild distal stenosis was associated with improvement (p = 0.001).

Conclusion: Acute unruptured intracranial vertebral artery dissections with 'pearl-and-string' signs had benign courses, with most recovering spontaneously and no subsequent hemorrhages. Regular imaging follow-ups at one- to three-month intervals are recommended over immediate intervention.