Abstract WMP83: Arterial Dissection: A Still Underestimated Cause Of Lateral Medullary Infarction

Introduction: Although the association between vertebral artery or posterior inferior cerebellar artery dissection and lateral medullary infarction (LMI) has been established, the actual prevalence of dissection among patients with LMI may still be underestimated. Methods: Consecutive patients with acute pure LMI admitted between 2010 and 2021 were included. High-resolution vessel wall MRI (VWMRI) and/or transfemoral cerebral angiography (TFCA) were performed in a part of patients and were regarded as gold standard tests for diagnosis of dissection. Factors associated with definite dissection based on VWMRI or TFCA findings were assessed. Risk scoring for dissection was created based on multivariate logistic regression and applied to estimate the number of possible dissection. Results: Eighty-seven LMI patients were eligible and 47 (54.0%) of them underwent VWMRI (n=43) and/or TFCA (n=7). Among these 47 cases, 24 were definite dissection. Three out of 40 patients without gold standard tests were diagnosed with definite dissection based on conventional MRI findings. Preceding headache and normal body weight were independently associated with dissection in LMI patients. A risk scoring which includes age, body mass index, and headache predicted dissection with 91.7% sensitivity and 69.6% specificity (area under the receiver operating characteristic curve, 0.889; 95% confidence intervals, 0.802-0.977) in our population. Additional nine out of 37 patients without gold standard tests nor diagnosis of definite dissection in conventional MRI could be considered as possible dissection based on the scoring. Definite and possible dissections together comprised 41.4% (n=36) of LMI in our study. Conclusions: Arterial dissection may be more prevalent among LMI patients than reported before. Thorough diagnostic effort for dissection is necessary based on scrutinizing risk stratification.