Imaging Review and Clinical Manifestations of Lacunar Stroke Syndromes.

Lacunar strokes are small subcortical infarcts that result from the occlusion of small perforating arteries, and they comprise about 25% of all strokes. Unlike other types of infarcts, lacunar strokes are primarily due to cerebral small vessel disease. Detection of acute lacunar infarcts may be challenging due to their small size, but it can be improved with clinical-radiologic correlation. Numerous mimics should also be kept in mind in the differential diagnosis. While lacunar infarcts are more often asymptomatic, they may manifest with distinct clinical syndromes. Five classic lacunar syndromes are commonly recognized: pure motor hemiparesis, pure sensory stroke, sensorimotor stroke, ataxic hemiparesis, and dysarthria-clumsy hand syndrome. Beyond these, numerous atypical lacunar syndromes such as internuclear ophthalmoplegia, isolated dysarthria, hemichorea and hemiballismus, and paramedian thalamic syndrome have been described. Each of these has a unique clinical manifestation linked to lesions in specific neuroanatomic pathways. The authors provide a comprehensive overview of lacunar strokes, emphasizing their diverse clinical manifestations and the crucial role of imaging in diagnosis of these infarcts. ©RSNA, 2026 Supplemental material is available for this article.