Prevalence of vertebral artery dissection in Wallenberg syndrome: neuroradiological analysis of 93 patients in the Tohoku District, Japan.

To assess the prevalence of vertebral artery dissection in Wallenberg syndrome (lateral medullary syndrome), records of 93 patients (70 men, 21 women, and 2 patients not identified by gender; mean age at ictus, 58.1 years) with symptoms of Wallenberg syndrome who underwent MRI and/or vertebral angiography were reviewed retrospectively. Study items included the following: (A) headache; (B) arterial intramural hematoma on T1-weighted images as an MR finding; and (C) double lumen, intimal flap, pearl and string sign, and string sign as angiographic findings. These abnormal findings suggesting vertebral artery dissection were scored as 1 or 2 points. According to his or her total score, each patient was classified as "definite dissection." "probable dissection," "suspected dissection," or "no dissection." Twenty-three of 93 patients were classified as "definite dissection," 23 as "probable dissection," 27 as "suspected dissection," and 20 as "no dissection." The frequency of definite or probable dissection in Wallenberg syndrome was estimated at 50% or more. Thus, vertebral artery dissection is a frequent cause of Wallenberg syndrome.