Lacunar stroke

Lacunar stroke or lacunar cerebral infarct (LACI) is the most common type of ischemic stroke, resulting from the occlusion of small penetrating arteries that provide blood to the brain's deep structures. Patients who present with symptoms of a lacunar stroke, but who have not yet had diagnostic imaging performed, may be described as having lacunar stroke syndrome (LACS). Much of the current knowledge of lacunar strokes comes from C. Miller Fisher's cadaver dissections of post-mortem stroke patients. He observed "lacunae" (empty spaces) in the deep brain structures after occlusion of 200–800 μm penetrating arteries and connected them with five classic syndromes. These syndromes are still noted today, though lacunar infarcts are diagnosed based on clinical judgment and radiologic imaging. Each of the five classical lacunar syndromes has a relatively distinct symptom complex. Symptoms may occur suddenly, progressively, or in a fluctuating (e.g., the capsular warning syndrome) manner. Occasionally, cortical infarcts and intracranial hemorrhages can mimic lacunar infarcts, but true cortical signs (aphasia, visuospatial neglect, gaze deviation, and visual field defects) are always absent in lacunar strokes. The classic syndromes are as follows: A silent lacunar infarction (SLI) is one type of silent stroke which usually shows no identifiable outward symptoms, and is thus termed "silent." Because stroke is a clinical diagnosis (that is, it is defined by clinical symptoms), there is debate about whether SLI are considered to be strokes, even though the pathophysiology is presumably the same. Individuals who have a SLI are often completely unaware they have had a stroke. This type of stroke often causes lesions in the surrounding brain tissue that are visibly detected via neuroimaging techniques such as MRI and computed axial tomography (CT scan). Silent strokes, including silent lacunar infarctions, have been shown to be much more common than previously thought, with an estimated prevalence rate of eleven million per year in the United States.