Unique CT Perfusion Imaging in a Case of H a NDL : New Insight into H a NDL Pathophysiology and Vasomotor Principles of Cortical Spreading Depression

Background The etiology of HaNDL is not known. Recent neuroimaging studies have suggested that there may be altered cerebrovascular blood flow during acute episodes. However, what exactly these vascular changes represent and how they may relate to the overall pathogenesis of HaNDL is uncertain. Case A 42‐year‐old, right‐handed male, presented with acute aphasia and right arm weakness. Urgent CT/CT‐angiogram were normal except for an incidental hypoplastic right anterior cerebral artery (ACA) A1 segment. However, CT perfusion revealed global left hemisphere hypoperfusion in the range of oligemia. Also, the right ACA territory, supplied by the dominant left A1, shared the same pattern of hypoperfusion. Further investigations and clinical course were consistent with HaNDL. Discussion/Conclusions The pattern of global left hemispheric hypoperfusion seen in this case of HaNDL supports a hypothesis of secondary oligemia induced by a hemispheric wave of cortical spreading depression (CSD). However, the extension of hypoperfusion to the right ACA territory represents a phenomenon not previously reported in this field. We speculate that the direct spread of CSD‐induced vasomotor changes across the anomalous vasculature could account for this finding. This case provides a valuable contribution toward understanding HaNDL pathophysiology and in doing so may also yield broader implications regarding neurophysiological principles of CSD.