Diffusion Weighted Imaging Findings in the Acute Lateral Medullary Infarction

BACKGROUND AND PURPOSE Negative findings on diffusion-weighted imaging (DWI) does not exclude the possibility of brainstem infarction, particularly in the acute stage of medullary lesion. Our aim was to investigate the false-negative rate of DWI in patients with acute lateral medullary infarction. METHODS We applied DWI to 26 patients with a clinical diagnosis of lateral medullary infarction within 72 h of the onset. We assessed relationships between initial DWI findings and time-to-MRI (the time between onset of symptoms and initial DWI), number of clinical symptoms and signs, and final lesion volume. RESULTS There were 8 cases (31%) of false negatives in the initial DWI results. The occurrence of false-negative DWI findings decreased significantly as the time-to-MRI increased (P=0.014). However, the false-negative rate was not significantly correlated with the number of clinical symptoms and signs or the final lesion volume. CONCLUSIONS The diagnosis of lateral medullary infarction should not be ruled out on the basis of early negative DWI. To confirm the lesion, follow-up DWI or further MRI should be performed in cases with early negative DWI results.