Cryptogenic multiterritorial stroke with anti-U1 ribonucleoprotein positivity and steroid responsiveness: a diagnostic challenge

Abstract

Acute ischemic stroke is most commonly caused by atherosclerotic, cardioembolic, or small vessel disease; however, in patients presenting with multiterritorial infarcts and inconclusive routine evaluation, alternative etiologies such as autoimmune mechanisms should be considered. We report the case of a 52-year-old male who presented with acute-onset vertigo followed by progressive imbalance and left-sided incoordination. Neuroimaging revealed multiple acute infarcts involving both anterior and posterior circulation. Cardiac and vascular evaluation did not identify a definitive source of embolism. Autoimmune workup demonstrated positive antinuclear antibodies with anti-U1 ribonucleoprotein (RNP)/Sm positivity raising suspicion of an underlying autoimmune-mediated process despite the absence of overt systemic features. The patient showed limited improvement with standard antiplatelet therapy but demonstrated marked clinical recovery following corticosteroid therapy, suggesting a possible inflammatory or immune-mediated mechanism. This case highlights the importance of considering autoimmune causes in patients with cryptogenic multiterritorial stroke and suggests a potential role for immunosuppressive therapy in selected cases.