Silent stroke in the NINCDS Stroke Data Bank

Area of Science:

• Neurology
• Radiology
• Epidemiology

Background:

• Previous brain infarctions on computed tomography (CT) scans are frequently observed in patients without a documented stroke history.
• Approximately 11% of patients without a prior stroke diagnosis exhibit ischemic lesions on their initial CT scan, unrelated to the current stroke event.

Purpose of the Study:

• To investigate the occurrence, location, and CT characteristics of previously undetected ischemic brain lesions.
• To determine the association between these silent infarcts and their undetected status in patients.
• To analyze the impact of silent strokes on the clinical course and outcomes of a presenting stroke.

Main Methods:

• Review of Stroke Data Bank files.
• Analysis of CT scan findings in patients without a history of stroke.
• Categorization of lesions based on size (≤1 cm vs. >1 cm) and location (hemisphere, deep vs. superficial structures).

Main Results:

• Two distinct patterns of silent infarcts were identified: small, deep, left-hemisphere lesions (often asymptomatic) and larger, superficial, right-hemisphere lesions (associated with unrecognized symptoms).
• Risk factors for silent stroke were comparable to those for general stroke.
• The presence of a prior silent stroke did not significantly influence in-hospital complications or 30-day fatality rates from the presenting stroke.

Conclusions:

• Silent brain infarctions are a common finding in patients without a known stroke history.
• Lesion characteristics (size, location) correlate with clinical detectability.
• Silent strokes do not appear to worsen the prognosis of a subsequent stroke event.