Wallenberg's lateral medullary syndrome: Diffusion-weighted imaging findings

Purpose: To investigate the efficacy of diffusion-weighted imaging in patients with Wallenberg's lateral medullary syndrome. Material and Methods: Thirteen patients with Wallenberg's lateral medullary syndrome were: examined with conventional and echoplanar diffusion-weighted magnetic resonance (MR) imaging in a 1.5 T magnetic resonance unit. MR examinations were obtained in the acute or subacute stage of clinical syndrome, and diffusion-weighted imaging (DWI) was considered to be positive for infarction when an increase in signal was seen on b=1000 s/mm(2) images in the posterolateral medullary localization. Results: DWIs were positive in 12 patients in the acute or subacute stages of this clinical syndrome. A false-negative result was obtained in only one patient examined within the first day, 10 h after onset of the symptoms. In the visual evaluation of the DWI, the contrast between normal and infarcted brainstem area was better in the high b-value images than in the apparent diffusion coefficient map images. Conclusion: DWI is a valuable technique for examining patients presenting with the signs and symptoms of Wallenberg's syndrome and high b-value images can provide complementary data to T2-weighted images. However, because most of our case group were: in either the acute or subacute stage, true sensitivity of the method in the hyperacute stage of the syndrome remains unclear.