Spontaneous symptomatic intracranial vertebrobasilar dissection: initial and follow-up imaging findings.

PURPOSE: To evaluate initial radiologic findings of symptomatic intracranial vertebrobasilar dissections (VBDs) as well as the results at follow-up imaging of dissections that are conservatively managed.
MATERIALS AND METHODS: The respective institutional review boards approved this retrospective study and waived the need for informed consent. The initial radiologic findings of 210 patients with 230 symptomatic intracranial VBDs were retrospectively evaluated (48 ruptured, 182 unruptured). Those patients had undergone conventional angiography as well as magnetic resonance imaging and/or computed tomographic angiography, so that angiographic shapes and pathognomonic findings (eg, intramural hematoma, intimal flap) could be reviewed. The primary angiographic shapes of the symptomatic intracranial VBDs were subdivided into three groups: (a) dilatation without stenosis, (b) pearl-and-string, and (c) stenosis without dilatation. Furthermore, the radiologic evolution of conservatively managed symptomatic intracranial VBDs was evaluated. The respective frequencies of the radiologic findings at initial and follow-up imaging studies were compared by using χ2 tests.
RESULTS: Primary shape differed significantly between ruptured and unruptured symptomatic intracranial VBDs. Most ruptured dissections presented with one of two main structures: dilatation without stenosis or pearl-and-string appearance. The primary shape of unruptured dissections was evenly distributed among the three types of findings. Intramural hematomas were most frequently found in the stenosis-without-dilatation group (42 of 60 [70%]), followed by the pearl-and-string group (27 of 90 [30%]). Intimal flap was most frequently found in the pearl-and-string group (21 of 90 [23%]), followed by the stenosis-without-dilatation group (eight of 60 [13%]). Follow-up results significantly differed by initial VBD shapes: Seventy-four percent (25 of 34) of the dilatation-without-stenosis group showed no change, whereas improvement was observed in 91% (39 of 43) of the stenosis-without-dilatation group (P<.05). Intracranial VBDs with intramural hematoma showed improvement in 63% (34 of 54) of cases, progression occurred in 20% (11 of 54), and only 17% (nine of 54) exhibited no change (P<.05).
CONCLUSION: Primary angiographic shapes of symptomatic intracranial VBDs differed between ruptured and unruptured lesions. The stenosis-without-dilatation lesions most frequently exhibited radiologic improvement at follow-up imaging, followed by pearl-and-string and dilatation-without-stenosis lesions. © RSNA, 2012.